Have HTMLCollection::item() return an Element as per specification

Source/core/html/CollectionIndexCache.h

 /*
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 18 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef CollectionIndexCache_h
 #define CollectionIndexCache_h
 
 #include "core/dom/Element.h"
 
 namespace WebCore {
 
-template <typename Collection>
+template <typename Collection, typename NodeType>
 class CollectionIndexCache {
 public:
     CollectionIndexCache();
 
     bool isEmpty(const Collection& collection)
     {
         if (isCachedNodeCountValid())
             return !cachedNodeCount();
         if (cachedNode())
             return false;
         return !nodeAt(collection, 0);
     }
     bool hasExactlyOneNode(const Collection& collection)
     {
         if (isCachedNodeCountValid())
             return cachedNodeCount() == 1;
         if (cachedNode())
             return !cachedNodeIndex() && !nodeAt(collection, 1);
         return nodeAt(collection, 0) && !nodeAt(collection, 1);
     }
 
     unsigned nodeCount(const Collection&);
-    Node* nodeAt(const Collection&, unsigned index);
+    NodeType* nodeAt(const Collection&, unsigned index);
 
     void invalidate();
 
-    ALWAYS_INLINE void setCachedNode(Node* node, unsigned index)
+    ALWAYS_INLINE void setCachedNode(NodeType* node, unsigned index)
     {
         ASSERT(node);
         m_currentNode = node;
         m_cachedNodeIndex = index;
     }
 
 private:
-    Node* nodeBeforeOrAfterCachedNode(const Collection&, unsigned index, const ContainerNode& root);
+    NodeType* nodeBeforeOrAfterCachedNode(const Collection&, unsigned index, const ContainerNode& root);
     bool isLastNodeCloserThanLastOrCachedNode(unsigned index) const;
     bool isFirstNodeCloserThanCachedNode(unsigned index) const;
 
-    ALWAYS_INLINE Node* cachedNode() const { return m_currentNode; }
+    ALWAYS_INLINE NodeType* cachedNode() const { return m_currentNode; }
     ALWAYS_INLINE unsigned cachedNodeIndex() const { ASSERT(cachedNode()); return m_cachedNodeIndex; }
 
     ALWAYS_INLINE bool isCachedNodeCountValid() const { return m_isLengthCacheValid; }
     ALWAYS_INLINE unsigned cachedNodeCount() const { return m_cachedNodeCount; }
     ALWAYS_INLINE void setCachedNodeCount(unsigned length)
     {
         m_cachedNodeCount = length;
         m_isLengthCacheValid = true;
     }
 
-    Node* m_currentNode;
+    NodeType* m_currentNode;
     unsigned m_cachedNodeCount;
     unsigned m_cachedNodeIndex;
     unsigned m_isLengthCacheValid : 1;
 };
 
-template <typename Collection>
-CollectionIndexCache<Collection>::CollectionIndexCache()
+template <typename Collection, typename NodeType>
+CollectionIndexCache<Collection, NodeType>::CollectionIndexCache()
     : m_currentNode(0)
     , m_cachedNodeCount(0)
     , m_cachedNodeIndex(0)
     , m_isLengthCacheValid(false)
 {
 }
 
-template <typename Collection>
-void CollectionIndexCache<Collection>::invalidate()
+template <typename Collection, typename NodeType>
+void CollectionIndexCache<Collection, NodeType>::invalidate()
 {
     m_currentNode = 0;
     m_isLengthCacheValid = false;
 }
 
-template <typename Collection>
-inline unsigned CollectionIndexCache<Collection>::nodeCount(const Collection& collection)
+template <typename Collection, typename NodeType>
+inline unsigned CollectionIndexCache<Collection, NodeType>::nodeCount(const Collection& collection)
 {
     if (isCachedNodeCountValid())
         return cachedNodeCount();
 
     nodeAt(collection, UINT_MAX);
     ASSERT(isCachedNodeCountValid());
 
     return cachedNodeCount();
 }
 
-template <typename Collection>
-inline Node* CollectionIndexCache<Collection>::nodeAt(const Collection& collection, unsigned index)
+template <typename Collection, typename NodeType>
+inline NodeType* CollectionIndexCache<Collection, NodeType>::nodeAt(const Collection& collection, unsigned index)
 {
     if (cachedNode() && cachedNodeIndex() == index)
         return cachedNode();
 
     if (isCachedNodeCountValid() && cachedNodeCount() <= index)
         return 0;
 
