text: #ifndef BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED
  #define BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED
  
  //
  //  shared_ptr.hpp
  //
  //  (C) Copyright Greg Colvin and Beman Dawes 1998, 1999.
  //  Copyright (c) 2001-2008 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/shared_ptr.htm for documentation.
  //
  
  #include <boost/config.hpp>   // for broken compiler workarounds
  
  // In order to avoid circular dependencies with Boost.TR1
  // we make sure that our include of <memory> doesn't try to
  // pull in the TR1 headers: that's why we use this header 
  // rather than including <memory> directly:
  #include <boost/config/no_tr1/memory.hpp>  // std::auto_ptr
  
  #include <boost/assert.hpp>
  #include <boost/checked_delete.hpp>
  #include <boost/throw_exception.hpp>
  #include <boost/smart_ptr/detail/shared_count.hpp>
  #include <boost/detail/workaround.hpp>
  #include <boost/smart_ptr/detail/sp_convertible.hpp>
  #include <boost/smart_ptr/detail/sp_nullptr_t.hpp>
  
  #if !defined(BOOST_SP_NO_ATOMIC_ACCESS)
  #include <boost/smart_ptr/detail/spinlock_pool.hpp>
  #endif
  
  #include <algorithm>            // for std::swap
  #include <functional>           // for std::less
  #include <typeinfo>             // for std::bad_cast
  #include <cstddef>              // for std::size_t
  
  #if !defined(BOOST_NO_IOSTREAM)
  #if !defined(BOOST_NO_IOSFWD)
  #include <iosfwd>               // for std::basic_ostream
  #else
  #include <ostream>
  #endif
  #endif
  
  namespace boost
  {
  
  template<class T> class shared_ptr;
  template<class T> class weak_ptr;
  template<class T> class enable_shared_from_this;
  class enable_shared_from_raw;
  
  namespace detail
  {
  
  // sp_element, element_type
  
  template< class T > struct sp_element
  {
      typedef T type;
  };
  
  #if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  template< class T > struct sp_element< T[] >
  {
      typedef T type;
  };
  
  #if !defined( __BORLANDC__ ) || !BOOST_WORKAROUND( __BORLANDC__, < 0x600 )
  
  template< class T, std::size_t N > struct sp_element< T[N] >
  {
      typedef T type;
  };
  
  #endif
  
  #endif // !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  // sp_dereference, return type of operator*
  
  template< class T > struct sp_dereference
  {
      typedef T & type;
  };
  
  template<> struct sp_dereference< void >
  {
      typedef void type;
  };
  
  #if !defined(BOOST_NO_CV_VOID_SPECIALIZATIONS)
  
  template<> struct sp_dereference< void const >
  {
      typedef void type;
  };
  
  template<> struct sp_dereference< void volatile >
  {
      typedef void type;
  };
  
  template<> struct sp_dereference< void const volatile >
  {
      typedef void type;
  };
  
  #endif // !defined(BOOST_NO_CV_VOID_SPECIALIZATIONS)
  
  #if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  template< class T > struct sp_dereference< T[] >
  {
      typedef void type;
  };
  
  #if !defined( __BORLANDC__ ) || !BOOST_WORKAROUND( __BORLANDC__, < 0x600 )
  
  template< class T, std::size_t N > struct sp_dereference< T[N] >
  {
      typedef void type;
  };
  
  #endif
  
  #endif // !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  // sp_member_access, return type of operator->
  
  template< class T > struct sp_member_access
  {
      typedef T * type;
  };
  
  #if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  template< class T > struct sp_member_access< T[] >
  {
      typedef void type;
  };
  
  #if !defined( __BORLANDC__ ) || !BOOST_WORKAROUND( __BORLANDC__, < 0x600 )
  
  template< class T, std::size_t N > struct sp_member_access< T[N] >
  {
      typedef void type;
  };
  
