713 lines
20 KiB
C++
713 lines
20 KiB
C++
// Implementation of std::function -*- C++ -*-
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// Copyright (C) 2004-2020 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/std_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_STD_FUNCTION_H
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#define _GLIBCXX_STD_FUNCTION_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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#if __cpp_rtti
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# include <typeinfo>
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#endif
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#include <bits/stl_function.h>
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#include <bits/invoke.h>
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#include <bits/refwrap.h>
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#include <bits/functexcept.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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/**
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* @brief Exception class thrown when class template function's
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* operator() is called with an empty target.
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* @ingroup exceptions
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*/
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class bad_function_call : public std::exception
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{
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public:
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virtual ~bad_function_call() noexcept;
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const char* what() const noexcept;
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};
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/**
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* Trait identifying "location-invariant" types, meaning that the
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* address of the object (or any of its members) will not escape.
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* Trivially copyable types are location-invariant and users can
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* specialize this trait for other types.
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*/
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template<typename _Tp>
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struct __is_location_invariant
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: is_trivially_copyable<_Tp>::type
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{ };
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class _Undefined_class;
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union _Nocopy_types
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{
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void* _M_object;
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const void* _M_const_object;
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void (*_M_function_pointer)();
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void (_Undefined_class::*_M_member_pointer)();
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};
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union [[gnu::may_alias]] _Any_data
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{
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void* _M_access() { return &_M_pod_data[0]; }
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const void* _M_access() const { return &_M_pod_data[0]; }
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template<typename _Tp>
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_Tp&
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_M_access()
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{ return *static_cast<_Tp*>(_M_access()); }
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template<typename _Tp>
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const _Tp&
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_M_access() const
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{ return *static_cast<const _Tp*>(_M_access()); }
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_Nocopy_types _M_unused;
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char _M_pod_data[sizeof(_Nocopy_types)];
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};
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enum _Manager_operation
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{
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__get_type_info,
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__get_functor_ptr,
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__clone_functor,
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__destroy_functor
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};
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template<typename _Signature>
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class function;
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/// Base class of all polymorphic function object wrappers.
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class _Function_base
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{
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public:
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static const size_t _M_max_size = sizeof(_Nocopy_types);
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static const size_t _M_max_align = __alignof__(_Nocopy_types);
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template<typename _Functor>
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class _Base_manager
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{
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protected:
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static const bool __stored_locally =
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(__is_location_invariant<_Functor>::value
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&& sizeof(_Functor) <= _M_max_size
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&& __alignof__(_Functor) <= _M_max_align
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&& (_M_max_align % __alignof__(_Functor) == 0));
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typedef integral_constant<bool, __stored_locally> _Local_storage;
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// Retrieve a pointer to the function object
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static _Functor*
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_M_get_pointer(const _Any_data& __source)
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{
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if _GLIBCXX17_CONSTEXPR (__stored_locally)
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{
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const _Functor& __f = __source._M_access<_Functor>();
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return const_cast<_Functor*>(std::__addressof(__f));
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}
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else // have stored a pointer
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return __source._M_access<_Functor*>();
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}
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// Clone a location-invariant function object that fits within
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// an _Any_data structure.
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static void
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_M_clone(_Any_data& __dest, const _Any_data& __source, true_type)
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{
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::new (__dest._M_access()) _Functor(__source._M_access<_Functor>());
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}
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// Clone a function object that is not location-invariant or
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// that cannot fit into an _Any_data structure.
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static void
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_M_clone(_Any_data& __dest, const _Any_data& __source, false_type)
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{
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__dest._M_access<_Functor*>() =
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new _Functor(*__source._M_access<const _Functor*>());
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}
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// Destroying a location-invariant object may still require
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// destruction.
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static void
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_M_destroy(_Any_data& __victim, true_type)
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{
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__victim._M_access<_Functor>().~_Functor();
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}
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// Destroying an object located on the heap.
