Improve how DocumentMarkerController updates markers in response to text edits

third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp

Index: third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
diff --git a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
index 34506d1809171ca1ef41fdc04d995e252f4aa773..32abf9d8d5a5e3cbf05e521a1eefd3c3a0ca172d 100644
--- a/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
+++ b/third_party/WebKit/Source/core/editing/markers/DocumentMarkerController.cpp
@@ -177,11 +177,6 @@ static bool startsFurther(const Member<RenderedDocumentMarker>& lhv,
   return lhv->startOffset() < rhv->startOffset();
 }
 
-static bool startsAfter(const Member<RenderedDocumentMarker>& marker,
-                        size_t startOffset) {
-  return marker->startOffset() < startOffset;
-}
-
 static bool endsBefore(size_t startOffset,
                        const Member<RenderedDocumentMarker>& rhv) {
   return startOffset < rhv->endOffset();
@@ -309,10 +304,7 @@ void DocumentMarkerController::copyMarkers(Node* srcNode,
     return;
 
   bool docDirty = false;
-  for (size_t markerListIndex = 0;
-       markerListIndex < DocumentMarker::MarkerTypeIndexesCount;
-       ++markerListIndex) {
-    Member<MarkerList>& list = (*markers)[markerListIndex];
+  for (Member<MarkerList> list : *markers) {
     if (!list)
       continue;
 
@@ -736,47 +728,6 @@ void DocumentMarkerController::repaintMarkers(
   }
 }
 
-void DocumentMarkerController::shiftMarkers(Node* node,
-                                            unsigned startOffset,
-                                            int delta) {
-  if (!possiblyHasMarkers(DocumentMarker::AllMarkers()))
-    return;
-  DCHECK(!m_markers.isEmpty());
-
-  MarkerLists* markers = m_markers.at(node);
-  if (!markers)
-    return;
-
-  bool didShiftMarker = false;
-  for (size_t markerListIndex = 0;
-       markerListIndex < DocumentMarker::MarkerTypeIndexesCount;
-       ++markerListIndex) {
-    Member<MarkerList>& list = (*markers)[markerListIndex];
-    if (!list)
-      continue;
-    MarkerList::iterator startPos =
-        std::lower_bound(list->begin(), list->end(), startOffset, startsAfter);
-    for (MarkerList::iterator marker = startPos; marker != list->end();
-         ++marker) {
-#if DCHECK_IS_ON()
-      int startOffset = (*marker)->startOffset();
-      DCHECK_GE(startOffset + delta, 0);
-#endif
-      (*marker)->shiftOffsets(delta);
-      didShiftMarker = true;
-    }
-  }
-
-  if (didShiftMarker) {
-    invalidateRectsForMarkersInNode(*node);
-    // repaint the affected node
-    if (node->layoutObject()) {
-      node->layoutObject()->setShouldDoFullPaintInvalidation(
-          PaintInvalidationDocumentMarkerChange);
-    }
-  }
-}
-
 bool DocumentMarkerController::setMarkersActive(const EphemeralRange& range,
                                                 bool active) {
   if (!possiblyHasMarkers(DocumentMarker::AllMarkers()))
@@ -876,10 +827,52 @@ void DocumentMarkerController::didUpdateCharacterData(CharacterData* node,
                                                       unsigned offset,
                                                       unsigned oldLength,
                                                       unsigned newLength) {
-  // Shift markers as if we first remove the old text, then insert the new text
-  removeMarkers(node, offset, oldLength);
-  shiftMarkers(node, offset + oldLength, 0 - oldLength);
-  shiftMarkers(node, offset, newLength);
+  // If we're doing a pure remove operation, remove the markers in the range
+  // being removed (markers containing, but larger than, the range, will be
+  // split)
+  if (newLength == 0)
+    removeMarkers(node, offset, oldLength);
+
+  if (!possiblyHasMarkers(DocumentMarker::AllMarkers()))
+    return;
+  DCHECK(!m_markers.isEmpty());
+
+  MarkerLists* markers = m_markers.at(node);
+  if (!markers)
+    return;
+
+  bool didShiftMarker = false;
+  for (MarkerList* list : *markers) {
+    if (!list)
+      continue;
+
+    for (MarkerList::iterator it = list->begin(); it != list->end(); ++it) {
+      RenderedDocumentMarker& marker = **it;
+      DocumentMarker::ShiftMarkerResult result =
+          marker.getShiftedMarkerPosition(offset, oldLength, newLength);
+      if (result.shouldRemoveMarker) {
+        list->erase(it - list->begin());
+        --it;
+        didShiftMarker = true;
+        continue;
+      }
+
+      if (marker.startOffset() != result.newStartOffset ||
+          marker.endOffset() != result.newEndOffset) {
+        didShiftMarker = true;
+        marker.setStartOffset(result.newStartOffset);
+        marker.setEndOffset(result.newEndOffset);
+      }
+    }
+  }
+
+  if (!didShiftMarker)
+    return;
+  if (!node->layoutObject())
+    return;
+  invalidateRectsForMarkersInNode(*node);
+  // repaint the affected node
+  node->layoutObject()->setShouldDoFullPaintInvalidation();
 }
 
 }  // namespace blink