  #endif
  
  #endif // !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  // sp_array_access, return type of operator[]
  
  template< class T > struct sp_array_access
  {
      typedef void type;
  };
  
  #if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  template< class T > struct sp_array_access< T[] >
  {
      typedef T & type;
  };
  
  #if !defined( __BORLANDC__ ) || !BOOST_WORKAROUND( __BORLANDC__, < 0x600 )
  
  template< class T, std::size_t N > struct sp_array_access< T[N] >
  {
      typedef T & type;
  };
  
  #endif
  
  #endif // !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  // sp_extent, for operator[] index check
  
  template< class T > struct sp_extent
  {
      enum _vt { value = 0 };
  };
  
  #if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  template< class T, std::size_t N > struct sp_extent< T[N] >
  {
      enum _vt { value = N };
  };
  
  #endif // !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  // enable_shared_from_this support
  
  template< class X, class Y, class T > inline void sp_enable_shared_from_this( boost::shared_ptr<X> const * ppx, Y const * py, boost::enable_shared_from_this< T > const * pe )
  {
      if( pe != 0 )
      {
          pe->_internal_accept_owner( ppx, const_cast< Y* >( py ) );
      }
  }
  
  template< class X, class Y > inline void sp_enable_shared_from_this( boost::shared_ptr<X> * ppx, Y const * py, boost::enable_shared_from_raw const * pe );
  
  #ifdef _MANAGED
  
  // Avoid C4793, ... causes native code generation
  
  struct sp_any_pointer
  {
      template<class T> sp_any_pointer( T* ) {}
  };
  
  inline void sp_enable_shared_from_this( sp_any_pointer, sp_any_pointer, sp_any_pointer )
  {
  }
  
  #else // _MANAGED
  
  inline void sp_enable_shared_from_this( ... )
  {
  }
  
  #endif // _MANAGED
  
  #if !defined( BOOST_NO_SFINAE ) && !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined( BOOST_NO_AUTO_PTR )
  
  // rvalue auto_ptr support based on a technique by Dave Abrahams
  
  template< class T, class R > struct sp_enable_if_auto_ptr
  {
  };
  
  template< class T, class R > struct sp_enable_if_auto_ptr< std::auto_ptr< T >, R >
  {
      typedef R type;
  }; 
  
  #endif
  
  // sp_assert_convertible
  
  template< class Y, class T > inline void sp_assert_convertible()
  {
  #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
  
      // static_assert( sp_convertible< Y, T >::value );
      typedef char tmp[ sp_convertible< Y, T >::value? 1: -1 ];
      (void)sizeof( tmp );
  
  #else
  
      T* p = static_cast< Y* >( 0 );
      (void)p;
  
  #endif
  }
  
  // pointer constructor helper
  
  template< class T, class Y > inline void sp_pointer_construct( boost::shared_ptr< T > * ppx, Y * p, boost::detail::shared_count & pn )
  {
      boost::detail::shared_count( p ).swap( pn );
      boost::detail::sp_enable_shared_from_this( ppx, p, p );
  }
  
  #if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  template< class T, class Y > inline void sp_pointer_construct( boost::shared_ptr< T[] > * /*ppx*/, Y * p, boost::detail::shared_count & pn )
  {
      sp_assert_convertible< Y[], T[] >();
      boost::detail::shared_count( p, boost::checked_array_deleter< T >() ).swap( pn );
  }
  
  template< class T, std::size_t N, class Y > inline void sp_pointer_construct( boost::shared_ptr< T[N] > * /*ppx*/, Y * p, boost::detail::shared_count & pn )
  {
      sp_assert_convertible< Y[N], T[N] >();
      boost::detail::shared_count( p, boost::checked_array_deleter< T >() ).swap( pn );
  }
  
  #endif // !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  // deleter constructor helper
  
  template< class T, class Y > inline void sp_deleter_construct( boost::shared_ptr< T > * ppx, Y * p )
  {
      boost::detail::sp_enable_shared_from_this( ppx, p, p );
  }
  
