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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_ExternalVariableLoader_H |
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53 #define Patternist_ExternalVariableLoader_H |
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54 |
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55 #include "qitem_p.h" |
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56 #include "qsequencetype_p.h" |
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57 #include "qxmlname.h" |
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58 |
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59 QT_BEGIN_HEADER |
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60 |
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61 QT_BEGIN_NAMESPACE |
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62 |
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63 namespace QPatternist |
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64 { |
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65 class DynamicContext; |
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66 |
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67 /** |
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68 * @short Responsible for loading and declaring available external variables. |
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69 * |
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70 * An external variable in XQuery is a global variable that has been declared to receive |
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71 * its value from the XQuery implementation, as opposed to an initializing expression. Here |
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72 * is an example of a query with an external variable declaration, followed by a ordinary |
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73 * global variable: |
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74 * |
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75 * <tt> declare variable $theName external; |
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76 * declare variable $theName := "the value"; |
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77 * "And here's the query body(a string literal)"</tt> |
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78 * |
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79 * An external variable declaration can also specify a sequence type: |
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80 * |
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81 * <tt>declare variable $theName as xs:integer external;</tt> |
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82 * |
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83 * This class allows the user to supply the values to external variables. When |
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84 * an external variable declaration occur in the query, |
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85 * announceExternalVariable() is called. |
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86 * |
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87 * @ingroup Patternist_xdm |
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88 * @author Frans Englich <frans.englich@nokia.com> |
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89 */ |
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90 class Q_AUTOTEST_EXPORT ExternalVariableLoader : public QSharedData |
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91 { |
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92 public: |
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93 typedef QExplicitlySharedDataPointer<ExternalVariableLoader> Ptr; |
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94 inline ExternalVariableLoader() {} |
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95 |
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96 virtual ~ExternalVariableLoader(); |
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97 |
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98 /** |
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99 * Called when Patternist encounters an external variable in the query. It is guaranteed |
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100 * to be called once for each external variable appearing in a query module. |
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101 * |
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102 * @param name the name of the variable. Quaranteed to never be @c null. |
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103 * @param declaredType the type that the user declared the variable to be of. Whether |
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104 * this type matches the actual value of the variable or not is irrelevant. Patternist |
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105 * will do the necessary error handling based on the sequence type that is returned from |
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106 * this function. If the user didn't declare a type, the type is <tt>item()*</tt>(zero or |
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107 * more items). Quaranteed to never be @c null. |
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108 * @returns the sequence type of the value this ExternalVariableLoader actually supplies. However, |
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109 * if the ExternalVariableLoader knows it cannot supply a variable by this name, @c null should be |
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110 * returned. |
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111 */ |
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112 virtual SequenceType::Ptr announceExternalVariable(const QXmlName name, |
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113 const SequenceType::Ptr &declaredType); |
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114 |
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115 /** |
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116 * This function is called at runtime when the external variable by name @p name needs |
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117 * to be evaluated. It is not defined how many times this function will be called. It |
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118 * depends on aspects such as how the query was optimized. |
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119 * |
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120 * @param name the name of the variable. Quaranteed to never be @c null. |
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121 * @param context the DynamicContext. |
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122 * @returns the value of the variable. Remember that this value must match the |
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123 * sequence type returned from announceExternalVariable() for the same name. |
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124 */ |
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125 virtual Item::Iterator::Ptr evaluateSequence(const QXmlName name, |
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126 const QExplicitlySharedDataPointer<DynamicContext> &context); |
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127 |
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128 virtual Item evaluateSingleton(const QXmlName name, |
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129 const QExplicitlySharedDataPointer<DynamicContext> &context); |
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130 virtual bool evaluateEBV(const QXmlName name, |
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131 const QExplicitlySharedDataPointer<DynamicContext> &context); |
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132 }; |
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133 } |
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134 |
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135 QT_END_NAMESPACE |
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136 |
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137 QT_END_HEADER |
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138 |
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139 #endif |