#ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED | |
#define BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED | |
// | |
// weak_ptr.hpp | |
// | |
// Copyright (c) 2001, 2002, 2003 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) | |
// | |
// See http://www.boost.org/libs/smart_ptr/weak_ptr.htm for documentation. | |
// | |
#include <memory> // boost.TR1 include order fix | |
#include <boost/smart_ptr/detail/shared_count.hpp> | |
#include <boost/smart_ptr/shared_ptr.hpp> | |
#ifdef BOOST_MSVC // moved here to work around VC++ compiler crash | |
# pragma warning(push) | |
# pragma warning(disable:4284) // odd return type for operator-> | |
#endif | |
namespace boost | |
{ | |
template<class T> class weak_ptr | |
{ | |
private: | |
// Borland 5.5.1 specific workarounds | |
typedef weak_ptr<T> this_type; | |
public: | |
typedef T element_type; | |
weak_ptr(): px(0), pn() // never throws in 1.30+ | |
{ | |
} | |
// generated copy constructor, assignment, destructor are fine | |
// | |
// The "obvious" converting constructor implementation: | |
// | |
// template<class Y> | |
// weak_ptr(weak_ptr<Y> const & r): px(r.px), pn(r.pn) // never throws | |
// { | |
// } | |
// | |
// has a serious problem. | |
// | |
// r.px may already have been invalidated. The px(r.px) | |
// conversion may require access to *r.px (virtual inheritance). | |
// | |
// It is not possible to avoid spurious access violations since | |
// in multithreaded programs r.px may be invalidated at any point. | |
// | |
template<class Y> | |
#if !defined( BOOST_SP_NO_SP_CONVERTIBLE ) | |
weak_ptr( weak_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() ) | |
#else | |
weak_ptr( weak_ptr<Y> const & r ) | |
#endif | |
: px(r.lock().get()), pn(r.pn) // never throws | |
{ | |
} | |
#if defined( BOOST_HAS_RVALUE_REFS ) | |
template<class Y> | |
#if !defined( BOOST_SP_NO_SP_CONVERTIBLE ) | |
weak_ptr( weak_ptr<Y> && r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() ) | |
#else | |
weak_ptr( weak_ptr<Y> && r ) | |
#endif | |
: px( r.lock().get() ), pn( static_cast< boost::detail::weak_count && >( r.pn ) ) // never throws | |
{ | |
r.px = 0; | |
} | |
// for better efficiency in the T == Y case | |
weak_ptr( weak_ptr && r ): px( r.px ), pn( static_cast< boost::detail::weak_count && >( r.pn ) ) // never throws | |
{ | |
r.px = 0; | |
} | |
// for better efficiency in the T == Y case | |
weak_ptr & operator=( weak_ptr && r ) // never throws | |
{ | |
this_type( static_cast< weak_ptr && >( r ) ).swap( *this ); | |
return *this; | |
} | |
#endif | |
template<class Y> | |
#if !defined( BOOST_SP_NO_SP_CONVERTIBLE ) | |
weak_ptr( shared_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() ) | |
#else | |
weak_ptr( shared_ptr<Y> const & r ) | |
#endif | |
: px( r.px ), pn( r.pn ) // never throws | |
{ | |
} | |
#if !defined(BOOST_MSVC) || (BOOST_MSVC >= 1300) | |
template<class Y> | |
weak_ptr & operator=(weak_ptr<Y> const & r) // never throws | |
{ | |
px = r.lock().get(); | |
pn = r.pn; | |
return *this; | |
} | |
#if defined( BOOST_HAS_RVALUE_REFS ) | |
template<class Y> | |
weak_ptr & operator=( weak_ptr<Y> && r ) | |
{ | |
this_type( static_cast< weak_ptr<Y> && >( r ) ).swap( *this ); | |
return *this; | |
} | |
#endif | |
template<class Y> | |
weak_ptr & operator=(shared_ptr<Y> const & r) // never throws | |
{ | |
px = r.px; | |
pn = r.pn; | |
return *this; | |
} | |
#endif | |
shared_ptr<T> lock() const // never throws | |
{ | |
return shared_ptr<element_type>( *this, boost::detail::sp_nothrow_tag() ); | |
} | |
long use_count() const // never throws | |
{ | |
return pn.use_count(); | |
} | |
bool expired() const // never throws | |
{ | |
return pn.use_count() == 0; | |
} | |
bool _empty() const // extension, not in std::weak_ptr | |
{ | |
return pn.empty(); | |
} | |
void reset() // never throws in 1.30+ | |
{ | |
this_type().swap(*this); | |
} | |
void swap(this_type & other) // never throws | |
{ | |
std::swap(px, other.px); | |
pn.swap(other.pn); | |
} | |
void _internal_assign(T * px2, boost::detail::shared_count const & pn2) | |
{ | |
px = px2; | |
pn = pn2; | |
} | |
template<class Y> bool _internal_less(weak_ptr<Y> const & rhs) const | |
{ | |
return pn < rhs.pn; | |
} | |
// Tasteless as this may seem, making all members public allows member templates | |
// to work in the absence of member template friends. (Matthew Langston) | |
#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS | |
private: | |
template<class Y> friend class weak_ptr; | |
template<class Y> friend class shared_ptr; | |
#endif | |
T * px; // contained pointer | |
boost::detail::weak_count pn; // reference counter | |
}; // weak_ptr | |
template<class T, class U> inline bool operator<(weak_ptr<T> const & a, weak_ptr<U> const & b) | |
{ | |
return a._internal_less(b); | |
} | |
template<class T> void swap(weak_ptr<T> & a, weak_ptr<T> & b) | |
{ | |
a.swap(b); | |
} | |
} // namespace boost | |
#ifdef BOOST_MSVC | |
# pragma warning(pop) | |
#endif | |
#endif // #ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED |