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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_DistinctIterator_H
51#define Patternist_DistinctIterator_H
52
53#include <QList>
54
55#include <private/qexpression_p.h>
56#include <private/qitem_p.h>
57#include <private/qatomiccomparator_p.h>
58#include <private/qcomparisonplatform_p.h>
59#include <private/qsourcelocationreflection_p.h>
60
61QT_BEGIN_NAMESPACE
62
63namespace QPatternist
64{
65
66 /**
67 * @short Filters another sequence by removing duplicates such that the items are unique.
68 *
69 * DistinctIterator takes an input sequence, and returns a sequence where each
70 * item is unique. Thus, DistinctIterator removes the duplicates of items
71 * in a sequence. DistinctIterator is central in the implementation of the
72 * <tt>fn:distinct-values()</tt> function.
73 *
74 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-distinct-values">XQuery 1.0
75 * and XPath 2.0 Functions and Operators, 15.1.6 fn:distinct-values</a>
76 * @author Frans Englich <frans.englich@nokia.com>
77 * @ingroup Patternist_iterators
78 */
79 class DistinctIterator : public Item::Iterator
80 , public ComparisonPlatform<DistinctIterator, false>
81 , public SourceLocationReflection
82 {
83 public:
84 /**
85 * Creates a DistinctIterator.
86 * @param comp the AtomicComparator to be used for comparing values. This may be @c null,
87 * meaning the IndexOfIterator iterator will dynamically determine what comparator to use
88 * @param seq the sequence whose duplicates should be filtered out
89 * @param context the usual context, used for error reporting and by AtomicComparators.
90 * @param expression the Expression that this DistinctIterator is
91 * evaluating for. It is used for error reporting, via
92 * actualReflection().
93 */
94 DistinctIterator(const Item::Iterator::Ptr &seq,
95 const AtomicComparator::Ptr &comp,
96 const Expression::ConstPtr &expression,
97 const DynamicContext::Ptr &context);
98
99 virtual Item next();
100 virtual Item current() const;
101 virtual xsInteger position() const;
102 virtual Item::Iterator::Ptr copy() const;
103 virtual const SourceLocationReflection *actualReflection() const;
104
105 inline AtomicComparator::Operator operatorID() const
106 {
107 return AtomicComparator::OperatorEqual;
108 }
109
110 private:
111 const Item::Iterator::Ptr m_seq;
112 const DynamicContext::Ptr m_context;
113 const Expression::ConstPtr m_expr;
114 Item m_current;
115 xsInteger m_position;
116 Item::List m_processed;
117 };
118}
119
120QT_END_NAMESPACE
121
122#endif
123

source code of qtxmlpatterns/src/xmlpatterns/iterators/qdistinctiterator_p.h