correctly handle gc with UndoManager and un-merge when syncing

src/Struct/Delete.js

@@ -7,7 +7,7 @@ import { logID } from '../MessageHandler/messageToString.js'
  * Delete all items in an ID-range
  * TODO: implement getItemCleanStartNode for better performance (only one lookup)
  */
-export function deleteItemRange (y, user, clock, range) {
+export function deleteItemRange (y, user, clock, range, gcChildren) {
   const createDelete = y.connector !== null && y.connector._forwardAppliedStructs
   let item = y.os.getItemCleanStart(new ID(user, clock))
   if (item !== null) {
@@ -24,7 +24,7 @@ export function deleteItemRange (y, user, clock, range) {
         const nodeVal = node.val
         if (!nodeVal._deleted) {
           nodeVal._splitAt(y, range)
-          nodeVal._delete(y, createDelete, true)
+          nodeVal._delete(y, createDelete, gcChildren)
         }
         const nodeLen = nodeVal._length
         range -= nodeLen
@@ -100,7 +100,7 @@ export default class Delete {
     if (!locallyCreated) {
       // from remote
       const id = this._targetID
-      deleteItemRange(y, id.user, id.clock, this._length)
+      deleteItemRange(y, id.user, id.clock, this._length, false)
     } else if (y.connector !== null) {
       // from local
       y.connector.broadcastStruct(this)

src/Struct/GC.js

@@ -36,7 +36,6 @@ export default class GC {
       n._length += next._length
       y.os.delete(next._id)
     }
-
     if (id.user !== RootFakeUserID) {
       if (y.connector !== null && (y.connector._forwardAppliedStructs || id.user === y.userID)) {
         y.connector.broadcastStruct(this)
@@ -85,4 +84,11 @@ export default class GC {
   _splitAt () {
     return this
   }
+
+  _clonePartial (diff) {
+    const gc = new GC()
+    gc._id = new ID(this._id.user, this._id.clock + diff)
+    gc._length = this._length - diff
+    return gc
+  }
 }

src/Struct/Item.js

@@ -1,6 +1,6 @@
 import { getStructReference } from '../Util/structReferences.js'
 import ID from '../Util/ID/ID.js'
-import { RootFakeUserID } from '../Util/ID/RootID.js'
+import { default as RootID, RootFakeUserID } from '../Util/ID/RootID.js'
 import Delete from './Delete.js'
 import { transactionTypeChanged } from '../Transaction.js'
 import GC from './GC.js'
@@ -486,7 +486,12 @@ export default class Item {
       const parentID = decoder.readID()
       // parent does not change, so we don't have to search for it again
       if (this._parent === null) {
-        const parent = y.os.get(parentID)
+        let parent
+        if (parentID.constructor === RootID) {
+          parent = y.os.get(parentID)
+        } else {
+          parent = y.os.getItem(parentID)
+        }
         if (parent === null) {
           missing.push(parentID)
         } else {

src/Struct/Type.js

@@ -214,7 +214,10 @@ export default class Type extends Item {
    * @param {boolean} createDelete Whether to propagate a message that this
    *                               Type was deleted.
    */
-  _delete (y, createDelete, gcChildren = true) {
+  _delete (y, createDelete, gcChildren) {
+    if (gcChildren === undefined) {
+      gcChildren = y._hasUndoManager === false
+    }
     super._delete(y, createDelete, gcChildren)
     y._transaction.changedTypes.delete(this)
     // delete map types