make moved a separate prop on item

src/structs/ContentMove.js

@@ -0,0 +1,237 @@
+
+import * as error from 'lib0/error'
+import * as decoding from 'lib0/decoding'
+import {
+  AbstractType, ContentType, ID, RelativePosition, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Transaction, Item, StructStore, getItem, getItemCleanStart, getItemCleanEnd // eslint-disable-line
+} from '../internals.js'
+
+/**
+ * @param {ContentMove} moved
+ * @param {Transaction} tr
+ * @return {{ start: Item | null, end: Item | null }} $start (inclusive) is the beginning and $end (exclusive) is the end of the moved area
+ */
+export const getMovedCoords = (moved, tr) => {
+  let start // this (inclusive) is the beginning of the moved area
+  let end // this (exclusive) is the first item after start that is not part of the moved area
+  if (moved.start.item) {
+    if (moved.start.assoc < 0) {
+      start = getItemCleanEnd(tr, moved.start.item)
+      start = start.right
+    } else {
+      start = getItemCleanStart(tr, moved.start.item)
+    }
+  } else if (moved.start.tname != null) {
+    start = tr.doc.get(moved.start.tname)._start
+  } else if (moved.start.type) {
+    start = /** @type {ContentType} */ (getItem(tr.doc.store, moved.start.type).content).type._start
+  } else {
+    error.unexpectedCase()
+  }
+  if (moved.end.item) {
+    if (moved.end.assoc < 0) {
+      end = getItemCleanEnd(tr, moved.end.item)
+      end = end.right
+    } else {
+      end = getItemCleanStart(tr, moved.end.item)
+    }
+  } else {
+    end = null
+  }
+  return { start, end }
+}
+
+/**
+ * @param {ContentMove} moved
+ * @param {Item} movedItem
+ * @param {Transaction} tr
+ * @param {function(Item):void} cb
+ */
+export const iterateMoved = (moved, movedItem, tr, cb) => {
+  let { start, end } = getMovedCoords(moved, tr)
+  while (start !== end && start != null) {
+    if (!start.deleted) {
+      if (start.moved === movedItem) {
+        if (start.content.constructor === ContentMove) {
+          iterateMoved(start.content, start, tr, cb)
+        } else {
+          cb(start)
+        }
+      }
+    }
+    start = start.right
+  }
+}
+
+/**
+ * @param {ContentMove} moved
+ * @param {Item} movedItem
+ * @param {Set<Item>} trackedMovedItems
+ * @param {Transaction} tr
+ * @return {boolean} true if there is a loop
+ */
+export const findMoveLoop = (moved, movedItem, trackedMovedItems, tr) => {
+  if (trackedMovedItems.has(movedItem)) {
+    return true
+  }
+  trackedMovedItems.add(movedItem)
+  let { start, end } = getMovedCoords(moved, tr)
+  while (start !== end && start != null) {
+    if (start.deleted && start.moved === movedItem && start.content.constructor === ContentMove) {
+      if (findMoveLoop(start.content, start, trackedMovedItems, tr)) {
+        return true
+      }
+    }
+    start = start.right
+  }
+  return false
+}
+
+/**
+ * @private
+ */
+export class ContentMove {
+  /**
+   * @param {RelativePosition} start
+   * @param {RelativePosition} end
+   * @param {number} priority if we want to move content that is already moved, we need to assign a higher priority to this move operation.
+   */
+  constructor (start, end, priority) {
+    this.start = start
+    this.end = end
+    this.priority = priority
+    /**
+     * We store which Items+ContentMove we override. Once we delete
+     * this ContentMove, we need to re-integrate the overridden items.
+     *
+     * This representation can be improved if we ever run into memory issues because of too many overrides.
+     * Ideally, we should probably just re-iterate the document and re-integrate all moved items.
+     * This is fast enough and reduces memory footprint significantly.
+     *
+     * @type {Set<Item>}
+     */
+    this.overrides = new Set()
+  }
+
+  /**
+   * @return {number}
+   */
+  getLength () {
+    return 1
+  }
+
+  /**
+   * @return {Array<any>}
+   */
+  getContent () {
+    return [null]
+  }
+
+  /**
+   * @return {boolean}
+   */
+  isCountable () {
+    return false
+  }
+
+  /**
+   * @return {ContentMove}
+   */
+  copy () {
+    return new ContentMove(this.start, this.end, this.priority)
+  }
+
+  /**
+   * @param {number} offset
+   * @return {ContentMove}
+   */
+  splice (offset) {
+    return this
+  }
+
+  /**
+   * @param {ContentMove} right
+   * @return {boolean}
+   */
+  mergeWith (right) {
+    return false
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  integrate (transaction, item) {
+    /** @type {AbstractType<any>} */ (item.parent)._searchMarker = []
+    let { start, end } = getMovedCoords(this, transaction)
+    while (start !== end && start != null) {
+      if (!start.deleted) {
+        const currMoved = start.moved
+        if (currMoved === null || /** @type {ContentMove} */ (currMoved.content).priority < this.priority || currMoved.id.client < item.id.client || (currMoved.id.client === item.id.client && currMoved.id.clock < item.id.clock)) {
+          if (currMoved !== null) {
+            this.overrides.add(currMoved)
+          }
+          start.moved = item
+        } else {
+          /** @type {ContentMove} */ (currMoved.content).overrides.add(item)
+        }
+      }
+      start = start.right
+    }
+  }
+
+  /**
+   * @param {Transaction} transaction
+   * @param {Item} item
+   */
+  delete (transaction, item) {
+    let { start, end } = getMovedCoords(this, transaction)
+    while (start !== end && start != null) {
+      if (start.moved === item) {
+        start.moved = null
+      }
+      start = start.right
+    }
+    /**
+     * @param {Item} reIntegrateItem
+     */
+    const reIntegrate = reIntegrateItem => {
+      const content = /** @type {ContentMove} */ (reIntegrateItem.content)
+      if (reIntegrateItem.deleted) {
+        // potentially we can integrate the items that reIntegrateItem overrides
+        content.overrides.forEach(reIntegrate)
+      } else {
+        content.integrate(transaction, reIntegrateItem)
+      }
+    }
+    this.overrides.forEach(reIntegrate)
+  }
+
+  /**
+   * @param {StructStore} store
+   */
+  gc (store) {}
+
+  /**
+   * @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
+   * @param {number} offset
+   */
+  write (encoder, offset) {
+    encoder.writeAny(this.start)
+    encoder.writeAny(this.end)
+  }
+
+  /**
+   * @return {number}
+   */
+  getRef () {
+    return 11
+  }
+}
+
+/**
+ * @private
+ *
+ * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
+ * @return {ContentMove}
+ */
+export const readContentMove = decoder => new ContentMove(decoder.readAny(), decoder.readAny(), decoding.readVarUint(decoder.restDecoder))