  #if !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  template< class T, class Y > inline void sp_deleter_construct( boost::shared_ptr< T[] > * /*ppx*/, Y * /*p*/ )
  {
      sp_assert_convertible< Y[], T[] >();
  }
  
  template< class T, std::size_t N, class Y > inline void sp_deleter_construct( boost::shared_ptr< T[N] > * /*ppx*/, Y * /*p*/ )
  {
      sp_assert_convertible< Y[N], T[N] >();
  }
  
  #endif // !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
  } // namespace detail
  
  
  //
  //  shared_ptr
  //
  //  An enhanced relative of scoped_ptr with reference counted copy semantics.
  //  The object pointed to is deleted when the last shared_ptr pointing to it
  //  is destroyed or reset.
  //
  
  template<class T> class shared_ptr
  {
  private:
  
      // Borland 5.5.1 specific workaround
      typedef shared_ptr<T> this_type;
  
  public:
  
      typedef typename boost::detail::sp_element< T >::type element_type;
  
      shared_ptr() BOOST_NOEXCEPT : px( 0 ), pn() // never throws in 1.30+
      {
      }
  
  #if !defined( BOOST_NO_CXX11_NULLPTR )
  
      shared_ptr( boost::detail::sp_nullptr_t ) BOOST_NOEXCEPT : px( 0 ), pn() // never throws
      {
      }
  
  #endif
  
      template<class Y>
      explicit shared_ptr( Y * p ): px( p ), pn() // Y must be complete
      {
          boost::detail::sp_pointer_construct( this, p, pn );
      }
  
      //
      // Requirements: D's copy constructor must not throw
      //
      // shared_ptr will release p by calling d(p)
      //
  
      template<class Y, class D> shared_ptr( Y * p, D d ): px( p ), pn( p, d )
      {
          boost::detail::sp_deleter_construct( this, p );
      }
  
  #if !defined( BOOST_NO_CXX11_NULLPTR )
  
      template<class D> shared_ptr( boost::detail::sp_nullptr_t p, D d ): px( p ), pn( p, d )
      {
      }
  
  #endif
  
      // As above, but with allocator. A's copy constructor shall not throw.
  
      template<class Y, class D, class A> shared_ptr( Y * p, D d, A a ): px( p ), pn( p, d, a )
      {
          boost::detail::sp_deleter_construct( this, p );
      }
  
  #if !defined( BOOST_NO_CXX11_NULLPTR )
  
      template<class D, class A> shared_ptr( boost::detail::sp_nullptr_t p, D d, A a ): px( p ), pn( p, d, a )
      {
      }
  
  #endif
  
  //  generated copy constructor, destructor are fine...
  
  #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  
  // ... except in C++0x, move disables the implicit copy
  
      shared_ptr( shared_ptr const & r ) BOOST_NOEXCEPT : px( r.px ), pn( r.pn )
      {
      }
  
  #endif
  
      template<class Y>
      explicit shared_ptr( weak_ptr<Y> const & r ): pn( r.pn ) // may throw
      {
          boost::detail::sp_assert_convertible< Y, T >();
  
          // it is now safe to copy r.px, as pn(r.pn) did not throw
          px = r.px;
      }
  
      template<class Y>
      shared_ptr( weak_ptr<Y> const & r, boost::detail::sp_nothrow_tag )
      BOOST_NOEXCEPT : px( 0 ), pn( r.pn, boost::detail::sp_nothrow_tag() )
      {
          if( !pn.empty() )
          {
              px = r.px;
          }
      }
  
      template<class Y>
  #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
  
      shared_ptr( shared_ptr<Y> const & r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
  
  #else
  
      shared_ptr( shared_ptr<Y> const & r )
  
  #endif
      BOOST_NOEXCEPT : px( r.px ), pn( r.pn )
      {
          boost::detail::sp_assert_convertible< Y, T >();
      }
  
