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gcc/libstdc++-v3/include/bits/shared_ptr.h
Jonathan Wakely b2343559f2 Add array support to std::shared_ptr for C++17 
* doc/xml/manual/status_cxx2017.xml: Update status.
	* doc/html/manual/status.html: Regenerate.
	* include/bits/shared_ptr.h (shared_ptr(unique_ptr<_Yp, _Del>)): Add
	extension constructor to maintain C++14 behaviour.
	* include/bits/shared_ptr_base.h (__sp_array_delete): Add new struct.
	(__shared_count(_Ptr, false_type), __shared_count(_Ptr, true_type)):
	New constructors.
	(__sp_compatible_with, __sp_is_constructible): Add specializations
	for array support.
	(__sp_is_constructible_arr, __sp_is_constructible_arrN): New helpers.
	(__shared_ptr_access): New base class for observer member functions.
	(__shared_ptr::element_type): Use remove_extent.
	(__shared_ptr::_UniqCompatible): Add __sp_compatible_with check.
	(__shared_ptr(_Yp*)): Use tag dispatching to call new __shared_count
	constructor.
	(__shared_ptr(unique_ptr<_Yp, _Del>)): Add extension constructor.
	(__shared_ptr::operator*, __shared_ptr::operator->): Remove and
	inherit from __shared_ptr_access base class.
	(__shared_ptr::__has_esft_base): Return false for array types.
	(__weak_ptr::element_type): Use remove_extent.
	* include/experimental/bits/shared_ptr.h (__libfund_v1): Remove.
	(__shared_ptr<__libfund_v1<_Tp>>): Remove specializations.
	(__wak_ptr<__libfund_v1<_Tp>>): Likewise.
	(experimental::__sp_compatible_v): Redefine using
	__sp_compatible_with.
	(experimental::__sp_is_constructible_v): Redefine using
	__sp_is_constructible.
	(get_deleter, operator<<): Change argument from __shared_ptr to
	shared_ptr.
	* testsuite/20_util/shared_ptr/cons/array.cc: New test.
	* testsuite/20_util/shared_ptr/cons/unique_ptr_array.cc: Adjust for
	new behaviour.
	* testsuite/20_util/shared_ptr/observers/array.cc: Test observers for
	arrays.
	* testsuite/20_util/shared_ptr/observers/array_neg.cc: New test.

From-SVN: r242369
2016-11-13 22:57:45 +00:00

716 lines
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// shared_ptr and weak_ptr implementation -*- C++ -*-
// Copyright (C) 2007-2016 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/>.
// GCC Note: Based on files from version 1.32.0 of the Boost library.
// shared_count.hpp
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
// shared_ptr.hpp
// Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
// Copyright (C) 2001, 2002, 2003 Peter Dimov
// weak_ptr.hpp
// Copyright (C) 2001, 2002, 2003 Peter Dimov
// enable_shared_from_this.hpp
// Copyright (C) 2002 Peter Dimov
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
/** @file
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{memory}
*/
#ifndef _SHARED_PTR_H
#define _SHARED_PTR_H 1
#include <bits/shared_ptr_base.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup pointer_abstractions
* @{
*/
/// 20.7.2.2.11 shared_ptr I/O
template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
inline std::basic_ostream<_Ch, _Tr>&
operator<<(std::basic_ostream<_Ch, _Tr>& __os,
const __shared_ptr<_Tp, _Lp>& __p)
{
__os << __p.get();
return __os;
}
/// 20.7.2.2.10 shared_ptr get_deleter
template<typename _Del, typename _Tp, _Lock_policy _Lp>
inline _Del*
get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept
{
#if __cpp_rtti
return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
#else
return 0;
#endif
}
/**
* @brief A smart pointer with reference-counted copy semantics.
*
* The object pointed to is deleted when the last shared_ptr pointing to
* it is destroyed or reset.
*/
template<typename _Tp>
class shared_ptr : public __shared_ptr<_Tp>
{
template<typename... _Args>
using _Constructible = typename enable_if<
is_constructible<__shared_ptr<_Tp>, _Args...>::value
>::type;
template<typename _Arg>
using _Assignable = typename enable_if<
is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr&
>::type;
public:
using element_type = typename __shared_ptr<_Tp>::element_type;
#if __cplusplus > 201402L
# define __cpp_lib_shared_ptr_weak_type 201606
using weak_type = weak_ptr<_Tp>;
#endif
/**
* @brief Construct an empty %shared_ptr.
