// <tr1/shared_ptr.h> -*- C++ -*- // Copyright (C) 2007-2020 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/>. // 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) // GCC Note: based on version 1.32.0 of the Boost library. /** @file tr1/shared_ptr.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{tr1/memory} */ #ifndef _TR1_SHARED_PTR_H #define _TR1_SHARED_PTR_H 1 namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace tr1 { /** * @brief Exception possibly thrown by @c shared_ptr. * @ingroup exceptions */ class bad_weak_ptr : public std::exception { public: virtual char const* what() const throw() { return "tr1::bad_weak_ptr"; } }; // 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() : _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) { __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() // 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() __atomic_thread_fence (__ATOMIC_ACQ_REL); } _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<const volatile _Atomic_word&>(_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 = _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)); } template<typename _Ptr, typename _Deleter, _Lock_policy _Lp> class _Sp_counted_base_impl : public _Sp_counted_base<_Lp> { public: // Precondition: __d(__p) must not throw. _Sp_counted_base_impl(_Ptr __p, _Deleter __d) : _M_ptr(__p), _M_del(__d) { } virtual void _M_dispose() // nothrow { _M_del(_M_ptr); } virtual void* _M_get_deleter(const std::type_info& __ti) { #if __cpp_rtti return __ti == typeid(_Deleter) ? &_M_del : 0; #else return 0; #endif } private: _Sp_counted_base_impl(const _Sp_counted_base_impl&); _Sp_counted_base_impl& operator=(const _Sp_counted_base_impl&); _Ptr _M_ptr; // copy constructor must not throw _Deleter _M_del; // copy constructor must not throw }; template<_Lock_policy _Lp = __default_lock_policy> class __weak_count; template<typename _Tp> struct _Sp_deleter { typedef void result_type; typedef _Tp* argument_type; void operator()(_Tp* __p) const { delete __p; } }; template<_Lock_policy _Lp = __default_lock_policy> class __shared_count { public: __shared_count() : _M_pi(0) // nothrow { } template<typename _Ptr> __shared_count(_Ptr __p) : _M_pi(0) { __try { typedef typename std::tr1::remove_pointer<_Ptr>::type _Tp; _M_pi = new _Sp_counted_base_impl<_Ptr, _Sp_deleter<_Tp>, _Lp>( __p, _Sp_deleter<_Tp>()); } __catch(...) { delete __p; __throw_exception_again; } } template<typename _Ptr, typename _Deleter> __shared_count(_Ptr __p, _Deleter __d) : _M_pi(0) { __try { _M_pi = new _Sp_counted_base_impl<_Ptr, _Deleter, _Lp>(__p, __d); } __catch(...) { __d(__p); // Call _Deleter on __p. __throw_exception_again; } } // Special case for auto_ptr<_Tp> to provide the strong guarantee. template<typename _Tp> explicit __shared_count(std::auto_ptr<_Tp>& __r) : _M_pi(new _Sp_counted_base_impl<_Tp*, _Sp_deleter<_Tp>, _Lp >(__r.get(), _Sp_deleter<_Tp>())) { __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; } friend inline bool operator==(const __shared_count& __a, const __shared_count& __b) { return __a._M_pi == __b._M_pi; } friend inline bool operator<(const __shared_count& __a, const __shared_count& __b) { return std::less<_Sp_counted_base<_Lp>*>()(__a._M_pi, __b._M_pi); } void* _M_get_deleter(const std::type_info& __ti) const { return _M_pi ? _M_pi->_M_get_deleter(__ti) : 0; } private: friend class __weak_count<_Lp>; _Sp_counted_base<_Lp>* _M_pi; }; template<_Lock_policy _Lp> class __weak_count { public: __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; } friend inline bool operator==(const __weak_count<_Lp>& __a, const __weak_count<_Lp>& __b) { return __a._M_pi == __b._M_pi; } friend inline bool operator<(const __weak_count<_Lp>& __a, const __weak_count<_Lp>& __b) { return std::less<_Sp_counted_base<_Lp>*>()(__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(); } // 