any
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// <any> -*- C++ -*-
// Copyright (C) 2014-2021 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 include/any
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_ANY
#define _GLIBCXX_ANY 1
#pragma GCC system_header
#if __cplusplus >= 201703L
#include <typeinfo>
#include <new>
#include <utility>
#include <type_traits>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup utilities
* @{
*/
/**
* @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
}
#define __cpp_lib_any 201606L
/**
* @brief A type-safe container of any type.
*
* An `any` object's state is either empty or it stores a contained object
* of CopyConstructible type.
*
* @since C++17
*/
class any
{
// Holds either pointer to a heap object or the contained object itself.
union _Storage
{
constexpr _Storage() : _M_ptr{nullptr} {}
// Prevent trivial copies of this type, buffer might hold a non-POD.
_Storage(const _Storage&) = delete;
_Storage& operator=(const _Storage&) = delete;
void* _M_ptr;
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))
&& (alignof(_Tp) <= alignof(_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 _VTp = decay_t<_Tp>>
using _Decay_if_not_any = enable_if_t<!is_same_v<_VTp, any>, _VTp>;
/// Emplace with an object created from @p __args as the contained object.
template <typename _Tp, typename... _Args,
typename _Mgr = _Manager<_Tp>>
void __do_emplace(_Args&&... __args)
{
reset();
_Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...);
_M_manager = &_Mgr::_S_manage;
}
/// Emplace with an object created from @p __il and @p __args as
/// the contained object.
template <typename _Tp, typename _Up, typename... _Args,
typename _Mgr = _Manager<_Tp>>
void __do_emplace(initializer_list<_Up> __il, _Args&&... __args)
{
reset();
_Mgr::_S_create(_M_storage, __il, std::forward<_Args>(__args)...);
_M_manager = &_Mgr::_S_manage;
}
template <typename _Res, typename _Tp, typename... _Args>
using __any_constructible
= enable_if<__and_<is_copy_constructible<_Tp>,
is_constructible<_Tp, _Args...>>::value,
_Res>;
template <typename _Tp, typename... _Args>
using __any_constructible_t
= typename __any_constructible<bool, _Tp, _Args...>::type;
template<typename _VTp, typename... _Args>
using __emplace_t
= typename __any_constructible<_VTp&, _VTp, _Args...>::type;
public:
// construct/destruct
/// Default constructor, creates an empty object.
constexpr any() noexcept : _M_manager(nullptr) { }
/// Copy constructor, copies the state of @p __other
any(const any& __other)
{
if (!__other.has_value())
_M_manager = nullptr;
else
{
_Arg __arg;
__arg._M_any = this;
__other._M_manager(_Op_clone, &__other, &__arg);
}
}
/**
* @brief Move constructor, transfer the state from @p __other
*
* @post @c !__other.has_value() (this postcondition is a GNU extension)
*/
any(any&& __other) noexcept
{
if (!__other.has_value())
_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 _Tp, typename _VTp = _Decay_if_not_any<_Tp>,
typename _Mgr = _Manager<_VTp>,
enable_if_t<is_copy_constructible_v<_VTp>
&& !__is_in_place_type_v<_VTp>, bool> = true>
any(_Tp&& __value)
: _M_manager(&_Mgr::_S_manage)
{
_Mgr::_S_create(_M_storage, std::forward<_Tp>(__value));
}
/// Construct with an object created from @p __args as the contained object.
template <typename _Tp, typename... _Args, typename _VTp = decay_t<_Tp>,
typename _Mgr = _Manager<_VTp>,
__any_constructible_t<_VTp, _Args&&...> = false>
explicit
any(in_place_type_t<_Tp>, _Args&&... __args)
: _M_manager(&_Mgr::_S_manage)
{
_Mgr::_S_create(_M_storage, std::forward<_Args>(__args)...);
}
/// Construct with an object created from @p __il and @p __args as
/// the contained object.
template <typename _Tp, typename _Up, typename... _Args,
typename _VTp = decay_t<_Tp>, typename _Mgr = _Manager<_VTp>,
__any_constructible_t<_VTp, initializer_list<_Up>&,
_Args&&...> = false>
explicit
any(in_place_type_t<_Tp>, initializer_list<_Up> __il, _Args&&... __args)
: _M_manager(&_Mgr::_S_manage)
{
_Mgr::_S_create(_M_storage, __il, std::forward<_Args>(__args)...);
}
/// Destructor, calls @c reset()
~any() { reset(); }
// assignments
/// Copy the state of another object.
any&
operator=(const any& __rhs)
{
*this = any(__rhs);
return *this;
}
/**
* @brief Move assignment operator
*
* @post @c !__rhs.has_value() (not guaranteed for other implementations)
*/
any&
operator=(any&& __rhs) noexcept
{
if (!__rhs.has_value())
reset();
else if (this != &__rhs)
{
reset();
_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 _Tp>
enable_if_t<is_copy_constructible<_Decay_if_not_any<_Tp>>::value, any&>
operator=(_Tp&& __rhs)
{
*this = any(std::forward<_Tp>(__rhs));
return *this;
}
/// Emplace with an object created from @p __args as the contained object.
