1 // Concept-constrained comparison implementations -*- C++ -*- 2 3 // Copyright (C) 2019-2020 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/range_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 _RANGE_CMP_H 31 #define _RANGE_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 constexpr _Tp&& 51 operator()(_Tp&& __t) const noexcept 52 { return std::forward<_Tp>(__t); } 53 54 using is_transparent = __is_transparent; 55 }; 56 57 #ifdef __cpp_lib_concepts 58 // Define this here, included by all the headers that need to define it. 59 #define __cpp_lib_ranges 201911L 60 61 namespace ranges 62 { 63 namespace __detail 64 { 65 // BUILTIN-PTR-CMP(T, <, U) 66 // This determines whether t < u results in a call to a built-in operator< 67 // comparing pointers. It doesn't work for function pointers (PR 93628). 68 template<typename _Tp, typename _Up> 69 concept __less_builtin_ptr_cmp 70 = requires (_Tp&& __t, _Up&& __u) { { __t < __u } -> same_as<bool>; } 71 && convertible_to<_Tp, const volatile void*> 72 && convertible_to<_Up, const volatile void*> 73 && (! requires(_Tp&& __t, _Up&& __u) 74 { operator<(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 75 && ! requires(_Tp&& __t, _Up&& __u) 76 { std::forward<_Tp>(__t).operator<(std::forward<_Up>(__u)); }); 77 } // namespace __detail 78 79 // [range.cmp] Concept-constrained comparisons 80 81 // _GLIBCXX_RESOLVE_LIB_DEFECTS 82 // 3530 BUILTIN-PTR-MEOW should not opt the type out of syntactic checks 83 84 /// ranges::equal_to function object type. 85 struct equal_to 86 { 87 template<typename _Tp, typename _Up> 88 requires equality_comparable_with<_Tp, _Up> 89 constexpr bool 90 operator()(_Tp&& __t, _Up&& __u) const 91 noexcept(noexcept(std::declval<_Tp>() == std::declval<_Up>())) 92 { return std::forward<_Tp>(__t) == std::forward<_Up>(__u); } 93 94 using is_transparent = __is_transparent; 95 }; 96 97 /// ranges::not_equal_to function object type. 98 struct not_equal_to 99 { 100 template<typename _Tp, typename _Up> 101 requires equality_comparable_with<_Tp, _Up> 102 constexpr bool 103 operator()(_Tp&& __t, _Up&& __u) const 104 noexcept(noexcept(std::declval<_Up>() == std::declval<_Tp>())) 105 { return !equal_to{}(std::forward<_Tp>(__t), std::forward<_Up>(__u)); } 106 107 using is_transparent = __is_transparent; 108 }; 109 110 /// ranges::less function object type. 111 struct less 112 { 113 template<typename _Tp, typename _Up> 114 requires totally_ordered_with<_Tp, _Up> 115 constexpr bool 116 operator()(_Tp&& __t, _Up&& __u) const 117 noexcept(noexcept(std::declval<_Tp>() < std::declval<_Up>())) 118 { 119 if constexpr (__detail::__less_builtin_ptr_cmp<_Tp, _Up>) 120 { 121 #ifdef __cpp_lib_is_constant_evaluated 122 if (std::is_constant_evaluated()) 123 return __t < __u; 124 #endif 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 // _RANGE_CMP_H 183