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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_CastAs_H |
51 | #define Patternist_CastAs_H |
52 | |
53 | #include <private/qsinglecontainer_p.h> |
54 | #include <private/qcastingplatform_p.h> |
55 | |
56 | QT_BEGIN_NAMESPACE |
57 | |
58 | namespace QPatternist |
59 | { |
60 | /** |
61 | * @short Implements XPath 2.0's <tt>cast as</tt> expression. |
62 | * |
63 | * Implements the casting expression, such as <tt>'3' cast as xs:integer</tt>. This class also |
64 | * implements constructor functions, which are created in the ConstructorFunctionsFactory. |
65 | * |
66 | * CastAs uses CastingPlatform for carrying out the actual casting. |
67 | * |
68 | * @see <a href="http://www.w3.org/TR/xpath-functions/#casting">XQuery 1.0 |
69 | * and XPath 2.0 Functions and Operators, 7 Casting</a> |
70 | * @see <a href="http://www.w3.org/TR/xpath20/#id-cast">XML Path Language |
71 | * (XPath) 2.0, 3.10.2 Cast</a> |
72 | * @author Frans Englich <frans.englich@nokia.com> |
73 | * @ingroup Patternist_expressions |
74 | */ |
75 | class CastAs : public SingleContainer, |
76 | public CastingPlatform<CastAs, true /* issueError */> |
77 | { |
78 | public: |
79 | |
80 | /** |
81 | * @todo Wrong/old documentation |
82 | * |
83 | * Creates a cast expression for the type @p name via the schema type |
84 | * factory @p factory. This function is used by parser when creating |
85 | * 'cast to' expressions, and the ConstructorFunctionsFactory, when creating |
86 | * constructor functions. |
87 | * |
88 | * @param targetType the type which the CastAs should cast to |
89 | * @param source the operand to evaluate and then cast from |
90 | */ |
91 | CastAs(const Expression::Ptr &source, |
92 | const SequenceType::Ptr &targetType); |
93 | |
94 | virtual Item evaluateSingleton(const DynamicContext::Ptr &) const; |
95 | |
96 | virtual SequenceType::List expectedOperandTypes() const; |
97 | |
98 | /** |
99 | * @returns a SequenceType where the ItemType is this CastAs's |
100 | * target type, as per targetType(), and the Cardinality is inferred from the |
101 | * source operand to reflect whether this CastAs always will evaluate to |
102 | * exactly-one or zero-or-one values. |
103 | */ |
104 | virtual SequenceType::Ptr staticType() const; |
105 | |
106 | /** |
107 | * Overridden in order to check that casting to an abstract type |
108 | * is not attempted. |
109 | */ |
110 | virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context, |
111 | const SequenceType::Ptr &reqType); |
112 | |
113 | /** |
114 | * If the target type is the same as the source type, it is rewritten |
115 | * to the operand. |
116 | */ |
117 | virtual Expression::Ptr compress(const StaticContext::Ptr &context); |
118 | virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; |
119 | |
120 | inline ItemType::Ptr targetType() const |
121 | { |
122 | return m_targetType->itemType(); |
123 | } |
124 | |
125 | inline SequenceType::Ptr targetSequenceType() const |
126 | { |
127 | return m_targetType; |
128 | } |
129 | |
130 | private: |
131 | /** |
132 | * Performs casting to @c xs:QName. This case is special, and is always done at compile time. |
133 | */ |
134 | Expression::Ptr castToQName(const StaticContext::Ptr &context) const; |
135 | |
136 | const SequenceType::Ptr m_targetType; |
137 | }; |
138 | } |
139 | |
140 | QT_END_NAMESPACE |
141 | |
142 | #endif |
143 | |