13.5.19

[tests] Encode/decode doc with attribute changes

.babelrc

@@ -1,12 +0,0 @@
-{
-  "presets": [
-    ["latest", {
-      "es2015": {
-        "modules": false
-      }
-    }]
-  ],
-  "plugins": [
-    "external-helpers"
-  ]
-}

.circleci/config.yml

@@ -0,0 +1,7 @@
+version: 2.1
+orbs:
+  node: circleci/node@3.0.0
+workflows:
+  node-tests:
+    jobs:
+      - node/test

.flowconfig

@@ -1,12 +0,0 @@
-[ignore]
-.*/node_modules/.*
-.*/dist/.*
-.*/build/.*
-
-[include]
-./src/
-
-[libs]
-./declarations/
-
-[options]

.github/workflows/node.js.yml

@@ -0,0 +1,29 @@
+# This workflow will do a clean install of node dependencies, build the source code and run tests across different versions of node
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-nodejs-with-github-actions
+
+name: Node.js CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 14.x]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: npm ci
+    - run: npm run build --if-present
+    - run: npm test

.github/workflows/nodejs.yml

@@ -0,0 +1,31 @@
+# This workflow will do a clean install of node dependencies, build the source code and run tests across different versions of node
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-nodejs-with-github-actions
+
+name: Node.js CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 13.x]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: npm ci
+    - run: npm run lint
+    - run: npm run test-extensive
+      env:
+        CI: true

.gitignore

@@ -1,15 +1,4 @@
 node_modules
-bower_components
-build
-build_test
-.directory
-.codio
-.settings
-.jshintignore
-.jshintrc
-.validate.json
-/y.js
-/y.js.map
-/y-*
+dist
 .vscode
-jsconfig.json
+docs

.jsdoc.json

@@ -0,0 +1,52 @@
+{
+  "sourceType": "module",
+  "tags": {
+    "allowUnknownTags": true,
+    "dictionaries": ["jsdoc"]
+  },
+  "source": {
+    "include": ["./src"],
+    "includePattern": ".js$"
+  },
+  "plugins": [
+    "plugins/markdown"
+  ],
+  "templates": {
+    "referenceTitle": "Yjs",
+    "disableSort": false,
+    "useCollapsibles": true,
+    "collapse": true,
+    "resources": {
+      "yjs.dev": "Website",
+      "docs.yjs.dev": "Docs",
+      "discuss.yjs.dev": "Forum",
+      "https://gitter.im/Yjs/community": "Chat"
+    },
+    "logo": {
+      "url": "https://yjs.dev/images/logo/yjs-512x512.png",
+      "width": "162px",
+      "height": "162px",
+      "link": "/"
+    },
+    "tabNames": {
+      "api": "API",
+      "tutorials": "Examples"
+    },
+    "footerText": "Shared Editing",
+    "css": [
+      "./style.css"
+    ],
+    "default": {
+      "staticFiles": {
+          "include": []
+      }
+    }
+  },
+  "opts": {
+    "destination": "./docs/",
+    "encoding": "utf8",
+    "private": false,
+    "recurse": true,
+    "template": "./node_modules/tui-jsdoc-template"
+  }
+}

.markdownlint.json

@@ -0,0 +1,4 @@
+{
+  "default": true,
+  "no-inline-html": false
+}

INTERNALS.md

@@ -0,0 +1,179 @@
+# Yjs Internals
+
+This document roughly explains how Yjs works internally. There is a complete
+walkthrough of the Yjs codebase available as a recording:
+https://youtu.be/0l5XgnQ6rB4
+
+The Yjs CRDT algorithm is described in the [YATA
+paper](https://www.researchgate.net/publication/310212186_Near_Real-Time_Peer-to-Peer_Shared_Editing_on_Extensible_Data_Types)
+from 2016. For an algorithmic view of how it works, the paper is a reasonable
+place to start. There are a handful of small improvements implemented in Yjs
+which aren't described in the paper. The most notable is that items have an
+`originRight` as well as an `origin` property, which improves performance when
+many concurrent inserts happen after the same character.
+
+At its heart, Yjs is a list CRDT. Everything is squeezed into a list in order to
+reuse the CRDT resolution algorithm:
+
+- Arrays are easy - they're lists of arbitrary items.
+- Text is a list of characters, optionally punctuated by formatting markers and
+  embeds for rich text support. Several characters can be wrapped in a single
+linked list `Item` (this is also known as the compound representation of
+CRDTs). More information about this in [this blog
+article](https://blog.kevinjahns.de/are-crdts-suitable-for-shared-editing/).
+- Maps are lists of entries. The last inserted entry for each key is used, and
+  all other duplicates for each key are flagged as deleted.
+
+Each client is assigned a unique *clientID* property on first insert. This is a
+random 53-bit integer (53 bits because that fits in the javascript safe integer
+range).
+
+## List items
+
+Each item in a Yjs list is made up of two objects:
+
+- An `Item` (*src/structs/Item.js*). This is used to relate the item to other
+  adjacent items.
+- An object in the `AbstractType` hierarchy (subclasses of
+  *src/types/AbstractType.js* - eg `YText`). This stores the actual content in
+the Yjs document.
+
+The item and type object pair have a 1-1 mapping. The item's `content` field
+references the AbstractType object and the AbstractType object's `_item` field
+references the item.
+
+Everything inserted in a Yjs document is given a unique ID, formed from a
+*ID(clientID, clock)* pair (also known as a [Lamport
+Timestamp](https://en.wikipedia.org/wiki/Lamport_timestamp)). The clock counts
+up from 0 with the first inserted character or item a client makes. This is
+similar to automerge's operation IDs, but note that the clock is only
+incremented by inserts. Deletes are handled in a very different way (see
+below).
+
+If a run of characters is inserted into a document (eg `"abc"`), the clock will
+be incremented for each character (eg 3 times here). But Yjs will only add a
+single `Item` into the list. This has no effect on the core CRDT algorithm, but
+the optimization dramatically decreases the number of javascript objects
+created during normal text editing. This optimization only applies if the
+characters share the same clientID, they're inserted in order, and all
+characters have either been deleted or all characters are not deleted. The item
+will be split if the run is interrupted for any reason (eg a character in the
+middle of the run is deleted).
+
+When an item is created, it stores a reference to the IDs of the preceeding and
+succeeding item. These are stored in the item's `origin` and `originRight`
+fields, respectively. These are used when peers concurrently insert at the same
+location in a document. Though quite rare in practice, Yjs needs to make sure
+the list items always resolve to the same order on all peers. The actual logic
+is relatively simple - its only a couple dozen lines of code and it lives in
+the `Item#integrate()` method. The YATA paper has much more detail on the this
+algorithm.
+
+### Item Storage
+
+The items themselves are stored in two data structures and a cache:
+
+- The items are stored in a tree of doubly-linked lists in *document order*.
+  Each item has `left` and `right` properties linking to its siblings in the
+document. Items also have a `parent` property to reference their parent in the
+document tree (null at the root). (And you can access an item's children, if
+any, through `item.content`).
+- All items are referenced in *insertion order* inside the struct store
+  (*src/utils/StructStore.js*). This references the list of items inserted by
+for each client, in chronological order. This is used to find an item in the
+tree with a given ID (using a binary search). It is also used to efficiently
+gather the operations a peer is missing during sync (more on this below).
+
+When a local insert happens, Yjs needs to map the insert position in the
+document (eg position 1000) to an ID. With just the linked list, this would
+require a slow O(n) linear scan of the list. But when editing a document, most
+inserts are either at the same position as the last insert, or nearby. To
+improve performance, Yjs stores a cache of the 10 most recently looked up
+insert positions in the document. This is consulted and updated when a position
+is looked up to improve performance in the average case. The cache is updated
+using a heuristic that is still changing (currently, it is updated when a new
+position significantly diverges from existing markers in the cache). Internally
+this is referred to as the skip list / fast search marker.
+
+### Deletions
+
+Deletions in Yjs are treated very differently from insertions. Insertions are
+implemented as a sequential operation based CRDT, but deletions are treated as
+a simpler state based CRDT.
+
+When an item has been deleted by any peer, at any point in history, it is
+flagged as deleted on the item. (Internally Yjs uses the `info` bitfield.) Yjs
+does not record metadata about a deletion:
+
+- No data is kept on *when* an item was deleted, or which user deleted it.
+- The struct store does not contain deletion records
+- The clientID's clock is not incremented
+
+If garbage collection is enabled in Yjs, when an object is deleted its content
+is discarded. If a deleted object contains children (eg a field is deleted in
+an object), the content is replaced with a `GC` object (*src/structs/GC.js*).
+This is a very lightweight structure - it only stores the length of the removed
+content.
+
+Yjs has some special logic to share which content in a document has been
+deleted:
+
+- When a delete happens, as well as marking the item, the deleted IDs are
+  listed locally within the transaction. (See below for more information about
+transactions.) When a transaction has been committed locally, the set of
+deleted items is appended to a transaction's update message.
+- A snapshot (a marked point in time in the Yjs history) is specified using
+  both the set of (clientID, clock) pairs *and* the set of all deleted item
+IDs. The deleted set is O(n), but because deletions usually happen in runs,
+this data set is usually tiny in practice. (The real world editing trace from
+the B4 benchmark document contains 182k inserts and 77k deleted characters. The
+deleted set size in a snapshot is only 4.5Kb).
+
+## Transactions
+
+All updates in Yjs happen within a *transaction*. (Defined in
+*src/utils/Transaction.js*.)
+
+The transaction collects a set of updates to the Yjs document to be applied on
+remote peers atomically. Once a transaction has been committed locally, it
+generates a compressed *update message* which is broadcast to synchronized
+remote peers to notify them of the local change. The update message contains:
+
+- The set of newly inserted items
+- The set of items deleted within the transaction.
+
+## Network protocol
+
+The network protocol is not really a part of Yjs. There are a few relevant
+concepts that can be used to create a custom network protocol:
+
+* `update`: The Yjs document can be encoded to an *update* object that can be
+  parsed to reconstruct the document. Also every change on the document fires
+an incremental document updates that allows clients to sync with each other.
+The update object is an Uint8Array that efficiently encodes `Item` objects and
+the delete set.
+* `state vector`: A state vector defines the know state of each user (a set of
+  tubles `(client, clock)`). This object is also efficiently encoded as a
+Uint8Array.
+
+The client can ask a remote client for missing document updates by sending
+their state vector (often referred to as *sync step 1*). The remote peer can
+compute the missing `Item` objects using the `clocks` of the respective clients
+and compute a minimal update message that reflects all missing updates (sync
+step 2).
+
+An implementation of the syncing process is in
+[y-protocols](https://github.com/yjs/y-protocols).
+
+## Snapshots
+
+A snapshot can be used to restore an old document state. It is a `state vector`
+\+ `delete set`. I client can restore an old document state by iterating through
+the sequence CRDT and ignoring all Items that have an `id.clock >
+stateVector[id.client].clock`. Instead of using `item.deleted` the client will
+use the delete set to find out if an item was deleted or not.
+
+It is not recommended to restore an old document state using snapshots,
+although that would certainly be possible. Instead, the old state should be
+computed by iterating through the newest state and using the additional
+information from the state vector.

examples/ace/index.html

@@ -1,32 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-    <style type="text/css" media="screen">
-    #aceContainer {
-        position: absolute;
-        top: 0;
-        right: 0;
-        bottom: 0;
-        left: 0;
-    }
-    .inserted {
-      position:absolute;
-      z-index:20;
-      background-color: #FFC107;
-    }
-    .deleted {
-      position:absolute;
-      z-index:20;
-      background-color: #FFC107;
-    }
-    </style>
-  </head>
-  <body>
-
-    <div id="aceContainer"></div>
-    <script src="../bower_components/yjs/y.js"></script>
-    <script src="../bower_components/ace-builds/src/ace.js"></script>
-
-    <script src="./index.js"></script>
-  </body>
-</html>

examples/ace/index.js

@@ -1,24 +0,0 @@
-/* global Y, ace */
-
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'ace-example'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    ace: 'Text' // y.share.textarea is of type Y.Text
-  }
-}).then(function (y) {
-  window.yAce = y
-
-  // bind the textarea to a shared text element
-  var editor = ace.edit('aceContainer')
-  editor.setTheme('ace/theme/chrome')
-  editor.getSession().setMode('ace/mode/javascript')
-
-  y.share.ace.bindAce(editor)
-})

examples/bower.json

@@ -1,29 +0,0 @@
-{
-  "name": "yjs-examples",
-  "version": "0.0.0",
-  "homepage": "y-js.org",
-  "authors": [
-    "Kevin Jahns <kevin.jahns@rwth-aachen.de>"
-  ],
-  "description": "Examples for Yjs",
-  "license": "MIT",
-  "ignore": [],
-  "dependencies": {
-    "yjs": "latest",
-    "y-array": "latest",
-    "y-map": "latest",
-    "y-memory": "latest",
-    "y-richtext": "latest",
-    "y-webrtc": "latest",
-    "y-websockets-client": "latest",
-    "y-text": "latest",
-    "y-indexeddb": "latest",
-    "y-xml": "latest",
-    "quill": "^1.0.0-rc.2",
-    "ace": "~1.2.3",
-    "ace-builds": "~1.2.3",
-    "jquery": "~2.2.2",
-    "d3": "^3.5.16",
-    "codemirror": "^5.25.0"
-  }
-}

examples/chat/index.html

@@ -1,18 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <body>
-    <style>
-      #chat p span {
-        color: blue;
-      }
-    </style>
-    <div id="chat"></div>
-    <form id="chatform">
-      <input name="username" type="text" style="width:15%;">
-      <input name="message" type="text" style="width:60%;">
-      <input type="submit" value="Send">
-    </form>
-    <script src="../bower_components/yjs/y.js"></script>
-    <script src="./index.js"></script>
-  </body>
-</html>

examples/chat/index.js

@@ -1,73 +0,0 @@
-/* global Y, chat */
-
-// initialize a shared object. This function call returns a promise!
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'chat-example'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    chat: 'Array'
-  }
-}).then(function (y) {
-  window.yChat = y
-  // This functions inserts a message at the specified position in the DOM
-  function appendMessage (message, position) {
-    var p = document.createElement('p')
-    var uname = document.createElement('span')
-    uname.appendChild(document.createTextNode(message.username + ': '))
-    p.appendChild(uname)
-    p.appendChild(document.createTextNode(message.message))
-    document.querySelector('#chat').insertBefore(p, chat.children[position] || null)
-  }
-  // This function makes sure that only 7 messages exist in the chat history.
-  // The rest is deleted
-  function cleanupChat () {
-    if (y.share.chat.length > 7) {
-      y.share.chat.delete(0, y.chat.length - 7)
-    }
-  }
-  // Insert the initial content
-  y.share.chat.toArray().forEach(appendMessage)
-  cleanupChat()
-
-  // whenever content changes, make sure to reflect the changes in the DOM
-  y.share.chat.observe(function (event) {
-    if (event.type === 'insert') {
-      for (let i = 0; i < event.length; i++) {
-        appendMessage(event.values[i], event.index + i)
-      }
-    } else if (event.type === 'delete') {
-      for (let i = 0; i < event.length; i++) {
-        chat.children[event.index].remove()
-      }
-    }
-    // concurrent insertions may result in a history > 7, so cleanup here
-    cleanupChat()
-  })
-  document.querySelector('#chatform').onsubmit = function (event) {
-    // the form is submitted
-    var message = {
-      username: this.querySelector('[name=username]').value,
-      message: this.querySelector('[name=message]').value
-    }
-    if (message.username.length > 0 && message.message.length > 0) {
-      if (y.share.chat.length > 6) {
-        // If we are goint to insert the 8th element, make sure to delete first.
-        y.share.chat.delete(0)
-      }
-      // Here we insert a message in the shared chat type.
-      // This will call the observe function (see line 40)
-      // and reflect the change in the DOM
-      y.share.chat.push([message])
-      this.querySelector('[name=message]').value = ''
-    }
-    // Do not send this form!
-    event.preventDefault()
-    return false
-  }
-})

examples/codemirror/index.html

@@ -1,23 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-  </head>
-  <body>
-    <div id="codeMirrorContainer"></div>
-
-    <script src="../bower_components/yjs/y.js"></script>
-    <script src="../bower_components/codemirror/lib/codemirror.js"></script>
-    <script src="../bower_components/codemirror/mode/javascript/javascript.js"></script>
-    <link rel="stylesheet" href="../bower_components/codemirror/lib/codemirror.css">
-    <style>
-      .CodeMirror {
-        position: fixed;
-        top: 0;
-        left: 0;
-        height: 100%;
-        width: 100%;
-      }
-    </style>
-    <script src="./index.js"></script>
-  </body>
-</html>

examples/codemirror/index.js

@@ -1,24 +0,0 @@
-/* global Y, CodeMirror */
-
-// initialize a shared object. This function call returns a promise!
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'codemirror-example'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    codemirror: 'Text' // y.share.codemirror is of type Y.Text
-  }
-}).then(function (y) {
-  window.yCodeMirror = y
-
-  var editor = CodeMirror(document.querySelector('#codeMirrorContainer'), {
-    mode: 'javascript',
-    lineNumbers: true
-  })
-  y.share.codemirror.bindCodeMirror(editor)
-})

examples/drawing/index.html

@@ -1,19 +0,0 @@
-<!DOCTYPE html>
-<html>
-<body>
-  <style>
-    path {
-      fill: none;
-      stroke: blue;
-      stroke-width: 1px;
-      stroke-linejoin: round;
-      stroke-linecap: round;
-    }
-  </style>
-  <button type="button" id="clearDrawingCanvas">Clear Drawing</button>
-  <svg id="drawingCanvas" viewbox="0 0 100 100" width="100%"></svg>
-  <script src="../bower_components/yjs/y.js"></script>
-  <script src="../bower_components/d3/d3.js"></script>
-  <script src="./index.js"></script>
-</body>
-</html>

examples/drawing/index.js

@@ -1,84 +0,0 @@
-/* globals Y, d3 */
-'strict mode'
-
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'drawing-example'
-    // url: 'localhost:1234'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    drawing: 'Array'
-  }
-}).then(function (y) {
-  window.yDrawing = y
-  var drawing = y.share.drawing
-  var renderPath = d3.svg.line()
-    .x(function (d) { return d[0] })
-    .y(function (d) { return d[1] })
-    .interpolate('basis')
-
-  var svg = d3.select('#drawingCanvas')
-    .call(d3.behavior.drag()
-      .on('dragstart', dragstart)
-      .on('drag', drag)
-      .on('dragend', dragend))
-
-  // create line from a shared array object and update the line when the array changes
-  function drawLine (yarray) {
-    var line = svg.append('path').datum(yarray.toArray())
-    line.attr('d', renderPath)
-    yarray.observe(function (event) {
-      // we only implement insert events that are appended to the end of the array
-      event.values.forEach(function (value) {
-        line.datum().push(value)
-      })
-      line.attr('d', renderPath)
-    })
-  }
-  // call drawLine every time an array is appended
-  y.share.drawing.observe(function (event) {
-    if (event.type === 'insert') {
-      event.values.forEach(drawLine)
-    } else {
-      // just remove all elements (thats what we do anyway)
-      svg.selectAll('path').remove()
-    }
-  })
-  // draw all existing content
-  for (var i = 0; i < drawing.length; i++) {
-    drawLine(drawing.get(i))
-  }
-
-  // clear canvas on request
-  document.querySelector('#clearDrawingCanvas').onclick = function () {
-    drawing.delete(0, drawing.length)
-  }
-
-  var sharedLine = null
-  function dragstart () {
-    drawing.insert(drawing.length, [Y.Array])
-    sharedLine = drawing.get(drawing.length - 1)
-  }
-
-  // After one dragged event is recognized, we ignore them for 33ms.
-  var ignoreDrag = null
-  function drag () {
-    if (sharedLine != null && ignoreDrag == null) {
-      ignoreDrag = window.setTimeout(function () {
-        ignoreDrag = null
-      }, 33)
-      sharedLine.push([d3.mouse(this)])
-    }
-  }
-
-  function dragend () {
-    sharedLine = null
-    window.clearTimeout(ignoreDrag)
-    ignoreDrag = null
-  }
-})

examples/jigsaw/index.html

@@ -1,23 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <style type="text/css">
-    .draggable {
-      cursor: move;
-    }
-  </style>
-</head>
-<body>
-  <svg id="puzzle-example" width="100%" viewBox="0 0 800 800">
-    <g>
-      <path d="M 311.76636,154.23389 C 312.14136,171.85693 318.14087,184.97998 336.13843,184.23047 C 354.13647,183.48047 351.88647,180.48096 354.88599,178.98096 C 357.8855,177.48096 368.38452,170.35693 380.00806,169.98193 C 424.61841,168.54297 419.78296,223.6001 382.25757,223.6001 C 377.75806,223.6001 363.51001,219.10107 356.38599,211.97656 C 349.26196,204.85254 310.64185,207.10254 314.76636,236.34863 C 316.34888,247.5708 324.08374,267.90723 324.84595,286.23486 C 325.29321,296.99414 323.17603,307.00635 321.58911,315.6377 C 360.11353,305.4585 367.73462,304.30518 404.00513,312.83936 C 410.37915,314.33887 436.62573,310.21436 421.25269,290.3418 C 405.87964,270.46924 406.25464,248.34717 417.12817,240.84814 C 428.00171,233.34912 446.74976,228.84961 457.99829,234.09912 C 469.24683,239.34814 484.61987,255.84619 475.24585,271.59424 C 465.87231,287.34229 452.74878,290.7168 456.49829,303.84033 C 460.2478,316.96387 479.74536,320.33838 500.74292,321.83789 C 509.70142,322.47803 527.97192,323.28467 542.10864,320.12939 C 549.91821,318.38672 556.92212,315.89502 562.46753,313.56396 C 561.40796,277.80664 560.84888,245.71729 560.3606,241.97314 C 558.85278,230.41455 542.49536,217.28564 525.86499,223.2251 C 520.61548,225.1001 519.86548,231.84912 505.24243,232.59912 C 444.92798,235.69238 462.06958,143.26709 525.86499,180.48096 C 539.52759,188.45068 575.19409,190.7583 570.10913,156.85889 C 567.85962,141.86035 553.98608,102.86523 553.98608,102.86523 C 553.98608,102.86523 477.23755,111.82227 451.99878,91.991699 C 441.50024,83.74292 444.87476,69.494629 449.37427,61.245605 C 453.87378,52.996582 465.12231,46.622559 464.74731,36.123779 C 463.02563,-12.086426 392.96704,-10.902832 396.5061,36.873535 C 397.25562,46.997314 406.62964,52.621582 410.75415,60.495605 C 420.00757,78.161377 405.50024,96.073486 384.50757,99.490723 C 377.36206,100.65381 349.17505,102.65332 320.39429,102.23486 C 319.677,102.22461 318.95923,102.21143 318.24194,102.19775 C 315.08423,120.9751 311.55688,144.39697 311.76636,154.23389 z " style="fill:#f2c569;stroke:#000000" id="path2502"/>
-      <path d="M 500.74292,321.83789 C 479.74536,320.33838 460.2478,316.96387 456.49829,303.84033 C 452.74878,290.7168 465.87231,287.34229 475.24585,271.59424 C 484.61987,255.84619 469.24683,239.34814 457.99829,234.09912 C 446.74976,228.84961 428.00171,233.34912 417.12817,240.84814 C 406.25464,248.34717 405.87964,270.46924 421.25269,290.3418 C 436.62573,310.21436 410.37915,314.33887 404.00513,312.83936 C 367.73462,304.30518 360.11353,305.4585 321.58911,315.6377 C 320.56372,321.21484 319.75854,326.2207 320.01538,330.46191 C 320.76538,342.83545 329.3894,385.95508 327.8894,392.7041 C 326.3894,399.45312 313.64136,418.20117 297.89331,407.32715 C 282.14526,396.45361 276.52075,393.4541 265.27222,394.5791 C 254.02368,395.70361 239.77563,402.07812 239.77563,419.32568 C 239.77563,436.57373 250.27417,449.69727 268.64673,447.82227 C 287.36353,445.9126 317.92163,423.11035 325.63989,452.69678 C 330.1394,469.94434 330.51392,487.19238 330.1394,498.44092 C 329.95825,503.87646 326.09985,518.06592 322.16089,531.28125 C 353.2854,532.73682 386.47095,531.26611 394.2561,529.93701 C 430.30933,523.78174 429.31909,496.09766 412.62866,477.44385 C 406.25464,470.31934 401.75513,455.32129 405.87964,444.82275 C 414.07056,423.97314 458.8064,422.17773 473.37134,438.82324 C 483.86987,450.82178 475.99585,477.44385 468.49683,482.69287 C 453.52222,493.17529 457.22485,516.83008 473.37134,528.06201 C 504.79126,549.91943 572.35913,535.56152 572.35913,535.56152 C 572.35913,535.56152 567.85962,498.06592 567.48462,471.81934 C 567.10962,445.57275 589.60669,450.07227 593.3562,450.07227 C 597.10571,450.07227 604.22974,455.32129 609.47925,459.4458 C 614.72876,463.57031 618.85327,469.94434 630.85181,470.69434 C 677.43726,473.60596 674.58813,420.7373 631.97632,413.32666 C 623.35229,411.82666 614.72876,416.32617 603.10522,424.57519 C 591.48169,432.82422 577.23315,425.32519 570.10913,417.45117 C 566.07788,412.99561 563.8479,360.16406 562.46753,313.56396 C 556.92212,315.89502 549.91821,318.38672 542.10864,320.12939 C 527.97192,323.28467 509.70142,322.47803 500.74292,321.83789 z " style="fill:#f3f3d6;stroke:#000000" id="path2504"/>
-      <path d="M 240.52563,141.86035 C 257.60327,159.6499 243.94507,188.68799 214.65356,190.22949 C 185.09448,191.78516 164.66675,157.17822 190.28589,136.61621 C 200.49585,128.42139 198.05786,114.12158 179.78296,106.98975 C 154.4187,97.091553 90.54419,107.73975 90.54419,107.73975 C 90.54419,107.73975 100.88794,135.11328 101.41772,168.48242 C 101.79272,192.104 68.796875,189.47949 63.172607,186.85498 C 57.54834,184.23047 45.924805,173.73145 37.675781,173.73145 C -14.411865,173.73145 -10.013184,245.84375 39.925537,232.22412 C 48.174316,229.97461 56.42334,220.97559 68.796875,222.47559 C 81.17041,223.9751 87.544434,232.59912 87.544434,246.09766 C 87.544434,252.51709 87.0354,281.24268 86.340576,312.87012 C 119.15894,313.67676 160.60962,314.46582 170.03442,313.58887 C 186.15698,312.08936 195.90601,301.59033 188.40698,293.3418 C 180.90796,285.09277 156.16089,256.59619 179.03296,239.34814 C 201.90503,222.10059 235.65112,231.84912 239.77563,247.22217 C 243.90015,262.59521 240.52563,273.46924 234.90112,279.09326 C 229.27661,284.71777 210.52905,298.96582 221.40259,308.71484 C 232.27661,318.46338 263.77222,330.83691 302.39282,320.71338 C 309.58862,318.82715 315.92114,317.13525 321.58911,315.6377 C 323.17603,307.00635 325.29321,296.99414 324.84595,286.23486 C 324.08374,267.90723 316.34888,247.5708 314.76636,236.34863 C 310.64185,207.10254 349.26196,204.85254 356.38599,211.97656 C 363.51001,219.10107 377.75806,223.6001 382.25757,223.6001 C 419.78296,223.6001 424.61841,168.54297 380.00806,169.98193 C 368.38452,170.35693 357.8855,177.48096 354.88599,178.98096 C 351.88647,180.48096 354.13647,183.48047 336.13843,184.23047 C 318.14087,184.97998 312.14136,171.85693 311.76636,154.23389 C 311.55688,144.39697 315.08423,120.9751 318.24194,102.19775 C 290.37524,101.67725 262.46069,98.968262 254.39868,97.991211 C 233.38013,95.443359 217.17456,117.53662 240.52563,141.86035 z " style="fill:#bebcdb;stroke:#000000" id="path2506"/>
-      <path d="M 325.63989,452.69678 C 317.92163,423.11035 287.36353,445.9126 268.64673,447.82227 C 250.27417,449.69727 239.77563,436.57373 239.77563,419.32568 C 239.77563,402.07812 254.02368,395.70361 265.27222,394.5791 C 276.52075,393.4541 282.14526,396.45361 297.89331,407.32715 C 313.64136,418.20117 326.3894,399.45313 327.8894,392.7041 C 329.3894,385.95508 320.76538,342.83545 320.01538,330.46191 C 319.75855,326.2207 320.56372,321.21484 321.58911,315.6377 C 315.92114,317.13525 309.58862,318.82715 302.39282,320.71338 C 263.77222,330.83691 232.27661,318.46338 221.40259,308.71484 C 210.52905,298.96582 229.27661,284.71777 234.90112,279.09326 C 240.52563,273.46924 243.90015,262.59521 239.77563,247.22217 C 235.65112,231.84912 201.90503,222.10059 179.03296,239.34814 C 156.16089,256.59619 180.90796,285.09277 188.40698,293.3418 C 195.90601,301.59033 186.15698,312.08936 170.03442,313.58887 C 160.60962,314.46582 119.15894,313.67676 86.340576,312.87012 C 85.573975,347.74561 84.581299,386.15088 83.794922,402.07812 C 82.295166,432.44922 109.29175,422.32568 115.66577,420.82568 C 122.04028,419.32568 126.16479,409.57715 143.03735,408.45215 C 185.9231,405.59326 186.09985,466.69629 144.16235,467.69482 C 128.41431,468.06982 113.79126,451.19678 108.16675,447.44727 C 102.54272,443.69775 87.919433,442.94775 83.794922,457.9458 C 82.01709,464.41113 78.118652,481.65137 78.098144,496.18994 C 78.071045,515.38037 82.295166,531.81201 82.295166,531.81201 C 82.295166,531.81201 105.54224,526.5625 149.41187,526.5625 C 193.28149,526.5625 199.65552,547.93506 194.78101,558.80859 C 189.90649,569.68213 181.28296,568.93213 179.40796,583.18066 C 172.7063,634.11133 253.34106,631.08203 249.14917,584.68018 C 247.96948,571.62354 237.16528,571.66699 232.27661,557.68359 C 222.17944,528.80273 244.64966,523.56299 257.39819,524.68799 C 263.59351,525.23437 290.95679,529.73389 320.75757,531.21582 C 321.22437,531.23877 321.69312,531.25928 322.16089,531.28125 C 326.09985,518.06592 329.95825,503.87646 330.1394,498.44092 C 330.51392,487.19238 330.1394,469.94434 325.63989,452.69678 z " style="fill:#d3ea9d;stroke:#000000" id="path2508"/>
-		</g>
-  </svg>
-  <script src="../bower_components/yjs/y.js"></script>
-  <script src="../bower_components/d3/d3.js"></script>
-  <script src="./index.js"></script>
-</body>
-</html>

examples/jigsaw/index.js

@@ -1,74 +0,0 @@
-/* @flow */
-/* global Y, d3 */
-
-// initialize a shared object. This function call returns a promise!
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'Puzzle-example'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    piece1: 'Map',
-    piece2: 'Map',
-    piece3: 'Map',
-    piece4: 'Map'
-  }
-}).then(function (y) {
-  window.yJigsaw = y
-  var origin // mouse start position - translation of piece
-  var drag = d3.behavior.drag()
-    .on('dragstart', function (params) {
-      // get the translation of the element
-      var translation = d3
-        .select(this)
-        .attr('transform')
-        .slice(10, -1)
-        .split(',')
-        .map(Number)
-      // mouse coordinates
-      var mouse = d3.mouse(this.parentNode)
-      origin = {
-        x: mouse[0] - translation[0],
-        y: mouse[1] - translation[1]
-      }
-    })
-    .on('drag', function () {
-      var mouse = d3.mouse(this.parentNode)
-      var x = mouse[0] - origin.x // =^= mouse - mouse at dragstart + translation at dragstart
-      var y = mouse[1] - origin.y
-      d3.select(this).attr('transform', 'translate(' + x + ',' + y + ')')
-    })
-    .on('dragend', function (piece, i) {
-      // save the current translation of the puzzle piece
-      var mouse = d3.mouse(this.parentNode)
-      var x = mouse[0] - origin.x
-      var y = mouse[1] - origin.y
-      piece.set('translation', {x: x, y: y})
-    })
-
-  var data = [y.share.piece1, y.share.piece2, y.share.piece3, y.share.piece4]
-  var pieces = d3.select(document.querySelector('#puzzle-example')).selectAll('path').data(data)
-
-  pieces
-    .classed('draggable', true)
-    .attr('transform', function (piece) {
-      var translation = piece.get('translation') || {x: 0, y: 0}
-      return 'translate(' + translation.x + ',' + translation.y + ')'
-    }).call(drag)
-
-  data.forEach(function (piece) {
-    piece.observe(function () {
-      // whenever a property of a piece changes, update the translation of the pieces
-      pieces
-        .transition()
-        .attr('transform', function (piece) {
-          var translation = piece.get('translation') || {x: 0, y: 0}
-          return 'translate(' + translation.x + ',' + translation.y + ')'
-        })
-    })
-  })
-})

examples/monaco/index.html

@@ -1,24 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-  </head>
-  <body>
-    <div id="monacoContainer"></div>
-    <style>
-      #monacoContainer {
-        position: fixed;
-        top: 0;
-        left: 0;
-        height: 100%;
-        width: 100%;
-      }
-    </style>
-    <script src="../bower_components/yjs/y.js"></script>
-    <script src="../bower_components/y-array/y-array.js"></script>
-    <script src="../bower_components/y-text/y-text.js"></script>
-    <script src="../bower_components/y-websockets-client/y-websockets-client.js"></script>
-    <script src="../bower_components/y-memory/y-memory.js"></script>
-    <script src="../node_modules/monaco-editor/min/vs/loader.js"></script>
-    <script src="./index.js"></script>
-  </body>
-</html>

examples/monaco/index.js

@@ -1,30 +0,0 @@
-/* global Y, monaco */
-
-require.config({ paths: { 'vs': '../node_modules/monaco-editor/min/vs' } })
-
-require(['vs/editor/editor.main'], function () {
-  // Initialize a shared object. This function call returns a promise!
-  Y({
-    db: {
-      name: 'memory'
-    },
-    connector: {
-      name: 'websockets-client',
-      room: 'monaco-example'
-    },
-    sourceDir: '/bower_components',
-    share: {
-      monaco: 'Text' // y.share.monaco is of type Y.Text
-    }
-  }).then(function (y) {
-    window.yMonaco = y
-
-    // Create Monaco editor
-    var editor = monaco.editor.create(document.getElementById('monacoContainer'), {
-      language: 'javascript'
-    })
-
-    // Bind to y.share.monaco
-    y.share.monaco.bindMonaco(editor)
-  })
-})

examples/package.json

@@ -1,16 +0,0 @@
-{
-  "name": "examples",
-  "version": "0.0.0",
-  "description": "",
-  "author": "Kevin Jahns",
-  "license": "MIT",
-  "dependencies": {
-    "monaco-editor": "^0.8.3"
-  },
-  "devDependencies": {
-    "standard": "^10.0.2"
-  },
-  "standard": {
-    "ignore": ["bower_components"]
-  }
-}

examples/quill/index.html

@@ -1,31 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <!-- quill does not include dist files! We are using the hosted version instead -->
-  <!--link rel="stylesheet" href="../bower_components/quill/dist/quill.snow.css" /-->
-  <link href="https://cdn.quilljs.com/1.0.4/quill.snow.css" rel="stylesheet">
-  <link href="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.css" rel="stylesheet">
-  <link href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.2.0/styles/monokai-sublime.min.css" rel="stylesheet">
-  <style>
-    #quill-container {
-      border: 1px solid gray;
-      box-shadow: 0px 0px 10px gray;
-    }
-  </style>
-</head>
-<body>
-  <div id="quill-container">
-    <div id="quill">
-    </div>
-  </div>
-
-  <script src="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.js" type="text/javascript"></script>
-  <script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.2.0/highlight.min.js" type="text/javascript"></script>
-  <script src="https://cdn.quilljs.com/1.0.4/quill.js"></script>
-  <!-- quill does not include dist files! We are using the hosted version instead (see above)
-  <script src="../bower_components/quill/dist/quill.js"></script>
-  -->
-  <script src="../bower_components/yjs/y.js"></script>
-  <script src="./index.js"></script>
-</body>
-</html>

examples/quill/index.js

@@ -1,39 +0,0 @@
-/* global Y, Quill */
-
-// initialize a shared object. This function call returns a promise!
-
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'richtext-example-quill-1.0-test'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    richtext: 'Richtext' // y.share.richtext is of type Y.Richtext
-  }
-}).then(function (y) {
-  window.yQuill = y
-
-  // create quill element
-  window.quill = new Quill('#quill', {
-    modules: {
-      formula: true,
-      syntax: true,
-      toolbar: [
-        [{ size: ['small', false, 'large', 'huge'] }],
-        ['bold', 'italic', 'underline'],
-        [{ color: [] }, { background: [] }],    // Snow theme fills in values
-        [{ script: 'sub' }, { script: 'super' }],
-        ['link', 'image'],
-        ['link', 'code-block'],
-        [{ list: 'ordered' }]
-      ]
-    },
-    theme: 'snow'
-  })
-  // bind quill to richtext type
-  y.share.richtext.bind(window.quill)
-})

examples/serviceworker/index.html

@@ -1,31 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <!-- quill does not include dist files! We are using the hosted version instead -->
-  <!--link rel="stylesheet" href="../bower_components/quill/dist/quill.snow.css" /-->
-  <link href="https://cdn.quilljs.com/1.0.4/quill.snow.css" rel="stylesheet">
-  <link href="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.css" rel="stylesheet">
-  <link href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.2.0/styles/monokai-sublime.min.css" rel="stylesheet">
-  <style>
-    #quill-container {
-      border: 1px solid gray;
-      box-shadow: 0px 0px 10px gray;
-    }
-  </style>
-</head>
-<body>
-  <div id="quill-container">
-    <div id="quill">
-    </div>
-  </div>
-
-  <script src="//cdnjs.cloudflare.com/ajax/libs/KaTeX/0.5.1/katex.min.js" type="text/javascript"></script>
-  <script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.2.0/highlight.min.js" type="text/javascript"></script>
-  <script src="https://cdn.quilljs.com/1.0.4/quill.js"></script>
-  <!-- quill does not include dist files! We are using the hosted version instead (see above)
-  <script src="../bower_components/quill/dist/quill.js"></script>
-  -->
-  <script src="../bower_components/yjs/y.js"></script>
-  <script src="./index.js"></script>
-</body>
-</html>

examples/serviceworker/index.js

@@ -1,49 +0,0 @@
-/* global Y, Quill */
-
-// register yjs service worker
-if ('serviceWorker' in navigator) {
-  // Register service worker
-  // it is important to copy yjs-sw-template to the root directory!
-  navigator.serviceWorker.register('./yjs-sw-template.js').then(function (reg) {
-    console.log('Yjs service worker registration succeeded. Scope is ' + reg.scope)
-  }).catch(function (err) {
-    console.error('Yjs service worker registration failed with error ' + err)
-  })
-}
-
-// initialize a shared object. This function call returns a promise!
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'serviceworker',
-    room: 'ServiceWorkerExample2'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    richtext: 'Richtext' // y.share.richtext is of type Y.Richtext
-  }
-}).then(function (y) {
-  window.yServiceWorker = y
-
-  // create quill element
-  window.quill = new Quill('#quill', {
-    modules: {
-      formula: true,
-      syntax: true,
-      toolbar: [
-        [{ size: ['small', false, 'large', 'huge'] }],
-        ['bold', 'italic', 'underline'],
-        [{ color: [] }, { background: [] }],    // Snow theme fills in values
-        [{ script: 'sub' }, { script: 'super' }],
-        ['link', 'image'],
-        ['link', 'code-block'],
-        [{ list: 'ordered' }]
-      ]
-    },
-    theme: 'snow'
-  })
-  // bind quill to richtext type
-  y.share.richtext.bind(window.quill)
-})

examples/serviceworker/yjs-sw-template.js

@@ -1,22 +0,0 @@
-/* eslint-env worker */
-
-// copy and modify this file
-
-self.DBConfig = {
-  name: 'indexeddb'
-}
-self.ConnectorConfig = {
-  name: 'websockets-client',
-  // url: '..',
-  options: {
-    jsonp: false
-  }
-}
-
-importScripts(
-  '/bower_components/yjs/y.js',
-  '/bower_components/y-memory/y-memory.js',
-  '/bower_components/y-indexeddb/y-indexeddb.js',
-  '/bower_components/y-websockets-client/y-websockets-client.js',
-  '/bower_components/y-serviceworker/yjs-sw-include.js'
-)

examples/textarea/index.html

@@ -1,12 +0,0 @@
-<!DOCTYPE html>
-<html>
-<body>
-  <textarea style="width:80%;" rows=40 id="textfield" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"></textarea>
-  <script src="../../y.js"></script>
-  <script src="../../../y-array/y-array.js"></script>
-  <script src="../../../y-text/dist/y-text.js"></script>
-  <script src="../../../y-memory/y-memory.js"></script>
-  <script src="../../../y-websockets-client/dist/y-websockets-client.js"></script>
-  <script src="./index.js"></script>
-</body>
-</html>

examples/textarea/index.js

@@ -1,23 +0,0 @@
-/* global Y */
-
-// initialize a shared object. This function call returns a promise!
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'Textarea-example'
-    // url: '127.0.0.1:1234'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    textarea: 'Text' // y.share.textarea is of type Y.Text
-  }
-}).then(function (y) {
-  window.yTextarea = y
-
-  // bind the textarea to a shared text element
-  y.share.textarea.bind(document.getElementById('textfield'))
-  // thats it..
-})

examples/xml/index.html

@@ -1,39 +0,0 @@
-<!DOCTYPE html>
-<html>
-</head>
-  <script src="../bower_components/yjs/y.js"></script>
-  <script src="../bower_components/jquery/dist/jquery.min.js"></script>
-  <script src="./index.js"></script>
-</head>
-<body>
-  <h1> Shared DOM Example </h1>
-  <p> Use native DOM function or jQuery to manipulate the shared DOM (window.sharedDom). </p>
-  <div class="command">
-    <button type="button">Execute</button>
-    <input type="text" value='$(sharedDom).append("<h3>Appended headline</h3>")' size="40"/>
-  </div>
-  <div class="command">
-    <button type="button">Execute</button>
-    <input type="text" value='$(sharedDom).attr("align","right")' size="40"/>
-  </div>
-  <div class="command">
-    <button type="button">Execute</button>
-    <input type="text" value='$(sharedDom).attr("style","color:blue;")' size="40"/>
-  </div>
-
-  <script>
-    var commands = document.querySelectorAll(".command");
-    Array.prototype.forEach.call(document.querySelectorAll('.command'), function (command) {
-      var execute = function(){
-        eval(command.querySelector("input").value);
-      }
-      command.querySelector("button").onclick = execute
-      $(command.querySelector("input")).keyup(function (e) {
-        if (e.keyCode == 13) {
-          execute()
-        }
-      })
-    })
-  </script>
-</body>
-</html>

examples/xml/index.js

@@ -1,21 +0,0 @@
-/* global Y */
-
-// initialize a shared object. This function call returns a promise!
-Y({
-  db: {
-    name: 'memory'
-  },
-  connector: {
-    name: 'websockets-client',
-    room: 'Xml-example'
-  },
-  sourceDir: '/bower_components',
-  share: {
-    xml: 'Xml("p")' // y.share.xml is of type Y.Xml with tagname "p"
-  }
-}).then(function (y) {
-  window.yXml = y
-  // bind xml type to a dom, and put it in body
-  window.sharedDom = y.share.xml.getDom()
-  document.body.appendChild(window.sharedDom)
-})

package.json

@@ -1,65 +1,91 @@
 {
   "name": "yjs",
-  "version": "13.0.0-2",
-  "description": "A framework for real-time p2p shared editing on any data",
-  "main": "./src/y.js",
+  "version": "13.5.19",
+  "description": "Shared Editing Library",
+  "main": "./dist/yjs.cjs",
+  "module": "./dist/yjs.mjs",
+  "types": "./dist/src/index.d.ts",
+  "type": "module",
+  "sideEffects": false,
+  "funding": {
+    "type": "GitHub Sponsors ❤",
+    "url": "https://github.com/sponsors/dmonad"
+  },
   "scripts": {
-    "test": "npm run lint",
-    "lint": "standard",
-    "dist": "rollup -c rollup.dist.js",
-    "serve": "concurrently 'serve ..' 'rollup -wc rollup.dist.js -o examples/bower_components/yjs/y.js'",
-    "postversion": "npm run dist",
-    "postpublish": "tag-dist-files --overwrite-existing-tag"
+    "test": "npm run dist && node ./dist/tests.cjs --repetition-time 50",
+    "test-extensive": "npm run lint && npm run dist && node ./dist/tests.cjs --production --repetition-time 10000",
+    "dist": "rm -rf dist && rollup -c && tsc",
+    "watch": "rollup -wc",
+    "lint": "markdownlint README.md && standard && tsc",
+    "docs": "rm -rf docs; jsdoc --configure ./.jsdoc.json --verbose --readme ./README.md --package ./package.json || true",
+    "serve-docs": "npm run docs && http-server ./docs/",
+    "preversion": "npm run lint && PRODUCTION=1 npm run dist && npm run docs && node ./dist/tests.cjs --repetition-time 1000 && test -e dist/src/index.d.ts && test -e dist/yjs.cjs && test -e dist/yjs.cjs",
+    "debug": "concurrently 'http-server -o test.html' 'npm run watch'",
+    "trace-deopt": "clear && rollup -c  && node --trace-deopt dist/test.cjs",
+    "trace-opt": "clear && rollup -c  && node --trace-opt dist/test.cjs",
+    "postinstall": "node ./sponsor-y.js"
+  },
+  "exports": {
+    ".": {
+      "import": "./dist/yjs.mjs",
+      "require": "./dist/yjs.cjs"
+    },
+    "./src/index.js": "./src/index.js",
+    "./tests/testHelper.js": "./tests/testHelper.js",
+    "./testHelper": "./dist/testHelper.mjs",
+    "./package.json": "./package.json"
   },
   "files": [
-    "y.*"
+    "dist/yjs.*",
+    "dist/src",
+    "src",
+    "tests/testHelper.js",
+    "sponsor-y.js"
   ],
+  "dictionaries": {
+    "test": "tests"
+  },
   "standard": {
     "ignore": [
-      "/y.js",
-      "/y.js.map"
+      "/dist",
+      "/node_modules",
+      "/docs"
     ]
   },
   "repository": {
     "type": "git",
-    "url": "https://github.com/y-js/yjs.git"
+    "url": "https://github.com/yjs/yjs.git"
   },
   "keywords": [
     "Yjs",
-    "OT",
-    "Collaboration",
-    "Synchronization",
-    "ShareJS",
-    "Coweb",
-    "Concurrency"
+    "CRDT",
+    "offline",
+    "offline-first",
+    "shared-editing",
+    "concurrency",
+    "collaboration"
   ],
   "author": "Kevin Jahns",
-  "email": "kevin.jahns@rwth-aachen.de",
+  "email": "kevin.jahns@protonmail.com",
   "license": "MIT",
   "bugs": {
-    "url": "https://github.com/y-js/yjs/issues"
-  },
-  "homepage": "http://y-js.org",
-  "devDependencies": {
-    "babel-cli": "^6.24.1",
-    "babel-plugin-external-helpers": "^6.22.0",
-    "babel-plugin-transform-regenerator": "^6.24.1",
-    "babel-plugin-transform-runtime": "^6.23.0",
-    "babel-preset-latest": "^6.24.1",
-    "chance": "^1.0.9",
-    "concurrently": "^3.4.0",
-    "rollup-plugin-babel": "^2.7.1",
-    "rollup-plugin-commonjs": "^8.0.2",
-    "rollup-plugin-inject": "^2.0.0",
-    "rollup-plugin-multi-entry": "^2.0.1",
-    "rollup-plugin-node-resolve": "^3.0.0",
-    "rollup-plugin-uglify": "^1.0.2",
-    "rollup-regenerator-runtime": "^6.23.1",
-    "rollup-watch": "^3.2.2",
-    "standard": "^10.0.2",
-    "tag-dist-files": "^0.1.6"
+    "url": "https://github.com/yjs/yjs/issues"
   },
+  "homepage": "https://docs.yjs.dev",
   "dependencies": {
-    "debug": "^2.6.8"
+    "lib0": "^0.2.42"
+  },
+  "devDependencies": {
+    "@rollup/plugin-commonjs": "^17.0.0",
+    "@rollup/plugin-node-resolve": "^11.2.1",
+    "concurrently": "^3.6.1",
+    "http-server": "^0.12.3",
+    "jsdoc": "^3.6.7",
+    "markdownlint-cli": "^0.23.2",
+    "rollup": "^2.58.0",
+    "standard": "^16.0.4",
+    "tui-jsdoc-template": "^1.2.2",
+    "typescript": "^4.4.4",
+    "y-protocols": "^1.0.5"
   }
 }

rollup.config.js

@@ -0,0 +1,111 @@
+import nodeResolve from '@rollup/plugin-node-resolve'
+import commonjs from '@rollup/plugin-commonjs'
+
+const localImports = process.env.LOCALIMPORTS
+
+const customModules = new Set([
+  'y-websocket',
+  'y-codemirror',
+  'y-ace',
+  'y-textarea',
+  'y-quill',
+  'y-dom',
+  'y-prosemirror'
+])
+/**
+ * @type {Set<any>}
+ */
+const customLibModules = new Set([
+  'lib0',
+  'y-protocols'
+])
+const debugResolve = {
+  resolveId (importee) {
+    if (importee === 'yjs') {
+      return `${process.cwd()}/src/index.js`
+    }
+    if (localImports) {
+      if (customModules.has(importee.split('/')[0])) {
+        return `${process.cwd()}/../${importee}/src/${importee}.js`
+      }
+      if (customLibModules.has(importee.split('/')[0])) {
+        return `${process.cwd()}/../${importee}`
+      }
+    }
+    return null
+  }
+}
+
+export default [{
+  input: './src/index.js',
+  output: {
+    name: 'Y',
+    file: 'dist/yjs.cjs',
+    format: 'cjs',
+    sourcemap: true,
+    paths: path => {
+      if (/^lib0\//.test(path)) {
+        return `lib0/dist/${path.slice(5)}.cjs`
+      }
+      return path
+    }
+  },
+  external: id => /^lib0\//.test(id)
+}, {
+  input: './src/index.js',
+  output: {
+    name: 'Y',
+    file: 'dist/yjs.mjs',
+    format: 'esm',
+    sourcemap: true
+  },
+  external: id => /^lib0\//.test(id)
+}, {
+  input: './tests/testHelper.js',
+  output: {
+    name: 'Y',
+    file: 'dist/testHelper.mjs',
+    format: 'esm',
+    sourcemap: true
+  },
+  external: id => /^lib0\//.test(id) || id === 'yjs',
+  plugins: [{
+    resolveId (importee) {
+      if (importee === '../src/index.js') {
+        return 'yjs'
+      }
+      return null
+    }
+  }]
+}, {
+  input: './tests/index.js',
+  output: {
+    name: 'test',
+    file: 'dist/tests.js',
+    format: 'iife',
+    sourcemap: true
+  },
+  plugins: [
+    debugResolve,
+    nodeResolve({
+      mainFields: ['module', 'browser', 'main']
+    }),
+    commonjs()
+  ]
+}, {
+  input: './tests/index.js',
+  output: {
+    name: 'test',
+    file: 'dist/tests.cjs',
+    format: 'cjs',
+    sourcemap: true
+  },
+  plugins: [
+    debugResolve,
+    nodeResolve({
+      mainFields: ['module', 'main']
+    }),
+    commonjs()
+  ],
+  external: ['isomorphic.js']
+}]

rollup.dist.js

@@ -1,47 +0,0 @@
-import inject from 'rollup-plugin-inject'
-import babel from 'rollup-plugin-babel'
-import uglify from 'rollup-plugin-uglify'
-import nodeResolve from 'rollup-plugin-node-resolve'
-import commonjs from 'rollup-plugin-commonjs'
-var pkg = require('./package.json')
-
-export default {
-  entry: 'src/y.js',
-  moduleName: 'Y',
-  format: 'umd',
-  plugins: [
-    nodeResolve({
-      main: true,
-      module: true,
-      browser: true
-    }),
-    commonjs(),
-    babel({
-      runtimeHelpers: true
-    }),
-    inject({
-      regeneratorRuntime: 'regenerator-runtime'
-    }),
-    uglify({
-      output: {
-        comments: function (node, comment) {
-          var text = comment.value
-          var type = comment.type
-          if (type === 'comment2') {
-            // multiline comment
-            return /@license/i.test(text)
-          }
-        }
-      }
-    })
-  ],
-  dest: 'y.js',
-  sourceMap: true,
-  banner: `
-/**
- * ${pkg.name} - ${pkg.description}
- * @version v${pkg.version}
- * @license ${pkg.license}
- */
-`
-}

rollup.test.js

@@ -1,20 +0,0 @@
-import nodeResolve from 'rollup-plugin-node-resolve'
-import commonjs from 'rollup-plugin-commonjs'
-import multiEntry from 'rollup-plugin-multi-entry'
-
-export default {
-  entry: 'tests/*.js',
-  moduleName: 'y-array-tests',
-  format: 'umd',
-  plugins: [
-    nodeResolve({
-      main: true,
-      module: true,
-      browser: true
-    }),
-    commonjs(),
-    multiEntry()
-  ],
-  dest: 'y-array.test.js',
-  sourceMap: true
-}

sponsor-y.js

@@ -0,0 +1,12 @@
+
+try {
+  const log = require('lib0/dist/logging.cjs')
+
+  log.print()
+  log.print(log.BOLD, log.GREEN, log.BOLD, 'Thank you for using Yjs ', log.RED, '❤\n')
+  log.print(
+    log.GREY,
+    'The project has grown considerably in the past year. Too much for me to maintain\nin my spare time. Several companies built their products with Yjs.\nYet, this project receives very little funding. Yjs is far from done. I want to\ncreate more awesome extensions and work on the growing number of open issues.\n', log.BOLD, 'Dear user, the future of this project entirely depends on you.\n')
+  log.print(log.BLUE, log.BOLD, 'Please start funding the project now: https://github.com/sponsors/dmonad \n')
+  log.print(log.GREY, '(This message will be removed when I achieved my funding goal)\n\n')
+} catch (e) { }

