Chris@16: #ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED
Chris@16: #define BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED
Chris@16: 
Chris@16: //
Chris@16: //  weak_ptr.hpp
Chris@16: //
Chris@16: //  Copyright (c) 2001, 2002, 2003 Peter Dimov
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: //  See http://www.boost.org/libs/smart_ptr/weak_ptr.htm for documentation.
Chris@16: //
Chris@16: 
Chris@16: #include <memory> // boost.TR1 include order fix
Chris@16: #include <boost/smart_ptr/detail/shared_count.hpp>
Chris@16: #include <boost/smart_ptr/shared_ptr.hpp>
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16: 
Chris@16: template<class T> class weak_ptr
Chris@16: {
Chris@16: private:
Chris@16: 
Chris@16:     // Borland 5.5.1 specific workarounds
Chris@16:     typedef weak_ptr<T> this_type;
Chris@16: 
Chris@16: public:
Chris@16: 
Chris@16:     typedef typename boost::detail::sp_element< T >::type element_type;
Chris@16: 
Chris@16:     weak_ptr() BOOST_NOEXCEPT : px(0), pn() // never throws in 1.30+
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16: //  generated copy constructor, assignment, destructor are fine...
Chris@16: 
Chris@16: #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
Chris@16: 
Chris@16: // ... except in C++0x, move disables the implicit copy
Chris@16: 
Chris@16:     weak_ptr( weak_ptr const & r ) BOOST_NOEXCEPT : px( r.px ), pn( r.pn )
Chris@16:     {
Chris@16:     }
Chris@16: 
Chris@16:     weak_ptr & operator=( weak_ptr const & r ) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         px = r.px;
Chris@16:         pn = r.pn;
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16: //
Chris@16: //  The "obvious" converting constructor implementation:
Chris@16: //
Chris@16: //  template<class Y>
Chris@16: //  weak_ptr(weak_ptr<Y> const & r): px(r.px), pn(r.pn) // never throws
Chris@16: //  {
Chris@16: //  }
Chris@16: //
Chris@16: //  has a serious problem.
Chris@16: //
Chris@16: //  r.px may already have been invalidated. The px(r.px)
Chris@16: //  conversion may require access to *r.px (virtual inheritance).
Chris@16: //
Chris@16: //  It is not possible to avoid spurious access violations since
Chris@16: //  in multithreaded programs r.px may be invalidated at any point.
Chris@16: //
Chris@16: 
Chris@16:     template<class Y>
Chris@16: #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
Chris@16: 
Chris@16:     weak_ptr( weak_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16:     weak_ptr( weak_ptr<Y> const & r )
Chris@16: 
Chris@16: #endif
Chris@16:     BOOST_NOEXCEPT : px(r.lock().get()), pn(r.pn)
Chris@16:     {
Chris@16:         boost::detail::sp_assert_convertible< Y, T >();
Chris@16:     }
Chris@16: 
Chris@16: #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
Chris@16: 
Chris@16:     template<class Y>
Chris@16: #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
Chris@16: 
Chris@16:     weak_ptr( weak_ptr<Y> && r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16:     weak_ptr( weak_ptr<Y> && r )
Chris@16: 
Chris@16: #endif
Chris@16:     BOOST_NOEXCEPT : px( r.lock().get() ), pn( static_cast< boost::detail::weak_count && >( r.pn ) )
Chris@16:     {
Chris@16:         boost::detail::sp_assert_convertible< Y, T >();
Chris@16:         r.px = 0;
Chris@16:     }
Chris@16: 
Chris@16:     // for better efficiency in the T == Y case
Chris@16:     weak_ptr( weak_ptr && r )
Chris@16:     BOOST_NOEXCEPT : px( r.px ), pn( static_cast< boost::detail::weak_count && >( r.pn ) )
Chris@16:     {
Chris@16:         r.px = 0;
Chris@16:     }
Chris@16: 
Chris@16:     // for better efficiency in the T == Y case
Chris@16:     weak_ptr & operator=( weak_ptr && r ) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         this_type( static_cast< weak_ptr && >( r ) ).swap( *this );
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16:     template<class Y>
Chris@16: #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
Chris@16: 
Chris@16:     weak_ptr( shared_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
