1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___TYPE_TRAITS_IS_SWAPPABLE_H
10#define _LIBCPP___TYPE_TRAITS_IS_SWAPPABLE_H
11
12#include <__config>
13#include <__type_traits/add_lvalue_reference.h>
14#include <__type_traits/conditional.h>
15#include <__type_traits/enable_if.h>
16#include <__type_traits/is_move_assignable.h>
17#include <__type_traits/is_move_constructible.h>
18#include <__type_traits/is_nothrow_move_assignable.h>
19#include <__type_traits/is_nothrow_move_constructible.h>
20#include <__type_traits/is_referenceable.h>
21#include <__type_traits/is_same.h>
22#include <__type_traits/is_void.h>
23#include <__type_traits/nat.h>
24#include <__utility/declval.h>
25#include <cstddef>
26
27#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
28#  pragma GCC system_header
29#endif
30
31_LIBCPP_BEGIN_NAMESPACE_STD
32
33template <class _Tp>
34struct __is_swappable;
35template <class _Tp>
36struct __is_nothrow_swappable;
37
38#ifndef _LIBCPP_CXX03_LANG
39template <class _Tp>
40using __swap_result_t = __enable_if_t<is_move_constructible<_Tp>::value && is_move_assignable<_Tp>::value>;
41#else
42template <class>
43using __swap_result_t = void;
44#endif
45
46template <class _Tp>
47inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __swap_result_t<_Tp> swap(_Tp& __x, _Tp& __y)
48    _NOEXCEPT_(is_nothrow_move_constructible<_Tp>::value&& is_nothrow_move_assignable<_Tp>::value);
49
50template <class _Tp, size_t _Np, __enable_if_t<__is_swappable<_Tp>::value, int> = 0>
51inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np])
52    _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value);
53
54namespace __detail {
55// ALL generic swap overloads MUST already have a declaration available at this point.
56
57template <class _Tp, class _Up = _Tp, bool _NotVoid = !is_void<_Tp>::value && !is_void<_Up>::value>
58struct __swappable_with {
59  template <class _LHS, class _RHS>
60  static decltype(swap(std::declval<_LHS>(), std::declval<_RHS>())) __test_swap(int);
61  template <class, class>
62  static __nat __test_swap(long);
63
64  // Extra parens are needed for the C++03 definition of decltype.
65  typedef decltype((__test_swap<_Tp, _Up>(0))) __swap1;
66  typedef decltype((__test_swap<_Up, _Tp>(0))) __swap2;
67
68  static const bool value = _IsNotSame<__swap1, __nat>::value && _IsNotSame<__swap2, __nat>::value;
69};
70
71template <class _Tp, class _Up>
72struct __swappable_with<_Tp, _Up, false> : false_type {};
73
74template <class _Tp, class _Up = _Tp, bool _Swappable = __swappable_with<_Tp, _Up>::value>
75struct __nothrow_swappable_with {
76  static const bool value =
77#ifndef _LIBCPP_HAS_NO_NOEXCEPT
78      noexcept(swap(std::declval<_Tp>(), std::declval<_Up>()))&& noexcept(
79          swap(std::declval<_Up>(), std::declval<_Tp>()));
80#else
81      false;
82#endif
83};
84
85template <class _Tp, class _Up>
86struct __nothrow_swappable_with<_Tp, _Up, false> : false_type {};
87
88} // namespace __detail
89
90template <class _Tp>
91struct __is_swappable : public integral_constant<bool, __detail::__swappable_with<_Tp&>::value> {};
92
93template <class _Tp>
94struct __is_nothrow_swappable : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp&>::value> {};
95
96#if _LIBCPP_STD_VER >= 17
97
98template <class _Tp, class _Up>
99struct _LIBCPP_TEMPLATE_VIS is_swappable_with
100    : public integral_constant<bool, __detail::__swappable_with<_Tp, _Up>::value> {};
101
102template <class _Tp>
103struct _LIBCPP_TEMPLATE_VIS is_swappable
104    : public __conditional_t<__libcpp_is_referenceable<_Tp>::value,
105                             is_swappable_with<__add_lvalue_reference_t<_Tp>, __add_lvalue_reference_t<_Tp> >,
106                             false_type> {};
107
108template <class _Tp, class _Up>
109struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable_with
110    : public integral_constant<bool, __detail::__nothrow_swappable_with<_Tp, _Up>::value> {};
111
112template <class _Tp>
113struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable
114    : public __conditional_t<__libcpp_is_referenceable<_Tp>::value,
115                             is_nothrow_swappable_with<__add_lvalue_reference_t<_Tp>, __add_lvalue_reference_t<_Tp> >,
116                             false_type> {};
117
118template <class _Tp, class _Up>
119inline constexpr bool is_swappable_with_v = is_swappable_with<_Tp, _Up>::value;
120
121template <class _Tp>
122inline constexpr bool is_swappable_v = is_swappable<_Tp>::value;
123
124template <class _Tp, class _Up>
125inline constexpr bool is_nothrow_swappable_with_v = is_nothrow_swappable_with<_Tp, _Up>::value;
126
127template <class _Tp>
128inline constexpr bool is_nothrow_swappable_v = is_nothrow_swappable<_Tp>::value;
129
130#endif // _LIBCPP_STD_VER >= 17
131
132_LIBCPP_END_NAMESPACE_STD
133
134#endif // _LIBCPP___TYPE_TRAITS_IS_SWAPPABLE_H
135