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// shared_ptr and weak_ptr implementation details -*- C++ -*-
// Copyright (C) 2007-2018 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 bits/shared_ptr_base.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{memory}
*/
#ifndef _SHARED_PTR_BASE_H
#define _SHARED_PTR_BASE_H 1
#include <typeinfo>
#include <bits/allocated_ptr.h>
#include <bits/refwrap.h>
#include <bits/stl_function.h>
#include <ext/aligned_buffer.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#if _GLIBCXX_USE_DEPRECATED
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
template<typename> class auto_ptr;
#pragma GCC diagnostic pop
#endif
/**
* @brief Exception possibly thrown by @c shared_ptr.
* @ingroup exceptions
*/
class bad_weak_ptr : public std::exception
{
public:
virtual char const* what() const noexcept;
virtual ~bad_weak_ptr() noexcept;
};
// Substitute for bad_weak_ptr object in the case of -fno-exceptions.
inline void
__throw_bad_weak_ptr()
{ _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); }
using __gnu_cxx::_Lock_policy;
using __gnu_cxx::__default_lock_policy;
using __gnu_cxx::_S_single;
using __gnu_cxx::_S_mutex;
using __gnu_cxx::_S_atomic;
// Empty helper class except when the template argument is _S_mutex.
template<_Lock_policy _Lp>
class _Mutex_base
{
protected:
// The atomic policy uses fully-fenced builtins, single doesn't care.
enum { _S_need_barriers = 0 };
};
template<>
class _Mutex_base<_S_mutex>
: public __gnu_cxx::__mutex
{
protected:
// This policy is used when atomic builtins are not available.
// The replacement atomic operations might not have the necessary
// memory barriers.
enum { _S_need_barriers = 1 };
};
template<_Lock_policy _Lp = __default_lock_policy>
class _Sp_counted_base
: public _Mutex_base<_Lp>
{
public:
_Sp_counted_base() noexcept
: _M_use_count(1), _M_weak_count(1) { }
virtual
~_Sp_counted_base() noexcept
{ }
// Called when _M_use_count drops to zero, to release the resources
// managed by *this.
virtual void
_M_dispose() noexcept = 0;
// Called when _M_weak_count drops to zero.
virtual void
_M_destroy() noexcept
{ delete this; }
virtual void*
_M_get_deleter(const std::type_info&) noexcept = 0;
void
_M_add_ref_copy()
{ __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
void
_M_add_ref_lock();
bool
_M_add_ref_lock_nothrow();
void
_M_release() noexcept
{
// Be race-detector-friendly. For more info see bits/c++config.
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
{
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
_M_dispose();
// There must be a memory barrier between dispose() and destroy()
// to ensure that the effects of dispose() are observed in the
// thread that runs destroy().
// See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
if (_Mutex_base<_Lp>::_S_need_barriers)
{
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
// Be race-detector-friendly. For more info see bits/c++config.
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
-1) == 1)
{
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
_M_destroy();
}
}
}
void
_M_weak_add_ref() noexcept
{ __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }
void
_M_weak_release() noexcept
{
// Be race-detector-friendly. For more info see bits/c++config.
_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
{
_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
if (_Mutex_base<_Lp>::_S_need_barriers)
{
// See _M_release(),
// destroy() must observe results of dispose()
__atomic_thread_fence (__ATOMIC_ACQ_REL);
}
_M_destroy();
}
}
long
_M_get_use_count() const noexcept
{
// No memory barrier is used here so there is no synchronization
// with other threads.
return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED);
}
private:
_Sp_counted_base(_Sp_counted_base const&) = delete;
_Sp_counted_base& operator=(_Sp_counted_base const&) = delete;
_Atomic_word _M_use_count; // #shared
_Atomic_word _M_weak_count; // #weak + (#shared != 0)
};
template<>
inline void
_Sp_counted_base<_S_single>::
_M_add_ref_lock()
{
if (_M_use_count == 0)
__throw_bad_weak_ptr();
++_M_use_count;
}
template<>
inline void
_Sp_counted_base<_S_mutex>::
_M_add_ref_lock()
{
__gnu_cxx::__scoped_lock sentry(*this);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
{
_M_use_count = 0;
__throw_bad_weak_ptr();
}
}
template<>
inline void
_Sp_counted_base<_S_atomic>::
_M_add_ref_lock()
{
// Perform lock-free add-if-not-zero operation.
_Atomic_word __count = _M_get_use_count();
do
{
if (__count == 0)
__throw_bad_weak_ptr();
// Replace the current counter value with the old value + 1, as
// long as it's not changed meanwhile.
}
while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
true, __ATOMIC_ACQ_REL,
__ATOMIC_RELAXED));
}
template<>
inline bool
_Sp_counted_base<_S_single>::
_M_add_ref_lock_nothrow()
{
if (_M_use_count == 0)
return false;
++_M_use_count;
return true;
}
template<>
inline bool
_Sp_counted_base<_S_mutex>::
_M_add_ref_lock_nothrow()
{
__gnu_cxx::__scoped_lock sentry(*this);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
{
_M_use_count = 0;
return false;
}
return true;
}
template<>
inline bool
_Sp_counted_base<_S_atomic>::
_M_add_ref_lock_nothrow()
{
// Perform lock-free add-if-not-zero operation.
