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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_DistinctIterator_H
53 #define Patternist_DistinctIterator_H
57 #include <private/qexpression_p.h>
58 #include <private/qitem_p.h>
59 #include <private/qatomiccomparator_p.h>
60 #include <private/qcomparisonplatform_p.h>
61 #include <private/qsourcelocationreflection_p.h>
71 * @short Filters another sequence by removing duplicates such that the items are unique.
73 * DistinctIterator takes an input sequence, and returns a sequence where each
74 * item is unique. Thus, DistinctIterator removes the duplicates of items
75 * in a sequence. DistinctIterator is central in the implementation of the
76 * <tt>fn:distinct-values()</tt> function.
78 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-distinct-values">XQuery 1.0
79 * and XPath 2.0 Functions and Operators, 15.1.6 fn:distinct-values</a>
80 * @author Frans Englich <frans.englich@nokia.com>
81 * @ingroup Patternist_iterators
83 class DistinctIterator : public Item::Iterator
84 , public ComparisonPlatform<DistinctIterator, false>
85 , public SourceLocationReflection
89 * Creates a DistinctIterator.
90 * @param comp the AtomicComparator to be used for comparing values. This may be @c null,
91 * meaning the IndexOfIterator iterator will dynamically determine what comparator to use
92 * @param seq the sequence whose duplicates should be filtered out
93 * @param context the usual context, used for error reporting and by AtomicComparators.
94 * @param expression the Expression that this DistinctIterator is
95 * evaluating for. It is used for error reporting, via
98 DistinctIterator(const Item::Iterator::Ptr &seq,
99 const AtomicComparator::Ptr &comp,
100 const Expression::ConstPtr &expression,
101 const DynamicContext::Ptr &context);
104 virtual Item current() const;
105 virtual xsInteger position() const;
106 virtual Item::Iterator::Ptr copy() const;
107 virtual const SourceLocationReflection *actualReflection() const;
109 inline AtomicComparator::Operator operatorID() const
111 return AtomicComparator::OperatorEqual;
115 const Item::Iterator::Ptr m_seq;
116 const DynamicContext::Ptr m_context;
117 const Expression::ConstPtr m_expr;
119 xsInteger m_position;
120 Item::List m_processed;