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// Implementation of INVOKE -*- C++ -*-
// Copyright (C) 2016-2021 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/bits/invoke.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{functional}
*/
#ifndef _GLIBCXX_INVOKE_H
#define _GLIBCXX_INVOKE_H 1
#pragma GCC system_header
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <type_traits>
#include <bits/move.h> // forward
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup utilities
* @{
*/
// Used by __invoke_impl instead of std::forward<_Tp> so that a
// reference_wrapper is converted to an lvalue-reference.
template<typename _Tp, typename _Up = typename __inv_unwrap<_Tp>::type>
constexpr _Up&&
__invfwd(typename remove_reference<_Tp>::type& __t) noexcept
{ return static_cast<_Up&&>(__t); }
template<typename _Res, typename _Fn, typename... _Args>
constexpr _Res
__invoke_impl(__invoke_other, _Fn&& __f, _Args&&... __args)
{ return std::forward<_Fn>(__f)(std::forward<_Args>(__args)...); }
template<typename _Res, typename _MemFun, typename _Tp, typename... _Args>
constexpr _Res
__invoke_impl(__invoke_memfun_ref, _MemFun&& __f, _Tp&& __t,
_Args&&... __args)
{ return (__invfwd<_Tp>(__t).*__f)(std::forward<_Args>(__args)...); }
template<typename _Res, typename _MemFun, typename _Tp, typename... _Args>
constexpr _Res
__invoke_impl(__invoke_memfun_deref, _MemFun&& __f, _Tp&& __t,
_Args&&... __args)
{
return ((*std::forward<_Tp>(__t)).*__f)(std::forward<_Args>(__args)...);
}
template<typename _Res, typename _MemPtr, typename _Tp>
constexpr _Res
__invoke_impl(__invoke_memobj_ref, _MemPtr&& __f, _Tp&& __t)
{ return __invfwd<_Tp>(__t).*__f; }
template<typename _Res, typename _MemPtr, typename _Tp>
constexpr _Res
__invoke_impl(__invoke_memobj_deref, _MemPtr&& __f, _Tp&& __t)
{ return (*std::forward<_Tp>(__t)).*__f; }
/// Invoke a callable object.
template<typename _Callable, typename... _Args>
constexpr typename __invoke_result<_Callable, _Args...>::type
__invoke(_Callable&& __fn, _Args&&... __args)
noexcept(__is_nothrow_invocable<_Callable, _Args...>::value)
{
using __result = __invoke_result<_Callable, _Args...>;
using __type = typename __result::type;
using __tag = typename __result::__invoke_type;
return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
std::forward<_Args>(__args)...);
}
#if __cplusplus >= 201703L
// INVOKE<R>: Invoke a callable object and convert the result to R.
template<typename _Res, typename _Callable, typename... _Args>
constexpr enable_if_t<is_invocable_r_v<_Res, _Callable, _Args...>, _Res>
__invoke_r(_Callable&& __fn, _Args&&... __args)
noexcept(is_nothrow_invocable_r_v<_Res, _Callable, _Args...>)
{
using __result = __invoke_result<_Callable, _Args...>;
using __type = typename __result::type;
using __tag = typename __result::__invoke_type;
if constexpr (is_void_v<_Res>)
std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
std::forward<_Args>(__args)...);
else
return std::__invoke_impl<__type>(__tag{},
std::forward<_Callable>(__fn),
std::forward<_Args>(__args)...);
}
#else // C++11
template<typename _Res, typename _Callable, typename... _Args>
using __can_invoke_as_void = __enable_if_t<
__and_<is_void<_Res>, __is_invocable<_Callable, _Args...>>::value,
_Res
>;
template<typename _Res, typename _Callable, typename... _Args>
using __can_invoke_as_nonvoid = __enable_if_t<
__and_<__not_<is_void<_Res>>,
is_convertible<typename __invoke_result<_Callable, _Args...>::type,
_Res>
>::value,
_Res
>;
// INVOKE<R>: Invoke a callable object and convert the result to R.
template<typename _Res, typename _Callable, typename... _Args>
constexpr __can_invoke_as_nonvoid<_Res, _Callable, _Args...>
__invoke_r(_Callable&& __fn, _Args&&... __args)
{
using __result = __invoke_result<_Callable, _Args...>;
using __type = typename __result::type;
using __tag = typename __result::__invoke_type;
return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
std::forward<_Args>(__args)...);
}
// INVOKE<R> when R is cv void
template<typename _Res, typename _Callable, typename... _Args>
_GLIBCXX14_CONSTEXPR __can_invoke_as_void<_Res, _Callable, _Args...>
__invoke_r(_Callable&& __fn, _Args&&... __args)
{
using __result = __invoke_result<_Callable, _Args...>;
using __type = typename __result::type;
using __tag = typename __result::__invoke_type;
std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
std::forward<_Args>(__args)...);
}
#endif // C++11
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++11
#endif // _GLIBCXX_INVOKE_H
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