     ContainerNode& root = collection.rootNode();
     if (isCachedNodeCountValid() && collection.canTraverseBackward() && isLastNodeCloserThanLastOrCachedNode(index)) {
-        Node* lastNode = collection.itemBefore(0);
+        NodeType* lastNode = collection.itemBefore(0);
         ASSERT(lastNode);
         setCachedNode(lastNode, cachedNodeCount() - 1);
     } else if (!cachedNode() || isFirstNodeCloserThanCachedNode(index) || (!collection.canTraverseBackward() && index < cachedNodeIndex())) {
-        Node* firstNode = collection.traverseToFirstElement(root);
+        NodeType* firstNode = collection.traverseToFirstElement(root);
         if (!firstNode) {
             setCachedNodeCount(0);
             return 0;
         }
         setCachedNode(firstNode, 0);
         ASSERT(!cachedNodeIndex());
     }
 
     if (cachedNodeIndex() == index)
         return cachedNode();
 
     return nodeBeforeOrAfterCachedNode(collection, index, root);
 }
 
-template <typename Collection>
-inline Node* CollectionIndexCache<Collection>::nodeBeforeOrAfterCachedNode(const Collection& collection, unsigned index, const ContainerNode &root)
+template <typename Collection, typename NodeType>
+inline NodeType* CollectionIndexCache<Collection, NodeType>::nodeBeforeOrAfterCachedNode(const Collection& collection, unsigned index, const ContainerNode &root)
 {
     unsigned currentIndex = cachedNodeIndex();
-    Node* currentNode = cachedNode();
+    NodeType* currentNode = cachedNode();
     ASSERT(currentNode);
     ASSERT(currentIndex != index);
 
     if (index < cachedNodeIndex()) {
         ASSERT(collection.canTraverseBackward());
         while ((currentNode = collection.itemBefore(currentNode))) {
             ASSERT(currentIndex);
             currentIndex--;
             if (currentIndex == index) {
                 setCachedNode(currentNode, currentIndex);
                 return currentNode;
             }
         }
         ASSERT_NOT_REACHED();
         return 0;
     }
 
     currentNode = collection.traverseForwardToOffset(index, *currentNode, currentIndex, root);
     if (!currentNode) {
         // Did not find the node. On plus side, we now know the length.
         setCachedNodeCount(currentIndex + 1);
         return 0;
     }
     setCachedNode(currentNode, currentIndex);
     return currentNode;
 }
 
-template <typename Collection>
-ALWAYS_INLINE bool CollectionIndexCache<Collection>::isLastNodeCloserThanLastOrCachedNode(unsigned index) const
+template <typename Collection, typename NodeType>
+ALWAYS_INLINE bool CollectionIndexCache<Collection, NodeType>::isLastNodeCloserThanLastOrCachedNode(unsigned index) const
 {
     ASSERT(isCachedNodeCountValid());
     unsigned distanceFromLastNode = cachedNodeCount() - index;
     if (!cachedNode())
         return distanceFromLastNode < index;
 
     return cachedNodeIndex() < index && distanceFromLastNode < index - cachedNodeIndex();
 }
 
-template <typename Collection>
-ALWAYS_INLINE bool CollectionIndexCache<Collection>::isFirstNodeCloserThanCachedNode(unsigned index) const
+template <typename Collection, typename NodeType>
+ALWAYS_INLINE bool CollectionIndexCache<Collection, NodeType>::isFirstNodeCloserThanCachedNode(unsigned index) const
 {
     if (cachedNodeIndex() < index)
         return false;
 
     unsigned distanceFromCachedNode = cachedNodeIndex() - index;
     return index < distanceFromCachedNode;
 }
 
 } // namespace WebCore
 
 #endif // CollectionIndexCache_h