// -*- C++ -*- // Copyright (C) 2014 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 // . /** @file experimental/any * This is a TS C++ Library header. */ #ifndef _GLIBCXX_EXPERIMENTAL_ANY #define _GLIBCXX_EXPERIMENTAL_ANY 1 #pragma GCC system_header #if __cplusplus <= 201103L # include #else #include #include #include #include #include #include namespace std _GLIBCXX_VISIBILITY(default) { namespace experimental { inline namespace fundamentals_v1 { _GLIBCXX_BEGIN_NAMESPACE_VERSION /** * @defgroup any Type-safe container of any type * @ingroup experimental * * A type-safe container for single values of value types, as * described in n3804 "Any Library Proposal (Revision 3)". * * @{ */ #define __cpp_lib_experimental_any 201402 /** * @brief Exception class thrown by a failed @c any_cast * @ingroup exceptions */ class bad_any_cast : public bad_cast { public: virtual const char* what() const noexcept { return "bad any_cast"; } }; [[gnu::noreturn]] inline void __throw_bad_any_cast() { #ifdef __EXCEPTIONS throw bad_any_cast{}; #else __builtin_abort(); #endif } /** * @brief A type-safe container of any type. * * An @c any object's state is either empty or it stores a contained object * of CopyConstructible type. */ class any { // Holds either pointer to a heap object or the contained object itself. union _Storage { void* _M_ptr; std::aligned_storage::type _M_buffer; }; template, bool _Fits = (sizeof(_Tp) <= sizeof(_Storage))> using _Internal = std::integral_constant; template struct _Manager_internal; // uses small-object optimization template struct _Manager_external; // creates contained object on the heap template using _Manager = conditional_t<_Internal<_Tp>::value, _Manager_internal<_Tp>, _Manager_external<_Tp>>; #ifdef __GXX_RTTI // When RTTI is disabled __any_caster assumes the manager is either // _Manager_internal or _Manager_external, so this type must not be used. template struct _Manager_alloc; // creates contained object using an allocator template> using _ManagerAlloc = conditional_t<_Internal<_Tp>::value, _Manager_internal<_Tp>, _Manager_alloc<_Tp, _TpAlloc>>; #endif template> using _Decay = enable_if_t::value, _Decayed>; public: // construct/destruct /// Default constructor, creates an empty object. any() noexcept : _M_manager(nullptr) { } /// Copy constructor, copies the state of @p __other any(const any& __other) : _M_manager(__other._M_manager) { if (!__other.empty()) { _Arg __arg; __arg._M_any = this; _M_manager(_Op_clone, &__other, &__arg); } } /** * @brief Move constructor, transfer the state from @p __other * * @post @c __other.empty() (not guaranteed for other implementations) */ any(any&& __other) noexcept : _M_manager(__other._M_manager), _M_storage(__other._M_storage) { __other._M_manager = nullptr; } /// Construct with a copy of @p __value as the contained object. template , typename _Mgr = _Manager<_Tp>> any(_ValueType&& __value) : _M_manager(&_Mgr::_S_manage), _M_storage(_Mgr::_S_create(std::forward<_ValueType>(__value))) { static_assert(is_copy_constructible<_Tp>::value, "The contained object must be CopyConstructible"); } /// Allocator-extended default constructor (the allocator is ignored). template any(allocator_arg_t, const _Allocator&) noexcept : any() { } #ifdef __GXX_RTTI /// Construct with a copy of @p __value as the contained object. template , typename _Mgr = _ManagerAlloc<_Tp, _Allocator>> any(allocator_arg_t, const _Allocator& __a, _ValueType&& __value) : _M_manager(&_Mgr::_S_manage), _M_storage(_Mgr::_S_alloc(__a, std::forward<_ValueType>(__value))) { static_assert(is_copy_constructible<_Tp>::value, "The contained object must be CopyConstructible"); } #endif /* TODO: implement this somehow /// Allocator-extended copy constructor. template any(allocator_arg_t, const _Allocator& __a, const any& __other); */ /// Allocator-extended move constructor (the allocator is ignored). template any(allocator_arg_t, const _Allocator&, any&& __other) noexcept : any(std::move(__other)) { } /// Destructor, calls @c clear() ~any() { clear(); } // assignments /// Copy the state of any& operator=(const any& __rhs) { any(__rhs).swap(*this); return *this; } /** * @brief Move assignment operator * * @post @c __rhs.empty() (not guaranteed for other implementations) */ any& operator=(any&& __rhs) noexcept { any(std::move(__rhs)).swap(*this); return *this; } /// Store a copy of @p __rhs as the contained object. template any& operator=(_ValueType&& __rhs) { any(std::forward<_ValueType>(__rhs)).swap(*this); return *this; } // modifiers /// If not empty, destroy the contained object. void clear() noexcept { if (!empty()) { _M_manager(_Op_destroy, this, nullptr); _M_manager = nullptr; } } /// Exchange state with another object. void swap(any& __rhs) noexcept { std::swap(_M_manager, __rhs._M_manager); std::swap(_M_storage, __rhs._M_storage); } // observers /// Reports whether there is a contained object or not. bool empty() const noexcept { return _M_manager == nullptr; } #ifdef __GXX_RTTI /// The @c typeid of the contained object, or @c typeid(void) if empty. const type_info& type() const noexcept { if (empty()) return typeid(void); _Arg __arg; _M_manager(_Op_get_type_info, this, &__arg); return *__arg._M_typeinfo; } #endif template static constexpr bool __is_valid_cast() { return __or_, is_copy_constructible<_Tp>>::value; } private: enum _Op { _Op_access, _Op_get_type_info, _Op_clone, _Op_destroy }; union _Arg { void* _M_obj; const std::type_info* _M_typeinfo; any* _M_any; }; void (*_M_manager)(_Op, const any*, _Arg*); _Storage _M_storage; template friend void* __any_caster(const any* __any) { #ifdef __GXX_RTTI if (__any->type() != typeid(_Tp)) return nullptr; #else if (__any->_M_manager != &_Manager>::_S_manage) return nullptr; #endif _Arg __arg; __any->_M_manager(_Op_access, __any, &__arg); return __arg._M_obj; } // Manage in-place contained object. template struct _Manager_internal { static void _S_manage(_Op __which, const any* __anyp, _Arg* __arg); template static _Storage _S_create(_Up&& __value) { _Storage __storage; void* __addr = &__storage._M_buffer; ::new (__addr) _Tp(std::forward<_Up>(__value)); return __storage; } template static _Storage _S_alloc(const _Alloc&, _Up&& __value) { return _S_create(std::forward<_Up>(__value)); } }; // Manage external contained object. template struct _Manager_external { static void _S_manage(_Op __which, const any* __anyp, _Arg* __arg); template static _Storage _S_create(_Up&& __value) { _Storage __storage; __storage._M_ptr = new _Tp(std::forward<_Up>(__value)); return __storage; } }; #ifdef __GXX_RTTI // Manage external contained object using an allocator template struct _Manager_alloc { static_assert(std::is_same<_Tp, typename _Alloc::value_type>::value, "Allocator's value_type is correct"); // Type that holds contained object and allocator struct _Data; using _Traits = typename std::allocator_traits<_Alloc>::template rebind_traits<_Data>; static void _S_manage(_Op __which, const any* __anyp, _Arg* __arg); template static _Storage _S_alloc(const _Alloc& __a, _Up&& __value); }; #endif }; /// Exchange the states of two @c any objects. inline void swap(any& __x, any& __y) noexcept { __x.swap(__y); } /** * @brief Access the contained object. * * @tparam _ValueType A const-reference or CopyConstructible type. * @param __any The object to access. * @return The contained object. * @throw bad_any_cast If * __any.type() != typeid(remove_reference_t<_ValueType>) * */ template inline _ValueType any_cast(const any& __any) { static_assert(any::__is_valid_cast<_ValueType>(), "Template argument must be a reference or CopyConstructible type"); auto __p = any_cast>>(&__any); if (__p) return *__p; __throw_bad_any_cast(); } /** * @brief Access the contained object. * * @tparam _ValueType A reference or CopyConstructible type. * @param __any The object to access. * @return The contained object. * @throw bad_any_cast If * __any.type() != typeid(remove_reference_t<_ValueType>) * * * @{ */ template inline _ValueType any_cast(any& __any) { static_assert(any::__is_valid_cast<_ValueType>(), "Template argument must be a reference or CopyConstructible type"); auto __p = any_cast>(&__any); if (__p) return *__p; __throw_bad_any_cast(); } template inline _ValueType any_cast(any&& __any) { static_assert(any::__is_valid_cast<_ValueType>(), "Template