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