mirror of
https://github.com/boostorg/smart_ptr.git
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434 lines
10 KiB
C++
434 lines
10 KiB
C++
#ifndef BOOST_SHARED_PTR_HPP_INCLUDED
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#define BOOST_SHARED_PTR_HPP_INCLUDED
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//
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// shared_ptr.hpp
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//
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// (C) Copyright Greg Colvin and Beman Dawes 1998, 1999.
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// Copyright (c) 2001, 2002, 2003 Peter Dimov
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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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// See http://www.boost.org/libs/smart_ptr/shared_ptr.htm for documentation.
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//
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#include <boost/config.hpp> // for broken compiler workarounds
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#if defined(BOOST_NO_MEMBER_TEMPLATES) && !defined(BOOST_MSVC6_MEMBER_TEMPLATES)
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#include <boost/detail/shared_ptr_nmt.hpp>
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#else
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#include <boost/assert.hpp>
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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/shared_count.hpp>
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#include <boost/detail/workaround.hpp>
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#include <memory> // for std::auto_ptr
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#include <algorithm> // for std::swap
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#include <functional> // for std::less
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#include <typeinfo> // for std::bad_cast
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#include <iosfwd> // for std::basic_ostream
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#ifdef BOOST_MSVC // moved here to work around VC++ compiler crash
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# pragma warning(push)
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# pragma warning(disable:4284) // odd return type for operator->
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#endif
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namespace boost
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{
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template<class T> class weak_ptr;
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template<class T> class enable_shared_from_this;
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namespace detail
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{
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struct static_cast_tag {};
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struct dynamic_cast_tag {};
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struct polymorphic_cast_tag {};
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template<class T> struct shared_ptr_traits
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{
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typedef T & reference;
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};
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template<> struct shared_ptr_traits<void>
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{
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typedef void reference;
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};
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#if !defined(BOOST_NO_CV_VOID_SPECIALIZATIONS)
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template<> struct shared_ptr_traits<void const>
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{
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typedef void reference;
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};
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#endif
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// enable_shared_from_this support
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template<class T, class Y> void sp_enable_shared_from_this(boost::enable_shared_from_this<T> * pe, Y * px, shared_count const & pn)
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{
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if(pe != 0) pe->_internal_weak_this._internal_assign(px, pn);
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}
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inline void sp_enable_shared_from_this(void const *, void const *, shared_count const &)
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{
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}
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} // namespace detail
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//
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// shared_ptr
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//
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// An enhanced relative of scoped_ptr with reference counted copy semantics.
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// The object pointed to is deleted when the last shared_ptr pointing to it
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// is destroyed or reset.
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//
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template<class T> class shared_ptr
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{
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private:
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// Borland 5.5.1 specific workaround
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typedef shared_ptr<T> this_type;
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public:
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typedef T element_type;
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typedef T value_type;
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typedef T * pointer;
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typedef typename detail::shared_ptr_traits<T>::reference reference;
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shared_ptr(): px(0), pn() // never throws in 1.30+
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{
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}
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template<class Y>
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explicit shared_ptr(Y * p): px(p), pn(p, checked_deleter<Y>()) // Y must be complete
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{
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detail::sp_enable_shared_from_this(p, p, pn);
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}
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//
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// Requirements: D's copy constructor must not throw
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//
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// shared_ptr will release p by calling d(p)
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//
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template<class Y, class D> shared_ptr(Y * p, D d): px(p), pn(p, d)
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{
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detail::sp_enable_shared_from_this(p, p, pn);
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}
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// generated copy constructor, assignment, destructor are fine...