* @post use_count()==0 && get()==0
*/
constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { }
shared_ptr(const shared_ptr&) noexcept = default;
/**
* @brief Construct a %shared_ptr that owns the pointer @a __p.
* @param __p A pointer that is convertible to element_type*.
* @post use_count() == 1 && get() == __p
* @throw std::bad_alloc, in which case @c delete @a __p is called.
*/
template<typename _Yp, typename = _Constructible<_Yp*>>
explicit
shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { }
/**
* @brief Construct a %shared_ptr that owns the pointer @a __p
* and the deleter @a __d.
* @param __p A pointer.
* @param __d A deleter.
* @post use_count() == 1 && get() == __p
* @throw std::bad_alloc, in which case @a __d(__p) is called.
*
* Requirements: _Deleter's copy constructor and destructor must
* not throw
*
* __shared_ptr will release __p by calling __d(__p)
*/
template<typename _Yp, typename _Deleter,
typename = _Constructible<_Yp*, _Deleter>>
shared_ptr(_Yp* __p, _Deleter __d)
: __shared_ptr<_Tp>(__p, __d) { }
/**
* @brief Construct a %shared_ptr that owns a null pointer
* and the deleter @a __d.
* @param __p A null pointer constant.
* @param __d A deleter.
* @post use_count() == 1 && get() == __p
* @throw std::bad_alloc, in which case @a __d(__p) is called.
*
* Requirements: _Deleter's copy constructor and destructor must
* not throw
*
* The last owner will call __d(__p)
*/
template<typename _Deleter>
shared_ptr(nullptr_t __p, _Deleter __d)
: __shared_ptr<_Tp>(__p, __d) { }
/**
* @brief Construct a %shared_ptr that owns the pointer @a __p
* and the deleter @a __d.
* @param __p A pointer.
* @param __d A deleter.
* @param __a An allocator.
* @post use_count() == 1 && get() == __p
* @throw std::bad_alloc, in which case @a __d(__p) is called.
*
* Requirements: _Deleter's copy constructor and destructor must
* not throw _Alloc's copy constructor and destructor must not
* throw.
*
* __shared_ptr will release __p by calling __d(__p)
*/
template<typename _Yp, typename _Deleter, typename _Alloc,
typename = _Constructible<_Yp*, _Deleter, _Alloc>>
shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
: __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
/**
* @brief Construct a %shared_ptr that owns a null pointer
* and the deleter @a __d.
* @param __p A null pointer constant.
* @param __d A deleter.
* @param __a An allocator.
* @post use_count() == 1 && get() == __p
* @throw std::bad_alloc, in which case @a __d(__p) is called.
*
* Requirements: _Deleter's copy constructor and destructor must
* not throw _Alloc's copy constructor and destructor must not
* throw.
*
* The last owner will call __d(__p)
*/
template<typename _Deleter, typename _Alloc>
shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
: __shared_ptr<_Tp>(__p, __d, std::move(__a)) { }
// Aliasing constructor
/**
* @brief Constructs a %shared_ptr instance that stores @a __p
* and shares ownership with @a __r.
* @param __r A %shared_ptr.
* @param __p A pointer that will remain valid while @a *__r is valid.
* @post get() == __p && use_count() == __r.use_count()
*
* This can be used to construct a @c shared_ptr to a sub-object
* of an object managed by an existing @c shared_ptr.
*
* @code
* shared_ptr< pair<int,int> > pii(new pair<int,int>());
* shared_ptr<int> pi(pii, &pii->first);
* assert(pii.use_count() == 2);
* @endcode
*/
template<typename _Yp>
shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept
: __shared_ptr<_Tp>(__r, __p) { }
/**
* @brief If @a __r is empty, constructs an empty %shared_ptr;
* otherwise construct a %shared_ptr that shares ownership
* with @a __r.
* @param __r A %shared_ptr.
