Add template parameter to ElementTraversal to iterate over Elements of a specific type

Source/core/dom/ElementTraversal.h

Index: Source/core/dom/ElementTraversal.h
diff --git a/Source/core/dom/ElementTraversal.h b/Source/core/dom/ElementTraversal.h
index 2f8ede5aaf8257376e092345d5ad6e83423c571a..6705f04efcd20b8bf281258b366a92797c59998a 100644
--- a/Source/core/dom/ElementTraversal.h
+++ b/Source/core/dom/ElementTraversal.h
@@ -2,7 +2,7 @@
  * 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, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
+ * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2014 Samsung Electronics. All rights reserved.
  *
@@ -31,74 +31,93 @@
 
 namespace WebCore {
 
-class ElementTraversal {
+template <class ElementType>
+class Traversal {
 public:
-    // First / Last element child of the node.
-    static Element* firstWithin(const ContainerNode& current) { return firstElementWithinTemplate(current); }
-    static Element* firstWithin(const Node& current) { return firstElementWithinTemplate(current); }
-    static Element* lastWithin(const ContainerNode& current) { return lastWithinTemplate(current); }
-    static Element* lastWithin(const Node& current) { return lastWithinTemplate(current); }
+    // First or last ElementType child of the node.
+    static ElementType* firstChild(const ContainerNode& current) { return firstChildTemplate(current); }
+    static ElementType* firstChild(const Node& current) { return firstChildTemplate(current); }
+    static ElementType* lastChild(const ContainerNode& current) { return lastChildTemplate(current); }
+    static ElementType* lastChild(const Node& current) { return lastChildTemplate(current); }
+
+    // First or last ElementType descendant of the node.
+    // For Elements firstWithin() is always the same as firstChild().
+    static ElementType* firstWithin(const ContainerNode& current) { return firstWithinTemplate(current); }
+    static ElementType* firstWithin(const Node& current) { return firstWithinTemplate(current); }
+    static ElementType* lastWithin(const ContainerNode& current) { return lastWithinTemplate(current); }
+    static ElementType* lastWithin(const Node& current) { return lastWithinTemplate(current); }
 
     // Pre-order traversal skipping non-element nodes.
-    static Element* next(const ContainerNode& current) { return traverseNextElementTemplate(current); }
-    static Element* next(const Node& current) { return traverseNextElementTemplate(current); }
-    static Element* next(const ContainerNode& current, const Node* stayWithin) { return traverseNextElementTemplate(current, stayWithin); }
-    static Element* next(const Node& current, const Node* stayWithin) { return traverseNextElementTemplate(current, stayWithin); }
+    static ElementType* next(const ContainerNode& current) { return nextTemplate(current); }
+    static ElementType* next(const Node& current) { return nextTemplate(current); }
+    static ElementType* next(const ContainerNode& current, const Node* stayWithin) { return nextTemplate(current, stayWithin); }
+    static ElementType* next(const Node& current, const Node* stayWithin) { return nextTemplate(current, stayWithin); }
+    static ElementType* previous(const ContainerNode& current) { return previousTemplate(current); }
+    static ElementType* previous(const Node& current) { return previousTemplate(current); }
+    static ElementType* previous(const ContainerNode& current, const Node* stayWithin) { return previousTemplate(current, stayWithin); }
+    static ElementType* previous(const Node& current, const Node* stayWithin) { return previousTemplate(current, stayWithin); }
 
     // Like next, but skips children.
-    static Element* nextSkippingChildren(const ContainerNode& current) { return traverseNextElementSkippingChildrenTemplate(current); }
-    static Element* nextSkippingChildren(const Node& current) { return traverseNextElementSkippingChildrenTemplate(current); }
-    static Element* nextSkippingChildren(const ContainerNode& current, const Node* stayWithin) { return traverseNextElementSkippingChildrenTemplate(current, stayWithin); }
-    static Element* nextSkippingChildren(const Node& current, const Node* stayWithin) { return traverseNextElementSkippingChildrenTemplate(current, stayWithin); }
+    static ElementType* nextSkippingChildren(const ContainerNode& current) { return nextSkippingChildrenTemplate(current); }
+    static ElementType* nextSkippingChildren(const Node& current) { return nextSkippingChildrenTemplate(current); }
+    static ElementType* nextSkippingChildren(const ContainerNode& current, const Node* stayWithin) { return nextSkippingChildrenTemplate(current, stayWithin); }
+    static ElementType* nextSkippingChildren(const Node& current, const Node* stayWithin) { return nextSkippingChildrenTemplate(current, stayWithin); }
 
