invoke.h revision 1.1.1.2 
1// Implementation of INVOKE -*- C++ -*-
2
3// Copyright (C) 2016-2018 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