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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_TreatAs_H |
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53 #define Patternist_TreatAs_H |
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54 |
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55 #include "qsinglecontainer_p.h" |
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56 |
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57 QT_BEGIN_HEADER |
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58 |
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59 QT_BEGIN_NAMESPACE |
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60 |
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61 namespace QPatternist |
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62 { |
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63 /** |
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64 * @short Implements XPath 2.0's <tt>treat as</tt> expression. |
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65 * |
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66 * TreatAs is always a compile-time class only, and is always deallocated |
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67 * by re-writing to CardinalityVerifier or ItemVerifier or both, by calling |
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68 * TypeChecker::applyFunctionConversion(). |
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69 * |
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70 * |
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71 * One approach could be to skip instantiating TreatAs and simply let the |
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72 * return value of TypeChecker::applyFunctionConversion() be inserted into |
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73 * the AST, but that wouldn't handle type checking the context item |
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74 * properly, which depends on that the StaticContext have been set by the |
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75 * parent Expression. |
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76 * |
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77 * @see <a href="http://www.w3.org/TR/xpath20/#id-treat">XML Path Language |
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78 * (XPath) 2.0, 3.10.5 Treat</a> |
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79 * @author Frans Englich <frans.englich@nokia.com> |
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80 * @ingroup Patternist_expressions |
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81 */ |
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82 class TreatAs : public SingleContainer |
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83 { |
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84 public: |
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85 /** |
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86 * Creats a TreatAs where it is checked that the expression @p operand conforms |
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87 * to the type @p reqType. |
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88 */ |
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89 TreatAs(const Expression::Ptr &operand, |
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90 const SequenceType::Ptr &reqType); |
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91 |
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92 /** |
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93 * This function rewrites always. First the type that this TreatAs expression tests for |
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94 * is verified. Then, the type the <tt>treat as</tt> expression itself must match, @p reqType, |
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95 * is verified. |
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96 */ |
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97 virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context, |
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98 const SequenceType::Ptr &reqType); |
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99 |
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100 /** |
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101 * @returns always the SequenceType passed in the constructor to this class. That is, the |
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102 * SequenceType that the operand must conform to. |
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103 */ |
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104 virtual SequenceType::Ptr staticType() const; |
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105 |
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106 /** |
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107 * @returns a list containing one CommonSequenceTypes::ZeroOrMoreItems |
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108 */ |
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109 virtual SequenceType::List expectedOperandTypes() const; |
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110 |
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111 virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; |
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112 |
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113 private: |
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114 const SequenceType::Ptr m_reqType; |
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115 }; |
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116 } |
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117 |
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118 QT_END_NAMESPACE |
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119 |
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120 QT_END_HEADER |
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121 |
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122 #endif |