// <experimental/any> -*- C++ -*-
-// Copyright (C) 2014-2015 Free Software Foundation, Inc.
+// Copyright (C) 2014-2020 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
/** @file experimental/any
* This is a TS C++ Library header.
+ * @ingroup libfund-ts
*/
#ifndef _GLIBCXX_EXPERIMENTAL_ANY
#pragma GCC system_header
-#if __cplusplus <= 201103L
-# include <bits/c++14_warning.h>
-#else
+#if __cplusplus >= 201402L
#include <typeinfo>
#include <new>
#include <utility>
#include <type_traits>
+#include <experimental/bits/lfts_config.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
namespace experimental
{
inline namespace fundamentals_v1
{
-_GLIBCXX_BEGIN_NAMESPACE_VERSION
-
/**
* @defgroup any Type-safe container of any type
- * @ingroup experimental
+ * @ingroup libfund-ts
*
* A type-safe container for single values of value types, as
* described in n3804 "Any Library Proposal (Revision 3)".
virtual const char* what() const noexcept { return "bad any_cast"; }
};
+ /// @cond undocumented
[[gnu::noreturn]] inline void __throw_bad_any_cast()
{
#if __cpp_exceptions
__builtin_abort();
#endif
}
+ /// @endcond
/**
* @brief A type-safe container of any type.
// Holds either pointer to a heap object or the contained object itself.
union _Storage
{
+ // This constructor intentionally doesn't initialize anything.
+ _Storage() = default;
+
+ // Prevent trivial copies of this type, buffer might hold a non-POD.
+ _Storage(const _Storage&) = delete;
+ _Storage& operator=(const _Storage&) = delete;
+
void* _M_ptr;
- std::aligned_storage<sizeof(_M_ptr), sizeof(_M_ptr)>::type _M_buffer;
+ aligned_storage<sizeof(_M_ptr), alignof(void*)>::type _M_buffer;
};
template<typename _Tp, typename _Safe = is_nothrow_move_constructible<_Tp>,
- bool _Fits = (sizeof(_Tp) <= sizeof(_Storage))>
+ bool _Fits = (sizeof(_Tp) <= sizeof(_Storage))
+ && (alignof(_Tp) <= alignof(_Storage))>
using _Internal = std::integral_constant<bool, _Safe::value && _Fits>;
template<typename _Tp>
any() noexcept : _M_manager(nullptr) { }
/// Copy constructor, copies the state of @p __other
- any(const any& __other) : _M_manager(__other._M_manager)
+ any(const any& __other)
{
- if (!__other.empty())
+ if (__other.empty())
+ _M_manager = nullptr;
+ else
{
_Arg __arg;
__arg._M_any = this;
- _M_manager(_Op_clone, &__other, &__arg);
+ __other._M_manager(_Op_clone, &__other, &__arg);
}
}
/**
* @brief Move constructor, transfer the state from @p __other
*
- * @post @c __other.empty() (not guaranteed for other implementations)
+ * @post @c __other.empty() (this postcondition is a GNU extension)
*/
any(any&& __other) noexcept
- : _M_manager(__other._M_manager),
- _M_storage(__other._M_storage)
- { __other._M_manager = nullptr; }
+ {
+ if (__other.empty())
+ _M_manager = nullptr;
+ else
+ {
+ _Arg __arg;
+ __arg._M_any = this;
+ __other._M_manager(_Op_xfer, &__other, &__arg);
+ }
+ }
+
+ /// Construct with a copy of @p __value as the contained object.
