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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). |
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4 ** All rights reserved. |
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5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
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6 ** |
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7 ** This file is part of the QtXmlPatterns module of the Qt Toolkit. |
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8 ** |
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9 ** $QT_BEGIN_LICENSE:LGPL$ |
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10 ** No Commercial Usage |
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11 ** This file contains pre-release code and may not be distributed. |
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12 ** You may use this file in accordance with the terms and conditions |
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13 ** contained in the Technology Preview License Agreement accompanying |
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14 ** this package. |
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15 ** |
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16 ** GNU Lesser General Public License Usage |
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17 ** Alternatively, this file may be used under the terms of the GNU Lesser |
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18 ** General Public License version 2.1 as published by the Free Software |
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19 ** Foundation and appearing in the file LICENSE.LGPL included in the |
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20 ** packaging of this file. Please review the following information to |
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21 ** ensure the GNU Lesser General Public License version 2.1 requirements |
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22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. |
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23 ** |
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24 ** In addition, as a special exception, Nokia gives you certain additional |
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25 ** rights. These rights are described in the Nokia Qt LGPL Exception |
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26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. |
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27 ** |
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28 ** If you have questions regarding the use of this file, please contact |
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29 ** Nokia at qt-info@nokia.com. |
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30 ** |
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31 ** |
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32 ** |
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33 ** |
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34 ** |
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35 ** |
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36 ** |
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37 ** |
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38 ** $QT_END_LICENSE$ |
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39 ** |
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40 ****************************************************************************/ |
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41 |
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42 // |
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43 // W A R N I N G |
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44 // ------------- |
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45 // |
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46 // This file is not part of the Qt API. It exists purely as an |
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47 // implementation detail. This header file may change from version to |
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48 // version without notice, or even be removed. |
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49 // |
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50 // We mean it. |
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51 |
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52 #ifndef Patternist_OperandsIterator_H |
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53 #define Patternist_OperandsIterator_H |
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54 |
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55 #include <QPair> |
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56 #include <QStack> |
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57 |
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58 #include "qexpression_p.h" |
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59 |
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60 QT_BEGIN_HEADER |
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61 |
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62 QT_BEGIN_NAMESPACE |
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63 |
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64 namespace QPatternist |
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65 { |
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66 /** |
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67 * @short A helper class that iterates a tree of Expression instances. It |
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68 * is not a sub-class of QAbstractXmlForwardIterator. |
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69 * |
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70 * The OperandsIterator delivers all Expression instances that are children at any |
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71 * depth of the Expression passed in the constructor. |
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72 * The order is delivered in a defined way, from left to right and depth |
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73 * first. |
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74 * |
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75 * @author Frans Englich <frans.englich@nokia.com> |
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76 */ |
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77 class OperandsIterator |
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78 { |
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79 /** |
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80 * The second value, the int, is the current position in the first. |
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81 */ |
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82 typedef QPair<Expression::List, int> Level; |
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83 |
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84 public: |
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85 enum TreatParent |
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86 { |
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87 ExcludeParent, |
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88 IncludeParent |
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89 }; |
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90 |
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91 /** |
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92 * if @p treatParent is @c IncludeParent, @p start is excluded. |
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93 * |
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94 * @p start must be a valid Expression. |
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95 */ |
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96 inline OperandsIterator(const Expression::Ptr &start, |
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97 const TreatParent treatParent) |
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98 { |
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99 Q_ASSERT(start); |
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100 if(treatParent == IncludeParent) |
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101 { |
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102 Expression::List l; |
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103 l.append(start); |
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104 m_exprs.push(qMakePair(l, -1)); |
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105 } |
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106 |
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107 m_exprs.push(qMakePair(start->operands(), -1)); |
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108 } |
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109 |
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110 /** |
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111 * @short Returns the current Expression and advances the iterator. |
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112 * |
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113 * If the end has been reached, a default constructed pointer is |
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114 * returned. |
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115 * |
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116 * We intentionally return by reference. |
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117 */ |
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118 inline Expression::Ptr next() |
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119 { |
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120 if(m_exprs.isEmpty()) |
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121 return Expression::Ptr(); |
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122 |
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123 Level &lvl = m_exprs.top(); |
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124 ++lvl.second; |
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125 |
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126 if(lvl.second == lvl.first.size()) |
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127 { |
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128 /* Resume iteration above us. */ |
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129 m_exprs.pop(); |
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130 |
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131 if(m_exprs.isEmpty()) |
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132 return Expression::Ptr(); |
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133 |
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134 while(true) |
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135 { |
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136 Level &previous = m_exprs.top(); |
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137 ++previous.second; |
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138 |
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139 if(previous.second < previous.first.count()) |
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140 { |
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141 const Expression::Ptr &op = previous.first.at(previous.second); |
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142 m_exprs.push(qMakePair(op->operands(), -1)); |
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143 return op; |
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144 } |
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145 else |
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146 { |
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147 // We have already reached the end of this level. |
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148 m_exprs.pop(); |
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149 if(m_exprs.isEmpty()) |
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150 return Expression::Ptr(); |
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151 } |
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152 } |
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153 } |
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154 else |
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155 { |
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156 const Expression::Ptr &op = lvl.first.at(lvl.second); |
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157 m_exprs.push(qMakePair(op->operands(), -1)); |
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158 return op; |
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159 } |
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160 } |
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161 |
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162 /** |
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163 * Advances this iterator by the current expression and its operands. |
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164 */ |
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165 Expression::Ptr skipOperands() |
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166 { |
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167 if(m_exprs.isEmpty()) |
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168 return Expression::Ptr(); |
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169 |
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170 Level &lvl = m_exprs.top(); |
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171 ++lvl.second; |
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172 |
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173 if(lvl.second == lvl.first.size()) |
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174 { |
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175 /* We've reached the end of this level, at least. */ |
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176 m_exprs.pop(); |
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177 } |
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178 |
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179 return next(); |
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180 } |
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181 |
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182 private: |
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183 Q_DISABLE_COPY(OperandsIterator) |
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184 |
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185 QStack<Level> m_exprs; |
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186 }; |
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187 } |
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188 |
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189 |
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190 QT_END_NAMESPACE |
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191 QT_END_HEADER |
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192 |
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193 #endif |