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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_SequenceMappingIterator_H |
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53 #define Patternist_SequenceMappingIterator_H |
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54 |
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55 #include "qabstractxmlforwarditerator_p.h" |
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56 #include "qdynamiccontext_p.h" |
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57 |
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58 QT_BEGIN_HEADER |
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59 |
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60 QT_BEGIN_NAMESPACE |
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61 |
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62 namespace QPatternist |
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63 { |
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64 /** |
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65 * @short Proxies another QAbstractXmlForwardIterator, and for each item, returns the |
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66 * Sequence returned from a mapping function. |
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67 * |
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68 * ItemMappingIterator is practical when the items in an QAbstractXmlForwardIterator needs to |
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69 * be translated to another sequence, while still doing it in a pipe-lined |
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70 * fashion. In contrast to ItemMappingIterator, SequenceMappingIterator maps |
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71 * each item into another QAbstractXmlForwardIterator, and where the SequenceMappingIterator's own |
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72 * result is the concatenation of all those Iterators. Hence, while ItemMappingIterator |
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73 * is better tailored for one-to-one or one-to-zero conversion, SequenceMappingIterator |
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74 * is more suitable for one-to-many conversion. |
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75 * |
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76 * This is achieved by that SequenceMappingIterator's constructor takes |
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77 * an instance of a class, that must have the following member: |
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78 * |
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79 * @code |
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80 * QAbstractXmlForwardIterator<TResult>::Ptr mapToSequence(const TSource::Ptr &item, |
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81 * const DynamicContext::Ptr &context) const; |
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82 * @endcode |
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83 * |
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84 * @author Frans Englich <frans.englich@nokia.com> |
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85 * @see ItemMappingIterator |
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86 * @ingroup Patternist_iterators |
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87 */ |
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88 template<typename TResult, typename TSource, typename TMapper> |
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89 class SequenceMappingIterator : public QAbstractXmlForwardIterator<TResult> |
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90 { |
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91 public: |
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92 /** |
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93 * Constructs a SequenceMappingIterator. |
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94 * |
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95 * @param mapper the object that has the mapToItem() sequence. |
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96 * @param sourceIterator the QAbstractXmlForwardIterator whose items should be mapped. |
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97 * @param context the DynamicContext that will be passed to the map function. |
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98 * May be null. |
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99 */ |
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100 SequenceMappingIterator(const TMapper &mapper, |
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101 const typename QAbstractXmlForwardIterator<TSource>::Ptr &sourceIterator, |
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102 const DynamicContext::Ptr &context); |
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103 |
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104 virtual TResult next(); |
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105 virtual xsInteger count(); |
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106 virtual TResult current() const; |
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107 virtual xsInteger position() const; |
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108 |
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109 /** |
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110 * The reason the implementation is placed in line here, is due to a bug |
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111 * in MSVC-2005 version 14.00.50727.762. Note that it works with version 14.00.50727.42. |
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112 */ |
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113 virtual typename QAbstractXmlForwardIterator<TResult>::Ptr copy() const |
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114 { |
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115 return typename QAbstractXmlForwardIterator<TResult>::Ptr |
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116 (new SequenceMappingIterator<TResult, TSource, TMapper>(m_mapper, |
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117 m_mainIterator->copy(), |
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118 m_context)); |
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119 } |
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120 |
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121 private: |
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122 xsInteger m_position; |
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123 TResult m_current; |
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124 typename QAbstractXmlForwardIterator<TSource>::Ptr m_mainIterator; |
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125 typename QAbstractXmlForwardIterator<TResult>::Ptr m_currentIterator; |
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126 const typename DynamicContext::Ptr m_context; |
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127 const TMapper m_mapper; |
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128 }; |
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129 |
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130 template<typename TResult, typename TSource, typename TMapper> |
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131 SequenceMappingIterator<TResult, TSource, TMapper>::SequenceMappingIterator( |
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132 const TMapper &mapper, |
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133 const typename QAbstractXmlForwardIterator<TSource>::Ptr &iterator, |
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134 const DynamicContext::Ptr &context) |
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135 : m_position(0), |
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136 m_mainIterator(iterator), |
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137 m_context(context), |
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138 m_mapper(mapper) |
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139 { |