src/Connector.js

@@ -1,493 +0,0 @@
-/* @flow */
-'use strict'
-
-function canRead (auth) { return auth === 'read' || auth === 'write' }
-function canWrite (auth) { return auth === 'write' }
-
-export default function extendConnector (Y/* :any */) {
-  class AbstractConnector {
-    /* ::
-    y: YConfig;
-    role: SyncRole;
-    connections: Object;
-    isSynced: boolean;
-    userEventListeners: Array<Function>;
-    whenSyncedListeners: Array<Function>;
-    currentSyncTarget: ?UserId;
-    syncingClients: Array<UserId>;
-    forwardToSyncingClients: boolean;
-    debug: boolean;
-    syncStep2: Promise;
-    userId: UserId;
-    send: Function;
-    broadcast: Function;
-    broadcastOpBuffer: Array<Operation>;
-    protocolVersion: number;
-    */
-    /*
-      opts contains the following information:
-       role : String Role of this client ("master" or "slave")
-       userId : String Uniquely defines the user.
-       debug: Boolean Whether to print debug messages (optional)
-    */
-    constructor (y, opts) {
-      this.y = y
-      if (opts == null) {
-        opts = {}
-      }
-      // Prefer to receive untransformed operations. This does only work if
-      // this client receives operations from only one other client.
-      // In particular, this does not work with y-webrtc.
-      // It will work with y-websockets-client
-      this.preferUntransformed = opts.preferUntransformed || false
-      if (opts.role == null || opts.role === 'master') {
-        this.role = 'master'
-      } else if (opts.role === 'slave') {
-        this.role = 'slave'
-      } else {
-        throw new Error("Role must be either 'master' or 'slave'!")
-      }
-      this.log = Y.debug('y:connector')
-      this.logMessage = Y.debug('y:connector-message')
-      this.y.db.forwardAppliedOperations = opts.forwardAppliedOperations || false
-      this.role = opts.role
-      this.connections = {}
-      this.isSynced = false
-      this.userEventListeners = []
-      this.whenSyncedListeners = []
-      this.currentSyncTarget = null
-      this.syncingClients = []
-      this.forwardToSyncingClients = opts.forwardToSyncingClients !== false
-      this.debug = opts.debug === true
-      this.broadcastOpBuffer = []
-      this.protocolVersion = 11
-      this.authInfo = opts.auth || null
-      this.checkAuth = opts.checkAuth || function () { return Promise.resolve('write') } // default is everyone has write access
-      if (opts.generateUserId !== false) {
-        this.setUserId(Y.utils.generateGuid())
-      }
-    }
-    resetAuth (auth) {
-      if (this.authInfo !== auth) {
-        this.authInfo = auth
-        this.broadcast({
-          type: 'auth',
-          auth: this.authInfo
-        })
-      }
-    }
-    reconnect () {
-      this.log('reconnecting..')
-      return this.y.db.startGarbageCollector()
-    }
-    disconnect () {
-      this.log('discronnecting..')
-      this.connections = {}
-      this.isSynced = false
-      this.currentSyncTarget = null
-      this.syncingClients = []
-      this.whenSyncedListeners = []
-      this.y.db.stopGarbageCollector()
-      return this.y.db.whenTransactionsFinished()
-    }
-    repair () {
-      this.log('Repairing the state of Yjs. This can happen if messages get lost, and Yjs detects that something is wrong. If this happens often, please report an issue here: https://github.com/y-js/yjs/issues')
-      for (var name in this.connections) {
-        this.connections[name].isSynced = false
-      }
-      this.isSynced = false
-      this.currentSyncTarget = null
-      this.findNextSyncTarget()
-    }
-    setUserId (userId) {
-      if (this.userId == null) {
-        this.log('Set userId to "%s"', userId)
-        this.userId = userId
-        return this.y.db.setUserId(userId)
-      } else {
-        return null
-      }
-    }
-    onUserEvent (f) {
-      this.userEventListeners.push(f)
-    }
-    removeUserEventListener (f) {
-      this.userEventListeners = this.userEventListeners.filter(g => f !== g)
-    }
-    userLeft (user) {
-      if (this.connections[user] != null) {
-        this.log('User left: %s', user)
-        delete this.connections[user]
-        if (user === this.currentSyncTarget) {
-          this.currentSyncTarget = null
-          this.findNextSyncTarget()
-        }
-        this.syncingClients = this.syncingClients.filter(function (cli) {
-          return cli !== user
-        })
-        for (var f of this.userEventListeners) {
-          f({
-            action: 'userLeft',
-            user: user
-          })
-        }
-      }
-    }
-    userJoined (user, role) {
-      if (role == null) {
-        throw new Error('You must specify the role of the joined user!')
-      }
-      if (this.connections[user] != null) {
-        throw new Error('This user already joined!')
-      }
-      this.log('User joined: %s', user)
-      this.connections[user] = {
-        isSynced: false,
-        role: role
-      }
-      let defer = {}
-      defer.promise = new Promise(function (resolve) { defer.resolve = resolve })
-      this.connections[user].syncStep2 = defer
-      for (var f of this.userEventListeners) {
-        f({
-          action: 'userJoined',
-          user: user,
-          role: role
-        })
-      }
-      if (this.currentSyncTarget == null) {
-        this.findNextSyncTarget()
-      }
-    }
-    // Execute a function _when_ we are connected.
-    // If not connected, wait until connected
-    whenSynced (f) {
-      if (this.isSynced) {
-        f()
-      } else {
-        this.whenSyncedListeners.push(f)
-      }
-    }
-    findNextSyncTarget () {
-      if (this.currentSyncTarget != null) {
-        return // "The current sync has not finished!"
-      }
-
-      var syncUser = null
-      for (var uid in this.connections) {
-        if (!this.connections[uid].isSynced) {
-          syncUser = uid
-          break
-        }
-      }
-      var conn = this
-      if (syncUser != null) {
-        this.currentSyncTarget = syncUser
-        this.y.db.requestTransaction(function * () {
-          var stateSet = yield * this.getStateSet()
-          // var deleteSet = yield * this.getDeleteSet()
-          var answer = {
-            type: 'sync step 1',
-            stateSet: stateSet,
-            // deleteSet: deleteSet,
-            protocolVersion: conn.protocolVersion,
-            auth: conn.authInfo
-          }
-          if (conn.preferUntransformed && Object.keys(stateSet).length === 0) {
-            answer.preferUntransformed = true
-          }
-          conn.send(syncUser, answer)
-        })
-      } else {
-        if (!conn.isSynced) {
-          this.y.db.requestTransaction(function * () {
-            if (!conn.isSynced) {
-              // it is crucial that isSynced is set at the time garbageCollectAfterSync is called
-              conn.isSynced = true
-              // It is safer to remove this!
-              // TODO: remove: yield * this.garbageCollectAfterSync()
-              // call whensynced listeners
-              for (var f of conn.whenSyncedListeners) {
-                f()
-              }
-              conn.whenSyncedListeners = []
-            }
-          })
-        }
-      }
-    }
-    send (uid, message) {
-      this.log('Send \'%s\' to %s', message.type, uid)
-      this.logMessage('Message: %j', message)
-    }
-    broadcast (message) {
-      this.log('Broadcast \'%s\'', message.type)
-      this.logMessage('Message: %j', message)
-    }
-    /*
-      Buffer operations, and broadcast them when ready.
-    */
-    broadcastOps (ops) {
-      ops = ops.map(function (op) {
-        return Y.Struct[op.struct].encode(op)
-      })
-      var self = this
-      function broadcastOperations () {
-        if (self.broadcastOpBuffer.length > 0) {
-          self.broadcast({
-            type: 'update',
-            ops: self.broadcastOpBuffer
-          })
-          self.broadcastOpBuffer = []
-        }
-      }
-      if (this.broadcastOpBuffer.length === 0) {
-        this.broadcastOpBuffer = ops
-        this.y.db.whenTransactionsFinished().then(broadcastOperations)
-      } else {
-        this.broadcastOpBuffer = this.broadcastOpBuffer.concat(ops)
-      }
-    }
-    /*
-      You received a raw message, and you know that it is intended for Yjs. Then call this function.
-    */
-    receiveMessage (sender/* :UserId */, message/* :Message */) {
-      if (sender === this.userId) {
-        return Promise.resolve()
-      }
-      this.log('Receive \'%s\' from %s', message.type, sender)
-      this.logMessage('Message: %j', message)
-      if (message.protocolVersion != null && message.protocolVersion !== this.protocolVersion) {
-        this.log(
-          `You tried to sync with a yjs instance that has a different protocol version
-          (You: ${this.protocolVersion}, Client: ${message.protocolVersion}).
-          The sync was stopped. You need to upgrade your dependencies (especially Yjs & the Connector)!
-          `)
-        this.send(sender, {
-          type: 'sync stop',
-          protocolVersion: this.protocolVersion
-        })
-        return Promise.reject(new Error('Incompatible protocol version'))
-      }
-      if (message.auth != null && this.connections[sender] != null) {
-        // authenticate using auth in message
-        var auth = this.checkAuth(message.auth, this.y)
-        this.connections[sender].auth = auth
-        auth.then(auth => {
-          for (var f of this.userEventListeners) {
-            f({
-              action: 'userAuthenticated',
-              user: sender,
-              auth: auth
-            })
-          }
-        })
-      } else if (this.connections[sender] != null && this.connections[sender].auth == null) {
-        // authenticate without otherwise
-        this.connections[sender].auth = this.checkAuth(null, this.y)
-      }
-      if (this.connections[sender] != null && this.connections[sender].auth != null) {
-        return this.connections[sender].auth.then((auth) => {
-          if (message.type === 'sync step 1' && canRead(auth)) {
-            let conn = this
-            let m = message
-            let wait // wait for sync step 2 to complete
-            if (this.role === 'slave') {
-              wait = Promise.all(Object.keys(this.connections)
-                .map(uid => this.connections[uid])
-                .filter(conn => conn.role === 'master')
-                .map(conn => conn.syncStep2.promise)
-              )
-            } else {
-              wait = Promise.resolve()
-            }
-            wait.then(() => {
-              this.y.db.requestTransaction(function * () {
-                var currentStateSet = yield * this.getStateSet()
-                // TODO: remove
-                // if (canWrite(auth)) {
-                //  yield * this.applyDeleteSet(m.deleteSet)
-                // }
-
-                var ds = yield * this.getDeleteSet()
-                var answer = {
-                  type: 'sync step 2',
-                  stateSet: currentStateSet,
-                  deleteSet: ds,
-                  protocolVersion: this.protocolVersion,
-                  auth: this.authInfo
-                }
-                if (message.preferUntransformed === true && Object.keys(m.stateSet).length === 0) {
-                  answer.osUntransformed = yield * this.getOperationsUntransformed()
-                } else {
-                  answer.os = yield * this.getOperations(m.stateSet)
-                }
-                conn.send(sender, answer)
-                if (this.forwardToSyncingClients) {
-                  conn.syncingClients.push(sender)
-                  setTimeout(function () {
-                    conn.syncingClients = conn.syncingClients.filter(function (cli) {
-                      return cli !== sender
-                    })
-                    conn.send(sender, {
-                      type: 'sync done'
-                    })
-                  }, 5000) // TODO: conn.syncingClientDuration)
-                } else {
-                  conn.send(sender, {
-                    type: 'sync done'
-                  })
-                }
-              })
-            })
-          } else if (message.type === 'sync step 2' && canWrite(auth)) {
-            var db = this.y.db
-            let defer = this.connections[sender].syncStep2
-            let m = message
-            // apply operations first
-            db.requestTransaction(function * () {
-              // yield * this.applyDeleteSet(m.deleteSet)
-              if (m.osUntransformed != null) {
-                yield * this.applyOperationsUntransformed(m.osUntransformed, m.stateSet)
-              } else {
-                this.store.apply(m.os)
-              }
-              // defer.resolve()
-            })
-            // then apply ds
-            db.whenTransactionsFinished().then(() => {
-              db.requestTransaction(function * () {
-                yield * this.applyDeleteSet(m.deleteSet)
-              })
-              defer.resolve()
-            })
-            return defer.promise
-          } else if (message.type === 'sync done') {
-            var self = this
-            this.connections[sender].syncStep2.promise.then(function () {
-              self._setSyncedWith(sender)
-            })
-          } else if (message.type === 'update' && canWrite(auth)) {
-            if (this.forwardToSyncingClients) {
-              for (var client of this.syncingClients) {
-                this.send(client, message)
-              }
-            }
-            if (this.y.db.forwardAppliedOperations) {
-              var delops = message.ops.filter(function (o) {
-                return o.struct === 'Delete'
-              })
-              if (delops.length > 0) {
-                this.broadcastOps(delops)
-              }
-            }
-            this.y.db.apply(message.ops)
-          }
-        })
-      } else {
-        return Promise.reject(new Error('Unable to deliver message'))
-      }
-    }
-    _setSyncedWith (user) {
-      var conn = this.connections[user]
-      if (conn != null) {
-        conn.isSynced = true
-      }
-      if (user === this.currentSyncTarget) {
-        this.currentSyncTarget = null
-        this.findNextSyncTarget()
-      }
-    }
-    /*
-      Currently, the HB encodes operations as JSON. For the moment I want to keep it
-      that way. Maybe we support encoding in the HB as XML in the future, but for now I don't want
-      too much overhead. Y is very likely to get changed a lot in the future
-
-      Because we don't want to encode JSON as string (with character escaping, wich makes it pretty much unreadable)
-      we encode the JSON as XML.
-
-      When the HB support encoding as XML, the format should look pretty much like this.
-
-      does not support primitive values as array elements
-      expects an ltx (less than xml) object
-    */
-    parseMessageFromXml (m/* :any */) {
-      function parseArray (node) {
-        for (var n of node.children) {
-          if (n.getAttribute('isArray') === 'true') {
-            return parseArray(n)
-          } else {
-            return parseObject(n)
-          }
-        }
-      }
-      function parseObject (node/* :any */) {
-        var json = {}
-        for (var attrName in node.attrs) {
-          var value = node.attrs[attrName]
-          var int = parseInt(value, 10)
-          if (isNaN(int) || ('' + int) !== value) {
-            json[attrName] = value
-          } else {
-            json[attrName] = int
-          }
-        }
-        for (var n/* :any */ in node.children) {
-          var name = n.name
-          if (n.getAttribute('isArray') === 'true') {
-            json[name] = parseArray(n)
-          } else {
-            json[name] = parseObject(n)
-          }
-        }
-        return json
-      }
-      parseObject(m)
-    }
-    /*
-      encode message in xml
-      we use string because Strophe only accepts an "xml-string"..
-      So {a:4,b:{c:5}} will look like
-      <y a="4">
-        <b c="5"></b>
-      </y>
-      m - ltx element
-      json - Object
-    */
-    encodeMessageToXml (msg, obj) {
-      // attributes is optional
-      function encodeObject (m, json) {
-        for (var name in json) {
-          var value = json[name]
-          if (name == null) {
-            // nop
-          } else if (value.constructor === Object) {
-            encodeObject(m.c(name), value)
-          } else if (value.constructor === Array) {
-            encodeArray(m.c(name), value)
-          } else {
-            m.setAttribute(name, value)
-          }
-        }
-      }
-      function encodeArray (m, array) {
-        m.setAttribute('isArray', 'true')
-        for (var e of array) {
-          if (e.constructor === Object) {
-            encodeObject(m.c('array-element'), e)
-          } else {
-            encodeArray(m.c('array-element'), e)
-          }
-        }
-      }
-      if (obj.constructor === Object) {
-        encodeObject(msg.c('y', { xmlns: 'http://y.ninja/connector-stanza' }), obj)
-      } else if (obj.constructor === Array) {
-        encodeArray(msg.c('y', { xmlns: 'http://y.ninja/connector-stanza' }), obj)
-      } else {
-        throw new Error("I can't encode this json!")
-      }
-    }
-  }
-  Y.AbstractConnector = AbstractConnector
-}

src/Connectors/Test.js

@@ -1,178 +0,0 @@
-/* global getRandom, async */
-'use strict'
-
-module.exports = function (Y) {
-  var globalRoom = {
-    users: {},
-    buffers: {},
-    removeUser: function (user) {
-      for (var i in this.users) {
-        this.users[i].userLeft(user)
-      }
-      delete this.users[user]
-      delete this.buffers[user]
-    },
-    addUser: function (connector) {
-      this.users[connector.userId] = connector
-      this.buffers[connector.userId] = {}
-      for (var uname in this.users) {
-        if (uname !== connector.userId) {
-          var u = this.users[uname]
-          u.userJoined(connector.userId, 'master')
-          connector.userJoined(u.userId, 'master')
-        }
-      }
-    },
-    whenTransactionsFinished: function () {
-      var self = this
-      return new Promise(function (resolve, reject) {
-        // The connector first has to send the messages to the db.
-        // Wait for the checkAuth-function to resolve
-        // The test lib only has a simple checkAuth function: `() => Promise.resolve()`
-        // Just add a function to the event-queue, in order to wait for the event.
-        // TODO: this may be buggy in test applications (but it isn't be for real-life apps)
-        setTimeout(function () {
-          var ps = []
-          for (var name in self.users) {
-            ps.push(self.users[name].y.db.whenTransactionsFinished())
-          }
-          Promise.all(ps).then(resolve, reject)
-        }, 10)
-      })
-    },
-    flushOne: function flushOne () {
-      var bufs = []
-      for (var receiver in globalRoom.buffers) {
-        let buff = globalRoom.buffers[receiver]
-        var push = false
-        for (let sender in buff) {
-          if (buff[sender].length > 0) {
-            push = true
-            break
-          }
-        }
-        if (push) {
-          bufs.push(receiver)
-        }
-      }
-      if (bufs.length > 0) {
-        var userId = getRandom(bufs)
-        let buff = globalRoom.buffers[userId]
-        let sender = getRandom(Object.keys(buff))
-        var m = buff[sender].shift()
-        if (buff[sender].length === 0) {
-          delete buff[sender]
-        }
-        var user = globalRoom.users[userId]
-        return user.receiveMessage(m[0], m[1]).then(function () {
-          return user.y.db.whenTransactionsFinished()
-        }, function () {})
-      } else {
-        return false
-      }
-    },
-    flushAll: function () {
-      return new Promise(function (resolve) {
-        // flushes may result in more created operations,
-        // flush until there is nothing more to flush
-        function nextFlush () {
-          var c = globalRoom.flushOne()
-          if (c) {
-            while (c) {
-              c = globalRoom.flushOne()
-            }
-            globalRoom.whenTransactionsFinished().then(nextFlush)
-          } else {
-            c = globalRoom.flushOne()
-            if (c) {
-              c.then(function () {
-                globalRoom.whenTransactionsFinished().then(nextFlush)
-              })
-            } else {
-              resolve()
-            }
-          }
-        }
-        globalRoom.whenTransactionsFinished().then(nextFlush)
-      })
-    }
-  }
-  Y.utils.globalRoom = globalRoom
-
-  var userIdCounter = 0
-
-  class Test extends Y.AbstractConnector {
-    constructor (y, options) {
-      if (options === undefined) {
-        throw new Error('Options must not be undefined!')
-      }
-      options.role = 'master'
-      options.forwardToSyncingClients = false
-      super(y, options)
-      this.setUserId((userIdCounter++) + '').then(() => {
-        globalRoom.addUser(this)
-      })
-      this.globalRoom = globalRoom
-      this.syncingClientDuration = 0
-    }
-    receiveMessage (sender, m) {
-      return super.receiveMessage(sender, JSON.parse(JSON.stringify(m)))
-    }
-    send (userId, message) {
-      var buffer = globalRoom.buffers[userId]
-      if (buffer != null) {
-        if (buffer[this.userId] == null) {
-          buffer[this.userId] = []
-        }
-        buffer[this.userId].push(JSON.parse(JSON.stringify([this.userId, message])))
-      }
-    }
-    broadcast (message) {
-      for (var key in globalRoom.buffers) {
-        var buff = globalRoom.buffers[key]
-        if (buff[this.userId] == null) {
-          buff[this.userId] = []
-        }
-        buff[this.userId].push(JSON.parse(JSON.stringify([this.userId, message])))
-      }
-    }
-    isDisconnected () {
-      return globalRoom.users[this.userId] == null
-    }
-    reconnect () {
-      if (this.isDisconnected()) {
-        globalRoom.addUser(this)
-        super.reconnect()
-      }
-      return Y.utils.globalRoom.flushAll()
-    }
-    disconnect () {
-      var waitForMe = Promise.resolve()
-      if (!this.isDisconnected()) {
-        globalRoom.removeUser(this.userId)
-        waitForMe = super.disconnect()
-      }
-      var self = this
-      return waitForMe.then(function () {
-        return self.y.db.whenTransactionsFinished()
-      })
-    }
-    flush () {
-      var self = this
-      return async(function * () {
-        var buff = globalRoom.buffers[self.userId]
-        while (Object.keys(buff).length > 0) {
-          var sender = getRandom(Object.keys(buff))
-          var m = buff[sender].shift()
-          if (buff[sender].length === 0) {
-            delete buff[sender]
-          }
-          yield this.receiveMessage(m[0], m[1])
-        }
-        yield self.whenTransactionsFinished()
-      })
-    }
-  }
-
-  Y.Test = Test
-}

src/Database.js

@@ -1,605 +0,0 @@
-/* @flow */
-'use strict'
-
-export default function extendDatabase (Y /* :any */) {
-  /*
-    Partial definition of an OperationStore.
-    TODO: name it Database, operation store only holds operations.
-
-    A database definition must alse define the following methods:
-    * logTable() (optional)
-      - show relevant information information in a table
-    * requestTransaction(makeGen)
-      - request a transaction
-    * destroy()
-      - destroy the database
-  */
-  class AbstractDatabase {
-    /* ::
-    y: YConfig;
-    forwardAppliedOperations: boolean;
-    listenersById: Object;
-    listenersByIdExecuteNow: Array<Object>;
-    listenersByIdRequestPending: boolean;
-    initializedTypes: Object;
-    whenUserIdSetListener: ?Function;
-    waitingTransactions: Array<Transaction>;
-    transactionInProgress: boolean;
-    executeOrder: Array<Object>;
-    gc1: Array<Struct>;
-    gc2: Array<Struct>;
-    gcTimeout: number;
-    gcInterval: any;
-    garbageCollect: Function;
-    executeOrder: Array<any>; // for debugging only
-    userId: UserId;
-    opClock: number;
-    transactionsFinished: ?{promise: Promise, resolve: any};
-    transact: (x: ?Generator) => any;
-    */
-    constructor (y, opts) {
-      this.y = y
-      opts.gc = opts.gc === true
-      this.dbOpts = opts
-      var os = this
-      this.userId = null
-      var resolve_
-      this.userIdPromise = new Promise(function (resolve) {
-        resolve_ = resolve
-      })
-      this.userIdPromise.resolve = resolve_
-      // whether to broadcast all applied operations (insert & delete hook)
-      this.forwardAppliedOperations = false
-      // E.g. this.listenersById[id] : Array<Listener>
-      this.listenersById = {}
-      // Execute the next time a transaction is requested
-      this.listenersByIdExecuteNow = []
-      // A transaction is requested
-      this.listenersByIdRequestPending = false
-      /* To make things more clear, the following naming conventions:
-         * ls : we put this.listenersById on ls
-         * l : Array<Listener>
-         * id : Id (can't use as property name)
-         * sid : String (converted from id via JSON.stringify
-                         so we can use it as a property name)
-
-        Always remember to first overwrite
-        a property before you iterate over it!
-      */
-      // TODO: Use ES7 Weak Maps. This way types that are no longer user,
-      // wont be kept in memory.
-      this.initializedTypes = {}
-      this.waitingTransactions = []
-      this.transactionInProgress = false
-      this.transactionIsFlushed = false
-      if (typeof YConcurrencyTestingMode !== 'undefined') {
-        this.executeOrder = []
-      }
-      this.gc1 = [] // first stage
-      this.gc2 = [] // second stage -> after that, remove the op
-
-      function garbageCollect () {
-        return os.whenTransactionsFinished().then(function () {
-          if (os.gcTimeout > 0 && (os.gc1.length > 0 || os.gc2.length > 0)) {
-            if (!os.y.connector.isSynced) {
-              console.warn('gc should be empty when not synced!')
-            }
-            return new Promise((resolve) => {
-              os.requestTransaction(function * () {
-                if (os.y.connector != null && os.y.connector.isSynced) {
-                  for (var i = 0; i < os.gc2.length; i++) {
-                    var oid = os.gc2[i]
-                    yield * this.garbageCollectOperation(oid)
-                  }
-                  os.gc2 = os.gc1
-                  os.gc1 = []
-                }
-                // TODO: Use setInterval here instead (when garbageCollect is called several times there will be several timeouts..)
-                if (os.gcTimeout > 0) {
-                  os.gcInterval = setTimeout(garbageCollect, os.gcTimeout)
-                }
-                resolve()
-              })
-            })
-          } else {
-            // TODO: see above
-            if (os.gcTimeout > 0) {
-              os.gcInterval = setTimeout(garbageCollect, os.gcTimeout)
-            }
-            return Promise.resolve()
-          }
-        })
-      }
-      this.garbageCollect = garbageCollect
-      this.startGarbageCollector()
-
-      this.repairCheckInterval = !opts.repairCheckInterval ? 6000 : opts.repairCheckInterval
-      this.opsReceivedTimestamp = new Date()
-      this.startRepairCheck()
-    }
-    startGarbageCollector () {
-      this.gc = this.dbOpts.gc
-      if (this.gc) {
-        this.gcTimeout = !this.dbOpts.gcTimeout ? 100000 : this.dbOpts.gcTimeout
-      } else {
-        this.gcTimeout = -1
-      }
-      if (this.gcTimeout > 0) {
-        this.garbageCollect()
-      }
-    }
-    startRepairCheck () {
-      var os = this
-      if (this.repairCheckInterval > 0) {
-        this.repairCheckIntervalHandler = setInterval(function repairOnMissingOperations () {
-          /*
-            Case 1. No ops have been received in a while (new Date() - os.opsReceivedTimestamp > os.repairCheckInterval)
-              - 1.1 os.listenersById is empty. Then the state was correct the whole time. -> Nothing to do (nor to update)
-              - 1.2 os.listenersById is not empty.
-                      * Then the state was incorrect for at least {os.repairCheckInterval} seconds.
-                      * -> Remove everything in os.listenersById and sync again (connector.repair())
-            Case 2. An op has been received in the last {os.repairCheckInterval } seconds.
-                    It is not yet necessary to check for faulty behavior. Everything can still resolve itself. Wait for more messages.
-                    If nothing was received for a while and os.listenersById is still not emty, we are in case 1.2
-                    -> Do nothing
-
-            Baseline here is: we really only have to catch case 1.2..
-          */
-          if (
-            new Date() - os.opsReceivedTimestamp > os.repairCheckInterval &&
-            Object.keys(os.listenersById).length > 0 // os.listenersById is not empty
-          ) {
-            // haven't received operations for over {os.repairCheckInterval} seconds, resend state vector
-            os.listenersById = {}
-            os.opsReceivedTimestamp = new Date() // update so you don't send repair several times in a row
-            os.y.connector.repair()
-          }
-        }, this.repairCheckInterval)
-      }
-    }
-    stopRepairCheck () {
-      clearInterval(this.repairCheckIntervalHandler)
-    }
-    queueGarbageCollector (id) {
-      if (this.y.connector.isSynced && this.gc) {
-        this.gc1.push(id)
-      }
-    }
-    emptyGarbageCollector () {
-      return new Promise(resolve => {
-        var check = () => {
-          if (this.gc1.length > 0 || this.gc2.length > 0) {
-            this.garbageCollect().then(check)
-          } else {
-            resolve()
-          }
-        }
-        setTimeout(check, 0)
-      })
-    }
-    addToDebug () {
-      if (typeof YConcurrencyTestingMode !== 'undefined') {
-        var command /* :string */ = Array.prototype.map.call(arguments, function (s) {
-          if (typeof s === 'string') {
-            return s
-          } else {
-            return JSON.stringify(s)
-          }
-        }).join('').replace(/"/g, "'").replace(/,/g, ', ').replace(/:/g, ': ')
-        this.executeOrder.push(command)
-      }
-    }
-    getDebugData () {
-      console.log(this.executeOrder.join('\n'))
-    }
-    stopGarbageCollector () {
-      var self = this
-      this.gc = false
-      this.gcTimeout = -1
-      return new Promise(function (resolve) {
-        self.requestTransaction(function * () {
-          var ungc /* :Array<Struct> */ = self.gc1.concat(self.gc2)
-          self.gc1 = []
-          self.gc2 = []
-          for (var i = 0; i < ungc.length; i++) {
-            var op = yield * this.getOperation(ungc[i])
-            if (op != null) {
-              delete op.gc
-              yield * this.setOperation(op)
-            }
-          }
-          resolve()
-        })
-      })
-    }
-    /*
-      Try to add to GC.
-
-      TODO: rename this function
-
-      Rulez:
-      * Only gc if this user is online & gc turned on
-      * The most left element in a list must not be gc'd.
-        => There is at least one element in the list
-
-      returns true iff op was added to GC
-    */
-    * addToGarbageCollector (op, left) {
-      if (
-        op.gc == null &&
-        op.deleted === true &&
-        this.store.gc &&
-        this.store.y.connector.isSynced
-      ) {
-        var gc = false
-        if (left != null && left.deleted === true) {
-          gc = true
-        } else if (op.content != null && op.content.length > 1) {
-          op = yield * this.getInsertionCleanStart([op.id[0], op.id[1] + 1])
-          gc = true
-        }
-        if (gc) {
-          op.gc = true
-          yield * this.setOperation(op)
-          this.store.queueGarbageCollector(op.id)
-          return true
-        }
-      }
-      return false
-    }
-    removeFromGarbageCollector (op) {
-      function filter (o) {
-        return !Y.utils.compareIds(o, op.id)
-      }
-      this.gc1 = this.gc1.filter(filter)
-      this.gc2 = this.gc2.filter(filter)
-      delete op.gc
-    }
-    destroyTypes () {
-      for (var key in this.initializedTypes) {
-        var type = this.initializedTypes[key]
-        if (type._destroy != null) {
-          type._destroy()
-        } else {
-          console.error('The type you included does not provide destroy functionality, it will remain in memory (updating your packages will help).')
-        }
-      }
-    }
-    * destroy () {
-      clearTimeout(this.gcInterval)
-      this.gcInterval = null
-      this.stopRepairCheck()
-    }
-    setUserId (userId) {
-      if (!this.userIdPromise.inProgress) {
-        this.userIdPromise.inProgress = true
-        var self = this
-        self.requestTransaction(function * () {
-          self.userId = userId
-          var state = yield * this.getState(userId)
-          self.opClock = state.clock
-          self.userIdPromise.resolve(userId)
-        })
-      }
-      return this.userIdPromise
-    }
-    whenUserIdSet (f) {
-      this.userIdPromise.then(f)
-    }
-    getNextOpId (numberOfIds) {
-      if (numberOfIds == null) {
-        throw new Error('getNextOpId expects the number of created ids to create!')
-      } else if (this.userId == null) {
-        throw new Error('OperationStore not yet initialized!')
-      } else {
-        var id = [this.userId, this.opClock]
-        this.opClock += numberOfIds
-        return id
-      }
-    }
-    /*
-      Apply a list of operations.
-
-      * we save a timestamp, because we received new operations that could resolve ops in this.listenersById (see this.startRepairCheck)
-      * get a transaction
-      * check whether all Struct.*.requiredOps are in the OS
-      * check if it is an expected op (otherwise wait for it)
-      * check if was deleted, apply a delete operation after op was applied
-    */
-    apply (ops) {
-      this.opsReceivedTimestamp = new Date()
-      for (var i = 0; i < ops.length; i++) {
-        var o = ops[i]
-        if (o.id == null || o.id[0] !== this.y.connector.userId) {
-          var required = Y.Struct[o.struct].requiredOps(o)
-          if (o.requires != null) {
-            required = required.concat(o.requires)
-          }
-          this.whenOperationsExist(required, o)
-        }
-      }
-    }
-    /*
-      op is executed as soon as every operation requested is available.
-      Note that Transaction can (and should) buffer requests.
-    */
-    whenOperationsExist (ids, op) {
-      if (ids.length > 0) {
-        let listener = {
-          op: op,
-          missing: ids.length
-        }
-
-        for (let i = 0; i < ids.length; i++) {
-          let id = ids[i]
-          let sid = JSON.stringify(id)
-          let l = this.listenersById[sid]
-          if (l == null) {
-            l = []
-            this.listenersById[sid] = l
-          }
-          l.push(listener)
-        }
-      } else {
-        this.listenersByIdExecuteNow.push({
-          op: op
-        })
-      }
-
-      if (this.listenersByIdRequestPending) {
-        return
-      }
-
-      this.listenersByIdRequestPending = true
-      var store = this
-
-      this.requestTransaction(function * () {
-        var exeNow = store.listenersByIdExecuteNow
-        store.listenersByIdExecuteNow = []
-
-        var ls = store.listenersById
-        store.listenersById = {}
-
-        store.listenersByIdRequestPending = false
-
-        for (let key = 0; key < exeNow.length; key++) {
-          let o = exeNow[key].op
-          yield * store.tryExecute.call(this, o)
-        }
-
-        for (var sid in ls) {
-          var l = ls[sid]
-          var id = JSON.parse(sid)
-          var op
-          if (typeof id[1] === 'string') {
-            op = yield * this.getOperation(id)
-          } else {
-            op = yield * this.getInsertion(id)
-          }
-          if (op == null) {
-            store.listenersById[sid] = l
-          } else {
-            for (let i = 0; i < l.length; i++) {
-              let listener = l[i]
-              let o = listener.op
-              if (--listener.missing === 0) {
-                yield * store.tryExecute.call(this, o)
-              }
-            }
-          }
-        }
-      })
-    }
-    /*
-      Actually execute an operation, when all expected operations are available.
-    */
-    /* :: // TODO: this belongs somehow to transaction
-    store: Object;
-    getOperation: any;
-    isGarbageCollected: any;
-    addOperation: any;
-    whenOperationsExist: any;
-    */
-    * tryExecute (op) {
-      this.store.addToDebug('yield * this.store.tryExecute.call(this, ', JSON.stringify(op), ')')
-      if (op.struct === 'Delete') {
-        yield * Y.Struct.Delete.execute.call(this, op)
-        // this is now called in Transaction.deleteOperation!
-        // yield * this.store.operationAdded(this, op)
-      } else {
-        // check if this op was defined
-        var defined = yield * this.getInsertion(op.id)
-        while (defined != null && defined.content != null) {
-          // check if this op has a longer content in the case it is defined
-          if (defined.id[1] + defined.content.length < op.id[1] + op.content.length) {
-            var overlapSize = defined.content.length - (op.id[1] - defined.id[1])
-            op.content.splice(0, overlapSize)
-            op.id = [op.id[0], op.id[1] + overlapSize]
-            op.left = Y.utils.getLastId(defined)
-            op.origin = op.left
-            defined = yield * this.getOperation(op.id) // getOperation suffices here
-          } else {
-            break
-          }
-        }
-        if (defined == null) {
-          var opid = op.id
-          var isGarbageCollected = yield * this.isGarbageCollected(opid)
-          if (!isGarbageCollected) {
-            // TODO: reduce number of get / put calls for op ..
-            yield * Y.Struct[op.struct].execute.call(this, op)
-            yield * this.addOperation(op)
-            yield * this.store.operationAdded(this, op)
-            // operationAdded can change op..
-            op = yield * this.getOperation(opid)
-            // if insertion, try to combine with left
-            yield * this.tryCombineWithLeft(op)
-          }
-        }
-      }
-    }
-    /*
-     * Called by a transaction when an operation is added.
-     * This function is especially important for y-indexeddb, where several instances may share a single database.
-     * Every time an operation is created by one instance, it is send to all other instances and operationAdded is called
-     *
-     * If it's not a Delete operation:
-     *   * Checks if another operation is executable (listenersById)
-     *   * Update state, if possible
-     *
-     * Always:
-     *   * Call type
-     */
-    * operationAdded (transaction, op) {
-      if (op.struct === 'Delete') {
-        var type = this.initializedTypes[JSON.stringify(op.targetParent)]
-        if (type != null) {
-          yield * type._changed(transaction, op)
-        }
-      } else {
-        // increase SS
-        yield * transaction.updateState(op.id[0])
-        var opLen = op.content != null ? op.content.length : 1
-        for (let i = 0; i < opLen; i++) {
-          // notify whenOperation listeners (by id)
-          var sid = JSON.stringify([op.id[0], op.id[1] + i])
-          var l = this.listenersById[sid]
-          delete this.listenersById[sid]
-          if (l != null) {
-            for (var key in l) {
-              var listener = l[key]
-              if (--listener.missing === 0) {
-                this.whenOperationsExist([], listener.op)
-              }
-            }
-          }
-        }
-        var t = this.initializedTypes[JSON.stringify(op.parent)]
-
-        // if parent is deleted, mark as gc'd and return
-        if (op.parent != null) {
-          var parentIsDeleted = yield * transaction.isDeleted(op.parent)
-          if (parentIsDeleted) {
-            yield * transaction.deleteList(op.id)
-            return
-          }
-        }
-
-        // notify parent, if it was instanciated as a custom type
-        if (t != null) {
-          let o = Y.utils.copyOperation(op)
-          yield * t._changed(transaction, o)
-        }
-        if (!op.deleted) {
-          // Delete if DS says this is actually deleted
-          var len = op.content != null ? op.content.length : 1
-          var startId = op.id // You must not use op.id in the following loop, because op will change when deleted
-            // TODO: !! console.log('TODO: change this before commiting')
-          for (let i = 0; i < len; i++) {
-            var id = [startId[0], startId[1] + i]
-            var opIsDeleted = yield * transaction.isDeleted(id)
-            if (opIsDeleted) {
-              var delop = {
-                struct: 'Delete',
-                target: id
-              }
-              yield * this.tryExecute.call(transaction, delop)
-            }
-          }
-        }
-      }
-    }
-    whenTransactionsFinished () {
-      if (this.transactionInProgress) {
-        if (this.transactionsFinished == null) {
-          var resolve_
-          var promise = new Promise(function (resolve) {
-            resolve_ = resolve
-          })
-          this.transactionsFinished = {
-            resolve: resolve_,
-            promise: promise
-          }
-        }
-        return this.transactionsFinished.promise
-      } else {
-        return Promise.resolve()
-      }
-    }
-    // Check if there is another transaction request.
-    // * the last transaction is always a flush :)
-    getNextRequest () {
-      if (this.waitingTransactions.length === 0) {
-        if (this.transactionIsFlushed) {
-          this.transactionInProgress = false
-          this.transactionIsFlushed = false
-          if (this.transactionsFinished != null) {
-            this.transactionsFinished.resolve()
-            this.transactionsFinished = null
-          }
-          return null
-        } else {
-          this.transactionIsFlushed = true
-          return function * () {
-            yield * this.flush()
-          }
-        }
-      } else {
-        this.transactionIsFlushed = false
-        return this.waitingTransactions.shift()
-      }
-    }
-    requestTransaction (makeGen/* :any */, callImmediately) {
-      this.waitingTransactions.push(makeGen)
-      if (!this.transactionInProgress) {
-        this.transactionInProgress = true
-        setTimeout(() => {
-          this.transact(this.getNextRequest())
-        }, 0)
-      }
-    }
-    /*
-      Get a created/initialized type.
-    */
-    getType (id) {
-      return this.initializedTypes[JSON.stringify(id)]
-    }
-    /*
-      Init type. This is called when a remote operation is retrieved, and transformed to a type
-      TODO: delete type from store.initializedTypes[id] when corresponding id was deleted!
-    */
-    * initType (id, args) {
-      var sid = JSON.stringify(id)
-      var t = this.store.initializedTypes[sid]
-      if (t == null) {
-        var op/* :MapStruct | ListStruct */ = yield * this.getOperation(id)
-        if (op != null) {
-          t = yield * Y[op.type].typeDefinition.initType.call(this, this.store, op, args)
-          this.store.initializedTypes[sid] = t
-        }
-      }
-      return t
-    }
-    /*
-     Create type. This is called when the local user creates a type (which is a synchronous action)
-    */
-    createType (typedefinition, id) {
-      var structname = typedefinition[0].struct
-      id = id || this.getNextOpId(1)
-      var op = Y.Struct[structname].create(id)
-      op.type = typedefinition[0].name
-
-      this.requestTransaction(function * () {
-        if (op.id[0] === '_') {
-          yield * this.setOperation(op)
-        } else {
-          yield * this.applyCreatedOperations([op])
-        }
-      })
-      var t = Y[op.type].typeDefinition.createType(this, op, typedefinition[1])
-      this.initializedTypes[JSON.stringify(op.id)] = t
-      return t
-    }
-  }
-  Y.AbstractDatabase = AbstractDatabase
-}

src/Database.spec.js

@@ -1,354 +0,0 @@
-/* global async, databases, describe, beforeEach, afterEach */
-/* eslint-env browser,jasmine,console */
-'use strict'
-
-var Y = require('./SpecHelper.js')
-
-for (let database of databases) {
-  describe(`Database (${database})`, function () {
-    var store
-    describe('DeleteStore', function () {
-      describe('Basic', function () {
-        beforeEach(function () {
-          store = new Y[database](null, {
-            gcTimeout: -1,
-            namespace: 'testing'
-          })
-        })
-        afterEach(function (done) {
-          store.requestTransaction(function * () {
-            yield * this.store.destroy()
-            done()
-          })
-        })
-        it('Deleted operation is deleted', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['u1', 10], 1)
-            expect(yield * this.isDeleted(['u1', 10])).toBeTruthy()
-            expect(yield * this.getDeleteSet()).toEqual({'u1': [[10, 1, false]]})
-            done()
-          })
-        }))
-        it('Deleted operation extends other deleted operation', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['u1', 10], 1)
-            yield * this.markDeleted(['u1', 11], 1)
-            expect(yield * this.isDeleted(['u1', 10])).toBeTruthy()
-            expect(yield * this.isDeleted(['u1', 11])).toBeTruthy()
-            expect(yield * this.getDeleteSet()).toEqual({'u1': [[10, 2, false]]})
-            done()
-          })
-        }))
-        it('Deleted operation extends other deleted operation', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['0', 3], 1)
-            yield * this.markDeleted(['0', 4], 1)
-            yield * this.markDeleted(['0', 2], 1)
-            expect(yield * this.getDeleteSet()).toEqual({'0': [[2, 3, false]]})
-            done()
-          })
-        }))
-        it('Debug #1', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['166', 0], 1)
-            yield * this.markDeleted(['166', 2], 1)
-            yield * this.markDeleted(['166', 0], 1)
-            yield * this.markDeleted(['166', 2], 1)
-            yield * this.markGarbageCollected(['166', 2], 1)
-            yield * this.markDeleted(['166', 1], 1)
-            yield * this.markDeleted(['166', 3], 1)
-            yield * this.markGarbageCollected(['166', 3], 1)
-            yield * this.markDeleted(['166', 0], 1)
-            expect(yield * this.getDeleteSet()).toEqual({'166': [[0, 2, false], [2, 2, true]]})
-            done()
-          })
-        }))
-        it('Debug #2', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['293', 0], 1)
-            yield * this.markDeleted(['291', 2], 1)
-            yield * this.markDeleted(['291', 2], 1)
-            yield * this.markGarbageCollected(['293', 0], 1)
-            yield * this.markDeleted(['293', 1], 1)
-            yield * this.markGarbageCollected(['291', 2], 1)
-            expect(yield * this.getDeleteSet()).toEqual({'291': [[2, 1, true]], '293': [[0, 1, true], [1, 1, false]]})
-            done()
-          })
-        }))
-        it('Debug #3', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['581', 0], 1)
-            yield * this.markDeleted(['581', 1], 1)
-            yield * this.markDeleted(['580', 0], 1)
-            yield * this.markDeleted(['580', 0], 1)
-            yield * this.markGarbageCollected(['581', 0], 1)
-            yield * this.markDeleted(['581', 2], 1)
-            yield * this.markDeleted(['580', 1], 1)
-            yield * this.markDeleted(['580', 2], 1)
-            yield * this.markDeleted(['580', 1], 1)
-            yield * this.markDeleted(['580', 2], 1)
-            yield * this.markGarbageCollected(['581', 2], 1)
-            yield * this.markGarbageCollected(['581', 1], 1)
-            yield * this.markGarbageCollected(['580', 1], 1)
-            expect(yield * this.getDeleteSet()).toEqual({'580': [[0, 1, false], [1, 1, true], [2, 1, false]], '581': [[0, 3, true]]})
-            done()
-          })
-        }))
-        it('Debug #4', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['544', 0], 1)
-            yield * this.markDeleted(['543', 2], 1)
-            yield * this.markDeleted(['544', 0], 1)
-            yield * this.markDeleted(['543', 2], 1)
-            yield * this.markGarbageCollected(['544', 0], 1)
-            yield * this.markDeleted(['545', 1], 1)
-            yield * this.markDeleted(['543', 4], 1)
-            yield * this.markDeleted(['543', 3], 1)
-            yield * this.markDeleted(['544', 1], 1)
-            yield * this.markDeleted(['544', 2], 1)
-            yield * this.markDeleted(['544', 1], 1)
-            yield * this.markDeleted(['544', 2], 1)
-            yield * this.markGarbageCollected(['543', 2], 1)
-            yield * this.markGarbageCollected(['543', 4], 1)
-            yield * this.markGarbageCollected(['544', 2], 1)
-            yield * this.markGarbageCollected(['543', 3], 1)
-            expect(yield * this.getDeleteSet()).toEqual({'543': [[2, 3, true]], '544': [[0, 1, true], [1, 1, false], [2, 1, true]], '545': [[1, 1, false]]})
-            done()
-          })
-        }))
-        it('Debug #5', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.applyDeleteSet({'16': [[1, 2, false]], '17': [[0, 1, true], [1, 3, false]]})
-            expect(yield * this.getDeleteSet()).toEqual({'16': [[1, 2, false]], '17': [[0, 1, true], [1, 3, false]]})
-            yield * this.applyDeleteSet({'16': [[1, 2, false]], '17': [[0, 4, true]]})
-            expect(yield * this.getDeleteSet()).toEqual({'16': [[1, 2, false]], '17': [[0, 4, true]]})
-            done()
-          })
-        }))
-        it('Debug #6', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.applyDeleteSet({'40': [[0, 3, false]]})
-            expect(yield * this.getDeleteSet()).toEqual({'40': [[0, 3, false]]})
-            yield * this.applyDeleteSet({'39': [[2, 2, false]], '40': [[0, 1, true], [1, 2, false]], '41': [[2, 1, false]]})
-            expect(yield * this.getDeleteSet()).toEqual({'39': [[2, 2, false]], '40': [[0, 1, true], [1, 2, false]], '41': [[2, 1, false]]})
-            done()
-          })
-        }))
-        it('Debug #7', async(function * (done) {
-          store.requestTransaction(function * () {
-            yield * this.markDeleted(['9', 2], 1)
-            yield * this.markDeleted(['11', 2], 1)
-            yield * this.markDeleted(['11', 4], 1)
-            yield * this.markDeleted(['11', 1], 1)
-            yield * this.markDeleted(['9', 4], 1)
-            yield * this.markDeleted(['10', 0], 1)
-            yield * this.markGarbageCollected(['11', 2], 1)
-            yield * this.markDeleted(['11', 2], 1)
-            yield * this.markGarbageCollected(['11', 3], 1)
-            yield * this.markDeleted(['11', 3], 1)
-            yield * this.markDeleted(['11', 3], 1)
-            yield * this.markDeleted(['9', 4], 1)
-            yield * this.markDeleted(['10', 0], 1)
-            yield * this.markGarbageCollected(['11', 1], 1)
-            yield * this.markDeleted(['11', 1], 1)
-            expect(yield * this.getDeleteSet()).toEqual({'9': [[2, 1, false], [4, 1, false]], '10': [[0, 1, false]], '11': [[1, 3, true], [4, 1, false]]})
-            done()
-          })
-        }))
-      })
-    })
-    describe('OperationStore', function () {
-      describe('Basic Tests', function () {
-        beforeEach(function () {
-          store = new Y[database](null, {
-            gcTimeout: -1,
-            namespace: 'testing'
-          })
-        })
-        afterEach(function (done) {
-          store.requestTransaction(function * () {
-            yield * this.store.destroy()
-            done()
-          })
-        })
-        it('debug #1', function (done) {
-          store.requestTransaction(function * () {
-            yield * this.os.put({id: [2]})
-            yield * this.os.put({id: [0]})
-            yield * this.os.delete([2])
-            yield * this.os.put({id: [1]})
-            expect(yield * this.os.find([0])).toBeTruthy()
-            expect(yield * this.os.find([1])).toBeTruthy()
-            expect(yield * this.os.find([2])).toBeFalsy()
-            done()
-          })
-        })
-        it('can add&retrieve 5 elements', function (done) {
-          store.requestTransaction(function * () {
-            yield * this.os.put({val: 'four', id: [4]})
-            yield * this.os.put({val: 'one', id: [1]})
-            yield * this.os.put({val: 'three', id: [3]})
-            yield * this.os.put({val: 'two', id: [2]})
-            yield * this.os.put({val: 'five', id: [5]})
-            expect((yield * this.os.find([1])).val).toEqual('one')
-            expect((yield * this.os.find([2])).val).toEqual('two')
-            expect((yield * this.os.find([3])).val).toEqual('three')
-            expect((yield * this.os.find([4])).val).toEqual('four')
-            expect((yield * this.os.find([5])).val).toEqual('five')
-            done()
-          })
-        })
-        it('5 elements do not exist anymore after deleting them', function (done) {
-          store.requestTransaction(function * () {
-            yield * this.os.put({val: 'four', id: [4]})
-            yield * this.os.put({val: 'one', id: [1]})
-            yield * this.os.put({val: 'three', id: [3]})
-            yield * this.os.put({val: 'two', id: [2]})
-            yield * this.os.put({val: 'five', id: [5]})
-            yield * this.os.delete([4])
-            expect(yield * this.os.find([4])).not.toBeTruthy()
-            yield * this.os.delete([3])
-            expect(yield * this.os.find([3])).not.toBeTruthy()
-            yield * this.os.delete([2])
-            expect(yield * this.os.find([2])).not.toBeTruthy()
-            yield * this.os.delete([1])
-            expect(yield * this.os.find([1])).not.toBeTruthy()
-            yield * this.os.delete([5])
-            expect(yield * this.os.find([5])).not.toBeTruthy()
-            done()
-          })
-        })
-      })
-      var numberOfOSTests = 1000
-      describe(`Random Tests - after adding&deleting (0.8/0.2) ${numberOfOSTests} times`, function () {
-        var elements = []
-        beforeAll(function (done) {
-          store = new Y[database](null, {
-            gcTimeout: -1,
-            namespace: 'testing'
-          })
-          store.requestTransaction(function * () {
-            for (var i = 0; i < numberOfOSTests; i++) {
-              var r = Math.random()
-              if (r < 0.8) {
-                var obj = [Math.floor(Math.random() * numberOfOSTests * 10000)]
-                if (!(yield * this.os.find(obj))) {
-                  elements.push(obj)
-                  yield * this.os.put({id: obj})
-                }
-              } else if (elements.length > 0) {
-                var elemid = Math.floor(Math.random() * elements.length)
-                var elem = elements[elemid]
-                elements = elements.filter(function (e) {
-                  return !Y.utils.compareIds(e, elem)
-                })
-                yield * this.os.delete(elem)
-              }
-            }
-            done()
-          })
-        })
-        afterAll(function (done) {
-          store.requestTransaction(function * () {
-            yield * this.store.destroy()
-            done()
-          })
-        })
-        it('can find every object', function (done) {
-          store.requestTransaction(function * () {
-            for (var id of elements) {
-              expect((yield * this.os.find(id)).id).toEqual(id)
-            }
-            done()
-          })
-        })
-
-        it('can find every object with lower bound search', function (done) {
-          store.requestTransaction(function * () {
-            for (var id of elements) {
-              var e = yield * this.os.findWithLowerBound(id)
-              expect(e.id).toEqual(id)
-            }
-            done()
-          })
-        })
-
-        it('iterating over a tree with lower bound yields the right amount of results', function (done) {
-          var lowerBound = elements[Math.floor(Math.random() * elements.length)]
-          var expectedResults = elements.filter(function (e, pos) {
-            return (Y.utils.smaller(lowerBound, e) || Y.utils.compareIds(e, lowerBound)) && elements.indexOf(e) === pos
-          }).length
-
-          var actualResults = 0
-          store.requestTransaction(function * () {
-            yield * this.os.iterate(this, lowerBound, null, function * (val) {
-              expect(val).toBeDefined()
-              actualResults++
-            })
-            expect(expectedResults).toEqual(actualResults)
-            done()
-          })
-        })
-
-        it('iterating over a tree without bounds yield the right amount of results', function (done) {
-          var lowerBound = null
-          var expectedResults = elements.filter(function (e, pos) {
-            return elements.indexOf(e) === pos
-          }).length
-          var actualResults = 0
-          store.requestTransaction(function * () {
-            yield * this.os.iterate(this, lowerBound, null, function * (val) {
-              expect(val).toBeDefined()
-              actualResults++
-            })
-            expect(expectedResults).toEqual(actualResults)
-            done()
-          })
-        })
-
-        it('iterating over a tree with upper bound yields the right amount of results', function (done) {
-          var upperBound = elements[Math.floor(Math.random() * elements.length)]
-          var expectedResults = elements.filter(function (e, pos) {
-            return (Y.utils.smaller(e, upperBound) || Y.utils.compareIds(e, upperBound)) && elements.indexOf(e) === pos
-          }).length
-
-          var actualResults = 0
-          store.requestTransaction(function * () {
-            yield * this.os.iterate(this, null, upperBound, function * (val) {
-              expect(val).toBeDefined()
-              actualResults++
-            })
-            expect(expectedResults).toEqual(actualResults)
-            done()
-          })
-        })
-
-        it('iterating over a tree with upper and lower bounds yield the right amount of results', function (done) {
-          var b1 = elements[Math.floor(Math.random() * elements.length)]
-          var b2 = elements[Math.floor(Math.random() * elements.length)]
-          var upperBound, lowerBound
-          if (Y.utils.smaller(b1, b2)) {
-            lowerBound = b1
-            upperBound = b2
-          } else {
-            lowerBound = b2
-            upperBound = b1
-          }
-          var expectedResults = elements.filter(function (e, pos) {
-            return (Y.utils.smaller(lowerBound, e) || Y.utils.compareIds(e, lowerBound)) &&
-              (Y.utils.smaller(e, upperBound) || Y.utils.compareIds(e, upperBound)) && elements.indexOf(e) === pos
-          }).length
-          var actualResults = 0
-          store.requestTransaction(function * () {
-            yield * this.os.iterate(this, lowerBound, upperBound, function * (val) {
-              expect(val).toBeDefined()
-              actualResults++
-            })
-            expect(expectedResults).toEqual(actualResults)
-            done()
-          })
-        })
-      })
-    })
-  })
-}

