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      1 /*
      2  * Copyright (C) 2000 Lars Knoll (knoll (at) kde.org)
      3  * Copyright (C) 2003, 2004, 2006, 2007, 2009, 2010 Apple Inc. All right reserved.
      4  *
      5  * This library is free software; you can redistribute it and/or
      6  * modify it under the terms of the GNU Library General Public
      7  * License as published by the Free Software Foundation; either
      8  * version 2 of the License, or (at your option) any later version.
      9  *
     10  * This library is distributed in the hope that it will be useful,
     11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13  * Library General Public License for more details.
     14  *
     15  * You should have received a copy of the GNU Library General Public License
     16  * along with this library; see the file COPYING.LIB.  If not, write to
     17  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     18  * Boston, MA 02110-1301, USA.
     19  *
     20  */
     21 
     22 #ifndef BidiContext_h
     23 #define BidiContext_h
     24 
     25 #include <wtf/Assertions.h>
     26 #include <wtf/PassRefPtr.h>
     27 #include <wtf/RefCounted.h>
     28 #include <wtf/RefPtr.h>
     29 #include <wtf/unicode/Unicode.h>
     30 
     31 namespace WebCore {
     32 
     33 enum BidiEmbeddingSource {
     34     FromStyleOrDOM,
     35     FromUnicode
     36 };
     37 
     38 // Used to keep track of explicit embeddings.
     39 class BidiContext : public RefCounted<BidiContext> {
     40 public:
     41     static PassRefPtr<BidiContext> create(unsigned char level, WTF::Unicode::Direction, bool override = false, BidiEmbeddingSource = FromStyleOrDOM, BidiContext* parent = 0);
     42 
     43     BidiContext* parent() const { return m_parent.get(); }
     44     unsigned char level() const { return m_level; }
     45     WTF::Unicode::Direction dir() const { return static_cast<WTF::Unicode::Direction>(m_direction); }
     46     bool override() const { return m_override; }
     47     BidiEmbeddingSource source() const { return static_cast<BidiEmbeddingSource>(m_source); }
     48 
     49     PassRefPtr<BidiContext> copyStackRemovingUnicodeEmbeddingContexts();
     50 private:
     51     BidiContext(unsigned char level, WTF::Unicode::Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent)
     52         : m_level(level)
     53         , m_direction(direction)
     54         , m_override(override)
     55         , m_source(source)
     56         , m_parent(parent)
     57     {
     58     }
     59 
     60     static PassRefPtr<BidiContext> createUncached(unsigned char level, WTF::Unicode::Direction, bool override, BidiEmbeddingSource, BidiContext* parent);
     61 
     62     unsigned char m_level;
     63     unsigned m_direction : 5; // Direction
     64     bool m_override : 1;
     65     unsigned m_source : 1; // BidiEmbeddingSource
     66     RefPtr<BidiContext> m_parent;
     67 };
     68 
     69 inline unsigned char nextGreaterOddLevel(unsigned char level)
     70 {
     71     return (level + 1) | 1;
     72 }
     73 
     74 inline unsigned char nextGreaterEvenLevel(unsigned char level)
     75 {
     76     return (level + 2) & ~1;
     77 }
     78 
     79 bool operator==(const BidiContext&, const BidiContext&);
     80 
     81 } // namespace WebCore
     82 
     83 #endif // BidiContext_h
     84