Y.Text snapshot support (toDelta)

src/index.js

@@ -37,6 +37,8 @@ export {
   compareIDs,
   getState,
   Snapshot,
+  createSnapshot,
+  createSnapshotFromDoc,
   findRootTypeKey,
   typeListToArraySnapshot,
   typeMapGetSnapshot,

src/types/YText.js

@@ -16,6 +16,7 @@ import {
   ContentEmbed,
   ContentFormat,
   ContentString,
+  splitSnapshotAffectedStructs,
   Doc, Item, Snapshot, StructStore, Transaction // eslint-disable-line
 } from '../internals.js'
 
@@ -723,6 +724,7 @@ export class YText extends AbstractType {
      */
     const ops = []
     const currentAttributes = new Map()
+    const doc = /** @type {Doc} */ (this.doc)
     let str = ''
     let n = this._start
     function packStr () {
@@ -748,42 +750,54 @@ export class YText extends AbstractType {
         str = ''
       }
     }
-    while (n !== null) {
-      if (isVisible(n, snapshot) || (prevSnapshot !== undefined && isVisible(n, prevSnapshot))) {
-        switch (n.content.constructor) {
-          case ContentString:
-            const cur = currentAttributes.get('ychange')
-            if (snapshot !== undefined && !isVisible(n, snapshot)) {
-              if (cur === undefined || cur.user !== n.id.client || cur.state !== 'removed') {
-                packStr()
-                currentAttributes.set('ychange', { user: n.id.client, state: 'removed' })
-              }
-            } else if (prevSnapshot !== undefined && !isVisible(n, prevSnapshot)) {
-              if (cur === undefined || cur.user !== n.id.client || cur.state !== 'added') {
-                packStr()
-                currentAttributes.set('ychange', { user: n.id.client, state: 'added' })
-              }
-            } else if (cur !== undefined) {
-              packStr()
-              currentAttributes.delete('ychange')
-            }
-            str += /** @type {ContentString} */ (n.content).str
-            break
-          case ContentEmbed:
-            packStr()
-            ops.push({
-              insert: /** @type {ContentEmbed} */ (n.content).embed
-            })
-            break
-          case ContentFormat:
-            packStr()
-            updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (n.content))
-            break
-        }
+    // snapshots are merged again after the transaction, so we need to keep the
+    // transalive until we are done
+    transact(doc, transaction => {
+      if (snapshot) {
+        splitSnapshotAffectedStructs(transaction, snapshot)
       }
-      n = n.right
-    }
-    packStr()
+      if (prevSnapshot) {
+        splitSnapshotAffectedStructs(transaction, prevSnapshot)
+      }
+      while (n !== null) {
+        if (isVisible(n, snapshot) || (prevSnapshot !== undefined && isVisible(n, prevSnapshot))) {
+          switch (n.content.constructor) {
+            case ContentString:
+              const cur = currentAttributes.get('ychange')
+              if (snapshot !== undefined && !isVisible(n, snapshot)) {
+                if (cur === undefined || cur.user !== n.id.client || cur.state !== 'removed') {
+                  packStr()
+                  currentAttributes.set('ychange', { user: n.id.client, state: 'removed' })
+                }
+              } else if (prevSnapshot !== undefined && !isVisible(n, prevSnapshot)) {
+                if (cur === undefined || cur.user !== n.id.client || cur.state !== 'added') {
+                  packStr()
+                  currentAttributes.set('ychange', { user: n.id.client, state: 'added' })
+                }
+              } else if (cur !== undefined) {
+                packStr()
+                currentAttributes.delete('ychange')
+              }
+              str += /** @type {ContentString} */ (n.content).str
+              break
+            case ContentEmbed:
+              packStr()
+              ops.push({
+                insert: /** @type {ContentEmbed} */ (n.content).embed
+              })
+              break
+            case ContentFormat:
+              if (isVisible(n, snapshot)) {
+                packStr()
+                updateCurrentAttributes(currentAttributes, /** @type {ContentFormat} */ (n.content))
+              }
+              break
+          }
+        }
+        n = n.right
+      }
+      packStr()
+    }, splitSnapshotAffectedStructs)
     return ops
   }
 

src/utils/Snapshot.js

@@ -1,9 +1,17 @@
 
 import {
   isDeleted,
-  DeleteSet, Item // eslint-disable-line
+  createDeleteSetFromStructStore,
+  getStateVector,
+  getItemCleanStart,
+  createID,
+  iterateDeletedStructs,
+  Transaction, Doc, DeleteSet, Item // eslint-disable-line
 } from '../internals.js'
 
