SELECT element: Improve performance of HTMLSelectElement::optionIndexToBeShown().

third_party/WebKit/Source/core/html/HTMLSelectElement.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
@@ skipping 1104 matching lines @@
 
     if (usesMenuList()) {
         if (shouldDispatchEvents) {
             dispatchInputEvent();
             dispatchFormControlChangeEvent();
         }
         if (LayoutObject* layoutObject = this->layoutObject()) {
             // Need to check usesMenuList() again because event handlers might
             // change the status.
             if (usesMenuList()) {
-                // didSetSelectedIndex() is O(N) because of optionToListIndex.
-                toLayoutMenuList(layoutObject)->didSetSelectedIndex(optionIndex);
+                // didSelectOption() is O(N) because of HTMLOptionElement::index().
+                toLayoutMenuList(layoutObject)->didSelectOption(element);
             }
         }
     }
 
     notifyFormStateChanged();
 }
 
 int HTMLSelectElement::optionToListIndex(int optionIndex) const
 {
     const ListItems& items = listItems();
@@ skipping 841 matching lines @@
     }
 }
 
 void HTMLSelectElement::setIndexToSelectOnCancel(int listIndex)
 {
     m_indexToSelectOnCancel = listIndex;
     if (layoutObject())
         layoutObject()->updateFromElement();
 }
 
-int HTMLSelectElement::optionIndexToBeShown() const
+HTMLOptionElement* HTMLSelectElement::optionToBeShown() const
 {
-    if (m_indexToSelectOnCancel >= 0)
-        return listToOptionIndex(m_indexToSelectOnCancel);
-    // TODO(tkent): HTMLOptionElement::index() is O(N). This function should
-    // return HTMLOptionElement*.
+    if (m_indexToSelectOnCancel >= 0 && static_cast<size_t>(m_indexToSelectOnCancel) < listItems().size() && isHTMLOptionElement(listItems()[m_indexToSelectOnCancel]))
+        return toHTMLOptionElement(listItems()[m_indexToSelectOnCancel]);
     if (m_suggestedOption)
-        return m_suggestedOption->index();
-    int optionIndex = m_lastOnChangeOption ? m_lastOnChangeOption->index() : -1;
-    DCHECK_EQ(optionIndex, selectedIndex());
-    return optionIndex;
+        return m_suggestedOption;
+    DCHECK_EQ(selectedOption(), m_lastOnChangeOption);
+    return m_lastOnChangeOption;
 }
 
 void HTMLSelectElement::valueChanged(unsigned listIndex)
 {
     // Check to ensure a page navigation has not occurred while the popup was
     // up.
     Document& doc = document();
     if (&doc != doc.frame()->document())
         return;
 
@@ skipping 135 matching lines @@
 }
 
 void HTMLSelectElement::didMutateSubtree()
 {
     DCHECK(popupIsVisible());
     DCHECK(m_popup);
     m_popup->updateFromElement(PopupMenu::ByDOMChange);
 }
 
 } // namespace blink