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> class enable_shared_from_this; // 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<typename _Tp1, typename _Tp2> 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>&, ...) { } struct __static_cast_tag { }; struct __const_cast_tag { }; struct __dynamic_cast_tag { }; // A smart pointer with reference-counted copy semantics. The // object pointed to is deleted when the last shared_ptr pointing to // it is destroyed or reset. template<typename _Tp, _Lock_policy _Lp> class __shared_ptr { public: typedef _Tp element_type; __shared_ptr() : _M_ptr(0), _M_refcount() // never throws { } template<typename _Tp1> explicit __shared_ptr(_Tp1* __p) : _M_ptr(__p), _M_refcount(__p) { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) typedef int _IsComplete[sizeof(_Tp1)]; __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); } // generated copy constructor, assignment, destructor are fine. template<typename _Tp1> __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) } 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 (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED // Postcondition: use_count() == 1 and __r.get() == 0 template<typename _Tp1> explicit __shared_ptr(std::auto_ptr<_Tp1>& __r) : _M_ptr(__r.get()), _M_refcount() { // TODO requries delete __r.release() well-formed __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) typedef int _IsComplete[sizeof(_Tp1)]; _Tp1* __tmp = __r.get(); _M_refcount = __shared_count<_Lp>(__r); __enable_shared_from_this_helper(_M_refcount, __tmp, __tmp); } #endif template<typename _Tp1> __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, __static_cast_tag) : _M_ptr(static_cast<element_type*>(__r._M_ptr)), _M_refcount(__r._M_refcount) { } template<typename _Tp1> __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, __const_cast_tag) : _M_ptr(const_cast<element_type*>(__r._M_ptr)), _M_refcount(__r._M_refcount) { } template<typename _Tp1> __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, __dynamic_cast_tag) : _M_ptr(dynamic_cast<element_type*>(__r._M_ptr)), _M_refcount(__r._M_refcount) { if (_M_ptr == 0) // need to allocate new counter -- the cast failed _M_refcount = __shared_count<_Lp>(); } template<typename _Tp1> __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 (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED template<typename _Tp1> __shared_ptr& operator=(std::auto_ptr<_Tp1>& __r) { __shared_ptr(__r).swap(*this); return *this; } #endif void reset() // never throws { __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); } // Allow class instantiation when _Tp is [cv-qual] void. typename std::tr1::add_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; } // Implicit conversion to "bool" private: typedef _Tp* __shared_ptr::*__unspecified_bool_type; public: operator __unspecified_bool_type() const // never throws { return _M_ptr == 0 ? 0 : &__shared_ptr::_M_ptr; } 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); } private: void* _M_get_deleter(const std::type_info& __ti) const { return _M_refcount._M_get_deleter(__ti); } template<typename _Tp1, _Lock_policy _Lp1> bool _M_less(const __shared_ptr<_Tp1, _Lp1>& __rhs) const { return _M_refcount < __rhs._M_refcount; } 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>&); // Friends injected into enclosing namespace and found by ADL: template<typename _Tp1> friend inline bool operator==(const __shared_ptr& __a, const __shared_ptr<_Tp1, _Lp>& __b) { return __a.get() == __b.get(); } template<typename _Tp1> friend inline bool operator!