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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 | |
61 | QT_BEGIN_NAMESPACE |
62 | |
63 | namespace 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 | |
120 | QT_END_NAMESPACE |
121 | |
122 | #endif |
123 | |