1// Implementation of INVOKE -*- C++ -*- 
2 
3// Copyright (C) 2016-2019 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 
41namespace std _GLIBCXX_VISIBILITY(default) 
42{ 
43_GLIBCXX_BEGIN_NAMESPACE_VERSION 
44 
45 /** 
46 * @addtogroup utilities 
47 * @{ 
48 */ 
49 
50 // Used by __invoke_impl instead of std::forward<_Tp> so that a 
51 // reference_wrapper is converted to an lvalue-reference. 
52 template<typename _Tp, typename _Up = typename __inv_unwrap<_Tp>::type> 
53 constexpr _Up&& 
54 __invfwd(typename remove_reference<_Tp>::type& __t) noexcept 
55 { return static_cast<_Up&&>(__t); } 
56 
57 template<typename _Res, typename _Fn, typename... _Args> 
58 constexpr _Res 
59 __invoke_impl(__invoke_other, _Fn&& __f, _Args&&... __args) 
60 { return std::forward<_Fn>(__f)(std::forward<_Args>(__args)...); } 
61 
62 template<typename _Res, typename _MemFun, typename _Tp, typename... _Args> 
63 constexpr _Res 
64 __invoke_impl(__invoke_memfun_ref, _MemFun&& __f, _Tp&& __t, 
65 _Args&&... __args) 
66 { return (__invfwd<_Tp>(__t).*__f)(std::forward<_Args>(__args)...); } 
67 
68 template<typename _Res, typename _MemFun, typename _Tp, typename... _Args> 
69 constexpr _Res 
70 __invoke_impl(__invoke_memfun_deref, _MemFun&& __f, _Tp&& __t, 
71 _Args&&... __args) 
72 { 
73 return ((*std::forward<_Tp>(__t)).*__f)(std::forward<_Args>(__args)...); 
74 } 
75 
76 template<typename _Res, typename _MemPtr, typename _Tp> 
77 constexpr _Res 
78 __invoke_impl(__invoke_memobj_ref, _MemPtr&& __f, _Tp&& __t) 
79 { return __invfwd<_Tp>(__t).*__f; } 
80 
81 template<typename _Res, typename _MemPtr, typename _Tp> 
82 constexpr _Res 
83 __invoke_impl(__invoke_memobj_deref, _MemPtr&& __f, _Tp&& __t) 
84 { return (*std::forward<_Tp>(__t)).*__f; } 
85 
86 /// Invoke a callable object. 
87 template<typename _Callable, typename... _Args> 
88 constexpr typename __invoke_result<_Callable, _Args...>::type 
89 __invoke(_Callable&& __fn, _Args&&... __args) 
90 noexcept(__is_nothrow_invocable<_Callable, _Args...>::value) 
91 { 
92 using __result = __invoke_result<_Callable, _Args...>; 
93 using __type = typename __result::type; 
94 using __tag = typename __result::__invoke_type; 
95 return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn), 
96 std::forward<_Args>(__args)...); 
97 } 
98 
99_GLIBCXX_END_NAMESPACE_VERSION 
100} // namespace std 
101 
102#endif // C++11 
103 
104#endif // _GLIBCXX_INVOKE_H 
105