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static void
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_M_destroy(_Any_data& __victim, false_type)
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{
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delete __victim._M_access<_Functor*>();
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}
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public:
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static bool
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_M_manager(_Any_data& __dest, const _Any_data& __source,
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_Manager_operation __op)
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{
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switch (__op)
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{
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#if __cpp_rtti
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case __get_type_info:
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__dest._M_access<const type_info*>() = &typeid(_Functor);
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break;
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#endif
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case __get_functor_ptr:
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__dest._M_access<_Functor*>() = _M_get_pointer(__source);
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break;
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case __clone_functor:
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_M_clone(__dest, __source, _Local_storage());
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break;
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case __destroy_functor:
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_M_destroy(__dest, _Local_storage());
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break;
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}
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return false;
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}
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static void
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_M_init_functor(_Any_data& __functor, _Functor&& __f)
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{ _M_init_functor(__functor, std::move(__f), _Local_storage()); }
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template<typename _Signature>
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static bool
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_M_not_empty_function(const function<_Signature>& __f)
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{ return static_cast<bool>(__f); }
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template<typename _Tp>
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static bool
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_M_not_empty_function(_Tp* __fp)
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{ return __fp != nullptr; }
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template<typename _Class, typename _Tp>
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static bool
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_M_not_empty_function(_Tp _Class::* __mp)
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{ return __mp != nullptr; }
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template<typename _Tp>
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static bool
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_M_not_empty_function(const _Tp&)
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{ return true; }
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private:
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static void
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_M_init_functor(_Any_data& __functor, _Functor&& __f, true_type)
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{ ::new (__functor._M_access()) _Functor(std::move(__f)); }
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static void
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_M_init_functor(_Any_data& __functor, _Functor&& __f, false_type)
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{ __functor._M_access<_Functor*>() = new _Functor(std::move(__f)); }
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};
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_Function_base() : _M_manager(nullptr) { }
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~_Function_base()
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{
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if (_M_manager)
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_M_manager(_M_functor, _M_functor, __destroy_functor);
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}
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bool _M_empty() const { return !_M_manager; }
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typedef bool (*_Manager_type)(_Any_data&, const _Any_data&,
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_Manager_operation);
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_Any_data _M_functor;
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_Manager_type _M_manager;
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};
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template<typename _Signature, typename _Functor>
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class _Function_handler;
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template<typename _Res, typename _Functor, typename... _ArgTypes>
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class _Function_handler<_Res(_ArgTypes...), _Functor>
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: public _Function_base::_Base_manager<_Functor>
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{
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typedef _Function_base::_Base_manager<_Functor> _Base;
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public:
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static bool
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_M_manager(_Any_data& __dest, const _Any_data& __source,
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_Manager_operation __op)
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{
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switch (__op)
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{
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#if __cpp_rtti
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case __get_type_info:
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__dest._M_access<const type_info*>() = &typeid(_Functor);
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break;
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#endif
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case __get_functor_ptr:
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__dest._M_access<_Functor*>() = _Base::_M_get_pointer(__source);
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break;
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default:
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_Base::_M_manager(__dest, __source, __op);
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}
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return false;
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}
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static _Res
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_M_invoke(const _Any_data& __functor, _ArgTypes&&... __args)
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{
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return std::__invoke_r<_Res>(*_Base::_M_get_pointer(__functor),
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std::forward<_ArgTypes>(__args)...);
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}
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};
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/**
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* @brief Primary class template for std::function.
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* @ingroup functors
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*
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* Polymorphic function wrapper.
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*/
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template<typename _Res, typename... _ArgTypes>
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class function<_Res(_ArgTypes...)>
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: public _Maybe_unary_or_binary_function<_Res, _ArgTypes...>,
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private _Function_base
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{
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template<typename _Func,
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typename _Res2 = __invoke_result<_Func&, _ArgTypes...>>
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struct _Callable
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: __is_invocable_impl<_Res2, _Res>::type
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{ };
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// Used so the return type convertibility checks aren't done when
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// performing overload resolution for copy construction/assignment.
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template<typename _Tp>
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struct _Callable<function, _Tp> : false_type { };
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template<typename _Cond, typename _Tp>
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using _Requires = typename enable_if<_Cond::value, _Tp>::type;
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public:
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typedef _Res result_type;
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// [3.7.2.1] construct/copy/destroy
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/**
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* @brief Default construct creates an empty function call wrapper.
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* @post @c !(bool)*this
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*/
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function() noexcept
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: _Function_base() { }
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/**
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* @brief Creates an empty function call wrapper.