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140 Q_ASSERT(mapper); |
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141 Q_ASSERT(iterator); |
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142 } |
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143 |
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144 template<typename TResult, typename TSource, typename TMapper> |
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145 TResult SequenceMappingIterator<TResult, TSource, TMapper>::next() |
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146 { |
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147 /* This was once implemented with a recursive function, but the stack |
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148 * got blown for some inputs by that approach. */ |
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149 while(true) |
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150 { |
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151 while(!m_currentIterator) |
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152 { |
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153 const TSource mainItem(m_mainIterator->next()); |
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154 |
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155 if(qIsForwardIteratorEnd(mainItem)) /* We've reached the very end. */ |
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156 { |
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157 m_position = -1; |
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158 m_current = TResult(); |
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159 return TResult(); |
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160 } |
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161 else |
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162 m_currentIterator = m_mapper->mapToSequence(mainItem, m_context); |
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163 } |
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164 |
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165 m_current = m_currentIterator->next(); |
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166 |
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167 if(qIsForwardIteratorEnd(m_current)) |
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168 { |
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169 m_currentIterator.reset(); |
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170 continue; |
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171 } |
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172 else |
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173 { |
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174 ++m_position; |
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175 return m_current; |
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176 } |
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177 } |
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178 } |
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179 |
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180 template<typename TResult, typename TSource, typename TMapper> |
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181 xsInteger SequenceMappingIterator<TResult, TSource, TMapper>::count() |
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182 { |
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183 TSource unit(m_mainIterator->next()); |
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184 xsInteger c = 0; |
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185 |
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186 while(!qIsForwardIteratorEnd(unit)) |
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187 { |
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188 const typename QAbstractXmlForwardIterator<TResult>::Ptr sit(m_mapper->mapToSequence(unit, m_context)); |
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189 c += sit->count(); |
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190 unit = m_mainIterator->next(); |
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191 } |
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192 |
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193 return c; |
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194 } |
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195 |
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196 template<typename TResult, typename TSource, typename TMapper> |
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197 TResult SequenceMappingIterator<TResult, TSource, TMapper>::current() const |
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198 { |
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199 return m_current; |
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200 } |
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201 |
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202 template<typename TResult, typename TSource, typename TMapper> |
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203 xsInteger SequenceMappingIterator<TResult, TSource, TMapper>::position() const |
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204 { |
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205 return m_position; |
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206 } |
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207 |
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208 |
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209 /** |
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210 * @short An object generator for SequenceMappingIterator. |
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211 * |
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212 * makeSequenceMappingIterator() is a convenience function for avoiding specifying |
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213 * the full template instantiation for SequenceMappingIterator. Conceptually, it |
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214 * is identical to Qt's qMakePair(). |
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215 * |
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216 * @returns a SequenceMappingIterator wrapped in a smart pointer, that has been |
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217 * passed the constructor arguments @p mapper, @p source, and @p context. |
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218 * @see makeMappingCallbackPtr() |
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219 * @relates QAbstractXmlForwardIterator |
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220 */ |
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221 template<typename TResult, typename TSource, typename TMapper> |
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222 static inline |
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223 typename QAbstractXmlForwardIterator<TResult>::Ptr |
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224 makeSequenceMappingIterator(const TMapper &mapper, |
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225 const QExplicitlySharedDataPointer<QAbstractXmlForwardIterator<TSource> > &source, |
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226 const DynamicContext::Ptr &context) |
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227 { |
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228 return typename QAbstractXmlForwardIterator<TResult>::Ptr |
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229 (new SequenceMappingIterator<TResult, TSource, TMapper>(mapper, source, context)); |
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230 } |
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231 } |
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232 |
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233 QT_END_NAMESPACE |
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234 |
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235 QT_END_HEADER |
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236 |
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237 #endif |