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// except on Borland C++ 5.5.1 (and 5.6)
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#if defined(__BORLANDC__) && (__BORLANDC__ <= 0x561)
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shared_ptr & operator=(shared_ptr const & r) // never throws
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{
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px = r.px;
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pn = r.pn; // shared_count::op= doesn't throw
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return *this;
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}
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#endif
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template<class Y>
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explicit shared_ptr(weak_ptr<Y> const & r): pn(r.pn) // may throw
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{
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// it is now safe to copy r.px, as pn(r.pn) did not throw
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px = r.px;
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}
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template<class Y>
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shared_ptr(shared_ptr<Y> const & r): px(r.px), pn(r.pn) // never throws
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{
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}
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template<class Y>
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shared_ptr(shared_ptr<Y> const & r, detail::static_cast_tag): px(static_cast<element_type *>(r.px)), pn(r.pn)
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{
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}
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template<class Y>
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shared_ptr(shared_ptr<Y> const & r, detail::dynamic_cast_tag): px(dynamic_cast<element_type *>(r.px)), pn(r.pn)
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{
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if(px == 0) // need to allocate new counter -- the cast failed
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{
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pn = detail::shared_count();
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}
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}
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template<class Y>
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shared_ptr(shared_ptr<Y> const & r, detail::polymorphic_cast_tag): px(dynamic_cast<element_type *>(r.px)), pn(r.pn)
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{
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if(px == 0)
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{
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boost::throw_exception(std::bad_cast());
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}
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}
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#ifndef BOOST_NO_AUTO_PTR
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template<class Y>
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explicit shared_ptr(std::auto_ptr<Y> & r): px(r.get()), pn()
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{
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Y * tmp = r.get();
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pn = detail::shared_count(r);
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detail::sp_enable_shared_from_this(tmp, tmp, pn);
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}
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#endif
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#if !defined(BOOST_MSVC) || (BOOST_MSVC > 1200)
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template<class Y>
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shared_ptr & operator=(shared_ptr<Y> const & r) // never throws
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{
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px = r.px;
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pn = r.pn; // shared_count::op= doesn't throw
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return *this;
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}
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#endif
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#ifndef BOOST_NO_AUTO_PTR
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template<class Y>
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shared_ptr & operator=(std::auto_ptr<Y> & r)
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{
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this_type(r).swap(*this);
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return *this;
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}
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#endif
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void reset() // never throws in 1.30+
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{
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this_type().swap(*this);
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}
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template<class Y> void reset(Y * p) // Y must be complete
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{
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BOOST_ASSERT(p == 0 || p != px); // catch self-reset errors
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this_type(p).swap(*this);
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}
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template<class Y, class D> void reset(Y * p, D d)
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{
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this_type(p, d).swap(*this);
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}
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reference operator* () const // never throws
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{
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BOOST_ASSERT(px != 0);
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return *px;
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}
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T * operator-> () const // never throws
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{
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BOOST_ASSERT(px != 0);
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return px;
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}
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T * get() const // never throws
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{
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return px;
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}
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// implicit conversion to "bool"
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typedef T * (this_type::*unspecified_bool_type)() const;
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operator unspecified_bool_type() const // never throws
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{
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return px == 0? 0: &this_type::get;
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}
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// operator! is redundant, but some compilers need it
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bool operator! () const // never throws
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{
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return px == 0;
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}
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bool unique() const // never throws
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{
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return pn.unique();
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}
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long use_count() const // never throws
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{
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return pn.use_count();
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}
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void swap(shared_ptr<T> & other) // never throws
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{
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std::swap(px, other.px);
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pn.swap(other.pn);
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}
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template<class Y> bool _internal_less(shared_ptr<Y> const & rhs) const
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{
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return pn < rhs.pn;
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}
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void * _internal_get_deleter(std::type_info const & ti) const
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{
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return pn.get_deleter(ti);
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}
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// Tasteless as this may seem, making all members public allows member templates
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// to work in the absence of member template friends. (Matthew Langston)
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#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
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private:
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template<class Y> friend class shared_ptr;
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template<class Y> friend class weak_ptr;
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#endif
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T * px; // contained pointer
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detail::shared_count pn; // reference counter
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}; // shared_ptr
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template<class T, class U> inline bool operator==(shared_ptr<T> const & a, shared_ptr<U> const & b)
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{
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return a.get() == b.get();
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}
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template<class T, class U> inline bool operator!=(shared_ptr<T> const & a, shared_ptr<U> const & b)
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{
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return a.get() != b.get();
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}
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#if __GNUC__ == 2 && __GNUC_MINOR__ <= 96
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// Resolve the ambiguity between our op!= and the one in rel_ops
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template<class T> inline bool operator!=(shared_ptr<T> const & a, shared_ptr<T> const & b)
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{
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return a.get() != b.get();
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}
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#endif
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template<class T, class U> inline bool operator<(shared_ptr<T> const & a, shared_ptr<U> const & b)
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{
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return a._internal_less(b);
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}
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template<class T> inline void swap(shared_ptr<T> & a, shared_ptr<T> & b)
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{
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a.swap(b);
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}
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template<class T, class U> shared_ptr<T> static_pointer_cast(shared_ptr<U> const & r)
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{
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return shared_ptr<T>(r, detail::static_cast_tag());
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}
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template<class T, class U> shared_ptr<T> dynamic_pointer_cast(shared_ptr<U> const & r)
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{
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return shared_ptr<T>(r, detail::dynamic_cast_tag());
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}
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// shared_*_cast names are deprecated. Use *_pointer_cast instead.