template <typename _Tp, typename... _Args>
__emplace_t<decay_t<_Tp>, _Args...>
emplace(_Args&&... __args)
{
using _VTp = decay_t<_Tp>;
__do_emplace<_VTp>(std::forward<_Args>(__args)...);
return *any::_Manager<_VTp>::_S_access(_M_storage);
}
/// Emplace with an object created from @p __il and @p __args as
/// the contained object.
template <typename _Tp, typename _Up, typename... _Args>
__emplace_t<decay_t<_Tp>, initializer_list<_Up>&, _Args&&...>
emplace(initializer_list<_Up> __il, _Args&&... __args)
{
using _VTp = decay_t<_Tp>;
__do_emplace<_VTp, _Up>(__il, std::forward<_Args>(__args)...);
return *any::_Manager<_VTp>::_S_access(_M_storage);
}
// modifiers
/// If not empty, destroy the contained object.
void reset() noexcept
{
if (has_value())
{
_M_manager(_Op_destroy, this, nullptr);
_M_manager = nullptr;
}
}
/// Exchange state with another object.
void swap(any& __rhs) noexcept
{
if (!has_value() && !__rhs.has_value())
return;
if (has_value() && __rhs.has_value())
{
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 = !has_value() ? this : &__rhs;
any* __full = !has_value() ? &__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 has_value() 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 (!has_value())
return typeid(void);
_Arg __arg;
_M_manager(_Op_get_type_info, this, &__arg);
return *__arg._M_typeinfo;
}
#endif
/// @cond undocumented
template<typename _Tp>
static constexpr bool __is_valid_cast()
{ return __or_<is_reference<_Tp>, is_copy_constructible<_Tp>>::value; }
/// @endcond
private:
enum _Op {
_Op_access, _Op_get_type_info, _Op_clone, _Op_destroy, _Op_xfer
};
union _Arg
{
void* _M_obj;
const std::type_info* _M_typeinfo;
any* _M_any;
};
void (*_M_manager)(_Op, const any*, _Arg*);
_Storage _M_storage;
/// @cond undocumented
template<typename _Tp>
friend void* __any_caster(const any* __any);
/// @endcond
// 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 void
_S_create(_Storage& __storage, _Up&& __value)
{
void* __addr = &__storage._M_buffer;
::new (__addr) _Tp(std::forward<_Up>(__value));
}
template<typename... _Args>
static void
_S_create(_Storage& __storage, _Args&&... __args)
{
void* __addr = &__storage._M_buffer;
::new (__addr) _Tp(std::forward<_Args>(__args)...);
}
static _Tp*
_S_access(const _Storage& __storage)
{
// The contained object is in __storage._M_buffer
const void* __addr = &__storage._M_buffer;
return static_cast<_Tp*>(const_cast<void*>(__addr));
}
};
// 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 void
_S_create(_Storage& __storage, _Up&& __value)
{
__storage._M_ptr = new _Tp(std::forward<_Up>(__value));
}
template<typename... _Args>
static void
_S_create(_Storage& __storage, _Args&&... __args)
{
__storage._M_ptr = new _Tp(std::forward<_Args>(__args)...);
}
static _Tp*
_S_access(const _Storage& __storage)
{
// The contained object is in *__storage._M_ptr
return static_cast<_Tp*>(__storage._M_ptr);
}
};
};
/// Exchange the states of two @c any objects.
inline void swap(any& __x, any& __y) noexcept { __x.swap(__y); }
/// Create an `any` holding a `_Tp` constructed from `__args...`.
template <typename _Tp, typename... _Args>
inline
enable_if_t<is_constructible_v<any, in_place_type_t<_Tp>, _Args...>, any>
make_any(_Args&&... __args)
{
return any(in_place_type<_Tp>, std::forward<_Args>(__args)...);
}
/// Create an `any` holding a `_Tp` constructed from `__il` and `__args...`.