     // Pre-order traversal including the pseudo-elements.
-    static Element* previousIncludingPseudo(const Node&, const Node* stayWithin = 0);
-    static Element* nextIncludingPseudo(const Node&, const Node* stayWithin = 0);
-    static Element* nextIncludingPseudoSkippingChildren(const Node&, const Node* stayWithin = 0);
+    static ElementType* previousIncludingPseudo(const Node&, const Node* stayWithin = 0);
+    static ElementType* nextIncludingPseudo(const Node&, const Node* stayWithin = 0);
+    static ElementType* nextIncludingPseudoSkippingChildren(const Node&, const Node* stayWithin = 0);
 
     // Utility function to traverse only the element and pseudo-element siblings of a node.
-    static Element* pseudoAwarePreviousSibling(const Node&);
+    static ElementType* pseudoAwarePreviousSibling(const Node&);
 
     // Previous / Next sibling.
-    static Element* previousSibling(const Node&);
-    static Element* nextSibling(const Node&);
+    static ElementType* previousSibling(const Node&);
+    static ElementType* nextSibling(const Node&);
 
 private:
     template <class NodeType>
-    static Element* firstElementWithinTemplate(NodeType&);
+    static ElementType* firstChildTemplate(NodeType&);
+    template <class NodeType>
+    static ElementType* lastChildTemplate(NodeType&);
+    template <class NodeType>
+    static ElementType* firstWithinTemplate(NodeType&);
+    template <class NodeType>
+    static ElementType* lastWithinTemplate(NodeType&);
+    template <class NodeType>
+    static ElementType* nextTemplate(NodeType&);
     template <class NodeType>
-    static Element* lastWithinTemplate(NodeType&);
+    static ElementType* nextTemplate(NodeType&, const Node* stayWithin);
     template <class NodeType>
-    static Element* traverseNextElementTemplate(NodeType&);
+    static ElementType* previousTemplate(NodeType&);
     template <class NodeType>
-    static Element* traverseNextElementTemplate(NodeType&, const Node* stayWithin);
+    static ElementType* previousTemplate(NodeType&, const Node* stayWithin);
     template <class NodeType>
-    static Element* traverseNextElementSkippingChildrenTemplate(NodeType&);
+    static ElementType* nextSkippingChildrenTemplate(NodeType&);
     template <class NodeType>
-    static Element* traverseNextElementSkippingChildrenTemplate(NodeType&, const Node* stayWithin);
+    static ElementType* nextSkippingChildrenTemplate(NodeType&, const Node* stayWithin);
 };
 
+typedef Traversal<Element> ElementTraversal;
+
+// Specialized for pure Element to exploit the fact that Elements parent is always either another Element or the root.
+template <>
 template <class NodeType>
-inline Element* ElementTraversal::firstElementWithinTemplate(NodeType& current)
+inline Element* Traversal<Element>::firstWithinTemplate(NodeType& current)
 {
-    // Except for the root containers, only elements can have element children.
-    Node* node = current.firstChild();
-    while (node && !node->isElementNode())
-        node = node->nextSibling();
-    return toElement(node);
+    return firstChildTemplate(current);
 }
 
+template <>
 template <class NodeType>
-inline Element* ElementTraversal::lastWithinTemplate(NodeType& current)
+inline Element* Traversal<Element>::lastWithinTemplate(NodeType& current)
 {
-    Node* node = current.lastChild();
-    while (node && !node->isElementNode())
-        node = node->previousSibling();
-    return toElement(node);
+    return lastChildTemplate(current);
 }
 