Chris@16: 
Chris@16: #else
Chris@16: 
Chris@16:     weak_ptr( shared_ptr<Y> const & r )
Chris@16: 
Chris@16: #endif
Chris@16:     BOOST_NOEXCEPT : px( r.px ), pn( r.pn )
Chris@16:     {
Chris@16:         boost::detail::sp_assert_convertible< Y, T >();
Chris@16:     }
Chris@16: 
Chris@16: #if !defined(BOOST_MSVC) || (BOOST_MSVC >= 1300)
Chris@16: 
Chris@16:     template<class Y>
Chris@16:     weak_ptr & operator=( weak_ptr<Y> const & r ) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         boost::detail::sp_assert_convertible< Y, T >();
Chris@16: 
Chris@16:         px = r.lock().get();
Chris@16:         pn = r.pn;
Chris@16: 
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16: #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
Chris@16: 
Chris@16:     template<class Y>
Chris@16:     weak_ptr & operator=( weak_ptr<Y> && r ) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         this_type( static_cast< weak_ptr<Y> && >( r ) ).swap( *this );
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16:     template<class Y>
Chris@16:     weak_ptr & operator=( shared_ptr<Y> const & r ) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         boost::detail::sp_assert_convertible< Y, T >();
Chris@16: 
Chris@16:         px = r.px;
Chris@16:         pn = r.pn;
Chris@16: 
Chris@16:         return *this;
Chris@16:     }
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16:     shared_ptr<T> lock() const BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         return shared_ptr<T>( *this, boost::detail::sp_nothrow_tag() );
Chris@16:     }
Chris@16: 
Chris@16:     long use_count() const BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         return pn.use_count();
Chris@16:     }
Chris@16: 
Chris@16:     bool expired() const BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         return pn.use_count() == 0;
Chris@16:     }
Chris@16: 
Chris@16:     bool _empty() const // extension, not in std::weak_ptr
Chris@16:     {
Chris@16:         return pn.empty();
Chris@16:     }
Chris@16: 
Chris@16:     void reset() BOOST_NOEXCEPT // never throws in 1.30+
Chris@16:     {
Chris@16:         this_type().swap(*this);
Chris@16:     }
Chris@16: 
Chris@16:     void swap(this_type & other) BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         std::swap(px, other.px);
Chris@16:         pn.swap(other.pn);
Chris@16:     }
Chris@16: 
Chris@16:     template<typename Y>
Chris@16:     void _internal_aliasing_assign(weak_ptr<Y> const & r, element_type * px2)
Chris@16:     {
Chris@16:         px = px2;
Chris@16:         pn = r.pn;
Chris@16:     }
Chris@16: 
Chris@16:     template<class Y> bool owner_before( weak_ptr<Y> const & rhs ) const BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         return pn < rhs.pn;
Chris@16:     }
Chris@16: 
Chris@16:     template<class Y> bool owner_before( shared_ptr<Y> const & rhs ) const BOOST_NOEXCEPT
Chris@16:     {
Chris@16:         return pn < rhs.pn;
Chris@16:     }
Chris@16: 
Chris@16: // Tasteless as this may seem, making all members public allows member templates
Chris@16: // to work in the absence of member template friends. (Matthew Langston)
Chris@16: 
Chris@16: #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
Chris@16: 
Chris@16: private:
Chris@16: 
Chris@16:     template<class Y> friend class weak_ptr;
Chris@16:     template<class Y> friend class shared_ptr;
Chris@16: 
Chris@16: #endif
Chris@16: 
Chris@16:     element_type * px;            // contained pointer
Chris@16:     boost::detail::weak_count pn; // reference counter
Chris@16: 
Chris@16: };  // weak_ptr
Chris@16: 
Chris@16: template<class T, class U> inline bool operator<(weak_ptr<T> const & a, weak_ptr<U> const & b) BOOST_NOEXCEPT
Chris@16: {
Chris@16:     return a.owner_before( b );
Chris@16: }
Chris@16: 
Chris@16: template<class T> void swap(weak_ptr<T> & a, weak_ptr<T> & b) BOOST_NOEXCEPT
Chris@16: {
Chris@16:     a.swap(b);
Chris@16: }
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif  // #ifndef BOOST_SMART_PTR_WEAK_PTR_HPP_INCLUDED