Dispose temporary and not-cached Range in DOMSelection

third_party/WebKit/Source/core/editing/DOMSelection.cpp

 /*
  * Copyright (C) 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 107 matching lines @@
 }
 
 static Position basePosition(const VisibleSelection& selection) {
   return selection.base().parentAnchoredEquivalent();
 }
 
 static Position extentPosition(const VisibleSelection& selection) {
   return selection.extent().parentAnchoredEquivalent();
 }
 
+class ScopedRange {

[yosin_UTC9, 2017/03/30 08:58:17]

Please introduce a function acts like primaryRangeOrNull() but returns
EphemeralRange, e.g.

Optinal<EphemeralRange> compurePrimaryEphemeralRange().

We don't want to introduce |ScopedRange| anywhere. We discussed introducing it
on Jun 2014 when
[1] was filed.


[1] http://crbug.com/388681 Avoid registering temporary Range object for
updating on the Document

+  STACK_ALLOCATED();
+
+ public:
+  ScopedRange(Range* range, bool dispose)
+      : m_range(range), m_dispose(dispose) {}
+  ~ScopedRange() {
+    if (m_dispose)
+      m_range->dispose();
+  }
+
+ private:
+  Member<Range> m_range;
+  bool m_dispose;
+};
+
 Node* DOMSelection::anchorNode() const {
   if (Range* range = primaryRangeOrNull()) {
+    ScopedRange scope(range, !isSelectionOfDocument());
     if (!frame() || isBaseFirstInSelection())
       return range->startContainer();
     return range->endContainer();
   }
   return nullptr;
 }
 
 unsigned DOMSelection::anchorOffset() const {
   if (Range* range = primaryRangeOrNull()) {
+    ScopedRange scope(range, !isSelectionOfDocument());
     if (!frame() || isBaseFirstInSelection())
       return range->startOffset();
     return range->endOffset();
   }
   return 0;
 }
 
 Node* DOMSelection::focusNode() const {
   if (Range* range = primaryRangeOrNull()) {
+    ScopedRange scope(range, !isSelectionOfDocument());
     if (!frame() || isBaseFirstInSelection())
       return range->endContainer();
     return range->startContainer();
   }
   return nullptr;
 }
 
 unsigned DOMSelection::focusOffset() const {
   if (Range* range = primaryRangeOrNull()) {
+    ScopedRange scope(range, !isSelectionOfDocument());
     if (!frame() || isBaseFirstInSelection())
       return range->endOffset();
     return range->startOffset();
   }
   return 0;
 }
 
 Node* DOMSelection::baseNode() const {
   if (!isAvailable())
     return 0;
@@ skipping 415 matching lines @@
 void DOMSelection::clearCachedRangeIfSelectionOfDocument() {
   if (!isSelectionOfDocument())
     return;
   frame()->selection().clearDocumentCachedRange();
 }
 
 void DOMSelection::removeRange(Range* range) {
   DCHECK(range);
   if (!isAvailable())
     return;
-  if (range == primaryRangeOrNull())
+  Range* originalRange = primaryRangeOrNull();
+  ScopedRange scope(originalRange, !isSelectionOfDocument());
+  if (range == originalRange)
     frame()->selection().clear();
 }
 
 void DOMSelection::removeAllRanges() {
   if (!isAvailable())
     return;
   frame()->selection().clear();
 }
 
 void DOMSelection::addRange(Range* newRange) {
@@ skipping 21 matching lines @@
     updateFrameSelection(SelectionInDOMTree::Builder()
                              .collapse(newRange->startPosition())
                              .extend(newRange->endPosition())
                              .build(),
                          newRange);
     return;
   }
 
   Range* originalRange = primaryRangeOrNull();
   DCHECK(originalRange);
+  ScopedRange scope(originalRange, !isSelectionOfDocument());
 
   if (originalRange->startContainer()->treeScope() !=
       newRange->startContainer()->treeScope()) {
     return;
   }
 
   if (originalRange->compareBoundaryPoints(Range::kStartToEnd, newRange,
                                            ASSERT_NO_EXCEPTION) < 0 ||
       newRange->compareBoundaryPoints(Range::kStartToEnd, originalRange,
                                       ASSERT_NO_EXCEPTION) < 0) {
@@ skipping 178 matching lines @@
     m_treeScope->document().addConsoleMessage(
         ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, message));
 }
 
 DEFINE_TRACE(DOMSelection) {
   visitor->trace(m_treeScope);
   ContextClient::trace(visitor);
 }
 
 }  // namespace blink