1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtXmlPatterns module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
#ifndef Patternist_OperandsIterator_H
#define Patternist_OperandsIterator_H
#include <QPair>
#include <QStack>
#include "qexpression_p.h"
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
namespace QPatternist
{
/**
* @short A helper class that iterates a tree of Expression instances. It
* is not a sub-class of QAbstractXmlForwardIterator.
*
* The OperandsIterator delivers all Expression instances that are children at any
* depth of the Expression passed in the constructor.
* The order is delivered in a defined way, from left to right and depth
* first.
*
* @author Frans Englich <frans.englich@nokia.com>
*/
class OperandsIterator
{
/**
* The second value, the int, is the current position in the first.
*/
typedef QPair<Expression::List, int> Level;
public:
enum TreatParent
{
ExcludeParent,
IncludeParent
};
/**
* if @p treatParent is @c IncludeParent, @p start is excluded.
*
* @p start must be a valid Expression.
*/
inline OperandsIterator(const Expression::Ptr &start,
const TreatParent treatParent)
{
Q_ASSERT(start);
if(treatParent == IncludeParent)
{
Expression::List l;
l.append(start);
m_exprs.push(qMakePair(l, -1));
}
m_exprs.push(qMakePair(start->operands(), -1));
}
/**
* @short Returns the current Expression and advances the iterator.
*
* If the end has been reached, a default constructed pointer is
* returned.
*
* We intentionally return by reference.
*/
inline Expression::Ptr next()
{
if(m_exprs.isEmpty())
return Expression::Ptr();
Level &lvl = m_exprs.top();
++lvl.second;
if(lvl.second == lvl.first.size())
{
/* Resume iteration above us. */
m_exprs.pop();
if(m_exprs.isEmpty())
return Expression::Ptr();
while(true)
{
Level &previous = m_exprs.top();
++previous.second;
if(previous.second < previous.first.count())
{
const Expression::Ptr &op = previous.first.at(previous.second);
m_exprs.push(qMakePair(op->operands(), -1));
return op;
}
else
{
// We have already reached the end of this level.
m_exprs.pop();
if(m_exprs.isEmpty())
return Expression::Ptr();
}
}
}
else
{
const Expression::Ptr &op = lvl.first.at(lvl.second);
m_exprs.push(qMakePair(op->operands(), -1));
return op;
}
}
/**
* Advances this iterator by the current expression and its operands.
*/
Expression::Ptr skipOperands()
{
if(m_exprs.isEmpty())
return Expression::Ptr();
Level &lvl = m_exprs.top();
++lvl.second;
if(lvl.second == lvl.first.size())
{
/* We've reached the end of this level, at least. */
m_exprs.pop();
}
return next();
}
private:
Q_DISABLE_COPY(OperandsIterator)
QStack<Level> m_exprs;
};
}
QT_END_NAMESPACE
QT_END_HEADER
#endif
|
