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- // <experimental/any> -*- C++ -*-
- // Copyright (C) 2014-2015 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
- // <http://www.gnu.org/licenses/>.
- /** @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 <bits/c++14_warning.h>
- #else
- #include <typeinfo>
- #include <new>
- #include <utility>
- #include <type_traits>
- 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 201411
- /**
- * @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()
- {
- #if __cpp_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<sizeof(_M_ptr), sizeof(_M_ptr)>::type _M_buffer;
- };
- template<typename _Tp, typename _Safe = is_trivially_copyable<_Tp>,
- bool _Fits = (sizeof(_Tp) <= sizeof(_Storage))>
- using _Internal = std::integral_constant<bool, _Safe::value && _Fits>;
- template<typename _Tp>
- struct _Manager_internal; // uses small-object optimization
- template<typename _Tp>
- struct _Manager_external; // creates contained object on the heap
- template<typename _Tp>
- using _Manager = conditional_t<_Internal<_Tp>::value,
- _Manager_internal<_Tp>,
- _Manager_external<_Tp>>;
- template<typename _Tp, typename _Decayed = decay_t<_Tp>>
- using _Decay = enable_if_t<!is_same<_Decayed, any>::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 _ValueType, typename _Tp = _Decay<_ValueType>,
- 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");
- }
- /// 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<typename _ValueType>
- 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; }
- #if __cpp_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<typename _Tp>
- static constexpr bool __is_valid_cast()
- { return __or_<is_reference<_Tp>, 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<typename _Tp>
- friend void* __any_caster(const any* __any)
- {
- if (__any->_M_manager != &_Manager<decay_t<_Tp>>::_S_manage)
- return nullptr;
- _Arg __arg;
- __any->_M_manager(_Op_access, __any, &__arg);
- return __arg._M_obj;
- }
- // Manage in-place contained object.
- template<typename _Tp>
- struct _Manager_internal
- {
- static void
- _S_manage(_Op __which, const any* __anyp, _Arg* __arg);
- template<typename _Up>
- static _Storage
- _S_create(_Up&& __value)
- {
- _Storage __storage;
- void* __addr = &__storage._M_buffer;
- ::new (__addr) _Tp(std::forward<_Up>(__value));
- return __storage;
- }
- template<typename _Alloc, typename _Up>
- static _Storage
- _S_alloc(const _Alloc&, _Up&& __value)
- {
- return _S_create(std::forward<_Up>(__value));
- }
- };
- // Manage external contained object.
- template<typename _Tp>
- struct _Manager_external
- {
- static void
- _S_manage(_Op __which, const any* __anyp, _Arg* __arg);
- template<typename _Up>
- static _Storage
- _S_create(_Up&& __value)
- {
- _Storage __storage;
- __storage._M_ptr = new _Tp(std::forward<_Up>(__value));
- return __storage;
- }
- };
- };
- /// 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 <code>
- * __any.type() != typeid(remove_reference_t<_ValueType>)
- * </code>
- */
- template<typename _ValueType>
- 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<add_const_t<remove_reference_t<_ValueType>>>(&__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 <code>
- * __any.type() != typeid(remove_reference_t<_ValueType>)
- * </code>
- *
- * @{
- */
- template<typename _ValueType>
- 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<remove_reference_t<_ValueType>>(&__any);
- if (__p)
- return *__p;
- __throw_bad_any_cast();
- }
- template<typename _ValueType>
- 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<remove_reference_t<_ValueType>>(&__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 <code>
- * __any != nullptr && __any.type() == typeid(_ValueType)
- * </code>, otherwise a null pointer.
- *
- * @{
- */
- template<typename _ValueType>
- inline const _ValueType* any_cast(const any* __any) noexcept
- {
- if (__any)
- return static_cast<_ValueType*>(__any_caster<_ValueType>(__any));
- return nullptr;
- }
- template<typename _ValueType>
- inline _ValueType* any_cast(any* __any) noexcept
- {
- if (__any)
- return static_cast<_ValueType*>(__any_caster<_ValueType>(__any));
- return nullptr;
- }
- // @}
- template<typename _Tp>
- 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<const _Tp*>(&__any->_M_storage._M_buffer);
- switch (__which)
- {
- case _Op_access:
- __arg->_M_obj = const_cast<_Tp*>(__ptr);
- break;
- case _Op_get_type_info:
- #if __cpp_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<typename _Tp>
- 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<const _Tp*>(__any->_M_storage._M_ptr);
- switch (__which)
- {
- case _Op_access:
- __arg->_M_obj = const_cast<_Tp*>(__ptr);
- break;
- case _Op_get_type_info:
- #if __cpp_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;
- }
- }
- // @} group any
- _GLIBCXX_END_NAMESPACE_VERSION
- } // namespace fundamentals_v1
- } // namespace experimental
- } // namespace std
- #endif // C++14
- #endif // _GLIBCXX_EXPERIMENTAL_ANY
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