204 lines
5.7 KiB
C++
204 lines
5.7 KiB
C++
// Implementation of std::move_only_function -*- C++ -*-
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// Copyright The GNU Toolchain Authors.
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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/move_only_function.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_MOVE_ONLY_FUNCTION_H
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#define _GLIBCXX_MOVE_ONLY_FUNCTION_H 1
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#pragma GCC system_header
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#if __cplusplus > 202002L
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#include <bits/invoke.h>
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#include <bits/utility.h>
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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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#define __cpp_lib_move_only_function 202110L
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template<typename... _Signature>
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class move_only_function; // not defined
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/// @cond undocumented
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class _Mofunc_base
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{
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protected:
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_Mofunc_base() noexcept
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: _M_manage(_S_empty)
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{ }
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_Mofunc_base(_Mofunc_base&& __x) noexcept
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{
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_M_manage = std::__exchange(__x._M_manage, _S_empty);
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_M_manage(_M_storage, &__x._M_storage);
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}
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template<typename _Tp, typename... _Args>
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static constexpr bool
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_S_nothrow_init() noexcept
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{
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if constexpr (__stored_locally<_Tp>)
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return is_nothrow_constructible_v<_Tp, _Args...>;
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return false;
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}
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template<typename _Tp, typename... _Args>
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void
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_M_init(_Args&&... __args) noexcept(_S_nothrow_init<_Tp, _Args...>())
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{
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if constexpr (__stored_locally<_Tp>)
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::new (_M_storage._M_addr()) _Tp(std::forward<_Args>(__args)...);
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else
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_M_storage._M_p = new _Tp(std::forward<_Args>(__args)...);
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_M_manage = &_S_manage<_Tp>;
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}
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_Mofunc_base&
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operator=(_Mofunc_base&& __x) noexcept
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{
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_M_manage(_M_storage, nullptr);
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_M_manage = std::__exchange(__x._M_manage, _S_empty);
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_M_manage(_M_storage, &__x._M_storage);
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return *this;
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}
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_Mofunc_base&
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operator=(nullptr_t) noexcept
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{
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_M_manage(_M_storage, nullptr);
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_M_manage = _S_empty;
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return *this;
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}
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~_Mofunc_base() { _M_manage(_M_storage, nullptr); }
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void
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swap(_Mofunc_base& __x) noexcept
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{
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// Order of operations here is more efficient if __x is empty.
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_Storage __s;
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__x._M_manage(__s, &__x._M_storage);
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_M_manage(__x._M_storage, &_M_storage);
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__x._M_manage(_M_storage, &__s);
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std::swap(_M_manage, __x._M_manage);
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}
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template<typename _Tp, typename _Self>
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static _Tp*
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_S_access(_Self* __self) noexcept
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{
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if constexpr (__stored_locally<remove_const_t<_Tp>>)
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return static_cast<_Tp*>(__self->_M_storage._M_addr());
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else
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return static_cast<_Tp*>(__self->_M_storage._M_p);
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}
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private:
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struct _Storage
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{
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void* _M_addr() noexcept { return &_M_bytes[0]; }
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const void* _M_addr() const noexcept { return &_M_bytes[0]; }
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// We want to have enough space to store a simple delegate type.
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struct _Delegate { void (_Storage::*__pfm)(); _Storage* __obj; };
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union {
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void* _M_p;
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alignas(_Delegate) alignas(void(*)())
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unsigned char _M_bytes[sizeof(_Delegate)];
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};
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};
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template<typename _Tp>
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static constexpr bool __stored_locally
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= sizeof(_Tp) <= sizeof(_Storage) && alignof(_Tp) <= alignof(_Storage)
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&& is_nothrow_move_constructible_v<_Tp>;
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// A function that either destroys the target object stored in __target,
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// or moves the target object from *__src to __target.
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using _Manager = void (*)(_Storage& __target, _Storage* __src) noexcept;
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// The no-op manager function for objects with no target.
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static void _S_empty(_Storage&, _Storage*) noexcept { }
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// The real manager function for a target object of type _Tp.
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template<typename _Tp>
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static void
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_S_manage(_Storage& __target, _Storage* __src) noexcept
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{
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if constexpr (__stored_locally<_Tp>)
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{
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if (__src)
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{
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_Tp* __rval = static_cast<_Tp*>(__src->_M_addr());
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::new (__target._M_addr()) _Tp(std::move(*__rval));
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__rval->~_Tp();
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}
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else
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static_cast<_Tp*>(__target._M_addr())->~_Tp();
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}
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else
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{
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if (__src)
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__target._M_p = __src->_M_p;
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else
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delete static_cast<_Tp*>(__target._M_p);
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}
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}
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_Storage _M_storage;
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_Manager _M_manage;
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};
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template<typename _Tp>
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inline constexpr bool __is_move_only_function_v = false;
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template<typename _Tp>
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constexpr bool __is_move_only_function_v<move_only_function<_Tp>> = true;
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/// @endcond
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#include "mofunc_impl.h"
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#define _GLIBCXX_MOF_CV const
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#include "mofunc_impl.h"
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#define _GLIBCXX_MOF_REF &
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#include "mofunc_impl.h"
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#define _GLIBCXX_MOF_REF &&
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#include "mofunc_impl.h"
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#define _GLIBCXX_MOF_CV const
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#define _GLIBCXX_MOF_REF &
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#include "mofunc_impl.h"
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#define _GLIBCXX_MOF_CV const
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#define _GLIBCXX_MOF_REF &&
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#include "mofunc_impl.h"
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#endif // C++23
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#endif // _GLIBCXX_MOVE_ONLY_FUNCTION_H
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