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1 | // <utility> -*- C++ -*- | |
2 | ||
3 | // Copyright (C) 2001-2024 Free Software Foundation, Inc. | |
4 | // | |
5 | // This file is part of the GNU ISO C++ Library. This library is free | |
6 | // software; you can redistribute it and/or modify it under the | |
7 | // terms of the GNU General Public License as published by the | |
8 | // Free Software Foundation; either version 3, or (at your option) | |
9 | // any later version. | |
10 | ||
11 | // This library is distributed in the hope that it will be useful, | |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | // GNU General Public License for more details. | |
15 | ||
16 | // Under Section 7 of GPL version 3, you are granted additional | |
17 | // permissions described in the GCC Runtime Library Exception, version | |
18 | // 3.1, as published by the Free Software Foundation. | |
19 | ||
20 | // You should have received a copy of the GNU General Public License and | |
21 | // a copy of the GCC Runtime Library Exception along with this program; | |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | // <http://www.gnu.org/licenses/>. | |
24 | ||
25 | /* | |
26 | * | |
27 | * Copyright (c) 1994 | |
28 | * Hewlett-Packard Company | |
29 | * | |
30 | * Permission to use, copy, modify, distribute and sell this software | |
31 | * and its documentation for any purpose is hereby granted without fee, | |
32 | * provided that the above copyright notice appear in all copies and | |
33 | * that both that copyright notice and this permission notice appear | |
34 | * in supporting documentation. Hewlett-Packard Company makes no | |
35 | * representations about the suitability of this software for any | |
36 | * purpose. It is provided "as is" without express or implied warranty. | |
37 | * | |
38 | * | |
39 | * Copyright (c) 1996,1997 | |
40 | * Silicon Graphics Computer Systems, Inc. | |
41 | * | |
42 | * Permission to use, copy, modify, distribute and sell this software | |
43 | * and its documentation for any purpose is hereby granted without fee, | |
44 | * provided that the above copyright notice appear in all copies and | |
45 | * that both that copyright notice and this permission notice appear | |
46 | * in supporting documentation. Silicon Graphics makes no | |
47 | * representations about the suitability of this software for any | |
48 | * purpose. It is provided "as is" without express or implied warranty. | |
49 | */ | |
50 | ||
51 | /** @file include/utility | |
52 | * This is a Standard C++ Library header. | |
53 | */ | |
54 | ||
55 | #ifndef _GLIBCXX_UTILITY | |
56 | #define _GLIBCXX_UTILITY 1 | |
57 | ||
58 | #pragma GCC system_header | |
59 | ||
60 | /** | |
61 | * @defgroup utilities Utilities | |
62 | * | |
63 | * Basic function and class templates used with the rest of the library. | |
64 | * Includes pair, swap, forward/move helpers, declval, integer_sequence. | |
65 | */ | |
66 | ||
67 | #include <bits/c++config.h> | |
68 | #include <bits/stl_relops.h> | |
69 | #include <bits/stl_pair.h> | |
70 | ||
71 | #if __cplusplus >= 201103L | |
72 | ||
73 | #include <initializer_list> | |
74 | #include <type_traits> | |
75 | #include <bits/move.h> | |
76 | #include <bits/utility.h> | |
77 | ||
78 | #if __cplusplus >= 202002L | |
79 | #include <ext/numeric_traits.h> // __is_standard_integer, __int_traits | |
80 | #endif | |
81 | ||
82 | #define __glibcxx_want_addressof_constexpr | |
83 | #define __glibcxx_want_as_const | |
84 | #define __glibcxx_want_constexpr_algorithms | |
85 | #define __glibcxx_want_constexpr_utility | |
86 | #define __glibcxx_want_exchange_function | |
87 | #define __glibcxx_want_forward_like | |
88 | #define __glibcxx_want_integer_comparison_functions | |
89 | #define __glibcxx_want_integer_sequence | |
90 | #define __glibcxx_want_ranges_zip | |
91 | #define __glibcxx_want_to_underlying | |
92 | #define __glibcxx_want_tuple_element_t | |
93 | #define __glibcxx_want_tuples_by_type | |
94 | #define __glibcxx_want_unreachable | |
95 | #include <bits/version.h> | |
96 | ||
97 | namespace std _GLIBCXX_VISIBILITY(default) | |
98 | { | |
99 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
100 | ||
101 | #ifdef __cpp_lib_exchange_function // C++ >= 14 | |
102 | /// Assign @p __new_val to @p __obj and return its previous value. | |
103 | template <typename _Tp, typename _Up = _Tp> | |
104 | _GLIBCXX20_CONSTEXPR | |
105 | inline _Tp | |
106 | exchange(_Tp& __obj, _Up&& __new_val) | |
107 | noexcept(__and_<is_nothrow_move_constructible<_Tp>, | |
108 | is_nothrow_assignable<_Tp&, _Up>>::value) | |
