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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_CastingPlatform_H |
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53 #define Patternist_CastingPlatform_H |
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54 |
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55 #include "qatomiccasterlocator_p.h" |
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56 #include "qatomiccaster_p.h" |
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57 #include "qatomicstring_p.h" |
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58 #include "qatomictype_p.h" |
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59 #include "qbuiltintypes_p.h" |
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60 #include "qcommonsequencetypes_p.h" |
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61 #include "qpatternistlocale_p.h" |
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62 #include "qqnamevalue_p.h" |
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63 #include "qschematypefactory_p.h" |
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64 #include "qstaticcontext_p.h" |
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65 #include "qvalidationerror_p.h" |
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66 |
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67 QT_BEGIN_HEADER |
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68 |
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69 QT_BEGIN_NAMESPACE |
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70 |
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71 namespace QPatternist |
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72 { |
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73 /** |
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74 * @short Provides casting functionality for classes, such as CastAs or NumberFN, which |
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75 * needs to perform casting. |
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76 * |
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77 * Classes which need to perform casting can simply from this class and gain |
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78 * access to casting functinality wrapped in a convenient way. At the center of this |
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79 * class is the cast() function, which is used at runtime to perform the actual cast. |
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80 * |
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81 * The actual circumstances where casting is used, such as in the 'castable as' |
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82 * expression or the <tt>fn:number()</tt> function, often have other things to handle as well, |
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83 * error handling and cardinality checks for example. This class handles only casting |
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84 * and leaves the other case-specific details to the sub-class such that this class only |
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85 * do one thing well. |
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86 * |
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87 * This template class takes two parameters: |
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88 * - TSubClass This should be the class inheriting from CastingPlatform. |
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89 * - issueError if true, errors are issued via ReportContext, otherwise |
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90 * ValidationError instances are returned appropriately. |
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91 * |
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92 * The class inheriting CastingPlatform must implement the following function: |
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93 * @code |
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94 * ItemType::Ptr targetType() const |
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95 * @endcode |
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96 * |
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97 * that returns the type that should be cast to. The type must be an AtomicType. |
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98 * Typically, it is appropriate to declare this function @c inline. |
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99 * |
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100 * A sub-class calls prepareCasting() at compile time(such that CastingPlatform can attempt |
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101 * to lookup the proper AtomicCaster) and then it simply uses the cast() function at runtime. The |
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102 * function targetType() must be implemented such that CastingPlatform knows |
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103 * what type it shall cast to. |
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104 * |
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105 * @see ValueFactory |
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106 * @author Frans Englich <frans.englich@nokia.com> |
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107 * @ingroup Patternist_expressions |
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108 */ |
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109 template<typename TSubClass, const bool issueError> |
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110 class CastingPlatform |
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111 { |
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112 protected: |
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113 /** |
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114 * @note issueCastError() depends on the default value. |
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115 */ |
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116 inline CastingPlatform(const ReportContext::ErrorCode code = ReportContext::FORG0001) : m_errorCode(code) |
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117 { |
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118 } |
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119 |
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120 /** |
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121 * Attempts to cast @p sourceValue to targetType(), and returns |
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122 * the created value. Remember that prepareCasting() should have been |
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123 * called at compile time, otherwise this function will be slow. |
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124 * |
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125 * Error reporting is done in two ways. If a cast fails because |
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126 * of an error in lexical representation a ValidationError is returned. |
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127 * If the cause of failure is that the casting combination is invalid(such as |
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128 * when attempting to cast @c xs:date to @c xs:integer), a ValidationError |
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129 * is returned if @c false was passed in the template instantiation, |
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130 * an error is issued via @p context. |
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131 * |
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132 * @param sourceValue the value to cast. Must be non @c null. |
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133 * @param context the usual ReportContext, used for error reporting. |
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134 * @returns the new value which was the result of the cast. If the |
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135 * cast failed, an ValidationError is returned. |
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136 */ |
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137 Item cast(const Item &sourceValue, |
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138 const ReportContext::Ptr &context) const; |
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139 |
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140 /** |
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141 * This function should be called at compiled time, it attempts to determine |
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142 * what AtomicCaster that should be used when casting from @p sourceType to |
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143 * targetType(). If that is not possible, because the @p sourceType is |
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144 * @c xs:anyAtomicType for instance, the AtomicCaster lookup will done at |
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145 * runtime on a case-per-case basis. |
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146 * |
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147 * @returns @c true if the requested casting combination is valid or might be valid. |
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148 * If it is guranteed to be invalid, @c false is returned. |
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149 */ |
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150 bool prepareCasting(const ReportContext::Ptr &context, |
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151 const ItemType::Ptr &sourceType); |
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152 |
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153 /** |
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154 * Checks that the targetType() is a valid target type for <tt>castable as</tt> |
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155 * and <tt>cast as</tt>. For example, that it is not abstract. If the type is |
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156 * invalid, an error is raised via the @p context. Note that it is assumed the type |
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157 * is atomic. |
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158 */ |
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159 void checkTargetType(const ReportContext::Ptr &context) const; |
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160 |
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161 private: |
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162 inline Item castWithCaster(const Item &sourceValue, |
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163 const AtomicCaster::Ptr &caster, |
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164 const ReportContext::Ptr &context) const; |
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165 |
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166 /** |
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167 * Locates the caster for casting values of type @p sourceType to targetType(), if |
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168 * possible. |
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169 * |
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170 * @p castImpossible is not initialized. Initialize it to @c false. |
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171 */ |
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172 static AtomicCaster::Ptr locateCaster(const ItemType::Ptr &sourceType, |
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173 const ReportContext::Ptr &context, |
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174 bool &castImpossible, |
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175 const SourceLocationReflection *const location, |
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176 const ItemType::Ptr &targetType); |
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177 private: |
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178 inline Item castWithCaster(const Item &sourceValue, |
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179 const AtomicCaster::Ptr &caster, |
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180 const DynamicContext::Ptr &context) const; |
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181 |
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182 |
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183 inline ItemType::Ptr targetType() const |
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184 { |
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185 Q_ASSERT(static_cast<const TSubClass *>(this)->targetType()); |
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186 return static_cast<const TSubClass *>(this)->targetType(); |
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187 } |
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188 |
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189 void issueCastError(const Item &validationError, |
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190 const Item &sourceValue, |
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191 const ReportContext::Ptr &context) const; |
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192 |
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193 Q_DISABLE_COPY(CastingPlatform) |
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194 AtomicCaster::Ptr m_caster; |
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195 const ReportContext::ErrorCode m_errorCode; |
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196 }; |
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197 |
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198 #include "qcastingplatform.cpp" |
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199 |
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200 } |
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201 |
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202 QT_END_NAMESPACE |
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203 |
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204 QT_END_HEADER |
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205 |
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206 #endif |