restructuring the project

src/utils/Transaction.js

@@ -0,0 +1,69 @@
+/**
+ * @module utils
+ */
+
+import * as encoding from 'funlib/encoding.js'
+
+/**
+ * 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"
+ *
+ */
+export class Transaction {
+  constructor (y) {
+    /**
+     * @type {Y} The Yjs instance.
+     */
+    this.y = y
+    /**
+     * All new types that are added during a transaction.
+     * @type {Set<Item>}
+     */
+    this.newTypes = new Set()
+    /**
+     * 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<Type|Y,String>}
+     */
+    this.changedTypes = new Map()
+    // TODO: rename deletedTypes
+    /**
+     * Set of all deleted Types and Structs.
+     * @type {Set<Item>}
+     */
+    this.deletedStructs = new Set()
+    /**
+     * Saves the old state set of the Yjs instance. If a state was modified,
+     * the original value is saved here.
+     * @type {Map<Number,Number>}
+     */
+    this.beforeState = new Map()
+    /**
+     * Stores the events for the types that observe also child elements.
+     * It is mainly used by `observeDeep`.
+     * @type {Map<Type,Array<YEvent>>}
+     */
+    this.changedParentTypes = new Map()
+    this.encodedStructsLen = 0
+    this.encodedStructs = encoding.createEncoder()
+  }
+}