SELECT element: Introduce light-weight OPTION iterater.

third_party/WebKit/Source/core/html/forms/OptionList.h

Index: third_party/WebKit/Source/core/html/forms/OptionList.h
diff --git a/third_party/WebKit/Source/core/html/forms/OptionList.h b/third_party/WebKit/Source/core/html/forms/OptionList.h
new file mode 100644
index 0000000000000000000000000000000000000000..07a36cf7da558b34f7b15b39bf22eee866f290d2
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+++ b/third_party/WebKit/Source/core/html/forms/OptionList.h
@@ -0,0 +1,56 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef OptionList_h
+#define OptionList_h
+
+#include "core/CoreExport.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class HTMLSelectElement;
+class HTMLOptionElement;
+
+class CORE_EXPORT OptionListIterator final {
+    STACK_ALLOCATED();
+public:
+    explicit OptionListIterator(HTMLSelectElement* select) : m_select(select)
+    {
+        if (m_select)
+            advance(nullptr);
+    }
+    HTMLOptionElement* operator*() { return m_current; }
+    void operator++()
+    {
+        if (m_current)
+            advance(m_current);
+    }
+    bool operator==(const OptionListIterator& other) const { return m_current == other.m_current; }
+    bool operator!=(const OptionListIterator& other) const { return !(*this == other); }
+
+private:
+    void advance(HTMLOptionElement* current);
+
+    Member<HTMLSelectElement> m_select;
+    Member<HTMLOptionElement> m_current; // nullptr means we reached to the end.
+};
+
+// OptionList class is a lightweight version of HTMLOptionsCollection.
+class OptionList final {
+    STACK_ALLOCATED();
+public:
+    explicit OptionList(HTMLSelectElement& select) : m_select(select) {}
+    using Iterator = OptionListIterator;
+    Iterator begin() { return Iterator(m_select); }
+    Iterator end() { return Iterator(nullptr); }
+
+private:
+    Member<HTMLSelectElement> m_select;
+};
+
+} // namespace blink
+
+#endif
+