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template<class T, class U> shared_ptr<T> shared_static_cast(shared_ptr<U> const & r)
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{
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return shared_ptr<T>(r, detail::static_cast_tag());
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}
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template<class T, class U> shared_ptr<T> shared_dynamic_cast(shared_ptr<U> const & r)
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{
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return shared_ptr<T>(r, detail::dynamic_cast_tag());
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}
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template<class T, class U> shared_ptr<T> shared_polymorphic_cast(shared_ptr<U> const & r)
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{
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return shared_ptr<T>(r, detail::polymorphic_cast_tag());
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}
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template<class T, class U> shared_ptr<T> shared_polymorphic_downcast(shared_ptr<U> const & r)
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{
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BOOST_ASSERT(dynamic_cast<T *>(r.get()) == r.get());
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return shared_static_cast<T>(r);
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}
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// get_pointer() enables boost::mem_fn to recognize shared_ptr
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template<class T> inline T * get_pointer(shared_ptr<T> const & p)
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{
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return p.get();
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}
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// operator<<
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#if defined(__GNUC__) && (__GNUC__ < 3)
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template<class Y> std::ostream & operator<< (std::ostream & os, shared_ptr<Y> const & p)
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{
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os << p.get();
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return os;
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}
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#else
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# if BOOST_WORKAROUND(BOOST_MSVC, <= 1200 && __SGI_STL_PORT)
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// MSVC6 has problems finding std::basic_ostream through the using declaration in namespace _STL
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using std::basic_ostream;
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template<class E, class T, class Y> basic_ostream<E, T> & operator<< (basic_ostream<E, T> & os, shared_ptr<Y> const & p)
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# else
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template<class E, class T, class Y> std::basic_ostream<E, T> & operator<< (std::basic_ostream<E, T> & os, shared_ptr<Y> const & p)
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# endif
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{
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os << p.get();
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return os;
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}
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#endif
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// get_deleter (experimental)
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#if defined(__GNUC__) && (__GNUC__ < 3)
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// g++ 2.9x doesn't allow static_cast<X const *>(void *)
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template<class D, class T> D * get_deleter(shared_ptr<T> const & p)
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{
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void const * q = p._internal_get_deleter(typeid(D));
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return const_cast<D *>(static_cast<D const *>(q));
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}
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#else
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template<class D, class T> D * get_deleter(shared_ptr<T> const & p)
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{
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return static_cast<D *>(p._internal_get_deleter(typeid(D)));
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}
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#endif
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} // namespace boost
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#ifdef BOOST_MSVC
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# pragma warning(pop)
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#endif
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#endif // #if defined(BOOST_NO_MEMBER_TEMPLATES) && !defined(BOOST_MSVC6_MEMBER_TEMPLATES)
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#endif // #ifndef BOOST_SHARED_PTR_HPP_INCLUDED
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