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