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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_CastAs_H |
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53 #define Patternist_CastAs_H |
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54 |
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55 #include "qsinglecontainer_p.h" |
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56 #include "qcastingplatform_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 Implements XPath 2.0's <tt>cast as</tt> expression. |
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66 * |
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67 * Implements the casting expression, such as <tt>'3' cast as xs:integer</tt>. This class also |
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68 * implements constructor functions, which are created in the ConstructorFunctionsFactory. |
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69 * |
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70 * CastAs uses CastingPlatform for carrying out the actual casting. |
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71 * |
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72 * @see <a href="http://www.w3.org/TR/xpath-functions/#casting">XQuery 1.0 |
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73 * and XPath 2.0 Functions and Operators, 7 Casting</a> |
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74 * @see <a href="http://www.w3.org/TR/xpath20/#id-cast">XML Path Language |
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75 * (XPath) 2.0, 3.10.2 Cast</a> |
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76 * @author Frans Englich <frans.englich@nokia.com> |
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77 * @ingroup Patternist_expressions |
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78 */ |
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79 class CastAs : public SingleContainer, |
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80 public CastingPlatform<CastAs, true /* issueError */> |
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81 { |
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82 public: |
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83 |
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84 /** |
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85 * @todo Wrong/old documentation |
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86 * |
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87 * Creates a cast expression for the type @p name via the schema type |
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88 * factory @p factory. This function is used by parser when creating |
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89 * 'cast to' expressions, and the ConstructorFunctionsFactory, when creating |
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90 * constructor functions. |
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91 * |
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92 * @param targetType the type which the CastAs should cast to |
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93 * @param source the operand to evaluate and then cast from |
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94 */ |
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95 CastAs(const Expression::Ptr &source, |
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96 const SequenceType::Ptr &targetType); |
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97 |
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98 virtual Item evaluateSingleton(const DynamicContext::Ptr &) const; |
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99 |
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100 virtual SequenceType::List expectedOperandTypes() const; |
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101 |
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102 /** |
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103 * @returns a SequenceType where the ItemType is this CastAs's |
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104 * target type, as per targetType(), and the Cardinality is inferred from the |
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105 * source operand to reflect whether this CastAs always will evaluate to |
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106 * exactly-one or zero-or-one values. |
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107 */ |
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108 virtual SequenceType::Ptr staticType() const; |
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109 |
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110 /** |
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111 * Overridden in order to check that casting to an abstract type |
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112 * is not attempted. |
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113 */ |
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114 virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context, |
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115 const SequenceType::Ptr &reqType); |
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116 |
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117 /** |
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118 * If the target type is the same as the source type, it is rewritten |
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119 * to the operand. |
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120 */ |
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121 virtual Expression::Ptr compress(const StaticContext::Ptr &context); |
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122 virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; |
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123 |
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124 inline ItemType::Ptr targetType() const |
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125 { |
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126 return m_targetType->itemType(); |
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127 } |
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128 |
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129 inline SequenceType::Ptr targetSequenceType() const |
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130 { |
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131 return m_targetType; |
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132 } |
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133 |
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134 private: |
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135 /** |
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136 * Performs casting to @c xs:QName. This case is special, and is always done at compile time. |
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137 */ |
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138 Expression::Ptr castToQName(const StaticContext::Ptr &context) const; |
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139 |
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140 const SequenceType::Ptr m_targetType; |
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141 }; |
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142 } |
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143 |
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144 QT_END_NAMESPACE |
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145 |
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146 QT_END_HEADER |
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147 |
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148 #endif |