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39
40
41
42#include "qcachingiterator_p.h"
43
44QT_BEGIN_NAMESPACE
45
46using namespace QPatternist;
47
48CachingIterator::CachingIterator(ItemSequenceCacheCell::Vector &cacheCells,
49 const VariableSlotID slot,
50 const DynamicContext::Ptr &context) : m_position(0),
51 m_varSlot(slot),
52 m_context(context),
53 m_cacheCells(cacheCells),
54 m_usingCache(true)
55{
56 Q_ASSERT(m_varSlot > -1);
57 Q_ASSERT(m_context);
58 Q_ASSERT(m_cacheCells.at(m_varSlot).sourceIterator);
59 Q_ASSERT_X((m_cacheCells.at(m_varSlot).cachedItems.isEmpty() && m_cacheCells.at(m_varSlot).cacheState == ItemSequenceCacheCell::Empty) ||
60 m_cacheCells.at(m_varSlot).cacheState == ItemSequenceCacheCell::PartiallyPopulated,
61 Q_FUNC_INFO,
62 "It makes no sense to construct a CachingIterator for a cache that is ItemSequenceCacheCell::Full.");
63}
64
65Item CachingIterator::next()
66{
67 ItemSequenceCacheCell &cell = m_cacheCells[m_varSlot];
68 if(m_position == -1)
69 return Item();
70
71 if(m_usingCache)
72 {
73 ++m_position;
74
75 /* QAbstractXmlForwardIterator::position() starts at 1, while Qt's container classes
76 * starts at 0. */
77 if(m_position - 1 < cell.cachedItems.count())
78 {
79 m_current = cell.cachedItems.at(i: m_position - 1);
80 return m_current;
81 }
82 else
83 {
84 cell.cacheState = ItemSequenceCacheCell::PartiallyPopulated;
85 m_usingCache = false;
86 /* We decrement here so we don't have to add a branch for this
87 * when using the source QAbstractXmlForwardIterator below. */
88 --m_position;
89 }
90 }
91
92 m_current = cell.sourceIterator->next();
93
94 if(m_current)
95 {
96 cell.cachedItems.append(t: m_current);
97 Q_ASSERT(cell.cacheState == ItemSequenceCacheCell::PartiallyPopulated);
98 ++m_position;
99 return m_current;
100 }
101 else
102 {
103 m_position = -1;
104 cell.cacheState = ItemSequenceCacheCell::Full;
105 return Item();
106 }
107}
108
109Item CachingIterator::current() const
110{
111 return m_current;
112}
113
114xsInteger CachingIterator::position() const
115{
116 return m_position;
117}
118
119Item::Iterator::Ptr CachingIterator::copy() const
120{
121 const ItemSequenceCacheCell &cell = m_cacheCells.at(i: m_varSlot);
122 if(cell.cacheState == ItemSequenceCacheCell::Full)
123 return makeListIterator(list: cell.cachedItems);
124 else
125 return Item::Iterator::Ptr(new CachingIterator(m_cacheCells, m_varSlot, m_context));
126}
127
128QT_END_NAMESPACE
129

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source code of qtxmlpatterns/src/xmlpatterns/iterators/qcachingiterator.cpp