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The licenses are as published by the Free Software 30 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 31 ** included in the packaging of this file. Please review the following 32 ** information to ensure the GNU General Public License requirements will 33 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and 34 ** https://www.gnu.org/licenses/gpl-3.0.html. 35 ** 36 ** $QT_END_LICENSE$ 37 ** 38 ****************************************************************************/ 39 40 // 41 // W A R N I N G 42 // ------------- 43 // 44 // This file is not part of the Qt API. It exists purely as an 45 // implementation detail. This header file may change from version to 46 // version without notice, or even be removed. 47 // 48 // We mean it. 49 50 #ifndef Patternist_TypeChecker_H 51 #define Patternist_TypeChecker_H 52 53 #include <private/qstaticcontext_p.h> 54 #include <private/qexpression_p.h> 55 56 QT_BEGIN_NAMESPACE 57 58 namespace QPatternist 59 { 60 /** 61 * @short Contains functions that applies Function Conversion Rules and other 62 * kinds of compile-time type checking tasks. 63 * 64 * @ingroup Patternist_types 65 * @author Frans Englich <frans.englich@nokia.com> 66 */ 67 class TypeChecker 68 { 69 public: 70 enum Option 71 { 72 /** 73 * @short When set, the function conversion rules are applied. 74 * 75 * For instance, this is type promotion and conversions from @c 76 * xs:untypedAtomic to @c xs:date. This is done for function calls, 77 * but not when binding an expression to a variable. 78 */ 79 AutomaticallyConvert = 1, 80 81 /** 82 * @short Whether the focus should be checked or not. 83 * 84 * Sometimes the focus is unknown at the time 85 * applyFunctionConversion() is called, and therefore it is 86 * of interest to post pone the check to later on. 87 */ 88 CheckFocus = 2, 89 90 /** 91 * When applyFunctionConversion() is passed AutomaticallyConvert 92 * and promotion is required, such as from @c xs:integer to 93 * @c xs:float, there will be no conversion performed, with the 94 * assumption that the receiver will call Numeric::toFloat() or 95 * similar. 96 * 97 * However, when GeneratePromotion is set, code will be generated 98 * that performs this conversion regardless of what any receiver 99 * do. 100 * 101 * This is useful in the case where one Expression only pipes the 102 * result of another. The only known case of that as of this 103 * writing is when UserFunctionCallsite evaluates its body. 104 */ 105 GeneratePromotion 106 }; 107 typedef QFlags<Option> Options; 108 109 /** 110 * @short Builds a pipeline of artificial AST nodes that ensures @p operand 111 * conforms to the type @p reqType by applying the Function 112 * Conversion Rules. 113 * 114 * This new Expression is returned, or, if no conversions were necessary, 115 * @p operand as it is. 116 * 117 * applyFunctionConversion() also performs various checks, such as if 118 * @p operand needs the focus and that the focus is defined in the 119 * @p context. These checks are largely guided by @p operand's 120 * Expression::properties(). 121 * 122 * @see <a href="http://www.w3.org/TR/xpath20/\#id-function-calls">XML Path 123 * Language (XPath) 2.0, 3.1.5 Function Calls</a>, more specifically the 124 * Function Conversion Rules 125 */ 126 static Expression::Ptr 127 applyFunctionConversion(const Expression::Ptr &operand, 128 const SequenceType::Ptr &reqType, 129 const StaticContext::Ptr &context, 130 const ReportContext::ErrorCode code = ReportContext::XPTY0004, 131 const Options = Options(AutomaticallyConvert | CheckFocus)); 132 private: 133 134 static inline Expression::Ptr typeCheck(Expression *const op, 135 const StaticContext::Ptr &context, 136 const SequenceType::Ptr &reqType); 137 /** 138 * @short Implements the type checking and promotion part of the Function Conversion Rules. 139 */ 140 static Expression::Ptr verifyType(const Expression::Ptr &operand, 141 const SequenceType::Ptr &reqSeqType, 142 const StaticContext::Ptr &context, 143 const ReportContext::ErrorCode code, 144 const Options options); 145 146 /** 147 * Determines whether type promotion is possible from one type to another. False 148 * is returned when a promotion is not possible or if a promotion is not needed(as when 149 * the types are identical), since that can be considered to not be type promotion. 150 * 151 * @returns @c true if @p fromType can be promoted to @p toType. 152 * @see <a href="http://www.w3.org/TR/xpath20/#promotion">XML Path Language 153 * (XPath) 2.0, B.1 Type Promotion</a> 154 */ 155 static bool promotionPossible(const ItemType::Ptr &fromType, 156 const ItemType::Ptr &toType, 157 const StaticContext::Ptr &context); 158 159 /** 160 * @short Centralizes a message-string to reduce work for translators 161 * and increase consistency. 162 */ 163 static inline QString wrongType(const NamePool::Ptr &np, 164 const ItemType::Ptr &reqType, 165 const ItemType::Ptr &opType); 166 167 /** 168 * No implementation is provided for this constructor. This class 169 * is not supposed to be instantiated. 170 */ 171 inline TypeChecker(); 172 173 Q_DISABLE_COPY(TypeChecker) 174 }; 175 } 176 177 QT_END_NAMESPACE 178 179 #endif 180