1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___MEMORY_COMPRESSED_PAIR_H
11#define _LIBCPP___MEMORY_COMPRESSED_PAIR_H
12
13#include <__config>
14#include <__fwd/tuple.h>
15#include <__tuple/tuple_indices.h>
16#include <__type_traits/decay.h>
17#include <__type_traits/dependent_type.h>
18#include <__type_traits/enable_if.h>
19#include <__type_traits/is_constructible.h>
20#include <__type_traits/is_empty.h>
21#include <__type_traits/is_final.h>
22#include <__type_traits/is_same.h>
23#include <__type_traits/is_swappable.h>
24#include <__utility/forward.h>
25#include <__utility/move.h>
26#include <__utility/piecewise_construct.h>
27#include <cstddef>
28
29#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
30# pragma GCC system_header
31#endif
32
33_LIBCPP_PUSH_MACROS
34#include <__undef_macros>
35
36_LIBCPP_BEGIN_NAMESPACE_STD
37
38// Tag used to default initialize one or both of the pair's elements.
39struct __default_init_tag {};
40struct __value_init_tag {};
41
42template <class _Tp, int _Idx, bool _CanBeEmptyBase = is_empty<_Tp>::value && !__libcpp_is_final<_Tp>::value>
43struct __compressed_pair_elem {
44 using _ParamT = _Tp;
45 using reference = _Tp&;
46 using const_reference = const _Tp&;
47
48 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair_elem(__default_init_tag) {}
49 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair_elem(__value_init_tag) : __value_() {}
50
51 template <class _Up, __enable_if_t<!is_same<__compressed_pair_elem, __decay_t<_Up> >::value, int> = 0>
52 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair_elem(_Up&& __u)
53 : __value_(std::forward<_Up>(__u)) {}
54
55#ifndef _LIBCPP_CXX03_LANG
56 template <class... _Args, size_t... _Indices>
57 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 explicit __compressed_pair_elem(
58 piecewise_construct_t, tuple<_Args...> __args, __tuple_indices<_Indices...>)
59 : __value_(std::forward<_Args>(std::get<_Indices>(__args))...) {}
60#endif
61
62 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference __get() _NOEXCEPT { return __value_; }
63 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR const_reference __get() const _NOEXCEPT { return __value_; }
64
65private:
66 _Tp __value_;
67};
68
69template <class _Tp, int _Idx>
70struct __compressed_pair_elem<_Tp, _Idx, true> : private _Tp {
71 using _ParamT = _Tp;
72 using reference = _Tp&;
73 using const_reference = const _Tp&;
74 using __value_type = _Tp;
75
76 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair_elem() = default;
77 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair_elem(__default_init_tag) {}
78 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair_elem(__value_init_tag) : __value_type() {}
79
80 template <class _Up, __enable_if_t<!is_same<__compressed_pair_elem, __decay_t<_Up> >::value, int> = 0>
81 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair_elem(_Up&& __u)
82 : __value_type(std::forward<_Up>(__u)) {}
83
84#ifndef _LIBCPP_CXX03_LANG
85 template <class... _Args, size_t... _Indices>
86 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17
87 __compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args, __tuple_indices<_Indices...>)
88 : __value_type(std::forward<_Args>(std::get<_Indices>(__args))...) {}
89#endif
90
91 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference __get() _NOEXCEPT { return *this; }
92 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR const_reference __get() const _NOEXCEPT { return *this; }
93};
94
95template <class _T1, class _T2>
96class __compressed_pair : private __compressed_pair_elem<_T1, 0>, private __compressed_pair_elem<_T2, 1> {
97public:
98 // NOTE: This static assert should never fire because __compressed_pair
99 // is *almost never* used in a scenario where it's possible for T1 == T2.
100 // (The exception is std::function where it is possible that the function
101 // object and the allocator have the same type).
102 static_assert(
103 (!is_same<_T1, _T2>::value),
104 "__compressed_pair cannot be instantiated when T1 and T2 are the same type; "
105 "The current implementation is NOT ABI-compatible with the previous implementation for this configuration");
106
107 using _Base1 _LIBCPP_NODEBUG = __compressed_pair_elem<_T1, 0>;
108 using _Base2 _LIBCPP_NODEBUG = __compressed_pair_elem<_T2, 1>;
109
110 template <bool _Dummy = true,
111 __enable_if_t< __dependent_type<is_default_constructible<_T1>, _Dummy>::value &&
112 __dependent_type<is_default_constructible<_T2>, _Dummy>::value,
113 int> = 0>
114 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair()
115 : _Base1(__value_init_tag()), _Base2(__value_init_tag()) {}
116
117 template <class _U1, class _U2>
118 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __compressed_pair(_U1&& __t1, _U2&& __t2)
119 : _Base1(std::forward<_U1>(__t1)), _Base2(std::forward<_U2>(__t2)) {}
120
121#ifndef _LIBCPP_CXX03_LANG
122 template <class... _Args1, class... _Args2>
123 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 explicit __compressed_pair(
124 piecewise_construct_t __pc, tuple<_Args1...> __first_args, tuple<_Args2...> __second_args)
125 : _Base1(__pc, std::move(__first_args), typename __make_tuple_indices<sizeof...(_Args1)>::type()),
126 _Base2(__pc, std::move(__second_args), typename __make_tuple_indices<sizeof...(_Args2)>::type()) {}
127#endif
128
129 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename _Base1::reference first() _NOEXCEPT {
130 return static_cast<_Base1&>(*this).__get();
131 }
132
133 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR typename _Base1::const_reference first() const _NOEXCEPT {
134 return static_cast<_Base1 const&>(*this).__get();
135 }
136
137 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename _Base2::reference second() _NOEXCEPT {
138 return static_cast<_Base2&>(*this).__get();
139 }
140
141 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR typename _Base2::const_reference second() const _NOEXCEPT {
142 return static_cast<_Base2 const&>(*this).__get();
143 }
144
145 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR static _Base1* __get_first_base(__compressed_pair* __pair) _NOEXCEPT {
146 return static_cast<_Base1*>(__pair);
147 }
148 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR static _Base2* __get_second_base(__compressed_pair* __pair) _NOEXCEPT {
149 return static_cast<_Base2*>(__pair);
150 }
151
152 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void swap(__compressed_pair& __x)
153 _NOEXCEPT_(__is_nothrow_swappable_v<_T1>&& __is_nothrow_swappable_v<_T2>) {
154 using std::swap;
155 swap(first(), __x.first());
156 swap(second(), __x.second());
157 }
158};
159
160template <class _T1, class _T2>
161inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
162swap(__compressed_pair<_T1, _T2>& __x, __compressed_pair<_T1, _T2>& __y)
163 _NOEXCEPT_(__is_nothrow_swappable_v<_T1>&& __is_nothrow_swappable_v<_T2>) {
164 __x.swap(__y);
165}
166
167_LIBCPP_END_NAMESPACE_STD
168
169_LIBCPP_POP_MACROS
170
171#endif // _LIBCPP___MEMORY_COMPRESSED_PAIR_H
172