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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 RenderLayerStackingNode;
     46 
     47 // This iterator walks the RenderLayerStackingNode lists in the following order:
     48 // NegativeZOrderChildren -> NormalFlowChildren -> PositiveZOrderChildren.
     49 class RenderLayerStackingNodeIterator {
     50     WTF_MAKE_NONCOPYABLE(RenderLayerStackingNodeIterator);
     51 public:
     52     RenderLayerStackingNodeIterator(const RenderLayerStackingNode& root, unsigned whichChildren)
     53         : m_root(root)
     54         , m_remainingChildren(whichChildren)
     55         , m_index(0)
     56     {
     57     }
     58 
     59     RenderLayerStackingNode* next();
     60 
     61 private:
     62     const RenderLayerStackingNode& m_root;
     63     unsigned m_remainingChildren;
     64     unsigned m_index;
     65 };
     66 
     67 // This iterator is similar to RenderLayerStackingNodeIterator but it walks the lists in reverse order
     68 // (from the last item to the first one).
     69 class RenderLayerStackingNodeReverseIterator {
     70     WTF_MAKE_NONCOPYABLE(RenderLayerStackingNodeReverseIterator);
     71 public:
     72     RenderLayerStackingNodeReverseIterator(const RenderLayerStackingNode& root, unsigned whichChildren)
     73         : m_root(root)
     74         , m_remainingChildren(whichChildren)
     75     {
     76         setIndexToLastItem();
     77     }
     78 
     79     RenderLayerStackingNode* next();
     80 
     81 private:
     82     void setIndexToLastItem();
     83 
     84     const RenderLayerStackingNode& m_root;
     85     unsigned m_remainingChildren;
     86     int m_index;
     87 };
     88 
     89 } // namespace WebCore
     90 
     91 #endif // RenderLayerStackingNodeIterator_h
     92