src/Notes.md

@@ -1,12 +0,0 @@
-
-# Notes
-
-### Terminology
-
-* DB: DataBase that holds all the information of the shared object. It is devided into the OS, DS, and SS. This can be a persistent database or an in-memory database. Depending on the type of database, it could make sense to store OS, DS, and SS in different tables, or maybe different databases.
-* OS: OperationStore holds all the operations. An operation is a js object with a fixed number of name fields.
-* DS: DeleteStore holds the information about which operations are deleted and which operations were garbage collected (no longer available in the OS).
-* SS: StateSet holds the current state of the OS. SS.getState(username) refers to the amount of operations that were received by that respective user.
-* Op: Operation defines an action on a shared type. But it is also the format in which we store the model of a type. This is why it is also called a Struct/Structure.
-* Type and Structure: We crearly distinguish between type and structure. Short explanation: A type (e.g. Strings, Numbers) have a number of functions that you can apply on them. (+) is well defined on both of them. They are *modeled* by a structure - the functions really change the structure of a type. Types can be implemented differently but still provide the same functionality. In Yjs, almost all types are realized as a doubly linked list (on which Yjs can provide eventual convergence)
-*

src/SpecHelper.js

@@ -1,404 +0,0 @@
-/* eslint-env browser, jasmine */
-
-/*
-  This is just a compilation of functions that help to test this library!
-*/
-
-// When testing, you store everything on the global object. We call it g
-
-var Y = require('./y.js')
-require('../../y-memory/src/Memory.js')(Y)
-require('../../y-array/src/Array.js')(Y)
-require('../../y-map/src/Map.js')(Y)
-require('../../y-indexeddb/src/IndexedDB.js')(Y)
-
-module.exports = Y
-
-var g
-if (typeof global !== 'undefined') {
-  g = global
-} else if (typeof window !== 'undefined') {
-  g = window
-} else {
-  throw new Error('No global object?')
-}
-g.g = g
-
-// Helper methods for the random number generator
-Math.seedrandom = require('seedrandom')
-
-g.generateRandomSeed = function generateRandomSeed () {
-  var seed
-  if (typeof window !== 'undefined' && window.location.hash.length > 1) {
-    seed = window.location.hash.slice(1) // first character is the hash!
-    console.warn('Using random seed that was specified in the url!')
-  } else {
-    seed = JSON.stringify(Math.random())
-  }
-  console.info('Using random seed: ' + seed)
-  g.setRandomSeed(seed)
-}
-
-g.setRandomSeed = function setRandomSeed (seed) {
-  Math.seedrandom.currentSeed = seed
-  Math.seedrandom(Math.seedrandom.currentSeed, { global: true })
-}
-
-g.generateRandomSeed()
-
-g.YConcurrencyTestingMode = true
-
-jasmine.DEFAULT_TIMEOUT_INTERVAL = 200000
-
-g.describeManyTimes = function describeManyTimes (times, name, f) {
-  for (var i = 0; i < times; i++) {
-    describe(name, f)
-  }
-}
-
-/*
-  Wait for a specified amount of time (in ms). defaults to 5ms
-*/
-function wait (t) {
-  if (t == null) {
-    t = 0
-  }
-  return new Promise(function (resolve) {
-    setTimeout(function () {
-      resolve()
-    }, t)
-  })
-}
-g.wait = wait
-
-g.databases = ['memory']
-if (typeof window !== 'undefined') {
-  g.databases.push('indexeddb')
-} else {
-  g.databases.push('leveldb')
-}
-/*
-  returns a random element of o.
-  works on Object, and Array
-*/
-function getRandom (o) {
-  if (o instanceof Array) {
-    return o[Math.floor(Math.random() * o.length)]
-  } else if (o.constructor === Object) {
-    return o[getRandom(Object.keys(o))]
-  }
-}
-g.getRandom = getRandom
-
-function getRandomNumber (n) {
-  if (n == null) {
-    n = 9999
-  }
-  return Math.floor(Math.random() * n)
-}
-g.getRandomNumber = getRandomNumber
-
-function getRandomString () {
-  var chars = 'abcdefghijklmnopqrstuvwxyzäüöABCDEFGHIJKLMNOPQRSTUVWXYZÄÜÖ'
-  var char = chars[getRandomNumber(chars.length)] // ü\n\n\n\n\n\n\n'
-  var length = getRandomNumber(7)
-  var string = ''
-  for (var i = 0; i < length; i++) {
-    string += char
-  }
-  return string
-}
-g.getRandomString = getRandomString
-
-function * applyTransactions (relAmount, numberOfTransactions, objects, users, transactions, noReconnect) {
-  g.generateRandomSeed() // create a new seed, so we can re-create the behavior
-  for (var i = 0; i < numberOfTransactions * relAmount + 1; i++) {
-    var r = Math.random()
-    if (r > 0.95) {
-      // 10% chance of toggling concurrent user interactions.
-      // There will be an artificial delay until ops can be executed by the type,
-      // therefore, operations of the database will be (pre)transformed until user operations arrive
-      yield (function simulateConcurrentUserInteractions (type) {
-        if (!(type instanceof Y.utils.CustomType) && type.y instanceof Y.utils.CustomType) {
-          // usually we expect type to be a custom type. But in YXml we share an object {y: YXml, dom: Dom} instead
-          type = type.y
-        }
-        if (type.eventHandler.awaiting === 0 && type.eventHandler._debuggingAwaiting !== true) {
-          type.eventHandler.awaiting = 1
-          type.eventHandler._debuggingAwaiting = true
-        } else {
-          // fixAwaitingInType will handle _debuggingAwaiting
-          return fixAwaitingInType(type)
-        }
-      })(getRandom(objects))
-    } else if (r >= 0.5) {
-      // 40% chance to flush
-      yield Y.utils.globalRoom.flushOne() // flushes for some user.. (not necessarily 0)
-    } else if (noReconnect || r >= 0.05) {
-      // 45% chance to create operation
-      var done = getRandom(transactions)(getRandom(objects))
-      if (done != null) {
-        yield done
-      } else {
-        yield wait()
-      }
-      yield Y.utils.globalRoom.whenTransactionsFinished()
-    } else {
-      // 5% chance to disconnect/reconnect
-      var u = getRandom(users)
-      yield Promise.all(objects.map(fixAwaitingInType))
-      if (u.connector.isDisconnected()) {
-        yield u.reconnect()
-      } else {
-        yield u.disconnect()
-      }
-      yield Promise.all(objects.map(fixAwaitingInType))
-    }
-  }
-}
-
-function fixAwaitingInType (type) {
-  if (!(type instanceof Y.utils.CustomType) && type.y instanceof Y.utils.CustomType) {
-    // usually we expect type to be a custom type. But in YXml we share an object {y: YXml, dom: Dom} instead
-    type = type.y
-  }
-  return new Promise(function (resolve) {
-    type.os.whenTransactionsFinished().then(function () {
-      // _debuggingAwaiting artificially increases the awaiting property. We need to make sure that we only do that once / reverse the effect once
-      type.os.requestTransaction(function * () {
-        if (type.eventHandler.awaiting > 0 && type.eventHandler._debuggingAwaiting === true) {
-          type.eventHandler._debuggingAwaiting = false
-          yield * type.eventHandler.awaitOps(this, function * () { /* mock function */ })
-        }
-        wait(50).then(type.os.whenTransactionsFinished()).then(wait(50)).then(resolve)
-      })
-    })
-  })
-}
-g.fixAwaitingInType = fixAwaitingInType
-
-g.applyRandomTransactionsNoGCNoDisconnect = async(function * applyRandomTransactions (users, objects, transactions, numberOfTransactions) {
-  yield * applyTransactions(1, numberOfTransactions, objects, users, transactions, true)
-  yield Y.utils.globalRoom.flushAll()
-  yield Promise.all(objects.map(fixAwaitingInType))
-})
-
-g.applyRandomTransactionsAllRejoinNoGC = async(function * applyRandomTransactions (users, objects, transactions, numberOfTransactions) {
-  yield * applyTransactions(1, numberOfTransactions, objects, users, transactions)
-  yield Promise.all(objects.map(fixAwaitingInType))
-  yield Y.utils.globalRoom.flushAll()
-  yield Promise.all(objects.map(fixAwaitingInType))
-  for (var u in users) {
-    yield Promise.all(objects.map(fixAwaitingInType))
-    yield users[u].reconnect()
-    yield Promise.all(objects.map(fixAwaitingInType))
-  }
-  yield Promise.all(objects.map(fixAwaitingInType))
-  yield Y.utils.globalRoom.flushAll()
-  yield Promise.all(objects.map(fixAwaitingInType))
-  yield g.garbageCollectAllUsers(users)
-})
-
-g.applyRandomTransactionsWithGC = async(function * applyRandomTransactions (users, objects, transactions, numberOfTransactions) {
-  yield * applyTransactions(1, numberOfTransactions, objects, users.slice(1), transactions)
-  yield Y.utils.globalRoom.flushAll()
-  yield Promise.all(objects.map(fixAwaitingInType))
-  for (var u in users) {
-    // TODO: here, we enforce that two users never sync at the same time with u[0]
-    //       enforce that in the connector itself!
-    yield users[u].reconnect()
-  }
-  yield Y.utils.globalRoom.flushAll()
-  yield Promise.all(objects.map(fixAwaitingInType))
-  yield g.garbageCollectAllUsers(users)
-})
-
-g.garbageCollectAllUsers = async(function * garbageCollectAllUsers (users) {
-  yield Y.utils.globalRoom.flushAll()
-  for (var i in users) {
-    yield users[i].db.emptyGarbageCollector()
-  }
-})
-
-g.compareAllUsers = async(function * compareAllUsers (users) {
-  var s1, s2 // state sets
-  var ds1, ds2 // delete sets
-  var allDels1, allDels2 // all deletions
-  var db1 = [] // operation store of user1
-
-  yield Y.utils.globalRoom.flushAll()
-  yield g.garbageCollectAllUsers(users)
-  yield Y.utils.globalRoom.flushAll()
-
-  // disconnect, then reconnect all users
-  // We do this to make sure that the gc is updated by everyone
-  for (var i = 0; i < users.length; i++) {
-    yield users[i].disconnect()
-    yield wait()
-    yield users[i].reconnect()
-  }
-  yield wait()
-  yield Y.utils.globalRoom.flushAll()
-
-  // t1 and t2 basically do the same. They define t[1,2], ds[1,2], and allDels[1,2]
-  function * t1 () {
-    s1 = yield * this.getStateSet()
-    ds1 = yield * this.getDeleteSet()
-    allDels1 = []
-    yield * this.ds.iterate(this, null, null, function * (d) {
-      allDels1.push(d)
-    })
-  }
-  function * t2 () {
-    s2 = yield * this.getStateSet()
-    ds2 = yield * this.getDeleteSet()
-    allDels2 = []
-    yield * this.ds.iterate(this, null, null, function * (d) {
-      allDels2.push(d)
-    })
-  }
-
-  var buffer = Y.utils.globalRoom.buffers
-  for (var name in buffer) {
-    if (buffer[name].length > 0) {
-      // not all ops were transmitted..
-      debugger // eslint-disable-line
-    }
-  }
-
-  for (var uid = 0; uid < users.length; uid++) {
-    var u = users[uid]
-    u.db.requestTransaction(function * () {
-      var sv = yield * this.getStateVector()
-      for (var s of sv) {
-        yield * this.updateState(s.user)
-      }
-      // compare deleted ops against deleteStore
-      yield * this.os.iterate(this, null, null, function * (o) {
-        if (o.deleted === true) {
-          expect(yield * this.isDeleted(o.id)).toBeTruthy()
-        }
-      })
-      // compare deleteStore against deleted ops
-      var ds = []
-      yield * this.ds.iterate(this, null, null, function * (d) {
-        ds.push(d)
-      })
-      for (var j in ds) {
-        var d = ds[j]
-        for (var i = 0; i < d.len; i++) {
-          var o = yield * this.getInsertion([d.id[0], d.id[1] + i])
-          // gc'd or deleted
-          if (d.gc) {
-            expect(o).toBeFalsy()
-          } else {
-            expect(o.deleted).toBeTruthy()
-          }
-        }
-      }
-    })
-    // compare allDels tree
-    if (s1 == null) {
-      u.db.requestTransaction(function * () {
-        yield * t1.call(this)
-        yield * this.os.iterate(this, null, null, function * (o) {
-          o = Y.utils.copyObject(o)
-          delete o.origin
-          delete o.originOf
-          db1.push(o)
-        })
-      })
-    } else {
-      u.db.requestTransaction(function * () {
-        yield * t2.call(this)
-        var db2 = []
-        yield * this.os.iterate(this, null, null, function * (o) {
-          o = Y.utils.copyObject(o)
-          delete o.origin
-          delete o.originOf
-          db2.push(o)
-        })
-        expect(s1).toEqual(s2)
-        expect(allDels1).toEqual(allDels2) // inner structure
-        expect(ds1).toEqual(ds2) // exported structure
-        db2.forEach((o, i) => {
-          expect(db1[i]).toEqual(o)
-        })
-      })
-    }
-    yield u.db.whenTransactionsFinished()
-  }
-})
-
-g.createUsers = async(function * createUsers (self, numberOfUsers, database, initType) {
-  if (Y.utils.globalRoom.users[0] != null) {
-    yield Y.utils.globalRoom.flushAll()
-  }
-  // destroy old users
-  for (var u in Y.utils.globalRoom.users) {
-    Y.utils.globalRoom.users[u].y.destroy()
-  }
-  self.users = null
-
-  var promises = []
-  for (var i = 0; i < numberOfUsers; i++) {
-    promises.push(Y({
-      db: {
-        name: database,
-        namespace: 'User ' + i,
-        cleanStart: true,
-        gcTimeout: -1,
-        gc: true,
-        repairCheckInterval: -1
-      },
-      connector: {
-        name: 'Test',
-        debug: false
-      },
-      share: {
-        root: initType || 'Map'
-      }
-    }))
-  }
-  self.users = yield Promise.all(promises)
-  self.types = self.users.map(function (u) { return u.share.root })
-  return self.users
-})
-
-/*
-  Until async/await arrives in js, we use this function to wait for promises
-  by yielding them.
-*/
-function async (makeGenerator) {
-  return function (arg) {
-    var generator = makeGenerator.apply(this, arguments)
-
-    function handle (result) {
-      if (result.done) return Promise.resolve(result.value)
-
-      return Promise.resolve(result.value).then(function (res) {
-        return handle(generator.next(res))
-      }, function (err) {
-        return handle(generator.throw(err))
-      })
-    }
-    try {
-      return handle(generator.next())
-    } catch (ex) {
-      generator.throw(ex)
-      // return Promise.reject(ex)
-    }
-  }
-}
-g.async = async
-
-function logUsers (self) {
-  if (self.constructor === Array) {
-    self = {users: self}
-  }
-  self.users[0].db.logTable()
-  self.users[1].db.logTable()
-  self.users[2].db.logTable()
-}
-
-g.logUsers = logUsers

src/Struct.js

@@ -1,414 +0,0 @@
-/* @flow */
-'use strict'
-
-/*
- An operation also defines the structure of a type. This is why operation and
- structure are used interchangeably here.
-
- It must be of the type Object. I hope to achieve some performance
- improvements when working on databases that support the json format.
-
- An operation must have the following properties:
-
- * encode
-     - Encode the structure in a readable format (preferably string- todo)
- * decode (todo)
-     - decode structure to json
- * execute
-     - Execute the semantics of an operation.
- * requiredOps
-     - Operations that are required to execute this operation.
-*/
-export default function extendStruct (Y) {
-  var Struct = {
-    /* This is the only operation that is actually not a structure, because
-    it is not stored in the OS. This is why it _does not_ have an id
-
-    op = {
-      target: Id
-    }
-    */
-    Delete: {
-      encode: function (op) {
-        return {
-          target: op.target,
-          length: op.length || 0,
-          struct: 'Delete'
-        }
-      },
-      requiredOps: function (op) {
-        return [] // [op.target]
-      },
-      execute: function * (op) {
-        return yield * this.deleteOperation(op.target, op.length || 1)
-      }
-    },
-    Insert: {
-      /* {
-          content: [any],
-          opContent: Id,
-          id: Id,
-          left: Id,
-          origin: Id,
-          right: Id,
-          parent: Id,
-          parentSub: string (optional), // child of Map type
-        }
-      */
-      encode: function (op/* :Insertion */) /* :Insertion */ {
-        // TODO: you could not send the "left" property, then you also have to
-        // "op.left = null" in $execute or $decode
-        var e/* :any */ = {
-          id: op.id,
-          left: op.left,
-          right: op.right,
-          origin: op.origin,
-          parent: op.parent,
-          struct: op.struct
-        }
-        if (op.parentSub != null) {
-          e.parentSub = op.parentSub
-        }
-        if (op.hasOwnProperty('opContent')) {
-          e.opContent = op.opContent
-        } else {
-          e.content = op.content.slice()
-        }
-
-        return e
-      },
-      requiredOps: function (op) {
-        var ids = []
-        if (op.left != null) {
-          ids.push(op.left)
-        }
-        if (op.right != null) {
-          ids.push(op.right)
-        }
-        if (op.origin != null && !Y.utils.compareIds(op.left, op.origin)) {
-          ids.push(op.origin)
-        }
-        // if (op.right == null && op.left == null) {
-        ids.push(op.parent)
-
-        if (op.opContent != null) {
-          ids.push(op.opContent)
-        }
-        return ids
-      },
-      getDistanceToOrigin: function * (op) {
-        if (op.left == null) {
-          return 0
-        } else {
-          var d = 0
-          var o = yield * this.getInsertion(op.left)
-          while (!Y.utils.matchesId(o, op.origin)) {
-            d++
-            if (o.left == null) {
-              break
-            } else {
-              o = yield * this.getInsertion(o.left)
-            }
-          }
-          return d
-        }
-      },
-      /*
-      # $this has to find a unique position between origin and the next known character
-      # case 1: $origin equals $o.origin: the $creator parameter decides if left or right
-      #         let $OL= [o1,o2,o3,o4], whereby $this is to be inserted between o1 and o4
-      #         o2,o3 and o4 origin is 1 (the position of o2)
-      #         there is the case that $this.creator < o2.creator, but o3.creator < $this.creator
-      #         then o2 knows o3. Since on another client $OL could be [o1,o3,o4] the problem is complex
-      #         therefore $this would be always to the right of o3
-      # case 2: $origin < $o.origin
-      #         if current $this insert_position > $o origin: $this ins
-      #         else $insert_position will not change
-      #         (maybe we encounter case 1 later, then this will be to the right of $o)
-      # case 3: $origin > $o.origin
-      #         $this insert_position is to the left of $o (forever!)
-      */
-      execute: function * (op) {
-        var i // loop counter
-
-        // during this function some ops may get split into two pieces (e.g. with getInsertionCleanEnd)
-        // We try to merge them later, if possible
-        var tryToRemergeLater = []
-
-        if (op.origin != null) { // TODO: !== instead of !=
-          // we save in origin that op originates in it
-          // we need that later when we eventually garbage collect origin (see transaction)
-          var origin = yield * this.getInsertionCleanEnd(op.origin)
-          if (origin.originOf == null) {
-            origin.originOf = []
-          }
-          origin.originOf.push(op.id)
-          yield * this.setOperation(origin)
-          if (origin.right != null) {
-            tryToRemergeLater.push(origin.right)
-          }
-        }
-        var distanceToOrigin = i = yield * Struct.Insert.getDistanceToOrigin.call(this, op) // most cases: 0 (starts from 0)
-
-        // now we begin to insert op in the list of insertions..
-        var o
-        var parent
-        var start
-
-        // find o. o is the first conflicting operation
-        if (op.left != null) {
-          o = yield * this.getInsertionCleanEnd(op.left)
-          if (!Y.utils.compareIds(op.left, op.origin) && o.right != null) {
-            // only if not added previously
-            tryToRemergeLater.push(o.right)
-          }
-          o = (o.right == null) ? null : yield * this.getOperation(o.right)
-        } else { // left == null
-          parent = yield * this.getOperation(op.parent)
-          let startId = op.parentSub ? parent.map[op.parentSub] : parent.start
-          start = startId == null ? null : yield * this.getOperation(startId)
-          o = start
-        }
-
-        // make sure to split op.right if necessary (also add to tryCombineWithLeft)
-        if (op.right != null) {
-          tryToRemergeLater.push(op.right)
-          yield * this.getInsertionCleanStart(op.right)
-        }
-
-        // handle conflicts
-        while (true) {
-          if (o != null && !Y.utils.compareIds(o.id, op.right)) {
-            var oOriginDistance = yield * Struct.Insert.getDistanceToOrigin.call(this, o)
-            if (oOriginDistance === i) {
-              // case 1
-              if (o.id[0] < op.id[0]) {
-                op.left = Y.utils.getLastId(o)
-                distanceToOrigin = i + 1 // just ignore o.content.length, doesn't make a difference
-              }
-            } else if (oOriginDistance < i) {
-              // case 2
-              if (i - distanceToOrigin <= oOriginDistance) {
-                op.left = Y.utils.getLastId(o)
-                distanceToOrigin = i + 1 // just ignore o.content.length, doesn't make a difference
-              }
-            } else {
-              break
-            }
-            i++
-            if (o.right != null) {
-              o = yield * this.getInsertion(o.right)
-            } else {
-              o = null
-            }
-          } else {
-            break
-          }
-        }
-
-        // reconnect..
-        var left = null
-        var right = null
-        if (parent == null) {
-          parent = yield * this.getOperation(op.parent)
-        }
-
-        // reconnect left and set right of op
-        if (op.left != null) {
-          left = yield * this.getInsertion(op.left)
-          // link left
-          op.right = left.right
-          left.right = op.id
-
-          yield * this.setOperation(left)
-        } else {
-          // set op.right from parent, if necessary
-          op.right = op.parentSub ? parent.map[op.parentSub] || null : parent.start
-        }
-        // reconnect right
-        if (op.right != null) {
-          // TODO: wanna connect right too?
-          right = yield * this.getOperation(op.right)
-          right.left = Y.utils.getLastId(op)
-
-          // if right exists, and it is supposed to be gc'd. Remove it from the gc
-          if (right.gc != null) {
-            if (right.content != null && right.content.length > 1) {
-              right = yield * this.getInsertionCleanEnd(right.id)
-            }
-            this.store.removeFromGarbageCollector(right)
-          }
-          yield * this.setOperation(right)
-        }
-
-        // update parents .map/start/end properties
-        if (op.parentSub != null) {
-          if (left == null) {
-            parent.map[op.parentSub] = op.id
-            yield * this.setOperation(parent)
-          }
-          // is a child of a map struct.
-          // Then also make sure that only the most left element is not deleted
-          // We do not call the type in this case (this is what the third parameter is for)
-          if (op.right != null) {
-            yield * this.deleteOperation(op.right, 1, true)
-          }
-          if (op.left != null) {
-            yield * this.deleteOperation(op.id, 1, true)
-          }
-        } else {
-          if (right == null || left == null) {
-            if (right == null) {
-              parent.end = Y.utils.getLastId(op)
-            }
-            if (left == null) {
-              parent.start = op.id
-            }
-            yield * this.setOperation(parent)
-          }
-        }
-
-        // try to merge original op.left and op.origin
-        for (i = 0; i < tryToRemergeLater.length; i++) {
-          var m = yield * this.getOperation(tryToRemergeLater[i])
-          yield * this.tryCombineWithLeft(m)
-        }
-      }
-    },
-    List: {
-      /*
-      {
-        start: null,
-        end: null,
-        struct: "List",
-        type: "",
-        id: this.os.getNextOpId(1)
-      }
-      */
-      create: function (id) {
-        return {
-          start: null,
-          end: null,
-          struct: 'List',
-          id: id
-        }
-      },
-      encode: function (op) {
-        var e = {
-          struct: 'List',
-          id: op.id,
-          type: op.type
-        }
-        if (op.requires != null) {
-          e.requires = op.requires
-        }
-        if (op.info != null) {
-          e.info = op.info
-        }
-        return e
-      },
-      requiredOps: function () {
-        /*
-        var ids = []
-        if (op.start != null) {
-          ids.push(op.start)
-        }
-        if (op.end != null){
-          ids.push(op.end)
-        }
-        return ids
-        */
-        return []
-      },
-      execute: function * (op) {
-        op.start = null
-        op.end = null
-      },
-      ref: function * (op, pos) {
-        if (op.start == null) {
-          return null
-        }
-        var res = null
-        var o = yield * this.getOperation(op.start)
-
-        while (true) {
-          if (!o.deleted) {
-            res = o
-            pos--
-          }
-          if (pos >= 0 && o.right != null) {
-            o = yield * this.getOperation(o.right)
-          } else {
-            break
-          }
-        }
-        return res
-      },
-      map: function * (o, f) {
-        o = o.start
-        var res = []
-        while (o != null) { // TODO: change to != (at least some convention)
-          var operation = yield * this.getOperation(o)
-          if (!operation.deleted) {
-            res.push(f(operation))
-          }
-          o = operation.right
-        }
-        return res
-      }
-    },
-    Map: {
-      /*
-        {
-          map: {},
-          struct: "Map",
-          type: "",
-          id: this.os.getNextOpId(1)
-        }
-      */
-      create: function (id) {
-        return {
-          id: id,
-          map: {},
-          struct: 'Map'
-        }
-      },
-      encode: function (op) {
-        var e = {
-          struct: 'Map',
-          type: op.type,
-          id: op.id,
-          map: {} // overwrite map!!
-        }
-        if (op.requires != null) {
-          e.requires = op.requires
-        }
-        if (op.info != null) {
-          e.info = op.info
-        }
-        return e
-      },
-      requiredOps: function () {
-        return []
-      },
-      execute: function * () {},
-      /*
-        Get a property by name
-      */
-      get: function * (op, name) {
-        var oid = op.map[name]
-        if (oid != null) {
-          var res = yield * this.getOperation(oid)
-          if (res == null || res.deleted) {
-            return void 0
-          } else if (res.opContent == null) {
-            return res.content[0]
-          } else {
-            return yield * this.getType(res.opContent)
-          }
-        }
-      }
-    }
-  }
-  Y.Struct = Struct
-}

src/Utils.js

@@ -1,825 +0,0 @@
-/*
-  EventHandler is an helper class for constructing custom types.
-
-  Why: When constructing custom types, you sometimes want your types to work
-  synchronous: E.g.
-  ``` Synchronous
-    mytype.setSomething("yay")
-    mytype.getSomething() === "yay"
-  ```
-  versus
-  ``` Asynchronous
-    mytype.setSomething("yay")
-    mytype.getSomething() === undefined
-    mytype.waitForSomething().then(function(){
-      mytype.getSomething() === "yay"
-    })
-  ```
-
-  The structures usually work asynchronously (you have to wait for the
-  database request to finish). EventHandler helps you to make your type
-  synchronous.
-*/
-
-export default function Utils (Y) {
-  Y.utils = {}
-
-  Y.utils.bubbleEvent = function (type, event) {
-    type.eventHandler.callEventListeners(event)
-    event.path = []
-    while (type != null && type._deepEventHandler != null) {
-      type._deepEventHandler.callEventListeners(event)
-      var parent = null
-      if (type._parent != null) {
-        parent = type.os.getType(type._parent)
-      }
-      if (parent != null && parent._getPathToChild != null) {
-        event.path = [parent._getPathToChild(type._model)].concat(event.path)
-        type = parent
-      } else {
-        type = null
-      }
-    }
-  }
-
-  class NamedEventHandler {
-    constructor () {
-      this._eventListener = {}
-    }
-    on (name, f) {
-      if (this._eventListener[name] == null) {
-        this._eventListener[name] = []
-      }
-      this._eventListener[name].push(f)
-    }
-    off (name, f) {
-      if (name == null || f == null) {
-        throw new Error('You must specify event name and function!')
-      }
-      let listener = this._eventListener[name] || []
-      this._eventListener[name] = listener.filter(e => e !== f)
-    }
-    emit (name, value) {
-      (this._eventListener[name] || []).forEach(l => l(value))
-    }
-    destroy () {
-      this._eventListener = null
-    }
-  }
-  Y.utils.NamedEventHandler = NamedEventHandler
-
-  class EventListenerHandler {
-    constructor () {
-      this.eventListeners = []
-    }
-    destroy () {
-      this.eventListeners = null
-    }
-     /*
-      Basic event listener boilerplate...
-    */
-    addEventListener (f) {
-      this.eventListeners.push(f)
-    }
-    removeEventListener (f) {
-      this.eventListeners = this.eventListeners.filter(function (g) {
-        return f !== g
-      })
-    }
-    removeAllEventListeners () {
-      this.eventListeners = []
-    }
-    callEventListeners (event) {
-      for (var i = 0; i < this.eventListeners.length; i++) {
-        try {
-          var _event = {}
-          for (var name in event) {
-            _event[name] = event[name]
-          }
-          this.eventListeners[i](_event)
-        } catch (e) {
-          /*
-            Your observer threw an error. This error was caught so that Yjs
-            can ensure data consistency! In order to debug this error you
-            have to check "Pause On Caught Exceptions" in developer tools.
-          */
-          console.error(e)
-        }
-      }
-    }
-  }
-  Y.utils.EventListenerHandler = EventListenerHandler
-
-  class EventHandler extends EventListenerHandler {
-    /* ::
-    waiting: Array<Insertion | Deletion>;
-    awaiting: number;
-    onevent: Function;
-    eventListeners: Array<Function>;
-    */
-    /*
-      onevent: is called when the structure changes.
-
-      Note: "awaiting opertations" is used to denote operations that were
-      prematurely called. Events for received operations can not be executed until
-      all prematurely called operations were executed ("waiting operations")
-    */
-    constructor (onevent /* : Function */) {
-      super()
-      this.waiting = []
-      this.awaiting = 0
-      this.onevent = onevent
-    }
-    destroy () {
-      super.destroy()
-      this.waiting = null
-      this.onevent = null
-    }
-    /*
-      Call this when a new operation arrives. It will be executed right away if
-      there are no waiting operations, that you prematurely executed
-    */
-    receivedOp (op) {
-      if (this.awaiting <= 0) {
-        this.onevent(op)
-      } else if (op.struct === 'Delete') {
-        var self = this
-        var checkDelete = function checkDelete (d) {
-          if (d.length == null) {
-            throw new Error('This shouldn\'t happen! d.length must be defined!')
-          }
-          // we check if o deletes something in self.waiting
-          // if so, we remove the deleted operation
-          for (var w = 0; w < self.waiting.length; w++) {
-            var i = self.waiting[w]
-            if (i.struct === 'Insert' && i.id[0] === d.target[0]) {
-              var iLength = i.hasOwnProperty('content') ? i.content.length : 1
-              var dStart = d.target[1]
-              var dEnd = d.target[1] + (d.length || 1)
-              var iStart = i.id[1]
-              var iEnd = i.id[1] + iLength
-              // Check if they don't overlap
-              if (iEnd <= dStart || dEnd <= iStart) {
-                // no overlapping
-                continue
-              }
-              // we check all overlapping cases. All cases:
-              /*
-                1)  iiiii
-                      ddddd
-                    --> modify i and d
-                2)  iiiiiii
-                      ddddd
-                    --> modify i, remove d
-                3)  iiiiiii
-                      ddd
-                    --> remove d, modify i, and create another i (for the right hand side)
-                4)  iiiii
-                    ddddddd
-                    --> remove i, modify d
-                5)  iiiiiii
-                    ddddddd
-                    --> remove both i and d (**)
-                6)  iiiiiii
-                    ddddd
-                    --> modify i, remove d
-                7)    iii
-                    ddddddd
-                    --> remove i, create and apply two d with checkDelete(d) (**)
-                8)    iiiii
-                    ddddddd
-                    --> remove i, modify d (**)
-                9)    iiiii
-                    ddddd
-                    --> modify i and d
-                (**) (also check if i contains content or type)
-              */
-              // TODO: I left some debugger statements, because I want to debug all cases once in production. REMEMBER END TODO
-              if (iStart < dStart) {
-                if (dStart < iEnd) {
-                  if (iEnd < dEnd) {
-                    // Case 1
-                    // remove the right part of i's content
-                    i.content.splice(dStart - iStart)
-                    // remove the start of d's deletion
-                    d.length = dEnd - iEnd
-                    d.target = [d.target[0], iEnd]
-                    continue
-                  } else if (iEnd === dEnd) {
-                    // Case 2
-                    i.content.splice(dStart - iStart)
-                    // remove d, we do that by simply ending this function
-                    return
-                  } else { // (dEnd < iEnd)
-                    // Case 3
-                    var newI = {
-                      id: [i.id[0], dEnd],
-                      content: i.content.slice(dEnd - iStart),
-                      struct: 'Insert'
-                    }
-                    self.waiting.push(newI)
-                    i.content.splice(dStart - iStart)
-                    return
-                  }
-                }
-              } else if (dStart === iStart) {
-                if (iEnd < dEnd) {
-                  // Case 4
-                  d.length = dEnd - iEnd
-                  d.target = [d.target[0], iEnd]
-                  i.content = []
-                  continue
-                } else if (iEnd === dEnd) {
-                  // Case 5
-                  self.waiting.splice(w, 1)
-                  return
-                } else { // (dEnd < iEnd)
-                  // Case 6
-                  i.content = i.content.slice(dEnd - iStart)
-                  i.id = [i.id[0], dEnd]
-                  return
-                }
-              } else { // (dStart < iStart)
-                if (iStart < dEnd) {
-                  // they overlap
-                  /*
-                  7)    iii
-                      ddddddd
-                      --> remove i, create and apply two d with checkDelete(d) (**)
-                  8)    iiiii
-                      ddddddd
-                      --> remove i, modify d (**)
-                  9)    iiiii
-                      ddddd
-                      --> modify i and d
-                  */
-                  if (iEnd < dEnd) {
-                    // Case 7
-                    // debugger // TODO: You did not test this case yet!!!! (add the debugger here)
-                    self.waiting.splice(w, 1)
-                    checkDelete({
-                      target: [d.target[0], dStart],
-                      length: iStart - dStart,
-                      struct: 'Delete'
-                    })
-                    checkDelete({
-                      target: [d.target[0], iEnd],
-                      length: iEnd - dEnd,
-                      struct: 'Delete'
-                    })
-                    return
-                  } else if (iEnd === dEnd) {
-                    // Case 8
-                    self.waiting.splice(w, 1)
-                    w--
-                    d.length -= iLength
-                    continue
-                  } else { // dEnd < iEnd
-                    // Case 9
-                    d.length = iStart - dStart
-                    i.content.splice(0, dEnd - iStart)
-                    i.id = [i.id[0], dEnd]
-                    continue
-                  }
-                }
-              }
-            }
-          }
-          // finished with remaining operations
-          self.waiting.push(d)
-        }
-        if (op.key == null) {
-          // deletes in list
-          checkDelete(op)
-        } else {
-          // deletes in map
-          this.waiting.push(op)
-        }
-      } else {
-        this.waiting.push(op)
-      }
-    }
-    /*
-      You created some operations, and you want the `onevent` function to be
-      called right away. Received operations will not be executed untill all
-      prematurely called operations are executed
-    */
-    awaitAndPrematurelyCall (ops) {
-      this.awaiting++
-      ops.map(Y.utils.copyOperation).forEach(this.onevent)
-    }
-    * awaitOps (transaction, f, args) {
-      function notSoSmartSort (array) {
-        // this function sorts insertions in a executable order
-        var result = []
-        while (array.length > 0) {
-          for (var i = 0; i < array.length; i++) {
-            var independent = true
-            for (var j = 0; j < array.length; j++) {
-              if (Y.utils.matchesId(array[j], array[i].left)) {
-                // array[i] depends on array[j]
-                independent = false
-                break
-              }
-            }
-            if (independent) {
-              result.push(array.splice(i, 1)[0])
-              i--
-            }
-          }
-        }
-        return result
-      }
-      var before = this.waiting.length
-      // somehow create new operations
-      yield * f.apply(transaction, args)
-      // remove all appended ops / awaited ops
-      this.waiting.splice(before)
-      if (this.awaiting > 0) this.awaiting--
-      // if there are no awaited ops anymore, we can update all waiting ops, and send execute them (if there are still no awaited ops)
-      if (this.awaiting === 0 && this.waiting.length > 0) {
-        // update all waiting ops
-        for (let i = 0; i < this.waiting.length; i++) {
-          var o = this.waiting[i]
-          if (o.struct === 'Insert') {
-            var _o = yield * transaction.getInsertion(o.id)
-            if (_o.parentSub != null && _o.left != null) {
-              // if o is an insertion of a map struc (parentSub is defined), then it shouldn't be necessary to compute left
-              this.waiting.splice(i, 1)
-              i-- // update index
-            } else if (!Y.utils.compareIds(_o.id, o.id)) {
-              // o got extended
-              o.left = [o.id[0], o.id[1] - 1]
-            } else if (_o.left == null) {
-              o.left = null
-            } else {
-              // find next undeleted op
-              var left = yield * transaction.getInsertion(_o.left)
-              while (left.deleted != null) {
-                if (left.left != null) {
-                  left = yield * transaction.getInsertion(left.left)
-                } else {
-                  left = null
-                  break
-                }
-              }
-              o.left = left != null ? Y.utils.getLastId(left) : null
-            }
-          }
-        }
-        // the previous stuff was async, so we have to check again!
-        // We also pull changes from the bindings, if there exists such a method, this could increase awaiting too
-        if (this._pullChanges != null) {
-          this._pullChanges()
-        }
-        if (this.awaiting === 0) {
-          // sort by type, execute inserts first
-          var ins = []
-          var dels = []
-          this.waiting.forEach(function (o) {
-            if (o.struct === 'Delete') {
-              dels.push(o)
-            } else {
-              ins.push(o)
-            }
-          })
-          this.waiting = []
-          // put in executable order
-          ins = notSoSmartSort(ins)
-          // this.onevent can trigger the creation of another operation
-          // -> check if this.awaiting increased & stop computation if it does
-          for (var i = 0; i < ins.length; i++) {
-            if (this.awaiting === 0) {
-              this.onevent(ins[i])
-            } else {
-              this.waiting = this.waiting.concat(ins.slice(i))
-              break
-            }
-          }
-          for (i = 0; i < dels.length; i++) {
-            if (this.awaiting === 0) {
-              this.onevent(dels[i])
-            } else {
-              this.waiting = this.waiting.concat(dels.slice(i))
-              break
-            }
-          }
-        }
-      }
-    }
-    // TODO: Remove awaitedInserts and awaitedDeletes in favor of awaitedOps, as they are deprecated and do not always work
-    // Do this in one of the coming releases that are breaking anyway
-    /*
-      Call this when you successfully awaited the execution of n Insert operations
-    */
-    awaitedInserts (n) {
-      var ops = this.waiting.splice(this.waiting.length - n)
-      for (var oid = 0; oid < ops.length; oid++) {
-        var op = ops[oid]
-        if (op.struct === 'Insert') {
-          for (var i = this.waiting.length - 1; i >= 0; i--) {
-            let w = this.waiting[i]
-            // TODO: do I handle split operations correctly here? Super unlikely, but yeah..
-            // Also: can this case happen? Can op be inserted in the middle of a larger op that is in $waiting?
-            if (w.struct === 'Insert') {
-              if (Y.utils.matchesId(w, op.left)) {
-                // include the effect of op in w
-                w.right = op.id
-                // exclude the effect of w in op
-                op.left = w.left
-              } else if (Y.utils.compareIds(w.id, op.right)) {
-                // similar..
-                w.left = Y.utils.getLastId(op)
-                op.right = w.right
-              }
-            }
-          }
-        } else {
-          throw new Error('Expected Insert Operation!')
-        }
-      }
-      this._tryCallEvents(n)
-    }
-    /*
-      Call this when you successfully awaited the execution of n Delete operations
-    */
-    awaitedDeletes (n, newLeft) {
-      var ops = this.waiting.splice(this.waiting.length - n)
-      for (var j = 0; j < ops.length; j++) {
-        var del = ops[j]
-        if (del.struct === 'Delete') {
-          if (newLeft != null) {
-            for (var i = 0; i < this.waiting.length; i++) {
-              let w = this.waiting[i]
-              // We will just care about w.left
-              if (w.struct === 'Insert' && Y.utils.compareIds(del.target, w.left)) {
-                w.left = newLeft
-              }
-            }
-          }
-        } else {
-          throw new Error('Expected Delete Operation!')
-        }
-      }
-      this._tryCallEvents(n)
-    }
-    /* (private)
-      Try to execute the events for the waiting operations
-    */
-    _tryCallEvents () {
-      function notSoSmartSort (array) {
-        var result = []
-        while (array.length > 0) {
-          for (var i = 0; i < array.length; i++) {
-            var independent = true
-            for (var j = 0; j < array.length; j++) {
-              if (Y.utils.matchesId(array[j], array[i].left)) {
-                // array[i] depends on array[j]
-                independent = false
-                break
-              }
-            }
-            if (independent) {
-              result.push(array.splice(i, 1)[0])
-              i--
-            }
-          }
-        }
-        return result
-      }
-      if (this.awaiting > 0) this.awaiting--
-      if (this.awaiting === 0 && this.waiting.length > 0) {
-        var ins = []
-        var dels = []
-        this.waiting.forEach(function (o) {
-          if (o.struct === 'Delete') {
-            dels.push(o)
-          } else {
-            ins.push(o)
-          }
-        })
-        ins = notSoSmartSort(ins)
-        ins.forEach(this.onevent)
-        dels.forEach(this.onevent)
-        this.waiting = []
-      }
-    }
-  }
-  Y.utils.EventHandler = EventHandler
-
-  /*
-    Default class of custom types!
-  */
-  class CustomType {
-    getPath () {
-      var parent = null
-      if (this._parent != null) {
-        parent = this.os.getType(this._parent)
-      }
-      if (parent != null && parent._getPathToChild != null) {
-        var firstKey = parent._getPathToChild(this._model)
-        var parentKeys = parent.getPath()
-        parentKeys.push(firstKey)
-        return parentKeys
-      } else {
-        return []
-      }
-    }
-  }
-  Y.utils.CustomType = CustomType
-
-  /*
-    A wrapper for the definition of a custom type.
-    Every custom type must have three properties:
-
-    * struct
-      - Structname of this type
-    * initType
-      - Given a model, creates a custom type
-    * class
-      - the constructor of the custom type (e.g. in order to inherit from a type)
-  */
-  class CustomTypeDefinition { // eslint-disable-line
-    /* ::
-    struct: any;
-    initType: any;
-    class: Function;
-    name: String;
-    */
-    constructor (def) {
-      if (def.struct == null ||
-        def.initType == null ||
-        def.class == null ||
-        def.name == null ||
-        def.createType == null
-      ) {
-        throw new Error('Custom type was not initialized correctly!')
-      }
-      this.struct = def.struct
-      this.initType = def.initType
-      this.createType = def.createType
-      this.class = def.class
-      this.name = def.name
-      if (def.appendAdditionalInfo != null) {
-        this.appendAdditionalInfo = def.appendAdditionalInfo
-      }
-      this.parseArguments = (def.parseArguments || function () {
-        return [this]
-      }).bind(this)
-      this.parseArguments.typeDefinition = this
-    }
-  }
-  Y.utils.CustomTypeDefinition = CustomTypeDefinition
-
-  Y.utils.isTypeDefinition = function isTypeDefinition (v) {
-    if (v != null) {
-      if (v instanceof Y.utils.CustomTypeDefinition) return [v]
-      else if (v.constructor === Array && v[0] instanceof Y.utils.CustomTypeDefinition) return v
-      else if (v instanceof Function && v.typeDefinition instanceof Y.utils.CustomTypeDefinition) return [v.typeDefinition]
-    }
-    return false
-  }
-
-  /*
-    Make a flat copy of an object
-    (just copy properties)
-  */
-  function copyObject (o) {
-    var c = {}
-    for (var key in o) {
-      c[key] = o[key]
-    }
-    return c
-  }
-  Y.utils.copyObject = copyObject
-
-  /*
-    Copy an operation, so that it can be manipulated.
-    Note: You must not change subproperties (except o.content)!
-  */
-  function copyOperation (o) {
-    o = copyObject(o)
-    if (o.content != null) {
-      o.content = o.content.map(function (c) { return c })
-    }
-    return o
-  }
-
-  Y.utils.copyOperation = copyOperation
-
-  /*
-    Defines a smaller relation on Id's
-  */
-  function smaller (a, b) {
-    return a[0] < b[0] || (a[0] === b[0] && (a[1] < b[1] || typeof a[1] < typeof b[1]))
-  }
-  Y.utils.smaller = smaller
-
-  function inDeletionRange (del, ins) {
-    return del.target[0] === ins[0] && del.target[1] <= ins[1] && ins[1] < del.target[1] + (del.length || 1)
-  }
-  Y.utils.inDeletionRange = inDeletionRange
-
-  function compareIds (id1, id2) {
-    if (id1 == null || id2 == null) {
-      return id1 === id2
-    } else {
-      return id1[0] === id2[0] && id1[1] === id2[1]
-    }
-  }
-  Y.utils.compareIds = compareIds
-
-  function matchesId (op, id) {
-    if (id == null || op == null) {
-      return id === op
-    } else {
-      if (id[0] === op.id[0]) {
-        if (op.content == null) {
-          return id[1] === op.id[1]
-        } else {
-          return id[1] >= op.id[1] && id[1] < op.id[1] + op.content.length
-        }
-      }
-    }
-    return false
-  }
-  Y.utils.matchesId = matchesId
-
-  function getLastId (op) {
-    if (op.content == null || op.content.length === 1) {
-      return op.id
-    } else {
-      return [op.id[0], op.id[1] + op.content.length - 1]
-    }
-  }
-  Y.utils.getLastId = getLastId
-
-  function createEmptyOpsArray (n) {
-    var a = new Array(n)
-    for (var i = 0; i < a.length; i++) {
-      a[i] = {
-        id: [null, null]
-      }
-    }
-    return a
-  }
-
-  function createSmallLookupBuffer (Store) {
-    /*
-      This buffer implements a very small buffer that temporarily stores operations
-      after they are read / before they are written.
-      The buffer basically implements FIFO. Often requested lookups will be re-queued every time they are looked up / written.
-
-      It can speed up lookups on Operation Stores and State Stores. But it does not require notable use of memory or processing power.
-
-      Good for os and ss, bot not for ds (because it often uses methods that require a flush)
-
-      I tried to optimize this for performance, therefore no highlevel operations.
-    */
-    class SmallLookupBuffer extends Store {
-      constructor (arg1, arg2) {
-        // super(...arguments) -- do this when this is supported by stable nodejs
-        super(arg1, arg2)
-        this.writeBuffer = createEmptyOpsArray(5)
-        this.readBuffer = createEmptyOpsArray(10)
-      }
-      * find (id, noSuperCall) {
-        var i, r
-        for (i = this.readBuffer.length - 1; i >= 0; i--) {
-          r = this.readBuffer[i]
-          // we don't have to use compareids, because id is always defined!
-          if (r.id[1] === id[1] && r.id[0] === id[0]) {
-            // found r
-            // move r to the end of readBuffer
-            for (; i < this.readBuffer.length - 1; i++) {
-              this.readBuffer[i] = this.readBuffer[i + 1]
-            }
-            this.readBuffer[this.readBuffer.length - 1] = r
-            return r
-          }
-        }
-        var o
-        for (i = this.writeBuffer.length - 1; i >= 0; i--) {
-          r = this.writeBuffer[i]
-          if (r.id[1] === id[1] && r.id[0] === id[0]) {
-            o = r
-            break
-          }
-        }
-        if (i < 0 && noSuperCall === undefined) {
-          // did not reach break in last loop
-          // read id and put it to the end of readBuffer
-          o = yield * super.find(id)
-        }
-        if (o != null) {
-          for (i = 0; i < this.readBuffer.length - 1; i++) {
-            this.readBuffer[i] = this.readBuffer[i + 1]
-          }
-          this.readBuffer[this.readBuffer.length - 1] = o
-        }
-        return o
-      }
-      * put (o) {
-        var id = o.id
-        var i, r // helper variables
-        for (i = this.writeBuffer.length - 1; i >= 0; i--) {
-          r = this.writeBuffer[i]
-          if (r.id[1] === id[1] && r.id[0] === id[0]) {
-            // is already in buffer
-            // forget r, and move o to the end of writeBuffer
-            for (; i < this.writeBuffer.length - 1; i++) {
-              this.writeBuffer[i] = this.writeBuffer[i + 1]
-            }
-            this.writeBuffer[this.writeBuffer.length - 1] = o
-            break
-          }
-        }
-        if (i < 0) {
-          // did not reach break in last loop
-          // write writeBuffer[0]
-          var write = this.writeBuffer[0]
-          if (write.id[0] !== null) {
-            yield * super.put(write)
-          }
-          // put o to the end of writeBuffer
-          for (i = 0; i < this.writeBuffer.length - 1; i++) {
-            this.writeBuffer[i] = this.writeBuffer[i + 1]
-          }
-          this.writeBuffer[this.writeBuffer.length - 1] = o
-        }
-        // check readBuffer for every occurence of o.id, overwrite if found
-        // whether found or not, we'll append o to the readbuffer
-        for (i = 0; i < this.readBuffer.length - 1; i++) {
-          r = this.readBuffer[i + 1]
-          if (r.id[1] === id[1] && r.id[0] === id[0]) {
-            this.readBuffer[i] = o
-          } else {
-            this.readBuffer[i] = r
-          }
-        }
-        this.readBuffer[this.readBuffer.length - 1] = o
-      }
-      * delete (id) {
-        var i, r
-        for (i = 0; i < this.readBuffer.length; i++) {
-          r = this.readBuffer[i]
-          if (r.id[1] === id[1] && r.id[0] === id[0]) {
-            this.readBuffer[i] = {
-              id: [null, null]
-            }
-          }
-        }
-        yield * this.flush()
-        yield * super.delete(id)
-      }
-      * findWithLowerBound (id) {
-        var o = yield * this.find(id, true)
-        if (o != null) {
-          return o
-        } else {
-          yield * this.flush()
-          return yield * super.findWithLowerBound.apply(this, arguments)
-        }
-      }
-      * findWithUpperBound (id) {
-        var o = yield * this.find(id, true)
-        if (o != null) {
-          return o
-        } else {
-          yield * this.flush()
-          return yield * super.findWithUpperBound.apply(this, arguments)
-        }
-      }
-      * findNext () {
-        yield * this.flush()
-        return yield * super.findNext.apply(this, arguments)
-      }
-      * findPrev () {
-        yield * this.flush()
-        return yield * super.findPrev.apply(this, arguments)
-      }
-      * iterate () {
-        yield * this.flush()
-        yield * super.iterate.apply(this, arguments)
-      }
-      * flush () {
-        for (var i = 0; i < this.writeBuffer.length; i++) {
-          var write = this.writeBuffer[i]
-          if (write.id[0] !== null) {
-            yield * super.put(write)
-            this.writeBuffer[i] = {
-              id: [null, null]
-            }
-          }
-        }
-      }
-    }
-    return SmallLookupBuffer
-  }
-  Y.utils.createSmallLookupBuffer = createSmallLookupBuffer
-
-  // Generates a unique id, for use as a user id.
-  // Thx to @jed for this script https://gist.github.com/jed/982883
-  function generateGuid(a){return a?(a^Math.random()*16>>a/4).toString(16):([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,generateGuid)} // eslint-disable-line
-  Y.utils.generateGuid = generateGuid
-}

src/index.js

@@ -0,0 +1,111 @@
+/** eslint-env browser */
+
+export {
+  Doc,
+  Transaction,
+  YArray as Array,
+  YMap as Map,
+  YText as Text,
+  YXmlText as XmlText,
+  YXmlHook as XmlHook,
+  YXmlElement as XmlElement,
+  YXmlFragment as XmlFragment,
+  YXmlEvent,
+  YMapEvent,
+  YArrayEvent,
+  YTextEvent,
+  YEvent,
+  Item,
+  AbstractStruct,
+  GC,
+  ContentBinary,
+  ContentDeleted,
+  ContentEmbed,
+  ContentFormat,
+  ContentJSON,
+  ContentAny,
+  ContentString,
+  ContentType,
+  AbstractType,
+  getTypeChildren,
+  createRelativePositionFromTypeIndex,
+  createRelativePositionFromJSON,
+  createAbsolutePositionFromRelativePosition,
+  compareRelativePositions,
+  AbsolutePosition,
+  RelativePosition,
+  ID,
+  createID,
+  compareIDs,
+  getState,
+  Snapshot,
+  createSnapshot,
+  createDeleteSet,
+  createDeleteSetFromStructStore,
+  cleanupYTextFormatting,
+  snapshot,
+  emptySnapshot,
+  findRootTypeKey,
+  findIndexSS,
+  getItem,
+  typeListToArraySnapshot,
+  typeMapGetSnapshot,
+  createDocFromSnapshot,
+  iterateDeletedStructs,
+  applyUpdate,
+  applyUpdateV2,
+  readUpdate,
+  readUpdateV2,
+  encodeStateAsUpdate,
+  encodeStateAsUpdateV2,
+  encodeStateVector,
+  UndoManager,
+  decodeSnapshot,
+  encodeSnapshot,
+  decodeSnapshotV2,
+  encodeSnapshotV2,
+  decodeStateVector,
+  logUpdate,
+  logUpdateV2,
+  relativePositionToJSON,
+  isDeleted,
+  isParentOf,
+  equalSnapshots,
+  PermanentUserData, // @TODO experimental
+  tryGc,
+  transact,
+  AbstractConnector,
+  logType,
+  mergeUpdates,
+  mergeUpdatesV2,
+  parseUpdateMeta,
+  parseUpdateMetaV2,
+  encodeStateVectorFromUpdate,
+  encodeStateVectorFromUpdateV2,
+  encodeRelativePosition,
+  decodeRelativePosition,
+  diffUpdate,
+  diffUpdateV2
+} from './internals.js'
+
+const glo = /** @type {any} */ (typeof window !== 'undefined'
+  ? window
+  : typeof global !== 'undefined' ? global : {})
+const importIdentifier = '__ $YJS$ __'
+
+if (glo[importIdentifier] === true) {
+  /**
+   * Dear reader of this warning message. Please take this seriously.
+   *
+   * If you see this message, please make sure that you only import one version of Yjs. In many cases,
+   * your package manager installs two versions of Yjs that are used by different packages within your project.
+   * Another reason for this message is that some parts of your project use the commonjs version of Yjs
+   * and others use the EcmaScript version of Yjs.
+   *
+   * This often leads to issues that are hard to debug. We often need to perform constructor checks,
+   * e.g. `struct instanceof GC`. If you imported different versions of Yjs, it is impossible for us to
+   * do the constructor checks anymore - which might break the CRDT algorithm.
+   */
+  console.warn('Yjs was already imported. Importing different versions of Yjs often leads to issues.')
+}
+glo[importIdentifier] = true

