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1 /* |
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2 * Copyright (c) 2003-2010 Nokia Corporation and/or its subsidiary(-ies). |
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3 * All rights reserved. |
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4 * This component and the accompanying materials are made available |
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5 * under the terms of "Eclipse Public License v1.0" |
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6 * which accompanies this distribution, and is available |
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7 * at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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8 * |
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9 * Initial Contributors: |
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10 * Nokia Corporation - initial contribution. |
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11 * |
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12 * Contributors: |
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13 * |
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14 * Description: |
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15 * Definitions for bidirectional text reordering. |
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16 * |
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17 * |
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18 */ |
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19 |
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20 |
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21 |
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22 #ifndef BIDI_H_ |
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23 #define BIDI_H_ |
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24 |
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25 #include <e32std.h> |
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26 |
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27 class RWriteStream; |
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28 class RReadStream; |
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29 |
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30 |
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31 class TBidirectionalState |
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32 /** |
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33 The bidirectional state class. |
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34 This class contains functions that implement the Unicode Bidirectional Algorithm, |
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35 which changes text from logical order to display order for the correct display |
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36 of right-to-left scripts, like Arabic and Hebrew. A TBidirectionalState object |
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37 carries the embedding level and stack from one line to the next. On construction |
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38 it is in its 'start of paragraph' state. |
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39 @publishedAll |
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40 @released |
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41 */ |
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42 { |
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43 friend class CTBiDi; |
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44 |
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45 public: |
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46 |
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47 class TRunInfo |
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48 /** |
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49 Information about a run of characters with the same bidirectional |
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50 category. |
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51 |
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52 An array of these representing a line is passed into, and reordered by, |
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53 ReorderLine(). |
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54 @publishedAll |
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55 @released |
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56 */ |
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57 { |
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58 public: |
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59 /** Category of a run of text: passed to ReorderLine(); these are |
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60 passed in as TChar::TBdCategory values but are modified for internal |
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61 use. */ |
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62 TUint iCategory; |
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63 /** Embedding level of this run: used internally by ReorderLine(). */ |
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64 TUint8 iEmbeddingLevel; |
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65 /** Resolved direction of this run: 0 for left to right, 1 for right |
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66 to left. */ |
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67 TUint8 iDirection; |
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68 /** Index of this run after reordering. */ |
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69 TInt iIndex; |
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70 /** Start of text; returned by ReorderText(). */ |
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71 TInt iStart; |
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72 /** Length of text; returned by ReorderText(). */ |
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73 TInt iLength; |
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74 }; |
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75 |
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76 IMPORT_C TBidirectionalState(); |
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77 IMPORT_C void ReorderLine(TRunInfo* aRunInfo,TInt aRuns,TBool aParStart,TBool aParEnd,TBool aParRightToLeft, |
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78 TChar::TBdCategory aNextCategory,TChar::TBdCategory aNextStrongCategory, |
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79 TBool& aVisualEndIsAmbiguous); |
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80 IMPORT_C void ReorderLine(TRunInfo* aRunInfo,TInt aRuns,TBool aParStart,TBool aParEnd,TBool aParRightToLeft, |
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81 TChar::TBdCategory aNextCategory,TChar::TBdCategory aNextStrongCategory); |
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82 IMPORT_C static TInt ReorderText(const TText* aText,TInt aLength,TBool aParRightToLeft,TText*& aNewText); |
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83 IMPORT_C static void ReverseGroups(TText* aStart,TInt aLength); |
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84 IMPORT_C void Reset(); |
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85 IMPORT_C TBool IsDefault() const; |
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86 IMPORT_C TBool operator==(const TBidirectionalState& aState) const; |
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87 IMPORT_C void ExternalizeL(RWriteStream& aDest); |
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88 IMPORT_C void InternalizeL(RReadStream& aSource); |
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89 TBool ParRightToLeft() const { return iStack[0].iEmbeddingLevel & 1; } |
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90 |
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91 private: |
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92 // Bidirectional categories coded as bit flags |
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93 enum TCategory |
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94 { |
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95 ELeftToRight = 1 << TChar::ELeftToRight, |
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96 ELeftToRightEmbedding = 1 << TChar::ELeftToRightEmbedding, |
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97 ELeftToRightOverride = 1 << TChar::ELeftToRightOverride, |
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98 ERightToLeft = 1 << TChar::ERightToLeft, |
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99 ERightToLeftArabic = 1 << TChar::ERightToLeftArabic, |
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100 ERightToLeftEmbedding = 1 << TChar::ERightToLeftEmbedding, |
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101 ERightToLeftOverride = 1 << TChar::ERightToLeftOverride, |
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102 EPopDirectionalFormat = 1 << TChar::EPopDirectionalFormat, |
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103 EEuropeanNumber = 1 << TChar::EEuropeanNumber, |
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104 EEuropeanNumberSeparator = 1 << TChar::EEuropeanNumberSeparator, |
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105 EEuropeanNumberTerminator = 1 << TChar::EEuropeanNumberTerminator, |
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106 EArabicNumber = 1 << TChar::EArabicNumber, |
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107 ECommonNumberSeparator = 1 << TChar::ECommonNumberSeparator, |
