1/****************************************************************************
2**
3** Copyright (C) 2016 The Qt Company Ltd.
4** Contact: https://www.qt.io/licensing/
5**
6** This file is part of the QtXmlPatterns module of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:LGPL$
9** Commercial License Usage
10** Licensees holding valid commercial Qt licenses may use this file in
11** accordance with the commercial license agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and The Qt Company. For licensing terms
14** and conditions see https://www.qt.io/terms-conditions. For further
15** information use the contact form at https://www.qt.io/contact-us.
16**
17** GNU Lesser General Public License Usage
18** Alternatively, this file may be used under the terms of the GNU Lesser
19** General Public License version 3 as published by the Free Software
20** Foundation and appearing in the file LICENSE.LGPL3 included in the
21** packaging of this file. Please review the following information to
22** ensure the GNU Lesser General Public License version 3 requirements
23** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
24**
25** GNU General Public License Usage
26** Alternatively, this file may be used under the terms of the GNU
27** General Public License version 2.0 or (at your option) the GNU General
28** Public license version 3 or any later version approved by the KDE Free
29** Qt Foundation. The licenses are as published by the Free Software
30** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
31** included in the packaging of this file. Please review the following
32** information to ensure the GNU General Public License requirements will
33** be met: https://www.gnu.org/licenses/gpl-2.0.html and
34** https://www.gnu.org/licenses/gpl-3.0.html.
35**
36** $QT_END_LICENSE$
37**
38****************************************************************************/
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_CacheCells_H
51#define Patternist_CacheCells_H
52
53#include <QList>
54#include <QVector>
55
56#include <private/qitem_p.h>
57
58QT_BEGIN_NAMESPACE
59
60namespace QPatternist
61{
62
63 /**
64 * @short Represents a cache entry for a single Item,
65 * as opposed to for a sequence of items.
66 *
67 * A characteristic of the ItemCacheCell is that it has two states:
68 * either its full or it's not, since it only deals with a single
69 * item.
70 *
71 * Remember that cachedItem doesn't tell the state of the ItemCacheCell.
72 * For instance, it can have a null pointer, the empty sequence, and that
73 * can be the value of its cache.
74 *
75 * @author Frans Englich <frans.englich@nokia.com>
76 */
77 class ItemCacheCell
78 {
79 public:
80 typedef QList<ItemCacheCell> List;
81 typedef QVector<ItemCacheCell> Vector;
82 enum CacheState
83 {
84 Full,
85 Empty
86 };
87
88 inline ItemCacheCell() : cacheState(Empty)
89 {
90 }
91
92 Item cachedItem;
93 CacheState cacheState;
94 };
95
96 /**
97 * @short Represents a cache entry for a sequence of items.
98 *
99 * As opposed to ItemCacheCell, ItemSequenceCacheCell can be partially
100 * populated: e.g, four items is in the cache while three remains in the
101 * source. For that reason ItemSequenceCacheCell in addition to the source
102 * also carried an QAbstractXmlForwardIterator which is the source, such
103 * that it can continue to populate the cache when it runs out.
104 *
105 * @author Frans Englich <frans.englich@nokia.com>
106 */
107 class ItemSequenceCacheCell
108 {
109 public:
110 typedef QList<ItemSequenceCacheCell> List;
111 typedef QVector<ItemSequenceCacheCell> Vector;
112
113 enum CacheState
114 {
115 Full,
116 Empty,
117 PartiallyPopulated
118 };
119
120 inline ItemSequenceCacheCell() : cacheState(Empty)
121 , inUse(false)
122 {
123 }
124
125 Item::List cachedItems;
126 Item::Iterator::Ptr sourceIterator;
127 CacheState cacheState;
128 /**
129 * In XSL-T, we can have circularity which we cannot detect statically.
130 * For instance, a global variable invokes a template, and the template
131 * uses the variable. We can't detect that, because we can't figure out
132 * what template will be invoked.
133 *
134 * For solution we have this toggle, which is set temporarily on the
135 * cell such that EvaluationCache can detect whether it's trashing
136 * itself.
137 *
138 * One might think that it would be sufficient to flag usage of the
139 * variable in an arbitrary template, but that would also flag valid
140 * cases.
141 */
142 bool inUse;
143 };
144}
145
146Q_DECLARE_TYPEINFO(QPatternist::ItemCacheCell, Q_MOVABLE_TYPE);
147Q_DECLARE_TYPEINFO(QPatternist::ItemSequenceCacheCell, Q_MOVABLE_TYPE);
148
149QT_END_NAMESPACE
150
151#endif
152

source code of qtxmlpatterns/src/xmlpatterns/expr/qcachecells_p.h