shared_ptr_base.h
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// shared_ptr and weak_ptr implementation details -*- C++ -*-
// Copyright (C) 2007-2013 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
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#if _GLIBCXX_USE_DEPRECATED
template<typename> class auto_ptr;
#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&) = 0;
void
_M_add_ref_copy()
{ __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }
void
_M_add_ref_lock();
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)
{
_GLIBCXX_READ_MEM_BARRIER;
_GLIBCXX_WRITE_MEM_BARRIER;
}
// 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()
_GLIBCXX_READ_MEM_BARRIER;
_GLIBCXX_WRITE_MEM_BARRIER;
}
_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 (__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_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_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));
}
// 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)
: _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&)
{ return 0; }
_Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
_Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;
protected:
_Ptr _M_ptr; // copy constructor must not throw
};
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 { }
// 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>
{
// Helper class that stores the Deleter and also acts as an allocator.
// Used to dispose of the owned pointer and the internal refcount
// Requires that copies of _Alloc can free each other's memory.
struct _My_Deleter
: public _Alloc // copy constructor must not throw
{
_Deleter _M_del; // copy constructor must not throw
_My_Deleter(_Deleter __d, const _Alloc& __a)
: _Alloc(__a), _M_del(__d) { }
};
public:
// __d(__p) must not throw.
_Sp_counted_deleter(_Ptr __p, _Deleter __d)
: _M_ptr(__p), _M_del(__d, _Alloc()) { }
// __d(__p) must not throw.
_Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a)
: _M_ptr(__p), _M_del(__d, __a) { }
~_Sp_counted_deleter() noexcept { }
virtual void
_M_dispose() noexcept
{ _M_del._M_del(_M_ptr); }
virtual void
_M_destroy() noexcept
{
typedef typename allocator_traits<_Alloc>::template
rebind_traits<_Sp_counted_deleter> _Alloc_traits;
typename _Alloc_traits::allocator_type __a(_M_del);
_Alloc_traits::destroy(__a, this);
_Alloc_traits::deallocate(__a, this, 1);
}
virtual void*
_M_get_deleter(const std::type_info& __ti)
{
#ifdef __GXX_RTTI
return __ti == typeid(_Deleter) ? &_M_del._M_del : 0;
#else
return 0;
#endif
}
protected:
_Ptr _M_ptr; // copy constructor must not throw
_My_Deleter _M_del; // copy constructor must not throw
};
// helpers for make_shared / allocate_shared
struct _Sp_make_shared_tag { };
template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
{
// Helper class that stores the pointer and also acts as an allocator.
// Used to dispose of the owned pointer and the internal refcount
// Requires that copies of _Alloc can free each other's memory.
struct _Impl
: public _Alloc // copy constructor must not throw
{
_Impl(_Alloc __a) : _Alloc(__a), _M_ptr() { }
_Tp* _M_ptr;
};
public:
template<typename... _Args>
_Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
: _M_impl(__a), _M_storage()
{
_M_impl._M_ptr = static_cast<_Tp*>(static_cast<void*>(&_M_storage));
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2070. allocate_shared should use allocator_traits<A>::construct
allocator_traits<_Alloc>::construct(__a, _M_impl._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_impl._M_ptr); }
// Override because the allocator needs to know the dynamic type
virtual void
_M_destroy() noexcept
{
typedef typename allocator_traits<_Alloc>::template
rebind_traits<_Sp_counted_ptr_inplace> _Alloc_traits;
typename _Alloc_traits::allocator_type __a(_M_impl);
_Alloc_traits::destroy(__a, this);
_Alloc_traits::deallocate(__a, this, 1);
}
// Sneaky trick so __shared_ptr can get the managed pointer
virtual void*
_M_get_deleter(const std::type_info& __ti) noexcept
{
#ifdef __GXX_RTTI
return __ti == typeid(_Sp_make_shared_tag)
? static_cast<void*>(&_M_storage)
: 0;
#else
return 0;
#endif
}
private:
_Impl _M_impl;
typename aligned_storage<sizeof(_Tp), alignment_of<_Tp>::value>::type
_M_storage;
};
template<_Lock_policy _Lp>
class __shared_count
{
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, typename _Deleter>
__shared_count(_Ptr __p, _Deleter __d) : _M_pi(0)
{
// The allocator's value_type doesn't matter, will rebind it anyway.
