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The C and C++ Include Header Files
cat -n /usr/include/c++/15/utility
1 // <utility> -*- C++ -*- 2 3 // Copyright (C) 2001-2025 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 #ifdef _GLIBCXX_SYSHDR 59 #pragma GCC system_header 60 #endif 61 62 /** 63 * @defgroup utilities Utilities 64 * 65 * Basic function and class templates used with the rest of the library. 66 * Includes pair, swap, forward/move helpers, declval, integer_sequence. 67 */ 68 69 #include <bits/c++config.h> 70 #include <bits/stl_relops.h> 71 #include <bits/stl_pair.h> 72 73 #if __cplusplus >= 201103L 74 75 #include <initializer_list> 76 #include <type_traits> 77 #include <bits/move.h> 78 #include <bits/utility.h> 79 80 #if __cplusplus >= 202002L 81 #include <ext/numeric_traits.h> // __is_standard_integer, __int_traits 82 #endif 83 84 #if __cplusplus > 202302L 85 # include <bits/monostate.h> 86 #endif 87 88 #define __glibcxx_want_addressof_constexpr 89 #define __glibcxx_want_as_const 90 #define __glibcxx_want_constexpr_algorithms 91 #define __glibcxx_want_constexpr_utility 92 #define __glibcxx_want_exchange_function 93 #define __glibcxx_want_forward_like 94 #define __glibcxx_want_integer_comparison_functions 95 #define __glibcxx_want_integer_sequence 96 #define __glibcxx_want_ranges_zip 97 #define __glibcxx_want_to_underlying 98 #define __glibcxx_want_tuple_element_t 99 #define __glibcxx_want_tuples_by_type 100 #define __glibcxx_want_unreachable 101 #define __glibcxx_want_tuple_like 102 #define __glibcxx_want_constrained_equality 103 #include <bits/version.h> 104 105 namespace std _GLIBCXX_VISIBILITY(default) 106 { 107 _GLIBCXX_BEGIN_NAMESPACE_VERSION 108 109 #ifdef __cpp_lib_exchange_function // C++ >= 14 110 /// Assign @p __new_val to @p __obj and return its previous value. 111 template <typename _Tp, typename _Up = _Tp> 112 _GLIBCXX20_CONSTEXPR 113 inline _Tp 114 exchange(_Tp& __obj, _Up&& __new_val) 115 noexcept(__and_<is_nothrow_move_constructible<_Tp>, 116 is_nothrow_assignable<_Tp&, _Up>>::value) 117 { return std::__exchange(__obj, std::forward<_Up>(__new_val)); } 118 #endif 119 120 #ifdef __cpp_lib_as_const // C++ >= 17 121 template<typename _Tp> 122 [[nodiscard]] 123 constexpr add_const_t<_Tp>& 124 as_const(_Tp& __t) noexcept 125 { return __t; } 126 127 template<typename _Tp> 128 void as_const(const _Tp&&) = delete; 129 #endif 130 131 #ifdef __cpp_lib_integer_comparison_functions // C++ >= 20 132 template<typename _Tp, typename _Up> 133 constexpr bool 134 cmp_equal(_Tp __t, _Up __u) noexcept 135 { 136 static_assert(__is_standard_integer<_Tp>::value); 137 static_assert(__is_standard_integer<_Up>::value); 138 139 if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>) 140 return __t == __u; 141 else if constexpr (is_signed_v<_Tp>) 142 return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u; 143 else 144 return __u >= 0 && __t == make_unsigned_t<_Up>(__u); 145 } 146 147 template<typename _Tp, typename _Up> 148 constexpr bool 149 cmp_not_equal(_Tp __t, _Up __u) noexcept 150 { return !std::cmp_equal(__t, __u); } 151 152 template<typename _Tp, typename _Up> 153 constexpr bool 154 cmp_less(_Tp __t, _Up __u) noexcept 155 { 156 static_assert(__is_standard_integer<_Tp>::value); 157 static_assert(__is_standard_integer<_Up>::value); 158 159 if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>) 160 return __t < __u; 161 else if constexpr (is_signed_v<_Tp>) 162 return __t < 0 || make_unsigned_t<_Tp>(__t) < __u; 163 else 164 return __u >= 0 && __t < make_unsigned_t<_Up>(__u); 165 } 166 167 template<typename _Tp, typename _Up> 168 constexpr bool 169 cmp_greater(_Tp __t, _Up __u) noexcept 170 { return std::cmp_less(__u, __t); } 171 172 template<typename _Tp, typename _Up> 173 constexpr bool 174 cmp_less_equal(_Tp __t, _Up __u) noexcept 175 { return !std::cmp_less(__u, __t); } 176 177 template<typename _Tp, typename _Up> 178 constexpr bool 179 cmp_greater_equal(_Tp __t, _Up __u) noexcept 180 { return !std::cmp_less(__t, __u); } 181 182 template<typename _Res, typename _Tp> 183 constexpr bool 184 in_range(_Tp __t) noexcept 185 { 186 static_assert(__is_standard_integer<_Res>::value); 187 static_assert(__is_standard_integer<_Tp>::value); 188 using __gnu_cxx::__int_traits; 189 190 if constexpr (is_signed_v<_Tp> == is_signed_v<_Res>) 191 return __int_traits<_Res>::__min <= __t 192 && __t <= __int_traits<_Res>::__max; 193 else if constexpr (is_signed_v<_Tp>) 194 return __t >= 0 195 && make_unsigned_t<_Tp>(__t) <= __int_traits<_Res>::__max; 196 else 197 return __t <= make_unsigned_t<_Res>(__int_traits<_Res>::__max); 198 } 199 #endif // __cpp_lib_integer_comparison_functions 200 201 #ifdef __cpp_lib_to_underlying // C++ >= 23 202 /// Convert an object of enumeration type to its underlying type. 203 template<typename _Tp> 204 [[nodiscard]] 205 constexpr underlying_type_t<_Tp> 206 to_underlying(_Tp __value) noexcept 207 { return static_cast<underlying_type_t<_Tp>>(__value); } 208 #endif 209 210 #ifdef __cpp_lib_unreachable // C++ >= 23 211 /// Informs the compiler that program control flow never reaches this point. 212 /** 213 * Evaluating a call to this function results in undefined behaviour. 214 * This can be used as an assertion informing the compiler that certain 215 * conditions are impossible, for when the compiler is unable to determine 216 * that by itself. 217 * 218 * For example, it can be used to prevent warnings about reaching the 219 * end of a non-void function without returning. 220 * 221 * @since C++23 222 */ 223 [[noreturn,__gnu__::__always_inline__]] 224 inline void 225 unreachable() 226 { 227 #ifdef _GLIBCXX_DEBUG 228 std::__glibcxx_assert_fail(nullptr, 0, "std::unreachable()", nullptr); 229 #elif defined _GLIBCXX_ASSERTIONS 230 __builtin_trap(); 231 #else 232 __builtin_unreachable(); 233 #endif 234 } 235 #endif 236 237 _GLIBCXX_END_NAMESPACE_VERSION 238 } // namespace 239 240 #endif 241 242 #endif /* _GLIBCXX_UTILITY */
