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// <tr1/boost_shared_ptr.h> -*- C++ -*- // Copyright (C) 2005 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 2, 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. // You should have received a copy of the GNU General Public License along // with this library; see the file COPYING. If not, write to the Free // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, // USA. // As a special exception, you may use this file as part of a free software // library without restriction. Specifically, if other files instantiate // templates or use macros or inline functions from this file, or you compile // this file and link it with other files to produce an executable, this // file does not by itself cause the resulting executable to be covered by // the GNU General Public License. This exception does not however // invalidate any other reasons why the executable file might be covered by // the GNU General Public License. // 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 boost_memory.h * This is an internal header file, included by other library headers. * You should not attempt to use it directly. */ #ifndef _BOOST_SHARED_PTR_H #define _BOOST_SHARED_PTR_H 1 // namespace std::tr1 namespace std { namespace tr1 { class bad_weak_ptr : public std::exception { public: virtual char const* what() const throw() { return "tr1::bad_weak_ptr"; } }; // Helper for exception objects in <tr1/memory> // TODO this should be defined in a different file. inline void __throw_bad_weak_ptr() { #if __EXCEPTIONS throw bad_weak_ptr(); #else std::abort(); #endif } template<typename _Tp> struct _Sp_deleter { typedef void result_type; typedef _Tp* argument_type; void operator()(_Tp* p) const { delete p; } }; class _Sp_counted_base { public: _Sp_counted_base() : _M_use_count(1), _M_weak_count(1) { // For the case of __GTHREAD_MUTEX_INIT we haven't initialised // the mutex yet, so do it now. #if defined(__GTHREADS) && defined(__GTHREAD_MUTEX_INIT) __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT; _M_mutex = __tmp; #endif } virtual ~_Sp_counted_base() // nothrow { } // dispose() is called when _M_use_count drops to zero, to release // the resources managed by *this. virtual void dispose() = 0; // nothrow // destroy() is called when _M_weak_count drops to zero. virtual void destroy() // nothrow { delete this; } virtual void* get_deleter(const std::type_info&) = 0; void add_ref_copy() { __gnu_cxx::__atomic_add(&_M_use_count, 1); } void add_ref_lock() { __gnu_cxx::lock lock(_M_mutex); if (__gnu_cxx::__exchange_and_add(&_M_use_count, 1) == 0) { _M_use_count = 0; __throw_bad_weak_ptr(); } } void release() // nothrow { if (__gnu_cxx::__exchange_and_add(&_M_use_count, -1) == 1) { dispose(); #ifdef __GTHREADS _GLIBCXX_READ_MEM_BARRIER; _GLIBCXX_WRITE_MEM_BARRIER; #endif if (__gnu_cxx::__exchange_and_add(&_M_weak_count, -1) == 1) destroy(); } } void weak_add_ref() // nothrow { __gnu_cxx::__atomic_add(&_M_weak_count, 1); } void weak_release() // nothrow { if (__gnu_cxx::__exchange_and_add(&_M_weak_count, -1) == 1) { #ifdef __GTHREADS _GLIBCXX_READ_MEM_BARRIER; _GLIBCXX_WRITE_MEM_BARRIER; #endif destroy(); } } long use_count() const // nothrow { return _M_use_count; // XXX is this MT safe? } 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) __gnu_cxx::mutex_type _M_mutex; }; template<typename _Ptr, typename _Deleter> class _Sp_counted_base_impl : public _Sp_counted_base { public: /** * @brief * @pre d(p) must not throw. */ _Sp_counted_base_impl(_Ptr __p, _Deleter __d) : _M_ptr(__p), _M_del(__d) { } virtual void dispose() // nothrow { _M_del(_M_ptr); } virtual void* get_deleter(const std::type_info& __ti) { return __ti == typeid(_Deleter) ? &_M_del : 0; } 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 }; class weak_count; class shared_count { private: _Sp_counted_base* _M_pi; friend class weak_count; public: shared_count() : _M_pi(0) // nothrow { } template<typename _Ptr, typename _Deleter> shared_count(_Ptr __p, _Deleter __d) : _M_pi(0) { try { _M_pi = new _Sp_counted_base_impl<_Ptr, _Deleter>(__p, __d); } catch(...) { __d(__p); // delete __p __throw_exception_again; } } // auto_ptr<_Tp> is special cased 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> >(__r.get(), _Sp_deleter<_Tp>())) { __r.release(); } // throws bad_weak_ptr when __r.use_count() == 0 explicit shared_count(const weak_count& __r); ~shared_count() // nothrow { if (_M_pi != 0) _M_pi->release(); } shared_count(const shared_count& __r) : _M_pi(__r._M_pi) // nothrow { if (_M_pi != 0) _M_pi->add_ref_copy(); } shared_count& operator=(const shared_count& __r) // nothrow { _Sp_counted_base* __tmp = __r._M_pi; if(__tmp != _M_pi) { if(__tmp != 0) __tmp->add_ref_copy(); if(_M_pi != 0) _M_pi->release(); _M_pi = __tmp; } return *this; } void swap(shared_count& __r) // nothrow { _Sp_counted_base* __tmp = __r._M_pi; __r._M_pi = _M_pi; _M_pi = __tmp; } long use_count() const // nothrow { return _M_pi != 0 ? _M_pi->use_count() : 0; } bool unique() const // nothrow { return this->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*>()(__a._M_pi, __b._M_pi); } void* get_deleter(const std::type_info& __ti) const { return _M_pi ? _M_pi->get_deleter(__ti) : 0; } }; class weak_count { private: _Sp_counted_base* _M_pi; friend class shared_count; public: weak_count() : _M_pi(0) // nothrow { } weak_count(const shared_count& __r) : _M_pi(__r._M_pi) // nothrow { if (_M_pi != 0) _M_pi->weak_add_ref(); } weak_count(const weak_count& __r) : _M_pi(__r._M_pi) // nothrow { if (_M_pi != 0) _M_pi->weak_add_ref(); } ~weak_count() // nothrow { if (_M_pi != 0) _M_pi->weak_release(); } weak_count& operator=(const shared_count& __r) // nothrow { _Sp_counted_base* __tmp = __r._M_pi; if (__tmp != 0) __tmp->weak_add_ref(); if (_M_pi != 0) _M_pi->weak_release(); _M_pi = __tmp; return *this; } weak_count& operator=(const weak_count& __r) // nothrow { _Sp_counted_base * __tmp = __r._M_pi; if (__tmp != 0) __tmp->weak_add_ref(); if (_M_pi != 0) _M_pi->weak_release(); _M_pi = __tmp; return *this; } void swap(weak_count& __r) // nothrow { _Sp_counted_base * __tmp = __r._M_pi; __r._M_pi = _M_pi; _M_pi = __tmp; } long use_count() const // nothrow { return _M_pi != 0 ? _M_pi->use_count() : 0; } friend inline bool operator==(const weak_count& __a, const weak_count& __b) { return __a._M_pi == __b._M_pi; } friend inline bool operator<(const weak_count& __a, const weak_count& __b) { return std::less<_Sp_counted_base*>()(__a._M_pi, __b._M_pi); } }; inline shared_count::shared_count(const weak_count& __r) : _M_pi(__r._M_pi) { if (_M_pi != 0) _M_pi->add_ref_lock(); else __throw_bad_weak_ptr(); } // fwd decls template<typename _Tp> class shared_ptr; template<typename _Tp> class weak_ptr; template<typename _Tp> class enable_shared_from_this; struct __static_cast_tag {}; struct __const_cast_tag {}; struct __dynamic_cast_tag {}; struct __polymorphic_cast_tag {}; template<class _Tp> struct shared_ptr_traits { typedef _Tp& reference; }; template<> struct shared_ptr_traits<void> { typedef void reference; }; template<> struct shared_ptr_traits<void const> { typedef void reference; }; template<> struct shared_ptr_traits<void volatile> { typedef void reference; }; template<> struct shared_ptr_traits<void const volatile> { typedef void reference; }; // enable_shared_from_this support // friend of enable_shared_from_this template<typename _Tp1, typename _Tp2> void __enable_shared_from_this(const shared_count& __pn, const enable_shared_from_this<_Tp1>* __pe, const _Tp2* __px ); inline void __enable_shared_from_this(const shared_count&, ...) { } // get_deleter must be declared before friend declaration by shared_ptr. template<typename _Del, typename _Tp> _Del* get_deleter(const shared_ptr<_Tp>&); /** * @class shared_ptr <tr1/memory> * * A smart pointer with reference-counted copy semantics. * The object pointed to is deleted when the last shared_ptr pointing to it * is destroyed or reset. */ template<typename _Tp> class shared_ptr { typedef typename shared_ptr_traits<_Tp>::reference _Reference; public: typedef _Tp element_type; /** @brief Construct an empty %shared_ptr. * @post use_count()==0 && get()==0 */ shared_ptr() : _M_ptr(0), _M_refcount() // never