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 "platform/PlatformExport.h" 26 #include "wtf/Assertions.h" 27 #include "wtf/PassRefPtr.h" 28 #include "wtf/RefCounted.h" 29 #include "wtf/RefPtr.h" 30 #include "wtf/unicode/Unicode.h" 31 32 namespace blink { 33 34 enum BidiEmbeddingSource { 35 FromStyleOrDOM, 36 FromUnicode 37 }; 38 39 // Used to keep track of explicit embeddings. 40 class PLATFORM_EXPORT BidiContext : public RefCounted<BidiContext> { 41 public: 42 static PassRefPtr<BidiContext> create(unsigned char level, WTF::Unicode::Direction, bool override = false, BidiEmbeddingSource = FromStyleOrDOM, BidiContext* parent = 0); 43 44 BidiContext* parent() const { return m_parent.get(); } 45 unsigned char level() const { return m_level; } 46 WTF::Unicode::Direction dir() const { return static_cast<WTF::Unicode::Direction>(m_direction); } 47 bool override() const { return m_override; } 48 BidiEmbeddingSource source() const { return static_cast<BidiEmbeddingSource>(m_source); } 49 50 PassRefPtr<BidiContext> copyStackRemovingUnicodeEmbeddingContexts(); 51 52 // http://www.unicode.org/reports/tr9/#Modifications 53 // 6.3 raised the limit from 61 to 125. 54 // http://unicode.org/reports/tr9/#BD2 55 static const unsigned char kMaxLevel = 125; 56 57 private: 58 BidiContext(unsigned char level, WTF::Unicode::Direction direction, bool override, BidiEmbeddingSource source, BidiContext* parent) 59 : m_level(level) 60 , m_direction(direction) 61 , m_override(override) 62 , m_source(source) 63 , m_parent(parent) 64 { 65 ASSERT(level <= kMaxLevel); 66 } 67 68 static PassRefPtr<BidiContext> createUncached(unsigned char level, WTF::Unicode::Direction, bool override, BidiEmbeddingSource, BidiContext* parent); 69 70 unsigned m_level : 7; // The maximium bidi level is 125: http://unicode.org/reports/tr9/#Explicit_Levels_and_Directions 71 unsigned m_direction : 5; // Direction 72 unsigned m_override : 1; 73 unsigned m_source : 1; // BidiEmbeddingSource 74 RefPtr<BidiContext> m_parent; 75 }; 76 77 inline unsigned char nextGreaterOddLevel(unsigned char level) 78 { 79 return (level + 1) | 1; 80 } 81 82 inline unsigned char nextGreaterEvenLevel(unsigned char level) 83 { 84 return (level + 2) & ~1; 85 } 86 87 PLATFORM_EXPORT bool operator==(const BidiContext&, const BidiContext&); 88 89 } // namespace blink 90 91 #endif // BidiContext_h 92
