snapshot of https://github.com/yjs/yjs.git @ 96c96e1fcb1ef6ce866d5264b3f97f7f77b11f64 (2026-09-15)

src/utils/delta-helpers.js

@@ -0,0 +1,32 @@
+import * as delta from 'lib0/delta'
+import { createInsertSetFromStructStore, createDeleteSetFromStructStore, diffIdSet, mergeIdSets } from './ids.js'
+import { createDiffRenderer } from './Renderer.js'
+import { computeModifiedFromItems } from '../ynode.js'
+
+/**
+ * @param {Doc} v1
+ * @param {Doc} v2
+ * @return {delta.DeltaBuilderAny}
+ */
+export const diffDocsToDelta = (v1, v2, { renderer = createDiffRenderer(v1, v2) } = {}) => {
+  const insertDiff = diffIdSet(createInsertSetFromStructStore(v2.store, false), createInsertSetFromStructStore(v1.store, false))
+  const deleteDiff = diffIdSet(createDeleteSetFromStructStore(v2.store), createDeleteSetFromStructStore(v1.store))
+  // don't render items that have been inserted and then deleted
+  const insertsOnly = diffIdSet(insertDiff, deleteDiff)
+  const itemsToRender = mergeIdSets([insertsOnly, deleteDiff])
+  /**
+   * @type {Map<YNode, Set<string|null>>}
+   */
+  const changedTypes = computeModifiedFromItems(v2.store, itemsToRender)
+  const d = delta.create()
+  v2.share.forEach((type, typename) => {
+    const typeConf = changedTypes.get(type)
+    if (typeConf) {
+      const shareDelta = type.toDelta({
+        renderer, itemsToRender, retainDeletes: true, modified: changedTypes, deep: true
+      })
+      d.modifyAttr(typename, shareDelta)
+    }
+  })
+  return d
+}