* @post get() == __r.get() && use_count() == __r.use_count()
*/
template<typename _Yp,
typename = _Constructible<const shared_ptr<_Yp>&>>
shared_ptr(const shared_ptr<_Yp>& __r) noexcept
: __shared_ptr<_Tp>(__r) { }
/**
* @brief Move-constructs a %shared_ptr instance from @a __r.
* @param __r A %shared_ptr rvalue.
* @post *this contains the old value of @a __r, @a __r is empty.
*/
shared_ptr(shared_ptr&& __r) noexcept
: __shared_ptr<_Tp>(std::move(__r)) { }
/**
* @brief Move-constructs a %shared_ptr instance from @a __r.
* @param __r A %shared_ptr rvalue.
* @post *this contains the old value of @a __r, @a __r is empty.
*/
template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>>
shared_ptr(shared_ptr<_Yp>&& __r) noexcept
: __shared_ptr<_Tp>(std::move(__r)) { }
/**
* @brief Constructs a %shared_ptr that shares ownership with @a __r
* and stores a copy of the pointer stored in @a __r.
* @param __r A weak_ptr.
* @post use_count() == __r.use_count()
* @throw bad_weak_ptr when __r.expired(),
* in which case the constructor has no effect.
*/
template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
explicit shared_ptr(const weak_ptr<_Yp>& __r)
: __shared_ptr<_Tp>(__r) { }
#if _GLIBCXX_USE_DEPRECATED
template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>>
shared_ptr(auto_ptr<_Yp>&& __r);
#endif
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2399. shared_ptr's constructor from unique_ptr should be constrained
template<typename _Yp, typename _Del,
typename = _Constructible<unique_ptr<_Yp, _Del>>>
shared_ptr(unique_ptr<_Yp, _Del>&& __r)
: __shared_ptr<_Tp>(std::move(__r)) { }
#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
// This non-standard constructor exists to support conversions that
// were possible in C++11 and C++14 but are ill-formed in C++17.
// If an exception is thrown this constructor has no effect.
template<typename _Yp, typename _Del,
_Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0>
shared_ptr(unique_ptr<_Yp, _Del>&& __r)
: __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { }
#endif
/**
* @brief Construct an empty %shared_ptr.
* @post use_count() == 0 && get() == nullptr
*/
constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { }
shared_ptr& operator=(const shared_ptr&) noexcept = default;
template<typename _Yp>
_Assignable<const shared_ptr<_Yp>&>
operator=(const shared_ptr<_Yp>& __r) noexcept
{
this->__shared_ptr<_Tp>::operator=(__r);
return *this;
}
#if _GLIBCXX_USE_DEPRECATED
template<typename _Yp>
_Assignable<auto_ptr<_Yp>>
operator=(auto_ptr<_Yp>&& __r)
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
#endif
shared_ptr&
operator=(shared_ptr&& __r) noexcept
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
template<class _Yp>
_Assignable<shared_ptr<_Yp>>
operator=(shared_ptr<_Yp>&& __r) noexcept
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
template<typename _Yp, typename _Del>
_Assignable<unique_ptr<_Yp, _Del>>
operator=(unique_ptr<_Yp, _Del>&& __r)
{
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
private:
// This constructor is non-standard, it is used by allocate_shared.
template<typename _Alloc, typename... _Args>
shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
_Args&&... __args)
: __shared_ptr<_Tp>(__tag, __a, std::forward<_Args>(__args)...)
{ }
template<typename _Yp, typename _Alloc, typename... _Args>
friend shared_ptr<_Yp>
allocate_shared(const _Alloc& __a, _Args&&... __args);
// This constructor is non-standard, it is used by weak_ptr::lock().
shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t)
: __shared_ptr<_Tp>(__r, std::nothrow) { }
friend class weak_ptr<_Tp>;
};
// 20.7.2.2.7 shared_ptr comparisons
template<typename _Tp, typename _Up>
inline bool
operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{ return __a.get() == __b.get(); }
template<typename _Tp>
inline bool
operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{ return !__a; }
template<typename _Tp>
inline bool
operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
{ return !__a; }
template<typename _Tp, typename _Up>
inline bool
operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{ return __a.get() != __b.get(); }
template<typename _Tp>
inline bool
operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{ return (bool)__a; }
template<typename _Tp>
inline bool
operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
{ return (bool)__a; }
template<typename _Tp, typename _Up>
inline bool
operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{
using _Tp_elt = typename shared_ptr<_Tp>::element_type;
using _Up_elt = typename shared_ptr<_Up>::element_type;
using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
return less<_Vp>()(__a.get(), __b.get());
}
template<typename _Tp>
inline bool
operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{
using _Tp_elt = typename shared_ptr<_Tp>::element_type;
return less<_Tp_elt*>()(__a.get(), nullptr);
}
template<typename _Tp>
inline bool
operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
{
using _Tp_elt = typename shared_ptr<_Tp>::element_type;
return less<_Tp_elt*>()(nullptr, __a.get());
}
template<typename _Tp, typename _Up>
inline bool
operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{ return !(__b < __a); }
template<typename _Tp>
inline bool
operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{ return !(nullptr < __a); }
template<typename _Tp>
inline bool
operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
{ return !(__a < nullptr); }
template<typename _Tp, typename _Up>
inline bool
operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{ return (__b < __a); }
template<typename _Tp>
inline bool
operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{ return nullptr < __a; }
template<typename _Tp>
inline bool
operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
{ return __a < nullptr; }
template<typename _Tp, typename _Up>
inline bool
operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
{ return !(__a < __b); }
template<typename _Tp>
inline bool
operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{ return !(__a < nullptr); }
template<typename _Tp>
inline bool
operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
{ return !(nullptr < __a); }
template<typename _Tp>
struct less<shared_ptr<_Tp>> : public _Sp_less<shared_ptr<_Tp>>
{ };
// 20.7.2.2.8 shared_ptr specialized algorithms.
template<typename _Tp>
inline void
swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
{ __a.swap(__b); }
// 20.7.2.2.9 shared_ptr casts.
template<typename _Tp, typename _Up>
inline shared_ptr<_Tp>
static_pointer_cast(const shared_ptr<_Up>& __r) noexcept
{
using _Sp = shared_ptr<_Tp>;
return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
}
template<typename _Tp, typename _Up>
inline shared_ptr<_Tp>
const_pointer_cast(const shared_ptr<_Up>& __r) noexcept
{
using _Sp = shared_ptr<_Tp>;
return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
}
template<typename _Tp, typename _Up>
inline shared_ptr<_Tp>
dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept
{
using _Sp = shared_ptr<_Tp>;
if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
return _Sp(__r, __p);
return _Sp();
}
#if __cplusplus > 201402L
template<typename _Tp, typename _Up>
inline shared_ptr<_Tp>
reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept
{
using _Sp = shared_ptr<_Tp>;
return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
}
#endif
/**
* @brief A smart pointer with weak semantics.
*
* With forwarding constructors and assignment operators.
*/
template<typename _Tp>
class weak_ptr : public __weak_ptr<_Tp>
{
template<typename _Arg>
using _Constructible = typename enable_if<
is_constructible<__weak_ptr<_Tp>, _Arg>::value
>::type;
template<typename _Arg>
using _Assignable = typename enable_if<
is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr&
>::type;
public:
constexpr weak_ptr() noexcept = default;
template<typename _Yp,
typename = _Constructible<const shared_ptr<_Yp>&>>
weak_ptr(const shared_ptr<_Yp>& __r) noexcept
: __weak_ptr<_Tp>(__r) { }
weak_ptr(const weak_ptr&) noexcept = default;
template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
weak_ptr(const weak_ptr<_Yp>& __r) noexcept
: __weak_ptr<_Tp>(__r) { }
weak_ptr(weak_ptr&&) noexcept = default;
template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>>
weak_ptr(weak_ptr<_Yp>&& __r) noexcept
: __weak_ptr<_Tp>(std::move(__r)) { }
weak_ptr&
operator=(const weak_ptr& __r) noexcept = default;
template<typename _Yp>
_Assignable<const weak_ptr<_Yp>&>
operator=(const weak_ptr<_Yp>& __r) noexcept
{
this->__weak_ptr<_Tp>::operator=(__r);
return *this;
}
template<typename _Yp>
_Assignable<const shared_ptr<_Yp>&>
operator=(const shared_ptr<_Yp>& __r) noexcept
{
this->__weak_ptr<_Tp>::operator=(__r);
return *this;
}
weak_ptr&
operator=(weak_ptr&& __r) noexcept = default;
template<typename _Yp>
_Assignable<weak_ptr<_Yp>>
operator=(weak_ptr<_Yp>&& __r) noexcept
{
this->__weak_ptr<_Tp>::operator=(std::move(__r));
return *this;
}
shared_ptr<_Tp>
lock() const noexcept
{ return shared_ptr<_Tp>(*this, std::nothrow); }
};
// 20.7.2.3.6 weak_ptr specialized algorithms.