=(const __shared_ptr& __a, const __shared_ptr<_Tp1, _Lp>& __b) { return __a.get() != __b.get(); } template<typename _Tp1> friend inline bool operator<(const __shared_ptr& __a, const __shared_ptr<_Tp1, _Lp>& __b) { return __a._M_less(__b); } _Tp* _M_ptr; // Contained pointer. __shared_count<_Lp> _M_refcount; // Reference counter. }; // 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) { __a.swap(__b); } // 2.2.3.9 shared_ptr casts /* The seemingly equivalent * shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) * will eventually result in undefined behaviour, * attempting to delete the same object twice. */ template<typename _Tp, typename _Tp1, _Lock_policy _Lp> inline __shared_ptr<_Tp, _Lp> static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) { return __shared_ptr<_Tp, _Lp>(__r, __static_cast_tag()); } /* The seemingly equivalent * shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) * will eventually result in undefined behaviour, * attempting to delete the same object twice. */ template<typename _Tp, typename _Tp1, _Lock_policy _Lp> inline __shared_ptr<_Tp, _Lp> const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) { return __shared_ptr<_Tp, _Lp>(__r, __const_cast_tag()); } /* The seemingly equivalent * shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) * will eventually result in undefined behaviour, * attempting to delete the same object twice. */ template<typename _Tp, typename _Tp1, _Lock_policy _Lp> inline __shared_ptr<_Tp, _Lp> dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) { return __shared_ptr<_Tp, _Lp>(__r, __dynamic_cast_tag()); } // 2.2.3.7 shared_ptr I/O template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp> std::basic_ostream<_Ch, _Tr>& operator<<(std::basic_ostream<_Ch, _Tr>& __os, const __shared_ptr<_Tp, _Lp>& __p) { __os << __p.get(); return __os; } // 2.2.3.10 shared_ptr get_deleter (experimental) template<typename _Del, typename _Tp, _Lock_policy _Lp> inline _Del* get_deleter(const __shared_ptr<_Tp, _Lp>& __p) { #if __cpp_rtti return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); #else return 0; #endif } template<typename _Tp, _Lock_policy _Lp> class __weak_ptr { public: typedef _Tp element_type; __weak_ptr() : _M_ptr(0), _M_refcount() // never throws { } // Generated copy constructor, assignment, destructor are fine. // 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> __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) : _M_refcount(__r._M_refcount) // never throws { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) _M_ptr = __r.lock().get(); } template<typename _Tp1> __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) } template<typename _Tp1> __weak_ptr& operator=(const __weak_ptr<_Tp1, _Lp>& __r) // never throws { _M_ptr = __r.lock().get(); _M_refcount = __r._M_refcount; return *this; } template<typename _Tp1> __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<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 // never throws { return _M_refcount._M_get_use_count(); } bool expired() const // never throws { return _M_refcount._M_get_use_count() == 0; } 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<typename _Tp1> bool _M_less(const __weak_ptr<_Tp1, _Lp>& __rhs) const { return _M_refcount < __rhs._M_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>; // Friend injected into namespace and found by ADL. template<typename _Tp1> friend inline bool operator<(const __weak_ptr& __lhs, const __weak_ptr<_Tp1, _Lp>& __rhs) { return __lhs._M_less(__rhs); } _Tp* _M_ptr; // Contained pointer. __weak_count<_Lp> _M_refcount; // Reference counter. }; // 2.2.4.7 weak_ptr specialized algorithms. template<typename _Tp, _Lock_policy _Lp> inline void swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) { __a.swap(__b); } template<typename _Tp, _Lock_policy _Lp> class __enable_shared_from_this { protected: __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<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 { _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) { if (__pe != 