_Atomic_word __count = _M_get_use_count();
do
{
if (__count == 0)
return false;
// Replace the current counter value with the old value + 1, as
// long as it's not changed meanwhile.
}
while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
true, __ATOMIC_ACQ_REL,
__ATOMIC_RELAXED));
return true;
}
template<>
inline void
_Sp_counted_base<_S_single>::_M_add_ref_copy()
{ ++_M_use_count; }
template<>
inline void
_Sp_counted_base<_S_single>::_M_release() noexcept
{
if (--_M_use_count == 0)
{
_M_dispose();
if (--_M_weak_count == 0)
_M_destroy();
}
}
template<>
inline void
_Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept
{ ++_M_weak_count; }
template<>
inline void
_Sp_counted_base<_S_single>::_M_weak_release() noexcept
{
if (--_M_weak_count == 0)
_M_destroy();
}
template<>
inline long
_Sp_counted_base<_S_single>::_M_get_use_count() const noexcept
{ return _M_use_count; }
// Forward declarations.
template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
class __shared_ptr;
template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
class __weak_ptr;
template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
class __enable_shared_from_this;
template<typename _Tp>
class shared_ptr;
template<typename _Tp>
class weak_ptr;
template<typename _Tp>
struct owner_less;
template<typename _Tp>
class enable_shared_from_this;
template<_Lock_policy _Lp = __default_lock_policy>
class __weak_count;
template<_Lock_policy _Lp = __default_lock_policy>
class __shared_count;
// Counted ptr with no deleter or allocator support
template<typename _Ptr, _Lock_policy _Lp>
class _Sp_counted_ptr final : public _Sp_counted_base<_Lp>
{
public:
explicit
_Sp_counted_ptr(_Ptr __p) noexcept
: _M_ptr(__p) { }
virtual void
_M_dispose() noexcept
{ delete _M_ptr; }
virtual void
_M_destroy() noexcept
{ delete this; }
virtual void*
_M_get_deleter(const std::type_info&) noexcept
{ return nullptr; }
_Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
_Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
private:
_Ptr _M_ptr;
};
template<>
inline void
_Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { }
template<>
inline void
_Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { }
template<>
inline void
_Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { }
template<int _Nm, typename _Tp,
bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
struct _Sp_ebo_helper;
/// Specialization using EBO.
template<int _Nm, typename _Tp>
struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp
{
explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { }
explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { }
static _Tp&
_S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); }
};
/// Specialization not using EBO.
template<int _Nm, typename _Tp>
struct _Sp_ebo_helper<_Nm, _Tp, false>
{
explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { }
explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { }
static _Tp&
_S_get(_Sp_ebo_helper& __eboh)
{ return __eboh._M_tp; }
private:
_Tp _M_tp;
};
// Support for custom deleter and/or allocator
template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
class _Sp_counted_deleter final : public _Sp_counted_base<_Lp>
{
class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc>
{
typedef _Sp_ebo_helper<0, _Deleter> _Del_base;
typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base;
public:
_Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
: _M_ptr(__p), _Del_base(std::move(__d)), _Alloc_base(__a)
{ }
_Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); }
_Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); }
_Ptr _M_ptr;
};
public:
using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>;
// __d(__p) must not throw.
_Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept
: _M_impl(__p, std::move(__d), _Alloc()) { }
// __d(__p) must not throw.
_Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
: _M_impl(__p, std::move(__d), __a) { }
~_Sp_counted_deleter() noexcept { }
virtual void
_M_dispose() noexcept
{ _M_impl._M_del()(_M_impl._M_ptr); }
virtual void
_M_destroy() noexcept
{
__allocator_type __a(_M_impl._M_alloc());
__allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
this->~_Sp_counted_deleter();
}
virtual void*
_M_get_deleter(const std::type_info& __ti) noexcept
{
#if __cpp_rtti
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2400. shared_ptr's get_deleter() should use addressof()
return __ti == typeid(_Deleter)
? std::__addressof(_M_impl._M_del())
: nullptr;
#else
return nullptr;
#endif
}
private:
_Impl _M_impl;
};
// helpers for make_shared / allocate_shared
struct _Sp_make_shared_tag
{
private:
template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
friend class _Sp_counted_ptr_inplace;
static const type_info&
_S_ti() noexcept _GLIBCXX_VISIBILITY(default)
{
alignas(type_info) static constexpr char __tag[sizeof(type_info)] = { };
return reinterpret_cast<const type_info&>(__tag);
}
};
template<typename _Alloc>
struct _Sp_alloc_shared_tag
{
const _Alloc& _M_a;
};
template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
{
class _Impl : _Sp_ebo_helper<0, _Alloc>
{
typedef _Sp_ebo_helper<0, _Alloc> _A_base;
public:
explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { }
_Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); }
__gnu_cxx::__aligned_buffer<_Tp> _M_storage;
};
public:
using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>;
template<typename... _Args>
_Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
: _M_impl(__a)
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2070. allocate_shared should use allocator_traits<A>::construct
allocator_traits<_Alloc>::construct(__a, _M_ptr(),
std::forward<_Args>(__args)...); // might throw
}
~_Sp_counted_ptr_inplace() noexcept { }
virtual void
_M_dispose() noexcept
{
allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr());
}
// Override because the allocator needs to know the dynamic type
virtual void
_M_destroy() noexcept
{
__allocator_type __a(_M_impl._M_alloc());
__allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
this->~_Sp_counted_ptr_inplace();
}
private:
friend class __shared_count<_Lp>; // To be able to call _M_ptr().
