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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_TruthPredicate_H |
51 | #define Patternist_TruthPredicate_H |
52 | |
53 | #include <private/qgenericpredicate_p.h> |
54 | |
55 | QT_BEGIN_NAMESPACE |
56 | |
57 | namespace QPatternist |
58 | { |
59 | /** |
60 | * @short A predicate which is optimized for filter expressions that |
61 | * are of type @c xs:boolean. |
62 | * |
63 | * @author Frans Englich <frans.englich@nokia.com> |
64 | * @ingroup Patternist_expressions |
65 | */ |
66 | class TruthPredicate : public GenericPredicate |
67 | { |
68 | public: |
69 | /** |
70 | * Creates a TruthPredicate which filters the items from the @p sourceExpression |
71 | * through @p predicate. |
72 | * |
73 | * This constructor is protected. The proper way to create predicates is via the static |
74 | * create() function. |
75 | */ |
76 | TruthPredicate(const Expression::Ptr &sourceExpression, |
77 | const Expression::Ptr &predicate); |
78 | |
79 | inline Item mapToItem(const Item &item, const DynamicContext::Ptr &context) const |
80 | { |
81 | Q_ASSERT_X(false, Q_FUNC_INFO, "This is practically dead code because it never gets called in GenericPredicate, " |
82 | "which binds to its own mapToItem for completely legitime reasons." ); |
83 | if(m_operand2->evaluateEBV(context)) |
84 | return item; |
85 | else |
86 | return Item(); |
87 | } |
88 | |
89 | inline Item::Iterator::Ptr map(const Item &item, |
90 | const DynamicContext::Ptr &context) const |
91 | { |
92 | Q_ASSERT_X(false, Q_FUNC_INFO, "I don't expect this function to be called, for the same reasons as above." ); |
93 | if(m_operand2->evaluateEBV(context)) |
94 | return makeSingletonIterator(item); |
95 | else |
96 | return CommonValues::emptyIterator; |
97 | } |
98 | |
99 | virtual SequenceType::List expectedOperandTypes() const; |
100 | virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const; |
101 | }; |
102 | } |
103 | |
104 | QT_END_NAMESPACE |
105 | |
106 | #endif |
107 | |