// shared_ptr and weak_ptr implementation details -*- C++ -*- // Copyright (C) 2007, 2008, 2009, 2010, 2011 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 // . // 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 /** * @brief Exception possibly thrown by @c shared_ptr. * @ingroup exceptions */ class bad_weak_ptr : public std::exception { public: virtual char const* what() const throw(); virtual ~bad_weak_ptr() throw(); }; // Substitute for bad_weak_ptr object in the case of -fno-exceptions. inline void __throw_bad_weak_ptr() { #if __EXCEPTIONS throw bad_weak_ptr(); #else __builtin_abort(); #endif } 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() : _M_use_count(1), _M_weak_count(1) { } virtual ~_Sp_counted_base() // nothrow { } // Called when _M_use_count drops to zero, to release the resources // managed by *this. virtual void _M_dispose() = 0; // nothrow // Called when _M_weak_count drops to zero. virtual void _M_destroy() // nothrow { 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() // nothrow { // 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() // nothrow { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); } void _M_weak_release() // nothrow { // 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 // nothrow { // No memory barrier is used here so there is no synchronization // with other threads. return const_cast(_M_use_count); } private: _Sp_counted_base(_Sp_counted_base const&); _Sp_counted_base& operator=(_Sp_counted_base const&); _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; do { __count = _M_use_count; 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 (!__sync_bool_compare_and_swap(&_M_use_count, __count, __count + 1)); } // Forward declarations. template class __shared_ptr; template class __weak_ptr; template class __enable_shared_from_this; template class shared_ptr; template class weak_ptr; template struct owner_less; template 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 class _Sp_counted_ptr : public _Sp_counted_base<_Lp> { public: explicit _Sp_counted_ptr(_Ptr __p) : _M_ptr(__p) { } virtual void _M_dispose() // nothrow { delete _M_ptr; } virtual void _M_destroy() // nothrow { 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::_M_dispose() { } template<> inline void _Sp_counted_ptr::_M_dispose() { } template<> inline void _Sp_counted_ptr::_M_dispose() { } // Support for custom deleter and/or allocator template class _Sp_counted_deleter : public _Sp_counted_base<_Lp> { typedef typename _Alloc::template rebind<_Sp_counted_deleter>::other _My_alloc_type; // 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 _My_alloc_type // copy constructor must not throw { _Deleter _M_del; // copy constructor must not throw _My_Deleter(_Deleter __d, const _Alloc& __a) : _My_alloc_type(__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) { } virtual void _M_dispose() // nothrow { _M_del._M_del(_M_ptr); } virtual void _M_destroy() // nothrow { _My_alloc_type __a(_M_del); this->~_Sp_counted_deleter(); __a.deallocate(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 template struct _Sp_destroy_inplace { void operator()(_Tp* __p) const { if (__p) __p->~_Tp(); } }; struct _Sp_make_shared_tag { }; template class _Sp_counted_ptr_inplace : public _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp> { typedef _Sp_counted_deleter<_Tp*, _Sp_destroy_inplace<_Tp>, _Alloc, _Lp> _Base_type; public: explicit _Sp_counted_ptr_inplace(_Alloc __a) : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a) , _M_storage() { void* __p = &_M_storage; ::new (__p) _Tp(); // might throw _Base_type::_M_ptr = static_cast<_Tp*>(__p); } template _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) : _Base_type(static_cast<_Tp*>(0), _Sp_destroy_inplace<_Tp>(), __a) , _M_storage() { void* __p = &_M_storage; ::new (__p) _Tp(std::forward<_Args>(__args)...); // might throw _Base_type::_M_ptr = static_cast<_Tp*>(__p); } // Override because the allocator needs to know the dynamic type virtual void _M_destroy() // nothrow { typedef typename _Alloc::template rebind<_Sp_counted_ptr_inplace>::other _My_alloc_type; _My_alloc_type __a(_Base_type::_M_del); this->~_Sp_counted_ptr_inplace(); __a.deallocate(this, 1); } // Sneaky trick so __shared_ptr can get the managed pointer virtual void* _M_get_deleter(const std::type_info& __ti) { #ifdef __GXX_RTTI return __ti == typeid(_Sp_make_shared_tag) ? static_cast(&_M_storage) : _Base_type::_M_get_deleter(__ti); #else return 0; #endif } private: typename aligned_storage::value>::type _M_storage; }; template<_Lock_policy _Lp> class __shared_count { public: constexpr __shared_count() : _M_pi(0) // nothrow { } template 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 __shared_count(_Ptr __p, _Deleter __d) : _M_pi(0) { // The allocator's value_type