// No longer used, but code compiled against old libstdc++ headers
// might still call it from __shared_ptr ctor to get the pointer out.
virtual void*
_M_get_deleter(const std::type_info& __ti) noexcept override
{
// Check for the fake type_info first, so we don't try to access it
// as a real type_info object.
if (&__ti == &_Sp_make_shared_tag::_S_ti())
return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
#if __cpp_rtti
// Callers compiled with old libstdc++ headers and RTTI enabled
// might pass this instead:
else if (__ti == typeid(_Sp_make_shared_tag))
return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
#else
// Cannot detect a real type_info object. If the linker keeps a
// definition of this function compiled with -fno-rtti then callers
// that have RTTI enabled and pass a real type_info object will get
// a null pointer returned.
#endif
return nullptr;
}
_Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); }
_Impl _M_impl;
};
// The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>.
struct __sp_array_delete
{
template<typename _Yp>
void operator()(_Yp* __p) const { delete[] __p; }
};
template<_Lock_policy _Lp>
class __shared_count
{
template<typename _Tp>
struct __not_alloc_shared_tag { using type = void; };
template<typename _Tp>
struct __not_alloc_shared_tag<_Sp_alloc_shared_tag<_Tp>> { };
public:
constexpr __shared_count() noexcept : _M_pi(0)
{ }
template<typename _Ptr>
explicit
__shared_count(_Ptr __p) : _M_pi(0)
{
__try
{
_M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
}
__catch(...)
{
delete __p;
__throw_exception_again;
}
}
template<typename _Ptr>
__shared_count(_Ptr __p, /* is_array = */ false_type)
: __shared_count(__p)
{ }
template<typename _Ptr>
__shared_count(_Ptr __p, /* is_array = */ true_type)
: __shared_count(__p, __sp_array_delete{}, allocator<void>())
{ }
template<typename _Ptr, typename _Deleter,
typename = typename __not_alloc_shared_tag<_Deleter>::type>
__shared_count(_Ptr __p, _Deleter __d)
: __shared_count(__p, std::move(__d), allocator<void>())
{ }
template<typename _Ptr, typename _Deleter, typename _Alloc,
typename = typename __not_alloc_shared_tag<_Deleter>::type>
__shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
{
typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
__try
{
typename _Sp_cd_type::__allocator_type __a2(__a);
auto __guard = std::__allocate_guarded(__a2);
_Sp_cd_type* __mem = __guard.get();
::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a));
_M_pi = __mem;
__guard = nullptr;
}
__catch(...)
{
__d(__p); // Call _Deleter on __p.
__throw_exception_again;
}
}
template<typename _Tp, typename _Alloc, typename... _Args>
__shared_count(_Tp*& __p, _Sp_alloc_shared_tag<_Alloc> __a,
_Args&&... __args)
{
typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
typename _Sp_cp_type::__allocator_type __a2(__a._M_a);
auto __guard = std::__allocate_guarded(__a2);
_Sp_cp_type* __mem = __guard.get();
auto __pi = ::new (__mem)
_Sp_cp_type(__a._M_a, std::forward<_Args>(__args)...);
__guard = nullptr;
_M_pi = __pi;
__p = __pi->_M_ptr();
}
#if _GLIBCXX_USE_DEPRECATED
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
// Special case for auto_ptr<_Tp> to provide the strong guarantee.
template<typename _Tp>
explicit
__shared_count(std::auto_ptr<_Tp>&& __r);
#pragma GCC diagnostic pop
#endif
// Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
template<typename _Tp, typename _Del>
explicit
__shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0)
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2415. Inconsistency between unique_ptr and shared_ptr
if (__r.get() == nullptr)
return;
using _Ptr = typename unique_ptr<_Tp, _Del>::pointer;
using _Del2 = typename conditional<is_reference<_Del>::value,
reference_wrapper<typename remove_reference<_Del>::type>,
_Del>::type;
using _Sp_cd_type
= _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>;
using _Alloc = allocator<_Sp_cd_type>;
using _Alloc_traits = allocator_traits<_Alloc>;
_Alloc __a;
_Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1);
_Alloc_traits::construct(__a, __mem, __r.release(),
__r.get_deleter()); // non-throwing
_M_pi = __mem;
}
// Throw bad_weak_ptr when __r._M_get_use_count() == 0.
explicit __shared_count(const __weak_count<_Lp>& __r);
// Does not throw if __r._M_get_use_count() == 0, caller must check.
explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t);
~__shared_count() noexcept
{
if (_M_pi != nullptr)
_M_pi->_M_release();
}
__shared_count(const __shared_count& __r) noexcept
: _M_pi(__r._M_pi)
{
if (_M_pi != 0)
_M_pi->_M_add_ref_copy();
}
__shared_count&
operator=(const __shared_count& __r) noexcept
{
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != _M_pi)
{
if (__tmp != 0)
__tmp->_M_add_ref_copy();
if (_M_pi != 0)
_M_pi->_M_release();
_M_pi = __tmp;
}
return *this;
}
void
_M_swap(__shared_count& __r) noexcept
{
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
__r._M_pi = _M_pi;
_M_pi = __tmp;
}
long
_M_get_use_count() const noexcept
{ return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }
bool
_M_unique() const noexcept
{ return this->_M_get_use_count() == 1; }
void*
_M_get_deleter(const std::type_info& __ti) const noexcept
{ return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; }
bool
_M_less(const __shared_count& __rhs) const noexcept
{ return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
bool
_M_less(const __weak_count<_Lp>& __rhs) const noexcept
{ return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
// Friend function injected into enclosing namespace and found by ADL
friend inline bool
operator==(const __shared_count& __a, const __shared_count& __b) noexcept
{ return __a._M_pi == __b._M_pi; }
private:
friend class __weak_count<_Lp>;
_Sp_counted_base<_Lp>* _M_pi;
};
template<_Lock_policy _Lp>
class __weak_count
{
public:
constexpr __weak_count() noexcept : _M_pi(nullptr)
{ }
__weak_count(const __shared_count<_Lp>& __r) noexcept
: _M_pi(__r._M_pi)
{
if (_M_pi != nullptr)
_M_pi->_M_weak_add_ref();
}
__weak_count(const __weak_count& __r) noexcept
: _M_pi(__r._M_pi)
{
if (_M_pi != nullptr)
_M_pi->_M_weak_add_ref();
}
__weak_count(__weak_count&& __r) noexcept
: _M_pi(__r._M_pi)
{ __r._M_pi = nullptr; }
~__weak_count() noexcept
{
if (_M_pi != nullptr)
_M_pi->_M_weak_release();
}
__weak_count&
operator=(const __shared_count<_Lp>& __r) noexcept
{
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != nullptr)
__tmp->_M_weak_add_ref();
if (_M_pi != nullptr)
_M_pi->_M_weak_release();
_M_pi = __tmp;
return *this;
}
__weak_count&
operator=(const __weak_count& __r) noexcept
{
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != nullptr)
__tmp->_M_weak_add_ref();
if (_M_pi != nullptr)
_M_pi->_M_weak_release();
_M_pi = __tmp;
return *this;
}
__weak_count&
operator=(__weak_count&& __r) noexcept
{
if (_M_pi != nullptr)
_M_pi->_M_weak_release();
_M_pi = __r._M_pi;
__r._M_pi = nullptr;
return *this;
}
void
_M_swap(__weak_count& __r) noexcept
{
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
__r._M_pi = _M_pi;
_M_pi = __tmp;
}
long
_M_get_use_count() const noexcept
{ return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; }
bool
_M_less(const __weak_count& __rhs) const noexcept
{ return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
bool
_M_less(const __shared_count<_Lp>& __rhs) const noexcept
{ return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }
// Friend function injected into enclosing namespace and found by ADL
friend inline bool
operator==(const __weak_count& __a, const __weak_count& __b) noexcept
{ return __a._M_pi == __b._M_pi; }
private:
friend class __shared_count<_Lp>;
_Sp_counted_base<_Lp>* _M_pi;
};
// Now that __weak_count is defined we can define this constructor:
template<_Lock_policy _Lp>
inline
__shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r)
: _M_pi(__r._M_pi)
{
if (_M_pi != nullptr)
_M_pi->_M_add_ref_lock();
else
__throw_bad_weak_ptr();
}
// Now that __weak_count is defined we can define this constructor:
template<_Lock_policy _Lp>
inline
__shared_count<_Lp>::
__shared_count(const __weak_count<_Lp>& __r, std::nothrow_t)
: _M_pi(__r._M_pi)
{
if (_M_pi != nullptr)
if (!_M_pi->_M_add_ref_lock_nothrow())
_M_pi = nullptr;
}
#define __cpp_lib_shared_ptr_arrays 201603
// Helper traits for shared_ptr of array:
// A pointer type Y* is said to be compatible with a pointer type T* when
// either Y* is convertible to T* or Y is U[N] and T is U cv [].
template<typename _Yp_ptr, typename _Tp_ptr>
struct __sp_compatible_with
: false_type
{ };
template<typename _Yp, typename _Tp>
struct __sp_compatible_with<_Yp*, _Tp*>
: is_convertible<_Yp*, _Tp*>::type
{ };
template<typename _Up, size_t _Nm>
struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]>
: true_type
{ };
template<typename _Up, size_t _Nm>
struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]>
: true_type
{ };
template<typename _Up, size_t _Nm>
struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]>
: true_type
{ };
template<typename _Up, size_t _Nm>
struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]>
: true_type
{ };
// Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N].
template<typename _Up, size_t _Nm, typename _Yp, typename = void>
struct __sp_is_constructible_arrN
: false_type
{ };
template<typename _Up, size_t _Nm, typename _Yp>
struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>>
: is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type
{ };
// Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[].
