forked from boostorg/smart_ptr
456 lines
9.4 KiB
C++
456 lines
9.4 KiB
C++
#ifndef BOOST_DETAIL_SHARED_COUNT_HPP_INCLUDED
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#define BOOST_DETAIL_SHARED_COUNT_HPP_INCLUDED
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#if _MSC_VER >= 1020
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#pragma once
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#endif
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//
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// detail/shared_count.hpp
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//
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// Copyright (c) 2001, 2002 Peter Dimov and Multi Media Ltd.
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all copies.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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#include <boost/config.hpp>
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#ifndef BOOST_NO_AUTO_PTR
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# include <memory>
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#endif
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#include <boost/checked_delete.hpp>
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#include <boost/throw_exception.hpp>
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#include <boost/detail/lightweight_mutex.hpp>
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#include <functional> // for std::less
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#include <exception> // for std::exception
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#include <new> // for std::bad_alloc
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#ifdef __BORLANDC__
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# pragma warn -8026 // Functions with excep. spec. are not expanded inline
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# pragma warn -8027 // Functions containing try are not expanded inline
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#endif
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namespace boost
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{
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// Debug hooks
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#if defined(BOOST_ENABLE_SHARED_PTR_DEBUG_HOOKS)
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void shared_ptr_constructor_hook(void * p);
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void shared_ptr_destructor_hook(void * p);
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#endif
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// The standard library that comes with Borland C++ 5.5.1
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// defines std::exception and its members as having C calling
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// convention (-pc). When the definition of bad_weak_ptr
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// is compiled with -ps, the compiler issues an error.
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// Hence, the temporary #pragma option -pc below. The version
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// check is deliberately conservative.
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#if defined(__BORLANDC__) && __BORLANDC__ == 0x551
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# pragma option push -pc
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#endif
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class bad_weak_ptr: public std::exception
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{
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public:
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virtual char const * what() const throw()
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{
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return "boost::bad_weak_ptr";
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}
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};
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#if defined(__BORLANDC__) && __BORLANDC__ == 0x551
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# pragma option pop
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#endif
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namespace detail
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{
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class counted_base
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{
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private:
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typedef detail::lightweight_mutex mutex_type;
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public:
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counted_base(): use_count_(1), weak_count_(1)
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{
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}
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virtual ~counted_base() // nothrow
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{
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}
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// dispose() is called when use_count_ drops to zero, to release
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// the resources managed by *this.
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virtual void dispose() = 0; // nothrow
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// destruct() is called when weak_count_ drops to zero.
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virtual void destruct() // nothrow
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{
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delete this;
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}
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void add_ref()
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{
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#if defined(BOOST_HAS_THREADS)
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mutex_type::scoped_lock lock(mtx_);
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#endif
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if(use_count_ == 0 && weak_count_ != 0) boost::throw_exception(boost::bad_weak_ptr());
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++use_count_;
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++weak_count_;
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}
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void release() // nothrow
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{
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{
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#if defined(BOOST_HAS_THREADS)
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mutex_type::scoped_lock lock(mtx_);
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#endif
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long new_use_count = --use_count_;
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if(new_use_count != 0)
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{
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--weak_count_;
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return;
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}
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}
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dispose();
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weak_release();
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}
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void weak_add_ref() // nothrow
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{
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#if defined(BOOST_HAS_THREADS)
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mutex_type::scoped_lock lock(mtx_);
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#endif
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++weak_count_;
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}
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void weak_release() // nothrow
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{
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long new_weak_count;
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{
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#if defined(BOOST_HAS_THREADS)
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mutex_type::scoped_lock lock(mtx_);
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#endif
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new_weak_count = --weak_count_;
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}
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if(new_weak_count == 0)
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{
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destruct();
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}
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}
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long use_count() const // nothrow
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{
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#if defined(BOOST_HAS_THREADS)
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mutex_type::scoped_lock lock(mtx_);
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#endif
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return use_count_;
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}
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private:
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counted_base(counted_base const &);
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counted_base & operator= (counted_base const &);
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// inv: use_count_ <= weak_count_
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long use_count_;
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long weak_count_;
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#if defined(BOOST_HAS_THREADS)
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mutable mutex_type mtx_;
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#endif
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};
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#if defined(BOOST_ENABLE_SHARED_PTR_DEBUG_HOOKS)
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template<class T> void cbi_call_constructor_hook(T * p, checked_deleter<T> const &, int)
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{
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boost::shared_ptr_constructor_hook(p);
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}
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template<class P, class D> void cbi_call_constructor_hook(P const &, D const &, long)
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{
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}
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template<class T> void cbi_call_destructor_hook(T * p, checked_deleter<T> const &, int)
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{
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boost::shared_ptr_destructor_hook(p);
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}
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template<class P, class D> void cbi_call_destructor_hook(P const &, D const &, long)
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{
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}
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#endif
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//
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// Borland's Codeguard trips up over the -Vx- option here:
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//
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#ifdef __CODEGUARD__
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# pragma option push -Vx-
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#endif
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template<class P, class D> class counted_base_impl: public counted_base
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{
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private:
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P ptr; // copy constructor must not throw
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D del; // copy constructor must not throw
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counted_base_impl(counted_base_impl const &);
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counted_base_impl & operator= (counted_base_impl const &);
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typedef counted_base_impl<P, D> this_type;
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public:
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// pre: initial_use_count <= initial_weak_count, d(p) must not throw
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counted_base_impl(P p, D d): ptr(p), del(d)
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{
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#if defined(BOOST_ENABLE_SHARED_PTR_DEBUG_HOOKS)
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detail::cbi_call_constructor_hook(p, d, 0);
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#endif
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}
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virtual void dispose() // nothrow
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{
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#if defined(BOOST_ENABLE_SHARED_PTR_DEBUG_HOOKS)
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detail::cbi_call_destructor_hook(ptr, del, 0);
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#endif
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del(ptr);
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}
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#if defined(BOOST_SP_USE_STD_ALLOCATOR)
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void * operator new(std::size_t)
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{
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return std::allocator<this_type>().allocate(1, static_cast<this_type *>(0));
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}
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void operator delete(void * p)
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{
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std::allocator<this_type>().deallocate(static_cast<this_type *>(p), 1);
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}
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#endif
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};
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class weak_count;
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class shared_count
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{
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private:
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counted_base * pi_;
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friend class weak_count;
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public:
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shared_count(): pi_(0) // nothrow
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{
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}
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template<class P, class D> shared_count(P p, D d): pi_(0)
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{
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#ifndef BOOST_NO_EXCEPTIONS
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try
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{
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pi_ = new counted_base_impl<P, D>(p, d);
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}
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catch(...)