src/internals.js

@@ -0,0 +1,43 @@
+
+export * from './utils/AbstractConnector.js'
+export * from './utils/DeleteSet.js'
+export * from './utils/Doc.js'
+export * from './utils/UpdateDecoder.js'
+export * from './utils/UpdateEncoder.js'
+export * from './utils/encoding.js'
+export * from './utils/EventHandler.js'
+export * from './utils/ID.js'
+export * from './utils/isParentOf.js'
+export * from './utils/logging.js'
+export * from './utils/PermanentUserData.js'
+export * from './utils/RelativePosition.js'
+export * from './utils/Snapshot.js'
+export * from './utils/StructStore.js'
+export * from './utils/Transaction.js'
+export * from './utils/UndoManager.js'
+export * from './utils/updates.js'
+export * from './utils/YEvent.js'
+
+export * from './types/AbstractType.js'
+export * from './types/YArray.js'
+export * from './types/YMap.js'
+export * from './types/YText.js'
+export * from './types/YXmlFragment.js'
+export * from './types/YXmlElement.js'
+export * from './types/YXmlEvent.js'
+export * from './types/YXmlHook.js'
+export * from './types/YXmlText.js'
+
+export * from './structs/AbstractStruct.js'
+export * from './structs/GC.js'
+export * from './structs/ContentBinary.js'
+export * from './structs/ContentDeleted.js'
+export * from './structs/ContentDoc.js'
+export * from './structs/ContentEmbed.js'
+export * from './structs/ContentFormat.js'
+export * from './structs/ContentJSON.js'
+export * from './structs/ContentAny.js'
+export * from './structs/ContentString.js'
+export * from './structs/ContentType.js'
+export * from './structs/Item.js'
+export * from './structs/Skip.js'

src/structs/AbstractStruct.js

@@ -0,0 +1,52 @@
+
+import {
+  UpdateEncoderV1, UpdateEncoderV2, ID, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+
+export class AbstractStruct {
+  /**
+   * @param {ID} id
+   * @param {number} length
+   */
+  constructor (id, length) {
+    this.id = id
+    this.length = length
+  }
+
+  /**
+   * @type {boolean}
+   */
+  get deleted () {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * Merge this struct with the item to the right.
+   * This method is already assuming that `this.id.clock + this.length === this.id.clock`.
+   * Also this method does *not* remove right from StructStore!
+   * @param {AbstractStruct} right
+   * @return {boolean} wether this merged with right
+   */
+  mergeWith (right) {
+    return false
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder The encoder to write data to.
+   * @param {number} offset
+   * @param {number} encodingRef
+   */
+  write (encoder, offset, encodingRef) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {number} offset
+   */
+  integrate (transaction, offset) {
+    throw error.methodUnimplemented()
+  }
+}

src/structs/ContentAny.js

@@ -0,0 +1,108 @@
+import {
+  UpdateEncoderV1, UpdateEncoderV2, UpdateDecoderV1, UpdateDecoderV2, Transaction, Item, StructStore // eslint-disable-line
+} from '../internals.js'
+
+export class ContentAny {
+  /**
+   * @param {Array<any>} arr
+   */
+  constructor (arr) {
+    /**
+     * @type {Array<any>}
+     */
+    this.arr = arr
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.arr.length
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return this.arr
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+
+  /**
+   * @return {ContentAny}
+   */
+  copy () {
+    return new ContentAny(this.arr)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentAny}
+   */
+  splice (offset) {
+    const right = new ContentAny(this.arr.slice(offset))
+    this.arr = this.arr.slice(0, offset)
+    return right
+  }
+
+  /**
+   * @param {ContentAny} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.arr = this.arr.concat(right.arr)
+    return true
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    const len = this.arr.length
+    encoder.writeLen(len - offset)
+    for (let i = offset; i < len; i++) {
+      const c = this.arr[i]
+      encoder.writeAny(c)
+    }
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 8
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentAny}
+ */
+export const readContentAny = decoder => {
+  const len = decoder.readLen()
+  const cs = []
+  for (let i = 0; i < len; i++) {
+    cs.push(decoder.readAny())
+  }
+  return new ContentAny(cs)
+}

src/structs/ContentBinary.js

@@ -0,0 +1,92 @@
+import {
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Item, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+
+export class ContentBinary {
+  /**
+   * @param {Uint8Array} content
+   */
+  constructor (content) {
+    this.content = content
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [this.content]
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+
+  /**
+   * @return {ContentBinary}
+   */
+  copy () {
+    return new ContentBinary(this.content)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentBinary}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {ContentBinary} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeBuf(this.content)
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 3
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2 } decoder
+ * @return {ContentBinary}
+ */
+export const readContentBinary = decoder => new ContentBinary(decoder.readBuf())

src/structs/ContentDeleted.js

@@ -0,0 +1,101 @@
+
+import {
+  addToDeleteSet,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Item, Transaction // eslint-disable-line
+} from '../internals.js'
+
+export class ContentDeleted {
+  /**
+   * @param {number} len
+   */
+  constructor (len) {
+    this.len = len
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.len
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return []
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return false
+  }
+
+  /**
+   * @return {ContentDeleted}
+   */
+  copy () {
+    return new ContentDeleted(this.len)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentDeleted}
+   */
+  splice (offset) {
+    const right = new ContentDeleted(this.len - offset)
+    this.len = offset
+    return right
+  }
+
+  /**
+   * @param {ContentDeleted} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.len += right.len
+    return true
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    addToDeleteSet(transaction.deleteSet, item.id.client, item.id.clock, this.len)
+    item.markDeleted()
+  }
+
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeLen(this.len - offset)
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 1
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {UpdateDecoderV1 | UpdateDecoderV2 } decoder
+ * @return {ContentDeleted}
+ */
+export const readContentDeleted = decoder => new ContentDeleted(decoder.readLen())

src/structs/ContentDoc.js

@@ -0,0 +1,135 @@
+
+import {
+  Doc, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Transaction, Item // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+
+/**
+ * @private
+ */
+export class ContentDoc {
+  /**
+   * @param {Doc} doc
+   */
+  constructor (doc) {
+    if (doc._item) {
+      console.error('This document was already integrated as a sub-document. You should create a second instance instead with the same guid.')
+    }
+    /**
+     * @type {Doc}
+     */
+    this.doc = doc
+    /**
+     * @type {any}
+     */
+    const opts = {}
+    this.opts = opts
+    if (!doc.gc) {
+      opts.gc = false
+    }
+    if (doc.autoLoad) {
+      opts.autoLoad = true
+    }
+    if (doc.meta !== null) {
+      opts.meta = doc.meta
+    }
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [this.doc]
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+
+  /**
+   * @return {ContentDoc}
+   */
+  copy () {
+    return new ContentDoc(this.doc)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentDoc}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {ContentDoc} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    // this needs to be reflected in doc.destroy as well
+    this.doc._item = item
+    transaction.subdocsAdded.add(this.doc)
+    if (this.doc.shouldLoad) {
+      transaction.subdocsLoaded.add(this.doc)
+    }
+  }
+
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {
+    if (transaction.subdocsAdded.has(this.doc)) {
+      transaction.subdocsAdded.delete(this.doc)
+    } else {
+      transaction.subdocsRemoved.add(this.doc)
+    }
+  }
+
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) { }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeString(this.doc.guid)
+    encoder.writeAny(this.opts)
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 9
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentDoc}
+ */
+export const readContentDoc = decoder => new ContentDoc(new Doc({ guid: decoder.readString(), ...decoder.readAny() }))

src/structs/ContentEmbed.js

@@ -0,0 +1,98 @@
+
+import {
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Item, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+
+/**
+ * @private
+ */
+export class ContentEmbed {
+  /**
+   * @param {Object} embed
+   */
+  constructor (embed) {
+    this.embed = embed
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [this.embed]
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+
+  /**
+   * @return {ContentEmbed}
+   */
+  copy () {
+    return new ContentEmbed(this.embed)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentEmbed}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {ContentEmbed} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeJSON(this.embed)
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 5
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentEmbed}
+ */
+export const readContentEmbed = decoder => new ContentEmbed(decoder.readJSON())

src/structs/ContentFormat.js

@@ -0,0 +1,103 @@
+
+import {
+  AbstractType, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Item, StructStore, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+
+/**
+ * @private
+ */
+export class ContentFormat {
+  /**
+   * @param {string} key
+   * @param {Object} value
+   */
+  constructor (key, value) {
+    this.key = key
+    this.value = value
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return []
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return false
+  }
+
+  /**
+   * @return {ContentFormat}
+   */
+  copy () {
+    return new ContentFormat(this.key, this.value)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentFormat}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {ContentFormat} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    // @todo searchmarker are currently unsupported for rich text documents
+    /** @type {AbstractType<any>} */ (item.parent)._searchMarker = null
+  }
+
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeKey(this.key)
+    encoder.writeJSON(this.value)
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 6
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentFormat}
+ */
+export const readContentFormat = decoder => new ContentFormat(decoder.readString(), decoder.readJSON())

src/structs/ContentJSON.js

@@ -0,0 +1,118 @@
+import {
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Transaction, Item, StructStore // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * @private
+ */
+export class ContentJSON {
+  /**
+   * @param {Array<any>} arr
+   */
+  constructor (arr) {
+    /**
+     * @type {Array<any>}
+     */
+    this.arr = arr
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.arr.length
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return this.arr
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+
+  /**
+   * @return {ContentJSON}
+   */
+  copy () {
+    return new ContentJSON(this.arr)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentJSON}
+   */
+  splice (offset) {
+    const right = new ContentJSON(this.arr.slice(offset))
+    this.arr = this.arr.slice(0, offset)
+    return right
+  }
+
+  /**
+   * @param {ContentJSON} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.arr = this.arr.concat(right.arr)
+    return true
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    const len = this.arr.length
+    encoder.writeLen(len - offset)
+    for (let i = offset; i < len; i++) {
+      const c = this.arr[i]
+      encoder.writeString(c === undefined ? 'undefined' : JSON.stringify(c))
+    }
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 2
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentJSON}
+ */
+export const readContentJSON = decoder => {
+  const len = decoder.readLen()
+  const cs = []
+  for (let i = 0; i < len; i++) {
+    const c = decoder.readString()
+    if (c === 'undefined') {
+      cs.push(undefined)
+    } else {
+      cs.push(JSON.parse(c))
+    }
+  }
+  return new ContentJSON(cs)
+}

src/structs/ContentString.js

@@ -0,0 +1,112 @@
+import {
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Transaction, Item, StructStore // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * @private
+ */
+export class ContentString {
+  /**
+   * @param {string} str
+   */
+  constructor (str) {
+    /**
+     * @type {string}
+     */
+    this.str = str
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return this.str.length
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return this.str.split('')
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+
+  /**
+   * @return {ContentString}
+   */
+  copy () {
+    return new ContentString(this.str)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentString}
+   */
+  splice (offset) {
+    const right = new ContentString(this.str.slice(offset))
+    this.str = this.str.slice(0, offset)
+
+    // Prevent encoding invalid documents because of splitting of surrogate pairs: https://github.com/yjs/yjs/issues/248
+    const firstCharCode = this.str.charCodeAt(offset - 1)
+    if (firstCharCode >= 0xD800 && firstCharCode <= 0xDBFF) {
+      // Last character of the left split is the start of a surrogate utf16/ucs2 pair.
+      // We don't support splitting of surrogate pairs because this may lead to invalid documents.
+      // Replace the invalid character with a unicode replacement character (<28> / U+FFFD)
+      this.str = this.str.slice(0, offset - 1) + '<27>'
+      // replace right as well
+      right.str = '<27>' + right.str.slice(1)
+    }
+    return right
+  }
+
+  /**
+   * @param {ContentString} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    this.str += right.str
+    return true
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {}
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {}
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeString(offset === 0 ? this.str : this.str.slice(offset))
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 4
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentString}
+ */
+export const readContentString = decoder => new ContentString(decoder.readString())

src/structs/ContentType.js

@@ -0,0 +1,172 @@
+
+import {
+  readYArray,
+  readYMap,
+  readYText,
+  readYXmlElement,
+  readYXmlFragment,
+  readYXmlHook,
+  readYXmlText,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Transaction, Item, YEvent, AbstractType // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+
+/**
+ * @type {Array<function(UpdateDecoderV1 | UpdateDecoderV2):AbstractType<any>>}
+ * @private
+ */
+export const typeRefs = [
+  readYArray,
+  readYMap,
+  readYText,
+  readYXmlElement,
+  readYXmlFragment,
+  readYXmlHook,
+  readYXmlText
+]
+
+export const YArrayRefID = 0
+export const YMapRefID = 1
+export const YTextRefID = 2
+export const YXmlElementRefID = 3
+export const YXmlFragmentRefID = 4
+export const YXmlHookRefID = 5
+export const YXmlTextRefID = 6
+
+/**
+ * @private
+ */
+export class ContentType {
+  /**
+   * @param {AbstractType<YEvent>} type
+   */
+  constructor (type) {
+    /**
+     * @type {AbstractType<any>}
+     */
+    this.type = type
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [this.type]
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return true
+  }
+
+  /**
+   * @return {ContentType}
+   */
+  copy () {
+    return new ContentType(this.type._copy())
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentType}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {ContentType} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    this.type._integrate(transaction.doc, item)
+  }
+
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {
+    let item = this.type._start
+    while (item !== null) {
+      if (!item.deleted) {
+        item.delete(transaction)
+      } else {
+        // Whis will be gc'd later and we want to merge it if possible
+        // We try to merge all deleted items after each transaction,
+        // but we have no knowledge about that this needs to be merged
+        // since it is not in transaction.ds. Hence we add it to transaction._mergeStructs
+        transaction._mergeStructs.push(item)
+      }
+      item = item.right
+    }
+    this.type._map.forEach(item => {
+      if (!item.deleted) {
+        item.delete(transaction)
+      } else {
+        // same as above
+        transaction._mergeStructs.push(item)
+      }
+    })
+    transaction.changed.delete(this.type)
+  }
+
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {
+    let item = this.type._start
+    while (item !== null) {
+      item.gc(store, true)
+      item = item.right
+    }
+    this.type._start = null
+    this.type._map.forEach(/** @param {Item | null} item */ (item) => {
+      while (item !== null) {
+        item.gc(store, true)
+        item = item.left
+      }
+    })
+    this.type._map = new Map()
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    this.type._write(encoder)
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 7
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentType}
+ */
+export const readContentType = decoder => new ContentType(typeRefs[decoder.readTypeRef()](decoder))

src/structs/GC.js

@@ -0,0 +1,61 @@
+
+import {
+  AbstractStruct,
+  addStruct,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, StructStore, Transaction, ID // eslint-disable-line
+} from '../internals.js'
+
+export const structGCRefNumber = 0
+
+/**
+ * @private
+ */
+export class GC extends AbstractStruct {
+  get deleted () {
+    return true
+  }
+
+  delete () {}
+
+  /**
+   * @param {GC} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    if (this.constructor !== right.constructor) {
+      return false
+    }
+    this.length += right.length
+    return true
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {number} offset
+   */
+  integrate (transaction, offset) {
+    if (offset > 0) {
+      this.id.clock += offset
+      this.length -= offset
+    }
+    addStruct(transaction.doc.store, this)
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeInfo(structGCRefNumber)
+    encoder.writeLen(this.length - offset)
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {StructStore} store
+   * @return {null | number}
+   */
+  getMissing (transaction, store) {
+    return null
+  }
+}

src/structs/Item.js

@@ -0,0 +1,806 @@
+
+import {
+  GC,
+  getState,
+  AbstractStruct,
+  replaceStruct,
+  addStruct,
+  addToDeleteSet,
+  findRootTypeKey,
+  compareIDs,
+  getItem,
+  getItemCleanEnd,
+  getItemCleanStart,
+  readContentDeleted,
+  readContentBinary,
+  readContentJSON,
+  readContentAny,
+  readContentString,
+  readContentEmbed,
+  readContentDoc,
+  createID,
+  readContentFormat,
+  readContentType,
+  addChangedTypeToTransaction,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, ContentType, ContentDeleted, StructStore, ID, AbstractType, Transaction // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+import * as binary from 'lib0/binary'
+
+/**
+ * @todo This should return several items
+ *
+ * @param {StructStore} store
+ * @param {ID} id
+ * @return {{item:Item, diff:number}}
+ */
+export const followRedone = (store, id) => {
+  /**
+   * @type {ID|null}
+   */
+  let nextID = id
+  let diff = 0
+  let item
+  do {
+    if (diff > 0) {
+      nextID = createID(nextID.client, nextID.clock + diff)
+    }
+    item = getItem(store, nextID)
+    diff = nextID.clock - item.id.clock
+    nextID = item.redone
+  } while (nextID !== null && item instanceof Item)
+  return {
+    item, diff
+  }
+}
+
+/**
+ * Make sure that neither item nor any of its parents is ever deleted.
+ *
+ * This property does not persist when storing it into a database or when
+ * sending it to other peers
+ *
+ * @param {Item|null} item
+ * @param {boolean} keep
+ */
+export const keepItem = (item, keep) => {
+  while (item !== null && item.keep !== keep) {
+    item.keep = keep
+    item = /** @type {AbstractType<any>} */ (item.parent)._item
+  }
+}
+
+/**
+ * Split leftItem into two items
+ * @param {Transaction} transaction
+ * @param {Item} leftItem
+ * @param {number} diff
+ * @return {Item}
+ *
+ * @function
+ * @private
+ */
+export const splitItem = (transaction, leftItem, diff) => {
+  // create rightItem
+  const { client, clock } = leftItem.id
+  const rightItem = new Item(
+    createID(client, clock + diff),
+    leftItem,
+    createID(client, clock + diff - 1),
+    leftItem.right,
+    leftItem.rightOrigin,
+    leftItem.parent,
+    leftItem.parentSub,
+    leftItem.content.splice(diff)
+  )
+  if (leftItem.deleted) {
+    rightItem.markDeleted()
+  }
+  if (leftItem.keep) {
+    rightItem.keep = true
+  }
+  if (leftItem.redone !== null) {
+    rightItem.redone = createID(leftItem.redone.client, leftItem.redone.clock + diff)
+  }
+  // update left (do not set leftItem.rightOrigin as it will lead to problems when syncing)
+  leftItem.right = rightItem
+  // update right
+  if (rightItem.right !== null) {
+    rightItem.right.left = rightItem
+  }
+  // right is more specific.
+  transaction._mergeStructs.push(rightItem)
+  // update parent._map
+  if (rightItem.parentSub !== null && rightItem.right === null) {
+    /** @type {AbstractType<any>} */ (rightItem.parent)._map.set(rightItem.parentSub, rightItem)
+  }
+  leftItem.length = diff
+  return rightItem
+}
+
+/**
+ * Redoes the effect of this operation.
+ *
+ * @param {Transaction} transaction The Yjs instance.
+ * @param {Item} item
+ * @param {Set<Item>} redoitems
+ * @param {Array<Item>} itemsToDelete
+ *
+ * @return {Item|null}
+ *
+ * @private
+ */
+export const redoItem = (transaction, item, redoitems, itemsToDelete) => {
+  const doc = transaction.doc
+  const store = doc.store
+  const ownClientID = doc.clientID
+  const redone = item.redone
+  if (redone !== null) {
+    return getItemCleanStart(transaction, redone)
+  }
+  let parentItem = /** @type {AbstractType<any>} */ (item.parent)._item
+  /**
+   * @type {Item|null}
+   */
+  let left
+  /**
+   * @type {Item|null}
+   */
+  let right
+  if (item.parentSub === null) {
+    // Is an array item. Insert at the old position
+    left = item.left
+    right = item
+  } else {
+    // Is a map item. Insert as current value
+    left = item
+    while (left.right !== null) {
+      left = left.right
+      if (left.id.client !== ownClientID) {
+        // It is not possible to redo this item because it conflicts with a
+        // change from another client
+        return null
+      }
+    }
+    if (left.right !== null) {
+      left = /** @type {Item} */ (/** @type {AbstractType<any>} */ (item.parent)._map.get(item.parentSub))
+    }
+    right = null
+  }
+  // make sure that parent is redone
+  if (parentItem !== null && parentItem.deleted === true && parentItem.redone === null) {
+    // try to undo parent if it will be undone anyway
+    if (!redoitems.has(parentItem) || redoItem(transaction, parentItem, redoitems, itemsToDelete) === null) {
+      return null
+    }
+  }
+  if (parentItem !== null && parentItem.redone !== null) {
+    while (parentItem.redone !== null) {
+      parentItem = getItemCleanStart(transaction, parentItem.redone)
+    }
+    // find next cloned_redo items
+    while (left !== null) {
+      /**
+       * @type {Item|null}
+       */
+      let leftTrace = left
+      // trace redone until parent matches
+      while (leftTrace !== null && /** @type {AbstractType<any>} */ (leftTrace.parent)._item !== parentItem) {
+        leftTrace = leftTrace.redone === null ? null : getItemCleanStart(transaction, leftTrace.redone)
+      }
+      if (leftTrace !== null && /** @type {AbstractType<any>} */ (leftTrace.parent)._item === parentItem) {
+        left = leftTrace
+        break
+      }
+      left = left.left
+    }
+    while (right !== null) {
+      /**
+       * @type {Item|null}
+       */
+      let rightTrace = right
+      // trace redone until parent matches
+      while (rightTrace !== null && /** @type {AbstractType<any>} */ (rightTrace.parent)._item !== parentItem) {
+        rightTrace = rightTrace.redone === null ? null : getItemCleanStart(transaction, rightTrace.redone)
+      }
+      if (rightTrace !== null && /** @type {AbstractType<any>} */ (rightTrace.parent)._item === parentItem) {
+        right = rightTrace
+        break
+      }
+      right = right.right
+    }
+    // Iterate right while right is in itemsToDelete
+    // If it is intended to delete right while item is redone, we can expect that item should replace right.
+    while (left !== null && left.right !== null && left.right !== right && itemsToDelete.findIndex(d => d === /** @type {Item} */ (left).right) >= 0) {
+      left = left.right
+    }
+  }
+  const nextClock = getState(store, ownClientID)
+  const nextId = createID(ownClientID, nextClock)
+  const redoneItem = new Item(
+    nextId,
+    left, left && left.lastId,
+    right, right && right.id,
+    parentItem === null ? item.parent : /** @type {ContentType} */ (parentItem.content).type,
+    item.parentSub,
+    item.content.copy()
+  )
+  item.redone = nextId
+  keepItem(redoneItem, true)
+  redoneItem.integrate(transaction, 0)
+  return redoneItem
+}
+
+/**
+ * Abstract class that represents any content.
+ */
+export class Item extends AbstractStruct {
+  /**
+   * @param {ID} id
+   * @param {Item | null} left
+   * @param {ID | null} origin
+   * @param {Item | null} right
+   * @param {ID | null} rightOrigin
+   * @param {AbstractType<any>|ID|null} parent Is a type if integrated, is null if it is possible to copy parent from left or right, is ID before integration to search for it.
+   * @param {string | null} parentSub
+   * @param {AbstractContent} content
+   */
+  constructor (id, left, origin, right, rightOrigin, parent, parentSub, content) {
+    super(id, content.getLength())
+    /**
+     * The item that was originally to the left of this item.
+     * @type {ID | null}
+     */
+    this.origin = origin
+    /**
+     * The item that is currently to the left of this item.
+     * @type {Item | null}
+     */
+    this.left = left
+    /**
+     * The item that is currently to the right of this item.
+     * @type {Item | null}
+     */
+    this.right = right
+    /**
+     * The item that was originally to the right of this item.
+     * @type {ID | null}
+     */
+    this.rightOrigin = rightOrigin
+    /**
+     * @type {AbstractType<any>|ID|null}
+     */
+    this.parent = parent
+    /**
+     * If the parent refers to this item with some kind of key (e.g. YMap, the
+     * key is specified here. The key is then used to refer to the list in which
+     * to insert this item. If `parentSub = null` type._start is the list in
+     * which to insert to. Otherwise it is `parent._map`.
+     * @type {String | null}
+     */
+    this.parentSub = parentSub
+    /**
+     * If this type's effect is reundone this type refers to the type that undid
+     * this operation.
+     * @type {ID | null}
+     */
+    this.redone = null
+    /**
+     * @type {AbstractContent}
+     */
+    this.content = content
+    /**
+     * bit1: keep
+     * bit2: countable
+     * bit3: deleted
+     * bit4: mark - mark node as fast-search-marker
+     * @type {number} byte
+     */
+    this.info = this.content.isCountable() ? binary.BIT2 : 0
+  }
+
+  /**
+   * This is used to mark the item as an indexed fast-search marker
+   *
+   * @type {boolean}
+   */
+  set marker (isMarked) {
+    if (((this.info & binary.BIT4) > 0) !== isMarked) {
+      this.info ^= binary.BIT4
+    }
+  }
+
+  get marker () {
+    return (this.info & binary.BIT4) > 0
+  }
+
+  /**
+   * If true, do not garbage collect this Item.
+   */
+  get keep () {
+    return (this.info & binary.BIT1) > 0
+  }
+
+  set keep (doKeep) {
+    if (this.keep !== doKeep) {
+      this.info ^= binary.BIT1
+    }
+  }
+
+  get countable () {
+    return (this.info & binary.BIT2) > 0
+  }
+
+  /**
+   * Whether this item was deleted or not.
+   * @type {Boolean}
+   */
+  get deleted () {
+    return (this.info & binary.BIT3) > 0
+  }
+
+  set deleted (doDelete) {
+    if (this.deleted !== doDelete) {
+      this.info ^= binary.BIT3
+    }
+  }
+
+  markDeleted () {
+    this.info |= binary.BIT3
+  }
+
+  /**
+   * Return the creator clientID of the missing op or define missing items and return null.
+   *
+   * @param {Transaction} transaction
+   * @param {StructStore} store
+   * @return {null | number}
+   */
+  getMissing (transaction, store) {
+    if (this.origin && this.origin.client !== this.id.client && this.origin.clock >= getState(store, this.origin.client)) {
+      return this.origin.client
+    }
+    if (this.rightOrigin && this.rightOrigin.client !== this.id.client && this.rightOrigin.clock >= getState(store, this.rightOrigin.client)) {
+      return this.rightOrigin.client
+    }
+    if (this.parent && this.parent.constructor === ID && this.id.client !== this.parent.client && this.parent.clock >= getState(store, this.parent.client)) {
+      return this.parent.client
+    }
+
+    // We have all missing ids, now find the items
+
+    if (this.origin) {
+      this.left = getItemCleanEnd(transaction, store, this.origin)
+      this.origin = this.left.lastId
+    }
+    if (this.rightOrigin) {
+      this.right = getItemCleanStart(transaction, this.rightOrigin)
+      this.rightOrigin = this.right.id
+    }
+    if ((this.left && this.left.constructor === GC) || (this.right && this.right.constructor === GC)) {
+      this.parent = null
+    }
+    // only set parent if this shouldn't be garbage collected
+    if (!this.parent) {
+      if (this.left && this.left.constructor === Item) {
+        this.parent = this.left.parent
+        this.parentSub = this.left.parentSub
+      }
+      if (this.right && this.right.constructor === Item) {
+        this.parent = this.right.parent
+        this.parentSub = this.right.parentSub
+      }
+    } else if (this.parent.constructor === ID) {
+      const parentItem = getItem(store, this.parent)
+      if (parentItem.constructor === GC) {
+        this.parent = null
+      } else {
+        this.parent = /** @type {ContentType} */ (parentItem.content).type
+      }
+    }
+    return null
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {number} offset
+   */
+  integrate (transaction, offset) {
+    if (offset > 0) {
+      this.id.clock += offset
+      this.left = getItemCleanEnd(transaction, transaction.doc.store, createID(this.id.client, this.id.clock - 1))
+      this.origin = this.left.lastId
+      this.content = this.content.splice(offset)
+      this.length -= offset
+    }
+
+    if (this.parent) {
+      if ((!this.left && (!this.right || this.right.left !== null)) || (this.left && this.left.right !== this.right)) {
+        /**
+         * @type {Item|null}
+         */
+        let left = this.left
+
+        /**
+         * @type {Item|null}
+         */
+        let o
+        // set o to the first conflicting item
+        if (left !== null) {
+          o = left.right
+        } else if (this.parentSub !== null) {
+          o = /** @type {AbstractType<any>} */ (this.parent)._map.get(this.parentSub) || null
+          while (o !== null && o.left !== null) {
+            o = o.left
+          }
+        } else {
+          o = /** @type {AbstractType<any>} */ (this.parent)._start
+        }
+        // TODO: use something like DeleteSet here (a tree implementation would be best)
+        // @todo use global set definitions
+        /**
+         * @type {Set<Item>}
+         */
+        const conflictingItems = new Set()
+        /**
+         * @type {Set<Item>}
+         */
+        const itemsBeforeOrigin = new Set()
+        // Let c in conflictingItems, b in itemsBeforeOrigin
+        // ***{origin}bbbb{this}{c,b}{c,b}{o}***
+        // Note that conflictingItems is a subset of itemsBeforeOrigin
+        while (o !== null && o !== this.right) {
+          itemsBeforeOrigin.add(o)
+          conflictingItems.add(o)
+          if (compareIDs(this.origin, o.origin)) {
+            // case 1
+            if (o.id.client < this.id.client) {
+              left = o
+              conflictingItems.clear()
+            } else if (compareIDs(this.rightOrigin, o.rightOrigin)) {
+              // this and o are conflicting and point to the same integration points. The id decides which item comes first.
+              // Since this is to the left of o, we can break here
+              break
+            } // else, o might be integrated before an item that this conflicts with. If so, we will find it in the next iterations
+          } else if (o.origin !== null && itemsBeforeOrigin.has(getItem(transaction.doc.store, o.origin))) { // use getItem instead of getItemCleanEnd because we don't want / need to split items.
+            // case 2
+            if (!conflictingItems.has(getItem(transaction.doc.store, o.origin))) {
+              left = o
+              conflictingItems.clear()
+            }
+          } else {
+            break
+          }
+          o = o.right
+        }
+        this.left = left
+      }
+      // reconnect left/right + update parent map/start if necessary
+      if (this.left !== null) {
+        const right = this.left.right
+        this.right = right
+        this.left.right = this
+      } else {
+        let r
+        if (this.parentSub !== null) {
+          r = /** @type {AbstractType<any>} */ (this.parent)._map.get(this.parentSub) || null
+          while (r !== null && r.left !== null) {
+            r = r.left
+          }
+        } else {
+          r = /** @type {AbstractType<any>} */ (this.parent)._start
+          ;/** @type {AbstractType<any>} */ (this.parent)._start = this
+        }
+        this.right = r
+      }
+      if (this.right !== null) {
+        this.right.left = this
+      } else if (this.parentSub !== null) {
+        // set as current parent value if right === null and this is parentSub
+        /** @type {AbstractType<any>} */ (this.parent)._map.set(this.parentSub, this)
+        if (this.left !== null) {
+          // this is the current attribute value of parent. delete right
+          this.left.delete(transaction)
+        }
+      }
+      // adjust length of parent
+      if (this.parentSub === null && this.countable && !this.deleted) {
+        /** @type {AbstractType<any>} */ (this.parent)._length += this.length
+      }
+      addStruct(transaction.doc.store, this)
+      this.content.integrate(transaction, this)
+      // add parent to transaction.changed
+      addChangedTypeToTransaction(transaction, /** @type {AbstractType<any>} */ (this.parent), this.parentSub)
+      if ((/** @type {AbstractType<any>} */ (this.parent)._item !== null && /** @type {AbstractType<any>} */ (this.parent)._item.deleted) || (this.parentSub !== null && this.right !== null)) {
+        // delete if parent is deleted or if this is not the current attribute value of parent
+        this.delete(transaction)
+      }
+    } else {
+      // parent is not defined. Integrate GC struct instead
+      new GC(this.id, this.length).integrate(transaction, 0)
+    }
+  }
+
+  /**
+   * Returns the next non-deleted item
+   */
+  get next () {
+    let n = this.right
+    while (n !== null && n.deleted) {
+      n = n.right
+    }
+    return n
+  }
+
+  /**
+   * Returns the previous non-deleted item
+   */
+  get prev () {
+    let n = this.left
+    while (n !== null && n.deleted) {
+      n = n.left
+    }
+    return n
+  }
+
+  /**
+   * Computes the last content address of this Item.
+   */
+  get lastId () {
+    // allocating ids is pretty costly because of the amount of ids created, so we try to reuse whenever possible
+    return this.length === 1 ? this.id : createID(this.id.client, this.id.clock + this.length - 1)
+  }
+
+  /**
+   * Try to merge two items
+   *
+   * @param {Item} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    if (
+      this.constructor === right.constructor &&
+      compareIDs(right.origin, this.lastId) &&
+      this.right === right &&
+      compareIDs(this.rightOrigin, right.rightOrigin) &&
+      this.id.client === right.id.client &&
+      this.id.clock + this.length === right.id.clock &&
+      this.deleted === right.deleted &&
+      this.redone === null &&
+      right.redone === null &&
+      this.content.constructor === right.content.constructor &&
+      this.content.mergeWith(right.content)
+    ) {
+      const searchMarker = /** @type {AbstractType<any>} */ (this.parent)._searchMarker
+      if (searchMarker) {
+        searchMarker.forEach(marker => {
+          if (marker.p === right) {
+            // right is going to be "forgotten" so we need to update the marker
+            marker.p = this
+            // adjust marker index
+            if (!this.deleted && this.countable) {
+              marker.index -= this.length
+            }
+          }
+        })
+      }
+      if (right.keep) {
+        this.keep = true
+      }
+      this.right = right.right
+      if (this.right !== null) {
+        this.right.left = this
+      }
+      this.length += right.length
+      return true
+    }
+    return false
+  }
+
+  /**
+   * Mark this Item as deleted.
+   *
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {
+    if (!this.deleted) {
+      const parent = /** @type {AbstractType<any>} */ (this.parent)
+      // adjust the length of parent
+      if (this.countable && this.parentSub === null) {
+        parent._length -= this.length
+      }
+      this.markDeleted()
+      addToDeleteSet(transaction.deleteSet, this.id.client, this.id.clock, this.length)
+      addChangedTypeToTransaction(transaction, parent, this.parentSub)
+      this.content.delete(transaction)
+    }
+  }
+
+  /**
+   * @param {StructStore} store
+   * @param {boolean} parentGCd
+   */
+  gc (store, parentGCd) {
+    if (!this.deleted) {
+      throw error.unexpectedCase()
+    }
+    this.content.gc(store)
+    if (parentGCd) {
+      replaceStruct(store, this, new GC(this.id, this.length))
+    } else {
+      this.content = new ContentDeleted(this.length)
+    }
+  }
+
+  /**
+   * Transform the properties of this type to binary and write it to an
+   * BinaryEncoder.
+   *
+   * This is called when this Item is sent to a remote peer.
+   *
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder The encoder to write data to.
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    const origin = offset > 0 ? createID(this.id.client, this.id.clock + offset - 1) : this.origin
+    const rightOrigin = this.rightOrigin
+    const parentSub = this.parentSub
+    const info = (this.content.getRef() & binary.BITS5) |
+      (origin === null ? 0 : binary.BIT8) | // origin is defined
+      (rightOrigin === null ? 0 : binary.BIT7) | // right origin is defined
+      (parentSub === null ? 0 : binary.BIT6) // parentSub is non-null
+    encoder.writeInfo(info)
+    if (origin !== null) {
+      encoder.writeLeftID(origin)
+    }
+    if (rightOrigin !== null) {
+      encoder.writeRightID(rightOrigin)
+    }
+    if (origin === null && rightOrigin === null) {
+      const parent = /** @type {AbstractType<any>} */ (this.parent)
+      if (parent._item !== undefined) {
+        const parentItem = parent._item
+        if (parentItem === null) {
+          // parent type on y._map
+          // find the correct key
+          const ykey = findRootTypeKey(parent)
+          encoder.writeParentInfo(true) // write parentYKey
+          encoder.writeString(ykey)
+        } else {
+          encoder.writeParentInfo(false) // write parent id
+          encoder.writeLeftID(parentItem.id)
+        }
+      } else if (parent.constructor === String) { // this edge case was added by differential updates
+        encoder.writeParentInfo(true) // write parentYKey
+        encoder.writeString(parent)
+      } else if (parent.constructor === ID) {
+        encoder.writeParentInfo(false) // write parent id
+        encoder.writeLeftID(parent)
+      } else {
+        error.unexpectedCase()
+      }
+      if (parentSub !== null) {
+        encoder.writeString(parentSub)
+      }
+    }
+    this.content.write(encoder, offset)
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @param {number} info
+ */
+export const readItemContent = (decoder, info) => contentRefs[info & binary.BITS5](decoder)
+
+/**
+ * A lookup map for reading Item content.
+ *
+ * @type {Array<function(UpdateDecoderV1 | UpdateDecoderV2):AbstractContent>}
+ */
+export const contentRefs = [
+  () => { error.unexpectedCase() }, // GC is not ItemContent
+  readContentDeleted, // 1
+  readContentJSON, // 2
+  readContentBinary, // 3
+  readContentString, // 4
+  readContentEmbed, // 5
+  readContentFormat, // 6
+  readContentType, // 7
+  readContentAny, // 8
+  readContentDoc, // 9
+  () => { error.unexpectedCase() } // 10 - Skip is not ItemContent
+]
+
+/**
+ * Do not implement this class!
+ */
+export class AbstractContent {
+  /**
+   * @return {number}
+   */
+  getLength () {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * Should return false if this Item is some kind of meta information
+   * (e.g. format information).
+   *
+   * * Whether this Item should be addressable via `yarray.get(i)`
+   * * Whether this Item should be counted when computing yarray.length
+   *
+   * @return {boolean}
+   */
+  isCountable () {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @return {AbstractContent}
+   */
+  copy () {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {number} offset
+   * @return {AbstractContent}
+   */
+  splice (offset) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {AbstractContent} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {Transaction} transaction
+   */
+  delete (transaction) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    throw error.methodUnimplemented()
+  }
+}

src/structs/Skip.js

@@ -0,0 +1,60 @@
+
+import {
+  AbstractStruct,
+  UpdateEncoderV1, UpdateEncoderV2, StructStore, Transaction, ID // eslint-disable-line
+} from '../internals.js'
+import * as error from 'lib0/error'
+import * as encoding from 'lib0/encoding'
+
+export const structSkipRefNumber = 10
+
+/**
+ * @private
+ */
+export class Skip extends AbstractStruct {
+  get deleted () {
+    return true
+  }
+
+  delete () {}
+
+  /**
+   * @param {Skip} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    if (this.constructor !== right.constructor) {
+      return false
+    }
+    this.length += right.length
+    return true
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {number} offset
+   */
+  integrate (transaction, offset) {
+    // skip structs cannot be integrated
+    error.unexpectedCase()
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeInfo(structSkipRefNumber)
+    // write as VarUint because Skips can't make use of predictable length-encoding
+    encoding.writeVarUint(encoder.restEncoder, this.length - offset)
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {StructStore} store
+   * @return {null | number}
+   */
+  getMissing (transaction, store) {
+    return null
+  }
+}

src/types/AbstractType.js

@@ -0,0 +1,912 @@
+
+import {
+  removeEventHandlerListener,
+  callEventHandlerListeners,
+  addEventHandlerListener,
+  createEventHandler,
+  getState,
+  isVisible,
+  ContentType,
+  createID,
+  ContentAny,
+  ContentBinary,
+  getItemCleanStart,
+  ContentDoc, YText, YArray, UpdateEncoderV1, UpdateEncoderV2, Doc, Snapshot, Transaction, EventHandler, YEvent, Item, // eslint-disable-line
+} from '../internals.js'
+
+import * as map from 'lib0/map'
+import * as iterator from 'lib0/iterator'
+import * as error from 'lib0/error'
+import * as math from 'lib0/math'
+
+const maxSearchMarker = 80
+
+/**
+ * A unique timestamp that identifies each marker.
+ *
+ * Time is relative,.. this is more like an ever-increasing clock.
+ *
+ * @type {number}
+ */
+let globalSearchMarkerTimestamp = 0
+
+export class ArraySearchMarker {
+  /**
+   * @param {Item} p
+   * @param {number} index
+   */
+  constructor (p, index) {
+    p.marker = true
+    this.p = p
+    this.index = index
+    this.timestamp = globalSearchMarkerTimestamp++
+  }
+}
+
+/**
+ * @param {ArraySearchMarker} marker
+ */
+const refreshMarkerTimestamp = marker => { marker.timestamp = globalSearchMarkerTimestamp++ }
+
+/**
+ * This is rather complex so this function is the only thing that should overwrite a marker
+ *
+ * @param {ArraySearchMarker} marker
+ * @param {Item} p
+ * @param {number} index
+ */
+const overwriteMarker = (marker, p, index) => {
+  marker.p.marker = false
+  marker.p = p
+  p.marker = true
+  marker.index = index
+  marker.timestamp = globalSearchMarkerTimestamp++
+}
+
+/**
+ * @param {Array<ArraySearchMarker>} searchMarker
+ * @param {Item} p
+ * @param {number} index
+ */
+const markPosition = (searchMarker, p, index) => {
+  if (searchMarker.length >= maxSearchMarker) {
+    // override oldest marker (we don't want to create more objects)
+    const marker = searchMarker.reduce((a, b) => a.timestamp < b.timestamp ? a : b)
+    overwriteMarker(marker, p, index)
+    return marker
+  } else {
+    // create new marker
+    const pm = new ArraySearchMarker(p, index)
+    searchMarker.push(pm)
+    return pm
+  }
+}
+
+/**
+ * Search marker help us to find positions in the associative array faster.
+ *
+ * They speed up the process of finding a position without much bookkeeping.
+ *
+ * A maximum of `maxSearchMarker` objects are created.
+ *
+ * This function always returns a refreshed marker (updated timestamp)
+ *
+ * @param {AbstractType<any>} yarray
+ * @param {number} index
+ */
+export const findMarker = (yarray, index) => {
+  if (yarray._start === null || index === 0 || yarray._searchMarker === null) {
+    return null
+  }
+  const marker = yarray._searchMarker.length === 0 ? null : yarray._searchMarker.reduce((a, b) => math.abs(index - a.index) < math.abs(index - b.index) ? a : b)
+  let p = yarray._start
+  let pindex = 0
+  if (marker !== null) {
+    p = marker.p
+    pindex = marker.index
+    refreshMarkerTimestamp(marker) // we used it, we might need to use it again
+  }
+  // iterate to right if possible
+  while (p.right !== null && pindex < index) {
+    if (!p.deleted && p.countable) {
+      if (index < pindex + p.length) {
+        break
+      }
+      pindex += p.length
+    }
+    p = p.right
+  }
+  // iterate to left if necessary (might be that pindex > index)
+  while (p.left !== null && pindex > index) {
+    p = p.left
+    if (!p.deleted && p.countable) {
+      pindex -= p.length
+    }
+  }
+  // we want to make sure that p can't be merged with left, because that would screw up everything
+  // in that cas just return what we have (it is most likely the best marker anyway)
+  // iterate to left until p can't be merged with left
+  while (p.left !== null && p.left.id.client === p.id.client && p.left.id.clock + p.left.length === p.id.clock) {
+    p = p.left
+    if (!p.deleted && p.countable) {
+      pindex -= p.length
+    }
+  }
+
+  // @todo remove!
+  // assure position
+  // {
+  //   let start = yarray._start
+  //   let pos = 0
+  //   while (start !== p) {
+  //     if (!start.deleted && start.countable) {
+  //       pos += start.length
+  //     }
+  //     start = /** @type {Item} */ (start.right)
+  //   }
+  //   if (pos !== pindex) {
+  //     debugger
+  //     throw new Error('Gotcha position fail!')
+  //   }
+  // }
+  // if (marker) {
+  //   if (window.lengthes == null) {
+  //     window.lengthes = []
+  //     window.getLengthes = () => window.lengthes.sort((a, b) => a - b)
+  //   }
+  //   window.lengthes.push(marker.index - pindex)
+  //   console.log('distance', marker.index - pindex, 'len', p && p.parent.length)
+  // }
+  if (marker !== null && math.abs(marker.index - pindex) < /** @type {YText|YArray<any>} */ (p.parent).length / maxSearchMarker) {
+    // adjust existing marker
+    overwriteMarker(marker, p, pindex)
+    return marker
+  } else {
+    // create new marker
+    return markPosition(yarray._searchMarker, p, pindex)
+  }
+}
+
+/**
+ * Update markers when a change happened.
+ *
+ * This should be called before doing a deletion!
+ *
+ * @param {Array<ArraySearchMarker>} searchMarker
+ * @param {number} index
+ * @param {number} len If insertion, len is positive. If deletion, len is negative.
+ */
+export const updateMarkerChanges = (searchMarker, index, len) => {
+  for (let i = searchMarker.length - 1; i >= 0; i--) {
+    const m = searchMarker[i]
+    if (len > 0) {
+      /**
+       * @type {Item|null}
+       */
+      let p = m.p
+      p.marker = false
+      // Ideally we just want to do a simple position comparison, but this will only work if
+      // search markers don't point to deleted items for formats.
+      // Iterate marker to prev undeleted countable position so we know what to do when updating a position
+      while (p && (p.deleted || !p.countable)) {
+        p = p.left
+        if (p && !p.deleted && p.countable) {
+          // adjust position. the loop should break now
+          m.index -= p.length
+        }
+      }
+      if (p === null || p.marker === true) {
+        // remove search marker if updated position is null or if position is already marked
+        searchMarker.splice(i, 1)
+        continue
+      }
+      m.p = p
+      p.marker = true
+    }
+    if (index < m.index || (len > 0 && index === m.index)) { // a simple index <= m.index check would actually suffice
+      m.index = math.max(index, m.index + len)
+    }
+  }
+}
+
+/**
+ * Accumulate all (list) children of a type and return them as an Array.
+ *
+ * @param {AbstractType<any>} t
+ * @return {Array<Item>}
+ */
+export const getTypeChildren = t => {
+  let s = t._start
+  const arr = []
+  while (s) {
+    arr.push(s)
+    s = s.right
+  }
+  return arr
+}
+
+/**
+ * Call event listeners with an event. This will also add an event to all
+ * parents (for `.observeDeep` handlers).
+ *
+ * @template EventType
+ * @param {AbstractType<EventType>} type
+ * @param {Transaction} transaction
+ * @param {EventType} event
+ */
+export const callTypeObservers = (type, transaction, event) => {
+  const changedType = type
+  const changedParentTypes = transaction.changedParentTypes
+  while (true) {
+    // @ts-ignore
+    map.setIfUndefined(changedParentTypes, type, () => []).push(event)
+    if (type._item === null) {
+      break
+    }
+    type = /** @type {AbstractType<any>} */ (type._item.parent)
+  }
+  callEventHandlerListeners(changedType._eH, event, transaction)
+}
+
+/**
+ * @template EventType
+ * Abstract Yjs Type class
+ */
+export class AbstractType {
+  constructor () {
+    /**
+     * @type {Item|null}
+     */
+    this._item = null
+    /**
+     * @type {Map<string,Item>}
+     */
+    this._map = new Map()
+    /**
+     * @type {Item|null}
+     */
+    this._start = null
+    /**
+     * @type {Doc|null}
+     */
+    this.doc = null
+    this._length = 0
+    /**
+     * Event handlers
+     * @type {EventHandler<EventType,Transaction>}
+     */
+    this._eH = createEventHandler()
+    /**
+     * Deep event handlers
+     * @type {EventHandler<Array<YEvent>,Transaction>}
+     */
+    this._dEH = createEventHandler()
+    /**
+     * @type {null | Array<ArraySearchMarker>}
+     */
+    this._searchMarker = null
+  }
+
+  /**
+   * @return {AbstractType<any>|null}
+   */
+  get parent () {
+    return this._item ? /** @type {AbstractType<any>} */ (this._item.parent) : null
+  }
+
+  /**
+   * Integrate this type into the Yjs instance.
+   *
+   * * Save this struct in the os
+   * * This type is sent to other client
+   * * Observer functions are fired
+   *
+   * @param {Doc} y The Yjs instance
+   * @param {Item|null} item
+   */
+  _integrate (y, item) {
+    this.doc = y
+    this._item = item
+  }
+
+  /**
+   * @return {AbstractType<EventType>}
+   */
+  _copy () {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @return {AbstractType<EventType>}
+   */
+  clone () {
+    throw error.methodUnimplemented()
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   */
+  _write (encoder) { }
+
+  /**
+   * The first non-deleted item
+   */
+  get _first () {
+    let n = this._start
+    while (n !== null && n.deleted) {
+      n = n.right
+    }
+    return n
+  }
+
+  /**
+   * Creates YEvent and calls all type observers.
+   * Must be implemented by each type.
+   *
+   * @param {Transaction} transaction
+   * @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
+   */
+  _callObserver (transaction, parentSubs) {
+    if (!transaction.local && this._searchMarker) {
+      this._searchMarker.length = 0
+    }
+  }
+
+  /**
+   * Observe all events that are created on this type.
+   *
+   * @param {function(EventType, Transaction):void} f Observer function
+   */
+  observe (f) {
+    addEventHandlerListener(this._eH, f)
+  }
+
+  /**
+   * Observe all events that are created by this type and its children.
+   *
+   * @param {function(Array<YEvent>,Transaction):void} f Observer function
+   */
+  observeDeep (f) {
+    addEventHandlerListener(this._dEH, f)
+  }
+
+  /**
+   * Unregister an observer function.
+   *
+   * @param {function(EventType,Transaction):void} f Observer function
+   */
+  unobserve (f) {
+    removeEventHandlerListener(this._eH, f)
+  }
+
+  /**
+   * Unregister an observer function.
+   *
+   * @param {function(Array<YEvent>,Transaction):void} f Observer function
+   */
+  unobserveDeep (f) {
+    removeEventHandlerListener(this._dEH, f)
+  }
+
+  /**
+   * @abstract
+   * @return {any}
+   */
+  toJSON () {}
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {number} start
+ * @param {number} end
+ * @return {Array<any>}
+ *
+ * @private
+ * @function
+ */
+export const typeListSlice = (type, start, end) => {
+  if (start < 0) {
+    start = type._length + start
+  }
+  if (end < 0) {
+    end = type._length + end
+  }
+  let len = end - start
+  const cs = []
+  let n = type._start
+  while (n !== null && len > 0) {
+    if (n.countable && !n.deleted) {
+      const c = n.content.getContent()
+      if (c.length <= start) {
+        start -= c.length
+      } else {
+        for (let i = start; i < c.length && len > 0; i++) {
+          cs.push(c[i])
+          len--
+        }
+        start = 0
+      }
+    }
+    n = n.right
+  }
+  return cs
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @return {Array<any>}
+ *
+ * @private
+ * @function
+ */
+export const typeListToArray = type => {
+  const cs = []
+  let n = type._start
+  while (n !== null) {
+    if (n.countable && !n.deleted) {
+      const c = n.content.getContent()
+      for (let i = 0; i < c.length; i++) {
+        cs.push(c[i])
+      }
+    }
+    n = n.right
+  }
+  return cs
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {Snapshot} snapshot
+ * @return {Array<any>}
+ *
+ * @private
+ * @function
+ */
+export const typeListToArraySnapshot = (type, snapshot) => {
+  const cs = []
+  let n = type._start
+  while (n !== null) {
+    if (n.countable && isVisible(n, snapshot)) {
+      const c = n.content.getContent()
+      for (let i = 0; i < c.length; i++) {
+        cs.push(c[i])
+      }
+    }
+    n = n.right
+  }
+  return cs
+}
+
+/**
+ * Executes a provided function on once on overy element of this YArray.
+ *
+ * @param {AbstractType<any>} type
+ * @param {function(any,number,any):void} f A function to execute on every element of this YArray.
+ *
+ * @private
+ * @function
+ */
+export const typeListForEach = (type, f) => {
+  let index = 0
+  let n = type._start
+  while (n !== null) {
+    if (n.countable && !n.deleted) {
+      const c = n.content.getContent()
+      for (let i = 0; i < c.length; i++) {
+        f(c[i], index++, type)
+      }
+    }
+    n = n.right
+  }
+}
+
+/**
+ * @template C,R
+ * @param {AbstractType<any>} type
+ * @param {function(C,number,AbstractType<any>):R} f
+ * @return {Array<R>}
+ *
+ * @private
+ * @function
+ */
+export const typeListMap = (type, f) => {
+  /**
+   * @type {Array<any>}
+   */
+  const result = []
+  typeListForEach(type, (c, i) => {
+    result.push(f(c, i, type))
+  })
+  return result
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @return {IterableIterator<any>}
+ *
+ * @private
+ * @function
+ */
+export const typeListCreateIterator = type => {
+  let n = type._start
+  /**
+   * @type {Array<any>|null}
+   */
+  let currentContent = null
+  let currentContentIndex = 0
+  return {
+    [Symbol.iterator] () {
+      return this
+    },
+    next: () => {
+      // find some content
+      if (currentContent === null) {
+        while (n !== null && n.deleted) {
+          n = n.right
+        }
+        // check if we reached the end, no need to check currentContent, because it does not exist
+        if (n === null) {
+          return {
+            done: true,
+            value: undefined
+          }
+        }
+        // we found n, so we can set currentContent
+        currentContent = n.content.getContent()
+        currentContentIndex = 0
+        n = n.right // we used the content of n, now iterate to next
+      }
+      const value = currentContent[currentContentIndex++]
+      // check if we need to empty currentContent
+      if (currentContent.length <= currentContentIndex) {
+        currentContent = null
+      }
+      return {
+        done: false,
+        value
+      }
+    }
+  }
+}
+
+/**
+ * Executes a provided function on once on overy element of this YArray.
+ * Operates on a snapshotted state of the document.
+ *
+ * @param {AbstractType<any>} type
+ * @param {function(any,number,AbstractType<any>):void} f A function to execute on every element of this YArray.
+ * @param {Snapshot} snapshot
+ *
+ * @private
+ * @function
+ */
+export const typeListForEachSnapshot = (type, f, snapshot) => {
+  let index = 0
+  let n = type._start
+  while (n !== null) {
+    if (n.countable && isVisible(n, snapshot)) {
+      const c = n.content.getContent()
+      for (let i = 0; i < c.length; i++) {
+        f(c[i], index++, type)
+      }
+    }
+    n = n.right
+  }
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {number} index
+ * @return {any}
+ *
+ * @private
+ * @function
+ */
+export const typeListGet = (type, index) => {
+  const marker = findMarker(type, index)
+  let n = type._start
+  if (marker !== null) {
+    n = marker.p
+    index -= marker.index
+  }
+  for (; n !== null; n = n.right) {
+    if (!n.deleted && n.countable) {
+      if (index < n.length) {
+        return n.content.getContent()[index]
+      }
+      index -= n.length
+    }
+  }
+}
+
+/**
+ * @param {Transaction} transaction
+ * @param {AbstractType<any>} parent
+ * @param {Item?} referenceItem
+ * @param {Array<Object<string,any>|Array<any>|boolean|number|null|string|Uint8Array>} content
+ *
+ * @private
+ * @function
+ */
+export const typeListInsertGenericsAfter = (transaction, parent, referenceItem, content) => {
+  let left = referenceItem
+  const doc = transaction.doc
+  const ownClientId = doc.clientID
+  const store = doc.store
+  const right = referenceItem === null ? parent._start : referenceItem.right
+  /**
+   * @type {Array<Object|Array<any>|number|null>}
+   */
+  let jsonContent = []
+  const packJsonContent = () => {
+    if (jsonContent.length > 0) {
+      left = new Item(createID(ownClientId, getState(store, ownClientId)), left, left && left.lastId, right, right && right.id, parent, null, new ContentAny(jsonContent))
+      left.integrate(transaction, 0)
+      jsonContent = []
+    }
+  }
+  content.forEach(c => {
+    if (c === null) {
+      jsonContent.push(c)
+    } else {
+      switch (c.constructor) {
+        case Number:
+        case Object:
+        case Boolean:
+        case Array:
+        case String:
+          jsonContent.push(c)
+          break
+        default:
+          packJsonContent()
+          switch (c.constructor) {
+            case Uint8Array:
+            case ArrayBuffer:
+              left = new Item(createID(ownClientId, getState(store, ownClientId)), left, left && left.lastId, right, right && right.id, parent, null, new ContentBinary(new Uint8Array(/** @type {Uint8Array} */ (c))))
+              left.integrate(transaction, 0)
+              break
+            case Doc:
+              left = new Item(createID(ownClientId, getState(store, ownClientId)), left, left && left.lastId, right, right && right.id, parent, null, new ContentDoc(/** @type {Doc} */ (c)))
+              left.integrate(transaction, 0)
+              break
+            default:
+              if (c instanceof AbstractType) {
+                left = new Item(createID(ownClientId, getState(store, ownClientId)), left, left && left.lastId, right, right && right.id, parent, null, new ContentType(c))
+                left.integrate(transaction, 0)
+              } else {
+                throw new Error('Unexpected content type in insert operation')
+              }
+          }
+      }
+    }
+  })
+  packJsonContent()
+}
+
+const lengthExceeded = error.create('Length exceeded!')
+
+/**
+ * @param {Transaction} transaction
+ * @param {AbstractType<any>} parent
+ * @param {number} index
+ * @param {Array<Object<string,any>|Array<any>|number|null|string|Uint8Array>} content
+ *
+ * @private
+ * @function
+ */
+export const typeListInsertGenerics = (transaction, parent, index, content) => {
+  if (index > parent._length) {
+    throw lengthExceeded
+  }
+  if (index === 0) {
+    if (parent._searchMarker) {
+      updateMarkerChanges(parent._searchMarker, index, content.length)
+    }
+    return typeListInsertGenericsAfter(transaction, parent, null, content)
+  }
+  const startIndex = index
+  const marker = findMarker(parent, index)
+  let n = parent._start
+  if (marker !== null) {
+    n = marker.p
+    index -= marker.index
+    // we need to iterate one to the left so that the algorithm works
+    if (index === 0) {
+      // @todo refactor this as it actually doesn't consider formats
+      n = n.prev // important! get the left undeleted item so that we can actually decrease index
+      index += (n && n.countable && !n.deleted) ? n.length : 0
+    }
+  }
+  for (; n !== null; n = n.right) {
+    if (!n.deleted && n.countable) {
+      if (index <= n.length) {
+        if (index < n.length) {
+          // insert in-between
+          getItemCleanStart(transaction, createID(n.id.client, n.id.clock + index))
+        }
+        break
+      }
+      index -= n.length
+    }
+  }
+  if (parent._searchMarker) {
+    updateMarkerChanges(parent._searchMarker, startIndex, content.length)
+  }
+  return typeListInsertGenericsAfter(transaction, parent, n, content)
+}
+
+/**
+ * @param {Transaction} transaction
+ * @param {AbstractType<any>} parent
+ * @param {number} index
+ * @param {number} length
+ *
+ * @private
+ * @function
+ */
+export const typeListDelete = (transaction, parent, index, length) => {
+  if (length === 0) { return }
+  const startIndex = index
+  const startLength = length
+  const marker = findMarker(parent, index)
+  let n = parent._start
+  if (marker !== null) {
+    n = marker.p
+    index -= marker.index
+  }
+  // compute the first item to be deleted
+  for (; n !== null && index > 0; n = n.right) {
+    if (!n.deleted && n.countable) {
+      if (index < n.length) {
+        getItemCleanStart(transaction, createID(n.id.client, n.id.clock + index))
+      }
+      index -= n.length
+    }
+  }
+  // delete all items until done
+  while (length > 0 && n !== null) {
+    if (!n.deleted) {
+      if (length < n.length) {
+        getItemCleanStart(transaction, createID(n.id.client, n.id.clock + length))
+      }
+      n.delete(transaction)
+      length -= n.length
+    }
+    n = n.right
+  }
+  if (length > 0) {
+    throw lengthExceeded
+  }
+  if (parent._searchMarker) {
+    updateMarkerChanges(parent._searchMarker, startIndex, -startLength + length /* in case we remove the above exception */)
+  }
+}
+
+/**
+ * @param {Transaction} transaction
+ * @param {AbstractType<any>} parent
+ * @param {string} key
+ *
+ * @private
+ * @function
+ */
+export const typeMapDelete = (transaction, parent, key) => {
+  const c = parent._map.get(key)
+  if (c !== undefined) {
+    c.delete(transaction)
+  }
+}
+
+/**
+ * @param {Transaction} transaction
+ * @param {AbstractType<any>} parent
+ * @param {string} key
+ * @param {Object|number|null|Array<any>|string|Uint8Array|AbstractType<any>} value
+ *
+ * @private
+ * @function
+ */
+export const typeMapSet = (transaction, parent, key, value) => {
+  const left = parent._map.get(key) || null
+  const doc = transaction.doc
+  const ownClientId = doc.clientID
+  let content
+  if (value == null) {
+    content = new ContentAny([value])
+  } else {
+    switch (value.constructor) {
+      case Number:
+      case Object:
+      case Boolean:
+      case Array:
+      case String:
+        content = new ContentAny([value])
+        break
+      case Uint8Array:
+        content = new ContentBinary(/** @type {Uint8Array} */ (value))
+        break
+      case Doc:
+        content = new ContentDoc(/** @type {Doc} */ (value))
+        break
+      default:
+        if (value instanceof AbstractType) {
+          content = new ContentType(value)
+        } else {
+          throw new Error('Unexpected content type')
+        }
+    }
+  }
+  new Item(createID(ownClientId, getState(doc.store, ownClientId)), left, left && left.lastId, null, null, parent, key, content).integrate(transaction, 0)
+}
+
+/**
+ * @param {AbstractType<any>} parent
+ * @param {string} key
+ * @return {Object<string,any>|number|null|Array<any>|string|Uint8Array|AbstractType<any>|undefined}
+ *
+ * @private
+ * @function
+ */
+export const typeMapGet = (parent, key) => {
+  const val = parent._map.get(key)
+  return val !== undefined && !val.deleted ? val.content.getContent()[val.length - 1] : undefined
+}
+
+/**
+ * @param {AbstractType<any>} parent
+ * @return {Object<string,Object<string,any>|number|null|Array<any>|string|Uint8Array|AbstractType<any>|undefined>}
+ *
+ * @private
+ * @function
+ */
+export const typeMapGetAll = (parent) => {
+  /**
+   * @type {Object<string,any>}
+   */
+  const res = {}
+  parent._map.forEach((value, key) => {
+    if (!value.deleted) {
+      res[key] = value.content.getContent()[value.length - 1]
+    }
+  })
+  return res
+}
+
+/**
+ * @param {AbstractType<any>} parent
+ * @param {string} key
+ * @return {boolean}
+ *
+ * @private
+ * @function
+ */
+export const typeMapHas = (parent, key) => {
+  const val = parent._map.get(key)
+  return val !== undefined && !val.deleted
+}
+
+/**
+ * @param {AbstractType<any>} parent
+ * @param {string} key
+ * @param {Snapshot} snapshot
+ * @return {Object<string,any>|number|null|Array<any>|string|Uint8Array|AbstractType<any>|undefined}
+ *
+ * @private
+ * @function
+ */
+export const typeMapGetSnapshot = (parent, key, snapshot) => {
+  let v = parent._map.get(key) || null
+  while (v !== null && (!snapshot.sv.has(v.id.client) || v.id.clock >= (snapshot.sv.get(v.id.client) || 0))) {
+    v = v.left
+  }
+  return v !== null && isVisible(v, snapshot) ? v.content.getContent()[v.length - 1] : undefined
+}
+
+/**
+ * @param {Map<string,Item>} map
+ * @return {IterableIterator<Array<any>>}
+ *
+ * @private
+ * @function
+ */
+export const createMapIterator = map => iterator.iteratorFilter(map.entries(), /** @param {any} entry */ entry => !entry[1].deleted)

