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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_SubsequenceIterator_H
51#define Patternist_SubsequenceIterator_H
52
53#include <private/qitem_p.h>
54
55QT_BEGIN_NAMESPACE
56
57namespace QPatternist
58{
59 /**
60 * @short Picks out a slice from another QAbstractXmlForwardIterator, specified by a start and end position.
61 *
62 * SubsequenceIterator allows a "slice", a subsequence, from an QAbstractXmlForwardIterator to
63 * be extracted. The SubsequenceIterator's constructor takes a source QAbstractXmlForwardIterator,
64 * a start position, and the length of the subsequence to be extracted.
65 *
66 * SubsequenceIterator contains the central business logic to implement
67 * the <tt>fn:subsequence()</tt> function. The detailed behavior, such as how it behaves
68 * if the source QAbstractXmlForwardIterator is empty or if the specified subsequence stretches
69 * beyond the source QAbstractXmlForwardIterator, is therefore consistent with the definition of
70 * the <tt>fn:subsequence()</tt> function.
71 *
72 * @see <a href="http://www.w3.org/TR/xpath-functions/#func-subsequence">XQuery 1.0
73 * and XPath 2.0 Functions and Operators, 15.1.10 fn:subsequence</a>
74 * @author Frans Englich <frans.englich@nokia.com>
75 * @ingroup Patternist_iterators
76 */
77 class SubsequenceIterator : public Item::Iterator
78 {
79 public:
80 /**
81 * Creates a SubsequenceIterator that extracts a subsequence from the sequence
82 * in @p iterator, as specified by the @p start position and @p length parameter.
83 *
84 * @param iterator the iterator which the subsequence should
85 * be extracted from
86 * @param start the start position of extraction. Must be 1 or larger.
87 * @param length the length of the subsequence to extract. If it is
88 * -1, to the end is returned. The value must be -1 or 1 or larger.
89 */
90 SubsequenceIterator(const Item::Iterator::Ptr &iterator,
91 const xsInteger start,
92 const xsInteger length);
93
94 virtual Item next();
95 virtual Item current() const;
96 virtual xsInteger position() const;
97 virtual Item::Iterator::Ptr copy() const;
98
99 private:
100 xsInteger m_position;
101 Item m_current;
102 const Item::Iterator::Ptr m_it;
103 xsInteger m_counter;
104 const xsInteger m_start;
105 const xsInteger m_len;
106 const xsInteger m_stop;
107 };
108}
109
110QT_END_NAMESPACE
111
112#endif
113

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