typedef std::allocator<int> _Alloc;
typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
typedef typename allocator_traits<_Alloc>::template
rebind_traits<_Sp_cd_type> _Alloc_traits;
typename _Alloc_traits::allocator_type __a;
_Sp_cd_type* __mem = 0;
__try
{
__mem = _Alloc_traits::allocate(__a, 1);
_Alloc_traits::construct(__a, __mem, __p, std::move(__d));
_M_pi = __mem;
}
__catch(...)
{
__d(__p); // Call _Deleter on __p.
if (__mem)
_Alloc_traits::deallocate(__a, __mem, 1);
__throw_exception_again;
}
}
template<typename _Ptr, typename _Deleter, typename _Alloc>
__shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
{
typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
typedef typename allocator_traits<_Alloc>::template
rebind_traits<_Sp_cd_type> _Alloc_traits;
typename _Alloc_traits::allocator_type __a2(__a);
_Sp_cd_type* __mem = 0;
__try
{
__mem = _Alloc_traits::allocate(__a2, 1);
_Alloc_traits::construct(__a2, __mem,
__p, std::move(__d), std::move(__a));
_M_pi = __mem;
}
__catch(...)
{
__d(__p); // Call _Deleter on __p.
if (__mem)
_Alloc_traits::deallocate(__a2, __mem, 1);
__throw_exception_again;
}
}
template<typename _Tp, typename _Alloc, typename... _Args>
__shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a,
_Args&&... __args)
: _M_pi(0)
{
typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
typedef typename allocator_traits<_Alloc>::template
rebind_traits<_Sp_cp_type> _Alloc_traits;
typename _Alloc_traits::allocator_type __a2(__a);
_Sp_cp_type* __mem = _Alloc_traits::allocate(__a2, 1);
__try
{
_Alloc_traits::construct(__a2, __mem, std::move(__a),
std::forward<_Args>(__args)...);
_M_pi = __mem;
}
__catch(...)
{
_Alloc_traits::deallocate(__a2, __mem, 1);
__throw_exception_again;
}
}
#if _GLIBCXX_USE_DEPRECATED
// Special case for auto_ptr<_Tp> to provide the strong guarantee.
template<typename _Tp>
explicit
__shared_count(std::auto_ptr<_Tp>&& __r);
#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(_S_create_from_up(std::move(__r)))
{ __r.release(); }
// Throw bad_weak_ptr when __r._M_get_use_count() == 0.
