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46 // This file is not part of the Qt API. It exists purely as an
47 // implementation detail. This header file may change from version to
48 // version without notice, or even be removed.
52 #ifndef Patternist_GenericPredicate_H
53 #define Patternist_GenericPredicate_H
55 #include <private/qpaircontainer_p.h>
64 * @short A predicate that can handle all kinds of predicates and
65 * is therefore not very efficient, but can cope with all the tricky scenarios.
67 * @see FirstItemPredicate
69 * @author Frans Englich <frans.englich@nokia.com>
70 * @ingroup Patternist_expressions
72 class GenericPredicate : public PairContainer
77 * Creates a predicate expression that filters the items gained
78 * from evaluating @p sourceExpression through the filter @p predicateExpression.
80 * This function performs type analyzis on the passed expressions, and may
81 * return more specialized expressions depending on the analyzis.
83 * If @p predicateExpression is an invalid predicate, an error is issued
86 static Expression::Ptr create(const Expression::Ptr &sourceExpression,
87 const Expression::Ptr &predicateExpression,
88 const StaticContext::Ptr &context,
89 const QSourceLocation &location);
91 static Expression::Ptr createFirstItem(const Expression::Ptr &sourceExpression);
94 * Creates a source iterator which is passed to the ItemMappingIterator
95 * and the Focus. The ItemMappingIterator modifies it with
96 * its QAbstractXmlForwardIterator::next() calls, and since the Focus references the same QAbstractXmlForwardIterator,
97 * the focus is automatically moved.
99 virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;
102 * Doesn't return the first item from calling evaluateSequence(), but does the mapping
103 * manually. This avoid allocating an ItemMappingIterator.
105 virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;
107 inline Item mapToItem(const Item &subject,
108 const DynamicContext::Ptr &) const;
110 virtual SequenceType::List expectedOperandTypes() const;
111 virtual SequenceType::Ptr staticType() const;
112 virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;
113 virtual ID id() const;
116 * @returns always CreatesFocusForLast.
118 virtual Properties properties() const;
120 virtual QString description() const;
125 * Creates a GenericPredicate which filters the items from the @p sourceExpression
126 * through @p predicate.
128 * This constructor is protected. The proper way to create predicates is via the static
131 GenericPredicate(const Expression::Ptr &sourceExpression,
132 const Expression::Ptr &predicate);
135 * @returns the ItemType of the first operand's staticType().
137 virtual ItemType::Ptr newFocusType() const;
140 typedef QExplicitlySharedDataPointer<const GenericPredicate> ConstPtr;