added utilities to make and recover snapshots

types/YMap.js

@@ -8,7 +8,7 @@ import { ItemJSON } from '../structs/ItemJSON.js'
 import * as stringify from '../utils/structStringify.js'
 import { YEvent } from '../utils/YEvent.js'
 import { ItemBinary } from '../structs/ItemBinary.js'
-import { isVisible } from '../utils/snapshot.js';
+import { isVisible } from '../utils/snapshot.js'
 
 /**
  * Event that describes the changes on a YMap.
@@ -82,11 +82,11 @@ export class YMap extends Type {
         }
       }
     } else {
-      for (let key in this._map) {
-        if (this.has(key, snapshot)) {
+      this._map.forEach((_, key) => {
+        if (YMap.prototype.has.call(this, key, snapshot)) {
           keys.push(key)
         }
-      }
+      })
     }
     return keys
   }

types/YText.js

@@ -572,11 +572,12 @@ export class YText extends YArray {
    * Returns the Delta representation of this YText type.
    *
    * @param {import('../protocols/history.js').HistorySnapshot} [snapshot]
+   * @param {import('../protocols/history.js').HistorySnapshot} [prevSnapshot]
    * @return {Delta} The Delta representation of this type.
    *
    * @public
    */
-  toDelta (snapshot) {
+  toDelta (snapshot, prevSnapshot) {
     let ops = []
     let currentAttributes = new Map()
     let str = ''
@@ -602,9 +603,24 @@ export class YText extends YArray {
       }
     }
     while (n !== null) {
-      if (isVisible(n, snapshot)) {
+      if (isVisible(n, snapshot) || (prevSnapshot !== undefined && isVisible(n, prevSnapshot))) {
         switch (n.constructor) {
           case ItemString:
+            const cur = currentAttributes.get('ychange')
+            if (snapshot !== undefined && !isVisible(n, snapshot)) {
+              if (cur === undefined || cur.user !== n._id.user || cur.state !== 'removed') {
+                packStr()
+                currentAttributes.set('ychange', { user: n._id.user, state: 'removed' })
+              }
+            } else if (prevSnapshot !== undefined && !isVisible(n, prevSnapshot)) {
+              if (cur === undefined || cur.user !== n._id.user || cur.state !== 'added') {
+                packStr()
+                currentAttributes.set('ychange', { user: n._id.user, state: 'added' })
+              }
+            } else if (cur !== undefined) {
+              packStr()
+              currentAttributes.delete('ychange')
+            }
             str += n._content
             break
           case ItemFormat:

types/YXmlElement.js

@@ -326,9 +326,9 @@ export class YXmlElement extends YXmlFragment {
         }
       }
     } else {
-      for (let key in this._map) {
-        return YMap.prototype.get.call(this, key, snapshot)
-      }
+      YMap.prototype.keys.call(this, snapshot).forEach(key => {
+        obj[key] = YMap.prototype.get.call(this, key, snapshot)
+      })
     }
     return obj
   }