explicit __shared_count(const __weak_count<_Lp>& __r);
~__shared_count() noexcept
{
if (_M_pi != 0)
_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) : 0; }
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>;
template<typename _Tp, typename _Del>
static _Sp_counted_base<_Lp>*
_S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r,
typename std::enable_if<!std::is_reference<_Del>::value>::type* = 0)
{
typedef typename unique_ptr<_Tp, _Del>::pointer _Ptr;
return new _Sp_counted_deleter<_Ptr, _Del, std::allocator<void>,
_Lp>(__r.get(), __r.get_deleter());
}
template<typename _Tp, typename _Del>
static _Sp_counted_base<_Lp>*
_S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r,
typename std::enable_if<std::is_reference<_Del>::value>::type* = 0)
{
typedef typename unique_ptr<_Tp, _Del>::pointer _Ptr;
typedef typename std::remove_reference<_Del>::type _Del1;
typedef std::reference_wrapper<_Del1> _Del2;
return new _Sp_counted_deleter<_Ptr, _Del2, std::allocator<void>,
_Lp>(__r.get(), std::ref(__r.get_deleter()));
}
_Sp_counted_base<_Lp>* _M_pi;
};
template<_Lock_policy _Lp>
class __weak_count
{
public:
constexpr __weak_count() noexcept : _M_pi(0)
{ }
__weak_count(const __shared_count<_Lp>& __r) noexcept
: _M_pi(__r._M_pi)
{
if (_M_pi != 0)
_M_pi->_M_weak_add_ref();
}
__weak_count(const __weak_count<_Lp>& __r) noexcept
: _M_pi(__r._M_pi)
{
if (_M_pi != 0)
_M_pi->_M_weak_add_ref();
}
~__weak_count() noexcept
{
if (_M_pi != 0)
_M_pi->_M_weak_release();
}
__weak_count<_Lp>&
operator=(const __shared_count<_Lp>& __r) noexcept
{
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != 0)
__tmp->_M_weak_add_ref();
if (_M_pi != 0)
_M_pi->_M_weak_release();
_M_pi = __tmp;
return *this;
}
__weak_count<_Lp>&
operator=(const __weak_count<_Lp>& __r) noexcept
{
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != 0)
__tmp->_M_weak_add_ref();
if (_M_pi != 0)
_M_pi->_M_weak_release();
_M_pi = __tmp;
return *this;
}
void
_M_swap(__weak_count<_Lp>& __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_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 != 0)
_M_pi->_M_add_ref_lock();
else
__throw_bad_weak_ptr();
}
// Support for enable_shared_from_this.
// Friend of __enable_shared_from_this.
template<_Lock_policy _Lp, typename _Tp1, typename _Tp2>
void
__enable_shared_from_this_helper(const __shared_count<_Lp>&,
const __enable_shared_from_this<_Tp1,
_Lp>*, const _Tp2*) noexcept;
// Friend of enable_shared_from_this.
template<typename _Tp1, typename _Tp2>
void
__enable_shared_from_this_helper(const __shared_count<>&,
const enable_shared_from_this<_Tp1>*,
const _Tp2*) noexcept;
template<_Lock_policy _Lp>
inline void
__enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) noexcept
{ }
template<typename _Tp, _Lock_policy _Lp>
class __shared_ptr
{
public:
typedef _Tp element_type;
constexpr __shared_ptr() noexcept
: _M_ptr(0), _M_refcount()
{ }
template<typename _Tp1>
explicit __shared_ptr(_Tp1* __p)
: _M_ptr(__p), _M_refcount(__p)
{
__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
static_assert( sizeof(_Tp1) > 0, "incomplete type" );
__enable_shared_from_this_helper(_M_refcount, __p, __p);
}
template<typename _Tp1, typename _Deleter>
__shared_ptr(_Tp1* __p, _Deleter __d)
: _M_ptr(__p), _M_refcount(__p, __d)
{
__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
// TODO requires _Deleter CopyConstructible and __d(__p) well-formed
__enable_shared_from_this_helper(_M_refcount, __p, __p);
}
template<typename _Tp1, typename _Deleter, typename _Alloc>
__shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a)
: _M_ptr(__p), _M_refcount(__p, __d, std::move(__a))
{
__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
// TODO requires _Deleter CopyConstructible and __d(__p) well-formed
__enable_shared_from_this_helper(_M_refcount, __p, __p);
}
template<typename _Deleter>
__shared_ptr(nullptr_t __p, _Deleter __d)
: _M_ptr(0), _M_refcount(__p, __d)
{ }
template<typename _Deleter, typename _Alloc>
__shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
: _M_ptr(0), _M_refcount(__p, __d, std::move(__a))
{ }
template<typename _Tp1>
__shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __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 _Tp1, typename = typename
std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