throws { } /** @brief Construct a %shared_ptr that owns the pointer @a p. * @param p A pointer that is convertible to element_type*. * @post use_count() == 1 && get() == p * @throw std::bad_alloc, in which case @c delete @a p is called. */ template<typename _Tp1> explicit shared_ptr(_Tp1* __p) : _M_ptr(__p), _M_refcount(__p, _Sp_deleter<_Tp1>()) { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) // __glibcxx_function_requires(_CompleteConcept<_Tp1*>) __enable_shared_from_this( _M_refcount, __p, __p ); } // // Requirements: D's copy constructor and destructor must not throw // // shared_ptr will release p by calling d(p) // /** @brief Construct a %shared_ptr that owns the pointer @a p * and the deleter @a d. * @param p A pointer. * @param d A deleter. * @post use_count() == 1 && get() == p * @throw std::bad_alloc, in which case @a d(p) is called. */ 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 D is CopyConstructible and d(p) well-formed __enable_shared_from_this( _M_refcount, __p, __p ); } // generated copy constructor, assignment, destructor are fine. /** @brief If @a r is empty, constructs an empty %shared_ptr; otherwise * construct a %shared_ptr that shares ownership with @a r. * @param r A %shared_ptr. * @post get() == r.get() && use_count() == r.use_count() * @throw std::bad_alloc, in which case */ template<typename _Tp1> shared_ptr(const shared_ptr<_Tp1>& __r) : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) } /** @brief Constructs a %shared_ptr that shares ownership with @a r * and stores a copy of the pointer stored in @a r. * @param r A weak_ptr. * @post use_count() == r.use_count() * @throw bad_weak_ptr when r.expired(), * in which case the constructor has no effect. */ template<typename _Tp1> explicit shared_ptr(const weak_ptr<_Tp1>& __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; } /** * @post 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 requires r.release() convertible to _Tp*, Tp1 is complete, // delete r.release() well-formed _Tp1 * __tmp = __r.get(); _M_refcount = shared_count(__r); __enable_shared_from_this( _M_refcount, __tmp, __tmp ); } template<typename _Tp1> shared_ptr(const shared_ptr<_Tp1>& __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>& __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>& __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(); } template<typename _Tp1> shared_ptr& operator=(const shared_ptr<_Tp1>& __r) // never throws { _M_ptr = __r._M_ptr; _M_refcount = __r._M_refcount; // shared_count::op= doesn't throw return *this; } template<typename _Tp1> shared_ptr& operator=(std::auto_ptr<_Tp1>& __r) { shared_ptr(__r).swap(*this); return *this; } void reset() // never throws { shared_ptr().swap(*this); } template<typename _Tp1> void reset(_Tp1* __p) // _Tp1 must be complete { _GLIBCXX_DEBUG_ASSERT(__p == 0 || __p != _M_ptr); // catch self-reset // errors shared_ptr(__p).swap(*this); } template<typename _Tp1, typename _Deleter> void reset(_Tp1 * __p, _Deleter __d) { shared_ptr(__p, __d).swap(*this); } // error to instantiate if _Tp is [cv-qual] void _Reference 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.unique(); } long use_count() const // never throws { return _M_refcount.use_count(); } void swap(shared_ptr<_Tp>& __other) // never throws { std::swap(_M_ptr, __other._M_ptr); _M_refcount.swap(__other._M_refcount); } private: void* _M_get_deleter(const std::type_info& __ti) const { return _M_refcount.get_deleter(__ti); } template<typename _Tp1> bool _M_less(const shared_ptr<_Tp1>& __rhs) const { return _M_refcount < __rhs._M_refcount; } template<typename _Tp1> friend class shared_ptr; template<typename _Tp1> friend class weak_ptr; template<typename _Del, typename _Tp1> friend _Del* get_deleter(const shared_ptr<_Tp1>&); // friends injected into enclosing namespace and found by ADL: template<typename _Tp1> friend inline bool operator==(const shared_ptr& __a, const shared_ptr<_Tp1>& __b) { return __a.get() == __b.get(); } template<typename _Tp1> friend inline bool operator!