argument must be a reference or CopyConstructible type"); auto __p = any_cast>(&__any); if (__p) return *__p; __throw_bad_any_cast(); } // @} /** * @brief Access the contained object. * * @tparam _ValueType The type of the contained object. * @param __any A pointer to the object to access. * @return The address of the contained object if * __any != nullptr && __any.type() == typeid(_ValueType) * , otherwise a null pointer. * * @{ */ template inline const _ValueType* any_cast(const any* __any) noexcept { if (__any) return static_cast<_ValueType*>(__any_caster<_ValueType>(__any)); return nullptr; } template inline _ValueType* any_cast(any* __any) noexcept { if (__any) return static_cast<_ValueType*>(__any_caster<_ValueType>(__any)); return nullptr; } // @} #ifdef __GXX_RTTI template struct any::_Manager_alloc<_Tp, _Alloc>::_Data { using _Traits = std::allocator_traits<_Alloc>; std::tuple<__gnu_cxx::__aligned_buffer<_Tp>, _Alloc> _M_data; _Alloc& _M_alloc() { return std::get<1>(_M_data); } const _Alloc& _M_alloc() const { return std::get<1>(_M_data); } _Tp* _M_obj() { return std::get<0>(_M_data)._M_ptr(); } const _Tp* _M_obj() const { return std::get<0>(_M_data)._M_ptr(); } template _Data(const _Alloc& __a, _Up&& __val) : _M_data(nullptr, __a) { this->_M_construct(std::__use_alloc<_Tp, _Alloc, _Up&&>(_M_alloc()), std::forward<_Up>(__val)); } ~_Data() { _Traits::destroy(_M_alloc(), _M_obj()); } template void _M_construct(__uses_alloc0, _Up&& __val) { _Traits::construct(_M_alloc(), _M_obj(), std::forward<_Up>(__val)); } template void _M_construct(__uses_alloc1<_Alloc> __a, _Up&& __val) { _Traits::construct(_M_alloc(), _M_obj(), std::allocator_arg, *__a._M_a, std::forward<_Up>(__val)); } template void _M_construct(__uses_alloc2<_Alloc> __a, _Up&& __val) { _Traits::construct(_M_alloc(), _M_obj(), std::forward<_Up>(__val), *__a._M_a); } }; template template any::_Storage any::_Manager_alloc<_Tp, _Alloc>:: _S_alloc(const _Alloc& __a, _Up&& __value) { typename _Traits::allocator_type __a2(__a); auto __guard = std::__allocate_guarded(__a2); any::_Storage __storage; __storage._M_ptr = __guard.get(); ::new(__storage._M_ptr) _Data{__a, std::forward<_Up>(__value)}; __guard = nullptr; return __storage; } #endif template void any::_Manager_internal<_Tp>:: _S_manage(_Op __which, const any* __any, _Arg* __arg) { // The contained object is in _M_storage._M_buffer auto __ptr = reinterpret_cast(&__any->_M_storage._M_buffer); switch (__which) { case _Op_access: __arg->_M_obj = const_cast<_Tp*>(__ptr); break; case _Op_get_type_info: #ifdef __GXX_RTTI __arg->_M_typeinfo = &typeid(_Tp); #endif break; case _Op_clone: ::new(&__arg->_M_any->_M_storage._M_buffer) _Tp(*__ptr); break; case _Op_destroy: __ptr->~_Tp(); break; } } template void any::_Manager_external<_Tp>:: _S_manage(_Op __which, const any* __any, _Arg* __arg) { // The contained object is *_M_storage._M_ptr auto __ptr = static_cast(__any->_M_storage._M_ptr); switch (__which) { case _Op_access: __arg->_M_obj = const_cast<_Tp*>(__ptr); break; case _Op_get_type_info: #ifdef __GXX_RTTI __arg->_M_typeinfo = &typeid(_Tp); #endif break; case _Op_clone: __arg->_M_any->_M_storage._M_ptr = new _Tp(*__ptr); break; case _Op_destroy: delete __ptr; break; } } #ifdef __GXX_RTTI template void any::_Manager_alloc<_Tp, _Alloc>:: _S_manage(_Op __which, const any* __any, _Arg* __arg) { // The contained object is at _M_storage._M_ptr->_M_obj() auto __ptr = static_cast(__any->_M_storage._M_ptr); switch (__which) { case _Op_access: __arg->_M_obj = const_cast<_Tp*>(__ptr->_M_obj()); break; case _Op_get_type_info: __arg->_M_typeinfo = &typeid(_Tp); break; case _Op_clone: __arg->_M_any->_M_storage = _S_alloc(__ptr->_M_alloc(), *__ptr->_M_obj()); break; case _Op_destroy: { using _Alloc2 = typename _Traits::allocator_type; _Alloc2 __a(__ptr->_M_alloc()); __allocated_ptr<_Alloc2> __guard{__a, const_cast<_Data*>(__ptr)}; __ptr->~_Data(); } break; } } #endif // @} group any _GLIBCXX_END_NAMESPACE_VERSION } // namespace fundamentals_v1 } // namespace experimental } // namespace std #endif // C++14 #endif // _GLIBCXX_EXPERIMENTAL_ANY