0) __pe->_M_weak_assign(const_cast<_Tp1*>(__px), __pn); } mutable __weak_ptr<_Tp, _Lp> _M_weak_this; }; // The actual shared_ptr, with forwarding constructors and // assignment operators. template<typename _Tp> class shared_ptr : public __shared_ptr<_Tp> { public: shared_ptr() : __shared_ptr<_Tp>() { } template<typename _Tp1> explicit shared_ptr(_Tp1* __p) : __shared_ptr<_Tp>(__p) { } template<typename _Tp1, typename _Deleter> shared_ptr(_Tp1* __p, _Deleter __d) : __shared_ptr<_Tp>(__p, __d) { } template<typename _Tp1> shared_ptr(const shared_ptr<_Tp1>& __r) : __shared_ptr<_Tp>(__r) { } template<typename _Tp1> explicit shared_ptr(const weak_ptr<_Tp1>& __r) : __shared_ptr<_Tp>(__r) { } #if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED template<typename _Tp1> explicit shared_ptr(std::auto_ptr<_Tp1>& __r) : __shared_ptr<_Tp>(__r) { } #endif template<typename _Tp1> shared_ptr(const shared_ptr<_Tp1>& __r, __static_cast_tag) : __shared_ptr<_Tp>(__r, __static_cast_tag()) { } template<typename _Tp1> shared_ptr(const shared_ptr<_Tp1>& __r, __const_cast_tag) : __shared_ptr<_Tp>(__r, __const_cast_tag()) { } template<typename _Tp1> shared_ptr(const shared_ptr<_Tp1>& __r, __dynamic_cast_tag) : __shared_ptr<_Tp>(__r, __dynamic_cast_tag()) { } template<typename _Tp1> shared_ptr& operator=(const shared_ptr<_Tp1>& __r) // never throws { this->__shared_ptr<_Tp>::operator=(__r); return *this; } #if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED template<typename _Tp1> shared_ptr& operator=(std::auto_ptr<_Tp1>& __r) { this->__shared_ptr<_Tp>::operator=(__r); return *this; } #endif }; // 2.2.3.8 shared_ptr specialized algorithms. template<typename _Tp> inline void swap(__shared_ptr<_Tp>& __a, __shared_ptr<_Tp>& __b) { __a.swap(__b); } template<typename _Tp, typename _Tp1> inline shared_ptr<_Tp> static_pointer_cast(const shared_ptr<_Tp1>& __r) { return shared_ptr<_Tp>(__r, __static_cast_tag()); } template<typename _Tp, typename _Tp1> inline shared_ptr<_Tp> const_pointer_cast(const shared_ptr<_Tp1>& __r) { return shared_ptr<_Tp>(__r, __const_cast_tag()); } template<typename _Tp, typename _Tp1> inline shared_ptr<_Tp> dynamic_pointer_cast(const shared_ptr<_Tp1>& __r) { return shared_ptr<_Tp>(__r, __dynamic_cast_tag()); } // The actual weak_ptr, with forwarding constructors and // assignment operators. template<typename _Tp> class weak_ptr : public __weak_ptr<_Tp> { public: weak_ptr() : __weak_ptr<_Tp>() { } template<typename _Tp1> weak_ptr(const weak_ptr<_Tp1>& __r) : __weak_ptr<_Tp>(__r) { } template<typename _Tp1> weak_ptr(const shared_ptr<_Tp1>& __r) : __weak_ptr<_Tp>(__r) { } template<typename _Tp1> weak_ptr& operator=(const weak_ptr<_Tp1>& __r) // never throws { this->__weak_ptr<_Tp>::operator=(__r); return *this; } template<typename _Tp1> weak_ptr& operator=(const shared_ptr<_Tp1>& __r) // never throws { this->__weak_ptr<_Tp>::operator=(__r); return *this; } shared_ptr<_Tp> lock() const // never throws { #ifdef __GTHREADS if (this->expired()) return shared_ptr<_Tp>(); __try { return shared_ptr<_Tp>(*this); } __catch(const bad_weak_ptr&) { return shared_ptr<_Tp>(); } #else return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this); #endif } }; template<typename _Tp> class enable_shared_from_this { protected: 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> shared_from_this() { return shared_ptr<_Tp>(this->_M_weak_this); } shared_ptr<const _Tp> shared_from_this() const { return shared_ptr<const _Tp>(this->_M_weak_this); } private: template<typename _Tp1> void _M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const { _M_weak_this._M_assign(__p, __n); } template<typename _Tp1> friend void __enable_shared_from_this_helper(const __shared_count<>& __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> _M_weak_this; }; } _GLIBCXX_END_NAMESPACE_VERSION } #endif // _TR1_SHARED_PTR_H