+import * as map from 'lib0/map.js'
+import * as set from 'lib0/set.js'
+
 export class Snapshot {
   /**
    * @param {DeleteSet} ds
@@ -27,9 +35,16 @@ export class Snapshot {
 /**
  * @param {DeleteSet} ds
  * @param {Map<number,number>} sm
+ * @return {Snapshot}
  */
 export const createSnapshot = (ds, sm) => new Snapshot(ds, sm)
 
+/**
+ * @param {Doc} doc
+ * @return {Snapshot}
+ */
+export const createSnapshotFromDoc = doc => createSnapshot(createDeleteSetFromStructStore(doc.store), getStateVector(doc.store))
+
 /**
  * @param {Item} item
  * @param {Snapshot|undefined} snapshot
@@ -40,3 +55,20 @@ export const createSnapshot = (ds, sm) => new Snapshot(ds, sm)
 export const isVisible = (item, snapshot) => snapshot === undefined ? !item.deleted : (
   snapshot.sm.has(item.id.client) && (snapshot.sm.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.sm.forEach((clock, client) => {
+      getItemCleanStart(transaction, store, createID(client, clock))
+    })
+    iterateDeletedStructs(transaction, snapshot.ds, store, item => {})
+    meta.add(snapshot)
+  }
+}

src/utils/Transaction.js

@@ -90,6 +90,11 @@ export class Transaction {
      * @type {any}
      */
     this.origin = origin
+    /**
+     * Stores meta information on the transaction
+     * @type {Map<any,any>}
+     */
+    this.meta = new Map()
   }
 }
 

tests/y-text.tests.js

@@ -1,6 +1,6 @@
-import { init, compare } from './testHelper.js'
-
+import * as Y from './testHelper.js'
 import * as t from 'lib0/testing.js'
+const { init, compare } = Y
 
 /**
  * @param {t.TestCase} tc
@@ -87,3 +87,65 @@ export const testGetDeltaWithEmbeds = tc => {
     insert: {linebreak: 's'}
   }])
 }
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testSnapshot = tc => {
+  const { text0 } = init(tc, { users: 1 })
+  const doc0 = /** @type {Y.Doc} */ (text0.doc)
+  doc0.gc = false
+  text0.applyDelta([{
+    insert: 'abcd'
+  }])
+  const snapshot1 = Y.createSnapshotFromDoc(doc0)
+  text0.applyDelta([{
+    retain: 1
+  }, {
+    insert: 'x'
+  }, {
+    delete: 1
+  }])
+  const snapshot2 = Y.createSnapshotFromDoc(doc0)
+  text0.applyDelta([{
+    retain: 2
+  }, {
+    delete: 3
+  }, {
+    insert: 'x'
+  }, {
+    delete: 1
+  }])
+  const state1 = text0.toDelta(snapshot1)
+  t.compare(state1, [{ insert: 'abcd' }])
+  const state2 = text0.toDelta(snapshot2)
+  t.compare(state2, [{ insert: 'axcd' }])
+  const state2Diff = text0.toDelta(snapshot2, snapshot1)
+  // @ts-ignore Remove userid info
+  state2Diff.forEach(v => {
+    if (v.attributes && v.attributes.ychange) {
+      delete v.attributes.ychange.user
+    }
+  })
+  t.compare(state2Diff, [{insert: 'a'}, {insert: 'x', attributes: {ychange: { state: 'added' }}}, {insert: 'b', attributes: {ychange: { state: 'removed' }}}, { insert: 'cd' }])
+}
+
+/**
+ * @param {t.TestCase} tc
+ */
+export const testSnapshotDeleteAfter = tc => {
+  const { text0 } = init(tc, { users: 1 })
+  const doc0 = /** @type {Y.Doc} */ (text0.doc)
+  doc0.gc = false
+  text0.applyDelta([{
+    insert: 'abcd'
+  }])
+  const snapshot1 = Y.createSnapshotFromDoc(doc0)
+  text0.applyDelta([{
+    retain: 4
+  }, {
+    insert: 'e'
+  }])
+  const state1 = text0.toDelta(snapshot1)
+  t.compare(state1, [{ insert: 'abcd' }])
+}