Introduce typed Node/Element iterators for range-based for loops of C++11.

Source/core/dom/NodeTraversal.h

 /*
  * 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) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2014 Samsung Electronics. 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 NodeTraversal_h
 #define NodeTraversal_h
 
 #include "core/dom/ContainerNode.h"
 #include "core/dom/Node.h"
 
 namespace blink {
 
+template <class Iterator> class TraversalRange;
+template <class TraversalNext> class TraversalChildrenIterator;
+template <class TraversalNext> class TraversalDescendantIterator;
+template <class TraversalNext> class TraversalInclusiveDescendantIterator;
+template <class TraversalNext> class TraversalNextIterator;
+
 class NodeTraversal {
 public:
+    using TraversalNodeType = Node;
     // Does a pre-order traversal of the tree to find the next node after this one.
     // This uses the same order that tags appear in the source file. If the stayWithin
     // argument is non-null, the traversal will stop once the specified node is reached.
     // This can be used to restrict traversal to a particular sub-tree.
     static Node* next(const Node& current) { return traverseNextTemplate(current); }
     static Node* next(const ContainerNode& current) { return traverseNextTemplate(current); }
     static Node* next(const Node& current, const Node* stayWithin) { return traverseNextTemplate(current, stayWithin); }
     static Node* next(const ContainerNode& current, const Node* stayWithin) { return traverseNextTemplate(current, stayWithin); }
 
     // Like next, but skips children and starts with the next sibling.
     static Node* nextSkippingChildren(const Node&);
     static Node* nextSkippingChildren(const Node&, const Node* stayWithin);
 
+    static Node* firstWithin(const Node& current) { return current.firstChild(); }
+
     static Node* lastWithin(const ContainerNode&);
     static Node& lastWithinOrSelf(Node&);
 
     // Does a reverse pre-order traversal to find the node that comes before the current one in document order
     static Node* previous(const Node&, const Node* stayWithin = 0);
 
     // Like previous, but skips children and starts with the next sibling.
     static Node* previousSkippingChildren(const Node&, const Node* stayWithin = 0);
 
     // Like next, but visits parents after their children.
     static Node* nextPostOrder(const Node&, const Node* stayWithin = 0);
 
     // Like previous, but visits parents before their children.
     static Node* previousPostOrder(const Node&, const Node* stayWithin = 0);
 
     // Pre-order traversal including the pseudo-elements.
     static Node* previousIncludingPseudo(const Node&, const Node* stayWithin = 0);
     static Node* nextIncludingPseudo(const Node&, const Node* stayWithin = 0);
     static Node* nextIncludingPseudoSkippingChildren(const Node&, const Node* stayWithin = 0);
 
     static Node* nextAncestorSibling(const Node&);
     static Node* nextAncestorSibling(const Node&, const Node* stayWithin);
     static Node& highestAncestorOrSelf(Node&);
 
     // Children traversal.
     static Node* childAt(const Node& parent, unsigned index) { return childAtTemplate(parent, index); }
     static Node* childAt(const ContainerNode& parent, unsigned index) { return childAtTemplate(parent, index); }
 
+    static Node* nextSibling(const Node& node) { return node.nextSibling(); }
+
+    static TraversalRange<TraversalChildrenIterator<NodeTraversal>> childrenOf(const Node&);
+    static TraversalRange<TraversalDescendantIterator<NodeTraversal>> descendantsOf(const Node&);
+    static TraversalRange<TraversalInclusiveDescendantIterator<NodeTraversal>> inclusiveDescendantsOf(const Node&);
+    static TraversalRange<TraversalNextIterator<NodeTraversal>> fromNext(const Node&);
+
 private:
     template <class NodeType>
     static Node* traverseNextTemplate(NodeType&);
     template <class NodeType>
     static Node* traverseNextTemplate(NodeType&, const Node* stayWithin);
     template <class NodeType>
     static Node* childAtTemplate(NodeType&, unsigned);
 };
 