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108 ENonSpacingMark = 1 << TChar::ENonSpacingMark, |
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109 EBoundaryNeutral = 1 << TChar::EBoundaryNeutral, |
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110 EParagraphSeparator = 1 << TChar::EParagraphSeparator, |
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111 ESegmentSeparator = 1 << TChar::ESegmentSeparator, |
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112 EWhitespace = 1 << TChar::EWhitespace, |
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113 EOtherNeutral = 1 << TChar::EOtherNeutral, |
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114 |
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115 // useful groups |
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116 EBdControlsGroup = ELeftToRightEmbedding | ERightToLeftEmbedding | |
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117 ELeftToRightOverride | ERightToLeftOverride | EPopDirectionalFormat, |
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118 ELeftToRightGroup = ELeftToRight | EEuropeanNumber | ELeftToRightOverride | ELeftToRightEmbedding, |
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119 ERightToLeftGroup = ERightToLeft | EArabicNumber | ERightToLeftArabic | ERightToLeftOverride | |
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120 ERightToLeftEmbedding, |
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121 EStrongGroup = ELeftToRightEmbedding | ERightToLeftEmbedding |
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122 | ELeftToRightOverride | ERightToLeftOverride |
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123 | ELeftToRight | ERightToLeft | ERightToLeftArabic, |
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124 |
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125 ENoCategory = 0 |
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126 }; |
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127 |
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128 enum |
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129 { |
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130 EMaxExplicitLevel = 61, |
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131 EMaxLevel = 63, |
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132 EMaxStackLevels = 62 |
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133 }; |
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134 |
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135 enum TOverrideState |
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136 { |
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137 ENoOverrideState = 0, |
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138 ELeftToRightOverrideState = ELeftToRightOverride, |
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139 ERightToLeftOverrideState = ERightToLeftOverride |
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140 }; |
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141 |
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142 class TStackItem |
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143 { |
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144 public: |
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145 TUint8 iEmbeddingLevel; // embedding level |
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146 TOverrideState iOverrideState; // directional override state |
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147 TCategory iStartCategory; // category that started this level; EOtherNeutral if none |
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148 }; |
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149 |
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150 private: |
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151 /** The information needed during line reordering. |
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152 WARNING: Class for internal use ONLY. Compatibility is not guaranteed in future releases. |
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153 */ |
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154 class TReorderContext |
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155 { |
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156 public: |
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157 void SetNextCategory(TChar::TBdCategory aCat); |
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158 void SetNextStrongCategory(TChar::TBdCategory aCat); |
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159 public: |
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160 /** Category at start of next line, or ON if at the end of the |
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161 paragraph. */ |
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162 TCategory iNextCategory; |
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163 /** Which of L, R or AL appears first in the remainder of the |
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164 paragraph, or ON if none. */ |
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165 TCategory iNextStrongCategory; |
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166 /** The run array for this line. */ |
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167 TRunInfo* iRunInfo; |
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168 /** The length of iRunInfo. */ |
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169 TInt iRuns; |
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170 /** Bitmap of categories currently present in iRunInfo. */ |
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171 TUint32 iCategories; |
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172 /** Found by the algorithm to set iPreviousStrongCategory. */ |
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173 TCategory iLastStrongCategory; |
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174 }; |
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175 |
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176 public: |
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177 static TInt GenerateBdRunArray(const TText* aText, TInt aLength, |
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178 TBidirectionalState::TRunInfo* aRun, TInt aMaxRuns); |
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179 |
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180 private: |
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181 const TStackItem& State() const { return iStack[iStackLevel]; } |
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182 TCategory Push(TCategory aStartCategory); |
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183 TCategory Pop(); |
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184 |
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185 public: |
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186 TBidirectionalState(TChar::TBdCategory aPrevCat, |
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187 TChar::TBdCategory aPrevStrongCat, TBool aParRightToLeft); |
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188 void HandleBdControls(TReorderContext& aContext); |
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189 void ResolveWeakTypesW1W2W3(TReorderContext& aContext); |
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190 void ResolveWeakTypesW4W5W6(TReorderContext& aContext); |
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191 void ResolveWeakTypesW7(TReorderContext& aContext); |
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192 void ResolveNeutralTypes(TReorderContext& aContext); |
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193 void ResolveImplicitLevels(TReorderContext& aContext); |
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194 void PrepareForNextLine(const TReorderContext& aContext); |
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195 void ReorderRuns(TReorderContext& aContext); |
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196 static TInt CatToNumber(TInt aCat); |
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197 static TCategory CharToBdCat(TChar::TBdCategory aCat); |
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198 static TCategory UintToBdCat(TUint aCat); |
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199 static void DeneutralizeRuns(TRunInfo* aStart, TRunInfo* aEnd, |
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200 TCategory aStartCategory, TCategory aEndCategory); |
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201 private: |
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202 TCategory iPreviousCategory; // category at end of last line, or EStartOfParagraph if at start of par |
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203 TCategory iPreviousStrongCategory; // L or R; derived from embedding level if at start of par |
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204 TInt16 iStackLevel; // current stack level |
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205 TInt8 iPushesBeyond60; // number of times Push called with iStackLevel == 60 and Left-To-Right category |
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206 TInt8 iPushesBeyond61; // number of times Push called with iStackLevel == 61 |
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207 TStackItem iStack[EMaxStackLevels]; // the stack of embedding levels |
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208 }; |
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209 |
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210 #endif // BIDI_H_ |