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{
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d(p); // delete p
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throw;
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}
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#else
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pi_ = new counted_base_impl<P, D>(p, d);
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if(pi_ == 0)
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{
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d(p); // delete p
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boost::throw_exception(std::bad_alloc());
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}
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#endif
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}
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#ifndef BOOST_NO_AUTO_PTR
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// auto_ptr<Y> is special cased to provide the strong guarantee
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template<class Y>
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explicit shared_count(std::auto_ptr<Y> & r): pi_(new counted_base_impl< Y *, checked_deleter<Y> >(r.get(), checked_deleter<Y>()))
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{
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r.release();
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}
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#endif
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~shared_count() // nothrow
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{
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if(pi_ != 0) pi_->release();
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}
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shared_count(shared_count const & r): pi_(r.pi_) // nothrow
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{
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if(pi_ != 0) pi_->add_ref();
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}
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explicit shared_count(weak_count const & r); // throws bad_weak_ptr when r.use_count() == 0
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shared_count & operator= (shared_count const & r) // nothrow
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{
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counted_base * tmp = r.pi_;
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if(tmp != 0) tmp->add_ref();
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if(pi_ != 0) pi_->release();
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pi_ = tmp;
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return *this;
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}
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void swap(shared_count & r) // nothrow
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{
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counted_base * tmp = r.pi_;
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r.pi_ = pi_;
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pi_ = tmp;
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}
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long use_count() const // nothrow
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{
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return pi_ != 0? pi_->use_count(): 42; // '42' is an example of 'unspecified'
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}
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bool unique() const // nothrow
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{
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return use_count() == 1;
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}
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friend inline bool operator==(shared_count const & a, shared_count const & b)
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{
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return a.pi_ == b.pi_;
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}
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friend inline bool operator<(shared_count const & a, shared_count const & b)
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{
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return std::less<counted_base *>()(a.pi_, b.pi_);
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}
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};
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#ifdef __CODEGUARD__
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# pragma option pop
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#endif
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class weak_count
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{
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private:
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counted_base * pi_;
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friend class shared_count;
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public:
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weak_count(): pi_(0) // nothrow
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{
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}
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weak_count(shared_count const & r): pi_(r.pi_) // nothrow
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{
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if(pi_ != 0) pi_->weak_add_ref();
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}
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weak_count(weak_count const & r): pi_(r.pi_) // nothrow
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{
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if(pi_ != 0) pi_->weak_add_ref();
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}
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~weak_count() // nothrow
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{
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if(pi_ != 0) pi_->weak_release();
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}
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weak_count & operator= (shared_count const & r) // nothrow
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{
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counted_base * tmp = r.pi_;
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if(tmp != 0) tmp->weak_add_ref();
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if(pi_ != 0) pi_->weak_release();
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pi_ = tmp;
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return *this;
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}
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weak_count & operator= (weak_count const & r) // nothrow
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{
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counted_base * tmp = r.pi_;
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if(tmp != 0) tmp->weak_add_ref();
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if(pi_ != 0) pi_->weak_release();
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pi_ = tmp;
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return *this;
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}
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void swap(weak_count & r) // nothrow
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{
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counted_base * tmp = r.pi_;
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r.pi_ = pi_;
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pi_ = tmp;
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}
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long use_count() const // nothrow
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{
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return pi_ != 0? pi_->use_count(): 804; // '804' is an example of 'unspecified'
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}
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friend inline bool operator==(weak_count const & a, weak_count const & b)
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{
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return a.pi_ == b.pi_;
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}
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friend inline bool operator<(weak_count const & a, weak_count const & b)
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{
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return std::less<counted_base *>()(a.pi_, b.pi_);
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}
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};
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inline shared_count::shared_count(weak_count const & r): pi_(r.pi_)
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{
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if(pi_ != 0) pi_->add_ref();
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}
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} // namespace detail
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} // namespace boost
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#ifdef __BORLANDC__
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# pragma warn .8027 // Functions containing try are not expanded inline
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# pragma warn .8026 // Functions with excep. spec. are not expanded inline
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#endif
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#endif // #ifndef BOOST_DETAIL_SHARED_COUNT_HPP_INCLUDED
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