src/types/YArray.js

@@ -0,0 +1,257 @@
+/**
+ * @module YArray
+ */
+
+import {
+  YEvent,
+  AbstractType,
+  typeListGet,
+  typeListToArray,
+  typeListForEach,
+  typeListCreateIterator,
+  typeListInsertGenerics,
+  typeListDelete,
+  typeListMap,
+  YArrayRefID,
+  callTypeObservers,
+  transact,
+  ArraySearchMarker, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
+} from '../internals.js'
+import { typeListSlice } from './AbstractType.js'
+
+/**
+ * Event that describes the changes on a YArray
+ * @template T
+ */
+export class YArrayEvent extends YEvent {
+  /**
+   * @param {YArray<T>} yarray The changed type
+   * @param {Transaction} transaction The transaction object
+   */
+  constructor (yarray, transaction) {
+    super(yarray, transaction)
+    this._transaction = transaction
+  }
+}
+
+/**
+ * A shared Array implementation.
+ * @template T
+ * @extends AbstractType<YArrayEvent<T>>
+ * @implements {Iterable<T>}
+ */
+export class YArray extends AbstractType {
+  constructor () {
+    super()
+    /**
+     * @type {Array<any>?}
+     * @private
+     */
+    this._prelimContent = []
+    /**
+     * @type {Array<ArraySearchMarker>}
+     */
+    this._searchMarker = []
+  }
+
+  /**
+   * Construct a new YArray containing the specified items.
+   * @template T
+   * @param {Array<T>} items
+   * @return {YArray<T>}
+   */
+  static from (items) {
+    const a = new YArray()
+    a.push(items)
+    return a
+  }
+
+  /**
+   * Integrate this type into the Yjs instance.
+   *
+   * * Save this struct in the os
+   * * This type is sent to other client
+   * * Observer functions are fired
+   *
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
+   */
+  _integrate (y, item) {
+    super._integrate(y, item)
+    this.insert(0, /** @type {Array<any>} */ (this._prelimContent))
+    this._prelimContent = null
+  }
+
+  _copy () {
+    return new YArray()
+  }
+
+  /**
+   * @return {YArray<T>}
+   */
+  clone () {
+    const arr = new YArray()
+    arr.insert(0, this.toArray().map(el =>
+      el instanceof AbstractType ? el.clone() : el
+    ))
+    return arr
+  }
+
+  get length () {
+    return this._prelimContent === null ? this._length : this._prelimContent.length
+  }
+
+  /**
+   * Creates YArrayEvent and calls observers.
+   *
+   * @param {Transaction} transaction
+   * @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
+   */
+  _callObserver (transaction, parentSubs) {
+    super._callObserver(transaction, parentSubs)
+    callTypeObservers(this, transaction, new YArrayEvent(this, transaction))
+  }
+
+  /**
+   * Inserts new content at an index.
+   *
+   * Important: This function expects an array of content. Not just a content
+   * object. The reason for this "weirdness" is that inserting several elements
+   * is very efficient when it is done as a single operation.
+   *
+   * @example
+   *  // Insert character 'a' at position 0
+   *  yarray.insert(0, ['a'])
+   *  // Insert numbers 1, 2 at position 1
+   *  yarray.insert(1, [1, 2])
+   *
+   * @param {number} index The index to insert content at.
+   * @param {Array<T>} content The array of content
+   */
+  insert (index, content) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListInsertGenerics(transaction, this, index, content)
+      })
+    } else {
+      /** @type {Array<any>} */ (this._prelimContent).splice(index, 0, ...content)
+    }
+  }
+
+  /**
+   * Appends content to this YArray.
+   *
+   * @param {Array<T>} content Array of content to append.
+   */
+  push (content) {
+    this.insert(this.length, content)
+  }
+
+  /**
+   * Preppends content to this YArray.
+   *
+   * @param {Array<T>} content Array of content to preppend.
+   */
+  unshift (content) {
+    this.insert(0, content)
+  }
+
+  /**
+   * Deletes elements starting from an index.
+   *
+   * @param {number} index Index at which to start deleting elements
+   * @param {number} length The number of elements to remove. Defaults to 1.
+   */
+  delete (index, length = 1) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListDelete(transaction, this, index, length)
+      })
+    } else {
+      /** @type {Array<any>} */ (this._prelimContent).splice(index, length)
+    }
+  }
+
+  /**
+   * Returns the i-th element from a YArray.
+   *
+   * @param {number} index The index of the element to return from the YArray
+   * @return {T}
+   */
+  get (index) {
+    return typeListGet(this, index)
+  }
+
+  /**
+   * Transforms this YArray to a JavaScript Array.
+   *
+   * @return {Array<T>}
+   */
+  toArray () {
+    return typeListToArray(this)
+  }
+
+  /**
+   * Transforms this YArray to a JavaScript Array.
+   *
+   * @param {number} [start]
+   * @param {number} [end]
+   * @return {Array<T>}
+   */
+  slice (start = 0, end = this.length) {
+    return typeListSlice(this, start, end)
+  }
+
+  /**
+   * Transforms this Shared Type to a JSON object.
+   *
+   * @return {Array<any>}
+   */
+  toJSON () {
+    return this.map(c => c instanceof AbstractType ? c.toJSON() : c)
+  }
+
+  /**
+   * Returns an Array with the result of calling a provided function on every
+   * element of this YArray.
+   *
+   * @template M
+   * @param {function(T,number,YArray<T>):M} f Function that produces an element of the new Array
+   * @return {Array<M>} A new array with each element being the result of the
+   *                 callback function
+   */
+  map (f) {
+    return typeListMap(this, /** @type {any} */ (f))
+  }
+
+  /**
+   * Executes a provided function on once on overy element of this YArray.
+   *
+   * @param {function(T,number,YArray<T>):void} f A function to execute on every element of this YArray.
+   */
+  forEach (f) {
+    typeListForEach(this, f)
+  }
+
+  /**
+   * @return {IterableIterator<T>}
+   */
+  [Symbol.iterator] () {
+    return typeListCreateIterator(this)
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   */
+  _write (encoder) {
+    encoder.writeTypeRef(YArrayRefID)
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ *
+ * @private
+ * @function
+ */
+export const readYArray = decoder => new YArray()

src/types/YMap.js

@@ -0,0 +1,269 @@
+
+/**
+ * @module YMap
+ */
+
+import {
+  YEvent,
+  AbstractType,
+  typeMapDelete,
+  typeMapSet,
+  typeMapGet,
+  typeMapHas,
+  createMapIterator,
+  YMapRefID,
+  callTypeObservers,
+  transact,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
+} from '../internals.js'
+
+import * as iterator from 'lib0/iterator'
+
+/**
+ * @template T
+ * Event that describes the changes on a YMap.
+ */
+export class YMapEvent extends YEvent {
+  /**
+   * @param {YMap<T>} ymap The YArray that changed.
+   * @param {Transaction} transaction
+   * @param {Set<any>} subs The keys that changed.
+   */
+  constructor (ymap, transaction, subs) {
+    super(ymap, transaction)
+    this.keysChanged = subs
+  }
+}
+
+/**
+ * @template MapType
+ * A shared Map implementation.
+ *
+ * @extends AbstractType<YMapEvent<MapType>>
+ * @implements {Iterable<MapType>}
+ */
+export class YMap extends AbstractType {
+  /**
+   *
+   * @param {Iterable<readonly [string, any]>=} entries - an optional iterable to initialize the YMap
+   */
+  constructor (entries) {
+    super()
+    /**
+     * @type {Map<string,any>?}
+     * @private
+     */
+    this._prelimContent = null
+
+    if (entries === undefined) {
+      this._prelimContent = new Map()
+    } else {
+      this._prelimContent = new Map(entries)
+    }
+  }
+
+  /**
+   * Integrate this type into the Yjs instance.
+   *
+   * * Save this struct in the os
+   * * This type is sent to other client
+   * * Observer functions are fired
+   *
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
+   */
+  _integrate (y, item) {
+    super._integrate(y, item)
+    ;/** @type {Map<string, any>} */ (this._prelimContent).forEach((value, key) => {
+      this.set(key, value)
+    })
+    this._prelimContent = null
+  }
+
+  _copy () {
+    return new YMap()
+  }
+
+  /**
+   * @return {YMap<MapType>}
+   */
+  clone () {
+    const map = new YMap()
+    this.forEach((value, key) => {
+      map.set(key, value instanceof AbstractType ? value.clone() : value)
+    })
+    return map
+  }
+
+  /**
+   * Creates YMapEvent and calls observers.
+   *
+   * @param {Transaction} transaction
+   * @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
+   */
+  _callObserver (transaction, parentSubs) {
+    callTypeObservers(this, transaction, new YMapEvent(this, transaction, parentSubs))
+  }
+
+  /**
+   * Transforms this Shared Type to a JSON object.
+   *
+   * @return {Object<string,any>}
+   */
+  toJSON () {
+    /**
+     * @type {Object<string,MapType>}
+     */
+    const map = {}
+    this._map.forEach((item, key) => {
+      if (!item.deleted) {
+        const v = item.content.getContent()[item.length - 1]
+        map[key] = v instanceof AbstractType ? v.toJSON() : v
+      }
+    })
+    return map
+  }
+
+  /**
+   * Returns the size of the YMap (count of key/value pairs)
+   *
+   * @return {number}
+   */
+  get size () {
+    return [...createMapIterator(this._map)].length
+  }
+
+  /**
+   * Returns the keys for each element in the YMap Type.
+   *
+   * @return {IterableIterator<string>}
+   */
+  keys () {
+    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[0])
+  }
+
+  /**
+   * Returns the values for each element in the YMap Type.
+   *
+   * @return {IterableIterator<any>}
+   */
+  values () {
+    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => v[1].content.getContent()[v[1].length - 1])
+  }
+
+  /**
+   * Returns an Iterator of [key, value] pairs
+   *
+   * @return {IterableIterator<any>}
+   */
+  entries () {
+    return iterator.iteratorMap(createMapIterator(this._map), /** @param {any} v */ v => [v[0], v[1].content.getContent()[v[1].length - 1]])
+  }
+
+  /**
+   * Executes a provided function on once on every key-value pair.
+   *
+   * @param {function(MapType,string,YMap<MapType>):void} f A function to execute on every element of this YArray.
+   */
+  forEach (f) {
+    /**
+     * @type {Object<string,MapType>}
+     */
+    const map = {}
+    this._map.forEach((item, key) => {
+      if (!item.deleted) {
+        f(item.content.getContent()[item.length - 1], key, this)
+      }
+    })
+    return map
+  }
+
+  /**
+   * @return {IterableIterator<MapType>}
+   */
+  [Symbol.iterator] () {
+    return this.entries()
+  }
+
+  /**
+   * Remove a specified element from this YMap.
+   *
+   * @param {string} key The key of the element to remove.
+   */
+  delete (key) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeMapDelete(transaction, this, key)
+      })
+    } else {
+      /** @type {Map<string, any>} */ (this._prelimContent).delete(key)
+    }
+  }
+
+  /**
+   * Adds or updates an element with a specified key and value.
+   *
+   * @param {string} key The key of the element to add to this YMap
+   * @param {MapType} value The value of the element to add
+   */
+  set (key, value) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeMapSet(transaction, this, key, value)
+      })
+    } else {
+      /** @type {Map<string, any>} */ (this._prelimContent).set(key, value)
+    }
+    return value
+  }
+
+  /**
+   * Returns a specified element from this YMap.
+   *
+   * @param {string} key
+   * @return {MapType|undefined}
+   */
+  get (key) {
+    return /** @type {any} */ (typeMapGet(this, key))
+  }
+
+  /**
+   * Returns a boolean indicating whether the specified key exists or not.
+   *
+   * @param {string} key The key to test.
+   * @return {boolean}
+   */
+  has (key) {
+    return typeMapHas(this, key)
+  }
+
+  /**
+   * Removes all elements from this YMap.
+   */
+  clear () {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        this.forEach(function (value, key, map) {
+          typeMapDelete(transaction, map, key)
+        })
+      })
+    } else {
+      /** @type {Map<string, any>} */ (this._prelimContent).clear()
+    }
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   */
+  _write (encoder) {
+    encoder.writeTypeRef(YMapRefID)
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ *
+ * @private
+ * @function
+ */
+export const readYMap = decoder => new YMap()

src/types/YXmlElement.js

@@ -0,0 +1,238 @@
+
+import {
+  YXmlFragment,
+  transact,
+  typeMapDelete,
+  typeMapHas,
+  typeMapSet,
+  typeMapGet,
+  typeMapGetAll,
+  typeListForEach,
+  YXmlElementRefID,
+  YXmlText, ContentType, AbstractType, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Snapshot, Doc, Item // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * An YXmlElement imitates the behavior of a
+ * {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}.
+ *
+ * * An YXmlElement has attributes (key value pairs)
+ * * An YXmlElement has childElements that must inherit from YXmlElement
+ */
+export class YXmlElement extends YXmlFragment {
+  constructor (nodeName = 'UNDEFINED') {
+    super()
+    this.nodeName = nodeName
+    /**
+     * @type {Map<string, any>|null}
+     */
+    this._prelimAttrs = new Map()
+  }
+
+  /**
+   * @type {YXmlElement|YXmlText|null}
+   */
+  get nextSibling () {
+    const n = this._item ? this._item.next : null
+    return n ? /** @type {YXmlElement|YXmlText} */ (/** @type {ContentType} */ (n.content).type) : null
+  }
+
+  /**
+   * @type {YXmlElement|YXmlText|null}
+   */
+  get prevSibling () {
+    const n = this._item ? this._item.prev : null
+    return n ? /** @type {YXmlElement|YXmlText} */ (/** @type {ContentType} */ (n.content).type) : null
+  }
+
+  /**
+   * Integrate this type into the Yjs instance.
+   *
+   * * Save this struct in the os
+   * * This type is sent to other client
+   * * Observer functions are fired
+   *
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
+   */
+  _integrate (y, item) {
+    super._integrate(y, item)
+    ;(/** @type {Map<string, any>} */ (this._prelimAttrs)).forEach((value, key) => {
+      this.setAttribute(key, value)
+    })
+    this._prelimAttrs = null
+  }
+
+  /**
+   * Creates an Item with the same effect as this Item (without position effect)
+   *
+   * @return {YXmlElement}
+   */
+  _copy () {
+    return new YXmlElement(this.nodeName)
+  }
+
+  /**
+   * @return {YXmlElement}
+   */
+  clone () {
+    const el = new YXmlElement(this.nodeName)
+    const attrs = this.getAttributes()
+    for (const key in attrs) {
+      el.setAttribute(key, attrs[key])
+    }
+    // @ts-ignore
+    el.insert(0, this.toArray().map(item => item instanceof AbstractType ? item.clone() : item))
+    return el
+  }
+
+  /**
+   * Returns the XML serialization of this YXmlElement.
+   * The attributes are ordered by attribute-name, so you can easily use this
+   * method to compare YXmlElements
+   *
+   * @return {string} The string representation of this type.
+   *
+   * @public
+   */
+  toString () {
+    const attrs = this.getAttributes()
+    const stringBuilder = []
+    const keys = []
+    for (const key in attrs) {
+      keys.push(key)
+    }
+    keys.sort()
+    const keysLen = keys.length
+    for (let i = 0; i < keysLen; i++) {
+      const key = keys[i]
+      stringBuilder.push(key + '="' + attrs[key] + '"')
+    }
+    const nodeName = this.nodeName.toLocaleLowerCase()
+    const attrsString = stringBuilder.length > 0 ? ' ' + stringBuilder.join(' ') : ''
+    return `<${nodeName}${attrsString}>${super.toString()}</${nodeName}>`
+  }
+
+  /**
+   * Removes an attribute from this YXmlElement.
+   *
+   * @param {String} attributeName The attribute name that is to be removed.
+   *
+   * @public
+   */
+  removeAttribute (attributeName) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeMapDelete(transaction, this, attributeName)
+      })
+    } else {
+      /** @type {Map<string,any>} */ (this._prelimAttrs).delete(attributeName)
+    }
+  }
+
+  /**
+   * Sets or updates an attribute.
+   *
+   * @param {String} attributeName The attribute name that is to be set.
+   * @param {String} attributeValue The attribute value that is to be set.
+   *
+   * @public
+   */
+  setAttribute (attributeName, attributeValue) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeMapSet(transaction, this, attributeName, attributeValue)
+      })
+    } else {
+      /** @type {Map<string, any>} */ (this._prelimAttrs).set(attributeName, attributeValue)
+    }
+  }
+
+  /**
+   * Returns an attribute value that belongs to the attribute name.
+   *
+   * @param {String} attributeName The attribute name that identifies the
+   *                               queried value.
+   * @return {String} The queried attribute value.
+   *
+   * @public
+   */
+  getAttribute (attributeName) {
+    return /** @type {any} */ (typeMapGet(this, attributeName))
+  }
+
+  /**
+   * Returns whether an attribute exists
+   *
+   * @param {String} attributeName The attribute name to check for existence.
+   * @return {boolean} whether the attribute exists.
+   *
+   * @public
+   */
+  hasAttribute (attributeName) {
+    return /** @type {any} */ (typeMapHas(this, attributeName))
+  }
+
+  /**
+   * Returns all attribute name/value pairs in a JSON Object.
+   *
+   * @param {Snapshot} [snapshot]
+   * @return {Object<string, any>} A JSON Object that describes the attributes.
+   *
+   * @public
+   */
+  getAttributes (snapshot) {
+    return typeMapGetAll(this)
+  }
+
+  /**
+   * Creates a Dom Element that mirrors this YXmlElement.
+   *
+   * @param {Document} [_document=document] The document object (you must define
+   *                                        this when calling this method in
+   *                                        nodejs)
+   * @param {Object<string, any>} [hooks={}] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {any} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type.
+   * @return {Node} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDOM (_document = document, hooks = {}, binding) {
+    const dom = _document.createElement(this.nodeName)
+    const attrs = this.getAttributes()
+    for (const key in attrs) {
+      dom.setAttribute(key, attrs[key])
+    }
+    typeListForEach(this, yxml => {
+      dom.appendChild(yxml.toDOM(_document, hooks, binding))
+    })
+    if (binding !== undefined) {
+      binding._createAssociation(dom, this)
+    }
+    return dom
+  }
+
+  /**
+   * Transform the properties of this type to binary and write it to an
+   * BinaryEncoder.
+   *
+   * This is called when this Item is sent to a remote peer.
+   *
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder The encoder to write data to.
+   */
+  _write (encoder) {
+    encoder.writeTypeRef(YXmlElementRefID)
+    encoder.writeKey(this.nodeName)
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {YXmlElement}
+ *
+ * @function
+ */
+export const readYXmlElement = decoder => new YXmlElement(decoder.readKey())

src/types/YXmlEvent.js

@@ -0,0 +1,39 @@
+
+import {
+  YEvent,
+  YXmlText, YXmlElement, YXmlFragment, Transaction // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * An Event that describes changes on a YXml Element or Yxml Fragment
+ */
+export class YXmlEvent extends YEvent {
+  /**
+   * @param {YXmlElement|YXmlText|YXmlFragment} target The target on which the event is created.
+   * @param {Set<string|null>} subs The set of changed attributes. `null` is included if the
+   *                   child list changed.
+   * @param {Transaction} transaction The transaction instance with wich the
+   *                                  change was created.
+   */
+  constructor (target, subs, transaction) {
+    super(target, transaction)
+    /**
+     * Whether the children changed.
+     * @type {Boolean}
+     * @private
+     */
+    this.childListChanged = false
+    /**
+     * Set of all changed attributes.
+     * @type {Set<string>}
+     */
+    this.attributesChanged = new Set()
+    subs.forEach((sub) => {
+      if (sub === null) {
+        this.childListChanged = true
+      } else {
+        this.attributesChanged.add(sub)
+      }
+    })
+  }
+}

src/types/YXmlFragment.js

@@ -0,0 +1,427 @@
+/**
+ * @module YXml
+ */
+
+import {
+  YXmlEvent,
+  YXmlElement,
+  AbstractType,
+  typeListMap,
+  typeListForEach,
+  typeListInsertGenerics,
+  typeListInsertGenericsAfter,
+  typeListDelete,
+  typeListToArray,
+  YXmlFragmentRefID,
+  callTypeObservers,
+  transact,
+  typeListGet,
+  typeListSlice,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, ContentType, Transaction, Item, YXmlText, YXmlHook, Snapshot // eslint-disable-line
+} from '../internals.js'
+
+import * as error from 'lib0/error'
+
+/**
+ * Define the elements to which a set of CSS queries apply.
+ * {@link https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Selectors|CSS_Selectors}
+ *
+ * @example
+ *   query = '.classSelector'
+ *   query = 'nodeSelector'
+ *   query = '#idSelector'
+ *
+ * @typedef {string} CSS_Selector
+ */
+
+/**
+ * Dom filter function.
+ *
+ * @callback domFilter
+ * @param {string} nodeName The nodeName of the element
+ * @param {Map} attributes The map of attributes.
+ * @return {boolean} Whether to include the Dom node in the YXmlElement.
+ */
+
+/**
+ * Represents a subset of the nodes of a YXmlElement / YXmlFragment and a
+ * position within them.
+ *
+ * Can be created with {@link YXmlFragment#createTreeWalker}
+ *
+ * @public
+ * @implements {Iterable<YXmlElement|YXmlText|YXmlElement|YXmlHook>}
+ */
+export class YXmlTreeWalker {
+  /**
+   * @param {YXmlFragment | YXmlElement} root
+   * @param {function(AbstractType<any>):boolean} [f]
+   */
+  constructor (root, f = () => true) {
+    this._filter = f
+    this._root = root
+    /**
+     * @type {Item}
+     */
+    this._currentNode = /** @type {Item} */ (root._start)
+    this._firstCall = true
+  }
+
+  [Symbol.iterator] () {
+    return this
+  }
+
+  /**
+   * Get the next node.
+   *
+   * @return {IteratorResult<YXmlElement|YXmlText|YXmlHook>} The next node.
+   *
+   * @public
+   */
+  next () {
+    /**
+     * @type {Item|null}
+     */
+    let n = this._currentNode
+    let type = n && n.content && /** @type {any} */ (n.content).type
+    if (n !== null && (!this._firstCall || n.deleted || !this._filter(type))) { // if first call, we check if we can use the first item
+      do {
+        type = /** @type {any} */ (n.content).type
+        if (!n.deleted && (type.constructor === YXmlElement || type.constructor === YXmlFragment) && type._start !== null) {
+          // walk down in the tree
+          n = type._start
+        } else {
+          // walk right or up in the tree
+          while (n !== null) {
+            if (n.right !== null) {
+              n = n.right
+              break
+            } else if (n.parent === this._root) {
+              n = null
+            } else {
+              n = /** @type {AbstractType<any>} */ (n.parent)._item
+            }
+          }
+        }
+      } while (n !== null && (n.deleted || !this._filter(/** @type {ContentType} */ (n.content).type)))
+    }
+    this._firstCall = false
+    if (n === null) {
+      // @ts-ignore
+      return { value: undefined, done: true }
+    }
+    this._currentNode = n
+    return { value: /** @type {any} */ (n.content).type, done: false }
+  }
+}
+
+/**
+ * Represents a list of {@link YXmlElement}.and {@link YXmlText} types.
+ * A YxmlFragment is similar to a {@link YXmlElement}, but it does not have a
+ * nodeName and it does not have attributes. Though it can be bound to a DOM
+ * element - in this case the attributes and the nodeName are not shared.
+ *
+ * @public
+ * @extends AbstractType<YXmlEvent>
+ */
+export class YXmlFragment extends AbstractType {
+  constructor () {
+    super()
+    /**
+     * @type {Array<any>|null}
+     */
+    this._prelimContent = []
+  }
+
+  /**
+   * @type {YXmlElement|YXmlText|null}
+   */
+  get firstChild () {
+    const first = this._first
+    return first ? first.content.getContent()[0] : null
+  }
+
+  /**
+   * Integrate this type into the Yjs instance.
+   *
+   * * Save this struct in the os
+   * * This type is sent to other client
+   * * Observer functions are fired
+   *
+   * @param {Doc} y The Yjs instance
+   * @param {Item} item
+   */
+  _integrate (y, item) {
+    super._integrate(y, item)
+    this.insert(0, /** @type {Array<any>} */ (this._prelimContent))
+    this._prelimContent = null
+  }
+
+  _copy () {
+    return new YXmlFragment()
+  }
+
+  /**
+   * @return {YXmlFragment}
+   */
+  clone () {
+    const el = new YXmlFragment()
+    // @ts-ignore
+    el.insert(0, this.toArray().map(item => item instanceof AbstractType ? item.clone() : item))
+    return el
+  }
+
+  get length () {
+    return this._prelimContent === null ? this._length : this._prelimContent.length
+  }
+
+  /**
+   * Create a subtree of childNodes.
+   *
+   * @example
+   * const walker = elem.createTreeWalker(dom => dom.nodeName === 'div')
+   * for (let node in walker) {
+   *   // `node` is a div node
+   *   nop(node)
+   * }
+   *
+   * @param {function(AbstractType<any>):boolean} filter Function that is called on each child element and
+   *                          returns a Boolean indicating whether the child
+   *                          is to be included in the subtree.
+   * @return {YXmlTreeWalker} A subtree and a position within it.
+   *
+   * @public
+   */
+  createTreeWalker (filter) {
+    return new YXmlTreeWalker(this, filter)
+  }
+
+  /**
+   * Returns the first YXmlElement that matches the query.
+   * Similar to DOM's {@link querySelector}.
+   *
+   * Query support:
+   *   - tagname
+   * TODO:
+   *   - id
+   *   - attribute
+   *
+   * @param {CSS_Selector} query The query on the children.
+   * @return {YXmlElement|YXmlText|YXmlHook|null} The first element that matches the query or null.
+   *
+   * @public
+   */
+  querySelector (query) {
+    query = query.toUpperCase()
+    // @ts-ignore
+    const iterator = new YXmlTreeWalker(this, element => element.nodeName && element.nodeName.toUpperCase() === query)
+    const next = iterator.next()
+    if (next.done) {
+      return null
+    } else {
+      return next.value
+    }
+  }
+
+  /**
+   * Returns all YXmlElements that match the query.
+   * Similar to Dom's {@link querySelectorAll}.
+   *
+   * @todo Does not yet support all queries. Currently only query by tagName.
+   *
+   * @param {CSS_Selector} query The query on the children
+   * @return {Array<YXmlElement|YXmlText|YXmlHook|null>} The elements that match this query.
+   *
+   * @public
+   */
+  querySelectorAll (query) {
+    query = query.toUpperCase()
+    // @ts-ignore
+    return Array.from(new YXmlTreeWalker(this, element => element.nodeName && element.nodeName.toUpperCase() === query))
+  }
+
+  /**
+   * Creates YXmlEvent and calls observers.
+   *
+   * @param {Transaction} transaction
+   * @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
+   */
+  _callObserver (transaction, parentSubs) {
+    callTypeObservers(this, transaction, new YXmlEvent(this, parentSubs, transaction))
+  }
+
+  /**
+   * Get the string representation of all the children of this YXmlFragment.
+   *
+   * @return {string} The string representation of all children.
+   */
+  toString () {
+    return typeListMap(this, xml => xml.toString()).join('')
+  }
+
+  /**
+   * @return {string}
+   */
+  toJSON () {
+    return this.toString()
+  }
+
+  /**
+   * Creates a Dom Element that mirrors this YXmlElement.
+   *
+   * @param {Document} [_document=document] The document object (you must define
+   *                                        this when calling this method in
+   *                                        nodejs)
+   * @param {Object<string, any>} [hooks={}] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {any} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type.
+   * @return {Node} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDOM (_document = document, hooks = {}, binding) {
+    const fragment = _document.createDocumentFragment()
+    if (binding !== undefined) {
+      binding._createAssociation(fragment, this)
+    }
+    typeListForEach(this, xmlType => {
+      fragment.insertBefore(xmlType.toDOM(_document, hooks, binding), null)
+    })
+    return fragment
+  }
+
+  /**
+   * Inserts new content at an index.
+   *
+   * @example
+   *  // Insert character 'a' at position 0
+   *  xml.insert(0, [new Y.XmlText('text')])
+   *
+   * @param {number} index The index to insert content at
+   * @param {Array<YXmlElement|YXmlText>} content The array of content
+   */
+  insert (index, content) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListInsertGenerics(transaction, this, index, content)
+      })
+    } else {
+      // @ts-ignore _prelimContent is defined because this is not yet integrated
+      this._prelimContent.splice(index, 0, ...content)
+    }
+  }
+
+  /**
+   * Inserts new content at an index.
+   *
+   * @example
+   *  // Insert character 'a' at position 0
+   *  xml.insert(0, [new Y.XmlText('text')])
+   *
+   * @param {null|Item|YXmlElement|YXmlText} ref The index to insert content at
+   * @param {Array<YXmlElement|YXmlText>} content The array of content
+   */
+  insertAfter (ref, content) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        const refItem = (ref && ref instanceof AbstractType) ? ref._item : ref
+        typeListInsertGenericsAfter(transaction, this, refItem, content)
+      })
+    } else {
+      const pc = /** @type {Array<any>} */ (this._prelimContent)
+      const index = ref === null ? 0 : pc.findIndex(el => el === ref) + 1
+      if (index === 0 && ref !== null) {
+        throw error.create('Reference item not found')
+      }
+      pc.splice(index, 0, ...content)
+    }
+  }
+
+  /**
+   * Deletes elements starting from an index.
+   *
+   * @param {number} index Index at which to start deleting elements
+   * @param {number} [length=1] The number of elements to remove. Defaults to 1.
+   */
+  delete (index, length = 1) {
+    if (this.doc !== null) {
+      transact(this.doc, transaction => {
+        typeListDelete(transaction, this, index, length)
+      })
+    } else {
+      // @ts-ignore _prelimContent is defined because this is not yet integrated
+      this._prelimContent.splice(index, length)
+    }
+  }
+
+  /**
+   * Transforms this YArray to a JavaScript Array.
+   *
+   * @return {Array<YXmlElement|YXmlText|YXmlHook>}
+   */
+  toArray () {
+    return typeListToArray(this)
+  }
+
+  /**
+   * Appends content to this YArray.
+   *
+   * @param {Array<YXmlElement|YXmlText>} content Array of content to append.
+   */
+  push (content) {
+    this.insert(this.length, content)
+  }
+
+  /**
+   * Preppends content to this YArray.
+   *
+   * @param {Array<YXmlElement|YXmlText>} content Array of content to preppend.
+   */
+  unshift (content) {
+    this.insert(0, content)
+  }
+
+  /**
+   * Returns the i-th element from a YArray.
+   *
+   * @param {number} index The index of the element to return from the YArray
+   * @return {YXmlElement|YXmlText}
+   */
+  get (index) {
+    return typeListGet(this, index)
+  }
+
+  /**
+   * Transforms this YArray to a JavaScript Array.
+   *
+   * @param {number} [start]
+   * @param {number} [end]
+   * @return {Array<YXmlElement|YXmlText>}
+   */
+  slice (start = 0, end = this.length) {
+    return typeListSlice(this, start, end)
+  }
+
+  /**
+   * Transform the properties of this type to binary and write it to an
+   * BinaryEncoder.
+   *
+   * This is called when this Item is sent to a remote peer.
+   *
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder The encoder to write data to.
+   */
+  _write (encoder) {
+    encoder.writeTypeRef(YXmlFragmentRefID)
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {YXmlFragment}
+ *
+ * @private
+ * @function
+ */
+export const readYXmlFragment = decoder => new YXmlFragment()

src/types/YXmlHook.js

@@ -0,0 +1,95 @@
+
+import {
+  YMap,
+  YXmlHookRefID,
+  UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2 // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * You can manage binding to a custom type with YXmlHook.
+ *
+ * @extends {YMap<any>}
+ */
+export class YXmlHook extends YMap {
+  /**
+   * @param {string} hookName nodeName of the Dom Node.
+   */
+  constructor (hookName) {
+    super()
+    /**
+     * @type {string}
+     */
+    this.hookName = hookName
+  }
+
+  /**
+   * Creates an Item with the same effect as this Item (without position effect)
+   */
+  _copy () {
+    return new YXmlHook(this.hookName)
+  }
+
+  /**
+   * @return {YXmlHook}
+   */
+  clone () {
+    const el = new YXmlHook(this.hookName)
+    this.forEach((value, key) => {
+      el.set(key, value)
+    })
+    return el
+  }
+
+  /**
+   * Creates a Dom Element that mirrors this YXmlElement.
+   *
+   * @param {Document} [_document=document] The document object (you must define
+   *                                        this when calling this method in
+   *                                        nodejs)
+   * @param {Object.<string, any>} [hooks] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {any} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type
+   * @return {Element} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDOM (_document = document, hooks = {}, binding) {
+    const hook = hooks[this.hookName]
+    let dom
+    if (hook !== undefined) {
+      dom = hook.createDom(this)
+    } else {
+      dom = document.createElement(this.hookName)
+    }
+    dom.setAttribute('data-yjs-hook', this.hookName)
+    if (binding !== undefined) {
+      binding._createAssociation(dom, this)
+    }
+    return dom
+  }
+
+  /**
+   * Transform the properties of this type to binary and write it to an
+   * BinaryEncoder.
+   *
+   * This is called when this Item is sent to a remote peer.
+   *
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder The encoder to write data to.
+   */
+  _write (encoder) {
+    encoder.writeTypeRef(YXmlHookRefID)
+    encoder.writeKey(this.hookName)
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {YXmlHook}
+ *
+ * @private
+ * @function
+ */
+export const readYXmlHook = decoder =>
+  new YXmlHook(decoder.readKey())

src/types/YXmlText.js

@@ -0,0 +1,121 @@
+
+import {
+  YText,
+  YXmlTextRefID,
+  ContentType, YXmlElement, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * Represents text in a Dom Element. In the future this type will also handle
+ * simple formatting information like bold and italic.
+ */
+export class YXmlText extends YText {
+  /**
+   * @type {YXmlElement|YXmlText|null}
+   */
+  get nextSibling () {
+    const n = this._item ? this._item.next : null
+    return n ? /** @type {YXmlElement|YXmlText} */ (/** @type {ContentType} */ (n.content).type) : null
+  }
+
+  /**
+   * @type {YXmlElement|YXmlText|null}
+   */
+  get prevSibling () {
+    const n = this._item ? this._item.prev : null
+    return n ? /** @type {YXmlElement|YXmlText} */ (/** @type {ContentType} */ (n.content).type) : null
+  }
+
+  _copy () {
+    return new YXmlText()
+  }
+
+  /**
+   * @return {YXmlText}
+   */
+  clone () {
+    const text = new YXmlText()
+    text.applyDelta(this.toDelta())
+    return text
+  }
+
+  /**
+   * Creates a Dom Element that mirrors this YXmlText.
+   *
+   * @param {Document} [_document=document] The document object (you must define
+   *                                        this when calling this method in
+   *                                        nodejs)
+   * @param {Object<string, any>} [hooks] Optional property to customize how hooks
+   *                                             are presented in the DOM
+   * @param {any} [binding] You should not set this property. This is
+   *                               used if DomBinding wants to create a
+   *                               association to the created DOM type.
+   * @return {Text} The {@link https://developer.mozilla.org/en-US/docs/Web/API/Element|Dom Element}
+   *
+   * @public
+   */
+  toDOM (_document = document, hooks, binding) {
+    const dom = _document.createTextNode(this.toString())
+    if (binding !== undefined) {
+      binding._createAssociation(dom, this)
+    }
+    return dom
+  }
+
+  toString () {
+    // @ts-ignore
+    return this.toDelta().map(delta => {
+      const nestedNodes = []
+      for (const nodeName in delta.attributes) {
+        const attrs = []
+        for (const key in delta.attributes[nodeName]) {
+          attrs.push({ key, value: delta.attributes[nodeName][key] })
+        }
+        // sort attributes to get a unique order
+        attrs.sort((a, b) => a.key < b.key ? -1 : 1)
+        nestedNodes.push({ nodeName, attrs })
+      }
+      // sort node order to get a unique order
+      nestedNodes.sort((a, b) => a.nodeName < b.nodeName ? -1 : 1)
+      // now convert to dom string
+      let str = ''
+      for (let i = 0; i < nestedNodes.length; i++) {
+        const node = nestedNodes[i]
+        str += `<${node.nodeName}`
+        for (let j = 0; j < node.attrs.length; j++) {
+          const attr = node.attrs[j]
+          str += ` ${attr.key}="${attr.value}"`
+        }
+        str += '>'
+      }
+      str += delta.insert
+      for (let i = nestedNodes.length - 1; i >= 0; i--) {
+        str += `</${nestedNodes[i].nodeName}>`
+      }
+      return str
+    }).join('')
+  }
+
+  /**
+   * @return {string}
+   */
+  toJSON () {
+    return this.toString()
+  }
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   */
+  _write (encoder) {
+    encoder.writeTypeRef(YXmlTextRefID)
+  }
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {YXmlText}
+ *
+ * @private
+ * @function
+ */
+export const readYXmlText = decoder => new YXmlText()

src/utils/AbstractConnector.js

@@ -0,0 +1,26 @@
+
+import { Observable } from 'lib0/observable'
+
+import {
+  Doc // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * This is an abstract interface that all Connectors should implement to keep them interchangeable.
+ *
+ * @note This interface is experimental and it is not advised to actually inherit this class.
+ *       It just serves as typing information.
+ *
+ * @extends {Observable<any>}
+ */
+export class AbstractConnector extends Observable {
+  /**
+   * @param {Doc} ydoc
+   * @param {any} awareness
+   */
+  constructor (ydoc, awareness) {
+    super()
+    this.doc = ydoc
+    this.awareness = awareness
+  }
+}

src/utils/DeleteSet.js

@@ -0,0 +1,326 @@
+
+import {
+  findIndexSS,
+  getState,
+  splitItem,
+  iterateStructs,
+  UpdateEncoderV2,
+  DSDecoderV1, DSEncoderV1, DSDecoderV2, DSEncoderV2, Item, GC, StructStore, Transaction, ID // eslint-disable-line
+} from '../internals.js'
+
+import * as array from 'lib0/array'
+import * as math from 'lib0/math'
+import * as map from 'lib0/map'
+import * as encoding from 'lib0/encoding'
+import * as decoding from 'lib0/decoding'
+
+export class DeleteItem {
+  /**
+   * @param {number} clock
+   * @param {number} len
+   */
+  constructor (clock, len) {
+    /**
+     * @type {number}
+     */
+    this.clock = clock
+    /**
+     * @type {number}
+     */
+    this.len = len
+  }
+}
+
+/**
+ * We no longer maintain a DeleteStore. DeleteSet is a temporary object that is created when needed.
+ * - When created in a transaction, it must only be accessed after sorting, and merging
+ *   - This DeleteSet is send to other clients
+ * - We do not create a DeleteSet when we send a sync message. The DeleteSet message is created directly from StructStore
+ * - We read a DeleteSet as part of a sync/update message. In this case the DeleteSet is already sorted and merged.
+ */
+export class DeleteSet {
+  constructor () {
+    /**
+     * @type {Map<number,Array<DeleteItem>>}
+     */
+    this.clients = new Map()
+  }
+}
+
+/**
+ * Iterate over all structs that the DeleteSet gc's.
+ *
+ * @param {Transaction} transaction
+ * @param {DeleteSet} ds
+ * @param {function(GC|Item):void} f
+ *
+ * @function
+ */
+export const iterateDeletedStructs = (transaction, ds, f) =>
+  ds.clients.forEach((deletes, clientid) => {
+    const structs = /** @type {Array<GC|Item>} */ (transaction.doc.store.clients.get(clientid))
+    for (let i = 0; i < deletes.length; i++) {
+      const del = deletes[i]
+      iterateStructs(transaction, structs, del.clock, del.len, f)
+    }
+  })
+
+/**
+ * @param {Array<DeleteItem>} dis
+ * @param {number} clock
+ * @return {number|null}
+ *
+ * @private
+ * @function
+ */
+export const findIndexDS = (dis, clock) => {
+  let left = 0
+  let right = dis.length - 1
+  while (left <= right) {
+    const midindex = math.floor((left + right) / 2)
+    const mid = dis[midindex]
+    const midclock = mid.clock
+    if (midclock <= clock) {
+      if (clock < midclock + mid.len) {
+        return midindex
+      }
+      left = midindex + 1
+    } else {
+      right = midindex - 1
+    }
+  }
+  return null
+}
+
+/**
+ * @param {DeleteSet} ds
+ * @param {ID} id
+ * @return {boolean}
+ *
+ * @private
+ * @function
+ */
+export const isDeleted = (ds, id) => {
+  const dis = ds.clients.get(id.client)
+  return dis !== undefined && findIndexDS(dis, id.clock) !== null
+}
+
+/**
+ * @param {DeleteSet} ds
+ *
+ * @private
+ * @function
+ */
+export const sortAndMergeDeleteSet = ds => {
+  ds.clients.forEach(dels => {
+    dels.sort((a, b) => a.clock - b.clock)
+    // merge items without filtering or splicing the array
+    // i is the current pointer
+    // j refers to the current insert position for the pointed item
+    // try to merge dels[i] into dels[j-1] or set dels[j]=dels[i]
+    let i, j
+    for (i = 1, j = 1; i < dels.length; i++) {
+      const left = dels[j - 1]
+      const right = dels[i]
+      if (left.clock + left.len >= right.clock) {
+        left.len = math.max(left.len, right.clock + right.len - left.clock)
+      } else {
+        if (j < i) {
+          dels[j] = right
+        }
+        j++
+      }
+    }
+    dels.length = j
+  })
+}
+
+/**
+ * @param {Array<DeleteSet>} dss
+ * @return {DeleteSet} A fresh DeleteSet
+ */
+export const mergeDeleteSets = dss => {
+  const merged = new DeleteSet()
+  for (let dssI = 0; dssI < dss.length; dssI++) {
+    dss[dssI].clients.forEach((delsLeft, client) => {
+      if (!merged.clients.has(client)) {
+        // Write all missing keys from current ds and all following.
+        // If merged already contains `client` current ds has already been added.
+        /**
+         * @type {Array<DeleteItem>}
+         */
+        const dels = delsLeft.slice()
+        for (let i = dssI + 1; i < dss.length; i++) {
+          array.appendTo(dels, dss[i].clients.get(client) || [])
+        }
+        merged.clients.set(client, dels)
+      }
+    })
+  }
+  sortAndMergeDeleteSet(merged)
+  return merged
+}
+
+/**
+ * @param {DeleteSet} ds
+ * @param {number} client
+ * @param {number} clock
+ * @param {number} length
+ *
+ * @private
+ * @function
+ */
+export const addToDeleteSet = (ds, client, clock, length) => {
+  map.setIfUndefined(ds.clients, client, () => []).push(new DeleteItem(clock, length))
+}
+
+export const createDeleteSet = () => new DeleteSet()
+
+/**
+ * @param {StructStore} ss
+ * @return {DeleteSet} Merged and sorted DeleteSet
+ *
+ * @private
+ * @function
+ */
+export const createDeleteSetFromStructStore = ss => {
+  const ds = createDeleteSet()
+  ss.clients.forEach((structs, client) => {
+    /**
+     * @type {Array<DeleteItem>}
+     */
+    const dsitems = []
+    for (let i = 0; i < structs.length; i++) {
+      const struct = structs[i]
+      if (struct.deleted) {
+        const clock = struct.id.clock
+        let len = struct.length
+        if (i + 1 < structs.length) {
+          for (let next = structs[i + 1]; i + 1 < structs.length && next.deleted; next = structs[++i + 1]) {
+            len += next.length
+          }
+        }
+        dsitems.push(new DeleteItem(clock, len))
+      }
+    }
+    if (dsitems.length > 0) {
+      ds.clients.set(client, dsitems)
+    }
+  })
+  return ds
+}
+
+/**
+ * @param {DSEncoderV1 | DSEncoderV2} encoder
+ * @param {DeleteSet} ds
+ *
+ * @private
+ * @function
+ */
+export const writeDeleteSet = (encoder, ds) => {
+  encoding.writeVarUint(encoder.restEncoder, ds.clients.size)
+  ds.clients.forEach((dsitems, client) => {
+    encoder.resetDsCurVal()
+    encoding.writeVarUint(encoder.restEncoder, client)
+    const len = dsitems.length
+    encoding.writeVarUint(encoder.restEncoder, len)
+    for (let i = 0; i < len; i++) {
+      const item = dsitems[i]
+      encoder.writeDsClock(item.clock)
+      encoder.writeDsLen(item.len)
+    }
+  })
+}
+
+/**
+ * @param {DSDecoderV1 | DSDecoderV2} decoder
+ * @return {DeleteSet}
+ *
+ * @private
+ * @function
+ */
+export const readDeleteSet = decoder => {
+  const ds = new DeleteSet()
+  const numClients = decoding.readVarUint(decoder.restDecoder)
+  for (let i = 0; i < numClients; i++) {
+    decoder.resetDsCurVal()
+    const client = decoding.readVarUint(decoder.restDecoder)
+    const numberOfDeletes = decoding.readVarUint(decoder.restDecoder)
+    if (numberOfDeletes > 0) {
+      const dsField = map.setIfUndefined(ds.clients, client, () => [])
+      for (let i = 0; i < numberOfDeletes; i++) {
+        dsField.push(new DeleteItem(decoder.readDsClock(), decoder.readDsLen()))
+      }
+    }
+  }
+  return ds
+}
+
+/**
+ * @todo YDecoder also contains references to String and other Decoders. Would make sense to exchange YDecoder.toUint8Array for YDecoder.DsToUint8Array()..
+ */
+
+/**
+ * @param {DSDecoderV1 | DSDecoderV2} decoder
+ * @param {Transaction} transaction
+ * @param {StructStore} store
+ * @return {Uint8Array|null} Returns a v2 update containing all deletes that couldn't be applied yet; or null if all deletes were applied successfully.
+ *
+ * @private
+ * @function
+ */
+export const readAndApplyDeleteSet = (decoder, transaction, store) => {
+  const unappliedDS = new DeleteSet()
+  const numClients = decoding.readVarUint(decoder.restDecoder)
+  for (let i = 0; i < numClients; i++) {
+    decoder.resetDsCurVal()
+    const client = decoding.readVarUint(decoder.restDecoder)
+    const numberOfDeletes = decoding.readVarUint(decoder.restDecoder)
+    const structs = store.clients.get(client) || []
+    const state = getState(store, client)
+    for (let i = 0; i < numberOfDeletes; i++) {
+      const clock = decoder.readDsClock()
+      const clockEnd = clock + decoder.readDsLen()
+      if (clock < state) {
+        if (state < clockEnd) {
+          addToDeleteSet(unappliedDS, client, state, clockEnd - state)
+        }
+        let index = findIndexSS(structs, clock)
+        /**
+         * We can ignore the case of GC and Delete structs, because we are going to skip them
+         * @type {Item}
+         */
+        // @ts-ignore
+        let struct = structs[index]
+        // split the first item if necessary
+        if (!struct.deleted && struct.id.clock < clock) {
+          structs.splice(index + 1, 0, splitItem(transaction, struct, clock - struct.id.clock))
+          index++ // increase we now want to use the next struct
+        }
+        while (index < structs.length) {
+          // @ts-ignore
+          struct = structs[index++]
+          if (struct.id.clock < clockEnd) {
+            if (!struct.deleted) {
+              if (clockEnd < struct.id.clock + struct.length) {
+                structs.splice(index, 0, splitItem(transaction, struct, clockEnd - struct.id.clock))
+              }
+              struct.delete(transaction)
+            }
+          } else {
+            break
+          }
+        }
+      } else {
+        addToDeleteSet(unappliedDS, client, clock, clockEnd - clock)
+      }
+    }
+  }
+  if (unappliedDS.clients.size > 0) {
+    const ds = new UpdateEncoderV2()
+    encoding.writeVarUint(ds.restEncoder, 0) // encode 0 structs
+    writeDeleteSet(ds, unappliedDS)
+    return ds.toUint8Array()
+  }
+  return null
+}