+ template <typename _ValueType, typename _Tp = _Decay<_ValueType>,
+ typename _Mgr = _Manager<_Tp>,
+ typename enable_if<is_constructible<_Tp, _ValueType&&>::value,
+ bool>::type = true>
+ any(_ValueType&& __value)
+ : _M_manager(&_Mgr::_S_manage)
+ {
+ _Mgr::_S_create(_M_storage, std::forward<_ValueType>(__value));
+ static_assert(is_copy_constructible<_Tp>::value,
+ "The contained object must be CopyConstructible");
+ }
/// Construct with a copy of @p __value as the contained object.
template <typename _ValueType, typename _Tp = _Decay<_ValueType>,
- typename _Mgr = _Manager<_Tp>>
+ typename _Mgr = _Manager<_Tp>,
+ typename enable_if<!is_constructible<_Tp, _ValueType&&>::value,
+ bool>::type = false>
any(_ValueType&& __value)
- : _M_manager(&_Mgr::_S_manage),
- _M_storage(_Mgr::_S_create(std::forward<_ValueType>(__value)))
+ : _M_manager(&_Mgr::_S_manage)
{
+ _Mgr::_S_create(_M_storage, __value);
static_assert(is_copy_constructible<_Tp>::value,
"The contained object must be CopyConstructible");
}
// assignments
- /// Copy the state of
+ /// Copy the state of another object.
any& operator=(const any& __rhs)
{
- any(__rhs).swap(*this);
+ *this = any(__rhs);
return *this;
}
*/
any& operator=(any&& __rhs) noexcept
{
- any(std::move(__rhs)).swap(*this);
+ if (__rhs.empty())
+ clear();
+ else if (this != &__rhs)
+ {
+ clear();
+ _Arg __arg;
+ __arg._M_any = this;
+ __rhs._M_manager(_Op_xfer, &__rhs, &__arg);
+ }
return *this;
}
/// Store a copy of @p __rhs as the contained object.
template<typename _ValueType>
- any& operator=(_ValueType&& __rhs)
+ enable_if_t<!is_same<any, decay_t<_ValueType>>::value, any&>
+ operator=(_ValueType&& __rhs)
{
- any(std::forward<_ValueType>(__rhs)).swap(*this);
+ *this = any(std::forward<_ValueType>(__rhs));
return *this;
}
/// Exchange state with another object.
void swap(any& __rhs) noexcept
{
- std::swap(_M_manager, __rhs._M_manager);
- std::swap(_M_storage, __rhs._M_storage);
+ if (empty() && __rhs.empty())
+ return;
+
+ if (!empty() && !__rhs.empty())
+ {
+ if (this == &__rhs)
+ return;
+
+ any __tmp;
+ _Arg __arg;
+ __arg._M_any = &__tmp;
+ __rhs._M_manager(_Op_xfer, &__rhs, &__arg);
+ __arg._M_any = &__rhs;
+ _M_manager(_Op_xfer, this, &__arg);
+ __arg._M_any = this;
+ __tmp._M_manager(_Op_xfer, &__tmp, &__arg);
+ }
+ else
+ {
+ any* __empty = empty() ? this : &__rhs;
+ any* __full = empty() ? &__rhs : this;
+ _Arg __arg;
+ __arg._M_any = __empty;
+ __full->_M_manager(_Op_xfer, __full, &__arg);
+ }
}
// observers
/// Reports whether there is a contained object or not.
- bool empty() const noexcept { return _M_manager == nullptr; }
+ _GLIBCXX_NODISCARD bool empty() const noexcept { return _M_manager == nullptr; }
#if __cpp_rtti
/// The @c typeid of the contained object, or @c typeid(void) if empty.
{ return __or_<is_reference<_Tp>, is_copy_constructible<_Tp>>::value; }
private:
- enum _Op { _Op_access, _Op_get_type_info, _Op_clone, _Op_destroy };
+ enum _Op {
+ _Op_access, _Op_get_type_info, _Op_clone, _Op_destroy, _Op_xfer
+ };
union _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;
- }
+ friend enable_if_t<is_object<_Tp>::value, void*>
+ __any_caster(const any* __any);
// Manage in-place contained object.