=(const shared_ptr& __a, const shared_ptr<_Tp1>& __b) { return __a.get() != __b.get(); } template<typename _Tp1> friend inline bool operator<(const shared_ptr& __a, const shared_ptr<_Tp1>& __b) { return __a._M_less(__b); } _Tp* _M_ptr; // contained pointer shared_count _M_refcount; // reference counter }; // shared_ptr // 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); } // 2.2.3.9 shared_ptr casts /** @warning The seemingly equivalent * <code>shared_ptr<T>(static_cast<T*>(r.get()))</code> * will eventually result in undefined behaviour, * attempting to delete the same object twice. */ template<typename _Tp, typename _Tp1> shared_ptr<_Tp> static_pointer_cast(const shared_ptr<_Tp1>& __r) { return shared_ptr<_Tp>(__r, __static_cast_tag()); } /** @warning The seemingly equivalent * <code>shared_ptr<T>(const_cast<T*>(r.get()))</code> * will eventually result in undefined behaviour, * attempting to delete the same object twice. */ template<typename _Tp, typename _Tp1> shared_ptr<_Tp> const_pointer_cast(const shared_ptr<_Tp1>& __r) { return shared_ptr<_Tp>(__r, __const_cast_tag()); } /** @warning The seemingly equivalent * <code>shared_ptr<T>(dynamic_cast<T*>(r.get()))</code> * will eventually result in undefined behaviour, * attempting to delete the same object twice. */ template<typename _Tp, typename _Tp1> shared_ptr<_Tp> dynamic_pointer_cast(const shared_ptr<_Tp1>& __r) { return shared_ptr<_Tp>(__r, __dynamic_cast_tag()); } // 2.2.3.7 shared_ptr I/O template<typename _Ch, typename _Tr, typename _Tp> std::basic_ostream<_Ch, _Tr>& operator<<(std::basic_ostream<_Ch, _Tr>& __os, const shared_ptr<_Tp>& __p) { __os << __p.get(); return __os; } // 2.2.3.10 shared_ptr get_deleter (experimental) template<typename _Del, typename _Tp> inline _Del* get_deleter(const shared_ptr<_Tp>& __p) { return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del))); } template<typename _Tp> 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<class Y> // weak_ptr(weak_ptr<Y> const & 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>& 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>& 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>& 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>& r) // never throws { _M_ptr = r._M_ptr; _M_refcount = r._M_refcount; return *this; } shared_ptr<_Tp> lock() const // never throws { #ifdef __GTHREADS // optimization: avoid throw overhead if (expired()) return shared_ptr<element_type>(); try { return shared_ptr<element_type>(*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>(); } #else // optimization: avoid try/catch overhead when single threaded return expired() ? shared_ptr<element_type>() : shared_ptr<element_type>(*this); #endif } // XXX MT long use_count() const // never throws { return _M_refcount.use_count(); } bool expired() const // never throws { return _M_refcount.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.swap(__s._M_refcount); } private: template<typename _Tp1> bool _M_less(const weak_ptr<_Tp1>& __rhs) const { return _M_refcount < __rhs._M_refcount; } // used by __enable_shared_from_this void _M_assign(_Tp* __ptr, const shared_count& __refcount) { _M_ptr = __ptr; _M_refcount = __refcount; } // friend injected into namespace and found by ADL template<typename _Tp1> friend inline bool operator<(const weak_ptr& __lhs, const weak_ptr<_Tp1>& __rhs) { return __lhs._M_less(__rhs); } template<typename _Tp1> friend class weak_ptr; template<typename _Tp1> friend class shared_ptr; friend class enable_shared_from_this<_Tp>; _Tp* _M_ptr; // contained pointer weak_count _M_refcount; // reference counter }; // weak_ptr // 2.2.4.7 weak_ptr specialized algorithms. template<typename _Tp> void swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) { __a.swap(__b); } 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() { shared_ptr<_Tp> __p(this->_M_weak_this); return __p; } shared_ptr<const _Tp> shared_from_this() const { shared_ptr<const _Tp> __p(this->_M_weak_this); return __p; } 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(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; }; } // namespace tr1 } // namespace std #endif
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