| #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 detail::sp_enable_if_convertible<Y,T>::type = 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 detail::sp_enable_if_convertible<Y,T>::type = detail::sp_empty() ) |
| |
| #else |
| |
| weak_ptr( weak_ptr<Y> && r ) |
| |
| #endif |
| : px(r.lock().get()), pn(std::move(r.pn)) // never throws |
| { |
| r.px = 0; |
| } |
| |
| // for better efficiency in the T == Y case |
| weak_ptr( weak_ptr && r ): px( r.px ), pn(std::move(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( std::move( r ) ).swap( *this ); |
| return *this; |
| } |
| |
| |
| #endif |
| |
| template<class Y> |
| #if !defined( BOOST_SP_NO_SP_CONVERTIBLE ) |
| |
| weak_ptr( shared_ptr<Y> const & r, typename detail::sp_enable_if_convertible<Y,T>::type = 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( std::move( 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 |