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* @post @c !(bool)*this
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*/
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function(nullptr_t) noexcept
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: _Function_base() { }
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/**
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* @brief %Function copy constructor.
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* @param __x A %function object with identical call signature.
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* @post @c bool(*this) == bool(__x)
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*
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* The newly-created %function contains a copy of the target of @a
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* __x (if it has one).
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*/
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function(const function& __x)
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: _Function_base()
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{
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if (static_cast<bool>(__x))
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{
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__x._M_manager(_M_functor, __x._M_functor, __clone_functor);
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_M_invoker = __x._M_invoker;
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_M_manager = __x._M_manager;
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}
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}
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/**
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* @brief %Function move constructor.
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* @param __x A %function object rvalue with identical call signature.
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*
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* The newly-created %function contains the target of @a __x
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* (if it has one).
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*/
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function(function&& __x) noexcept
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: _Function_base()
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{ __x.swap(*this); }
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/**
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* @brief Builds a %function that targets a copy of the incoming
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* function object.
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* @param __f A %function object that is callable with parameters of
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* type @c T1, @c T2, ..., @c TN and returns a value convertible
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* to @c Res.
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*
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* The newly-created %function object will target a copy of
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* @a __f. If @a __f is @c reference_wrapper<F>, then this function
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* object will contain a reference to the function object @c
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* __f.get(). If @a __f is a NULL function pointer or NULL
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* pointer-to-member, the newly-created object will be empty.
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*
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* If @a __f is a non-NULL function pointer or an object of type @c
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* reference_wrapper<F>, this function will not throw.
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*/
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template<typename _Functor,
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typename = _Requires<__not_<is_same<_Functor, function>>, void>,
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typename = _Requires<_Callable<_Functor>, void>>
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function(_Functor __f)
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: _Function_base()
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{
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typedef _Function_handler<_Res(_ArgTypes...), _Functor> _My_handler;
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if (_My_handler::_M_not_empty_function(__f))
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{
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_My_handler::_M_init_functor(_M_functor, std::move(__f));
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_M_invoker = &_My_handler::_M_invoke;
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_M_manager = &_My_handler::_M_manager;
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}
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}
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/**
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* @brief %Function assignment operator.
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* @param __x A %function with identical call signature.
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* @post @c (bool)*this == (bool)x
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* @returns @c *this
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*
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* The target of @a __x is copied to @c *this. If @a __x has no
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* target, then @c *this will be empty.
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*
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* If @a __x targets a function pointer or a reference to a function
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* object, then this operation will not throw an %exception.
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*/
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function&
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operator=(const function& __x)
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{
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function(__x).swap(*this);
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return *this;
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}
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/**
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* @brief %Function move-assignment operator.
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* @param __x A %function rvalue with identical call signature.
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* @returns @c *this
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*
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* The target of @a __x is moved to @c *this. If @a __x has no
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* target, then @c *this will be empty.
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*
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* If @a __x targets a function pointer or a reference to a function
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* object, then this operation will not throw an %exception.
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*/
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function&
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operator=(function&& __x) noexcept
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{
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function(std::move(__x)).swap(*this);
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return *this;
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}
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/**
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* @brief %Function assignment to zero.
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* @post @c !(bool)*this
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* @returns @c *this
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*
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* The target of @c *this is deallocated, leaving it empty.
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*/
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function&
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operator=(nullptr_t) noexcept
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{
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if (_M_manager)
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{
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_M_manager(_M_functor, _M_functor, __destroy_functor);
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_M_manager = nullptr;
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_M_invoker = nullptr;
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}
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return *this;
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}
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/**
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* @brief %Function assignment to a new target.
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* @param __f A %function object that is callable with parameters of
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* type @c T1, @c T2, ..., @c TN and returns a value convertible
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* to @c Res.
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* @return @c *this
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*
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* This %function object wrapper will target a copy of @a
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* __f. If @a __f is @c reference_wrapper<F>, then this function
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* object will contain a reference to the function object @c
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* __f.get(). If @a __f is a NULL function pointer or NULL
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* pointer-to-member, @c this object will be empty.
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*
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* If @a __f is a non-NULL function pointer or an object of type @c
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* reference_wrapper<F>, this function will not throw.