src/utils/Doc.js

@@ -0,0 +1,285 @@
+/**
+ * @module Y
+ */
+
+import {
+  StructStore,
+  AbstractType,
+  YArray,
+  YText,
+  YMap,
+  YXmlFragment,
+  transact,
+  ContentDoc, Item, Transaction, YEvent // eslint-disable-line
+} from '../internals.js'
+
+import { Observable } from 'lib0/observable'
+import * as random from 'lib0/random'
+import * as map from 'lib0/map'
+import * as array from 'lib0/array'
+
+export const generateNewClientId = random.uint32
+
+/**
+ * @typedef {Object} DocOpts
+ * @property {boolean} [DocOpts.gc=true] Disable garbage collection (default: gc=true)
+ * @property {function(Item):boolean} [DocOpts.gcFilter] Will be called before an Item is garbage collected. Return false to keep the Item.
+ * @property {string} [DocOpts.guid] Define a globally unique identifier for this document
+ * @property {string | null} [DocOpts.collectionid] Associate this document with a collection. This only plays a role if your provider has a concept of collection.
+ * @property {any} [DocOpts.meta] Any kind of meta information you want to associate with this document. If this is a subdocument, remote peers will store the meta information as well.
+ * @property {boolean} [DocOpts.autoLoad] If a subdocument, automatically load document. If this is a subdocument, remote peers will load the document as well automatically.
+ */
+
+/**
+ * A Yjs instance handles the state of shared data.
+ * @extends Observable<string>
+ */
+export class Doc extends Observable {
+  /**
+   * @param {DocOpts} [opts] configuration
+   */
+  constructor ({ guid = random.uuidv4(), collectionid = null, gc = true, gcFilter = () => true, meta = null, autoLoad = false } = {}) {
+    super()
+    this.gc = gc
+    this.gcFilter = gcFilter
+    this.clientID = generateNewClientId()
+    this.guid = guid
+    this.collectionid = collectionid
+    /**
+     * @type {Map<string, AbstractType<YEvent>>}
+     */
+    this.share = new Map()
+    this.store = new StructStore()
+    /**
+     * @type {Transaction | null}
+     */
+    this._transaction = null
+    /**
+     * @type {Array<Transaction>}
+     */
+    this._transactionCleanups = []
+    /**
+     * @type {Set<Doc>}
+     */
+    this.subdocs = new Set()
+    /**
+     * If this document is a subdocument - a document integrated into another document - then _item is defined.
+     * @type {Item?}
+     */
+    this._item = null
+    this.shouldLoad = autoLoad
+    this.autoLoad = autoLoad
+    this.meta = meta
+  }
+
+  /**
+   * Notify the parent document that you request to load data into this subdocument (if it is a subdocument).
+   *
+   * `load()` might be used in the future to request any provider to load the most current data.
+   *
+   * It is safe to call `load()` multiple times.
+   */
+  load () {
+    const item = this._item
+    if (item !== null && !this.shouldLoad) {
+      transact(/** @type {any} */ (item.parent).doc, transaction => {
+        transaction.subdocsLoaded.add(this)
+      }, null, true)
+    }
+    this.shouldLoad = true
+  }
+
+  getSubdocs () {
+    return this.subdocs
+  }
+
+  getSubdocGuids () {
+    return new Set(Array.from(this.subdocs).map(doc => doc.guid))
+  }
+
+  /**
+   * Changes that happen inside of a transaction are bundled. This means that
+   * the observer fires _after_ the transaction is finished and that all changes
+   * that happened inside of the transaction are sent as one message to the
+   * other peers.
+   *
+   * @param {function(Transaction):void} f The function that should be executed as a transaction
+   * @param {any} [origin] Origin of who started the transaction. Will be stored on transaction.origin
+   *
+   * @public
+   */
+  transact (f, origin = null) {
+    transact(this, f, origin)
+  }
+
+  /**
+   * Define a shared data type.
+   *
+   * Multiple calls of `y.get(name, TypeConstructor)` yield the same result
+   * and do not overwrite each other. I.e.
+   * `y.define(name, Y.Array) === y.define(name, Y.Array)`
+   *
+   * After this method is called, the type is also available on `y.share.get(name)`.
+   *
+   * *Best Practices:*
+   * Define all types right after the Yjs instance is created and store them in a separate object.
+   * Also use the typed methods `getText(name)`, `getArray(name)`, ..
+   *
+   * @example
+   *   const y = new Y(..)
+   *   const appState = {
+   *     document: y.getText('document')
+   *     comments: y.getArray('comments')
+   *   }
+   *
+   * @param {string} name
+   * @param {Function} TypeConstructor The constructor of the type definition. E.g. Y.Text, Y.Array, Y.Map, ...
+   * @return {AbstractType<any>} The created type. Constructed with TypeConstructor
+   *
+   * @public
+   */
+  get (name, TypeConstructor = AbstractType) {
+    const type = map.setIfUndefined(this.share, name, () => {
+      // @ts-ignore
+      const t = new TypeConstructor()
+      t._integrate(this, null)
+      return t
+    })
+    const Constr = type.constructor
+    if (TypeConstructor !== AbstractType && Constr !== TypeConstructor) {
+      if (Constr === AbstractType) {
+        // @ts-ignore
+        const t = new TypeConstructor()
+        t._map = type._map
+        type._map.forEach(/** @param {Item?} n */ n => {
+          for (; n !== null; n = n.left) {
+            // @ts-ignore
+            n.parent = t
+          }
+        })
+        t._start = type._start
+        for (let n = t._start; n !== null; n = n.right) {
+          n.parent = t
+        }
+        t._length = type._length
+        this.share.set(name, t)
+        t._integrate(this, null)
+        return t
+      } else {
+        throw new Error(`Type with the name ${name} has already been defined with a different constructor`)
+      }
+    }
+    return type
+  }
+
+  /**
+   * @template T
+   * @param {string} [name]
+   * @return {YArray<T>}
+   *
+   * @public
+   */
+  getArray (name = '') {
+    // @ts-ignore
+    return this.get(name, YArray)
+  }
+
+  /**
+   * @param {string} [name]
+   * @return {YText}
+   *
+   * @public
+   */
+  getText (name = '') {
+    // @ts-ignore
+    return this.get(name, YText)
+  }
+
+  /**
+   * @template T
+   * @param {string} [name]
+   * @return {YMap<T>}
+   *
+   * @public
+   */
+  getMap (name = '') {
+    // @ts-ignore
+    return this.get(name, YMap)
+  }
+
+  /**
+   * @param {string} [name]
+   * @return {YXmlFragment}
+   *
+   * @public
+   */
+  getXmlFragment (name = '') {
+    // @ts-ignore
+    return this.get(name, YXmlFragment)
+  }
+
+  /**
+   * Converts the entire document into a js object, recursively traversing each yjs type
+   * Doesn't log types that have not been defined (using ydoc.getType(..)).
+   *
+   * @deprecated Do not use this method and rather call toJSON directly on the shared types.
+   *
+   * @return {Object<string, any>}
+   */
+  toJSON () {
+    /**
+     * @type {Object<string, any>}
+     */
+    const doc = {}
+
+    this.share.forEach((value, key) => {
+      doc[key] = value.toJSON()
+    })
+
+    return doc
+  }
+
+  /**
+   * Emit `destroy` event and unregister all event handlers.
+   */
+  destroy () {
+    array.from(this.subdocs).forEach(subdoc => subdoc.destroy())
+    const item = this._item
+    if (item !== null) {
+      this._item = null
+      const content = /** @type {ContentDoc} */ (item.content)
+      if (item.deleted) {
+        // @ts-ignore
+        content.doc = null
+      } else {
+        content.doc = new Doc({ guid: this.guid, ...content.opts })
+        content.doc._item = item
+      }
+      transact(/** @type {any} */ (item).parent.doc, transaction => {
+        if (!item.deleted) {
+          transaction.subdocsAdded.add(content.doc)
+        }
+        transaction.subdocsRemoved.add(this)
+      }, null, true)
+    }
+    this.emit('destroyed', [true])
+    this.emit('destroy', [this])
+    super.destroy()
+  }
+
+  /**
+   * @param {string} eventName
+   * @param {function(...any):any} f
+   */
+  on (eventName, f) {
+    super.on(eventName, f)
+  }
+
+  /**
+   * @param {string} eventName
+   * @param {function} f
+   */
+  off (eventName, f) {
+    super.off(eventName, f)
+  }
+}

src/utils/EventHandler.js

@@ -0,0 +1,87 @@
+import * as f from 'lib0/function'
+
+/**
+ * General event handler implementation.
+ *
+ * @template ARG0, ARG1
+ *
+ * @private
+ */
+export class EventHandler {
+  constructor () {
+    /**
+     * @type {Array<function(ARG0, ARG1):void>}
+     */
+    this.l = []
+  }
+}
+
+/**
+ * @template ARG0,ARG1
+ * @returns {EventHandler<ARG0,ARG1>}
+ *
+ * @private
+ * @function
+ */
+export const createEventHandler = () => new EventHandler()
+
+/**
+ * Adds an event listener that is called when
+ * {@link EventHandler#callEventListeners} is called.
+ *
+ * @template ARG0,ARG1
+ * @param {EventHandler<ARG0,ARG1>} eventHandler
+ * @param {function(ARG0,ARG1):void} f The event handler.
+ *
+ * @private
+ * @function
+ */
+export const addEventHandlerListener = (eventHandler, f) =>
+  eventHandler.l.push(f)
+
+/**
+ * Removes an event listener.
+ *
+ * @template ARG0,ARG1
+ * @param {EventHandler<ARG0,ARG1>} eventHandler
+ * @param {function(ARG0,ARG1):void} f The event handler that was added with
+ *                     {@link EventHandler#addEventListener}
+ *
+ * @private
+ * @function
+ */
+export const removeEventHandlerListener = (eventHandler, f) => {
+  const l = eventHandler.l
+  const len = l.length
+  eventHandler.l = l.filter(g => f !== g)
+  if (len === eventHandler.l.length) {
+    console.error('[yjs] Tried to remove event handler that doesn\'t exist.')
+  }
+}
+
+/**
+ * Removes all event listeners.
+ * @template ARG0,ARG1
+ * @param {EventHandler<ARG0,ARG1>} eventHandler
+ *
+ * @private
+ * @function
+ */
+export const removeAllEventHandlerListeners = eventHandler => {
+  eventHandler.l.length = 0
+}
+
+/**
+ * Call all event listeners that were added via
+ * {@link EventHandler#addEventListener}.
+ *
+ * @template ARG0,ARG1
+ * @param {EventHandler<ARG0,ARG1>} eventHandler
+ * @param {ARG0} arg0
+ * @param {ARG1} arg1
+ *
+ * @private
+ * @function
+ */
+export const callEventHandlerListeners = (eventHandler, arg0, arg1) =>
+  f.callAll(eventHandler.l, [arg0, arg1])

src/utils/ID.js

@@ -0,0 +1,90 @@
+
+import { AbstractType } from '../internals.js' // eslint-disable-line
+
+import * as decoding from 'lib0/decoding'
+import * as encoding from 'lib0/encoding'
+import * as error from 'lib0/error'
+
+export class ID {
+  /**
+   * @param {number} client client id
+   * @param {number} clock unique per client id, continuous number
+   */
+  constructor (client, clock) {
+    /**
+     * Client id
+     * @type {number}
+     */
+    this.client = client
+    /**
+     * unique per client id, continuous number
+     * @type {number}
+     */
+    this.clock = clock
+  }
+}
+
+/**
+ * @param {ID | null} a
+ * @param {ID | null} b
+ * @return {boolean}
+ *
+ * @function
+ */
+export const compareIDs = (a, b) => a === b || (a !== null && b !== null && a.client === b.client && a.clock === b.clock)
+
+/**
+ * @param {number} client
+ * @param {number} clock
+ *
+ * @private
+ * @function
+ */
+export const createID = (client, clock) => new ID(client, clock)
+
+/**
+ * @param {encoding.Encoder} encoder
+ * @param {ID} id
+ *
+ * @private
+ * @function
+ */
+export const writeID = (encoder, id) => {
+  encoding.writeVarUint(encoder, id.client)
+  encoding.writeVarUint(encoder, id.clock)
+}
+
+/**
+ * Read ID.
+ * * If first varUint read is 0xFFFFFF a RootID is returned.
+ * * Otherwise an ID is returned
+ *
+ * @param {decoding.Decoder} decoder
+ * @return {ID}
+ *
+ * @private
+ * @function
+ */
+export const readID = decoder =>
+  createID(decoding.readVarUint(decoder), decoding.readVarUint(decoder))
+
+/**
+ * The top types are mapped from y.share.get(keyname) => type.
+ * `type` does not store any information about the `keyname`.
+ * This function finds the correct `keyname` for `type` and throws otherwise.
+ *
+ * @param {AbstractType<any>} type
+ * @return {string}
+ *
+ * @private
+ * @function
+ */
+export const findRootTypeKey = type => {
+  // @ts-ignore _y must be defined, otherwise unexpected case
+  for (const [key, value] of type.doc.share.entries()) {
+    if (value === type) {
+      return key
+    }
+  }
+  throw error.unexpectedCase()
+}

src/utils/PermanentUserData.js

@@ -0,0 +1,142 @@
+
+import {
+  YArray,
+  YMap,
+  readDeleteSet,
+  writeDeleteSet,
+  createDeleteSet,
+  DSEncoderV1, DSDecoderV1, ID, DeleteSet, YArrayEvent, Transaction, Doc // eslint-disable-line
+} from '../internals.js'
+
+import * as decoding from 'lib0/decoding'
+
+import { mergeDeleteSets, isDeleted } from './DeleteSet.js'
+
+export class PermanentUserData {
+  /**
+   * @param {Doc} doc
+   * @param {YMap<any>} [storeType]
+   */
+  constructor (doc, storeType = doc.getMap('users')) {
+    /**
+     * @type {Map<string,DeleteSet>}
+     */
+    const dss = new Map()
+    this.yusers = storeType
+    this.doc = doc
+    /**
+     * Maps from clientid to userDescription
+     *
+     * @type {Map<number,string>}
+     */
+    this.clients = new Map()
+    this.dss = dss
+    /**
+     * @param {YMap<any>} user
+     * @param {string} userDescription
+     */
+    const initUser = (user, userDescription) => {
+      /**
+       * @type {YArray<Uint8Array>}
+       */
+      const ds = user.get('ds')
+      const ids = user.get('ids')
+      const addClientId = /** @param {number} clientid */ clientid => this.clients.set(clientid, userDescription)
+      ds.observe(/** @param {YArrayEvent<any>} event */ event => {
+        event.changes.added.forEach(item => {
+          item.content.getContent().forEach(encodedDs => {
+            if (encodedDs instanceof Uint8Array) {
+              this.dss.set(userDescription, mergeDeleteSets([this.dss.get(userDescription) || createDeleteSet(), readDeleteSet(new DSDecoderV1(decoding.createDecoder(encodedDs)))]))
+            }
+          })
+        })
+      })
+      this.dss.set(userDescription, mergeDeleteSets(ds.map(encodedDs => readDeleteSet(new DSDecoderV1(decoding.createDecoder(encodedDs))))))
+      ids.observe(/** @param {YArrayEvent<any>} event */ event =>
+        event.changes.added.forEach(item => item.content.getContent().forEach(addClientId))
+      )
+      ids.forEach(addClientId)
+    }
+    // observe users
+    storeType.observe(event => {
+      event.keysChanged.forEach(userDescription =>
+        initUser(storeType.get(userDescription), userDescription)
+      )
+    })
+    // add intial data
+    storeType.forEach(initUser)
+  }
+
+  /**
+   * @param {Doc} doc
+   * @param {number} clientid
+   * @param {string} userDescription
+   * @param {Object} [conf]
+   * @param {function(Transaction, DeleteSet):boolean} [conf.filter]
+   */
+  setUserMapping (doc, clientid, userDescription, { filter = () => true } = {}) {
+    const users = this.yusers
+    let user = users.get(userDescription)
+    if (!user) {
+      user = new YMap()
+      user.set('ids', new YArray())
+      user.set('ds', new YArray())
+      users.set(userDescription, user)
+    }
+    user.get('ids').push([clientid])
+    users.observe(event => {
+      setTimeout(() => {
+        const userOverwrite = users.get(userDescription)
+        if (userOverwrite !== user) {
+          // user was overwritten, port all data over to the next user object
+          // @todo Experiment with Y.Sets here
+          user = userOverwrite
+          // @todo iterate over old type
+          this.clients.forEach((_userDescription, clientid) => {
+            if (userDescription === _userDescription) {
+              user.get('ids').push([clientid])
+            }
+          })
+          const encoder = new DSEncoderV1()
+          const ds = this.dss.get(userDescription)
+          if (ds) {
+            writeDeleteSet(encoder, ds)
+            user.get('ds').push([encoder.toUint8Array()])
+          }
+        }
+      }, 0)
+    })
+    doc.on('afterTransaction', /** @param {Transaction} transaction */ transaction => {
+      setTimeout(() => {
+        const yds = user.get('ds')
+        const ds = transaction.deleteSet
+        if (transaction.local && ds.clients.size > 0 && filter(transaction, ds)) {
+          const encoder = new DSEncoderV1()
+          writeDeleteSet(encoder, ds)
+          yds.push([encoder.toUint8Array()])
+        }
+      })
+    })
+  }
+
+  /**
+   * @param {number} clientid
+   * @return {any}
+   */
+  getUserByClientId (clientid) {
+    return this.clients.get(clientid) || null
+  }
+
+  /**
+   * @param {ID} id
+   * @return {string | null}
+   */
+  getUserByDeletedId (id) {
+    for (const [userDescription, ds] of this.dss.entries()) {
+      if (isDeleted(ds, id)) {
+        return userDescription
+      }
+    }
+    return null
+  }
+}

src/utils/RelativePosition.js

@@ -0,0 +1,330 @@
+
+import {
+  writeID,
+  readID,
+  compareIDs,
+  getState,
+  findRootTypeKey,
+  Item,
+  createID,
+  ContentType,
+  followRedone,
+  ID, Doc, AbstractType // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding'
+import * as decoding from 'lib0/decoding'
+import * as error from 'lib0/error'
+
+/**
+ * A relative position is based on the Yjs model and is not affected by document changes.
+ * E.g. If you place a relative position before a certain character, it will always point to this character.
+ * If you place a relative position at the end of a type, it will always point to the end of the type.
+ *
+ * A numeric position is often unsuited for user selections, because it does not change when content is inserted
+ * before or after.
+ *
+ * ```Insert(0, 'x')('a|bc') = 'xa|bc'``` Where | is the relative position.
+ *
+ * One of the properties must be defined.
+ *
+ * @example
+ *   // Current cursor position is at position 10
+ *   const relativePosition = createRelativePositionFromIndex(yText, 10)
+ *   // modify yText
+ *   yText.insert(0, 'abc')
+ *   yText.delete(3, 10)
+ *   // Compute the cursor position
+ *   const absolutePosition = createAbsolutePositionFromRelativePosition(y, relativePosition)
+ *   absolutePosition.type === yText // => true
+ *   console.log('cursor location is ' + absolutePosition.index) // => cursor location is 3
+ *
+ */
+export class RelativePosition {
+  /**
+   * @param {ID|null} type
+   * @param {string|null} tname
+   * @param {ID|null} item
+   * @param {number} assoc
+   */
+  constructor (type, tname, item, assoc = 0) {
+    /**
+     * @type {ID|null}
+     */
+    this.type = type
+    /**
+     * @type {string|null}
+     */
+    this.tname = tname
+    /**
+     * @type {ID | null}
+     */
+    this.item = item
+    /**
+     * A relative position is associated to a specific character. By default
+     * assoc >= 0, the relative position is associated to the character
+     * after the meant position.
+     * I.e. position 1 in 'ab' is associated to character 'b'.
+     *
+     * If assoc < 0, then the relative position is associated to the caharacter
+     * before the meant position.
+     *
+     * @type {number}
+     */
+    this.assoc = assoc
+  }
+}
+
+/**
+ * @param {RelativePosition} rpos
+ * @return {any}
+ */
+export const relativePositionToJSON = rpos => {
+  const json = {}
+  if (rpos.type) {
+    json.type = rpos.type
+  }
+  if (rpos.tname) {
+    json.tname = rpos.tname
+  }
+  if (rpos.item) {
+    json.item = rpos.item
+  }
+  if (rpos.assoc != null) {
+    json.assoc = rpos.assoc
+  }
+  return json
+}
+
+/**
+ * @param {any} json
+ * @return {RelativePosition}
+ *
+ * @function
+ */
+export const createRelativePositionFromJSON = json => new RelativePosition(json.type == null ? null : createID(json.type.client, json.type.clock), json.tname || null, json.item == null ? null : createID(json.item.client, json.item.clock), json.assoc == null ? 0 : json.assoc)
+
+export class AbsolutePosition {
+  /**
+   * @param {AbstractType<any>} type
+   * @param {number} index
+   * @param {number} [assoc]
+   */
+  constructor (type, index, assoc = 0) {
+    /**
+     * @type {AbstractType<any>}
+     */
+    this.type = type
+    /**
+     * @type {number}
+     */
+    this.index = index
+    this.assoc = assoc
+  }
+}
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {number} index
+ * @param {number} [assoc]
+ *
+ * @function
+ */
+export const createAbsolutePosition = (type, index, assoc = 0) => new AbsolutePosition(type, index, assoc)
+
+/**
+ * @param {AbstractType<any>} type
+ * @param {ID|null} item
+ * @param {number} [assoc]
+ *
+ * @function
+ */
+export const createRelativePosition = (type, item, assoc) => {
+  let typeid = null
+  let tname = null
+  if (type._item === null) {
+    tname = findRootTypeKey(type)
+  } else {
+    typeid = createID(type._item.id.client, type._item.id.clock)
+  }
+  return new RelativePosition(typeid, tname, item, assoc)
+}
+
+/**
+ * Create a relativePosition based on a absolute position.
+ *
+ * @param {AbstractType<any>} type The base type (e.g. YText or YArray).
+ * @param {number} index The absolute position.
+ * @param {number} [assoc]
+ * @return {RelativePosition}
+ *
+ * @function
+ */
+export const createRelativePositionFromTypeIndex = (type, index, assoc = 0) => {
+  let t = type._start
+  if (assoc < 0) {
+    // associated to the left character or the beginning of a type, increment index if possible.
+    if (index === 0) {
+      return createRelativePosition(type, null, assoc)
+    }
+    index--
+  }
+  while (t !== null) {
+    if (!t.deleted && t.countable) {
+      if (t.length > index) {
+        // case 1: found position somewhere in the linked list
+        return createRelativePosition(type, createID(t.id.client, t.id.clock + index), assoc)
+      }
+      index -= t.length
+    }
+    if (t.right === null && assoc < 0) {
+      // left-associated position, return last available id
+      return createRelativePosition(type, t.lastId, assoc)
+    }
+    t = t.right
+  }
+  return createRelativePosition(type, null, assoc)
+}
+
+/**
+ * @param {encoding.Encoder} encoder
+ * @param {RelativePosition} rpos
+ *
+ * @function
+ */
+export const writeRelativePosition = (encoder, rpos) => {
+  const { type, tname, item, assoc } = rpos
+  if (item !== null) {
+    encoding.writeVarUint(encoder, 0)
+    writeID(encoder, item)
+  } else if (tname !== null) {
+    // case 2: found position at the end of the list and type is stored in y.share
+    encoding.writeUint8(encoder, 1)
+    encoding.writeVarString(encoder, tname)
+  } else if (type !== null) {
+    // case 3: found position at the end of the list and type is attached to an item
+    encoding.writeUint8(encoder, 2)
+    writeID(encoder, type)
+  } else {
+    throw error.unexpectedCase()
+  }
+  encoding.writeVarInt(encoder, assoc)
+  return encoder
+}
+
+/**
+ * @param {RelativePosition} rpos
+ * @return {Uint8Array}
+ */
+export const encodeRelativePosition = rpos => {
+  const encoder = encoding.createEncoder()
+  writeRelativePosition(encoder, rpos)
+  return encoding.toUint8Array(encoder)
+}
+
+/**
+ * @param {decoding.Decoder} decoder
+ * @return {RelativePosition}
+ *
+ * @function
+ */
+export const readRelativePosition = decoder => {
+  let type = null
+  let tname = null
+  let itemID = null
+  switch (decoding.readVarUint(decoder)) {
+    case 0:
+      // case 1: found position somewhere in the linked list
+      itemID = readID(decoder)
+      break
+    case 1:
+      // case 2: found position at the end of the list and type is stored in y.share
+      tname = decoding.readVarString(decoder)
+      break
+    case 2: {
+      // case 3: found position at the end of the list and type is attached to an item
+      type = readID(decoder)
+    }
+  }
+  const assoc = decoding.hasContent(decoder) ? decoding.readVarInt(decoder) : 0
+  return new RelativePosition(type, tname, itemID, assoc)
+}
+
+/**
+ * @param {Uint8Array} uint8Array
+ * @return {RelativePosition}
+ */
+export const decodeRelativePosition = uint8Array => readRelativePosition(decoding.createDecoder(uint8Array))
+
+/**
+ * @param {RelativePosition} rpos
+ * @param {Doc} doc
+ * @return {AbsolutePosition|null}
+ *
+ * @function
+ */
+export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
+  const store = doc.store
+  const rightID = rpos.item
+  const typeID = rpos.type
+  const tname = rpos.tname
+  const assoc = rpos.assoc
+  let type = null
+  let index = 0
+  if (rightID !== null) {
+    if (getState(store, rightID.client) <= rightID.clock) {
+      return null
+    }
+    const res = followRedone(store, rightID)
+    const right = res.item
+    if (!(right instanceof Item)) {
+      return null
+    }
+    type = /** @type {AbstractType<any>} */ (right.parent)
+    if (type._item === null || !type._item.deleted) {
+      index = (right.deleted || !right.countable) ? 0 : (res.diff + (assoc >= 0 ? 0 : 1)) // adjust position based on left association if necessary
+      let n = right.left
+      while (n !== null) {
+        if (!n.deleted && n.countable) {
+          index += n.length
+        }
+        n = n.left
+      }
+    }
+  } else {
+    if (tname !== null) {
+      type = doc.get(tname)
+    } else if (typeID !== null) {
+      if (getState(store, typeID.client) <= typeID.clock) {
+        // type does not exist yet
+        return null
+      }
+      const { item } = followRedone(store, typeID)
+      if (item instanceof Item && item.content instanceof ContentType) {
+        type = item.content.type
+      } else {
+        // struct is garbage collected
+        return null
+      }
+    } else {
+      throw error.unexpectedCase()
+    }
+    if (assoc >= 0) {
+      index = type._length
+    } else {
+      index = 0
+    }
+  }
+  return createAbsolutePosition(type, index, rpos.assoc)
+}
+
+/**
+ * @param {RelativePosition|null} a
+ * @param {RelativePosition|null} b
+ * @return {boolean}
+ *
+ * @function
+ */
+export const compareRelativePositions = (a, b) => a === b || (
+  a !== null && b !== null && a.tname === b.tname && compareIDs(a.item, b.item) && compareIDs(a.type, b.type) && a.assoc === b.assoc
+)

src/utils/Snapshot.js

@@ -0,0 +1,201 @@
+
+import {
+  isDeleted,
+  createDeleteSetFromStructStore,
+  getStateVector,
+  getItemCleanStart,
+  iterateDeletedStructs,
+  writeDeleteSet,
+  writeStateVector,
+  readDeleteSet,
+  readStateVector,
+  createDeleteSet,
+  createID,
+  getState,
+  findIndexSS,
+  UpdateEncoderV2,
+  applyUpdateV2,
+  DSEncoderV1, DSEncoderV2, DSDecoderV1, DSDecoderV2, Transaction, Doc, DeleteSet, Item // eslint-disable-line
+} from '../internals.js'
+
+import * as map from 'lib0/map'
+import * as set from 'lib0/set'
+import * as decoding from 'lib0/decoding'
+import * as encoding from 'lib0/encoding'
+
+export class Snapshot {
+  /**
+   * @param {DeleteSet} ds
+   * @param {Map<number,number>} sv state map
+   */
+  constructor (ds, sv) {
+    /**
+     * @type {DeleteSet}
+     */
+    this.ds = ds
+    /**
+     * State Map
+     * @type {Map<number,number>}
+     */
+    this.sv = sv
+  }
+}
+
+/**
+ * @param {Snapshot} snap1
+ * @param {Snapshot} snap2
+ * @return {boolean}
+ */
+export const equalSnapshots = (snap1, snap2) => {
+  const ds1 = snap1.ds.clients
+  const ds2 = snap2.ds.clients
+  const sv1 = snap1.sv
+  const sv2 = snap2.sv
+  if (sv1.size !== sv2.size || ds1.size !== ds2.size) {
+    return false
+  }
+  for (const [key, value] of sv1.entries()) {
+    if (sv2.get(key) !== value) {
+      return false
+    }
+  }
+  for (const [client, dsitems1] of ds1.entries()) {
+    const dsitems2 = ds2.get(client) || []
+    if (dsitems1.length !== dsitems2.length) {
+      return false
+    }
+    for (let i = 0; i < dsitems1.length; i++) {
+      const dsitem1 = dsitems1[i]
+      const dsitem2 = dsitems2[i]
+      if (dsitem1.clock !== dsitem2.clock || dsitem1.len !== dsitem2.len) {
+        return false
+      }
+    }
+  }
+  return true
+}
+
+/**
+ * @param {Snapshot} snapshot
+ * @param {DSEncoderV1 | DSEncoderV2} [encoder]
+ * @return {Uint8Array}
+ */
+export const encodeSnapshotV2 = (snapshot, encoder = new DSEncoderV2()) => {
+  writeDeleteSet(encoder, snapshot.ds)
+  writeStateVector(encoder, snapshot.sv)
+  return encoder.toUint8Array()
+}
+
+/**
+ * @param {Snapshot} snapshot
+ * @return {Uint8Array}
+ */
+export const encodeSnapshot = snapshot => encodeSnapshotV2(snapshot, new DSEncoderV1())
+
+/**
+ * @param {Uint8Array} buf
+ * @param {DSDecoderV1 | DSDecoderV2} [decoder]
+ * @return {Snapshot}
+ */
+export const decodeSnapshotV2 = (buf, decoder = new DSDecoderV2(decoding.createDecoder(buf))) => {
+  return new Snapshot(readDeleteSet(decoder), readStateVector(decoder))
+}
+
+/**
+ * @param {Uint8Array} buf
+ * @return {Snapshot}
+ */
+export const decodeSnapshot = buf => decodeSnapshotV2(buf, new DSDecoderV1(decoding.createDecoder(buf)))
+
+/**
+ * @param {DeleteSet} ds
+ * @param {Map<number,number>} sm
+ * @return {Snapshot}
+ */
+export const createSnapshot = (ds, sm) => new Snapshot(ds, sm)
+
+export const emptySnapshot = createSnapshot(createDeleteSet(), new Map())
+
+/**
+ * @param {Doc} doc
+ * @return {Snapshot}
+ */
+export const snapshot = doc => createSnapshot(createDeleteSetFromStructStore(doc.store), getStateVector(doc.store))
+
+/**
+ * @param {Item} item
+ * @param {Snapshot|undefined} snapshot
+ *
+ * @protected
+ * @function
+ */
+export const isVisible = (item, snapshot) => snapshot === undefined
+  ? !item.deleted
+  : snapshot.sv.has(item.id.client) && (snapshot.sv.get(item.id.client) || 0) > item.id.clock && !isDeleted(snapshot.ds, item.id)
+
+/**
+ * @param {Transaction} transaction
+ * @param {Snapshot} snapshot
+ */
+export const splitSnapshotAffectedStructs = (transaction, snapshot) => {
+  const meta = map.setIfUndefined(transaction.meta, splitSnapshotAffectedStructs, set.create)
+  const store = transaction.doc.store
+  // check if we already split for this snapshot
+  if (!meta.has(snapshot)) {
+    snapshot.sv.forEach((clock, client) => {
+      if (clock < getState(store, client)) {
+        getItemCleanStart(transaction, createID(client, clock))
+      }
+    })
+    iterateDeletedStructs(transaction, snapshot.ds, item => {})
+    meta.add(snapshot)
+  }
+}
+
+/**
+ * @param {Doc} originDoc
+ * @param {Snapshot} snapshot
+ * @param {Doc} [newDoc] Optionally, you may define the Yjs document that receives the data from originDoc
+ * @return {Doc}
+ */
+export const createDocFromSnapshot = (originDoc, snapshot, newDoc = new Doc()) => {
+  if (originDoc.gc) {
+    // we should not try to restore a GC-ed document, because some of the restored items might have their content deleted
+    throw new Error('originDoc must not be garbage collected')
+  }
+  const { sv, ds } = snapshot
+
+  const encoder = new UpdateEncoderV2()
+  originDoc.transact(transaction => {
+    let size = 0
+    sv.forEach(clock => {
+      if (clock > 0) {
+        size++
+      }
+    })
+    encoding.writeVarUint(encoder.restEncoder, size)
+    // splitting the structs before writing them to the encoder
+    for (const [client, clock] of sv) {
+      if (clock === 0) {
+        continue
+      }
+      if (clock < getState(originDoc.store, client)) {
+        getItemCleanStart(transaction, createID(client, clock))
+      }
+      const structs = originDoc.store.clients.get(client) || []
+      const lastStructIndex = findIndexSS(structs, clock - 1)
+      // write # encoded structs
+      encoding.writeVarUint(encoder.restEncoder, lastStructIndex + 1)
+      encoder.writeClient(client)
+      // first clock written is 0
+      encoding.writeVarUint(encoder.restEncoder, 0)
+      for (let i = 0; i <= lastStructIndex; i++) {
+        structs[i].write(encoder, 0)
+      }
+    }
+    writeDeleteSet(encoder, ds)
+  })
+
+  applyUpdateV2(newDoc, encoder.toUint8Array(), 'snapshot')
+  return newDoc
+}

src/utils/StructStore.js

@@ -0,0 +1,262 @@
+
+import {
+  GC,
+  splitItem,
+  Transaction, ID, Item, DSDecoderV2 // eslint-disable-line
+} from '../internals.js'
+
+import * as math from 'lib0/math'
+import * as error from 'lib0/error'
+
+export class StructStore {
+  constructor () {
+    /**
+     * @type {Map<number,Array<GC|Item>>}
+     */
+    this.clients = new Map()
+    /**
+     * @type {null | { missing: Map<number, number>, update: Uint8Array }}
+     */
+    this.pendingStructs = null
+    /**
+     * @type {null | Uint8Array}
+     */
+    this.pendingDs = null
+  }
+}
+
+/**
+ * Return the states as a Map<client,clock>.
+ * Note that clock refers to the next expected clock id.
+ *
+ * @param {StructStore} store
+ * @return {Map<number,number>}
+ *
+ * @public
+ * @function
+ */
+export const getStateVector = store => {
+  const sm = new Map()
+  store.clients.forEach((structs, client) => {
+    const struct = structs[structs.length - 1]
+    sm.set(client, struct.id.clock + struct.length)
+  })
+  return sm
+}
+
+/**
+ * @param {StructStore} store
+ * @param {number} client
+ * @return {number}
+ *
+ * @public
+ * @function
+ */
+export const getState = (store, client) => {
+  const structs = store.clients.get(client)
+  if (structs === undefined) {
+    return 0
+  }
+  const lastStruct = structs[structs.length - 1]
+  return lastStruct.id.clock + lastStruct.length
+}
+
+/**
+ * @param {StructStore} store
+ *
+ * @private
+ * @function
+ */
+export const integretyCheck = store => {
+  store.clients.forEach(structs => {
+    for (let i = 1; i < structs.length; i++) {
+      const l = structs[i - 1]
+      const r = structs[i]
+      if (l.id.clock + l.length !== r.id.clock) {
+        throw new Error('StructStore failed integrety check')
+      }
+    }
+  })
+}
+
+/**
+ * @param {StructStore} store
+ * @param {GC|Item} struct
+ *
+ * @private
+ * @function
+ */
+export const addStruct = (store, struct) => {
+  let structs = store.clients.get(struct.id.client)
+  if (structs === undefined) {
+    structs = []
+    store.clients.set(struct.id.client, structs)
+  } else {
+    const lastStruct = structs[structs.length - 1]
+    if (lastStruct.id.clock + lastStruct.length !== struct.id.clock) {
+      throw error.unexpectedCase()
+    }
+  }
+  structs.push(struct)
+}
+
+/**
+ * Perform a binary search on a sorted array
+ * @param {Array<Item|GC>} structs
+ * @param {number} clock
+ * @return {number}
+ *
+ * @private
+ * @function
+ */
+export const findIndexSS = (structs, clock) => {
+  let left = 0
+  let right = structs.length - 1
+  let mid = structs[right]
+  let midclock = mid.id.clock
+  if (midclock === clock) {
+    return right
+  }
+  // @todo does it even make sense to pivot the search?
+  // If a good split misses, it might actually increase the time to find the correct item.
+  // Currently, the only advantage is that search with pivoting might find the item on the first try.
+  let midindex = math.floor((clock / (midclock + mid.length - 1)) * right) // pivoting the search
+  while (left <= right) {
+    mid = structs[midindex]
+    midclock = mid.id.clock
+    if (midclock <= clock) {
+      if (clock < midclock + mid.length) {
+        return midindex
+      }
+      left = midindex + 1
+    } else {
+      right = midindex - 1
+    }
+    midindex = math.floor((left + right) / 2)
+  }
+  // Always check state before looking for a struct in StructStore
+  // Therefore the case of not finding a struct is unexpected
+  throw error.unexpectedCase()
+}
+
+/**
+ * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
+ *
+ * @param {StructStore} store
+ * @param {ID} id
+ * @return {GC|Item}
+ *
+ * @private
+ * @function
+ */
+export const find = (store, id) => {
+  /**
+   * @type {Array<GC|Item>}
+   */
+  // @ts-ignore
+  const structs = store.clients.get(id.client)
+  return structs[findIndexSS(structs, id.clock)]
+}
+
+/**
+ * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
+ * @private
+ * @function
+ */
+export const getItem = /** @type {function(StructStore,ID):Item} */ (find)
+
+/**
+ * @param {Transaction} transaction
+ * @param {Array<Item|GC>} structs
+ * @param {number} clock
+ */
+export const findIndexCleanStart = (transaction, structs, clock) => {
+  const index = findIndexSS(structs, clock)
+  const struct = structs[index]
+  if (struct.id.clock < clock && struct instanceof Item) {
+    structs.splice(index + 1, 0, splitItem(transaction, struct, clock - struct.id.clock))
+    return index + 1
+  }
+  return index
+}
+
+/**
+ * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
+ *
+ * @param {Transaction} transaction
+ * @param {ID} id
+ * @return {Item}
+ *
+ * @private
+ * @function
+ */
+export const getItemCleanStart = (transaction, id) => {
+  const structs = /** @type {Array<Item>} */ (transaction.doc.store.clients.get(id.client))
+  return structs[findIndexCleanStart(transaction, structs, id.clock)]
+}
+
+/**
+ * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
+ *
+ * @param {Transaction} transaction
+ * @param {StructStore} store
+ * @param {ID} id
+ * @return {Item}
+ *
+ * @private
+ * @function
+ */
+export const getItemCleanEnd = (transaction, store, id) => {
+  /**
+   * @type {Array<Item>}
+   */
+  // @ts-ignore
+  const structs = store.clients.get(id.client)
+  const index = findIndexSS(structs, id.clock)
+  const struct = structs[index]
+  if (id.clock !== struct.id.clock + struct.length - 1 && struct.constructor !== GC) {
+    structs.splice(index + 1, 0, splitItem(transaction, struct, id.clock - struct.id.clock + 1))
+  }
+  return struct
+}
+
+/**
+ * Replace `item` with `newitem` in store
+ * @param {StructStore} store
+ * @param {GC|Item} struct
+ * @param {GC|Item} newStruct
+ *
+ * @private
+ * @function
+ */
+export const replaceStruct = (store, struct, newStruct) => {
+  const structs = /** @type {Array<GC|Item>} */ (store.clients.get(struct.id.client))
+  structs[findIndexSS(structs, struct.id.clock)] = newStruct
+}
+
+/**
+ * Iterate over a range of structs
+ *
+ * @param {Transaction} transaction
+ * @param {Array<Item|GC>} structs
+ * @param {number} clockStart Inclusive start
+ * @param {number} len
+ * @param {function(GC|Item):void} f
+ *
+ * @function
+ */
+export const iterateStructs = (transaction, structs, clockStart, len, f) => {
+  if (len === 0) {
+    return
+  }
+  const clockEnd = clockStart + len
+  let index = findIndexCleanStart(transaction, structs, clockStart)
+  let struct
+  do {
+    struct = structs[index++]
+    if (clockEnd < struct.id.clock + struct.length) {
+      findIndexCleanStart(transaction, structs, clockEnd)
+    }
+    f(struct)
+  } while (index < structs.length && structs[index].id.clock < clockEnd)
+}

src/utils/Transaction.js

@@ -0,0 +1,413 @@
+
+import {
+  getState,
+  writeStructsFromTransaction,
+  writeDeleteSet,
+  DeleteSet,
+  sortAndMergeDeleteSet,
+  getStateVector,
+  findIndexSS,
+  callEventHandlerListeners,
+  Item,
+  generateNewClientId,
+  createID,
+  UpdateEncoderV1, UpdateEncoderV2, GC, StructStore, AbstractType, AbstractStruct, YEvent, Doc // eslint-disable-line
+} from '../internals.js'
+
+import * as map from 'lib0/map'
+import * as math from 'lib0/math'
+import * as set from 'lib0/set'
+import * as logging from 'lib0/logging'
+import { callAll } from 'lib0/function'
+
+/**
+ * A transaction is created for every change on the Yjs model. It is possible
+ * to bundle changes on the Yjs model in a single transaction to
+ * minimize the number on messages sent and the number of observer calls.
+ * If possible the user of this library should bundle as many changes as
+ * possible. Here is an example to illustrate the advantages of bundling:
+ *
+ * @example
+ * const map = y.define('map', YMap)
+ * // Log content when change is triggered
+ * map.observe(() => {
+ *   console.log('change triggered')
+ * })
+ * // Each change on the map type triggers a log message:
+ * map.set('a', 0) // => "change triggered"
+ * map.set('b', 0) // => "change triggered"
+ * // When put in a transaction, it will trigger the log after the transaction:
+ * y.transact(() => {
+ *   map.set('a', 1)
+ *   map.set('b', 1)
+ * }) // => "change triggered"
+ *
+ * @public
+ */
+export class Transaction {
+  /**
+   * @param {Doc} doc
+   * @param {any} origin
+   * @param {boolean} local
+   */
+  constructor (doc, origin, local) {
+    /**
+     * The Yjs instance.
+     * @type {Doc}
+     */
+    this.doc = doc
+    /**
+     * Describes the set of deleted items by ids
+     * @type {DeleteSet}
+     */
+    this.deleteSet = new DeleteSet()
+    /**
+     * Holds the state before the transaction started.
+     * @type {Map<Number,Number>}
+     */
+    this.beforeState = getStateVector(doc.store)
+    /**
+     * Holds the state after the transaction.
+     * @type {Map<Number,Number>}
+     */
+    this.afterState = new Map()
+    /**
+     * All types that were directly modified (property added or child
+     * inserted/deleted). New types are not included in this Set.
+     * Maps from type to parentSubs (`item.parentSub = null` for YArray)
+     * @type {Map<AbstractType<YEvent>,Set<String|null>>}
+     */
+    this.changed = new Map()
+    /**
+     * Stores the events for the types that observe also child elements.
+     * It is mainly used by `observeDeep`.
+     * @type {Map<AbstractType<YEvent>,Array<YEvent>>}
+     */
+    this.changedParentTypes = new Map()
+    /**
+     * @type {Array<AbstractStruct>}
+     */
+    this._mergeStructs = []
+    /**
+     * @type {any}
+     */
+    this.origin = origin
+    /**
+     * Stores meta information on the transaction
+     * @type {Map<any,any>}
+     */
+    this.meta = new Map()
+    /**
+     * Whether this change originates from this doc.
+     * @type {boolean}
+     */
+    this.local = local
+    /**
+     * @type {Set<Doc>}
+     */
+    this.subdocsAdded = new Set()
+    /**
+     * @type {Set<Doc>}
+     */
+    this.subdocsRemoved = new Set()
+    /**
+     * @type {Set<Doc>}
+     */
+    this.subdocsLoaded = new Set()
+  }
+}
+
+/**
+ * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+ * @param {Transaction} transaction
+ * @return {boolean} Whether data was written.
+ */
+export const writeUpdateMessageFromTransaction = (encoder, transaction) => {
+  if (transaction.deleteSet.clients.size === 0 && !map.any(transaction.afterState, (clock, client) => transaction.beforeState.get(client) !== clock)) {
+    return false
+  }
+  sortAndMergeDeleteSet(transaction.deleteSet)
+  writeStructsFromTransaction(encoder, transaction)
+  writeDeleteSet(encoder, transaction.deleteSet)
+  return true
+}
+
+/**
+ * @param {Transaction} transaction
+ *
+ * @private
+ * @function
+ */
+export const nextID = transaction => {
+  const y = transaction.doc
+  return createID(y.clientID, getState(y.store, y.clientID))
+}
+
+/**
+ * If `type.parent` was added in current transaction, `type` technically
+ * did not change, it was just added and we should not fire events for `type`.
+ *
+ * @param {Transaction} transaction
+ * @param {AbstractType<YEvent>} type
+ * @param {string|null} parentSub
+ */
+export const addChangedTypeToTransaction = (transaction, type, parentSub) => {
+  const item = type._item
+  if (item === null || (item.id.clock < (transaction.beforeState.get(item.id.client) || 0) && !item.deleted)) {
+    map.setIfUndefined(transaction.changed, type, set.create).add(parentSub)
+  }
+}
+
+/**
+ * @param {Array<AbstractStruct>} structs
+ * @param {number} pos
+ */
+const tryToMergeWithLeft = (structs, pos) => {
+  const left = structs[pos - 1]
+  const right = structs[pos]
+  if (left.deleted === right.deleted && left.constructor === right.constructor) {
+    if (left.mergeWith(right)) {
+      structs.splice(pos, 1)
+      if (right instanceof Item && right.parentSub !== null && /** @type {AbstractType<any>} */ (right.parent)._map.get(right.parentSub) === right) {
+        /** @type {AbstractType<any>} */ (right.parent)._map.set(right.parentSub, /** @type {Item} */ (left))
+      }
+    }
+  }
+}
+
+/**
+ * @param {DeleteSet} ds
+ * @param {StructStore} store
+ * @param {function(Item):boolean} gcFilter
+ */
+const tryGcDeleteSet = (ds, store, gcFilter) => {
+  for (const [client, deleteItems] of ds.clients.entries()) {
+    const structs = /** @type {Array<GC|Item>} */ (store.clients.get(client))
+    for (let di = deleteItems.length - 1; di >= 0; di--) {
+      const deleteItem = deleteItems[di]
+      const endDeleteItemClock = deleteItem.clock + deleteItem.len
+      for (
+        let si = findIndexSS(structs, deleteItem.clock), struct = structs[si];
+        si < structs.length && struct.id.clock < endDeleteItemClock;
+        struct = structs[++si]
+      ) {
+        const struct = structs[si]
+        if (deleteItem.clock + deleteItem.len <= struct.id.clock) {
+          break
+        }
+        if (struct instanceof Item && struct.deleted && !struct.keep && gcFilter(struct)) {
+          struct.gc(store, false)
+        }
+      }
+    }
+  }
+}
+
+/**
+ * @param {DeleteSet} ds
+ * @param {StructStore} store
+ */
+const tryMergeDeleteSet = (ds, store) => {
+  // try to merge deleted / gc'd items
+  // merge from right to left for better efficiecy and so we don't miss any merge targets
+  ds.clients.forEach((deleteItems, client) => {
+    const structs = /** @type {Array<GC|Item>} */ (store.clients.get(client))
+    for (let di = deleteItems.length - 1; di >= 0; di--) {
+      const deleteItem = deleteItems[di]
+      // start with merging the item next to the last deleted item
+      const mostRightIndexToCheck = math.min(structs.length - 1, 1 + findIndexSS(structs, deleteItem.clock + deleteItem.len - 1))
+      for (
+        let si = mostRightIndexToCheck, struct = structs[si];
+        si > 0 && struct.id.clock >= deleteItem.clock;
+        struct = structs[--si]
+      ) {
+        tryToMergeWithLeft(structs, si)
+      }
+    }
+  })
+}
+
+/**
+ * @param {DeleteSet} ds
+ * @param {StructStore} store
+ * @param {function(Item):boolean} gcFilter
+ */
+export const tryGc = (ds, store, gcFilter) => {
+  tryGcDeleteSet(ds, store, gcFilter)
+  tryMergeDeleteSet(ds, store)
+}
+
+/**
+ * @param {Array<Transaction>} transactionCleanups
+ * @param {number} i
+ */
+const cleanupTransactions = (transactionCleanups, i) => {
+  if (i < transactionCleanups.length) {
+    const transaction = transactionCleanups[i]
+    const doc = transaction.doc
+    const store = doc.store
+    const ds = transaction.deleteSet
+    const mergeStructs = transaction._mergeStructs
+    try {
+      sortAndMergeDeleteSet(ds)
+      transaction.afterState = getStateVector(transaction.doc.store)
+      doc._transaction = null
+      doc.emit('beforeObserverCalls', [transaction, doc])
+      /**
+       * An array of event callbacks.
+       *
+       * Each callback is called even if the other ones throw errors.
+       *
+       * @type {Array<function():void>}
+       */
+      const fs = []
+      // observe events on changed types
+      transaction.changed.forEach((subs, itemtype) =>
+        fs.push(() => {
+          if (itemtype._item === null || !itemtype._item.deleted) {
+            itemtype._callObserver(transaction, subs)
+          }
+        })
+      )
+      fs.push(() => {
+        // deep observe events
+        transaction.changedParentTypes.forEach((events, type) =>
+          fs.push(() => {
+            // We need to think about the possibility that the user transforms the
+            // Y.Doc in the event.
+            if (type._item === null || !type._item.deleted) {
+              events = events
+                .filter(event =>
+                  event.target._item === null || !event.target._item.deleted
+                )
+              events
+                .forEach(event => {
+                  event.currentTarget = type
+                })
+              // sort events by path length so that top-level events are fired first.
+              events
+                .sort((event1, event2) => event1.path.length - event2.path.length)
+              // We don't need to check for events.length
+              // because we know it has at least one element
+              callEventHandlerListeners(type._dEH, events, transaction)
+            }
+          })
+        )
+        fs.push(() => doc.emit('afterTransaction', [transaction, doc]))
+      })
+      callAll(fs, [])
+    } finally {
+      // Replace deleted items with ItemDeleted / GC.
+      // This is where content is actually remove from the Yjs Doc.
+      if (doc.gc) {
+        tryGcDeleteSet(ds, store, doc.gcFilter)
+      }
+      tryMergeDeleteSet(ds, store)
+
+      // on all affected store.clients props, try to merge
+      transaction.afterState.forEach((clock, client) => {
+        const beforeClock = transaction.beforeState.get(client) || 0
+        if (beforeClock !== clock) {
+          const structs = /** @type {Array<GC|Item>} */ (store.clients.get(client))
+          // we iterate from right to left so we can safely remove entries
+          const firstChangePos = math.max(findIndexSS(structs, beforeClock), 1)
+          for (let i = structs.length - 1; i >= firstChangePos; i--) {
+            tryToMergeWithLeft(structs, i)
+          }
+        }
+      })
+      // try to merge mergeStructs
+      // @todo: it makes more sense to transform mergeStructs to a DS, sort it, and merge from right to left
+      //        but at the moment DS does not handle duplicates
+      for (let i = 0; i < mergeStructs.length; i++) {
+        const { client, clock } = mergeStructs[i].id
+        const structs = /** @type {Array<GC|Item>} */ (store.clients.get(client))
+        const replacedStructPos = findIndexSS(structs, clock)
+        if (replacedStructPos + 1 < structs.length) {
+          tryToMergeWithLeft(structs, replacedStructPos + 1)
+        }
+        if (replacedStructPos > 0) {
+          tryToMergeWithLeft(structs, replacedStructPos)
+        }
+      }
+      if (!transaction.local && transaction.afterState.get(doc.clientID) !== transaction.beforeState.get(doc.clientID)) {
+        doc.clientID = generateNewClientId()
+        logging.print(logging.ORANGE, logging.BOLD, '[yjs] ', logging.UNBOLD, logging.RED, 'Changed the client-id because another client seems to be using it.')
+      }
+      // @todo Merge all the transactions into one and provide send the data as a single update message
+      doc.emit('afterTransactionCleanup', [transaction, doc])
+      if (doc._observers.has('update')) {
+        const encoder = new UpdateEncoderV1()
+        const hasContent = writeUpdateMessageFromTransaction(encoder, transaction)
+        if (hasContent) {
+          doc.emit('update', [encoder.toUint8Array(), transaction.origin, doc, transaction])
+        }
+      }
+      if (doc._observers.has('updateV2')) {
+        const encoder = new UpdateEncoderV2()
+        const hasContent = writeUpdateMessageFromTransaction(encoder, transaction)
+        if (hasContent) {
+          doc.emit('updateV2', [encoder.toUint8Array(), transaction.origin, doc, transaction])
+        }
+      }
+      const { subdocsAdded, subdocsLoaded, subdocsRemoved } = transaction
+      if (subdocsAdded.size > 0 || subdocsRemoved.size > 0 || subdocsLoaded.size > 0) {
+        subdocsAdded.forEach(subdoc => {
+          subdoc.clientID = doc.clientID
+          if (subdoc.collectionid == null) {
+            subdoc.collectionid = doc.collectionid
+          }
+          doc.subdocs.add(subdoc)
+        })
+        subdocsRemoved.forEach(subdoc => doc.subdocs.delete(subdoc))
+        doc.emit('subdocs', [{ loaded: subdocsLoaded, added: subdocsAdded, removed: subdocsRemoved }, doc, transaction])
+        subdocsRemoved.forEach(subdoc => subdoc.destroy())
+      }
+
+      if (transactionCleanups.length <= i + 1) {
+        doc._transactionCleanups = []
+        doc.emit('afterAllTransactions', [doc, transactionCleanups])
+      } else {
+        cleanupTransactions(transactionCleanups, i + 1)
+      }
+    }
+  }
+}
+
+/**
+ * Implements the functionality of `y.transact(()=>{..})`
+ *
+ * @param {Doc} doc
+ * @param {function(Transaction):void} f
+ * @param {any} [origin=true]
+ *
+ * @function
+ */
+export const transact = (doc, f, origin = null, local = true) => {
+  const transactionCleanups = doc._transactionCleanups
+  let initialCall = false
+  if (doc._transaction === null) {
+    initialCall = true
+    doc._transaction = new Transaction(doc, origin, local)
+    transactionCleanups.push(doc._transaction)
+    if (transactionCleanups.length === 1) {
+      doc.emit('beforeAllTransactions', [doc])
+    }
+    doc.emit('beforeTransaction', [doc._transaction, doc])
+  }
+  try {
+    f(doc._transaction)
+  } finally {
+    if (initialCall && transactionCleanups[0] === doc._transaction) {
+      // The first transaction ended, now process observer calls.
+      // Observer call may create new transactions for which we need to call the observers and do cleanup.
+      // We don't want to nest these calls, so we execute these calls one after
+      // another.
+      // Also we need to ensure that all cleanups are called, even if the
+      // observes throw errors.
+      // This file is full of hacky try {} finally {} blocks to ensure that an
+      // event can throw errors and also that the cleanup is called.
+      cleanupTransactions(transactionCleanups, 0)
+    }
+  }
+}