template<typename _Up, typename _Yp, typename = void>
struct __sp_is_constructible_arr
: false_type
{ };
template<typename _Up, typename _Yp>
struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>>
: is_convertible<_Yp(*)[], _Up(*)[]>::type
{ };
// Trait to check if shared_ptr<T> can be constructed from Y*.
template<typename _Tp, typename _Yp>
struct __sp_is_constructible;
// When T is U[N], Y(*)[N] shall be convertible to T*;
template<typename _Up, size_t _Nm, typename _Yp>
struct __sp_is_constructible<_Up[_Nm], _Yp>
: __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type
{ };
// when T is U[], Y(*)[] shall be convertible to T*;
template<typename _Up, typename _Yp>
struct __sp_is_constructible<_Up[], _Yp>
: __sp_is_constructible_arr<_Up, _Yp>::type
{ };
// otherwise, Y* shall be convertible to T*.
template<typename _Tp, typename _Yp>
struct __sp_is_constructible
: is_convertible<_Yp*, _Tp*>::type
{ };
// Define operator* and operator-> for shared_ptr<T>.
template<typename _Tp, _Lock_policy _Lp,
bool = is_array<_Tp>::value, bool = is_void<_Tp>::value>
class __shared_ptr_access
{
public:
using element_type = _Tp;
element_type&
operator*() const noexcept
{
__glibcxx_assert(_M_get() != nullptr);
return *_M_get();
}
element_type*
operator->() const noexcept
{
_GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
return _M_get();
}
private:
element_type*
_M_get() const noexcept
{ return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
};
// Define operator-> for shared_ptr<cv void>.
template<typename _Tp, _Lock_policy _Lp>
class __shared_ptr_access<_Tp, _Lp, false, true>
{
public:
using element_type = _Tp;
element_type*
operator->() const noexcept
{
auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get();
_GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr);
return __ptr;
}
};
// Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>.
template<typename _Tp, _Lock_policy _Lp>
class __shared_ptr_access<_Tp, _Lp, true, false>
{
public:
using element_type = typename remove_extent<_Tp>::type;
#if __cplusplus <= 201402L
[[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]]
element_type&
operator*() const noexcept
{
__glibcxx_assert(_M_get() != nullptr);
return *_M_get();
}
[[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]]
element_type*
operator->() const noexcept
{
_GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
return _M_get();
}
#endif
element_type&
operator[](ptrdiff_t __i) const
{
__glibcxx_assert(_M_get() != nullptr);
__glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value);
return _M_get()[__i];
}
private:
element_type*
_M_get() const noexcept
{ return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
};
template<typename _Tp, _Lock_policy _Lp>
class __shared_ptr
: public __shared_ptr_access<_Tp, _Lp>
{
public:
using element_type = typename remove_extent<_Tp>::type;
private:
// Constraint for taking ownership of a pointer of type _Yp*:
template<typename _Yp>
using _SafeConv
= typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type;
// Constraint for construction from shared_ptr and weak_ptr:
template<typename _Yp, typename _Res = void>
using _Compatible = typename
enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
// Constraint for assignment from shared_ptr and weak_ptr:
template<typename _Yp>
using _Assignable = _Compatible<_Yp, __shared_ptr&>;
// Constraint for construction from unique_ptr:
template<typename _Yp, typename _Del, typename _Res = void,
typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer>
using _UniqCompatible = typename enable_if<__and_<
__sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*>
>::value, _Res>::type;
// Constraint for assignment from unique_ptr:
template<typename _Yp, typename _Del>
using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>;
public:
#if __cplusplus > 201402L
using weak_type = __weak_ptr<_Tp, _Lp>;
#endif
constexpr __shared_ptr() noexcept
: _M_ptr(0), _M_refcount()
{ }
template<typename _Yp, typename = _SafeConv<_Yp>>
explicit
__shared_ptr(_Yp* __p)
: _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type())
{
static_assert( !is_void<_Yp>::value, "incomplete type" );
static_assert( sizeof(_Yp) > 0, "incomplete type" );
_M_enable_shared_from_this_with(__p);
}
template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>>
__shared_ptr(_Yp* __p, _Deleter __d)
: _M_ptr(__p), _M_refcount(__p, std::move(__d))
{
static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
"deleter expression d(p) is well-formed");
_M_enable_shared_from_this_with(__p);
}
template<typename _Yp, typename _Deleter, typename _Alloc,
typename = _SafeConv<_Yp>>
__shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
: _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a))
{
static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
"deleter expression d(p) is well-formed");
_M_enable_shared_from_this_with(__p);
}
template<typename _Deleter>
__shared_ptr(nullptr_t __p, _Deleter __d)
: _M_ptr(0), _M_refcount(__p, std::move(__d))
{ }
template<typename _Deleter, typename _Alloc>
__shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
: _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a))
{ }
template<typename _Yp>
__shared_ptr(const __shared_ptr<_Yp, _Lp>& __r,
element_type* __p) noexcept
: _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
{ }
__shared_ptr(const __shared_ptr&) noexcept = default;
__shared_ptr& operator=(const __shared_ptr&) noexcept = default;
~__shared_ptr() = default;
template<typename _Yp, typename = _Compatible<_Yp>>
__shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
{ }
__shared_ptr(__shared_ptr&& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount()
{
_M_refcount._M_swap(__r._M_refcount);
__r._M_ptr = 0;
}
template<typename _Yp, typename = _Compatible<_Yp>>
__shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount()
{
_M_refcount._M_swap(__r._M_refcount);
__r._M_ptr = 0;
}
template<typename _Yp, typename = _Compatible<_Yp>>
explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r)
: _M_refcount(__r._M_refcount) // may throw
{
// It is now safe to copy __r._M_ptr, as
// _M_refcount(__r._M_refcount) did not throw.
