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      1 /*
      2  * Copyright (C) 2013 Google 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 are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef RenderLayerStackingNodeIterator_h
     32 #define RenderLayerStackingNodeIterator_h
     33 
     34 #include "wtf/Noncopyable.h"
     35 
     36 namespace WebCore {
     37 
     38 enum ChildrenIteration {
     39     NegativeZOrderChildren = 1,
     40     NormalFlowChildren = 1 << 1,
     41     PositiveZOrderChildren = 1 << 2,
     42     AllChildren = NegativeZOrderChildren | NormalFlowChildren | PositiveZOrderChildren
     43 };
     44 
     45 class RenderLayer;
     46 class RenderLayerStackingNode;
     47 
     48 // This iterator walks the RenderLayerStackingNode lists in the following order:
     49 // NegativeZOrderChildren -> NormalFlowChildren -> PositiveZOrderChildren.
     50 class RenderLayerStackingNodeIterator {
     51     WTF_MAKE_NONCOPYABLE(RenderLayerStackingNodeIterator);
     52 public:
     53     RenderLayerStackingNodeIterator(const RenderLayerStackingNode& root, unsigned whichChildren)
     54         : m_root(root)
     55         , m_remainingChildren(whichChildren)
     56         , m_index(0)
     57     {
     58     }
     59 
     60     RenderLayerStackingNode* next();
     61 
     62 private:
     63     const RenderLayerStackingNode& m_root;
     64     unsigned m_remainingChildren;
     65     unsigned m_index;
     66 };
     67 
     68 // This iterator is similar to RenderLayerStackingNodeIterator but it walks the lists in reverse order
     69 // (from the last item to the first one).
     70 class RenderLayerStackingNodeReverseIterator {
     71     WTF_MAKE_NONCOPYABLE(RenderLayerStackingNodeReverseIterator);
     72 public:
     73     RenderLayerStackingNodeReverseIterator(const RenderLayerStackingNode& root, unsigned whichChildren)
     74         : m_root(root)
     75         , m_remainingChildren(whichChildren)
     76     {
     77         setIndexToLastItem();
     78     }
     79 
     80     RenderLayerStackingNode* next();
     81 
     82 private:
     83     void setIndexToLastItem();
     84 
     85     const RenderLayerStackingNode& m_root;
     86     unsigned m_remainingChildren;
     87     int m_index;
     88 };
     89 
     90 } // namespace WebCore
     91 
     92 #endif // RenderLayerStackingNodeIterator_h
     93