1// <utility> -*- C++ -*- 2 3// Copyright (C) 2001-2022 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 82namespace std _GLIBCXX_VISIBILITY(default) 83{ 84_GLIBCXX_BEGIN_NAMESPACE_VERSION 85 86#if __cplusplus >= 201402L 87#define __cpp_lib_exchange_function 201304L 88 89#if __cplusplus > 201703L 90# define __cpp_lib_constexpr_algorithms 201806L 91#endif 92 93 /// Assign @p __new_val to @p __obj and return its previous value. 94 template <typename _Tp, typename _Up = _Tp> 95 _GLIBCXX20_CONSTEXPR 96 inline _Tp 97 exchange(_Tp& __obj, _Up&& __new_val) 98 noexcept(__and_<is_nothrow_move_constructible<_Tp>, 99 is_nothrow_assignable<_Tp&, _Up>>::value) 100 { return std::__exchange(__obj, std::forward<_Up>(__new_val)); } 101 102#if __cplusplus >= 201703L 103 104#define __cpp_lib_as_const 201510L 105 template<typename _Tp> 106 [[nodiscard]] 107 constexpr add_const_t<_Tp>& 108 as_const(_Tp& __t) noexcept 109 { return __t; } 110 111 template<typename _Tp> 112 void as_const(const _Tp&&) = delete; 113 114#if __cplusplus > 201703L 115#define __cpp_lib_integer_comparison_functions 202002L 116 117 template<typename _Tp, typename _Up> 118 constexpr bool 119 cmp_equal(_Tp __t, _Up __u) noexcept 120 { 121 static_assert(__is_standard_integer<_Tp>::value); 122 static_assert(__is_standard_integer<_Up>::value); 123 124 if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>) 125 return __t == __u; 126 else if constexpr (is_signed_v<_Tp>) 127 return __t >= 0 && make_unsigned_t<_Tp>(__t) == __u; 128 else 129 return __u >= 0 && __t == make_unsigned_t<_Up>(__u); 130 } 131 132 template<typename _Tp, typename _Up> 133 constexpr bool 134 cmp_not_equal(_Tp __t, _Up __u) noexcept 135 { return !std::cmp_equal(__t, __u); } 136 137 template<typename _Tp, typename _Up> 138 constexpr bool 139 cmp_less(_Tp __t, _Up __u) noexcept 140 { 141 static_assert(__is_standard_integer<_Tp>::value); 142 static_assert(__is_standard_integer<_Up>::value); 143 144 if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>) 145 return __t < __u; 146 else if constexpr (is_signed_v<_Tp>) 147 return __t < 0 || make_unsigned_t<_Tp>(__t) < __u; 148 else 149 return __u >= 0 && __t < make_unsigned_t<_Up>(__u); 150 } 151 152 template<typename _Tp, typename _Up> 153 constexpr bool 154 cmp_greater(_Tp __t, _Up __u) noexcept 155 { return std::cmp_less(__u, __t); } 156 157 template<typename _Tp, typename _Up> 158 constexpr bool 159 cmp_less_equal(_Tp __t, _Up __u) noexcept 160 { return !std::cmp_less(__u, __t); } 161 162 template<typename _Tp, typename _Up> 163 constexpr bool 164 cmp_greater_equal(_Tp __t, _Up __u) noexcept 165 { return !std::cmp_less(__t, __u); } 166 167 template<typename _Res, typename _Tp> 168 constexpr bool 169 in_range(_Tp __t) noexcept 170 { 171 static_assert(__is_standard_integer<_Res>::value); 172 static_assert(__is_standard_integer<_Tp>::value); 173 using __gnu_cxx::__int_traits; 174 175 if constexpr (is_signed_v<_Tp> == is_signed_v<_Res>) 176 return __int_traits<_Res>::__min <= __t 177 && __t <= __int_traits<_Res>::__max; 178 else if constexpr (is_signed_v<_Tp>) 179 return __t >= 0 180 && make_unsigned_t<_Tp>(__t) <= __int_traits<_Res>::__max; 181 else 182 return __t <= make_unsigned_t<_Res>(__int_traits<_Res>::__max); 183 } 184 185#if __cplusplus > 202002L 186#define __cpp_lib_to_underlying 202102L 187 /// Convert an object of enumeration type to its underlying type. 188 template<typename _Tp> 189 [[nodiscard]] 190 constexpr underlying_type_t<_Tp> 191 to_underlying(_Tp __value) noexcept 192 { return static_cast<underlying_type_t<_Tp>>(__value); } 193 194#define __cpp_lib_unreachable 202202L 195 /// Informs the compiler that program control flow never reaches this point. 196 /** 197 * Evaluating a call to this function results in undefined behaviour. 198 * This can be used as an assertion informing the compiler that certain 199 * conditions are impossible, for when the compiler is unable to determine 200 * that by itself. 201 * 202 * For example, it can be used to prevent warnings about reaching the 203 * end of a non-void function without returning. 204 * 205 * @since C++23 206 */ 207 [[noreturn,__gnu__::__always_inline__]] 208 inline void 209 unreachable() 210 { 211#ifdef _GLIBCXX_DEBUG 212 std::__glibcxx_assert_fail(nullptr, 0, "std::unreachable()", nullptr); 213#elif defined _GLIBCXX_ASSERTIONS 214 __builtin_trap(); 215#else 216 __builtin_unreachable(); 217#endif 218 } 219#endif // C++23 220#endif // C++20 221#endif // C++17 222#endif // C++14 223 224_GLIBCXX_END_NAMESPACE_VERSION 225} // namespace 226 227#endif 228 229#endif /* _GLIBCXX_UTILITY */ 230