109 | { return std::__exchange(__obj, std::forward<_Up>(__new_val)); } | |
110 | #endif | |
111 | ||
112 | #ifdef __cpp_lib_as_const // C++ >= 17 | |
113 | template<typename _Tp> | |
114 | [[nodiscard]] | |
115 | constexpr add_const_t<_Tp>& | |
116 | as_const(_Tp& __t) noexcept | |
117 | { return __t; } | |
118 | ||
119 | template<typename _Tp> | |
120 | void as_const(const _Tp&&) = delete; | |
121 | #endif | |
122 | ||
123 | #ifdef __cpp_lib_integer_comparison_functions // C++ >= 20 | |
124 | template<typename _Tp, typename _Up> | |
125 | constexpr bool | |
126 | cmp_equal(_Tp __t, _Up __u) noexcept | |
127 | { | |
128 | static_assert(__is_standard_integer<_Tp>::value); | |
129 | static_assert(__is_standard_integer<_Up>::value); | |
130 | ||
131 | if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>) | |
132 | return __t == __u; | |
133 | else if constexpr (is_signed_v<_Tp>) | |
134 | return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u; | |
135 | else | |
136 | return __u >= 0 && __t == make_unsigned_t<_Up>(__u); | |
137 | } | |
138 | ||
139 | template<typename _Tp, typename _Up> | |
140 | constexpr bool | |
141 | cmp_not_equal(_Tp __t, _Up __u) noexcept | |
142 | { return !std::cmp_equal(__t, __u); } | |
143 | ||
144 | template<typename _Tp, typename _Up> | |
145 | constexpr bool | |
146 | cmp_less(_Tp __t, _Up __u) noexcept | |
147 | { | |
148 | static_assert(__is_standard_integer<_Tp>::value); | |
149 | static_assert(__is_standard_integer<_Up>::value); | |
150 | ||
151 | if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>) | |
152 | return __t < __u; | |
153 | else if constexpr (is_signed_v<_Tp>) | |
154 | return __t < 0 || make_unsigned_t<_Tp>(__t) < __u; | |
155 | else | |
156 | return __u >= 0 && __t < make_unsigned_t<_Up>(__u); | |
157 | } | |
158 | ||
159 | template<typename _Tp, typename _Up> | |
160 | constexpr bool | |
161 | cmp_greater(_Tp __t, _Up __u) noexcept | |
162 | { return std::cmp_less(__u, __t); } | |
163 | ||
164 | template<typename _Tp, typename _Up> | |
165 | constexpr bool | |
166 | cmp_less_equal(_Tp __t, _Up __u) noexcept | |
167 | { return !std::cmp_less(__u, __t); } | |
168 | ||
169 | template<typename _Tp, typename _Up> | |
170 | constexpr bool | |
171 | cmp_greater_equal(_Tp __t, _Up __u) noexcept | |
172 | { return !std::cmp_less(__t, __u); } | |
173 | ||
174 | template<typename _Res, typename _Tp> | |
175 | constexpr bool | |
176 | in_range(_Tp __t) noexcept | |
177 | { | |
178 | static_assert(__is_standard_integer<_Res>::value); | |
179 | static_assert(__is_standard_integer<_Tp>::value); | |
180 | using __gnu_cxx::__int_traits; | |
181 | ||
182 | if constexpr (is_signed_v<_Tp> == is_signed_v<_Res>) | |
183 | return __int_traits<_Res>::__min <= __t | |
184 | && __t <= __int_traits<_Res>::__max; | |
185 | else if constexpr (is_signed_v<_Tp>) | |
186 | return __t >= 0 | |
187 | && make_unsigned_t<_Tp>(__t) <= __int_traits<_Res>::__max; | |
188 | else | |
189 | return __t <= make_unsigned_t<_Res>(__int_traits<_Res>::__max); | |
190 | } | |
191 | #endif // __cpp_lib_integer_comparison_functions | |
192 | ||
193 | #ifdef __cpp_lib_to_underlying // C++ >= 23 | |
194 | /// Convert an object of enumeration type to its underlying type. | |
195 | template<typename _Tp> | |
196 | [[nodiscard]] | |
197 | constexpr underlying_type_t<_Tp> | |
198 | to_underlying(_Tp __value) noexcept | |
199 | { return static_cast<underlying_type_t<_Tp>>(__value); } | |
200 | #endif | |
201 | ||
202 | #ifdef __cpp_lib_unreachable // C++ >= 23 | |
203 | /// Informs the compiler that program control flow never reaches this point. | |
204 | /** | |
205 | * Evaluating a call to this function results in undefined behaviour. | |
206 | * This can be used as an assertion informing the compiler that certain | |
207 | * conditions are impossible, for when the compiler is unable to determine | |
208 | * that by itself. | |
209 | * | |
210 | * For example, it can be used to prevent warnings about reaching the | |
211 | * end of a non-void function without returning. | |
212 | * | |
213 | * @since C++23 | |
214 | */ | |
215 | [[noreturn,__gnu__::__always_inline__]] | |
216 | inline void | |
217 | unreachable() | |
218 | { | |
219 | #ifdef _GLIBCXX_DEBUG | |
220 | std::__glibcxx_assert_fail(nullptr, 0, "std::unreachable()", nullptr); | |
221 | #elif defined _GLIBCXX_ASSERTIONS | |
222 | __builtin_trap(); | |
223 | #else | |
224 | __builtin_unreachable(); | |
225 | #endif | |
226 | } | |
227 | #endif | |
228 | ||
229 | _GLIBCXX_END_NAMESPACE_VERSION | |
230 | } // namespace | |
231 | ||
232 | #endif | |
233 | ||
234 | #endif /* _GLIBCXX_UTILITY */ |