1 // Concept-constrained comparison implementations -*- C++ -*- 2 3 // Copyright (C) 2019-2022 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 /** @file bits/ranges_cmp.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{functional} 28 */ 29 30 #ifndef _RANGES_CMP_H 31 #define _RANGES_CMP_H 1 32 33 #if __cplusplus > 201703L 34 # include <bits/move.h> 35 # include <concepts> 36 37 namespace std _GLIBCXX_VISIBILITY(default) 38 { 39 _GLIBCXX_BEGIN_NAMESPACE_VERSION 40 41 struct __is_transparent; // not defined 42 43 // Define std::identity here so that <iterator> and <ranges> 44 // don't need to include <bits/stl_function.h> to get it. 45 46 /// [func.identity] The identity function. 47 struct identity 48 { 49 template<typename _Tp> 50 [[nodiscard]] 51 constexpr _Tp&& 52 operator()(_Tp&& __t) const noexcept 53 { return std::forward<_Tp>(__t); } 54 55 using is_transparent = __is_transparent; 56 }; 57 58 #ifdef __cpp_lib_concepts 59 // Define this here, included by all the headers that need to define it. 60 #define __cpp_lib_ranges 202110L 61 62 namespace ranges 63 { 64 namespace __detail 65 { 66 // BUILTIN-PTR-CMP(T, <, U) 67 // This determines whether t < u results in a call to a built-in operator< 68 // comparing pointers. It doesn't work for function pointers (PR 93628). 69 template<typename _Tp, typename _Up> 70 concept __less_builtin_ptr_cmp 71 = requires (_Tp&& __t, _Up&& __u) { { __t < __u } -> same_as<bool>; } 72 && convertible_to<_Tp, const volatile void*> 73 && convertible_to<_Up, const volatile void*> 74 && (! requires(_Tp&& __t, _Up&& __u) 75 { operator<(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 76 && ! requires(_Tp&& __t, _Up&& __u) 77 { std::forward<_Tp>(__t).operator<(std::forward<_Up>(__u)); }); 78 } // namespace __detail 79 80 // [range.cmp] Concept-constrained comparisons 81 82 // _GLIBCXX_RESOLVE_LIB_DEFECTS 83 // 3530 BUILTIN-PTR-MEOW should not opt the type out of syntactic checks 84 85 /// ranges::equal_to function object type. 86 struct equal_to 87 { 88 template<typename _Tp, typename _Up> 89 requires equality_comparable_with<_Tp, _Up> 90 constexpr bool 91 operator()(_Tp&& __t, _Up&& __u) const 92 noexcept(noexcept(std::declval<_Tp>() == std::declval<_Up>())) 93 { return std::forward<_Tp>(__t) == std::forward<_Up>(__u); } 94 95 using is_transparent = __is_transparent; 96 }; 97 98 /// ranges::not_equal_to function object type. 99 struct not_equal_to 100 { 101 template<typename _Tp, typename _Up> 102 requires equality_comparable_with<_Tp, _Up> 103 constexpr bool 104 operator()(_Tp&& __t, _Up&& __u) const 105 noexcept(noexcept(std::declval<_Up>() == std::declval<_Tp>())) 106 { return !equal_to{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 107 108 using is_transparent = __is_transparent; 109 }; 110 111 /// ranges::less function object type. 112 struct less 113 { 114 template<typename _Tp, typename _Up> 115 requires totally_ordered_with<_Tp, _Up> 116 constexpr bool 117 operator()(_Tp&& __t, _Up&& __u) const 118 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>())) 119 { 120 if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>) 121 { 122 if (std::__is_constant_evaluated()) 123 return __t < __u; 124 125 auto __x = reinterpret_cast<__UINTPTR_TYPE__>( 126 static_cast<const volatile void*>(std::forward<_Tp>(__t))); 127 auto __y = reinterpret_cast<__UINTPTR_TYPE__>( 128 static_cast<const volatile void*>(std::forward<_Up>(__u))); 129 return __x < __y; 130 } 131 else 132 return std::forward<_Tp>(__t) < std::forward<_Up>(__u); 133 } 134 135 using is_transparent = __is_transparent; 136 }; 137 138 /// ranges::greater function object type. 139 struct greater 140 { 141 template<typename _Tp, typename _Up> 142 requires totally_ordered_with<_Tp, _Up> 143 constexpr bool 144 operator()(_Tp&& __t, _Up&& __u) const 145 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>())) 146 { return less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); } 147 148 using is_transparent = __is_transparent; 149 }; 150 151 /// ranges::greater_equal function object type. 152 struct greater_equal 153 { 154 template<typename _Tp, typename _Up> 155 requires totally_ordered_with<_Tp, _Up> 156 constexpr bool 157 operator()(_Tp&& __t, _Up&& __u) const 158 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>())) 159 { return !less{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 160 161 using is_transparent = __is_transparent; 162 }; 163 164 /// ranges::less_equal function object type. 165 struct less_equal 166 { 167 template<typename _Tp, typename _Up> 168 requires totally_ordered_with<_Tp, _Up> 169 constexpr bool 170 operator()(_Tp&& __t, _Up&& __u) const 171 noexcept(noexcept(std::declval<_Up>() < std::declval<_Tp>())) 172 { return !less{}(std::forward<_Up>(__u), std::forward<_Tp>(__t)); } 173 174 using is_transparent = __is_transparent; 175 }; 176 177 } // namespace ranges 178 #endif // library concepts 179 _GLIBCXX_END_NAMESPACE_VERSION 180 } // namespace std 181 #endif // C++20 182 #endif // _RANGES_CMP_H 183