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invoke.h revision 1.1 
      1 // Implementation of INVOKE -*- C++ -*-
      2 
      3 // Copyright (C) 2016-2017 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
    105