__shared_ptr(const __shared_ptr<_Tp1, _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 _Tp1, typename = typename
std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
__shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount()
{
_M_refcount._M_swap(__r._M_refcount);
__r._M_ptr = 0;
}
template<typename _Tp1>
explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
: _M_refcount(__r._M_refcount) // may throw
{
__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
// 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 _Tp1, typename _Del>
__shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r)
: _M_ptr(__r.get()), _M_refcount()
{
__glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>)
auto __tmp = std::__addressof(*__r.get());
_M_refcount = __shared_count<_Lp>(std::move(__r));
__enable_shared_from_this_helper(_M_refcount, __tmp, __tmp);
}
#if _GLIBCXX_USE_DEPRECATED
// Postcondition: use_count() == 1 and __r.get() == 0
template<typename _Tp1>
__shared_ptr(std::auto_ptr<_Tp1>&& __r);
#endif
/* TODO: use delegating constructor */
constexpr __shared_ptr(nullptr_t) noexcept
: _M_ptr(0), _M_refcount()
{ }
template<typename _Tp1>
__shared_ptr&
operator=(const __shared_ptr<_Tp1, _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
template<typename _Tp1>
__shared_ptr&
operator=(std::auto_ptr<_Tp1>&& __r)
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
#endif
__shared_ptr&
operator=(__shared_ptr&& __r) noexcept
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
template<class _Tp1>
__shared_ptr&
operator=(__shared_ptr<_Tp1, _Lp>&& __r) noexcept
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
template<typename _Tp1, typename _Del>
__shared_ptr&
operator=(std::unique_ptr<_Tp1, _Del>&& __r)
{
__shared_ptr(std::move(__r)).swap(*this);
return *this;
}
void
reset() noexcept
{ __shared_ptr().swap(*this); }
template<typename _Tp1>
void
reset(_Tp1* __p) // _Tp1 must be complete.
{
// Catch self-reset errors.
_GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr);
__shared_ptr(__p).swap(*this);
}
template<typename _Tp1, typename _Deleter>
void
reset(_Tp1* __p, _Deleter __d)
{ __shared_ptr(__p, __d).swap(*this); }
template<typename _Tp1, typename _Deleter, typename _Alloc>
void
reset(_Tp1* __p, _Deleter __d, _Alloc __a)
{ __shared_ptr(__p, __d, std::move(__a)).swap(*this); }
// Allow class instantiation when _Tp is [cv-qual] void.
typename std::add_lvalue_reference<_Tp>::type
operator*() const noexcept
{
_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
return *_M_ptr;
}
_Tp*
operator->() const noexcept
{
_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
return _M_ptr;
}
_Tp*
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
{ return _M_refcount._M_less(__rhs._M_refcount); }
template<typename _Tp1>
bool
owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const
{ return _M_refcount._M_less(__rhs._M_refcount); }
#ifdef __GXX_RTTI
protected:
// 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)
: _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a,
std::forward<_Args>(__args)...)
{
// _M_ptr needs to point to the newly constructed object.
// This relies on _Sp_counted_ptr_inplace::_M_get_deleter.
void* __p = _M_refcount._M_get_deleter(typeid(__tag));
_M_ptr = static_cast<_Tp*>(__p);
__enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
}
#else
template<typename _Alloc>
struct _Deleter
{
void operator()(_Tp* __ptr)
{
typedef allocator_traits<_Alloc> _Alloc_traits;
_Alloc_traits::destroy(_M_alloc, __ptr);
_Alloc_traits::deallocate(_M_alloc, __ptr, 1);
}
_Alloc _M_alloc;
};
template<typename _Alloc, typename... _Args>
__shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a,
_Args&&... __args)
: _M_ptr(), _M_refcount()
{
typedef typename _Alloc::template rebind<_Tp>::other _Alloc2;
_Deleter<_Alloc2> __del = { _Alloc2(__a) };
typedef allocator_traits<_Alloc2> __traits;
_M_ptr = __traits::allocate(__del._M_alloc, 1);
__try
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2070. allocate_shared should use allocator_traits<A>::construct
__traits::construct(__del._M_alloc, _M_ptr,
std::forward<_Args>(__args)...);
