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_EmptyContainer_H
51#define Patternist_EmptyContainer_H
52
53#include <private/qexpression_p.h>
54
55QT_BEGIN_NAMESPACE
56
57namespace QPatternist
58{
59 /**
60 * @short Base class for expressions that has no operands.
61 *
62 * @author Frans Englich <frans.englich@nokia.com>
63 * @ingroup Patternist_expressions
64 */
65 class Q_AUTOTEST_EXPORT EmptyContainer : public Expression
66 {
67 public:
68 /**
69 * @returns always an empty list.
70 */
71 virtual Expression::List operands() const;
72
73 /**
74 * Does nothing, since sub-classes has no operands. Calling
75 * it makes hence no sense, and it also results in an assert crash.
76 */
77 virtual void setOperands(const Expression::List &);
78
79 protected:
80 /**
81 * @returns always @c true
82 */
83 virtual bool compressOperands(const StaticContext::Ptr &context);
84
85 /**
86 * @returns always an empty list since it has no operands.
87 */
88 virtual SequenceType::List expectedOperandTypes() const;
89
90 };
91}
92
93QT_END_NAMESPACE
94
95#endif
96

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