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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
55QT_BEGIN_NAMESPACE
56
57namespace 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
114QT_END_NAMESPACE
115
116#endif
117

source code of qtxmlpatterns/src/xmlpatterns/expr/qtreatas_p.h