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*/
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template<typename _Functor>
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_Requires<_Callable<typename decay<_Functor>::type>, function&>
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operator=(_Functor&& __f)
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{
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function(std::forward<_Functor>(__f)).swap(*this);
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return *this;
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}
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/// @overload
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template<typename _Functor>
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function&
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operator=(reference_wrapper<_Functor> __f) noexcept
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{
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function(__f).swap(*this);
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return *this;
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}
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// [3.7.2.2] function modifiers
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/**
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* @brief Swap the targets of two %function objects.
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* @param __x A %function with identical call signature.
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*
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* Swap the targets of @c this function object and @a __f. This
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* function will not throw an %exception.
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*/
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void swap(function& __x) noexcept
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{
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std::swap(_M_functor, __x._M_functor);
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std::swap(_M_manager, __x._M_manager);
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std::swap(_M_invoker, __x._M_invoker);
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}
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// [3.7.2.3] function capacity
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/**
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* @brief Determine if the %function wrapper has a target.
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*
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* @return @c true when this %function object contains a target,
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* or @c false when it is empty.
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*
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* This function will not throw an %exception.
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*/
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explicit operator bool() const noexcept
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{ return !_M_empty(); }
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// [3.7.2.4] function invocation
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/**
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* @brief Invokes the function targeted by @c *this.
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* @returns the result of the target.
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* @throws bad_function_call when @c !(bool)*this
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*
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* The function call operator invokes the target function object
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* stored by @c this.
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*/
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_Res
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operator()(_ArgTypes... __args) const
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{
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if (_M_empty())
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__throw_bad_function_call();
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return _M_invoker(_M_functor, std::forward<_ArgTypes>(__args)...);
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}
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#if __cpp_rtti
|
|
// [3.7.2.5] function target access
|
|
/**
|
|
* @brief Determine the type of the target of this function object
|
|
* wrapper.
|
|
*
|
|
* @returns the type identifier of the target function object, or
|
|
* @c typeid(void) if @c !(bool)*this.
|
|
*
|
|
* This function will not throw an %exception.
|
|
*/
|
|
const type_info&
