1 // Implementation of INVOKE -*- C++ -*- 2 3 // Copyright (C) 2016-2024 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 include/bits/invoke.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 _GLIBCXX_INVOKE_H 31 #define _GLIBCXX_INVOKE_H 1 32 33 #pragma GCC system_header 34 35 #if __cplusplus < 201103L 36 # include <bits/c++0x_warning.h> 37 #else 38 39 #include <type_traits> 40 #include <bits/move.h> // forward 41 42 namespace std _GLIBCXX_VISIBILITY(default) 43 { 44 _GLIBCXX_BEGIN_NAMESPACE_VERSION 45 46 /** 47 * @addtogroup utilities 48 * @{ 49 */ 50 51 // Used by __invoke_impl instead of std::forward<_Tp> so that a 52 // reference_wrapper is converted to an lvalue-reference. 53 template<typename _Tp, typename _Up = typename __inv_unwrap<_Tp>::type> 54 constexpr _Up&& 55 __invfwd(typename remove_reference<_Tp>::type& __t) noexcept 56 { return static_cast<_Up&&>(__t); } 57 58 template<typename _Res, typename _Fn, typename... _Args> 59 constexpr _Res 60 __invoke_impl(__invoke_other, _Fn&& __f, _Args&&... __args) 61 { return std::forward<_Fn>(__f)(std::forward<_Args>(__args)...); } 62 63 template<typename _Res, typename _MemFun, typename _Tp, typename... _Args> 64 constexpr _Res 65 __invoke_impl(__invoke_memfun_ref, _MemFun&& __f, _Tp&& __t, 66 _Args&&... __args) 67 { return (__invfwd<_Tp>(__t).*__f)(std::forward<_Args>(__args)...); } 68 69 template<typename _Res, typename _MemFun, typename _Tp, typename... _Args> 70 constexpr _Res 71 __invoke_impl(__invoke_memfun_deref, _MemFun&& __f, _Tp&& __t, 72 _Args&&... __args) 73 { 74 return ((*std::forward<_Tp>(__t)).*__f)(std::forward<_Args>(__args)...); 75 } 76 77 template<typename _Res, typename _MemPtr, typename _Tp> 78 constexpr _Res 79 __invoke_impl(__invoke_memobj_ref, _MemPtr&& __f, _Tp&& __t) 80 { return __invfwd<_Tp>(__t).*__f; } 81 82 template<typename _Res, typename _MemPtr, typename _Tp> 83 constexpr _Res 84 __invoke_impl(__invoke_memobj_deref, _MemPtr&& __f, _Tp&& __t) 85 { return (*std::forward<_Tp>(__t)).*__f; } 86 87 /// Invoke a callable object. 88 template<typename _Callable, typename... _Args> 89 constexpr typename __invoke_result<_Callable, _Args...>::type 90 __invoke(_Callable&& __fn, _Args&&... __args) 91 noexcept(__is_nothrow_invocable<_Callable, _Args...>::value) 92 { 93 using __result = __invoke_result<_Callable, _Args...>; 94 using __type = typename __result::type; 95 using __tag = typename __result::__invoke_type; 96 return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn), 97 std::forward<_Args>(__args)...); 98 } 99 100 #if __cplusplus >= 201703L 101 // INVOKE<R>: Invoke a callable object and convert the result to R. 102 template<typename _Res, typename _Callable, typename... _Args> 103 constexpr enable_if_t<is_invocable_r_v<_Res, _Callable, _Args...>, _Res> 104 __invoke_r(_Callable&& __fn, _Args&&... __args) 105 noexcept(is_nothrow_invocable_r_v<_Res, _Callable, _Args...>) 106 { 107 using __result = __invoke_result<_Callable, _Args...>; 108 using __type = typename __result::type; 109 using __tag = typename __result::__invoke_type; 110 if constexpr (is_void_v<_Res>) 111 std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn), 112 std::forward<_Args>(__args)...); 113 else 114 return std::__invoke_impl<__type>(__tag{}, 115 std::forward<_Callable>(__fn), 116 std::forward<_Args>(__args)...); 117 } 118 #else // C++11 or C++14 119 // This is a non-SFINAE-friendly std::invoke_r<R>(fn, args...) for C++11/14. 120 // It's used in std::function, std::bind, and std::packaged_task. Only 121 // std::function is constrained on is_invocable_r, but that is checked on 122 // construction so doesn't need to be checked again when calling __invoke_r. 123 // Consequently, these __invoke_r overloads do not check for invocable 124 // arguments, nor check that the invoke result is convertible to R. 125 126 // INVOKE<R>: Invoke a callable object and convert the result to R. 127 template<typename _Res, typename _Callable, typename... _Args> 128 constexpr __enable_if_t<!is_void<_Res>::value, _Res> 129 __invoke_r(_Callable&& __fn, _Args&&... __args) 130 { 131 using __result = __invoke_result<_Callable, _Args...>; 132 using __type = typename __result::type; 133 #if __has_builtin(__reference_converts_from_temporary) 134 static_assert(!__reference_converts_from_temporary(_Res, __type), 135 "INVOKE<R> must not create a dangling reference"); 136 #endif 137 using __tag = typename __result::__invoke_type; 138 return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn), 139 std::forward<_Args>(__args)...); 140 } 141 142 // INVOKE<R> when R is cv void 143 template<typename _Res, typename _Callable, typename... _Args> 144 _GLIBCXX14_CONSTEXPR __enable_if_t<is_void<_Res>::value, _Res> 145 __invoke_r(_Callable&& __fn, _Args&&... __args) 146 { 147 using __result = __invoke_result<_Callable, _Args...>; 148 using __type = typename __result::type; 149 using __tag = typename __result::__invoke_type; 150 std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn), 151 std::forward<_Args>(__args)...); 152 } 153 #endif // C++11 or C++14 154 155 _GLIBCXX_END_NAMESPACE_VERSION 156 } // namespace std 157 158 #endif // C++11 159 160 #endif // _GLIBCXX_INVOKE_H 161
Indexes created Sat Feb 28 05:31:39 UTC 2026