libstdc++-v3/include/bits/invoke.h

   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
  41 namespace 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