|
|
target_type() const noexcept
|
|
{
|
|
if (_M_manager)
|
|
{
|
|
_Any_data __typeinfo_result;
|
|
_M_manager(__typeinfo_result, _M_functor, __get_type_info);
|
|
return *__typeinfo_result._M_access<const type_info*>();
|
|
}
|
|
else
|
|
return typeid(void);
|
|
}
|
|
|
|
/**
|
|
* @brief Access the stored target function object.
|
|
*
|
|
* @return Returns a pointer to the stored target function object,
|
|
* if @c typeid(_Functor).equals(target_type()); otherwise, a NULL
|
|
* pointer.
|
|
*
|
|
* This function does not throw exceptions.
|
|
*
|
|
* @{
|
|
*/
|
|
template<typename _Functor>
|
|
_Functor*
|
|
target() noexcept
|
|
{
|
|
const function* __const_this = this;
|
|
const _Functor* __func = __const_this->template target<_Functor>();
|
|
return const_cast<_Functor*>(__func);
|
|
}
|
|
|
|
template<typename _Functor>
|
|
const _Functor*
|
|
target() const noexcept
|
|
{
|
|
if (typeid(_Functor) == target_type() && _M_manager)
|
|
{
|
|
_Any_data __ptr;
|
|
_M_manager(__ptr, _M_functor, __get_functor_ptr);
|
|
return __ptr._M_access<const _Functor*>();
|
|
}
|
|
else
|
|
return nullptr;
|
|
}
|
|
// @}
|
|
#endif
|
|
|
|
private:
|
|
using _Invoker_type = _Res (*)(const _Any_data&, _ArgTypes&&...);
|
|
_Invoker_type _M_invoker;
|
|
};
|
|
|
|
#if __cpp_deduction_guides >= 201606
|
|
template<typename>
|
|
struct __function_guide_helper
|
|
{ };
|
|
|
|
template<typename _Res, typename _Tp, bool _Nx, typename... _Args>
|
|
struct __function_guide_helper<
|
|
_Res (_Tp::*) (_Args...) noexcept(_Nx)
|
|
>
|
|
{ using type = _Res(_Args...); };
|
|
|
|
template<typename _Res, typename _Tp, bool _Nx, typename... _Args>
|
|
struct __function_guide_helper<
|
|
_Res (_Tp::*) (_Args...) & noexcept(_Nx)
|
|
>
|
|
{ using type = _Res(_Args...); };
|
|
|
|
template<typename _Res, typename _Tp, bool _Nx, typename... _Args>
|
|
struct __function_guide_helper<
|
|
_Res (_Tp::*) (_Args...) const noexcept(_Nx)
|
|
>
|
|
{ using type = _Res(_Args...); };
|
|
|
|
template<typename _Res, typename _Tp, bool _Nx, typename... _Args>
|
|
struct __function_guide_helper<
|
|
_Res (_Tp::*) (_Args...) const & noexcept(_Nx)
|
|
>
|
|
{ using type = _Res(_Args...); };
|
|
|
|
template<typename _Res, typename... _ArgTypes>
|
|
function(_Res(*)(_ArgTypes...)) -> function<_Res(_ArgTypes...)>;
|
|
|
|
template<typename _Functor, typename _Signature = typename
|
|
__function_guide_helper<decltype(&_Functor::operator())>::type>
|
|
function(_Functor) -> function<_Signature>;
|
|
#endif
|
|
|
|
// [20.7.15.2.6] null pointer comparisons
|
|
|
|
/**
|
|
* @brief Compares a polymorphic function object wrapper against 0
|
|
* (the NULL pointer).
|
|
* @returns @c true if the wrapper has no target, @c false otherwise
|
|
*
|
|
* This function will not throw an %exception.
|
|
*/
|
|
template<typename _Res, typename... _Args>
|
|
inline bool
|
|
operator==(const function<_Res(_Args...)>& __f, nullptr_t) noexcept
|
|
{ return !static_cast<bool>(__f); }
|
|
|
|
#if __cpp_impl_three_way_comparison < 201907L
|
|
/// @overload
|
|
template<typename _Res, typename... _Args>
|
|
inline bool
|
|
operator==(nullptr_t, const function<_Res(_Args...)>& __f) noexcept
|
|
{ return !static_cast<bool>(__f); }
|
|
|
|
/**
|
|
* @brief Compares a polymorphic function object wrapper against 0
|
|
* (the NULL pointer).
|
|
* @returns @c false if the wrapper has no target, @c true otherwise
|
|
*
|
|
* This function will not throw an %exception.
|
|
*/
|
|
template<typename _Res, typename... _Args>
|
|
inline bool
|
|
operator!=(const function<_Res(_Args...)>& __f, nullptr_t) noexcept
|
|
{ return static_cast<bool>(__f); }
|
|
|
|
/// @overload
|
|
template<typename _Res, typename... _Args>
|
|
inline bool
|
|
operator!=(nullptr_t, const function<_Res(_Args...)>& __f) noexcept
|
|
{ return static_cast<bool>(__f); }
|
|
#endif
|
|
|
|
// [20.7.15.2.7] specialized algorithms
|
|
|
|
/**
|
|
* @brief Swap the targets of two polymorphic function object wrappers.
|
|
*
|
|
* This function will not throw an %exception.
|
|
*/
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2062. Effect contradictions w/o no-throw guarantee of std::function swaps
|
|
template<typename _Res, typename... _Args>
|
|
inline void
|
|
swap(function<_Res(_Args...)>& __x, function<_Res(_Args...)>& __y) noexcept
|
|
{ __x.swap(__y); }
|
|
|
|
#if __cplusplus >= 201703L
|
|
namespace __detail::__variant
|
|
{
|
|
template<typename> struct _Never_valueless_alt; // see <variant>
|
|
|
|
// Provide the strong exception-safety guarantee when emplacing a
|
|
// function into a variant.
|
|
template<typename _Signature>
|
|
struct _Never_valueless_alt<std::function<_Signature>>
|
|
: std::true_type
|
|
{ };
|
|
} // namespace __detail::__variant
|
|
#endif // C++17
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace std
|
|
|
|
#endif // C++11
|
|
#endif // _GLIBCXX_STD_FUNCTION_H
|