Use tracked changes and comments from the snapshot (#26267)

GitOrigin-RevId: c2bf0c9c9a5ab4f8837b8712ca549119a31cf067
2026-11-15 06:33:55 +01:00 · 2025-09-05 08:05:56 +00:00
parent 19866f48a8
commit 2c1baa717d
21 changed files with 737 additions and 267 deletions
@@ -0,0 +1,77 @@
+import { TrackedChangeList } from 'overleaf-editor-core'
+import { EditorState } from '@codemirror/state'
+import { rangesState } from '@/features/source-editor/extensions/history-ot'
+
+export const trackedDeletesFromState = (state: EditorState) =>
+  new TrackedDeletes(state.field(rangesState).trackedChanges)
+
+type OffsetTable = { pos: number; map: (pos: number) => number }[]
+
+export class TrackedDeletes {
+  private offsets: {
+    toCM6: OffsetTable
+    toSnapshot: OffsetTable
+  }
+
+  constructor(trackedChanges: TrackedChangeList) {
+    this.offsets = {
+      toCM6: [{ pos: 0, map: pos => pos }],
+      toSnapshot: [{ pos: 0, map: pos => pos }],
+    }
+
+    // Offset of the snapshot pos relative to the CM6 pos
+    let offset = 0
+    for (const change of trackedChanges.asSorted()) {
+      if (change.tracking.type === 'delete') {
+        const deleteLength = change.range.length
+        const deletePos = change.range.pos
+        const oldOffset = offset
+        const newOffset = offset + deleteLength
+        this.offsets.toSnapshot.push({
+          pos: change.range.pos - offset + 1,
+          map: pos => pos + newOffset,
+        })
+        this.offsets.toCM6.push({
+          pos: change.range.pos,
+          map: () => deletePos - oldOffset,
+        })
+        this.offsets.toCM6.push({
+          pos: change.range.pos + deleteLength,
+          map: pos => pos - newOffset,
+        })
+        offset = newOffset
+      }
+    }
+  }
+
+  toCodeMirror(snapshotPos: number) {
+    return this.mapPos(snapshotPos, this.offsets.toCM6)
+  }
+
+  toSnapshot(cm6Pos: number) {
+    return this.mapPos(cm6Pos, this.offsets.toSnapshot)
+  }
+
+  mapPos(pos: number, offsets: OffsetTable) {
+    // Binary search for the offset at the last position before pos
+    let low = 0
+    let high = offsets.length - 1
+    while (low < high) {
+      const middle = Math.ceil((low + high) / 2)
+      const entry = offsets[middle]
+      if (entry.pos < pos) {
+        // This entry could be the right offset, but lower entries are too low
+        // Because we used Math.ceil(), middle is higher than low and the
+        // algorithm progresses.
+        low = middle
+      } else if (entry.pos > pos) {
+        // This entry is too high
+        high = middle - 1
+      } else {
+        // This is the right entry
+        return entry.map(pos)
+      }
+    }
+    return offsets[low].map(pos)
+  }
+}