src/structs/Item.js

@@ -282,14 +282,18 @@ export class Item extends AbstractStruct {
      */
     this.parentSub = parentSub
     /**
-     * If this type is deleted: If this type's effect is reundone this type refers to the type-id that undid
+     * If this type's effect is reundone this type refers to the type-id that undid
      * this operation.
      *
-     * If this item is not deleted: This property is reused by the moved prop. In this case this property refers to an Item.
-     *
-     * @type {ID | Item | null}
+     * @type {ID | null}
      */
-    this._ref = null
+    this.redone = null
+    /**
+     * This property is reused by the moved prop. In this case this property refers to an Item.
+     *
+     * @type {Item | null}
+     */
+    this.moved = null
     /**
      * @type {AbstractContent}
      */
@@ -299,57 +303,11 @@ export class Item extends AbstractStruct {
      * bit2: countable
      * bit3: deleted
      * bit4: mark - mark node as fast-search-marker
-     * bit5: moved - whether this item has been moved. The moved item is then referred to on the "redone" prop.
      * @type {number} byte
      */
     this.info = this.content.isCountable() ? binary.BIT2 : 0
   }
 
-  /**
-   * If this type's effect is reundone this type refers to the type-id that undid
-   * this operation.
-   *
-   * @return {ID | null}
-   */
-  get redone () {
-    return /** @type {ID | null} */ (this._ref)
-  }
-
-  /**
-   * @param {ID | null} id
-   */
-  set redone (id) {
-    this._ref = id
-  }
-
-  /**
-   * If this item has been moved, the moved property will referr to the item that moved this content.
-   *
-   * @param {Item | null} item
-   */
-  set movedBy (item) {
-    this._ref = item
-    if (item != null) {
-      this.info |= binary.BIT5
-    } else if (this.moved) {
-      this.info ^= binary.BIT5
-    }
-  }
-
-  /**
-   * @return {Item | null}
-   */
-  get movedBy () {
-    return this.moved ? /** @type {Item} */ (this._ref) : null
-  }
-
-  /**
-   * @return {boolean}
-   */
-  get moved () {
-    return (this.info & binary.BIT5) > 0
-  }
-
   /**
    * This is used to mark the item as an indexed fast-search marker
    *
@@ -617,8 +575,9 @@ export class Item extends AbstractStruct {
       this.id.client === right.id.client &&
       this.id.clock + this.length === right.id.clock &&
       this.deleted === right.deleted &&
-      this._ref === right._ref &&
-      (!this.deleted || this.redone === null) &&
+      this.redone === null &&
+      right.redone === null &&
+      this.moved === right.moved &&
       this.content.constructor === right.content.constructor &&
       this.content.mergeWith(right.content)
     ) {

src/types/AbstractType.js

@@ -443,7 +443,7 @@ export class ListPosition {
       this.rel = 0
     }
     while (item && !this.reachedEnd && (len > 0 || (len === 0 && (!item.countable || item.deleted)))) {
-      if (item.countable && !item.deleted && item.movedBy === this.currMove) {
+      if (item.countable && !item.deleted && item.moved === this.currMove) {
         len -= item.length
         if (len <= 0) {
           this.rel = -len