+template <class Iterator>
+class TraversalRange {
+public:
+    using StartNodeType = typename Iterator::StartNodeType;
+    explicit TraversalRange(const StartNodeType& start) : m_start(start) { }
+    Iterator begin() { return Iterator(m_start); }
+    Iterator end() { return Iterator::end(); }
+private:
+    const StartNodeType& m_start;
+};
+
+template <class TraversalNext>
+class TraversalIteratorBase {
+public:
+    using NodeType = typename TraversalNext::TraversalNodeType;
+    NodeType& operator*() { return *m_current; }
+    bool operator!=(const TraversalIteratorBase& rval) const { return m_current != rval.m_current ; }
+protected:
+    explicit TraversalIteratorBase(NodeType* current) : m_current(current) { };
+    NodeType* m_current;
+};
+
+template <class TraversalNext>
+class TraversalChildrenIterator : public TraversalIteratorBase<TraversalNext> {
+public:
+    using StartNodeType = Node;
+    using TraversalIteratorBase<TraversalNext>::m_current;
+    explicit TraversalChildrenIterator(const StartNodeType& start) : TraversalIteratorBase<TraversalNext>(TraversalNext::firstWithin(start)) { };
+    void operator++() { m_current = TraversalNext::nextSibling(*m_current); };
+    static TraversalChildrenIterator end() { return TraversalChildrenIterator(); };
+private:
+    TraversalChildrenIterator() : TraversalIteratorBase<TraversalNext>(nullptr) { };
+};
+
+template <class TraversalNext>
+class TraversalNextIterator : public TraversalIteratorBase<TraversalNext> {
+public:
+    using StartNodeType = Node;
+    using TraversalIteratorBase<TraversalNext>::m_current;
+    explicit TraversalNextIterator(const StartNodeType& start) : TraversalIteratorBase<TraversalNext>(TraversalNext::next(start)) { };
+    void operator++() { m_current = TraversalNext::next(*m_current); }
+    static TraversalNextIterator end() { return TraversalNextIterator(); };
+private:
+    TraversalNextIterator() : TraversalIteratorBase<TraversalNext>(nullptr) { };
+};
+
+template <class TraversalNext>
+class TraversalDescendantIterator : public TraversalIteratorBase<TraversalNext> {
+public:
+    using StartNodeType = Node;
+    using TraversalIteratorBase<TraversalNext>::m_current;
+    explicit TraversalDescendantIterator(const StartNodeType& start) : TraversalIteratorBase<TraversalNext>(TraversalNext::firstWithin(start)), m_root(&start) { };
+    void operator++() { m_current = TraversalNext::next(*m_current, m_root); }
+    static TraversalDescendantIterator end() { return TraversalDescendantIterator(); };
+private:
+    TraversalDescendantIterator() : TraversalIteratorBase<TraversalNext>(nullptr), m_root(nullptr) { };
+    const Node* m_root;
+};
+
+template <class TraversalNext>
+class TraversalInclusiveDescendantIterator : public TraversalIteratorBase<TraversalNext> {
+public:
+    using StartNodeType = typename TraversalNext::TraversalNodeType;
+    using NodeType = typename TraversalNext::TraversalNodeType;
+    using TraversalIteratorBase<TraversalNext>::m_current;
+    explicit TraversalInclusiveDescendantIterator(const StartNodeType& start) : TraversalIteratorBase<TraversalNext>(const_cast<NodeType*>(&start)), m_root(&start) { };
+    void operator++() { m_current = TraversalNext::next(*m_current, m_root); }
+    static TraversalInclusiveDescendantIterator end() { return TraversalInclusiveDescendantIterator(); };
+private:
+    TraversalInclusiveDescendantIterator() : TraversalIteratorBase<TraversalNext>(nullptr), m_root(nullptr) { };
+    const StartNodeType* m_root;
+};
+
+inline TraversalRange<TraversalChildrenIterator<NodeTraversal>> NodeTraversal::childrenOf(const Node& parent)
+{
+    return TraversalRange<TraversalChildrenIterator<NodeTraversal>>(parent);
+}
+
+inline TraversalRange<TraversalDescendantIterator<NodeTraversal>> NodeTraversal::descendantsOf(const Node& root)
+{
+    return TraversalRange<TraversalDescendantIterator<NodeTraversal>>(root);
+}
+
+inline TraversalRange<TraversalInclusiveDescendantIterator<NodeTraversal>> NodeTraversal::inclusiveDescendantsOf(const Node& root)
+{
+    return TraversalRange<TraversalInclusiveDescendantIterator<NodeTraversal>>(root);
+}
+
+inline TraversalRange<TraversalNextIterator<NodeTraversal>> NodeTraversal::fromNext(const Node& start)
+{
+    return TraversalRange<TraversalNextIterator<NodeTraversal>>(start);
+};
+
 template <class NodeType>
 inline Node* NodeTraversal::traverseNextTemplate(NodeType& current)
 {
     if (current.hasChildren())
         return current.firstChild();
     if (current.nextSibling())
         return current.nextSibling();
     return nextAncestorSibling(current);
 }
 
@@ skipping 38 matching lines @@
 {
     Node* child = parent.firstChild();
     while (child && index--)
         child = child->nextSibling();
     return child;
 }
 
 } // namespace blink
 
 #endif