_M_ptr = __r._M_ptr;
}
// If an exception is thrown this constructor has no effect.
template<typename _Yp, typename _Del,
typename = _UniqCompatible<_Yp, _Del>>
__shared_ptr(unique_ptr<_Yp, _Del>&& __r)
: _M_ptr(__r.get()), _M_refcount()
{
auto __raw = __to_address(__r.get());
_M_refcount = __shared_count<_Lp>(std::move(__r));
_M_enable_shared_from_this_with(__raw);
}
#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATED
protected:
// If an exception is thrown this constructor has no effect.
template<typename _Tp1, typename _Del,
typename enable_if<__and_<
__not_<is_array<_Tp>>, is_array<_Tp1>,
is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*>
>::value, bool>::type = true>
__shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete)
: _M_ptr(__r.get()), _M_refcount()
{
auto __raw = __to_address(__r.get());
_M_refcount = __shared_count<_Lp>(std::move(__r));
_M_enable_shared_from_this_with(__raw);
}
public:
#endif
#if _GLIBCXX_USE_DEPRECATED
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
// Postcondition: use_count() == 1 and __r.get() == 0
template<typename _Yp, typename = _Compatible<_Yp>>
__shared_ptr(auto_ptr<_Yp>&& __r);
#pragma GCC diagnostic pop
#endif
constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { }
template<typename _Yp>
_Assignable<_Yp>
operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
{
_M_ptr = __r._M_ptr;
_M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
return *this;
}
#if _GLIBCXX_USE_DEPRECATED
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
template<typename _Yp>
_Assignable<_Yp>
operator=(auto_ptr<_Yp>&& __r)
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
#pragma GCC diagnostic pop
#endif
__shared_ptr&
operator=(__shared_ptr&& __r) noexcept
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
template<class _Yp>
_Assignable<_Yp>
operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
template<typename _Yp, typename _Del>
_UniqAssignable<_Yp, _Del>
operator=(unique_ptr<_Yp, _Del>&& __r)
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
void
reset() noexcept
{ __shared_ptr().swap(*this); }
template<typename _Yp>
_SafeConv<_Yp>
reset(_Yp* __p) // _Yp must be complete.
{
// Catch self-reset errors.
__glibcxx_assert(__p == 0 || __p != _M_ptr);
__shared_ptr(__p).swap(*this);
}
template<typename _Yp, typename _Deleter>
_SafeConv<_Yp>
reset(_Yp* __p, _Deleter __d)
{ __shared_ptr(__p, std::move(__d)).swap(*this); }
template<typename _Yp, typename _Deleter, typename _Alloc>
_SafeConv<_Yp>
reset(_Yp* __p, _Deleter __d, _Alloc __a)
{ __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); }
element_type*
get() const noexcept
{ return _M_ptr; }
explicit operator bool() const // never throws
{ return _M_ptr == 0 ? false : true; }
bool
unique() const noexcept
{ return _M_refcount._M_unique(); }
long
use_count() const noexcept
{ return _M_refcount._M_get_use_count(); }
void
swap(__shared_ptr<_Tp, _Lp>& __other) noexcept
{
std::swap(_M_ptr, __other._M_ptr);
_M_refcount._M_swap(__other._M_refcount);
}
template<typename _Tp1>
bool
owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }
template<typename _Tp1>
bool
owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }
protected:
// This constructor is non-standard, it is used by allocate_shared.
template<typename _Alloc, typename... _Args>
__shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
: _M_ptr(), _M_refcount(_M_ptr, __tag, std::forward<_Args>(__args)...)
{ _M_enable_shared_from_this_with(_M_ptr); }
template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
typename... _Args>
friend __shared_ptr<_Tp1, _Lp1>
__allocate_shared(const _Alloc& __a, _Args&&... __args);
// This constructor is used by __weak_ptr::lock() and
// shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).
__shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t)
: _M_refcount(__r._M_refcount, std::nothrow)
{
_M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;
}
friend class __weak_ptr<_Tp, _Lp>;
private:
template<typename _Yp>
using __esft_base_t = decltype(__enable_shared_from_this_base(
std::declval<const __shared_count<_Lp>&>(),
std::declval<_Yp*>()));
// Detect an accessible and unambiguous enable_shared_from_this base.
template<typename _Yp, typename = void>
struct __has_esft_base
: false_type { };
template<typename _Yp>
struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>>
: __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays
template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
typename enable_if<__has_esft_base<_Yp2>::value>::type
_M_enable_shared_from_this_with(_Yp* __p) noexcept
{
if (auto __base = __enable_shared_from_this_base(_M_refcount, __p))
__base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount);
}
template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
typename enable_if<!__has_esft_base<_Yp2>::value>::type
_M_enable_shared_from_this_with(_Yp*) noexcept
{ }
void*
_M_get_deleter(const std::type_info& __ti) const noexcept
{ return _M_refcount._M_get_deleter(__ti); }
template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept;
template<typename _Del, typename _Tp1>
friend _Del* get_deleter(const shared_ptr<_Tp1>&) noexcept;
element_type* _M_ptr; // Contained pointer.