template<typename _Tp>
inline void
swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
{ __a.swap(__b); }
/// Primary template owner_less
template<typename _Tp = void>
struct owner_less;
/// Void specialization of owner_less
template<>
struct owner_less<void> : _Sp_owner_less<void, void>
{ };
/// Partial specialization of owner_less for shared_ptr.
template<typename _Tp>
struct owner_less<shared_ptr<_Tp>>
: public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
{ };
/// Partial specialization of owner_less for weak_ptr.
template<typename _Tp>
struct owner_less<weak_ptr<_Tp>>
: public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
{ };
/**
* @brief Base class allowing use of member function shared_from_this.
*/
template<typename _Tp>
class enable_shared_from_this
{
protected:
constexpr enable_shared_from_this() noexcept { }
enable_shared_from_this(const enable_shared_from_this&) noexcept { }
enable_shared_from_this&
operator=(const enable_shared_from_this&) noexcept
{ return *this; }
~enable_shared_from_this() { }
public:
shared_ptr<_Tp>
shared_from_this()
{ return shared_ptr<_Tp>(this->_M_weak_this); }
shared_ptr<const _Tp>
shared_from_this() const
{ return shared_ptr<const _Tp>(this->_M_weak_this); }
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
#define __cpp_lib_enable_shared_from_this 201603
weak_ptr<_Tp>
weak_from_this() noexcept
{ return this->_M_weak_this; }
weak_ptr<const _Tp>
weak_from_this() const noexcept
{ return this->_M_weak_this; }
#endif
private:
template<typename _Tp1>
void
_M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
{ _M_weak_this._M_assign(__p, __n); }
// Found by ADL when this is an associated class.
friend const enable_shared_from_this*
__enable_shared_from_this_base(const __shared_count<>&,
const enable_shared_from_this* __p)
{ return __p; }
template<typename, _Lock_policy>
friend class __shared_ptr;
mutable weak_ptr<_Tp> _M_weak_this;
};
/**
* @brief Create an object that is owned by a shared_ptr.
* @param __a An allocator.
* @param __args Arguments for the @a _Tp object's constructor.
* @return A shared_ptr that owns the newly created object.
* @throw An exception thrown from @a _Alloc::allocate or from the
* constructor of @a _Tp.
*
* A copy of @a __a will be used to allocate memory for the shared_ptr
* and the new object.
*/
template<typename _Tp, typename _Alloc, typename... _Args>
inline shared_ptr<_Tp>
allocate_shared(const _Alloc& __a, _Args&&... __args)
{
return shared_ptr<_Tp>(_Sp_make_shared_tag(), __a,
std::forward<_Args>(__args)...);
}
/**
* @brief Create an object that is owned by a shared_ptr.
* @param __args Arguments for the @a _Tp object's constructor.
* @return A shared_ptr that owns the newly created object.
* @throw std::bad_alloc, or an exception thrown from the
* constructor of @a _Tp.
*/
template<typename _Tp, typename... _Args>
inline shared_ptr<_Tp>
make_shared(_Args&&... __args)
{
typedef typename std::remove_const<_Tp>::type _Tp_nc;
return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
std::forward<_Args>(__args)...);
}
/// std::hash specialization for shared_ptr.
template<typename _Tp>
struct hash<shared_ptr<_Tp>>
: public __hash_base<size_t, shared_ptr<_Tp>>
{
size_t
operator()(const shared_ptr<_Tp>& __s) const noexcept
{
return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get());
}
};
// @} group pointer_abstractions
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // _SHARED_PTR_H
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