handle nested moves

src/structs/ContentMove.js

@@ -2,8 +2,9 @@
 import * as error from 'lib0/error'
 import * as decoding from 'lib0/decoding'
 import * as encoding from 'lib0/encoding'
+import * as math from 'lib0/math'
 import {
-  AbstractType, ContentType, ID, RelativePosition, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Transaction, Item, StructStore, getItem, getItemCleanStart, getItemCleanEnd // eslint-disable-line
+  AbstractType, ContentType, RelativePosition, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Transaction, Item, StructStore, getItem, getItemCleanStart, getItemCleanEnd // eslint-disable-line
 } from '../internals.js'
 
 /**
@@ -175,13 +176,24 @@ export class ContentMove {
      * @type {{ start: Item | null, end: Item | null }}
      */
     let { start, end } = getMovedCoords(this, transaction)
+    let maxPriority = 0
+    // If this ContentMove was created locally, we set prio = -1. This indicates
+    // that we want to set prio to the current prio-maximum of the moved range.
+    const adaptPriority = this.priority < 0
     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)) {
+        const nextPrio = currMoved ? /** @type {ContentMove} */ (currMoved.content).priority : -1
+        if (currMoved === null || adaptPriority || nextPrio < 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)
           }
+          maxPriority = math.max(maxPriority, nextPrio)
+          // was already moved
+          if (start.moved && !transaction.prevMoved.has(start)) {
+            // we need to know which item previously moved an item
+            transaction.prevMoved.set(start, start.moved)
+          }
           start.moved = item
         } else {
           /** @type {ContentMove} */ (currMoved.content).overrides.add(item)
@@ -189,6 +201,9 @@ export class ContentMove {
       }
       start = start.right
     }
+    if (adaptPriority) {
+      this.priority = maxPriority + 1
+    }
   }
 
   /**
@@ -246,6 +261,7 @@ export class ContentMove {
 
 /**
  * @private
+ * @todo use binary encoding option for start & end relpos's
  *
  * @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
  * @return {ContentMove}

src/structs/Item.js

@@ -117,6 +117,12 @@ export const splitItem = (transaction, leftItem, diff) => {
     /** @type {AbstractType<any>} */ (rightItem.parent)._map.set(rightItem.parentSub, rightItem)
   }
   leftItem.length = diff
+  if (leftItem.moved) {
+    const m = transaction.prevMoved.get(leftItem)
+    if (m) {
+      transaction.prevMoved.set(rightItem, m)
+    }
+  }
   return rightItem
 }
 

src/types/YArray.js

@@ -149,9 +149,9 @@ export class YArray extends AbstractType {
     }
     if (this.doc !== null) {
       transact(this.doc, transaction => {
+        const left = createRelativePositionFromTypeIndex(this, start, assocStart)
+        const right = createRelativePositionFromTypeIndex(this, end + 1, assocEnd)
         useSearchMarker(transaction, this, target, walker => {
-          const left = createRelativePositionFromTypeIndex(this, start, assocStart)
-          const right = createRelativePositionFromTypeIndex(this, end + 1, assocEnd)
           walker.insertMove(transaction, left, right)
         })
       })

src/utils/ListIterator.js

@@ -122,7 +122,7 @@ export class ListIterator {
       len += this.rel
       this.rel = 0
     }
-    while (item && !this.reachedEnd && (len > 0 || (len === 0 && (!item.countable || item.deleted || item === this.currMoveEnd)))) {
+    while (item && !this.reachedEnd && (len > 0 || (len === 0 && (!item.countable || item.deleted || item === this.currMoveEnd || item.moved !== this.currMove)))) {
       if (item.countable && !item.deleted && item.moved === this.currMove && len > 0) {
         len -= item.length
         if (len < 0) {
@@ -350,7 +350,7 @@ export class ListIterator {
    * @param {RelativePosition} end
    */
   insertMove (tr, start, end) {
-    this.insertContents(tr, [new ContentMove(start, end, 1)]) // @todo adjust priority
+    this.insertContents(tr, [new ContentMove(start, end, -1)]) // @todo adjust priority
     // @todo is there a better alrogirthm to update searchmarkers? We could simply remove the markers that are in the updated range.
     // Also note that searchmarkers are updated in insertContents as well.
     const sm = this.type._searchMarker

src/utils/RelativePosition.js

@@ -9,6 +9,8 @@ import {
   createID,
   ContentType,
   followRedone,
+  transact,
+  useSearchMarker,
   ID, Doc, AbstractType // eslint-disable-line
 } from '../internals.js'
 
@@ -161,7 +163,6 @@ export const createRelativePosition = (type, item, assoc) => {
  * @function
  */
 export const createRelativePositionFromTypeIndex = (type, index, assoc = 0) => {
-  let t = type._start
   if (assoc < 0) {
     // associated to the left character or the beginning of a type, increment index if possible.
     if (index === 0) {
@@ -169,21 +170,17 @@ export const createRelativePositionFromTypeIndex = (type, index, assoc = 0) => {
     }
     index--
   }
-  while (t !== null) {
-    if (!t.deleted && t.countable) {
-      if (t.length > index) {
-        // case 1: found position somewhere in the linked list
-        return createRelativePosition(type, createID(t.id.client, t.id.clock + index), assoc)
+  return transact(/** @type {Doc} */ (type.doc), tr =>
+    useSearchMarker(tr, type, index, walker => {
+      if (walker.reachedEnd) {
+        const item = assoc < 0 ? /** @type {Item} */ (walker.nextItem).lastId : null
+        return createRelativePosition(type, item, assoc)
+      } else {
+        const id = /** @type {Item} */ (walker.nextItem).id
+        return createRelativePosition(type, createID(id.client, id.clock + walker.rel), assoc)
       }
-      index -= t.length
-    }
-    if (t.right === null && assoc < 0) {
-      // left-associated position, return last available id
-      return createRelativePosition(type, t.lastId, assoc)
-    }
-    t = t.right
-  }
-  return createRelativePosition(type, null, assoc)
+    })
+  )
 }
 
 /**

src/utils/Transaction.js

@@ -114,6 +114,14 @@ export class Transaction {
      * @type {Set<Doc>}
      */
     this.subdocsLoaded = new Set()
+    /**
+     * We store the reference that last moved an item.
+     * This is needed to compute the delta when multiple ContentMove move
+     * the same item.
+     *
+     * @type {Map<Item, Item>}
+     */
+    this.prevMoved = new Map()
   }
 }
 

src/utils/YEvent.js

@@ -213,7 +213,7 @@ export class YEvent {
                 continue // do not move to item.right
               }
             } else if (item.moved !== currMove) {
-              if (!currMoveIsNew && item.countable && !this.adds(item)) {
+              if (!currMoveIsNew && item.countable && !this.adds(item) && (this.transaction.prevMoved.get(item) || null) === currMove) {
                 if (lastOp === null || lastOp.delete === undefined) {
                   packOp()
                   lastOp = { delete: 0 }

tests/y-array.tests.js

@@ -466,6 +466,9 @@ export const testMove = tc => {
   Y.applyUpdate(users[1], Y.encodeStateAsUpdate(users[0]))
   t.compare(array1.toArray(), [2, 1, 3])
   t.compare(event1.delta, [{ insert: [2, 1, 3] }])
+  array0.move(0, 0, 2)
+  t.compare(array0.toArray(), [1, 2, 3])
+  t.compare(event0.delta, [{ delete: 1 }, { retain: 1 }, { insert: [2] }])
   compare(users)
 }