Fix a crash in DecorationSet.map when a node is lifted from multiple …

…parent

FIX: Fix a crash in `DecorationSet.map` that could occur with some kinds of lift
transformations.

See https://discuss.prosemirror.net/t/mapping-node-decorations-creates-rangeerror-when-deleting-text/4491

src/decoration.js

@@ -512,9 +512,10 @@ function mapChildren(oldChildren, newLocal, mapping, node, offset, oldOffset, op
   let shift = (oldStart, oldEnd, newStart, newEnd) => {
     for (let i = 0; i < children.length; i += 3) {
       let end = children[i + 1], dSize
-      if (end == -1 || oldStart > end + oldOffset) continue
-      if (oldEnd >= children[i] + oldOffset) {
-        children[i + 1] = -1
+      if (end < 0 || oldStart > end + oldOffset) continue
+      let start = children[i] + oldOffset
+      if (oldEnd >= start) {
+        children[i + 1] = oldStart <= start ? -2 : -1
       } else if (newStart >= offset && (dSize = (newEnd - newStart) - (oldEnd - oldStart))) {
         children[i] += dSize
         children[i + 1] += dSize
@@ -526,7 +527,12 @@ function mapChildren(oldChildren, newLocal, mapping, node, offset, oldOffset, op
   // Find the child nodes that still correspond to a single node,
   // recursively call mapInner on them and update their positions.
   let mustRebuild = false
-  for (let i = 0; i < children.length; i += 3) if (children[i + 1] == -1) { // Touched nodes
+  for (let i = 0; i < children.length; i += 3) if (children[i + 1] < 0) { // Touched nodes
+    if (children[i + 1] == -2) {
+      mustRebuild = true
+      children[i + 1] = -1
+      continue
+    }
     let from = mapping.map(oldChildren[i] + oldOffset), fromLocal = from - offset
     if (fromLocal < 0 || fromLocal >= node.content.size) {
       mustRebuild = true

test/test-decoration.js

@@ -1,7 +1,7 @@
 const ist = require("ist")
 const {schema, doc, p, h1, li, ul, blockquote} = require("prosemirror-test-builder")
-const {Transform, ReplaceAroundStep} = require("prosemirror-transform")
-const {Slice} = require("prosemirror-model")
+const {Transform, ReplaceAroundStep, liftTarget} = require("prosemirror-transform")
+const {Slice, NodeRange} = require("prosemirror-model")
 
 const {Decoration, DecorationSet} = require("..")
 
@@ -236,6 +236,17 @@ describe("DecorationSet", () => {
       ist(mapped.from, 4)
       ist(mapped.to, 6)
     })
+
+    it("can handle nodes moving up multiple levels", () => {
+      let d = doc(ul(li(p())))
+      let set = build(d, {node: true, from: 2, to: 4})
+      let range = new NodeRange(d.resolve(2), d.resolve(4), 2)
+      let tr = new Transform(d).lift(range, liftTarget(range))
+      let mapped = set.map(tr.mapping, tr.doc).find()
+      ist(mapped.length, 1)
+      ist(mapped[0].from, 0)
+      ist(mapped[0].to, 2)
+    })
   })
 
   describe("add", () => {