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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_TruthPredicate_H |
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53 #define Patternist_TruthPredicate_H |
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54 |
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55 #include "qgenericpredicate_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 A predicate which is optimized for filter expressions that |
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65 * are of type @c xs:boolean. |
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66 * |
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67 * @author Frans Englich <frans.englich@nokia.com> |
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68 * @ingroup Patternist_expressions |
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69 */ |
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70 class TruthPredicate : public GenericPredicate |
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71 { |
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72 public: |
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73 /** |
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74 * Creates a TruthPredicate which filters the items from the @p sourceExpression |
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75 * through @p predicate. |
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76 * |
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77 * This constructor is protected. The proper way to create predicates is via the static |
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78 * create() function. |
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79 */ |
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80 TruthPredicate(const Expression::Ptr &sourceExpression, |
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81 const Expression::Ptr &predicate); |
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82 |
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83 inline Item mapToItem(const Item &item, const DynamicContext::Ptr &context) const |
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84 { |
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85 Q_ASSERT_X(false, Q_FUNC_INFO, "This is practically dead code because it never gets called in GenericPredicate, " |
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86 "which binds to its own mapToItem for completely legitime reasons."); |
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87 if(m_operand2->evaluateEBV(context)) |
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88 return item; |
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89 else |
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90 return Item(); |
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91 } |
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92 |
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93 inline Item::Iterator::Ptr map(const Item &item, |
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94 const DynamicContext::Ptr &context) const |
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95 { |
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96 Q_ASSERT_X(false, Q_FUNC_INFO, "I don't expect this function to be called, for the same reasons as above."); |
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97 if(m_operand2->evaluateEBV(context)) |
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98 return makeSingletonIterator(item); |
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99 else |
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100 return CommonValues::emptyIterator; |
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101 } |
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102 |
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103 virtual SequenceType::List expectedOperandTypes() const; |
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104 virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; |
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105 }; |
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106 } |
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107 |
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108 QT_END_NAMESPACE |
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109 |
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110 QT_END_HEADER |
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111 |
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112 #endif |