doesn't matter, will rebind it anyway. typedef std::allocator _Alloc; typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; typedef std::allocator<_Sp_cd_type> _Alloc2; _Alloc2 __a2; __try { _M_pi = __a2.allocate(1); ::new(static_cast(_M_pi)) _Sp_cd_type(__p, __d); } __catch(...) { __d(__p); // Call _Deleter on __p. if (_M_pi) __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1); __throw_exception_again; } } template __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) { typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; typedef typename _Alloc::template rebind<_Sp_cd_type>::other _Alloc2; _Alloc2 __a2(__a); __try { _M_pi = __a2.allocate(1); ::new(static_cast(_M_pi)) _Sp_cd_type(__p, __d, __a); } __catch(...) { __d(__p); // Call _Deleter on __p. if (_M_pi) __a2.deallocate(static_cast<_Sp_cd_type*>(_M_pi), 1); __throw_exception_again; } } template __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 _Alloc::template rebind<_Sp_cp_type>::other _Alloc2; _Alloc2 __a2(__a); __try { _M_pi = __a2.allocate(1); ::new(static_cast(_M_pi)) _Sp_cp_type(__a, std::forward<_Args>(__args)...); } __catch(...) { if (_M_pi) __a2.deallocate(static_cast<_Sp_cp_type*>(_M_pi), 1); __throw_exception_again; } } #if _GLIBCXX_USE_DEPRECATED // Special case for auto_ptr<_Tp> to provide the strong guarantee. template explicit __shared_count(std::auto_ptr<_Tp>&& __r) : _M_pi(new _Sp_counted_ptr<_Tp*, _Lp>(__r.get())) { __r.release(); } #endif // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. template 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() // nothrow { if (_M_pi != 0) _M_pi->_M_release(); } __shared_count(const __shared_count& __r) : _M_pi(__r._M_pi) // nothrow { if (_M_pi != 0) _M_pi->_M_add_ref_copy(); } __shared_count& operator=(const __shared_count& __r) // nothrow { _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) // nothrow { _Sp_counted_base<_Lp>* __tmp = __r._M_pi; __r._M_pi = _M_pi; _M_pi = __tmp; } long _M_get_use_count() const // nothrow { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } bool _M_unique() const // nothrow { return this->_M_get_use_count() == 1; } void* _M_get_deleter(const std::type_info& __ti) const { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; } bool _M_less(const __shared_count& __rhs) const { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } bool _M_less(const __weak_count<_Lp>& __rhs) const { 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) { return __a._M_pi == __b._M_pi; } private: friend class __weak_count<_Lp>; template static _Sp_counted_base<_Lp>* _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, typename std::enable_if::value>::type* = 0) { return new _Sp_counted_deleter<_Tp*, _Del, std::allocator<_Tp>, _Lp>(__r.get(), __r.get_deleter()); } template static _Sp_counted_base<_Lp>* _S_create_from_up(std::unique_ptr<_Tp, _Del>&& __r, typename std::enable_if::value>::type* = 0) { typedef typename std::remove_reference<_Del>::type _Del1; typedef std::reference_wrapper<_Del1> _Del2; return new _Sp_counted_deleter<_Tp*, _Del2, std::allocator<_Tp>, _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() : _M_pi(0) // nothrow { } __weak_count(const __shared_count<_Lp>& __r) : _M_pi(__r._M_pi) // nothrow { if (_M_pi != 0) _M_pi->_M_weak_add_ref(); } __weak_count(const __weak_count<_Lp>& __r) : _M_pi(__r._M_pi) // nothrow { if (_M_pi != 0) _M_pi->_M_weak_add_ref(); } ~__weak_count() // nothrow { if (_M_pi != 0) _M_pi->_M_weak_release(); } __weak_count<_Lp>& operator=(const __shared_count<_Lp>& __r) // nothrow { _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) // nothrow { _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) // nothrow { _Sp_counted_base<_Lp>* __tmp = __r._M_pi; __r._M_pi = _M_pi; _M_pi = __tmp; } long _M_get_use_count() const // nothrow { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } bool _M_less(const __weak_count& __rhs) const { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } bool _M_less(const __shared_count<_Lp>& __rhs) const { 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) { 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*); // Friend of enable_shared_from_this. template void __enable_shared_from_this_helper(const __shared_count<>&, const enable_shared_from_this<_Tp1>*, const _Tp2*); template<_Lock_policy _Lp> inline void __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) { } template class __shared_ptr { public: typedef _Tp element_type; constexpr __shared_ptr() : _M_ptr(0), _M_refcount() // never throws { } template 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 __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 __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 __shared_ptr(nullptr_t __p, _Deleter __d) : _M_ptr(0), _M_refcount(__p, __d) { } template __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) : _M_ptr(0), _M_refcount(__p, __d, std::move(__a)) { } template __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p) : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws { } __shared_ptr(const __shared_ptr&) = default; // never throws __shared_ptr& operator=(const __shared_ptr&) = default; // never throws template::value>::type> __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws { } __shared_ptr(__shared_ptr&& __r) : _M_ptr(__r._M_ptr), _M_refcount() // never throws { _M_refcount._M_swap(__r._M_refcount); __r._M_ptr = 0; } template::value>::type> __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) : _M_ptr(__r._M_ptr), _M_refcount() // never throws { _M_refcount._M_swap(__r._M_refcount); __r._M_ptr = 0; } template 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 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r) : _M_ptr(__r.get()), _M_refcount() { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) _Tp1* __tmp = __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 __shared_ptr(std::auto_ptr<_Tp1>&& __r) : _M_ptr(__r.get()), _M_refcount() { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) static_assert( sizeof(_Tp1) > 0, "incomplete type" ); _Tp1* __tmp = __r.get(); _M_refcount = __shared_count<_Lp>(std::move(__r)); __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp); } #endif /* TODO: use delegating constructor */ constexpr __shared_ptr(nullptr_t) : _M_ptr(0), _M_refcount() // never throws { } template __shared_ptr& operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws { _M_ptr = __r._M_ptr; _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw return *this; } #if _GLIBCXX_USE_DEPRECATED template __shared_ptr& operator=(std::auto_ptr<_Tp1>&& __r) { __shared_ptr(std::move(__r)).swap(*this); return *this; } #endif __shared_ptr& operator=(__shared_ptr&& __r) { __shared_ptr(std::move(__r)).swap(*this); return *this; } template __shared_ptr& operator=(__shared_ptr<_Tp1, _Lp>&& __r) { __shared_ptr(std::move(__r)).swap(*this); return *this; } template __shared_ptr& operator=(std::unique_ptr<_Tp1, _Del>&& __r) { __shared_ptr(std::move(__r)).swap(*this); return *this; } void reset() // never throws { __shared_ptr().swap(*this); } template 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 void reset(_Tp1* __p, _Deleter __d) { __shared_ptr(__p, __d).swap(*this); } template 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 // never throws { _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); return *_M_ptr; } _Tp* operator->() const // never throws { _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); return _M_ptr; } _Tp* get() const // never throws { return _M_ptr; } explicit operator bool() const // never throws { return _M_ptr == 0 ? false : true; } bool unique() const // never throws { return _M_refcount._M_unique(); } long use_count() const // never throws { return _M_refcount._M_get_use_count(); } void swap(__shared_ptr<_Tp, _Lp>& __other) // never throws { std::swap(_M_ptr, __other._M_ptr); _M_refcount._M_swap(__other._M_refcount); } template bool owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const { return _M_refcount._M_less(__rhs._M_refcount); } template 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 __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 struct _Deleter { void operator()(_Tp* __ptr) { _M_alloc.destroy(__ptr); _M_alloc.deallocate(__ptr, 1); } _Alloc _M_alloc; }; template __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) }; _M_ptr = __del._M_alloc.allocate(1); __try { __del._M_alloc.construct(_M_ptr, std::forward<_Args>(__args)...); } __catch(...) { __del._M_alloc.deallocate(_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 friend __shared_ptr<_Tp1, _Lp1> __allocate_shared(const _Alloc& __a, _Args&&... __args); private: void* _M_get_deleter(const std::type_info& __ti) const { return _M_refcount._M_get_deleter(__ti); } template friend class __shared_ptr; template friend class __weak_ptr; template friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&); _Tp* _M_ptr; // Contained pointer. __shared_count<_Lp> _M_refcount; // Reference counter. }; // 20.8.13.2.7 shared_ptr comparisons template inline bool operator==(const __shared_ptr<_Tp1, _Lp>& __a, const __shared_ptr<_Tp2, _Lp>& __b) { return __a.get() == __b.get(); } template inline bool operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) { return __a.get() == nullptr; } template inline bool operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __b) { return nullptr == __b.get(); } template inline bool operator!