__shared_count<_Lp> _M_refcount; // Reference counter.
};
// 20.7.2.2.7 shared_ptr comparisons
template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
inline bool
operator==(const __shared_ptr<_Tp1, _Lp>& __a,
const __shared_ptr<_Tp2, _Lp>& __b) noexcept
{ return __a.get() == __b.get(); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{ return !__a; }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return !__a; }
template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
inline bool
operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
const __shared_ptr<_Tp2, _Lp>& __b) noexcept
{ return __a.get() != __b.get(); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{ return (bool)__a; }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return (bool)__a; }
template<typename _Tp, typename _Up, _Lock_policy _Lp>
inline bool
operator<(const __shared_ptr<_Tp, _Lp>& __a,
const __shared_ptr<_Up, _Lp>& __b) noexcept
{
using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type;
using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
return less<_Vp>()(__a.get(), __b.get());
}
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{
using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
return less<_Tp_elt*>()(__a.get(), nullptr);
}
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{
using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
return less<_Tp_elt*>()(nullptr, __a.get());
}
template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
inline bool
operator<=(const __shared_ptr<_Tp1, _Lp>& __a,
const __shared_ptr<_Tp2, _Lp>& __b) noexcept
{ return !(__b < __a); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{ return !(nullptr < __a); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return !(__a < nullptr); }
template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
inline bool
operator>(const __shared_ptr<_Tp1, _Lp>& __a,
const __shared_ptr<_Tp2, _Lp>& __b) noexcept
{ return (__b < __a); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{ return nullptr < __a; }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return __a < nullptr; }
template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
inline bool
operator>=(const __shared_ptr<_Tp1, _Lp>& __a,
const __shared_ptr<_Tp2, _Lp>& __b) noexcept
{ return !(__a < __b); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{ return !(__a < nullptr); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return !(nullptr < __a); }
template<typename _Sp>
struct _Sp_less : public binary_function<_Sp, _Sp, bool>
{
bool
operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept
{
typedef typename _Sp::element_type element_type;
return std::less<element_type*>()(__lhs.get(), __rhs.get());
}
};
template<typename _Tp, _Lock_policy _Lp>
struct less<__shared_ptr<_Tp, _Lp>>
: public _Sp_less<__shared_ptr<_Tp, _Lp>>
{ };
// 20.7.2.2.8 shared_ptr specialized algorithms.
template<typename _Tp, _Lock_policy _Lp>
inline void
swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept
{ __a.swap(__b); }
// 20.7.2.2.9 shared_ptr casts
// The seemingly equivalent code:
// shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
// will eventually result in undefined behaviour, attempting to
// delete the same object twice.
/// static_pointer_cast
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
inline __shared_ptr<_Tp, _Lp>
static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
{
using _Sp = __shared_ptr<_Tp, _Lp>;
return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
}
// The seemingly equivalent code:
// shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
// will eventually result in undefined behaviour, attempting to
// delete the same object twice.
/// const_pointer_cast
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
inline __shared_ptr<_Tp, _Lp>
const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
{
using _Sp = __shared_ptr<_Tp, _Lp>;
return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
}
// The seemingly equivalent code:
// shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
// will eventually result in undefined behaviour, attempting to
// delete the same object twice.
/// dynamic_pointer_cast
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
inline __shared_ptr<_Tp, _Lp>
dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
{
using _Sp = __shared_ptr<_Tp, _Lp>;
if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
return _Sp(__r, __p);
return _Sp();
}
#if __cplusplus > 201402L
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
inline __shared_ptr<_Tp, _Lp>
reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
{
using _Sp = __shared_ptr<_Tp, _Lp>;
return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
}
#endif
template<typename _Tp, _Lock_policy _Lp>
class __weak_ptr
{
template<typename _Yp, typename _Res = void>
using _Compatible = typename
enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;
// Constraint for assignment from shared_ptr and weak_ptr:
template<typename _Yp>
using _Assignable = _Compatible<_Yp, __weak_ptr&>;
public:
using element_type = typename remove_extent<_Tp>::type;
constexpr __weak_ptr() noexcept
: _M_ptr(nullptr), _M_refcount()
{ }
__weak_ptr(const __weak_ptr&) noexcept = default;
~__weak_ptr() = default;
// The "obvious" converting constructor implementation:
//
// template<typename _Tp1>
// __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
// : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
// { }
//
// has a serious problem.
//
// __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
// conversion may require access to *__r._M_ptr (virtual inheritance).
