165 lines
5.9 KiB
C++
165 lines
5.9 KiB
C++
// Implementation of INVOKE -*- C++ -*-
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// Copyright (C) 2016-2022 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file include/bits/invoke.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{functional}
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*/
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#ifndef _GLIBCXX_INVOKE_H
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#define _GLIBCXX_INVOKE_H 1
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#pragma GCC system_header
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#if __cplusplus < 201103L
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# include <bits/c++0x_warning.h>
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#else
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#include <type_traits>
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#include <bits/move.h> // forward
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @addtogroup utilities
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* @{
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*/
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// Used by __invoke_impl instead of std::forward<_Tp> so that a
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// reference_wrapper is converted to an lvalue-reference.
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template<typename _Tp, typename _Up = typename __inv_unwrap<_Tp>::type>
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constexpr _Up&&
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__invfwd(typename remove_reference<_Tp>::type& __t) noexcept
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{ return static_cast<_Up&&>(__t); }
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template<typename _Res, typename _Fn, typename... _Args>
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constexpr _Res
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__invoke_impl(__invoke_other, _Fn&& __f, _Args&&... __args)
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{ return std::forward<_Fn>(__f)(std::forward<_Args>(__args)...); }
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template<typename _Res, typename _MemFun, typename _Tp, typename... _Args>
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constexpr _Res
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__invoke_impl(__invoke_memfun_ref, _MemFun&& __f, _Tp&& __t,
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_Args&&... __args)
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{ return (__invfwd<_Tp>(__t).*__f)(std::forward<_Args>(__args)...); }
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template<typename _Res, typename _MemFun, typename _Tp, typename... _Args>
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constexpr _Res
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__invoke_impl(__invoke_memfun_deref, _MemFun&& __f, _Tp&& __t,
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_Args&&... __args)
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{
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return ((*std::forward<_Tp>(__t)).*__f)(std::forward<_Args>(__args)...);
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}
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template<typename _Res, typename _MemPtr, typename _Tp>
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constexpr _Res
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__invoke_impl(__invoke_memobj_ref, _MemPtr&& __f, _Tp&& __t)
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{ return __invfwd<_Tp>(__t).*__f; }
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template<typename _Res, typename _MemPtr, typename _Tp>
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constexpr _Res
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__invoke_impl(__invoke_memobj_deref, _MemPtr&& __f, _Tp&& __t)
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{ return (*std::forward<_Tp>(__t)).*__f; }
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/// Invoke a callable object.
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template<typename _Callable, typename... _Args>
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constexpr typename __invoke_result<_Callable, _Args...>::type
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__invoke(_Callable&& __fn, _Args&&... __args)
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noexcept(__is_nothrow_invocable<_Callable, _Args...>::value)
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{
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using __result = __invoke_result<_Callable, _Args...>;
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using __type = typename __result::type;
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using __tag = typename __result::__invoke_type;
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return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
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std::forward<_Args>(__args)...);
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}
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#if __cplusplus >= 201703L
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// INVOKE<R>: Invoke a callable object and convert the result to R.
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template<typename _Res, typename _Callable, typename... _Args>
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constexpr enable_if_t<is_invocable_r_v<_Res, _Callable, _Args...>, _Res>
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__invoke_r(_Callable&& __fn, _Args&&... __args)
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noexcept(is_nothrow_invocable_r_v<_Res, _Callable, _Args...>)
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{
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using __result = __invoke_result<_Callable, _Args...>;
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using __type = typename __result::type;
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using __tag = typename __result::__invoke_type;
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if constexpr (is_void_v<_Res>)
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std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
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std::forward<_Args>(__args)...);
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else
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return std::__invoke_impl<__type>(__tag{},
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std::forward<_Callable>(__fn),
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std::forward<_Args>(__args)...);
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}
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#else // C++11
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template<typename _Res, typename _Callable, typename... _Args>
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using __can_invoke_as_void = __enable_if_t<
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__and_<is_void<_Res>, __is_invocable<_Callable, _Args...>>::value,
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_Res
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>;
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template<typename _Res, typename _Callable, typename... _Args>
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using __can_invoke_as_nonvoid = __enable_if_t<
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__and_<__not_<is_void<_Res>>,
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is_convertible<typename __invoke_result<_Callable, _Args...>::type,
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_Res>
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>::value,
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_Res
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>;
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// INVOKE<R>: Invoke a callable object and convert the result to R.
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template<typename _Res, typename _Callable, typename... _Args>
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constexpr __can_invoke_as_nonvoid<_Res, _Callable, _Args...>
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__invoke_r(_Callable&& __fn, _Args&&... __args)
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{
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using __result = __invoke_result<_Callable, _Args...>;
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using __type = typename __result::type;
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using __tag = typename __result::__invoke_type;
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return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
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std::forward<_Args>(__args)...);
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}
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// INVOKE<R> when R is cv void
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template<typename _Res, typename _Callable, typename... _Args>
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_GLIBCXX14_CONSTEXPR __can_invoke_as_void<_Res, _Callable, _Args...>
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__invoke_r(_Callable&& __fn, _Args&&... __args)
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{
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using __result = __invoke_result<_Callable, _Args...>;
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using __type = typename __result::type;
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using __tag = typename __result::__invoke_type;
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std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
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std::forward<_Args>(__args)...);
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}
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#endif // C++11
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif // C++11
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#endif // _GLIBCXX_INVOKE_H
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