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1 : // Implementation of INVOKE -*- C++ -*-
2 :
3 : // Copyright (C) 2016-2021 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 186651104 : __invoke_impl(__invoke_other, _Fn&& __f, _Args&&... __args)
61 186651104 : { 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 91914801 : __invoke_impl(__invoke_memfun_deref, _MemFun&& __f, _Tp&& __t,
72 : _Args&&... __args)
73 : {
74 91914801 : 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 92856336 : __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 92856336 : return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
97 92856327 : 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 185709571 : __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 184127482 : std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
112 : std::forward<_Args>(__args)...);
113 : else
114 1576062 : return std::__invoke_impl<__type>(__tag{},
115 : std::forward<_Callable>(__fn),
116 1582090 : std::forward<_Args>(__args)...);
117 184127474 : }
118 : #else // C++11
119 : template<typename _Res, typename _Callable, typename... _Args>
120 : using __can_invoke_as_void = __enable_if_t<
121 : __and_<is_void<_Res>, __is_invocable<_Callable, _Args...>>::value,
122 : _Res
123 : >;
124 :
125 : template<typename _Res, typename _Callable, typename... _Args>
126 : using __can_invoke_as_nonvoid = __enable_if_t<
127 : __and_<__not_<is_void<_Res>>,
128 : is_convertible<typename __invoke_result<_Callable, _Args...>::type,
129 : _Res>
130 : >::value,
131 : _Res
132 : >;
133 :
134 : // INVOKE<R>: Invoke a callable object and convert the result to R.
135 : template<typename _Res, typename _Callable, typename... _Args>
136 : constexpr __can_invoke_as_nonvoid<_Res, _Callable, _Args...>
137 : __invoke_r(_Callable&& __fn, _Args&&... __args)
138 : {
139 : using __result = __invoke_result<_Callable, _Args...>;
140 : using __type = typename __result::type;
141 : using __tag = typename __result::__invoke_type;
142 : return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
143 : std::forward<_Args>(__args)...);
144 : }
145 :
146 : // INVOKE<R> when R is cv void
147 : template<typename _Res, typename _Callable, typename... _Args>
148 : _GLIBCXX14_CONSTEXPR __can_invoke_as_void<_Res, _Callable, _Args...>
149 : __invoke_r(_Callable&& __fn, _Args&&... __args)
150 : {
151 : using __result = __invoke_result<_Callable, _Args...>;
152 : using __type = typename __result::type;
153 : using __tag = typename __result::__invoke_type;
154 : std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
155 : std::forward<_Args>(__args)...);
156 : }
157 : #endif // C++11
158 :
159 : _GLIBCXX_END_NAMESPACE_VERSION
160 : } // namespace std
161 :
162 : #endif // C++11
163 :
164 : #endif // _GLIBCXX_INVOKE_H
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