template<typename _Tp>
_S_manage(_Op __which, const any* __anyp, _Arg* __arg);
template<typename _Up>
- static _Storage
- _S_create(_Up&& __value)
+ static void
+ _S_create(_Storage& __storage, _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));
}
};
_S_manage(_Op __which, const any* __anyp, _Arg* __arg);
template<typename _Up>
- static _Storage
- _S_create(_Up&& __value)
+ static void
+ _S_create(_Storage& __storage, _Up&& __value)
{
- _Storage __storage;
__storage._M_ptr = new _Tp(std::forward<_Up>(__value));
- return __storage;
}
};
};
__throw_bad_any_cast();
}
- template<typename _ValueType>
+ template<typename _ValueType,
+ typename enable_if<!is_move_constructible<_ValueType>::value
+ || is_lvalue_reference<_ValueType>::value,
+ bool>::type = true>
inline _ValueType any_cast(any&& __any)
{
static_assert(any::__is_valid_cast<_ValueType>(),
return *__p;
__throw_bad_any_cast();
}
+
+ template<typename _ValueType,
+ typename enable_if<is_move_constructible<_ValueType>::value
+ && !is_lvalue_reference<_ValueType>::value,
+ bool>::type = false>
+ 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 std::move(*__p);
+ __throw_bad_any_cast();
+ }
// @}
+ /// @cond undocumented
+ template<typename _Tp>
+ enable_if_t<is_object<_Tp>::value, void*>
+ __any_caster(const any* __any)
+ {
+ // any_cast<T> returns non-null if __any->type() == typeid(T) and
+ // typeid(T) ignores cv-qualifiers so remove them:
+ using _Up = remove_cv_t<_Tp>;
+ // The contained value has a decayed type, so if decay_t<U> is not U,
+ // then it's not possible to have a contained value of type U.
+ using __does_not_decay = is_same<decay_t<_Up>, _Up>;
+ // Only copy constructible types can be used for contained values.
+ using __is_copyable = is_copy_constructible<_Up>;
+ // If the type _Tp could never be stored in an any we don't want to
+ // instantiate _Manager<_Tp>, so use _Manager<any::_Op> instead, which
+ // is explicitly specialized and has a no-op _S_manage function.
+ using _Vp = conditional_t<__and_<__does_not_decay, __is_copyable>::value,
+ _Up, any::_Op>;
+ // First try comparing function addresses, which works without RTTI
+ if (__any->_M_manager == &any::_Manager<_Vp>::_S_manage
+#if __cpp_rtti
+ || __any->type() == typeid(_Tp)
+#endif
+ )
+ {
+ any::_Arg __arg;
+ __any->_M_manager(any::_Op_access, __any, &__arg);
+ return __arg._M_obj;
+ }
+ return nullptr;
+ }
+
+ // This overload exists so that std::any_cast<void(*)()>(a) is well-formed.
+ template<typename _Tp>
+ enable_if_t<!is_object<_Tp>::value, _Tp*>
+ __any_caster(const any*) noexcept
+ { return nullptr; }
+ /// @endcond
+
/**
* @brief Access the contained object.
*
break;
case _Op_clone:
::new(&__arg->_M_any->_M_storage._M_buffer) _Tp(*__ptr);
+ __arg->_M_any->_M_manager = __any->_M_manager;
break;
case _Op_destroy:
__ptr->~_Tp();
break;
+ case _Op_xfer:
+ ::new(&__arg->_M_any->_M_storage._M_buffer) _Tp
+ (std::move(*const_cast<_Tp*>(__ptr)));
+ __ptr->~_Tp();
+ __arg->_M_any->_M_manager = __any->_M_manager;
+ const_cast<any*>(__any)->_M_manager = nullptr;
+ break;
}
}
break;
case _Op_clone:
__arg->_M_any->_M_storage._M_ptr = new _Tp(*__ptr);
+ __arg->_M_any->_M_manager = __any->_M_manager;
break;
case _Op_destroy:
delete __ptr;
break;
+ case _Op_xfer:
+ __arg->_M_any->_M_storage._M_ptr = __any->_M_storage._M_ptr;
+ __arg->_M_any->_M_manager = __any->_M_manager;
+ const_cast<any*>(__any)->_M_manager = nullptr;
+ break;
}
}
+ // Dummy specialization used by __any_caster.
+ template<>
+ struct any::_Manager_internal<any::_Op>
+ {
+ static void
+ _S_manage(_Op, const any*, _Arg*) { }
+ };
+
// @} group any
-_GLIBCXX_END_NAMESPACE_VERSION
} // namespace fundamentals_v1
} // namespace experimental
+
+_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++14
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