=(const __shared_ptr<_Tp1, _Lp>& __a, const __shared_ptr<_Tp2, _Lp>& __b) { return __a.get() != __b.get(); } template inline bool operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) { return __a.get() != nullptr; } template inline bool operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __b) { return nullptr != __b.get(); } template inline bool operator<(const __shared_ptr<_Tp1, _Lp>& __a, const __shared_ptr<_Tp2, _Lp>& __b) { return __a.get() < __b.get(); } template struct _Sp_less : public binary_function<_Sp, _Sp, bool> { bool operator()(const _Sp& __lhs, const _Sp& __rhs) const { typedef typename _Sp::element_type element_type; return std::less()(__lhs.get(), __rhs.get()); } }; template struct less<__shared_ptr<_Tp, _Lp>> : public _Sp_less<__shared_ptr<_Tp, _Lp>> { }; // 2.2.3.8 shared_ptr specialized algorithms. template inline void swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) { __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 inline __shared_ptr<_Tp, _Lp> static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) { 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 inline __shared_ptr<_Tp, _Lp> const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) { 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 inline __shared_ptr<_Tp, _Lp> dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) { if (_Tp* __p = dynamic_cast<_Tp*>(__r.get())) return __shared_ptr<_Tp, _Lp>(__r, __p); return __shared_ptr<_Tp, _Lp>(); } template class __weak_ptr { public: typedef _Tp element_type; constexpr __weak_ptr() : _M_ptr(0), _M_refcount() // never throws { } // Generated copy constructor, assignment, destructor are fine. // The "obvious" converting constructor implementation: // // template // __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::value>::type> __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) : _M_refcount(__r._M_refcount) // never throws { _M_ptr = __r.lock().get(); } template::value>::type> __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws { } template __weak_ptr& operator=(const __weak_ptr<_Tp1, _Lp>& __r) // never throws { _M_ptr = __r.lock().get(); _M_refcount = __r._M_refcount; return *this; } template __weak_ptr& operator=(const __shared_ptr<_Tp1, _Lp>& __r) // never throws { _M_ptr = __r._M_ptr; _M_refcount = __r._M_refcount; return *this; } __shared_ptr<_Tp, _Lp> lock() const // never throws { #ifdef __GTHREADS // Optimization: avoid throw overhead. if (expired()) return __shared_ptr(); __try { return __shared_ptr(*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(); } #else // Optimization: avoid try/catch overhead when single threaded. return expired() ? __shared_ptr() : __shared_ptr(*this); #endif } // XXX MT long use_count() const // never throws { return _M_refcount._M_get_use_count(); } bool expired() const // never throws { return _M_refcount._M_get_use_count() == 0; } template bool owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const { return _M_refcount._M_less(__rhs._M_refcount); } template bool owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const { return _M_refcount._M_less(__rhs._M_refcount); } void reset() // never throws { __weak_ptr().swap(*this); } void swap(__weak_ptr& __s) // never throws { 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) { _M_ptr = __ptr; _M_refcount = __refcount; } template friend class __shared_ptr; template 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. }; // 20.8.13.3.7 weak_ptr specialized algorithms. template inline void swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) { __a.swap(__b); } template 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 struct owner_less<__shared_ptr<_Tp, _Lp>> : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> { }; template struct owner_less<__weak_ptr<_Tp, _Lp>> : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> { }; template class __enable_shared_from_this { protected: constexpr __enable_shared_from_this() { } __enable_shared_from_this(const __enable_shared_from_this&) { } __enable_shared_from_this& operator=(const __enable_shared_from_this&) { 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 shared_from_this() const { return __shared_ptr(this->_M_weak_this); } private: template void _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const { _M_weak_this._M_assign(__p, __n); } template friend void __enable_shared_from_this_helper(const __shared_count<_Lp>& __pn, const __enable_shared_from_this* __pe, const _Tp1* __px) { if (__pe != 0) __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); } mutable __weak_ptr<_Tp, _Lp> _M_weak_this; }; template 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 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 struct hash<__shared_ptr<_Tp, _Lp>> : public std::unary_function<__shared_ptr<_Tp, _Lp>, size_t> { size_t operator()(const __shared_ptr<_Tp, _Lp>& __s) const { return std::hash<_Tp*>()(__s.get()); } }; _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif // _SHARED_PTR_BASE_H