WebCore/NodeWithIndex.h

   1 /*
   2  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef NodeWithIndex_h
  27 #define NodeWithIndex_h
  28
  29 #include "Node.h"
  30
  31 namespace WebCore {
  32
  33 // For use when you want to get the index for a node repeatedly and
  34 // only want to walk the child list to figure out the index once.
  35 class NodeWithIndex {
  36 public:
  37     NodeWithIndex(Node* node)
  38         : m_node(node)
  39         , m_haveIndex(false)
  40     {
  41         ASSERT(node);
  42     }
  43
  44     Node* node() const { return m_node; }
  45
  46     int index() const
  47     {
  48         if (!m_haveIndex) {
  49             m_index = m_node->nodeIndex();
  50             m_haveIndex = true;
  51         }
  52         ASSERT(m_index == static_cast<int>(m_node->nodeIndex()));
  53         return m_index;
  54     }
  55
  56 private:
  57     Node* m_node;
  58     mutable bool m_haveIndex;
  59     mutable int m_index;
  60 };
  61
  62 }
  63
  64 #endif