//
// It is not possible to avoid spurious access violations since
// in multithreaded programs __r._M_ptr may be invalidated at any point.
template<typename _Yp, typename = _Compatible<_Yp>>
__weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept
: _M_refcount(__r._M_refcount)
{ _M_ptr = __r.lock().get(); }
template<typename _Yp, typename = _Compatible<_Yp>>
__weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
{ }
__weak_ptr(__weak_ptr&& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount))
{ __r._M_ptr = nullptr; }
template<typename _Yp, typename = _Compatible<_Yp>>
__weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept
: _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount))
{ __r._M_ptr = nullptr; }
__weak_ptr&
operator=(const __weak_ptr& __r) noexcept = default;
template<typename _Yp>
_Assignable<_Yp>
operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept
{
_M_ptr = __r.lock().get();
_M_refcount = __r._M_refcount;
return *this;
}
template<typename _Yp>
_Assignable<_Yp>
operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
{
_M_ptr = __r._M_ptr;
_M_refcount = __r._M_refcount;
return *this;
}
__weak_ptr&
operator=(__weak_ptr&& __r) noexcept
{
_M_ptr = __r._M_ptr;
_M_refcount = std::move(__r._M_refcount);
__r._M_ptr = nullptr;
return *this;
}
template<typename _Yp>
_Assignable<_Yp>
operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept
{
_M_ptr = __r.lock().get();
_M_refcount = std::move(__r._M_refcount);
__r._M_ptr = nullptr;
return *this;
}
__shared_ptr<_Tp, _Lp>
lock() const noexcept
{ return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }
long
use_count() const noexcept
{ return _M_refcount._M_get_use_count(); }
bool
expired() const noexcept
{ return _M_refcount._M_get_use_count() == 0; }
template<typename _Tp1>
bool
owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }
template<typename _Tp1>
bool
owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }
void
reset() noexcept
{ __weak_ptr().swap(*this); }
void
swap(__weak_ptr& __s) noexcept
{
std::swap(_M_ptr, __s._M_ptr);
_M_refcount._M_swap(__s._M_refcount);
}
private:
// Used by __enable_shared_from_this.
void
_M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept
{
if (use_count() == 0)
{
_M_ptr = __ptr;
_M_refcount = __refcount;
}
}
template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
friend class __enable_shared_from_this<_Tp, _Lp>;
friend class enable_shared_from_this<_Tp>;
element_type* _M_ptr; // Contained pointer.
__weak_count<_Lp> _M_refcount; // Reference counter.
};
// 20.7.2.3.6 weak_ptr specialized algorithms.
template<typename _Tp, _Lock_policy _Lp>
inline void
swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept
{ __a.swap(__b); }
template<typename _Tp, typename _Tp1>
struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept
{ return __lhs.owner_before(__rhs); }
bool
operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept
{ return __lhs.owner_before(__rhs); }
bool
operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept
{ return __lhs.owner_before(__rhs); }
};
template<>
struct _Sp_owner_less<void, void>
{
template<typename _Tp, typename _Up>
auto
operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept
-> decltype(__lhs.owner_before(__rhs))
{ return __lhs.owner_before(__rhs); }
using is_transparent = void;
};
template<typename _Tp, _Lock_policy _Lp>
struct owner_less<__shared_ptr<_Tp, _Lp>>
: public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
{ };
template<typename _Tp, _Lock_policy _Lp>
struct owner_less<__weak_ptr<_Tp, _Lp>>
: public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
{ };
template<typename _Tp, _Lock_policy _Lp>
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, _Lp>
shared_from_this()
{ return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }
__shared_ptr<const _Tp, _Lp>
shared_from_this() const
{ return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
__weak_ptr<_Tp, _Lp>
weak_from_this() noexcept
{ return this->_M_weak_this; }
__weak_ptr<const _Tp, _Lp>
weak_from_this() const noexcept
{ return this->_M_weak_this; }
#endif
private:
template<typename _Tp1>
void
_M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept
{ _M_weak_this._M_assign(__p, __n); }
friend const __enable_shared_from_this*
__enable_shared_from_this_base(const __shared_count<_Lp>&,
const __enable_shared_from_this* __p)
{ return __p; }
template<typename, _Lock_policy>
friend class __shared_ptr;
mutable __weak_ptr<_Tp, _Lp> _M_weak_this;
};
template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args>
inline __shared_ptr<_Tp, _Lp>
__allocate_shared(const _Alloc& __a, _Args&&... __args)
{
static_assert(!is_array<_Tp>::value, "make_shared<T[]> not supported");
return __shared_ptr<_Tp, _Lp>(_Sp_alloc_shared_tag<_Alloc>{__a},
std::forward<_Args>(__args)...);
}
template<typename _Tp, _Lock_policy _Lp, typename... _Args>
inline __shared_ptr<_Tp, _Lp>
__make_shared(_Args&&... __args)
{
typedef typename std::remove_const<_Tp>::type _Tp_nc;
return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
std::forward<_Args>(__args)...);
}
/// std::hash specialization for __shared_ptr.
template<typename _Tp, _Lock_policy _Lp>
struct hash<__shared_ptr<_Tp, _Lp>>
: public __hash_base<size_t, __shared_ptr<_Tp, _Lp>>
{
size_t
operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept
{
return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()(
__s.get());
}
};
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // _SHARED_PTR_BASE_H
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