1// Copyright (C) 2023 The Qt Company Ltd.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3
4#if 0
5#pragma qt_sync_skip_header_check
6#pragma qt_sync_stop_processing
7#endif
8
9#ifndef QFUNCTIONALTOOLS_IMPL_H
10#define QFUNCTIONALTOOLS_IMPL_H
11
12#include <QtCore/qtconfigmacros.h>
13
14#include <type_traits>
15#include <utility>
16
17QT_BEGIN_NAMESPACE
18
19namespace QtPrivate {
20
21namespace detail {
22
23#define FOR_EACH_CVREF(op) \
24 op(&) \
25 op(const &) \
26 op(&&) \
27 op(const &&) \
28 /* end */
29
30
31template <typename Object, typename = void>
32struct StorageByValue
33{
34 Object o;
35#define MAKE_GETTER(cvref) \
36 constexpr Object cvref object() cvref noexcept \
37 { return static_cast<Object cvref>(o); }
38 FOR_EACH_CVREF(MAKE_GETTER)
39#undef MAKE_GETTER
40};
41
42template <typename Object, typename Tag = void>
43struct StorageEmptyBaseClassOptimization : Object
44{
45 StorageEmptyBaseClassOptimization() = default;
46 StorageEmptyBaseClassOptimization(Object &&o)
47 : Object(std::move(o))
48 {}
49 StorageEmptyBaseClassOptimization(const Object &o)
50 : Object(o)
51 {}
52
53#define MAKE_GETTER(cvref) \
54 constexpr Object cvref object() cvref noexcept \
55 { return static_cast<Object cvref>(*this); }
56 FOR_EACH_CVREF(MAKE_GETTER)
57#undef MAKE_GETTER
58};
59} // namespace detail
60
61template <typename Object, typename Tag = void>
62using CompactStorage = typename std::conditional_t<
63 std::conjunction_v<
64 std::is_empty<Object>,
65 std::negation<std::is_final<Object>>
66 >,
67 detail::StorageEmptyBaseClassOptimization<Object, Tag>,
68 detail::StorageByValue<Object, Tag>
69 >;
70
71} // namespace QtPrivate
72
73#undef FOR_EACH_CVREF
74
75QT_END_NAMESPACE
76
77#endif // QFUNCTIONALTOOLS_IMPL_H
78