+template <>
 template <class NodeType>
-inline Element* ElementTraversal::traverseNextElementTemplate(NodeType& current)
+inline Element* Traversal<Element>::nextTemplate(NodeType& current)
 {
     Node* node = NodeTraversal::next(current);
     while (node && !node->isElementNode())
@@ -106,8 +125,9 @@ inline Element* ElementTraversal::traverseNextElementTemplate(NodeType& current)
     return toElement(node);
 }
 
+template <>
 template <class NodeType>
-inline Element* ElementTraversal::traverseNextElementTemplate(NodeType& current, const Node* stayWithin)
+inline Element* Traversal<Element>::nextTemplate(NodeType& current, const Node* stayWithin)
 {
     Node* node = NodeTraversal::next(current, stayWithin);
     while (node && !node->isElementNode())
@@ -115,70 +135,179 @@ inline Element* ElementTraversal::traverseNextElementTemplate(NodeType& current,
     return toElement(node);
 }
 
+template <>
 template <class NodeType>
-inline Element* ElementTraversal::traverseNextElementSkippingChildrenTemplate(NodeType& current)
+inline Element* Traversal<Element>::previousTemplate(NodeType& current)
 {
-    Node* node = NodeTraversal::nextSkippingChildren(current);
+    Node* node = NodeTraversal::previous(current);
     while (node && !node->isElementNode())
-        node = NodeTraversal::nextSkippingChildren(*node);
+        node = NodeTraversal::previous(*node);
     return toElement(node);
 }
 
+template <>
 template <class NodeType>
-inline Element* ElementTraversal::traverseNextElementSkippingChildrenTemplate(NodeType& current, const Node* stayWithin)
+inline Element* Traversal<Element>::previousTemplate(NodeType& current, const Node* stayWithin)
 {
-    Node* node = NodeTraversal::nextSkippingChildren(current, stayWithin);
+    Node* node = NodeTraversal::previous(current, stayWithin);
     while (node && !node->isElementNode())
-        node = NodeTraversal::nextSkippingChildren(*node, stayWithin);
+        node = NodeTraversal::previous(*node, stayWithin);
     return toElement(node);
 }
 
-inline Element* ElementTraversal::previousIncludingPseudo(const Node& current, const Node* stayWithin)
+// Generic versions.
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::firstChildTemplate(NodeType& current)
+{
+    Node* node = current.firstChild();
+    while (node && !isElementOfType<const ElementType>(*node))
+        node = node->nextSibling();
+    return toElement<ElementType>(node);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::lastChildTemplate(NodeType& current)
+{
+    Node* node = current.lastChild();
+    while (node && !isElementOfType<const ElementType>(*node))
+        node = node->previousSibling();
+    return toElement<ElementType>(node);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::firstWithinTemplate(NodeType& current)
+{
+    Element* element = Traversal<Element>::firstWithin(current);
+    while (element && !isElementOfType<const ElementType>(*element))
+        element = Traversal<Element>::next(*element, &current);
+    return toElement<ElementType>(element);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::lastWithinTemplate(NodeType& current)
+{
+    Element* element = Traversal<Element>::lastWithin(current);
+    while (element && !isElementOfType<const ElementType>(*element))
+        element = Traversal<Element>::previous(element, &current);
+    return toElement<ElementType>(element);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::nextTemplate(NodeType& current)
+{
+    Element* element = Traversal<Element>::next(current);
+    while (element && !isElementOfType<const ElementType>(*element))
+        element = Traversal<Element>::next(*element);
+    return toElement<ElementType>(element);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::nextTemplate(NodeType& current, const Node* stayWithin)
+{
+    Element* element = Traversal<Element>::next(current, stayWithin);
+    while (element && !isElementOfType<const ElementType>(*element))
+        element = Traversal<Element>::next(*element, stayWithin);
+    return toElement<ElementType>(element);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::previousTemplate(NodeType& current)
+{
+    Element* element = Traversal<Element>::previous(current);
+    while (element && !isElementOfType<const ElementType>(*element))
+        element = Traversal<Element>::previous(*element);
+    return toElement<ElementType>(element);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::previousTemplate(NodeType& current, const Node* stayWithin)
+{
+    Element* element = Traversal<Element>::previous(current, stayWithin);
+    while (element && !isElementOfType<const ElementType>(*element))
+        element = Traversal<Element>::previous(*element, stayWithin);
+    return toElement<ElementType>(element);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::nextSkippingChildrenTemplate(NodeType& current)
+{
+    Node* node = NodeTraversal::nextSkippingChildren(current);
+    while (node && !isElementOfType<const ElementType>(*node))
+        node = NodeTraversal::nextSkippingChildren(*node);
+    return toElement<ElementType>(node);
+}
+
+template <class ElementType>
+template <class NodeType>
+inline ElementType* Traversal<ElementType>::nextSkippingChildrenTemplate(NodeType& current, const Node* stayWithin)
+{
+    Node* node = NodeTraversal::nextSkippingChildren(current, stayWithin);
+    while (node && !isElementOfType<const ElementType>(*node))
+        node = NodeTraversal::nextSkippingChildren(*node, stayWithin);
+    return toElement<ElementType>(node);
+}
+
+template <class ElementType>
+inline ElementType* Traversal<ElementType>::previousIncludingPseudo(const Node& current, const Node* stayWithin)
 {
     Node* node = NodeTraversal::previousIncludingPseudo(current, stayWithin);
-    while (node && !node->isElementNode())
+    while (node && !isElementOfType<const ElementType>(*node))
         node = NodeTraversal::previousIncludingPseudo(*node, stayWithin);
-    return toElement(node);
+    return toElement<ElementType>(node);
 }
 
