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      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
     65