Make DOMSelection cache Range

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 157 matching lines @@
   if (selection.isNone())
     return "None";
   if (selection.isCaret())
     return "Caret";
   return "Range";
 }
 
 int DOMSelection::rangeCount() const {
   if (!isAvailable())
     return 0;
+  if (m_Range)
+    return 1;
   return frame()->selection().isNone() ? 0 : 1;
 }
 
 void DOMSelection::collapse(Node* node,
                             int offset,
                             ExceptionState& exceptionState) {
   if (!isAvailable())
     return;
 
   if (!node) {
@@ skipping 218 matching lines @@
 
   if (index < 0 || index >= rangeCount()) {
     exceptionState.throwDOMException(
         IndexSizeError, String::number(index) + " is not a valid index.");
     return nullptr;
   }
 
   // If you're hitting this, you've added broken multi-range selection support
   DCHECK_EQ(rangeCount(), 1);
 
+  if (m_Range)
+    return m_Range;
+
+  Range* newRange = createRangeFromSelectionEditor();
+  if (!areRangesEqual(newRange, m_Range))

[tkent, 2017/01/25 07:59:12]

m_Range is always nullptr. Is this code equivalent to

if (Range* newRange = createRangeFromSelectionEditor())
    m_range = newRange;

right?

[yoichio, 2017/01/27 08:33:04]

Right.

+    m_Range = newRange;
+
+  return m_Range;
+}
+
+Range* DOMSelection::createRangeFromSelectionEditor() {
   Position anchor = anchorPosition(visibleSelection());
   if (!anchor.anchorNode()->isInShadowTree())
     return frame()->selection().firstRange();
 
   Node* node = shadowAdjustedNode(anchor);
   if (!node)  // crbug.com/595100
     return nullptr;
   if (!visibleSelection().isBaseFirst())
     return Range::create(*anchor.document(), focusNode(), focusOffset(), node,
                          anchorOffset());
   return Range::create(*anchor.document(), node, anchorOffset(), focusNode(),
                        focusOffset());
 }
 
+void DOMSelection::markRangeDirty() {
+  m_Range = nullptr;
+}
+
 void DOMSelection::removeAllRanges() {
+  m_Range = nullptr;
   if (!isAvailable())
     return;
   frame()->selection().clear();
 }
 
 void DOMSelection::addRange(Range* newRange) {
   DCHECK(newRange);
 
   if (!isAvailable())
     return;
@@ skipping 15 matching lines @@
 
   // TODO(xiaochengh): The use of updateStyleAndLayoutIgnorePendingStylesheets
   // needs to be audited.  See http://crbug.com/590369 for more details.
   // In the long term, we should change FrameSelection::setSelection to take a
   // parameter that does not require clean layout, so that modifying selection
   // no longer performs synchronous layout by itself.
   frame()->document()->updateStyleAndLayoutIgnorePendingStylesheets();
 
   if (selection.isNone()) {
     selection.setSelectedRange(EphemeralRange(newRange), VP_DEFAULT_AFFINITY);
+    m_Range = newRange;
     return;
   }
 
   Range* originalRange = selection.firstRange();
 
   if (originalRange->startContainer()->document() !=
       newRange->startContainer()->document()) {
     addConsoleError(
         "The given range does not belong to the current selection's document.");
     return;
@@ skipping 27 matching lines @@
                      ? originalRange
                      : newRange;
   Range* end = originalRange->compareBoundaryPoints(Range::kEndToEnd, newRange,
                                                     ASSERT_NO_EXCEPTION) < 0
                    ? newRange
                    : originalRange;
   const EphemeralRange merged =
       EphemeralRange(start->startPosition(), end->endPosition());
   TextAffinity affinity = selection.selection().affinity();
   selection.setSelectedRange(merged, affinity);
+  m_Range = createRange(merged);
 }
 
 void DOMSelection::deleteFromDocument() {
   if (!isAvailable())
     return;
 
   FrameSelection& selection = frame()->selection();
 
   if (selection.isNone())
     return;
@@ skipping 139 matching lines @@
 }
 
 void DOMSelection::addConsoleError(const String& message) {
   if (m_treeScope)
     m_treeScope->document().addConsoleMessage(
         ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, message));
 }
 
 DEFINE_TRACE(DOMSelection) {
   visitor->trace(m_treeScope);
+  visitor->trace(m_Range);
   ContextClient::trace(visitor);
 }
 
 }  // namespace blink