SELECT element: Introduce light-weight OPTION iterater.

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

 /*
  * 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) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 13 matching lines @@
  */
 
 #ifndef HTMLSelectElement_h
 #define HTMLSelectElement_h
 
 #include "base/gtest_prod_util.h"
 #include "core/CoreExport.h"
 #include "core/html/HTMLContentElement.h"
 #include "core/html/HTMLFormControlElementWithState.h"
 #include "core/html/HTMLOptionsCollection.h"
+#include "core/html/forms/OptionList.h"
 #include "core/html/forms/TypeAhead.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class AutoscrollController;
 class ExceptionState;
 class HTMLHRElement;
 class HTMLOptGroupElement;
 class HTMLOptionElement;
@@ skipping 32 matching lines @@
     void add(const HTMLOptionElementOrHTMLOptGroupElement&, const HTMLElementOrLong&, ExceptionState&);
 
     using Node::remove;
     void remove(int index);
 
     String value() const;
     void setValue(const String&, bool sendEvents = false);
     String suggestedValue() const;
     void setSuggestedValue(const String&);
 
+    // |options| and |selectedOptions| are not safe to be used in in
+    // HTMLOptionElement::removedFrom() and insertedInto() because their cache
+    // is inconsistent in these functions.
     HTMLOptionsCollection* options();
     HTMLCollection* selectedOptions();
 
+    // This is similar to |options| HTMLCollection.  But this is safe in
+    // HTMLOptionElement::removedFrom() and insertedInto().
+    // OptionList supports only forward iteration.
+    OptionList optionList() { return OptionList(*this); }
+
     void optionElementChildrenChanged(const HTMLOptionElement&);
 
     void invalidateSelectedItems();
 
     using ListItems = HeapVector<Member<HTMLElement>>;
+    // We prefer |optionList()| to |listItems()|.
     const ListItems& listItems() const;
 
     void accessKeyAction(bool sendMouseEvents) override;
     void accessKeySetSelectedIndex(int);
 
     void setOption(unsigned index, HTMLOptionElement*, ExceptionState&);
 
     Element* namedItem(const AtomicString& name);
     HTMLOptionElement* item(unsigned index);
 
@@ skipping 183 matching lines @@
 
     FRIEND_TEST_ALL_PREFIXES(HTMLSelectElementTest, FirstSelectableOption);
     FRIEND_TEST_ALL_PREFIXES(HTMLSelectElementTest, LastSelectableOption);
     FRIEND_TEST_ALL_PREFIXES(HTMLSelectElementTest, NextSelectableOption);
     FRIEND_TEST_ALL_PREFIXES(HTMLSelectElementTest, PreviousSelectableOption);
 };
 
 } // namespace blink
 
 #endif // HTMLSelectElement_h