src/utils/UndoManager.js

@@ -0,0 +1,285 @@
+import {
+  mergeDeleteSets,
+  iterateDeletedStructs,
+  keepItem,
+  transact,
+  createID,
+  redoItem,
+  isParentOf,
+  followRedone,
+  getItemCleanStart,
+  isDeleted,
+  addToDeleteSet,
+  Transaction, Doc, Item, GC, DeleteSet, AbstractType, YEvent // eslint-disable-line
+} from '../internals.js'
+
+import * as time from 'lib0/time'
+import { Observable } from 'lib0/observable'
+
+class StackItem {
+  /**
+   * @param {DeleteSet} deletions
+   * @param {DeleteSet} insertions
+   */
+  constructor (deletions, insertions) {
+    this.insertions = insertions
+    this.deletions = deletions
+    /**
+     * Use this to save and restore metadata like selection range
+     */
+    this.meta = new Map()
+  }
+}
+
+/**
+ * @param {UndoManager} undoManager
+ * @param {Array<StackItem>} stack
+ * @param {string} eventType
+ * @return {StackItem?}
+ */
+const popStackItem = (undoManager, stack, eventType) => {
+  /**
+   * Whether a change happened
+   * @type {StackItem?}
+   */
+  let result = null
+  /**
+   * Keep a reference to the transaction so we can fire the event with the changedParentTypes
+   * @type {any}
+   */
+  let _tr = null
+  const doc = undoManager.doc
+  const scope = undoManager.scope
+  transact(doc, transaction => {
+    while (stack.length > 0 && result === null) {
+      const store = doc.store
+      const stackItem = /** @type {StackItem} */ (stack.pop())
+      /**
+       * @type {Set<Item>}
+       */
+      const itemsToRedo = new Set()
+      /**
+       * @type {Array<Item>}
+       */
+      const itemsToDelete = []
+      let performedChange = false
+      iterateDeletedStructs(transaction, stackItem.insertions, struct => {
+        if (struct instanceof Item) {
+          if (struct.redone !== null) {
+            let { item, diff } = followRedone(store, struct.id)
+            if (diff > 0) {
+              item = getItemCleanStart(transaction, createID(item.id.client, item.id.clock + diff))
+            }
+            struct = item
+          }
+          if (!struct.deleted && scope.some(type => isParentOf(type, /** @type {Item} */ (struct)))) {
+            itemsToDelete.push(struct)
+          }
+        }
+      })
+      iterateDeletedStructs(transaction, stackItem.deletions, struct => {
+        if (
+          struct instanceof Item &&
+          scope.some(type => isParentOf(type, struct)) &&
+          // Never redo structs in stackItem.insertions because they were created and deleted in the same capture interval.
+          !isDeleted(stackItem.insertions, struct.id)
+        ) {
+          itemsToRedo.add(struct)
+        }
+      })
+      itemsToRedo.forEach(struct => {
+        performedChange = redoItem(transaction, struct, itemsToRedo, itemsToDelete) !== null || performedChange
+      })
+      // We want to delete in reverse order so that children are deleted before
+      // parents, so we have more information available when items are filtered.
+      for (let i = itemsToDelete.length - 1; i >= 0; i--) {
+        const item = itemsToDelete[i]
+        if (undoManager.deleteFilter(item)) {
+          item.delete(transaction)
+          performedChange = true
+        }
+      }
+      result = performedChange ? stackItem : null
+    }
+    transaction.changed.forEach((subProps, type) => {
+      // destroy search marker if necessary
+      if (subProps.has(null) && type._searchMarker) {
+        type._searchMarker.length = 0
+      }
+    })
+    _tr = transaction
+  }, undoManager)
+  if (result != null) {
+    const changedParentTypes = _tr.changedParentTypes
+    undoManager.emit('stack-item-popped', [{ stackItem: result, type: eventType, changedParentTypes }, undoManager])
+  }
+  return result
+}
+
+/**
+ * @typedef {Object} UndoManagerOptions
+ * @property {number} [UndoManagerOptions.captureTimeout=500]
+ * @property {function(Item):boolean} [UndoManagerOptions.deleteFilter=()=>true] Sometimes
+ * it is necessary to filter whan an Undo/Redo operation can delete. If this
+ * filter returns false, the type/item won't be deleted even it is in the
+ * undo/redo scope.
+ * @property {Set<any>} [UndoManagerOptions.trackedOrigins=new Set([null])]
+ */
+
+/**
+ * Fires 'stack-item-added' event when a stack item was added to either the undo- or
+ * the redo-stack. You may store additional stack information via the
+ * metadata property on `event.stackItem.meta` (it is a `Map` of metadata properties).
+ * Fires 'stack-item-popped' event when a stack item was popped from either the
+ * undo- or the redo-stack. You may restore the saved stack information from `event.stackItem.meta`.
+ *
+ * @extends {Observable<'stack-item-added'|'stack-item-popped'>}
+ */
+export class UndoManager extends Observable {
+  /**
+   * @param {AbstractType<any>|Array<AbstractType<any>>} typeScope Accepts either a single type, or an array of types
+   * @param {UndoManagerOptions} options
+   */
+  constructor (typeScope, { captureTimeout = 500, deleteFilter = () => true, trackedOrigins = new Set([null]) } = {}) {
+    super()
+    this.scope = typeScope instanceof Array ? typeScope : [typeScope]
+    this.deleteFilter = deleteFilter
+    trackedOrigins.add(this)
+    this.trackedOrigins = trackedOrigins
+    /**
+     * @type {Array<StackItem>}
+     */
+    this.undoStack = []
+    /**
+     * @type {Array<StackItem>}
+     */
+    this.redoStack = []
+    /**
+     * Whether the client is currently undoing (calling UndoManager.undo)
+     *
+     * @type {boolean}
+     */
+    this.undoing = false
+    this.redoing = false
+    this.doc = /** @type {Doc} */ (this.scope[0].doc)
+    this.lastChange = 0
+    this.doc.on('afterTransaction', /** @param {Transaction} transaction */ transaction => {
+      // Only track certain transactions
+      if (!this.scope.some(type => transaction.changedParentTypes.has(type)) || (!this.trackedOrigins.has(transaction.origin) && (!transaction.origin || !this.trackedOrigins.has(transaction.origin.constructor)))) {
+        return
+      }
+      const undoing = this.undoing
+      const redoing = this.redoing
+      const stack = undoing ? this.redoStack : this.undoStack
+      if (undoing) {
+        this.stopCapturing() // next undo should not be appended to last stack item
+      } else if (!redoing) {
+        // neither undoing nor redoing: delete redoStack
+        this.redoStack = []
+      }
+      const insertions = new DeleteSet()
+      transaction.afterState.forEach((endClock, client) => {
+        const startClock = transaction.beforeState.get(client) || 0
+        const len = endClock - startClock
+        if (len > 0) {
+          addToDeleteSet(insertions, client, startClock, len)
+        }
+      })
+      const now = time.getUnixTime()
+      if (now - this.lastChange < captureTimeout && stack.length > 0 && !undoing && !redoing) {
+        // append change to last stack op
+        const lastOp = stack[stack.length - 1]
+        lastOp.deletions = mergeDeleteSets([lastOp.deletions, transaction.deleteSet])
+        lastOp.insertions = mergeDeleteSets([lastOp.insertions, insertions])
+      } else {
+        // create a new stack op
+        stack.push(new StackItem(transaction.deleteSet, insertions))
+      }
+      if (!undoing && !redoing) {
+        this.lastChange = now
+      }
+      // make sure that deleted structs are not gc'd
+      iterateDeletedStructs(transaction, transaction.deleteSet, /** @param {Item|GC} item */ item => {
+        if (item instanceof Item && this.scope.some(type => isParentOf(type, item))) {
+          keepItem(item, true)
+        }
+      })
+      this.emit('stack-item-added', [{ stackItem: stack[stack.length - 1], origin: transaction.origin, type: undoing ? 'redo' : 'undo', changedParentTypes: transaction.changedParentTypes }, this])
+    })
+  }
+
+  clear () {
+    this.doc.transact(transaction => {
+      /**
+       * @param {StackItem} stackItem
+       */
+      const clearItem = stackItem => {
+        iterateDeletedStructs(transaction, stackItem.deletions, item => {
+          if (item instanceof Item && this.scope.some(type => isParentOf(type, item))) {
+            keepItem(item, false)
+          }
+        })
+      }
+      this.undoStack.forEach(clearItem)
+      this.redoStack.forEach(clearItem)
+    })
+    this.undoStack = []
+    this.redoStack = []
+  }
+
+  /**
+   * UndoManager merges Undo-StackItem if they are created within time-gap
+   * smaller than `options.captureTimeout`. Call `um.stopCapturing()` so that the next
+   * StackItem won't be merged.
+   *
+   *
+   * @example
+   *     // without stopCapturing
+   *     ytext.insert(0, 'a')
+   *     ytext.insert(1, 'b')
+   *     um.undo()
+   *     ytext.toString() // => '' (note that 'ab' was removed)
+   *     // with stopCapturing
+   *     ytext.insert(0, 'a')
+   *     um.stopCapturing()
+   *     ytext.insert(0, 'b')
+   *     um.undo()
+   *     ytext.toString() // => 'a' (note that only 'b' was removed)
+   *
+   */
+  stopCapturing () {
+    this.lastChange = 0
+  }
+
+  /**
+   * Undo last changes on type.
+   *
+   * @return {StackItem?} Returns StackItem if a change was applied
+   */
+  undo () {
+    this.undoing = true
+    let res
+    try {
+      res = popStackItem(this, this.undoStack, 'undo')
+    } finally {
+      this.undoing = false
+    }
+    return res
+  }
+
+  /**
+   * Redo last undo operation.
+   *
+   * @return {StackItem?} Returns StackItem if a change was applied
+   */
+  redo () {
+    this.redoing = true
+    let res
+    try {
+      res = popStackItem(this, this.redoStack, 'redo')
+    } finally {
+      this.redoing = false
+    }
+    return res
+  }
+}

src/utils/UpdateDecoder.js

@@ -0,0 +1,281 @@
+import * as buffer from 'lib0/buffer'
+import * as decoding from 'lib0/decoding'
+import {
+  ID, createID
+} from '../internals.js'
+
+export class DSDecoderV1 {
+  /**
+   * @param {decoding.Decoder} decoder
+   */
+  constructor (decoder) {
+    this.restDecoder = decoder
+  }
+
+  resetDsCurVal () {
+    // nop
+  }
+
+  /**
+   * @return {number}
+   */
+  readDsClock () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * @return {number}
+   */
+  readDsLen () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+}
+
+export class UpdateDecoderV1 extends DSDecoderV1 {
+  /**
+   * @return {ID}
+   */
+  readLeftID () {
+    return createID(decoding.readVarUint(this.restDecoder), decoding.readVarUint(this.restDecoder))
+  }
+
+  /**
+   * @return {ID}
+   */
+  readRightID () {
+    return createID(decoding.readVarUint(this.restDecoder), decoding.readVarUint(this.restDecoder))
+  }
+
+  /**
+   * Read the next client id.
+   * Use this in favor of readID whenever possible to reduce the number of objects created.
+   */
+  readClient () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readInfo () {
+    return decoding.readUint8(this.restDecoder)
+  }
+
+  /**
+   * @return {string}
+   */
+  readString () {
+    return decoding.readVarString(this.restDecoder)
+  }
+
+  /**
+   * @return {boolean} isKey
+   */
+  readParentInfo () {
+    return decoding.readVarUint(this.restDecoder) === 1
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readTypeRef () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @return {number} len
+   */
+  readLen () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * @return {any}
+   */
+  readAny () {
+    return decoding.readAny(this.restDecoder)
+  }
+
+  /**
+   * @return {Uint8Array}
+   */
+  readBuf () {
+    return buffer.copyUint8Array(decoding.readVarUint8Array(this.restDecoder))
+  }
+
+  /**
+   * Legacy implementation uses JSON parse. We use any-decoding in v2.
+   *
+   * @return {any}
+   */
+  readJSON () {
+    return JSON.parse(decoding.readVarString(this.restDecoder))
+  }
+
+  /**
+   * @return {string}
+   */
+  readKey () {
+    return decoding.readVarString(this.restDecoder)
+  }
+}
+
+export class DSDecoderV2 {
+  /**
+   * @param {decoding.Decoder} decoder
+   */
+  constructor (decoder) {
+    /**
+     * @private
+     */
+    this.dsCurrVal = 0
+    this.restDecoder = decoder
+  }
+
+  resetDsCurVal () {
+    this.dsCurrVal = 0
+  }
+
+  /**
+   * @return {number}
+   */
+  readDsClock () {
+    this.dsCurrVal += decoding.readVarUint(this.restDecoder)
+    return this.dsCurrVal
+  }
+
+  /**
+   * @return {number}
+   */
+  readDsLen () {
+    const diff = decoding.readVarUint(this.restDecoder) + 1
+    this.dsCurrVal += diff
+    return diff
+  }
+}
+
+export class UpdateDecoderV2 extends DSDecoderV2 {
+  /**
+   * @param {decoding.Decoder} decoder
+   */
+  constructor (decoder) {
+    super(decoder)
+    /**
+     * List of cached keys. If the keys[id] does not exist, we read a new key
+     * from stringEncoder and push it to keys.
+     *
+     * @type {Array<string>}
+     */
+    this.keys = []
+    decoding.readVarUint(decoder) // read feature flag - currently unused
+    this.keyClockDecoder = new decoding.IntDiffOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.clientDecoder = new decoding.UintOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.leftClockDecoder = new decoding.IntDiffOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.rightClockDecoder = new decoding.IntDiffOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.infoDecoder = new decoding.RleDecoder(decoding.readVarUint8Array(decoder), decoding.readUint8)
+    this.stringDecoder = new decoding.StringDecoder(decoding.readVarUint8Array(decoder))
+    this.parentInfoDecoder = new decoding.RleDecoder(decoding.readVarUint8Array(decoder), decoding.readUint8)
+    this.typeRefDecoder = new decoding.UintOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.lenDecoder = new decoding.UintOptRleDecoder(decoding.readVarUint8Array(decoder))
+  }
+
+  /**
+   * @return {ID}
+   */
+  readLeftID () {
+    return new ID(this.clientDecoder.read(), this.leftClockDecoder.read())
+  }
+
+  /**
+   * @return {ID}
+   */
+  readRightID () {
+    return new ID(this.clientDecoder.read(), this.rightClockDecoder.read())
+  }
+
+  /**
+   * Read the next client id.
+   * Use this in favor of readID whenever possible to reduce the number of objects created.
+   */
+  readClient () {
+    return this.clientDecoder.read()
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readInfo () {
+    return /** @type {number} */ (this.infoDecoder.read())
+  }
+
+  /**
+   * @return {string}
+   */
+  readString () {
+    return this.stringDecoder.read()
+  }
+
+  /**
+   * @return {boolean}
+   */
+  readParentInfo () {
+    return this.parentInfoDecoder.read() === 1
+  }
+
+  /**
+   * @return {number} An unsigned 8-bit integer
+   */
+  readTypeRef () {
+    return this.typeRefDecoder.read()
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @return {number}
+   */
+  readLen () {
+    return this.lenDecoder.read()
+  }
+
+  /**
+   * @return {any}
+   */
+  readAny () {
+    return decoding.readAny(this.restDecoder)
+  }
+
+  /**
+   * @return {Uint8Array}
+   */
+  readBuf () {
+    return decoding.readVarUint8Array(this.restDecoder)
+  }
+
+  /**
+   * This is mainly here for legacy purposes.
+   *
+   * Initial we incoded objects using JSON. Now we use the much faster lib0/any-encoder. This method mainly exists for legacy purposes for the v1 encoder.
+   *
+   * @return {any}
+   */
+  readJSON () {
+    return decoding.readAny(this.restDecoder)
+  }
+
+  /**
+   * @return {string}
+   */
+  readKey () {
+    const keyClock = this.keyClockDecoder.read()
+    if (keyClock < this.keys.length) {
+      return this.keys[keyClock]
+    } else {
+      const key = this.stringDecoder.read()
+      this.keys.push(key)
+      return key
+    }
+  }
+}

src/utils/UpdateEncoder.js

@@ -0,0 +1,307 @@
+
+import * as error from 'lib0/error'
+import * as encoding from 'lib0/encoding'
+
+import {
+  ID // eslint-disable-line
+} from '../internals.js'
+
+export class DSEncoderV1 {
+  constructor () {
+    this.restEncoder = encoding.createEncoder()
+  }
+
+  toUint8Array () {
+    return encoding.toUint8Array(this.restEncoder)
+  }
+
+  resetDsCurVal () {
+    // nop
+  }
+
+  /**
+   * @param {number} clock
+   */
+  writeDsClock (clock) {
+    encoding.writeVarUint(this.restEncoder, clock)
+  }
+
+  /**
+   * @param {number} len
+   */
+  writeDsLen (len) {
+    encoding.writeVarUint(this.restEncoder, len)
+  }
+}
+
+export class UpdateEncoderV1 extends DSEncoderV1 {
+  /**
+   * @param {ID} id
+   */
+  writeLeftID (id) {
+    encoding.writeVarUint(this.restEncoder, id.client)
+    encoding.writeVarUint(this.restEncoder, id.clock)
+  }
+
+  /**
+   * @param {ID} id
+   */
+  writeRightID (id) {
+    encoding.writeVarUint(this.restEncoder, id.client)
+    encoding.writeVarUint(this.restEncoder, id.clock)
+  }
+
+  /**
+   * Use writeClient and writeClock instead of writeID if possible.
+   * @param {number} client
+   */
+  writeClient (client) {
+    encoding.writeVarUint(this.restEncoder, client)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeInfo (info) {
+    encoding.writeUint8(this.restEncoder, info)
+  }
+
+  /**
+   * @param {string} s
+   */
+  writeString (s) {
+    encoding.writeVarString(this.restEncoder, s)
+  }
+
+  /**
+   * @param {boolean} isYKey
+   */
+  writeParentInfo (isYKey) {
+    encoding.writeVarUint(this.restEncoder, isYKey ? 1 : 0)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeTypeRef (info) {
+    encoding.writeVarUint(this.restEncoder, info)
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @param {number} len
+   */
+  writeLen (len) {
+    encoding.writeVarUint(this.restEncoder, len)
+  }
+
+  /**
+   * @param {any} any
+   */
+  writeAny (any) {
+    encoding.writeAny(this.restEncoder, any)
+  }
+
+  /**
+   * @param {Uint8Array} buf
+   */
+  writeBuf (buf) {
+    encoding.writeVarUint8Array(this.restEncoder, buf)
+  }
+
+  /**
+   * @param {any} embed
+   */
+  writeJSON (embed) {
+    encoding.writeVarString(this.restEncoder, JSON.stringify(embed))
+  }
+
+  /**
+   * @param {string} key
+   */
+  writeKey (key) {
+    encoding.writeVarString(this.restEncoder, key)
+  }
+}
+
+export class DSEncoderV2 {
+  constructor () {
+    this.restEncoder = encoding.createEncoder() // encodes all the rest / non-optimized
+    this.dsCurrVal = 0
+  }
+
+  toUint8Array () {
+    return encoding.toUint8Array(this.restEncoder)
+  }
+
+  resetDsCurVal () {
+    this.dsCurrVal = 0
+  }
+
+  /**
+   * @param {number} clock
+   */
+  writeDsClock (clock) {
+    const diff = clock - this.dsCurrVal
+    this.dsCurrVal = clock
+    encoding.writeVarUint(this.restEncoder, diff)
+  }
+
+  /**
+   * @param {number} len
+   */
+  writeDsLen (len) {
+    if (len === 0) {
+      error.unexpectedCase()
+    }
+    encoding.writeVarUint(this.restEncoder, len - 1)
+    this.dsCurrVal += len
+  }
+}
+
+export class UpdateEncoderV2 extends DSEncoderV2 {
+  constructor () {
+    super()
+    /**
+     * @type {Map<string,number>}
+     */
+    this.keyMap = new Map()
+    /**
+     * Refers to the next uniqe key-identifier to me used.
+     * See writeKey method for more information.
+     *
+     * @type {number}
+     */
+    this.keyClock = 0
+    this.keyClockEncoder = new encoding.IntDiffOptRleEncoder()
+    this.clientEncoder = new encoding.UintOptRleEncoder()
+    this.leftClockEncoder = new encoding.IntDiffOptRleEncoder()
+    this.rightClockEncoder = new encoding.IntDiffOptRleEncoder()
+    this.infoEncoder = new encoding.RleEncoder(encoding.writeUint8)
+    this.stringEncoder = new encoding.StringEncoder()
+    this.parentInfoEncoder = new encoding.RleEncoder(encoding.writeUint8)
+    this.typeRefEncoder = new encoding.UintOptRleEncoder()
+    this.lenEncoder = new encoding.UintOptRleEncoder()
+  }
+
+  toUint8Array () {
+    const encoder = encoding.createEncoder()
+    encoding.writeVarUint(encoder, 0) // this is a feature flag that we might use in the future
+    encoding.writeVarUint8Array(encoder, this.keyClockEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.clientEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.leftClockEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.rightClockEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, encoding.toUint8Array(this.infoEncoder))
+    encoding.writeVarUint8Array(encoder, this.stringEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, encoding.toUint8Array(this.parentInfoEncoder))
+    encoding.writeVarUint8Array(encoder, this.typeRefEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.lenEncoder.toUint8Array())
+    // @note The rest encoder is appended! (note the missing var)
+    encoding.writeUint8Array(encoder, encoding.toUint8Array(this.restEncoder))
+    return encoding.toUint8Array(encoder)
+  }
+
+  /**
+   * @param {ID} id
+   */
+  writeLeftID (id) {
+    this.clientEncoder.write(id.client)
+    this.leftClockEncoder.write(id.clock)
+  }
+
+  /**
+   * @param {ID} id
+   */
+  writeRightID (id) {
+    this.clientEncoder.write(id.client)
+    this.rightClockEncoder.write(id.clock)
+  }
+
+  /**
+   * @param {number} client
+   */
+  writeClient (client) {
+    this.clientEncoder.write(client)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeInfo (info) {
+    this.infoEncoder.write(info)
+  }
+
+  /**
+   * @param {string} s
+   */
+  writeString (s) {
+    this.stringEncoder.write(s)
+  }
+
+  /**
+   * @param {boolean} isYKey
+   */
+  writeParentInfo (isYKey) {
+    this.parentInfoEncoder.write(isYKey ? 1 : 0)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeTypeRef (info) {
+    this.typeRefEncoder.write(info)
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @param {number} len
+   */
+  writeLen (len) {
+    this.lenEncoder.write(len)
+  }
+
+  /**
+   * @param {any} any
+   */
+  writeAny (any) {
+    encoding.writeAny(this.restEncoder, any)
+  }
+
+  /**
+   * @param {Uint8Array} buf
+   */
+  writeBuf (buf) {
+    encoding.writeVarUint8Array(this.restEncoder, buf)
+  }
+
+  /**
+   * This is mainly here for legacy purposes.
+   *
+   * Initial we incoded objects using JSON. Now we use the much faster lib0/any-encoder. This method mainly exists for legacy purposes for the v1 encoder.
+   *
+   * @param {any} embed
+   */
+  writeJSON (embed) {
+    encoding.writeAny(this.restEncoder, embed)
+  }
+
+  /**
+   * Property keys are often reused. For example, in y-prosemirror the key `bold` might
+   * occur very often. For a 3d application, the key `position` might occur very often.
+   *
+   * We cache these keys in a Map and refer to them via a unique number.
+   *
+   * @param {string} key
+   */
+  writeKey (key) {
+    const clock = this.keyMap.get(key)
+    if (clock === undefined) {
+      this.keyClockEncoder.write(this.keyClock++)
+      this.stringEncoder.write(key)
+    } else {
+      this.keyClockEncoder.write(this.keyClock++)
+    }
+  }
+}

src/utils/YEvent.js

@@ -0,0 +1,255 @@
+
+import {
+  isDeleted,
+  Item, AbstractType, Transaction, AbstractStruct // eslint-disable-line
+} from '../internals.js'
+
+import * as set from 'lib0/set'
+import * as array from 'lib0/array'
+
+/**
+ * YEvent describes the changes on a YType.
+ */
+export class YEvent {
+  /**
+   * @param {AbstractType<any>} target The changed type.
+   * @param {Transaction} transaction
+   */
+  constructor (target, transaction) {
+    /**
+     * The type on which this event was created on.
+     * @type {AbstractType<any>}
+     */
+    this.target = target
+    /**
+     * The current target on which the observe callback is called.
+     * @type {AbstractType<any>}
+     */
+    this.currentTarget = target
+    /**
+     * The transaction that triggered this event.
+     * @type {Transaction}
+     */
+    this.transaction = transaction
+    /**
+     * @type {Object|null}
+     */
+    this._changes = null
+    /**
+     * @type {null | Map<string, { action: 'add' | 'update' | 'delete', oldValue: any, newValue: any }>}
+     */
+    this._keys = null
+    /**
+     * @type {null | Array<{ insert?: string | Array<any> | object | AbstractType<any>, retain?: number, delete?: number, attributes?: Object<string, any> }>}
+     */
+    this._delta = null
+  }
+
+  /**
+   * Computes the path from `y` to the changed type.
+   *
+   * @todo v14 should standardize on path: Array<{parent, index}> because that is easier to work with.
+   *
+   * The following property holds:
+   * @example
+   *   let type = y
+   *   event.path.forEach(dir => {
+   *     type = type.get(dir)
+   *   })
+   *   type === event.target // => true
+   */
+  get path () {
+    // @ts-ignore _item is defined because target is integrated
+    return getPathTo(this.currentTarget, this.target)
+  }
+
+  /**
+   * Check if a struct is deleted by this event.
+   *
+   * In contrast to change.deleted, this method also returns true if the struct was added and then deleted.
+   *
+   * @param {AbstractStruct} struct
+   * @return {boolean}
+   */
+  deletes (struct) {
+    return isDeleted(this.transaction.deleteSet, struct.id)
+  }
+
+  /**
+   * @type {Map<string, { action: 'add' | 'update' | 'delete', oldValue: any, newValue: any }>}
+   */
+  get keys () {
+    if (this._keys === null) {
+      const keys = new Map()
+      const target = this.target
+      const changed = /** @type Set<string|null> */ (this.transaction.changed.get(target))
+      changed.forEach(key => {
+        if (key !== null) {
+          const item = /** @type {Item} */ (target._map.get(key))
+          /**
+           * @type {'delete' | 'add' | 'update'}
+           */
+          let action
+          let oldValue
+          if (this.adds(item)) {
+            let prev = item.left
+            while (prev !== null && this.adds(prev)) {
+              prev = prev.left
+            }
+            if (this.deletes(item)) {
+              if (prev !== null && this.deletes(prev)) {
+                action = 'delete'
+                oldValue = array.last(prev.content.getContent())
+              } else {
+                return
+              }
+            } else {
+              if (prev !== null && this.deletes(prev)) {
+                action = 'update'
+                oldValue = array.last(prev.content.getContent())
+              } else {
+                action = 'add'
+                oldValue = undefined
+              }
+            }
+          } else {
+            if (this.deletes(item)) {
+              action = 'delete'
+              oldValue = array.last(/** @type {Item} */ item.content.getContent())
+            } else {
+              return // nop
+            }
+          }
+          keys.set(key, { action, oldValue })
+        }
+      })
+      this._keys = keys
+    }
+    return this._keys
+  }
+
+  /**
+   * @type {Array<{insert?: string | Array<any> | object | AbstractType<any>, retain?: number, delete?: number, attributes?: Object<string, any>}>}
+   */
+  get delta () {
+    return this.changes.delta
+  }
+
+  /**
+   * Check if a struct is added by this event.
+   *
+   * In contrast to change.deleted, this method also returns true if the struct was added and then deleted.
+   *
+   * @param {AbstractStruct} struct
+   * @return {boolean}
+   */
+  adds (struct) {
+    return struct.id.clock >= (this.transaction.beforeState.get(struct.id.client) || 0)
+  }
+
+  /**
+   * @type {{added:Set<Item>,deleted:Set<Item>,keys:Map<string,{action:'add'|'update'|'delete',oldValue:any}>,delta:Array<{insert?:Array<any>|string, delete?:number, retain?:number}>}}
+   */
+  get changes () {
+    let changes = this._changes
+    if (changes === null) {
+      const target = this.target
+      const added = set.create()
+      const deleted = set.create()
+      /**
+       * @type {Array<{insert:Array<any>}|{delete:number}|{retain:number}>}
+       */
+      const delta = []
+      changes = {
+        added,
+        deleted,
+        delta,
+        keys: this.keys
+      }
+      const changed = /** @type Set<string|null> */ (this.transaction.changed.get(target))
+      if (changed.has(null)) {
+        /**
+         * @type {any}
+         */
+        let lastOp = null
+        const packOp = () => {
+          if (lastOp) {
+            delta.push(lastOp)
+          }
+        }
+        for (let item = target._start; item !== null; item = item.right) {
+          if (item.deleted) {
+            if (this.deletes(item) && !this.adds(item)) {
+              if (lastOp === null || lastOp.delete === undefined) {
+                packOp()
+                lastOp = { delete: 0 }
+              }
+              lastOp.delete += item.length
+              deleted.add(item)
+            } // else nop
+          } else {
+            if (this.adds(item)) {
+              if (lastOp === null || lastOp.insert === undefined) {
+                packOp()
+                lastOp = { insert: [] }
+              }
+              lastOp.insert = lastOp.insert.concat(item.content.getContent())
+              added.add(item)
+            } else {
+              if (lastOp === null || lastOp.retain === undefined) {
+                packOp()
+                lastOp = { retain: 0 }
+              }
+              lastOp.retain += item.length
+            }
+          }
+        }
+        if (lastOp !== null && lastOp.retain === undefined) {
+          packOp()
+        }
+      }
+      this._changes = changes
+    }
+    return /** @type {any} */ (changes)
+  }
+}
+
+/**
+ * Compute the path from this type to the specified target.
+ *
+ * @example
+ *   // `child` should be accessible via `type.get(path[0]).get(path[1])..`
+ *   const path = type.getPathTo(child)
+ *   // assuming `type instanceof YArray`
+ *   console.log(path) // might look like => [2, 'key1']
+ *   child === type.get(path[0]).get(path[1])
+ *
+ * @param {AbstractType<any>} parent
+ * @param {AbstractType<any>} child target
+ * @return {Array<string|number>} Path to the target
+ *
+ * @private
+ * @function
+ */
+const getPathTo = (parent, child) => {
+  const path = []
+  while (child._item !== null && child !== parent) {
+    if (child._item.parentSub !== null) {
+      // parent is map-ish
+      path.unshift(child._item.parentSub)
+    } else {
+      // parent is array-ish
+      let i = 0
+      let c = /** @type {AbstractType<any>} */ (child._item.parent)._start
+      while (c !== child._item && c !== null) {
+        if (!c.deleted) {
+          i++
+        }
+        c = c.right
+      }
+      path.unshift(i)
+    }
+    child = /** @type {AbstractType<any>} */ (child._item.parent)
+  }
+  return path
+}

src/utils/encoding.js

@@ -0,0 +1,645 @@
+
+/**
+ * @module encoding
+ */
+/*
+ * We use the first five bits in the info flag for determining the type of the struct.
+ *
+ * 0: GC
+ * 1: Item with Deleted content
+ * 2: Item with JSON content
+ * 3: Item with Binary content
+ * 4: Item with String content
+ * 5: Item with Embed content (for richtext content)
+ * 6: Item with Format content (a formatting marker for richtext content)
+ * 7: Item with Type
+ */
+
+import {
+  findIndexSS,
+  getState,
+  createID,
+  getStateVector,
+  readAndApplyDeleteSet,
+  writeDeleteSet,
+  createDeleteSetFromStructStore,
+  transact,
+  readItemContent,
+  UpdateDecoderV1,
+  UpdateDecoderV2,
+  UpdateEncoderV1,
+  UpdateEncoderV2,
+  DSEncoderV2,
+  DSDecoderV1,
+  DSEncoderV1,
+  mergeUpdates,
+  mergeUpdatesV2,
+  Skip,
+  diffUpdateV2,
+  convertUpdateFormatV2ToV1,
+  DSDecoderV2, Doc, Transaction, GC, Item, StructStore // eslint-disable-line
+} from '../internals.js'
+
+import * as encoding from 'lib0/encoding'
+import * as decoding from 'lib0/decoding'
+import * as binary from 'lib0/binary'
+import * as map from 'lib0/map'
+import * as math from 'lib0/math'
+
+/**
+ * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+ * @param {Array<GC|Item>} structs All structs by `client`
+ * @param {number} client
+ * @param {number} clock write structs starting with `ID(client,clock)`
+ *
+ * @function
+ */
+const writeStructs = (encoder, structs, client, clock) => {
+  // write first id
+  clock = math.max(clock, structs[0].id.clock) // make sure the first id exists
+  const startNewStructs = findIndexSS(structs, clock)
+  // write # encoded structs
+  encoding.writeVarUint(encoder.restEncoder, structs.length - startNewStructs)
+  encoder.writeClient(client)
+  encoding.writeVarUint(encoder.restEncoder, clock)
+  const firstStruct = structs[startNewStructs]
+  // write first struct with an offset
+  firstStruct.write(encoder, clock - firstStruct.id.clock)
+  for (let i = startNewStructs + 1; i < structs.length; i++) {
+    structs[i].write(encoder, 0)
+  }
+}
+
+/**
+ * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+ * @param {StructStore} store
+ * @param {Map<number,number>} _sm
+ *
+ * @private
+ * @function
+ */
+export const writeClientsStructs = (encoder, store, _sm) => {
+  // we filter all valid _sm entries into sm
+  const sm = new Map()
+  _sm.forEach((clock, client) => {
+    // only write if new structs are available
+    if (getState(store, client) > clock) {
+      sm.set(client, clock)
+    }
+  })
+  getStateVector(store).forEach((clock, client) => {
+    if (!_sm.has(client)) {
+      sm.set(client, 0)
+    }
+  })
+  // write # states that were updated
+  encoding.writeVarUint(encoder.restEncoder, sm.size)
+  // Write items with higher client ids first
+  // This heavily improves the conflict algorithm.
+  Array.from(sm.entries()).sort((a, b) => b[0] - a[0]).forEach(([client, clock]) => {
+    // @ts-ignore
+    writeStructs(encoder, store.clients.get(client), client, clock)
+  })
+}
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder The decoder object to read data from.
+ * @param {Doc} doc
+ * @return {Map<number, { i: number, refs: Array<Item | GC> }>}
+ *
+ * @private
+ * @function
+ */
+export const readClientsStructRefs = (decoder, doc) => {
+  /**
+   * @type {Map<number, { i: number, refs: Array<Item | GC> }>}
+   */
+  const clientRefs = map.create()
+  const numOfStateUpdates = decoding.readVarUint(decoder.restDecoder)
+  for (let i = 0; i < numOfStateUpdates; i++) {
+    const numberOfStructs = decoding.readVarUint(decoder.restDecoder)
+    /**
+     * @type {Array<GC|Item>}
+     */
+    const refs = new Array(numberOfStructs)
+    const client = decoder.readClient()
+    let clock = decoding.readVarUint(decoder.restDecoder)
+    // const start = performance.now()
+    clientRefs.set(client, { i: 0, refs })
+    for (let i = 0; i < numberOfStructs; i++) {
+      const info = decoder.readInfo()
+      switch (binary.BITS5 & info) {
+        case 0: { // GC
+          const len = decoder.readLen()
+          refs[i] = new GC(createID(client, clock), len)
+          clock += len
+          break
+        }
+        case 10: { // Skip Struct (nothing to apply)
+          // @todo we could reduce the amount of checks by adding Skip struct to clientRefs so we know that something is missing.
+          const len = decoding.readVarUint(decoder.restDecoder)
+          refs[i] = new Skip(createID(client, clock), len)
+          clock += len
+          break
+        }
+        default: { // Item with content
+          /**
+           * The optimized implementation doesn't use any variables because inlining variables is faster.
+           * Below a non-optimized version is shown that implements the basic algorithm with
+           * a few comments
+           */
+          const cantCopyParentInfo = (info & (binary.BIT7 | binary.BIT8)) === 0
+          // If parent = null and neither left nor right are defined, then we know that `parent` is child of `y`
+          // and we read the next string as parentYKey.
+          // It indicates how we store/retrieve parent from `y.share`
+          // @type {string|null}
+          const struct = new Item(
+            createID(client, clock),
+            null, // leftd
+            (info & binary.BIT8) === binary.BIT8 ? decoder.readLeftID() : null, // origin
+            null, // right
+            (info & binary.BIT7) === binary.BIT7 ? decoder.readRightID() : null, // right origin
+            cantCopyParentInfo ? (decoder.readParentInfo() ? doc.get(decoder.readString()) : decoder.readLeftID()) : null, // parent
+            cantCopyParentInfo && (info & binary.BIT6) === binary.BIT6 ? decoder.readString() : null, // parentSub
+            readItemContent(decoder, info) // item content
+          )
+          /* A non-optimized implementation of the above algorithm:
+
+          // The item that was originally to the left of this item.
+          const origin = (info & binary.BIT8) === binary.BIT8 ? decoder.readLeftID() : null
+          // The item that was originally to the right of this item.
+          const rightOrigin = (info & binary.BIT7) === binary.BIT7 ? decoder.readRightID() : null
+          const cantCopyParentInfo = (info & (binary.BIT7 | binary.BIT8)) === 0
+          const hasParentYKey = cantCopyParentInfo ? decoder.readParentInfo() : false
+          // If parent = null and neither left nor right are defined, then we know that `parent` is child of `y`
+          // and we read the next string as parentYKey.
+          // It indicates how we store/retrieve parent from `y.share`
+          // @type {string|null}
+          const parentYKey = cantCopyParentInfo && hasParentYKey ? decoder.readString() : null
+
+          const struct = new Item(
+            createID(client, clock),
+            null, // leftd
+            origin, // origin
+            null, // right
+            rightOrigin, // right origin
+            cantCopyParentInfo && !hasParentYKey ? decoder.readLeftID() : (parentYKey !== null ? doc.get(parentYKey) : null), // parent
+            cantCopyParentInfo && (info & binary.BIT6) === binary.BIT6 ? decoder.readString() : null, // parentSub
+            readItemContent(decoder, info) // item content
+          )
+          */
+          refs[i] = struct
+          clock += struct.length
+        }
+      }
+    }
+    // console.log('time to read: ', performance.now() - start) // @todo remove
+  }
+  return clientRefs
+}
+
+/**
+ * Resume computing structs generated by struct readers.
+ *
+ * While there is something to do, we integrate structs in this order
+ * 1. top element on stack, if stack is not empty
+ * 2. next element from current struct reader (if empty, use next struct reader)
+ *
+ * If struct causally depends on another struct (ref.missing), we put next reader of
+ * `ref.id.client` on top of stack.
+ *
+ * At some point we find a struct that has no causal dependencies,
+ * then we start emptying the stack.
+ *
+ * It is not possible to have circles: i.e. struct1 (from client1) depends on struct2 (from client2)
+ * depends on struct3 (from client1). Therefore the max stack size is eqaul to `structReaders.length`.
+ *
+ * This method is implemented in a way so that we can resume computation if this update
+ * causally depends on another update.
+ *
+ * @param {Transaction} transaction
+ * @param {StructStore} store
+ * @param {Map<number, { i: number, refs: (GC | Item)[] }>} clientsStructRefs
+ * @return { null | { update: Uint8Array, missing: Map<number,number> } }
+ *
+ * @private
+ * @function
+ */
+const integrateStructs = (transaction, store, clientsStructRefs) => {
+  /**
+   * @type {Array<Item | GC>}
+   */
+  const stack = []
+  // sort them so that we take the higher id first, in case of conflicts the lower id will probably not conflict with the id from the higher user.
+  let clientsStructRefsIds = Array.from(clientsStructRefs.keys()).sort((a, b) => a - b)
+  if (clientsStructRefsIds.length === 0) {
+    return null
+  }
+  const getNextStructTarget = () => {
+    if (clientsStructRefsIds.length === 0) {
+      return null
+    }
+    let nextStructsTarget = /** @type {{i:number,refs:Array<GC|Item>}} */ (clientsStructRefs.get(clientsStructRefsIds[clientsStructRefsIds.length - 1]))
+    while (nextStructsTarget.refs.length === nextStructsTarget.i) {
+      clientsStructRefsIds.pop()
+      if (clientsStructRefsIds.length > 0) {
+        nextStructsTarget = /** @type {{i:number,refs:Array<GC|Item>}} */ (clientsStructRefs.get(clientsStructRefsIds[clientsStructRefsIds.length - 1]))
+      } else {
+        return null
+      }
+    }
+    return nextStructsTarget
+  }
+  let curStructsTarget = getNextStructTarget()
+  if (curStructsTarget === null && stack.length === 0) {
+    return null
+  }
+
+  /**
+   * @type {StructStore}
+   */
+  const restStructs = new StructStore()
+  const missingSV = new Map()
+  /**
+   * @param {number} client
+   * @param {number} clock
+   */
+  const updateMissingSv = (client, clock) => {
+    const mclock = missingSV.get(client)
+    if (mclock == null || mclock > clock) {
+      missingSV.set(client, clock)
+    }
+  }
+  /**
+   * @type {GC|Item}
+   */
+  let stackHead = /** @type {any} */ (curStructsTarget).refs[/** @type {any} */ (curStructsTarget).i++]
+  // caching the state because it is used very often
+  const state = new Map()
+
+  const addStackToRestSS = () => {
+    for (const item of stack) {
+      const client = item.id.client
+      const unapplicableItems = clientsStructRefs.get(client)
+      if (unapplicableItems) {
+        // decrement because we weren't able to apply previous operation
+        unapplicableItems.i--
+        restStructs.clients.set(client, unapplicableItems.refs.slice(unapplicableItems.i))
+        clientsStructRefs.delete(client)
+        unapplicableItems.i = 0
+        unapplicableItems.refs = []
+      } else {
+        // item was the last item on clientsStructRefs and the field was already cleared. Add item to restStructs and continue
+        restStructs.clients.set(client, [item])
+      }
+      // remove client from clientsStructRefsIds to prevent users from applying the same update again
+      clientsStructRefsIds = clientsStructRefsIds.filter(c => c !== client)
+    }
+    stack.length = 0
+  }
+
+  // iterate over all struct readers until we are done
+  while (true) {
+    if (stackHead.constructor !== Skip) {
+      const localClock = map.setIfUndefined(state, stackHead.id.client, () => getState(store, stackHead.id.client))
+      const offset = localClock - stackHead.id.clock
+      if (offset < 0) {
+        // update from the same client is missing
+        stack.push(stackHead)
+        updateMissingSv(stackHead.id.client, stackHead.id.clock - 1)
+        // hid a dead wall, add all items from stack to restSS
+        addStackToRestSS()
+      } else {
+        const missing = stackHead.getMissing(transaction, store)
+        if (missing !== null) {
+          stack.push(stackHead)
+          // get the struct reader that has the missing struct
+          /**
+           * @type {{ refs: Array<GC|Item>, i: number }}
+           */
+          const structRefs = clientsStructRefs.get(/** @type {number} */ (missing)) || { refs: [], i: 0 }
+          if (structRefs.refs.length === structRefs.i) {
+            // This update message causally depends on another update message that doesn't exist yet
+            updateMissingSv(/** @type {number} */ (missing), getState(store, missing))
+            addStackToRestSS()
+          } else {
+            stackHead = structRefs.refs[structRefs.i++]
+            continue
+          }
+        } else if (offset === 0 || offset < stackHead.length) {
+          // all fine, apply the stackhead
+          stackHead.integrate(transaction, offset)
+          state.set(stackHead.id.client, stackHead.id.clock + stackHead.length)
+        }
+      }
+    }
+    // iterate to next stackHead
+    if (stack.length > 0) {
+      stackHead = /** @type {GC|Item} */ (stack.pop())
+    } else if (curStructsTarget !== null && curStructsTarget.i < curStructsTarget.refs.length) {
+      stackHead = /** @type {GC|Item} */ (curStructsTarget.refs[curStructsTarget.i++])
+    } else {
+      curStructsTarget = getNextStructTarget()
+      if (curStructsTarget === null) {
+        // we are done!
+        break
+      } else {
+        stackHead = /** @type {GC|Item} */ (curStructsTarget.refs[curStructsTarget.i++])
+      }
+    }
+  }
+  if (restStructs.clients.size > 0) {
+    const encoder = new UpdateEncoderV2()
+    writeClientsStructs(encoder, restStructs, new Map())
+    // write empty deleteset
+    // writeDeleteSet(encoder, new DeleteSet())
+    encoding.writeVarUint(encoder.restEncoder, 0) // => no need for an extra function call, just write 0 deletes
+    return { missing: missingSV, update: encoder.toUint8Array() }
+  }
+  return null
+}
+
+/**
+ * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+ * @param {Transaction} transaction
+ *
+ * @private
+ * @function
+ */
+export const writeStructsFromTransaction = (encoder, transaction) => writeClientsStructs(encoder, transaction.doc.store, transaction.beforeState)
+
+/**
+ * Read and apply a document update.
+ *
+ * This function has the same effect as `applyUpdate` but accepts an decoder.
+ *
+ * @param {decoding.Decoder} decoder
+ * @param {Doc} ydoc
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} [structDecoder]
+ *
+ * @function
+ */
+export const readUpdateV2 = (decoder, ydoc, transactionOrigin, structDecoder = new UpdateDecoderV2(decoder)) =>
+  transact(ydoc, transaction => {
+    // force that transaction.local is set to non-local
+    transaction.local = false
+    let retry = false
+    const doc = transaction.doc
+    const store = doc.store
+    // let start = performance.now()
+    const ss = readClientsStructRefs(structDecoder, doc)
+    // console.log('time to read structs: ', performance.now() - start) // @todo remove
+    // start = performance.now()
+    // console.log('time to merge: ', performance.now() - start) // @todo remove
+    // start = performance.now()
+    const restStructs = integrateStructs(transaction, store, ss)
+    const pending = store.pendingStructs
+    if (pending) {
+      // check if we can apply something
+      for (const [client, clock] of pending.missing) {
+        if (clock < getState(store, client)) {
+          retry = true
+          break
+        }
+      }
+      if (restStructs) {
+        // merge restStructs into store.pending
+        for (const [client, clock] of restStructs.missing) {
+          const mclock = pending.missing.get(client)
+          if (mclock == null || mclock > clock) {
+            pending.missing.set(client, clock)
+          }
+        }
+        pending.update = mergeUpdatesV2([pending.update, restStructs.update])
+      }
+    } else {
+      store.pendingStructs = restStructs
+    }
+    // console.log('time to integrate: ', performance.now() - start) // @todo remove
+    // start = performance.now()
+    const dsRest = readAndApplyDeleteSet(structDecoder, transaction, store)
+    if (store.pendingDs) {
+      // @todo we could make a lower-bound state-vector check as we do above
+      const pendingDSUpdate = new UpdateDecoderV2(decoding.createDecoder(store.pendingDs))
+      decoding.readVarUint(pendingDSUpdate.restDecoder) // read 0 structs, because we only encode deletes in pendingdsupdate
+      const dsRest2 = readAndApplyDeleteSet(pendingDSUpdate, transaction, store)
+      if (dsRest && dsRest2) {
+        // case 1: ds1 != null && ds2 != null
+        store.pendingDs = mergeUpdatesV2([dsRest, dsRest2])
+      } else {
+        // case 2: ds1 != null
+        // case 3: ds2 != null
+        // case 4: ds1 == null && ds2 == null
+        store.pendingDs = dsRest || dsRest2
+      }
+    } else {
+      // Either dsRest == null && pendingDs == null OR dsRest != null
+      store.pendingDs = dsRest
+    }
+    // console.log('time to cleanup: ', performance.now() - start) // @todo remove
+    // start = performance.now()
+
+    // console.log('time to resume delete readers: ', performance.now() - start) // @todo remove
+    // start = performance.now()
+    if (retry) {
+      const update = /** @type {{update: Uint8Array}} */ (store.pendingStructs).update
+      store.pendingStructs = null
+      applyUpdateV2(transaction.doc, update)
+    }
+  }, transactionOrigin, false)
+
+/**
+ * Read and apply a document update.
+ *
+ * This function has the same effect as `applyUpdate` but accepts an decoder.
+ *
+ * @param {decoding.Decoder} decoder
+ * @param {Doc} ydoc
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ *
+ * @function
+ */
+export const readUpdate = (decoder, ydoc, transactionOrigin) => readUpdateV2(decoder, ydoc, transactionOrigin, new UpdateDecoderV1(decoder))
+
+/**
+ * Apply a document update created by, for example, `y.on('update', update => ..)` or `update = encodeStateAsUpdate()`.
+ *
+ * This function has the same effect as `readUpdate` but accepts an Uint8Array instead of a Decoder.
+ *
+ * @param {Doc} ydoc
+ * @param {Uint8Array} update
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ * @param {typeof UpdateDecoderV1 | typeof UpdateDecoderV2} [YDecoder]
+ *
+ * @function
+ */
+export const applyUpdateV2 = (ydoc, update, transactionOrigin, YDecoder = UpdateDecoderV2) => {
+  const decoder = decoding.createDecoder(update)
+  readUpdateV2(decoder, ydoc, transactionOrigin, new YDecoder(decoder))
+}
+
+/**
+ * Apply a document update created by, for example, `y.on('update', update => ..)` or `update = encodeStateAsUpdate()`.
+ *
+ * This function has the same effect as `readUpdate` but accepts an Uint8Array instead of a Decoder.
+ *
+ * @param {Doc} ydoc
+ * @param {Uint8Array} update
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ *
+ * @function
+ */
+export const applyUpdate = (ydoc, update, transactionOrigin) => applyUpdateV2(ydoc, update, transactionOrigin, UpdateDecoderV1)
+
+/**
+ * Write all the document as a single update message. If you specify the state of the remote client (`targetStateVector`) it will
+ * only write the operations that are missing.
+ *
+ * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+ * @param {Doc} doc
+ * @param {Map<number,number>} [targetStateVector] The state of the target that receives the update. Leave empty to write all known structs
+ *
+ * @function
+ */
+export const writeStateAsUpdate = (encoder, doc, targetStateVector = new Map()) => {
+  writeClientsStructs(encoder, doc.store, targetStateVector)
+  writeDeleteSet(encoder, createDeleteSetFromStructStore(doc.store))
+}
+
+/**
+ * Write all the document as a single update message that can be applied on the remote document. If you specify the state of the remote client (`targetState`) it will
+ * only write the operations that are missing.
+ *
+ * Use `writeStateAsUpdate` instead if you are working with lib0/encoding.js#Encoder
+ *
+ * @param {Doc} doc
+ * @param {Uint8Array} [encodedTargetStateVector] The state of the target that receives the update. Leave empty to write all known structs
+ * @param {UpdateEncoderV1 | UpdateEncoderV2} [encoder]
+ * @return {Uint8Array}
+ *
+ * @function
+ */
+export const encodeStateAsUpdateV2 = (doc, encodedTargetStateVector = new Uint8Array([0]), encoder = new UpdateEncoderV2()) => {
+  const targetStateVector = decodeStateVector(encodedTargetStateVector)
+  writeStateAsUpdate(encoder, doc, targetStateVector)
+  const updates = [encoder.toUint8Array()]
+  // also add the pending updates (if there are any)
+  if (doc.store.pendingDs) {
+    updates.push(doc.store.pendingDs)
+  }
+  if (doc.store.pendingStructs) {
+    updates.push(diffUpdateV2(doc.store.pendingStructs.update, encodedTargetStateVector))
+  }
+  if (updates.length > 1) {
+    if (encoder.constructor === UpdateEncoderV1) {
+      return mergeUpdates(updates.map((update, i) => i === 0 ? update : convertUpdateFormatV2ToV1(update)))
+    } else if (encoder.constructor === UpdateEncoderV2) {
+      return mergeUpdatesV2(updates)
+    }
+  }
+  return updates[0]
+}
+
+/**
+ * Write all the document as a single update message that can be applied on the remote document. If you specify the state of the remote client (`targetState`) it will
+ * only write the operations that are missing.
+ *
+ * Use `writeStateAsUpdate` instead if you are working with lib0/encoding.js#Encoder
+ *
+ * @param {Doc} doc
+ * @param {Uint8Array} [encodedTargetStateVector] The state of the target that receives the update. Leave empty to write all known structs
+ * @return {Uint8Array}
+ *
+ * @function
+ */
+export const encodeStateAsUpdate = (doc, encodedTargetStateVector) => encodeStateAsUpdateV2(doc, encodedTargetStateVector, new UpdateEncoderV1())
+
+/**
+ * Read state vector from Decoder and return as Map
+ *
+ * @param {DSDecoderV1 | DSDecoderV2} decoder
+ * @return {Map<number,number>} Maps `client` to the number next expected `clock` from that client.
+ *
+ * @function
+ */
+export const readStateVector = decoder => {
+  const ss = new Map()
+  const ssLength = decoding.readVarUint(decoder.restDecoder)
+  for (let i = 0; i < ssLength; i++) {
+    const client = decoding.readVarUint(decoder.restDecoder)
+    const clock = decoding.readVarUint(decoder.restDecoder)
+    ss.set(client, clock)
+  }
+  return ss
+}
+
+/**
+ * Read decodedState and return State as Map.
+ *
+ * @param {Uint8Array} decodedState
+ * @return {Map<number,number>} Maps `client` to the number next expected `clock` from that client.
+ *
+ * @function
+ */
+// export const decodeStateVectorV2 = decodedState => readStateVector(new DSDecoderV2(decoding.createDecoder(decodedState)))
+
+/**
+ * Read decodedState and return State as Map.
+ *
+ * @param {Uint8Array} decodedState
+ * @return {Map<number,number>} Maps `client` to the number next expected `clock` from that client.
+ *
+ * @function
+ */
+export const decodeStateVector = decodedState => readStateVector(new DSDecoderV1(decoding.createDecoder(decodedState)))
+
+/**
+ * @param {DSEncoderV1 | DSEncoderV2} encoder
+ * @param {Map<number,number>} sv
+ * @function
+ */
+export const writeStateVector = (encoder, sv) => {
+  encoding.writeVarUint(encoder.restEncoder, sv.size)
+  Array.from(sv.entries()).sort((a, b) => b[0] - a[0]).forEach(([client, clock]) => {
+    encoding.writeVarUint(encoder.restEncoder, client) // @todo use a special client decoder that is based on mapping
+    encoding.writeVarUint(encoder.restEncoder, clock)
+  })
+  return encoder
+}
+
+/**
+ * @param {DSEncoderV1 | DSEncoderV2} encoder
+ * @param {Doc} doc
+ *
+ * @function
+ */
+export const writeDocumentStateVector = (encoder, doc) => writeStateVector(encoder, getStateVector(doc.store))
+
+/**
+ * Encode State as Uint8Array.
+ *
+ * @param {Doc|Map<number,number>} doc
+ * @param {DSEncoderV1 | DSEncoderV2} [encoder]
+ * @return {Uint8Array}
+ *
+ * @function
+ */
+export const encodeStateVectorV2 = (doc, encoder = new DSEncoderV2()) => {
+  if (doc instanceof Map) {
+    writeStateVector(encoder, doc)
+  } else {
+    writeDocumentStateVector(encoder, doc)
+  }
+  return encoder.toUint8Array()
+}
+
+/**
+ * Encode State as Uint8Array.
+ *
+ * @param {Doc|Map<number,number>} doc
+ * @return {Uint8Array}
+ *
+ * @function
+ */
+export const encodeStateVector = doc => encodeStateVectorV2(doc, new DSEncoderV1())

