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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_TreatAs_H |
51 | #define Patternist_TreatAs_H |
52 | |
53 | #include <private/qsinglecontainer_p.h> |
54 | |
55 | QT_BEGIN_NAMESPACE |
56 | |
57 | namespace QPatternist |
58 | { |
59 | /** |
60 | * @short Implements XPath 2.0's <tt>treat as</tt> expression. |
61 | * |
62 | * TreatAs is always a compile-time class only, and is always deallocated |
63 | * by re-writing to CardinalityVerifier or ItemVerifier or both, by calling |
64 | * TypeChecker::applyFunctionConversion(). |
65 | * |
66 | * |
67 | * One approach could be to skip instantiating TreatAs and simply let the |
68 | * return value of TypeChecker::applyFunctionConversion() be inserted into |
69 | * the AST, but that wouldn't handle type checking the context item |
70 | * properly, which depends on that the StaticContext have been set by the |
71 | * parent Expression. |
72 | * |
73 | * @see <a href="http://www.w3.org/TR/xpath20/#id-treat">XML Path Language |
74 | * (XPath) 2.0, 3.10.5 Treat</a> |
75 | * @author Frans Englich <frans.englich@nokia.com> |
76 | * @ingroup Patternist_expressions |
77 | */ |
78 | class TreatAs : public SingleContainer |
79 | { |
80 | public: |
81 | /** |
82 | * Creats a TreatAs where it is checked that the expression @p operand conforms |
83 | * to the type @p reqType. |
84 | */ |
85 | TreatAs(const Expression::Ptr &operand, |
86 | const SequenceType::Ptr &reqType); |
87 | |
88 | /** |
89 | * This function rewrites always. First the type that this TreatAs expression tests for |
90 | * is verified. Then, the type the <tt>treat as</tt> expression itself must match, @p reqType, |
91 | * is verified. |
92 | */ |
93 | virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context, |
94 | const SequenceType::Ptr &reqType); |
95 | |
96 | /** |
97 | * @returns always the SequenceType passed in the constructor to this class. That is, the |
98 | * SequenceType that the operand must conform to. |
99 | */ |
100 | virtual SequenceType::Ptr staticType() const; |
101 | |
102 | /** |
103 | * @returns a list containing one CommonSequenceTypes::ZeroOrMoreItems |
104 | */ |
105 | virtual SequenceType::List expectedOperandTypes() const; |
106 | |
107 | virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; |
108 | |
109 | private: |
110 | const SequenceType::Ptr m_reqType; |
111 | }; |
112 | } |
113 | |
114 | QT_END_NAMESPACE |
115 | |
116 | #endif |
117 | |