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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 | |