-inline Element* ElementTraversal::nextIncludingPseudo(const Node& current, const Node* stayWithin)
+template <class ElementType>
+inline ElementType* Traversal<ElementType>::nextIncludingPseudo(const Node& current, const Node* stayWithin)
 {
     Node* node = NodeTraversal::nextIncludingPseudo(current, stayWithin);
-    while (node && !node->isElementNode())
+    while (node && !isElementOfType<const ElementType>(*node))
         node = NodeTraversal::nextIncludingPseudo(*node, stayWithin);
-    return toElement(node);
+    return toElement<ElementType>(node);
 }
 
-inline Element* ElementTraversal::nextIncludingPseudoSkippingChildren(const Node& current, const Node* stayWithin)
+template <class ElementType>
+inline ElementType* Traversal<ElementType>::nextIncludingPseudoSkippingChildren(const Node& current, const Node* stayWithin)
 {
     Node* node = NodeTraversal::nextIncludingPseudoSkippingChildren(current, stayWithin);
-    while (node && !node->isElementNode())
+    while (node && !isElementOfType<const ElementType>(*node))
         node = NodeTraversal::nextIncludingPseudoSkippingChildren(*node, stayWithin);
-    return toElement(node);
+    return toElement<ElementType>(node);
 }
 
-inline Element* ElementTraversal::pseudoAwarePreviousSibling(const Node& current)
+template <class ElementType>
+inline ElementType* Traversal<ElementType>::pseudoAwarePreviousSibling(const Node& current)
 {
     Node* node = current.pseudoAwarePreviousSibling();
-    while (node && !node->isElementNode())
+    while (node && !isElementOfType<const ElementType>(*node))
         node = node->pseudoAwarePreviousSibling();
-    return toElement(node);
+    return toElement<ElementType>(node);
 }
 
-inline Element* ElementTraversal::previousSibling(const Node& current)
+template <class ElementType>
+inline ElementType* Traversal<ElementType>::previousSibling(const Node& current)
 {
     Node* node = current.previousSibling();
-    while (node && !node->isElementNode())
+    while (node && !isElementOfType<const ElementType>(*node))
         node = node->previousSibling();
-    return toElement(node);
+    return toElement<ElementType>(node);
 }
 
-inline Element* ElementTraversal::nextSibling(const Node& current)
+template <class ElementType>
+inline ElementType* Traversal<ElementType>::nextSibling(const Node& current)
 {
     Node* node = current.nextSibling();
-    while (node && !node->isElementNode())
+    while (node && !isElementOfType<const ElementType>(*node))
         node = node->nextSibling();
-    return toElement(node);
+    return toElement<ElementType>(node);
 }
 
 } // namespace WebCore