src/utils/isParentOf.js

@@ -0,0 +1,22 @@
+
+import { AbstractType, Item } from '../internals.js' // eslint-disable-line
+
+/**
+ * Check if `parent` is a parent of `child`.
+ *
+ * @param {AbstractType<any>} parent
+ * @param {Item|null} child
+ * @return {Boolean} Whether `parent` is a parent of `child`.
+ *
+ * @private
+ * @function
+ */
+export const isParentOf = (parent, child) => {
+  while (child !== null) {
+    if (child.parent === parent) {
+      return true
+    }
+    child = /** @type {AbstractType<any>} */ (child.parent)._item
+  }
+  return false
+}

src/utils/logging.js

@@ -0,0 +1,22 @@
+
+import {
+  AbstractType // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * Convenient helper to log type information.
+ *
+ * Do not use in productive systems as the output can be immense!
+ *
+ * @param {AbstractType<any>} type
+ */
+export const logType = type => {
+  const res = []
+  let n = type._start
+  while (n) {
+    res.push(n)
+    n = n.right
+  }
+  console.log('Children: ', res)
+  console.log('Children content: ', res.filter(m => !m.deleted).map(m => m.content))
+}

src/utils/updates.js

@@ -0,0 +1,557 @@
+
+import * as binary from 'lib0/binary'
+import * as decoding from 'lib0/decoding'
+import * as encoding from 'lib0/encoding'
+import * as logging from 'lib0/logging'
+import * as math from 'lib0/math'
+import {
+  createID,
+  readItemContent,
+  readDeleteSet,
+  writeDeleteSet,
+  Skip,
+  mergeDeleteSets,
+  DSEncoderV1,
+  DSEncoderV2,
+  decodeStateVector,
+  Item, GC, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2 // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ */
+function * lazyStructReaderGenerator (decoder) {
+  const numOfStateUpdates = decoding.readVarUint(decoder.restDecoder)
+  for (let i = 0; i < numOfStateUpdates; i++) {
+    const numberOfStructs = decoding.readVarUint(decoder.restDecoder)
+    const client = decoder.readClient()
+    let clock = decoding.readVarUint(decoder.restDecoder)
+    for (let i = 0; i < numberOfStructs; i++) {
+      const info = decoder.readInfo()
+      // @todo use switch instead of ifs
+      if (info === 10) {
+        const len = decoding.readVarUint(decoder.restDecoder)
+        yield new Skip(createID(client, clock), len)
+        clock += len
+      } else if ((binary.BITS5 & info) !== 0) {
+        const cantCopyParentInfo = (info & (binary.BIT7 | binary.BIT8)) === 0
+        // If parent = null and neither left nor right are defined, then we know that `parent` is child of `y`
+        // and we read the next string as parentYKey.
+        // It indicates how we store/retrieve parent from `y.share`
+        // @type {string|null}
+        const struct = new Item(
+          createID(client, clock),
+          null, // left
+          (info & binary.BIT8) === binary.BIT8 ? decoder.readLeftID() : null, // origin
+          null, // right
+          (info & binary.BIT7) === binary.BIT7 ? decoder.readRightID() : null, // right origin
+          // @ts-ignore Force writing a string here.
+          cantCopyParentInfo ? (decoder.readParentInfo() ? decoder.readString() : decoder.readLeftID()) : null, // parent
+          cantCopyParentInfo && (info & binary.BIT6) === binary.BIT6 ? decoder.readString() : null, // parentSub
+          readItemContent(decoder, info) // item content
+        )
+        yield struct
+        clock += struct.length
+      } else {
+        const len = decoder.readLen()
+        yield new GC(createID(client, clock), len)
+        clock += len
+      }
+    }
+  }
+}
+
+export class LazyStructReader {
+  /**
+   * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+   * @param {boolean} filterSkips
+   */
+  constructor (decoder, filterSkips) {
+    this.gen = lazyStructReaderGenerator(decoder)
+    /**
+     * @type {null | Item | Skip | GC}
+     */
+    this.curr = null
+    this.done = false
+    this.filterSkips = filterSkips
+    this.next()
+  }
+
+  /**
+   * @return {Item | GC | Skip |null}
+   */
+  next () {
+    // ignore "Skip" structs
+    do {
+      this.curr = this.gen.next().value || null
+    } while (this.filterSkips && this.curr !== null && this.curr.constructor === Skip)
+    return this.curr
+  }
+}
+
+/**
+ * @param {Uint8Array} update
+ *
+ */
+export const logUpdate = update => logUpdateV2(update, UpdateDecoderV1)
+
+/**
+ * @param {Uint8Array} update
+ * @param {typeof UpdateDecoderV2 | typeof UpdateDecoderV1} [YDecoder]
+ *
+ */
+export const logUpdateV2 = (update, YDecoder = UpdateDecoderV2) => {
+  const structs = []
+  const updateDecoder = new YDecoder(decoding.createDecoder(update))
+  const lazyDecoder = new LazyStructReader(updateDecoder, false)
+  for (let curr = lazyDecoder.curr; curr !== null; curr = lazyDecoder.next()) {
+    structs.push(curr)
+  }
+  logging.print('Structs: ', structs)
+  const ds = readDeleteSet(updateDecoder)
+  logging.print('DeleteSet: ', ds)
+}
+
+export class LazyStructWriter {
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   */
+  constructor (encoder) {
+    this.currClient = 0
+    this.startClock = 0
+    this.written = 0
+    this.encoder = encoder
+    /**
+     * We want to write operations lazily, but also we need to know beforehand how many operations we want to write for each client.
+     *
+     * This kind of meta-information (#clients, #structs-per-client-written) is written to the restEncoder.
+     *
+     * We fragment the restEncoder and store a slice of it per-client until we know how many clients there are.
+     * When we flush (toUint8Array) we write the restEncoder using the fragments and the meta-information.
+     *
+     * @type {Array<{ written: number, restEncoder: Uint8Array }>}
+     */
+    this.clientStructs = []
+  }
+}
+
+/**
+ * @param {Array<Uint8Array>} updates
+ * @return {Uint8Array}
+ */
+export const mergeUpdates = updates => mergeUpdatesV2(updates, UpdateDecoderV1, UpdateEncoderV1)
+
+/**
+ * @param {Uint8Array} update
+ * @param {typeof DSEncoderV1 | typeof DSEncoderV2} YEncoder
+ * @param {typeof UpdateDecoderV1 | typeof UpdateDecoderV2} YDecoder
+ * @return {Uint8Array}
+ */
+export const encodeStateVectorFromUpdateV2 = (update, YEncoder = DSEncoderV2, YDecoder = UpdateDecoderV2) => {
+  const encoder = new YEncoder()
+  const updateDecoder = new LazyStructReader(new YDecoder(decoding.createDecoder(update)), false)
+  let curr = updateDecoder.curr
+  if (curr !== null) {
+    let size = 0
+    let currClient = curr.id.client
+    let stopCounting = curr.id.clock !== 0 // must start at 0
+    let currClock = stopCounting ? 0 : curr.id.clock + curr.length
+    for (; curr !== null; curr = updateDecoder.next()) {
+      if (currClient !== curr.id.client) {
+        if (currClock !== 0) {
+          size++
+          // We found a new client
+          // write what we have to the encoder
+          encoding.writeVarUint(encoder.restEncoder, currClient)
+          encoding.writeVarUint(encoder.restEncoder, currClock)
+        }
+        currClient = curr.id.client
+        currClock = 0
+        stopCounting = curr.id.clock !== 0
+      }
+      // we ignore skips
+      if (curr.constructor === Skip) {
+        stopCounting = true
+      }
+      if (!stopCounting) {
+        currClock = curr.id.clock + curr.length
+      }
+    }
+    // write what we have
+    if (currClock !== 0) {
+      size++
+      encoding.writeVarUint(encoder.restEncoder, currClient)
+      encoding.writeVarUint(encoder.restEncoder, currClock)
+    }
+    // prepend the size of the state vector
+    const enc = encoding.createEncoder()
+    encoding.writeVarUint(enc, size)
+    encoding.writeBinaryEncoder(enc, encoder.restEncoder)
+    encoder.restEncoder = enc
+    return encoder.toUint8Array()
+  } else {
+    encoding.writeVarUint(encoder.restEncoder, 0)
+    return encoder.toUint8Array()
+  }
+}
+
+/**
+ * @param {Uint8Array} update
+ * @return {Uint8Array}
+ */
+export const encodeStateVectorFromUpdate = update => encodeStateVectorFromUpdateV2(update, DSEncoderV1, UpdateDecoderV1)
+
+/**
+ * @param {Uint8Array} update
+ * @param {typeof UpdateDecoderV1 | typeof UpdateDecoderV2} YDecoder
+ * @return {{ from: Map<number,number>, to: Map<number,number> }}
+ */
+export const parseUpdateMetaV2 = (update, YDecoder = UpdateDecoderV2) => {
+  /**
+   * @type {Map<number, number>}
+   */
+  const from = new Map()
+  /**
+   * @type {Map<number, number>}
+   */
+  const to = new Map()
+  const updateDecoder = new LazyStructReader(new YDecoder(decoding.createDecoder(update)), false)
+  let curr = updateDecoder.curr
+  if (curr !== null) {
+    let currClient = curr.id.client
+    let currClock = curr.id.clock
+    // write the beginning to `from`
+    from.set(currClient, currClock)
+    for (; curr !== null; curr = updateDecoder.next()) {
+      if (currClient !== curr.id.client) {
+        // We found a new client
+        // write the end to `to`
+        to.set(currClient, currClock)
+        // write the beginning to `from`
+        from.set(curr.id.client, curr.id.clock)
+        // update currClient
+        currClient = curr.id.client
+      }
+      currClock = curr.id.clock + curr.length
+    }
+    // write the end to `to`
+    to.set(currClient, currClock)
+  }
+  return { from, to }
+}
+
+/**
+ * @param {Uint8Array} update
+ * @return {{ from: Map<number,number>, to: Map<number,number> }}
+ */
+export const parseUpdateMeta = update => parseUpdateMetaV2(update, UpdateDecoderV1)
+
+/**
+ * This method is intended to slice any kind of struct and retrieve the right part.
+ * It does not handle side-effects, so it should only be used by the lazy-encoder.
+ *
+ * @param {Item | GC | Skip} left
+ * @param {number} diff
+ * @return {Item | GC}
+ */
+const sliceStruct = (left, diff) => {
+  if (left.constructor === GC) {
+    const { client, clock } = left.id
+    return new GC(createID(client, clock + diff), left.length - diff)
+  } else if (left.constructor === Skip) {
+    const { client, clock } = left.id
+    return new Skip(createID(client, clock + diff), left.length - diff)
+  } else {
+    const leftItem = /** @type {Item} */ (left)
+    const { client, clock } = leftItem.id
+    return new Item(
+      createID(client, clock + diff),
+      null,
+      createID(client, clock + diff - 1),
+      null,
+      leftItem.rightOrigin,
+      leftItem.parent,
+      leftItem.parentSub,
+      leftItem.content.splice(diff)
+    )
+  }
+}
+
+/**
+ *
+ * This function works similarly to `readUpdateV2`.
+ *
+ * @param {Array<Uint8Array>} updates
+ * @param {typeof UpdateDecoderV1 | typeof UpdateDecoderV2} [YDecoder]
+ * @param {typeof UpdateEncoderV1 | typeof UpdateEncoderV2} [YEncoder]
+ * @return {Uint8Array}
+ */
+export const mergeUpdatesV2 = (updates, YDecoder = UpdateDecoderV2, YEncoder = UpdateEncoderV2) => {
+  if (updates.length === 1) {
+    return updates[0]
+  }
+  const updateDecoders = updates.map(update => new YDecoder(decoding.createDecoder(update)))
+  let lazyStructDecoders = updateDecoders.map(decoder => new LazyStructReader(decoder, true))
+
+  /**
+   * @todo we don't need offset because we always slice before
+   * @type {null | { struct: Item | GC | Skip, offset: number }}
+   */
+  let currWrite = null
+
+  const updateEncoder = new YEncoder()
+  // write structs lazily
+  const lazyStructEncoder = new LazyStructWriter(updateEncoder)
+
+  // Note: We need to ensure that all lazyStructDecoders are fully consumed
+  // Note: Should merge document updates whenever possible - even from different updates
+  // Note: Should handle that some operations cannot be applied yet ()
+
+  while (true) {
+    // Write higher clients first ⇒ sort by clientID & clock and remove decoders without content
+    lazyStructDecoders = lazyStructDecoders.filter(dec => dec.curr !== null)
+    lazyStructDecoders.sort(
+      /** @type {function(any,any):number} */ (dec1, dec2) => {
+        if (dec1.curr.id.client === dec2.curr.id.client) {
+          const clockDiff = dec1.curr.id.clock - dec2.curr.id.clock
+          if (clockDiff === 0) {
+            // @todo remove references to skip since the structDecoders must filter Skips.
+            return dec1.curr.constructor === dec2.curr.constructor
+              ? 0
+              : dec1.curr.constructor === Skip ? 1 : -1 // we are filtering skips anyway.
+          } else {
+            return clockDiff
+          }
+        } else {
+          return dec2.curr.id.client - dec1.curr.id.client
+        }
+      }
+    )
+    if (lazyStructDecoders.length === 0) {
+      break
+    }
+    const currDecoder = lazyStructDecoders[0]
+    // write from currDecoder until the next operation is from another client or if filler-struct
+    // then we need to reorder the decoders and find the next operation to write
+    const firstClient = /** @type {Item | GC} */ (currDecoder.curr).id.client
+
+    if (currWrite !== null) {
+      let curr = /** @type {Item | GC | null} */ (currDecoder.curr)
+      let iterated = false
+
+      // iterate until we find something that we haven't written already
+      // remember: first the high client-ids are written
+      while (curr !== null && curr.id.clock + curr.length <= currWrite.struct.id.clock + currWrite.struct.length && curr.id.client >= currWrite.struct.id.client) {
+        curr = currDecoder.next()
+        iterated = true
+      }
+      if (
+        curr === null || // current decoder is empty
+        curr.id.client !== firstClient || // check whether there is another decoder that has has updates from `firstClient`
+        (iterated && curr.id.clock > currWrite.struct.id.clock + currWrite.struct.length) // the above while loop was used and we are potentially missing updates
+      ) {
+        continue
+      }
+
+      if (firstClient !== currWrite.struct.id.client) {
+        writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)
+        currWrite = { struct: curr, offset: 0 }
+        currDecoder.next()
+      } else {
+        if (currWrite.struct.id.clock + currWrite.struct.length < curr.id.clock) {
+          // @todo write currStruct & set currStruct = Skip(clock = currStruct.id.clock + currStruct.length, length = curr.id.clock - self.clock)
+          if (currWrite.struct.constructor === Skip) {
+            // extend existing skip
+            currWrite.struct.length = curr.id.clock + curr.length - currWrite.struct.id.clock
+          } else {
+            writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)
+            const diff = curr.id.clock - currWrite.struct.id.clock - currWrite.struct.length
+            /**
+             * @type {Skip}
+             */
+            const struct = new Skip(createID(firstClient, currWrite.struct.id.clock + currWrite.struct.length), diff)
+            currWrite = { struct, offset: 0 }
+          }
+        } else { // if (currWrite.struct.id.clock + currWrite.struct.length >= curr.id.clock) {
+          const diff = currWrite.struct.id.clock + currWrite.struct.length - curr.id.clock
+          if (diff > 0) {
+            if (currWrite.struct.constructor === Skip) {
+              // prefer to slice Skip because the other struct might contain more information
+              currWrite.struct.length -= diff
+            } else {
+              curr = sliceStruct(curr, diff)
+            }
+          }
+          if (!currWrite.struct.mergeWith(/** @type {any} */ (curr))) {
+            writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)
+            currWrite = { struct: curr, offset: 0 }
+            currDecoder.next()
+          }
+        }
+      }
+    } else {
+      currWrite = { struct: /** @type {Item | GC} */ (currDecoder.curr), offset: 0 }
+      currDecoder.next()
+    }
+    for (
+      let next = currDecoder.curr;
+      next !== null && next.id.client === firstClient && next.id.clock === currWrite.struct.id.clock + currWrite.struct.length && next.constructor !== Skip;
+      next = currDecoder.next()
+    ) {
+      writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)
+      currWrite = { struct: next, offset: 0 }
+    }
+  }
+  if (currWrite !== null) {
+    writeStructToLazyStructWriter(lazyStructEncoder, currWrite.struct, currWrite.offset)
+    currWrite = null
+  }
+  finishLazyStructWriting(lazyStructEncoder)
+
+  const dss = updateDecoders.map(decoder => readDeleteSet(decoder))
+  const ds = mergeDeleteSets(dss)
+  writeDeleteSet(updateEncoder, ds)
+  return updateEncoder.toUint8Array()
+}
+
+/**
+ * @param {Uint8Array} update
+ * @param {Uint8Array} sv
+ * @param {typeof UpdateDecoderV1 | typeof UpdateDecoderV2} [YDecoder]
+ * @param {typeof UpdateEncoderV1 | typeof UpdateEncoderV2} [YEncoder]
+ */
+export const diffUpdateV2 = (update, sv, YDecoder = UpdateDecoderV2, YEncoder = UpdateEncoderV2) => {
+  const state = decodeStateVector(sv)
+  const encoder = new YEncoder()
+  const lazyStructWriter = new LazyStructWriter(encoder)
+  const decoder = new YDecoder(decoding.createDecoder(update))
+  const reader = new LazyStructReader(decoder, false)
+  while (reader.curr) {
+    const curr = reader.curr
+    const currClient = curr.id.client
+    const svClock = state.get(currClient) || 0
+    if (reader.curr.constructor === Skip) {
+      // the first written struct shouldn't be a skip
+      reader.next()
+      continue
+    }
+    if (curr.id.clock + curr.length > svClock) {
+      writeStructToLazyStructWriter(lazyStructWriter, curr, math.max(svClock - curr.id.clock, 0))
+      reader.next()
+      while (reader.curr && reader.curr.id.client === currClient) {
+        writeStructToLazyStructWriter(lazyStructWriter, reader.curr, 0)
+        reader.next()
+      }
+    } else {
+      // read until something new comes up
+      while (reader.curr && reader.curr.id.client === currClient && reader.curr.id.clock + reader.curr.length <= svClock) {
+        reader.next()
+      }
+    }
+  }
+  finishLazyStructWriting(lazyStructWriter)
+  // write ds
+  const ds = readDeleteSet(decoder)
+  writeDeleteSet(encoder, ds)
+  return encoder.toUint8Array()
+}
+
+/**
+ * @param {Uint8Array} update
+ * @param {Uint8Array} sv
+ */
+export const diffUpdate = (update, sv) => diffUpdateV2(update, sv, UpdateDecoderV1, UpdateEncoderV1)
+
+/**
+ * @param {LazyStructWriter} lazyWriter
+ */
+const flushLazyStructWriter = lazyWriter => {
+  if (lazyWriter.written > 0) {
+    lazyWriter.clientStructs.push({ written: lazyWriter.written, restEncoder: encoding.toUint8Array(lazyWriter.encoder.restEncoder) })
+    lazyWriter.encoder.restEncoder = encoding.createEncoder()
+    lazyWriter.written = 0
+  }
+}
+
+/**
+ * @param {LazyStructWriter} lazyWriter
+ * @param {Item | GC} struct
+ * @param {number} offset
+ */
+const writeStructToLazyStructWriter = (lazyWriter, struct, offset) => {
+  // flush curr if we start another client
+  if (lazyWriter.written > 0 && lazyWriter.currClient !== struct.id.client) {
+    flushLazyStructWriter(lazyWriter)
+  }
+  if (lazyWriter.written === 0) {
+    lazyWriter.currClient = struct.id.client
+    // write next client
+    lazyWriter.encoder.writeClient(struct.id.client)
+    // write startClock
+    encoding.writeVarUint(lazyWriter.encoder.restEncoder, struct.id.clock + offset)
+  }
+  struct.write(lazyWriter.encoder, offset)
+  lazyWriter.written++
+}
+/**
+ * Call this function when we collected all parts and want to
+ * put all the parts together. After calling this method,
+ * you can continue using the UpdateEncoder.
+ *
+ * @param {LazyStructWriter} lazyWriter
+ */
+const finishLazyStructWriting = (lazyWriter) => {
+  flushLazyStructWriter(lazyWriter)
+
+  // this is a fresh encoder because we called flushCurr
+  const restEncoder = lazyWriter.encoder.restEncoder
+
+  /**
+   * Now we put all the fragments together.
+   * This works similarly to `writeClientsStructs`
+   */
+
+  // write # states that were updated - i.e. the clients
+  encoding.writeVarUint(restEncoder, lazyWriter.clientStructs.length)
+
+  for (let i = 0; i < lazyWriter.clientStructs.length; i++) {
+    const partStructs = lazyWriter.clientStructs[i]
+    /**
+     * Works similarly to `writeStructs`
+     */
+    // write # encoded structs
+    encoding.writeVarUint(restEncoder, partStructs.written)
+    // write the rest of the fragment
+    encoding.writeUint8Array(restEncoder, partStructs.restEncoder)
+  }
+}
+
+/**
+ * @param {Uint8Array} update
+ * @param {typeof UpdateDecoderV2 | typeof UpdateDecoderV1} YDecoder
+ * @param {typeof UpdateEncoderV2 | typeof UpdateEncoderV1 } YEncoder
+ */
+export const convertUpdateFormat = (update, YDecoder, YEncoder) => {
+  const updateDecoder = new YDecoder(decoding.createDecoder(update))
+  const lazyDecoder = new LazyStructReader(updateDecoder, false)
+  const updateEncoder = new YEncoder()
+  const lazyWriter = new LazyStructWriter(updateEncoder)
+
+  for (let curr = lazyDecoder.curr; curr !== null; curr = lazyDecoder.next()) {
+    writeStructToLazyStructWriter(lazyWriter, curr, 0)
+  }
+  finishLazyStructWriting(lazyWriter)
+  const ds = readDeleteSet(updateDecoder)
+  writeDeleteSet(updateEncoder, ds)
+  return updateEncoder.toUint8Array()
+}
+
+/**
+ * @param {Uint8Array} update
+ */
+export const convertUpdateFormatV1ToV2 = update => convertUpdateFormat(update, UpdateDecoderV1, UpdateEncoderV2)
+
+/**
+ * @param {Uint8Array} update
+ */
+export const convertUpdateFormatV2ToV1 = update => convertUpdateFormat(update, UpdateDecoderV2, UpdateEncoderV1)

src/y.js

@@ -1,241 +0,0 @@
-import debug from 'debug'
-import extendConnector from './Connector.js'
-import extendDatabase from './Database.js'
-import extendTransaction from './Transaction.js'
-import extendStruct from './Struct.js'
-import extendUtils from './Utils.js'
-
-extendConnector(Y)
-extendDatabase(Y)
-extendTransaction(Y)
-extendStruct(Y)
-extendUtils(Y)
-
-Y.debug = debug
-
-var requiringModules = {}
-
-Y.requiringModules = requiringModules
-
-Y.extend = function (name, value) {
-  if (arguments.length === 2 && typeof name === 'string') {
-    if (value instanceof Y.utils.CustomTypeDefinition) {
-      Y[name] = value.parseArguments
-    } else {
-      Y[name] = value
-    }
-    if (requiringModules[name] != null) {
-      requiringModules[name].resolve()
-      delete requiringModules[name]
-    }
-  } else {
-    for (var i = 0; i < arguments.length; i++) {
-      var f = arguments[i]
-      if (typeof f === 'function') {
-        f(Y)
-      } else {
-        throw new Error('Expected function!')
-      }
-    }
-  }
-}
-
-Y.requestModules = requestModules
-function requestModules (modules) {
-  var sourceDir
-  if (Y.sourceDir === null) {
-    sourceDir = null
-  } else {
-    sourceDir = Y.sourceDir || '/bower_components'
-  }
-  // determine if this module was compiled for es5 or es6 (y.js vs. y.es6)
-  // if Insert.execute is a Function, then it isnt a generator..
-  // then load the es5(.js) files..
-  var extention = typeof regeneratorRuntime !== 'undefined' ? '.js' : '.es6'
-  var promises = []
-  for (var i = 0; i < modules.length; i++) {
-    var module = modules[i].split('(')[0]
-    var modulename = 'y-' + module.toLowerCase()
-    if (Y[module] == null) {
-      if (requiringModules[module] == null) {
-        // module does not exist
-        if (typeof window !== 'undefined' && window.Y !== 'undefined') {
-          if (sourceDir != null) {
-            var imported = document.createElement('script')
-            imported.src = sourceDir + '/' + modulename + '/' + modulename + extention
-            document.head.appendChild(imported)
-          }
-          let requireModule = {}
-          requiringModules[module] = requireModule
-          requireModule.promise = new Promise(function (resolve) {
-            requireModule.resolve = resolve
-          })
-          promises.push(requireModule.promise)
-        } else {
-          console.info('YJS: Please do not depend on automatic requiring of modules anymore! Extend modules as follows `require(\'y-modulename\')(Y)`')
-          require(modulename)(Y)
-        }
-      } else {
-        promises.push(requiringModules[modules[i]].promise)
-      }
-    }
-  }
-  return Promise.all(promises)
-}
-
-/* ::
-type MemoryOptions = {
-  name: 'memory'
-}
-type IndexedDBOptions = {
-  name: 'indexeddb',
-  namespace: string
-}
-type DbOptions = MemoryOptions | IndexedDBOptions
-
-type WebRTCOptions = {
-  name: 'webrtc',
-  room: string
-}
-type WebsocketsClientOptions = {
-  name: 'websockets-client',
-  room: string
-}
-type ConnectionOptions = WebRTCOptions | WebsocketsClientOptions
-
-type YOptions = {
-  connector: ConnectionOptions,
-  db: DbOptions,
-  types: Array<TypeName>,
-  sourceDir: string,
-  share: {[key: string]: TypeName}
-}
-*/
-
-export default function Y (opts/* :YOptions */) /* :Promise<YConfig> */ {
-  if (opts.hasOwnProperty('sourceDir')) {
-    Y.sourceDir = opts.sourceDir
-  }
-  opts.types = opts.types != null ? opts.types : []
-  var modules = [opts.db.name, opts.connector.name].concat(opts.types)
-  for (var name in opts.share) {
-    modules.push(opts.share[name])
-  }
-  return new Promise(function (resolve, reject) {
-    if (opts == null) reject(new Error('An options object is expected!'))
-    else if (opts.connector == null) reject(new Error('You must specify a connector! (missing connector property)'))
-    else if (opts.connector.name == null) reject(new Error('You must specify connector name! (missing connector.name property)'))
-    else if (opts.db == null) reject(new Error('You must specify a database! (missing db property)'))
-    else if (opts.connector.name == null) reject(new Error('You must specify db name! (missing db.name property)'))
-    else {
-      opts = Y.utils.copyObject(opts)
-      opts.connector = Y.utils.copyObject(opts.connector)
-      opts.db = Y.utils.copyObject(opts.db)
-      opts.share = Y.utils.copyObject(opts.share)
-      Y.requestModules(modules).then(function () {
-        var yconfig = new YConfig(opts)
-        yconfig.db.whenUserIdSet(function () {
-          yconfig.init(function () {
-            resolve(yconfig)
-          })
-        })
-      }).catch(reject)
-    }
-  })
-}
-
-class YConfig extends Y.utils.NamedEventHandler {
-  /* ::
-  db: Y.AbstractDatabase;
-  connector: Y.AbstractConnector;
-  share: {[key: string]: any};
-  options: Object;
-  */
-  constructor (opts, callback) {
-    super()
-    this.options = opts
-    this.db = new Y[opts.db.name](this, opts.db)
-    this.connector = new Y[opts.connector.name](this, opts.connector)
-    this.connected = true
-  }
-  init (callback) {
-    var opts = this.options
-    var share = {}
-    this.share = share
-    this.db.requestTransaction(function * requestTransaction () {
-      // create shared object
-      for (var propertyname in opts.share) {
-        var typeConstructor = opts.share[propertyname].split('(')
-        var typeName = typeConstructor.splice(0, 1)
-        var type = Y[typeName]
-        var typedef = type.typeDefinition
-        var id = ['_', typedef.struct + '_' + typeName + '_' + propertyname + '_' + typeConstructor]
-        var args = []
-        if (typeConstructor.length === 1) {
-          try {
-            args = JSON.parse('[' + typeConstructor[0].split(')')[0] + ']')
-          } catch (e) {
-            throw new Error('Was not able to parse type definition! (share.' + propertyname + ')')
-          }
-          if (type.typeDefinition.parseArguments == null) {
-            throw new Error(typeName + ' does not expect arguments!')
-          } else {
-            args = typedef.parseArguments(args[0])[1]
-          }
-        }
-        share[propertyname] = yield * this.store.initType.call(this, id, args)
-      }
-      this.store.whenTransactionsFinished()
-        .then(callback)
-    })
-  }
-  isConnected () {
-    return this.connector.isSynced
-  }
-  disconnect () {
-    if (this.connected) {
-      this.connected = false
-      return this.connector.disconnect()
-    } else {
-      return Promise.resolve()
-    }
-  }
-  reconnect () {
-    if (!this.connected) {
-      this.connected = true
-      return this.connector.reconnect()
-    } else {
-      return Promise.resolve()
-    }
-  }
-  destroy () {
-    var self = this
-    return this.close().then(function () {
-      if (self.db.deleteDB != null) {
-        return self.db.deleteDB()
-      } else {
-        return Promise.resolve()
-      }
-    }).then(() => {
-      // remove existing event listener
-      super.destroy()
-    })
-  }
-  close () {
-    var self = this
-    this.share = null
-    if (this.connector.destroy != null) {
-      this.connector.destroy()
-    } else {
-      this.connector.disconnect()
-    }
-    return this.db.whenTransactionsFinished().then(function () {
-      self.db.destroyTypes()
-      // make sure to wait for all transactions before destroying the db
-      self.db.requestTransaction(function * () {
-        yield * self.db.destroy()
-      })
-      return self.db.whenTransactionsFinished()
-    })
-  }
-}

test.html

@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Testing Yjs</title>
+</head>
+<body>
+  <script type="module" src="./dist/tests.js"></script>
+</body>
+</html>

tests-lib/helper.js

@@ -1,191 +0,0 @@
-
-import _Y from '../../yjs/src/y.js'
-
-import yMemory from '../../y-memory/src/y-memory.js'
-import yArray from '../../y-array/src/y-array.js'
-import yMap from '../../y-map/src/Map.js'
-import yTest from './test-connector.js'
-
-import Chance from 'chance'
-
-export let Y = _Y
-
-Y.extend(yMemory, yArray, yMap, yTest)
-
-export async function garbageCollectUsers (t, users) {
-  await flushAll(t, users)
-  await Promise.all(users.map(u => u.db.emptyGarbageCollector()))
-}
-
-/*
- * 1. reconnect and flush all
- * 2. user 0 gc
- * 3. get type content
- * 4. disconnect & reconnect all (so gc is propagated)
- * 5. compare os, ds, ss
- */
-export async function compareUsers (t, users) {
-  await Promise.all(users.map(u => u.reconnect()))
-  if (users[0].connector.testRoom == null) {
-    await wait(100)
-  }
-  await flushAll(t, users)
-  await wait()
-  await flushAll(t, users)
-
-  var userTypeContents = users.map(u => u.share.array._content.map(c => c.val || JSON.stringify(c.type)))
-
-  await users[0].db.garbageCollect()
-  await users[0].db.garbageCollect()
-
-  // disconnect all except user 0
-  await Promise.all(users.slice(1).map(async u =>
-    u.disconnect()
-  ))
-  if (users[0].connector.testRoom == null) {
-    await wait(100)
-  }
-  // reconnect all
-  await Promise.all(users.map(u => u.reconnect()))
-  if (users[0].connector.testRoom == null) {
-    await wait(100)
-  }
-  await users[0].connector.testRoom.flushAll(users)
-  await Promise.all(users.map(u =>
-    new Promise(function (resolve) {
-      u.connector.whenSynced(resolve)
-    })
-  ))
-  let filterDeletedOps = users.every(u => u.db.gc === false)
-  var data = await Promise.all(users.map(async (u) => {
-    var data = {}
-    u.db.requestTransaction(function * () {
-      var os = yield * this.getOperationsUntransformed()
-      data.os = {}
-      for (let i = 0; i < os.untransformed.length; i++) {
-        let op = os.untransformed[i]
-        op = Y.Struct[op.struct].encode(op)
-        delete op.origin
-        /*
-          If gc = false, it is necessary to filter deleted ops
-          as they might have been split up differently..
-         */
-        if (filterDeletedOps) {
-          let opIsDeleted = yield * this.isDeleted(op.id)
-          if (!opIsDeleted) {
-            data.os[JSON.stringify(op.id)] = op
-          }
-        } else {
-          data.os[JSON.stringify(op.id)] = op
-        }
-      }
-      data.ds = yield * this.getDeleteSet()
-      data.ss = yield * this.getStateSet()
-    })
-    await u.db.whenTransactionsFinished()
-    return data
-  }))
-  for (var i = 0; i < data.length - 1; i++) {
-    await t.asyncGroup(async () => {
-      t.compare(userTypeContents[i], userTypeContents[i + 1], 'types')
-      t.compare(data[i].os, data[i + 1].os, 'os')
-      t.compare(data[i].ds, data[i + 1].ds, 'ds')
-      t.compare(data[i].ss, data[i + 1].ss, 'ss')
-    }, `Compare user${i} with user${i + 1}`)
-  }
-  await Promise.all(users.map(async (u) => {
-    await u.close()
-  }))
-}
-
-export async function initArrays (t, opts) {
-  var result = {
-    users: []
-  }
-  var share = Object.assign({ flushHelper: 'Map', array: 'Array' }, opts.share)
-  var chance = opts.chance || new Chance(t.getSeed() * 1000000000)
-  var connector = Object.assign({ room: 'debugging_' + t.name, testContext: t, chance }, opts.connector)
-  for (let i = 0; i < opts.users; i++) {
-    let dbOpts
-    let connOpts
-    if (i === 0) {
-      // Only one instance can gc!
-      dbOpts = Object.assign({ gc: true }, opts.db)
-      connOpts = Object.assign({ role: 'master' }, connector)
-    } else {
-      dbOpts = Object.assign({ gc: false }, opts.db)
-      connOpts = Object.assign({ role: 'slave' }, connector)
-    }
-    let y = await Y({
-      connector: connOpts,
-      db: dbOpts,
-      share: share
-    })
-    result.users.push(y)
-    for (let name in share) {
-      result[name + i] = y.share[name]
-    }
-  }
-  result.array0.delete(0, result.array0.length)
-  if (result.users[0].connector.testRoom != null) {
-    // flush for sync if test-connector
-    await result.users[0].connector.testRoom.flushAll(result.users)
-  }
-  await Promise.all(result.users.map(u => {
-    return new Promise(function (resolve) {
-      u.connector.whenSynced(resolve)
-    })
-  }))
-  await flushAll(t, result.users)
-  return result
-}
-
-export async function flushAll (t, users) {
-  // users = users.filter(u => u.connector.isSynced)
-  if (users.length === 0) {
-    return
-  }
-  await wait(0)
-  if (users[0].connector.testRoom != null) {
-    // use flushAll method specified in Test Connector
-    await users[0].connector.testRoom.flushAll(users)
-  } else {
-    // flush for any connector
-    await Promise.all(users.map(u => { return u.db.whenTransactionsFinished() }))
-
-    var flushCounter = users[0].share.flushHelper.get('0') || 0
-    flushCounter++
-    await Promise.all(users.map(async (u, i) => {
-      // wait for all users to set the flush counter to the same value
-      await new Promise(resolve => {
-        function observer () {
-          var allUsersReceivedUpdate = true
-          for (var i = 0; i < users.length; i++) {
-            if (u.share.flushHelper.get(i + '') !== flushCounter) {
-              allUsersReceivedUpdate = false
-              break
-            }
-          }
-          if (allUsersReceivedUpdate) {
-            resolve()
-          }
-        }
-        u.share.flushHelper.observe(observer)
-        u.share.flushHelper.set(i + '', flushCounter)
-      })
-    }))
-  }
-}
-
-export async function flushSome (t, users) {
-  if (users[0].connector.testRoom == null) {
-    // if not test-connector, wait for some time for operations to arrive
-    await wait(100)
-  }
-}
-
-export function wait (t) {
-  return new Promise(function (resolve) {
-    setTimeout(resolve, t != null ? t : 100)
-  })
-}

tests-lib/test-connector.js

@@ -1,156 +0,0 @@
-/* global Y */
-import { wait } from './helper.js'
-
-var rooms = {}
-
-export class TestRoom {
-  constructor (roomname) {
-    this.room = roomname
-    this.users = {}
-    this.nextUserId = 0
-  }
-  join (connector) {
-    if (connector.userId == null) {
-      connector.setUserId('' + (this.nextUserId++))
-    }
-    Object.keys(this.users).forEach(uid => {
-      let user = this.users[uid]
-      if (user.role === 'master' || connector.role === 'master') {
-        this.users[uid].userJoined(connector.userId, connector.role)
-        connector.userJoined(uid, this.users[uid].role)
-      }
-    })
-    this.users[connector.userId] = connector
-  }
-  leave (connector) {
-    delete this.users[connector.userId]
-    Object.keys(this.users).forEach(uid => {
-      this.users[uid].userLeft(connector.userId)
-    })
-  }
-  send (sender, receiver, m) {
-    m = JSON.parse(JSON.stringify(m))
-    var user = this.users[receiver]
-    if (user != null) {
-      user.receiveMessage(sender, m)
-    }
-  }
-  broadcast (sender, m) {
-    Object.keys(this.users).forEach(receiver => {
-      this.send(sender, receiver, m)
-    })
-  }
-  async flushAll (users) {
-    let flushing = true
-    let allUserIds = Object.keys(this.users)
-    if (users == null) {
-      users = allUserIds.map(id => this.users[id].y)
-    }
-    while (flushing) {
-      await wait(10)
-      let res = await Promise.all(allUserIds.map(id => this.users[id]._flushAll(users)))
-      flushing = res.some(status => status === 'flushing')
-    }
-  }
-}
-
-function getTestRoom (roomname) {
-  if (rooms[roomname] == null) {
-    rooms[roomname] = new TestRoom(roomname)
-  }
-  return rooms[roomname]
-}
-
-export default function extendTestConnector (Y) {
-  class TestConnector extends Y.AbstractConnector {
-    constructor (y, options) {
-      if (options === undefined) {
-        throw new Error('Options must not be undefined!')
-      }
-      if (options.room == null) {
-        throw new Error('You must define a room name!')
-      }
-      options.forwardAppliedOperations = options.role === 'master'
-      super(y, options)
-      this.options = options
-      this.room = options.room
-      this.chance = options.chance
-      this.testRoom = getTestRoom(this.room)
-      this.testRoom.join(this)
-    }
-    disconnect () {
-      this.testRoom.leave(this)
-      return super.disconnect()
-    }
-    reconnect () {
-      this.testRoom.join(this)
-      return super.reconnect()
-    }
-    send (uid, message) {
-      this.testRoom.send(this.userId, uid, message)
-    }
-    broadcast (message) {
-      this.testRoom.broadcast(this.userId, message)
-    }
-    async whenSynced (f) {
-      var synced = false
-      var periodicFlushTillSync = () => {
-        if (synced) {
-          f()
-        } else {
-          this.testRoom.flushAll([this.y]).then(function () {
-            setTimeout(periodicFlushTillSync, 10)
-          })
-        }
-      }
-      periodicFlushTillSync()
-      return super.whenSynced(function () {
-        synced = true
-      })
-    }
-    receiveMessage (sender, m) {
-      if (this.userId !== sender && this.connections[sender] != null) {
-        var buffer = this.connections[sender].buffer
-        if (buffer == null) {
-          buffer = this.connections[sender].buffer = []
-        }
-        buffer.push(m)
-        if (this.chance.bool({likelihood: 30})) {
-          // flush 1/2 with 30% chance
-          var flushLength = Math.round(buffer.length / 2)
-          buffer.splice(0, flushLength).forEach(m => {
-            super.receiveMessage(sender, m)
-          })
-        }
-      }
-    }
-    async _flushAll (flushUsers) {
-      if (flushUsers.some(u => u.connector.userId === this.userId)) {
-        // this one needs to sync with every other user
-        flushUsers = Object.keys(this.connections).map(id => this.testRoom.users[id].y)
-      }
-      var finished = []
-      for (let i = 0; i < flushUsers.length; i++) {
-        let userId = flushUsers[i].connector.userId
-        if (userId !== this.userId && this.connections[userId] != null) {
-          let buffer = this.connections[userId].buffer
-          if (buffer != null) {
-            var messages = buffer.splice(0)
-            for (let j = 0; j < messages.length; j++) {
-              let p = super.receiveMessage(userId, messages[j])
-              finished.push(p)
-            }
-          }
-        }
-      }
-      await Promise.all(finished)
-      await this.y.db.whenTransactionsFinished()
-      return finished.length > 0 ? 'flushing' : 'done'
-    }
-  }
-  Y.extend('test', TestConnector)
-}
-
-if (typeof Y !== 'undefined') {
-  extendTestConnector(Y)
-}

tests/doc.tests.js

@@ -0,0 +1,126 @@
+
+import * as Y from '../src/index.js'
+import * as t from 'lib0/testing'
+
+/**
+ * Client id should be changed when an instance receives updates from another client using the same client id.
+ *
+ * @param {t.TestCase} tc
+ */
+export const testClientIdDuplicateChange = tc => {
+  const doc1 = new Y.Doc()
+  doc1.clientID = 0
+  const doc2 = new Y.Doc()
+  doc2.clientID = 0
+  t.assert(doc2.clientID === doc1.clientID)
+  doc1.getArray('a').insert(0, [1, 2])
+  Y.applyUpdate(doc2, Y.encodeStateAsUpdate(doc1))
+  t.assert(doc2.clientID !== doc1.clientID)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testGetTypeEmptyId = tc => {
+  const doc1 = new Y.Doc()
+  doc1.getText('').insert(0, 'h')
+  doc1.getText().insert(1, 'i')
+  const doc2 = new Y.Doc()
+  Y.applyUpdate(doc2, Y.encodeStateAsUpdate(doc1))
+  t.assert(doc2.getText().toString() === 'hi')
+  t.assert(doc2.getText('').toString() === 'hi')
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testToJSON = tc => {
+  const doc = new Y.Doc()
+  t.compare(doc.toJSON(), {}, 'doc.toJSON yields empty object')
+
+  const arr = doc.getArray('array')
+  arr.push(['test1'])
+
+  const map = doc.getMap('map')
+  map.set('k1', 'v1')
+  const map2 = new Y.Map()
+  map.set('k2', map2)
+  map2.set('m2k1', 'm2v1')
+
+  t.compare(doc.toJSON(), {
+    array: ['test1'],
+    map: {
+      k1: 'v1',
+      k2: {
+        m2k1: 'm2v1'
+      }
+    }
+  }, 'doc.toJSON has array and recursive map')
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testSubdoc = tc => {
+  const doc = new Y.Doc()
+  doc.load() // doesn't do anything
+  {
+    /**
+     * @type {Array<any>|null}
+     */
+    let event = /** @type {any} */ (null)
+    doc.on('subdocs', subdocs => {
+      event = [Array.from(subdocs.added).map(x => x.guid), Array.from(subdocs.removed).map(x => x.guid), Array.from(subdocs.loaded).map(x => x.guid)]
+    })
+    const subdocs = doc.getMap('mysubdocs')
+    const docA = new Y.Doc({ guid: 'a' })
+    docA.load()
+    subdocs.set('a', docA)
+    t.compare(event, [['a'], [], ['a']])
+
+    event = null
+    subdocs.get('a').load()
+    t.assert(event === null)
+
+    event = null
+    subdocs.get('a').destroy()
+    t.compare(event, [['a'], ['a'], []])
+    subdocs.get('a').load()
+    t.compare(event, [[], [], ['a']])
+
+    subdocs.set('b', new Y.Doc({ guid: 'a' }))
+    t.compare(event, [['a'], [], []])
+    subdocs.get('b').load()
+    t.compare(event, [[], [], ['a']])
+
+    const docC = new Y.Doc({ guid: 'c' })
+    docC.load()
+    subdocs.set('c', docC)
+    t.compare(event, [['c'], [], ['c']])
+
+    t.compare(Array.from(doc.getSubdocGuids()), ['a', 'c'])
+  }
+
+  const doc2 = new Y.Doc()
+  {
+    t.compare(Array.from(doc2.getSubdocs()), [])
+    /**
+     * @type {Array<any>|null}
+     */
+    let event = /** @type {any} */ (null)
+    doc2.on('subdocs', subdocs => {
+      event = [Array.from(subdocs.added).map(d => d.guid), Array.from(subdocs.removed).map(d => d.guid), Array.from(subdocs.loaded).map(d => d.guid)]
+    })
+    Y.applyUpdate(doc2, Y.encodeStateAsUpdate(doc))
+    t.compare(event, [['a', 'a', 'c'], [], []])
+
+    doc2.getMap('mysubdocs').get('a').load()
+    t.compare(event, [[], [], ['a']])
+
+    t.compare(Array.from(doc2.getSubdocGuids()), ['a', 'c'])
+
+    doc2.getMap('mysubdocs').delete('a')
+    t.compare(event, [[], ['a'], []])
+    t.compare(Array.from(doc2.getSubdocGuids()), ['a', 'c'])
+  }
+}

tests/encoding.tests.js

@@ -0,0 +1,108 @@
+import * as t from 'lib0/testing'
+import * as promise from 'lib0/promise'
+
+import {
+  contentRefs,
+  readContentBinary,
+  readContentDeleted,
+  readContentString,
+  readContentJSON,
+  readContentEmbed,
+  readContentType,
+  readContentFormat,
+  readContentAny,
+  readContentDoc,
+  Doc,
+  PermanentUserData,
+  encodeStateAsUpdate,
+  applyUpdate
+} from '../src/internals.js'
+
+import * as Y from '../src/index.js'
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testStructReferences = tc => {
+  t.assert(contentRefs.length === 11)
+  t.assert(contentRefs[1] === readContentDeleted)
+  t.assert(contentRefs[2] === readContentJSON) // TODO: deprecate content json?
+  t.assert(contentRefs[3] === readContentBinary)
+  t.assert(contentRefs[4] === readContentString)
+  t.assert(contentRefs[5] === readContentEmbed)
+  t.assert(contentRefs[6] === readContentFormat)
+  t.assert(contentRefs[7] === readContentType)
+  t.assert(contentRefs[8] === readContentAny)
+  t.assert(contentRefs[9] === readContentDoc)
+  // contentRefs[10] is reserved for Skip structs
+}
+
+/**
+ * There is some custom encoding/decoding happening in PermanentUserData.
+ * This is why it landed here.
+ *
+ * @param {t.TestCase} tc
+ */
+export const testPermanentUserData = async tc => {
+  const ydoc1 = new Doc()
+  const ydoc2 = new Doc()
+  const pd1 = new PermanentUserData(ydoc1)
+  const pd2 = new PermanentUserData(ydoc2)
+  pd1.setUserMapping(ydoc1, ydoc1.clientID, 'user a')
+  pd2.setUserMapping(ydoc2, ydoc2.clientID, 'user b')
+  ydoc1.getText().insert(0, 'xhi')
+  ydoc1.getText().delete(0, 1)
+  ydoc2.getText().insert(0, 'hxxi')
+  ydoc2.getText().delete(1, 2)
+  await promise.wait(10)
+  applyUpdate(ydoc2, encodeStateAsUpdate(ydoc1))
+  applyUpdate(ydoc1, encodeStateAsUpdate(ydoc2))
+
+  // now sync a third doc with same name as doc1 and then create PermanentUserData
+  const ydoc3 = new Doc()
+  applyUpdate(ydoc3, encodeStateAsUpdate(ydoc1))
+  const pd3 = new PermanentUserData(ydoc3)
+  pd3.setUserMapping(ydoc3, ydoc3.clientID, 'user a')
+}
+
+/**
+ * Reported here: https://github.com/yjs/yjs/issues/308
+ * @param {t.TestCase} tc
+ */
+export const testDiffStateVectorOfUpdateIsEmpty = tc => {
+  const ydoc = new Y.Doc()
+  /**
+   * @type {null | Uint8Array}
+   */
+  let sv = /* any */ (null)
+  ydoc.getText().insert(0, 'a')
+  ydoc.on('update', update => {
+    sv = Y.encodeStateVectorFromUpdate(update)
+  })
+  // should produce an update with an empty state vector (because previous ops are missing)
+  ydoc.getText().insert(0, 'a')
+  t.assert(sv !== null && sv.byteLength === 1 && sv[0] === 0)
+}
+
+/**
+ * Reported here: https://github.com/yjs/yjs/issues/308
+ * @param {t.TestCase} tc
+ */
+export const testDiffStateVectorOfUpdateIgnoresSkips = tc => {
+  const ydoc = new Y.Doc()
+  /**
+   * @type {Array<Uint8Array>}
+   */
+  const updates = []
+  ydoc.on('update', update => {
+    updates.push(update)
+  })
+  ydoc.getText().insert(0, 'a')
+  ydoc.getText().insert(0, 'b')
+  ydoc.getText().insert(0, 'c')
+  const update13 = Y.mergeUpdates([updates[0], updates[2]])
+  const sv = Y.encodeStateVectorFromUpdate(update13)
+  const state = Y.decodeStateVector(sv)
+  t.assert(state.get(ydoc.clientID) === 1)
+  t.assert(state.size === 1)
+}

tests/index.js

@@ -0,0 +1,28 @@
+
+import * as map from './y-map.tests.js'
+import * as array from './y-array.tests.js'
+import * as text from './y-text.tests.js'
+import * as xml from './y-xml.tests.js'
+import * as encoding from './encoding.tests.js'
+import * as undoredo from './undo-redo.tests.js'
+import * as compatibility from './compatibility.tests.js'
+import * as doc from './doc.tests.js'
+import * as snapshot from './snapshot.tests.js'
+import * as updates from './updates.tests.js'
+import * as relativePositions from './relativePositions.tests.js'
+
+import { runTests } from 'lib0/testing'
+import { isBrowser, isNode } from 'lib0/environment'
+import * as log from 'lib0/logging'
+
+if (isBrowser) {
+  log.createVConsole(document.body)
+}
+runTests({
+  doc, map, array, text, xml, encoding, undoredo, compatibility, snapshot, updates, relativePositions
+}).then(success => {
+  /* istanbul ignore next */
+  if (isNode) {
+    process.exit(success ? 0 : 1)
+  }
+})

tests/relativePositions.tests.js

@@ -0,0 +1,104 @@
+
+import * as Y from '../src/index.js'
+import * as t from 'lib0/testing'
+
+/**
+ * @param {Y.Text} ytext
+ */
+const checkRelativePositions = ytext => {
+  // test if all positions are encoded and restored correctly
+  for (let i = 0; i < ytext.length; i++) {
+    // for all types of associations..
+    for (let assoc = -1; assoc < 2; assoc++) {
+      const rpos = Y.createRelativePositionFromTypeIndex(ytext, i, assoc)
+      const encodedRpos = Y.encodeRelativePosition(rpos)
+      const decodedRpos = Y.decodeRelativePosition(encodedRpos)
+      const absPos = /** @type {Y.AbsolutePosition} */ (Y.createAbsolutePositionFromRelativePosition(decodedRpos, /** @type {Y.Doc} */ (ytext.doc)))
+      t.assert(absPos.index === i)
+      t.assert(absPos.assoc === assoc)
+    }
+  }
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase1 = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  ytext.insert(0, '1')
+  ytext.insert(0, 'abc')
+  ytext.insert(0, 'z')
+  ytext.insert(0, 'y')
+  ytext.insert(0, 'x')
+  checkRelativePositions(ytext)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase2 = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  ytext.insert(0, 'abc')
+  checkRelativePositions(ytext)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase3 = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  ytext.insert(0, 'abc')
+  ytext.insert(0, '1')
+  ytext.insert(0, 'xyz')
+  checkRelativePositions(ytext)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase4 = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  ytext.insert(0, '1')
+  checkRelativePositions(ytext)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase5 = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  ytext.insert(0, '2')
+  ytext.insert(0, '1')
+  checkRelativePositions(ytext)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionCase6 = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  checkRelativePositions(ytext)
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testRelativePositionAssociationDifference = tc => {
+  const ydoc = new Y.Doc()
+  const ytext = ydoc.getText()
+  ytext.insert(0, '2')
+  ytext.insert(0, '1')
+  const rposRight = Y.createRelativePositionFromTypeIndex(ytext, 1, 0)
+  const rposLeft = Y.createRelativePositionFromTypeIndex(ytext, 1, -1)
+  ytext.insert(1, 'x')
+  const posRight = Y.createAbsolutePositionFromRelativePosition(rposRight, ydoc)
+  const posLeft = Y.createAbsolutePositionFromRelativePosition(rposLeft, ydoc)
+  t.assert(posRight != null && posRight.index === 2)
+  t.assert(posLeft != null && posLeft.index === 1)
+}