}
__catch(...)
{
__traits::deallocate(__del._M_alloc, _M_ptr, 1);
__throw_exception_again;
}
__shared_count<_Lp> __count(_M_ptr, __del, __del._M_alloc);
_M_refcount._M_swap(__count);
__enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr);
}
#endif
template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
typename... _Args>
friend __shared_ptr<_Tp1, _Lp1>
__allocate_shared(const _Alloc& __a, _Args&&... __args);
private:
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;
_Tp* _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 _Tp1, typename _Tp2, _Lock_policy _Lp>
inline bool
operator<(const __shared_ptr<_Tp1, _Lp>& __a,
const __shared_ptr<_Tp2, _Lp>& __b) noexcept
{
typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT;
return std::less<_CT>()(__a.get(), __b.get());
}
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{ return std::less<_Tp*>()(__a.get(), nullptr); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return std::less<_Tp*>()(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 std::less<_Tp*>()(nullptr, __a.get()); }
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return std::less<_Tp*>()(__a.get(), 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>>
{ };
// 2.2.3.8 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); }
// 2.2.3.9 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
{ return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__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
{ return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__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
{
if (_Tp* __p = dynamic_cast<_Tp*>(__r.get()))
return __shared_ptr<_Tp, _Lp>(__r, __p);
return __shared_ptr<_Tp, _Lp>();
}
template<typename _Tp, _Lock_policy _Lp>
class __weak_ptr
{
public:
typedef _Tp element_type;
constexpr __weak_ptr() noexcept
: _M_ptr(0), _M_refcount()
{ }
__weak_ptr(const __weak_ptr&) noexcept = default;
__weak_ptr& operator=(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 _Tp1, typename = typename
std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
__weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) noexcept
: _M_refcount(__r._M_refcount)
{ _M_ptr = __r.lock().get(); }
template<typename _Tp1, typename = typename
std::enable_if<std::is_convertible<_Tp1*, _Tp*>::value>::type>
__weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
{ }
template<typename _Tp1>
__weak_ptr&
operator=(const __weak_ptr<_Tp1, _Lp>& __r) noexcept
{
_M_ptr = __r.lock().get();
_M_refcount = __r._M_refcount;
return *this;
}
template<typename _Tp1>
__weak_ptr&
operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
{
_M_ptr = __r._M_ptr;
_M_refcount = __r._M_refcount;
return *this;
}
__shared_ptr<_Tp, _Lp>
lock() const noexcept
{
#ifdef __GTHREADS
// Optimization: avoid throw overhead.
if (expired())
return __shared_ptr<element_type, _Lp>();
__try
{
return __shared_ptr<element_type, _Lp>(*this);
}
__catch(const bad_weak_ptr&)
{
// Q: How can we get here?
// A: Another thread may have invalidated r after the
// use_count test above.
return __shared_ptr<element_type, _Lp>();
}
#else
// Optimization: avoid try/catch overhead when single threaded.
return expired() ? __shared_ptr<element_type, _Lp>()
: __shared_ptr<element_type, _Lp>(*this);
#endif
} // XXX MT
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
{ return _M_refcount._M_less(__rhs._M_refcount); }
template<typename _Tp1>
bool
owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const
{ 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
{
_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>;
_Tp* _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
{ return __lhs.owner_before(__rhs); }
bool
operator()(const _Tp& __lhs, const _Tp1& __rhs) const
{ return __lhs.owner_before(__rhs); }
bool
operator()(const _Tp1& __lhs, const _Tp& __rhs) const
{ return __lhs.owner_before(__rhs); }
};
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); }
private:
template<typename _Tp1>
void
_M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept
{ _M_weak_this._M_assign(__p, __n); }
template<typename _Tp1>
friend void
__enable_shared_from_this_helper(const __shared_count<_Lp>& __pn,
const __enable_shared_from_this* __pe,
const _Tp1* __px) noexcept
{
if (__pe != 0)
__pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn);
}
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)
{
return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __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 std::hash<_Tp*>()(__s.get()); }
};
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // _SHARED_PTR_BASE_H