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 QtCore 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#ifndef QSCOPEDVALUEROLLBACK_H
41#define QSCOPEDVALUEROLLBACK_H
42
43#include <QtCore/qglobal.h>
44
45QT_BEGIN_NAMESPACE
46
47template <typename T>
48class [[nodiscard]] QScopedValueRollback
49{
50public:
51 explicit constexpr QScopedValueRollback(T &var)
52 : varRef(var), oldValue(var)
53 {
54 }
55
56 explicit constexpr QScopedValueRollback(T &var, T value)
57 : varRef(var), oldValue(qExchange(var, std::move(value)))
58 {
59 }
60
61#if __cpp_constexpr >= 201907L
62 constexpr
63#endif
64 ~QScopedValueRollback()
65 {
66 varRef = std::move(oldValue);
67 }
68
69 constexpr void commit()
70 {
71 oldValue = varRef;
72 }
73
74private:
75 T &varRef;
76 T oldValue;
77
78 Q_DISABLE_COPY(QScopedValueRollback)
79};
80
81QT_END_NAMESPACE
82
83#endif // QSCOPEDVALUEROLLBACK_H
84