template <typename _Tp, typename _Up, typename... _Args>
inline
enable_if_t<is_constructible_v<any, in_place_type_t<_Tp>,
initializer_list<_Up>&, _Args...>, any>
make_any(initializer_list<_Up> __il, _Args&&... __args)
{
return any(in_place_type<_Tp>, __il, std::forward<_Args>(__args)...);
}
/**
* @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)
{
using _Up = __remove_cvref_t<_ValueType>;
static_assert(any::__is_valid_cast<_ValueType>(),
"Template argument must be a reference or CopyConstructible type");
static_assert(is_constructible_v<_ValueType, const _Up&>,
"Template argument must be constructible from a const value.");
auto __p = any_cast<_Up>(&__any);
if (__p)
return static_cast<_ValueType>(*__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)
{
using _Up = __remove_cvref_t<_ValueType>;
static_assert(any::__is_valid_cast<_ValueType>(),
"Template argument must be a reference or CopyConstructible type");
static_assert(is_constructible_v<_ValueType, _Up&>,
"Template argument must be constructible from an lvalue.");
auto __p = any_cast<_Up>(&__any);
if (__p)
return static_cast<_ValueType>(*__p);
__throw_bad_any_cast();
}
template<typename _ValueType>
inline _ValueType any_cast(any&& __any)
{
using _Up = __remove_cvref_t<_ValueType>;
static_assert(any::__is_valid_cast<_ValueType>(),
"Template argument must be a reference or CopyConstructible type");
static_assert(is_constructible_v<_ValueType, _Up>,
"Template argument must be constructible from an rvalue.");
auto __p = any_cast<_Up>(&__any);
if (__p)
return static_cast<_ValueType>(std::move(*__p));
__throw_bad_any_cast();
}
/// @}
/// @cond undocumented
template<typename _Tp>
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:
if constexpr (!is_same_v<decay_t<_Up>, _Up>)
return nullptr;
// Only copy constructible types can be used for contained values:
else if constexpr (!is_copy_constructible_v<_Up>)
return nullptr;
// First try comparing function addresses, which works without RTTI
else if (__any->_M_manager == &any::_Manager<_Up>::_S_manage
#if __cpp_rtti
|| __any->type() == typeid(_Tp)
#endif
)
{
return any::_Manager<_Up>::_S_access(__any->_M_storage);
}
return nullptr;
}
/// @endcond
/**
* @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 constexpr (is_object_v<_ValueType>)
if (__any)
return static_cast<_ValueType*>(__any_caster<_ValueType>(__any));
return nullptr;
}
template<typename _ValueType>
inline _ValueType* any_cast(any* __any) noexcept
{
if constexpr (is_object_v<_ValueType>)
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);
__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;
}
}
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);
__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;
}
}
/// @}
namespace __detail::__variant
{
template<typename> struct _Never_valueless_alt; // see <variant>
// Provide the strong exception-safety guarantee when emplacing an
// any into a variant.
template<>
struct _Never_valueless_alt<std::any>
: std::true_type
{ };
} // namespace __detail::__variant
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++17
#endif // _GLIBCXX_ANY
new
typeinfo
type_traits
utility
std::conditional_t
typename conditional< _Cond, _Iftrue, _Iffalse >::type conditional_t
Alias template for conditional.
Definition type_traits:2581
std::true_type
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition type_traits:83
std::enable_if_t
typename enable_if< _Cond, _Tp >::type enable_if_t
Alias template for enable_if.
Definition type_traits:2577
std::decay_t
typename decay< _Tp >::type decay_t
Alias template for decay.
Definition type_traits:2573
std::remove_cv_t
typename remove_cv< _Tp >::type remove_cv_t
Alias template for remove_cv.
Definition type_traits:1576
std::make_any
enable_if_t< is_constructible_v< any, in_place_type_t< _Tp >, _Args... >, any > make_any(_Args &&... __args)
Create an any holding a _Tp constructed from __args....
Definition any:434
std::any_cast
_ValueType any_cast(const any &__any)
Access the contained object.
Definition any:460
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:104
std::swap
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition any:428
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:77
std
ISO C++ entities toplevel namespace is std.
std::initializer_list
initializer_list
Definition initializer_list:48
std::type_info
Part of RTTI.
Definition typeinfo:89
std::bad_any_cast
Exception class thrown by a failed any_cast.
Definition any:55
std::bad_any_cast::what
virtual const char * what() const noexcept
Definition any:57
std::any
A type-safe container of any type.
Definition any:80
std::any::type
const type_info & type() const noexcept
The typeid of the contained object, or typeid(void) if empty.
Definition any:328
std::any::emplace
__emplace_t< decay_t< _Tp >, _Args... > emplace(_Args &&... __args)
Emplace with an object created from __args as the contained object.
Definition any:261
std::any::any
any(const any &__other)
Copy constructor, copies the state of __other.
Definition any:152
std::any::~any
~any()
Destructor, calls reset().
Definition any:217
std::any::any
constexpr any() noexcept
Default constructor, creates an empty object.
Definition any:149
std::any::reset
void reset() noexcept
If not empty, destroy the contained object.
Definition any:282
std::any::swap
void swap(any &__rhs) noexcept
Exchange state with another object.
Definition any:292
std::any::has_value
bool has_value() const noexcept
Reports whether there is a contained object or not.
Definition any:324
std::any::operator=
any & operator=(const any &__rhs)
Copy the state of another object.
Definition any:223
std::is_constructible
is_constructible
Definition type_traits:954
std::is_copy_constructible
is_copy_constructible
Definition type_traits:986
std::aligned_storage
Alignment type.
Definition type_traits:2077
std::enable_if
Define a member typedef type only if a boolean constant is true.
Definition type_traits:2192