      // aliasing
      template< class Y >
      shared_ptr( shared_ptr<Y> const & r, element_type * p ) BOOST_NOEXCEPT : px( p ), pn( r.pn )
      {
      }
  
  #ifndef BOOST_NO_AUTO_PTR
  
      template<class Y>
      explicit shared_ptr( std::auto_ptr<Y> & r ): px(r.get()), pn()
      {
          boost::detail::sp_assert_convertible< Y, T >();
  
          Y * tmp = r.get();
          pn = boost::detail::shared_count( r );
  
          boost::detail::sp_deleter_construct( this, tmp );
      }
  
  #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  
      template<class Y>
      shared_ptr( std::auto_ptr<Y> && r ): px(r.get()), pn()
      {
          boost::detail::sp_assert_convertible< Y, T >();
  
          Y * tmp = r.get();
          pn = boost::detail::shared_count( r );
  
          boost::detail::sp_deleter_construct( this, tmp );
      }
  
  #elif !defined( BOOST_NO_SFINAE ) && !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
      template<class Ap>
      explicit shared_ptr( Ap r, typename boost::detail::sp_enable_if_auto_ptr<Ap, int>::type = 0 ): px( r.get() ), pn()
      {
          typedef typename Ap::element_type Y;
  
          boost::detail::sp_assert_convertible< Y, T >();
  
          Y * tmp = r.get();
          pn = boost::detail::shared_count( r );
  
          boost::detail::sp_deleter_construct( this, tmp );
      }
  
  #endif // BOOST_NO_SFINAE, BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  
  #endif // BOOST_NO_AUTO_PTR
  
  #if !defined( BOOST_NO_CXX11_SMART_PTR ) && !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  
      template< class Y, class D >
      shared_ptr( std::unique_ptr< Y, D > && r ): px( r.get() ), pn()
      {
          boost::detail::sp_assert_convertible< Y, T >();
  
          typename std::unique_ptr< Y, D >::pointer tmp = r.get();
          pn = boost::detail::shared_count( r );
  
          boost::detail::sp_deleter_construct( this, tmp );
      }
  
  #endif
  
      // assignment
  
      shared_ptr & operator=( shared_ptr const & r ) BOOST_NOEXCEPT
      {
          this_type(r).swap(*this);
          return *this;
      }
  
  #if !defined(BOOST_MSVC) || (BOOST_MSVC >= 1400)
  
      template<class Y>
      shared_ptr & operator=(shared_ptr<Y> const & r) BOOST_NOEXCEPT
      {
          this_type(r).swap(*this);
          return *this;
      }
  
  #endif
  
  #ifndef BOOST_NO_AUTO_PTR
  
      template<class Y>
      shared_ptr & operator=( std::auto_ptr<Y> & r )
      {
          this_type( r ).swap( *this );
          return *this;
      }
  
  #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  
      template<class Y>
      shared_ptr & operator=( std::auto_ptr<Y> && r )
      {
          this_type( static_cast< std::auto_ptr<Y> && >( r ) ).swap( *this );
          return *this;
      }
  
  #elif !defined( BOOST_NO_SFINAE ) && !defined( BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION )
  
      template<class Ap>
      typename boost::detail::sp_enable_if_auto_ptr< Ap, shared_ptr & >::type operator=( Ap r )
      {
          this_type( r ).swap( *this );
          return *this;
      }
  
  #endif // BOOST_NO_SFINAE, BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
  
  #endif // BOOST_NO_AUTO_PTR
  
  #if !defined( BOOST_NO_CXX11_SMART_PTR ) && !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  
      template<class Y, class D>
      shared_ptr & operator=( std::unique_ptr<Y, D> && r )
      {
          this_type( static_cast< std::unique_ptr<Y, D> && >( r ) ).swap(*this);
          return *this;
      }
  
  #endif
  
  // Move support
  
  #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
  
      shared_ptr( shared_ptr && r ) BOOST_NOEXCEPT : px( r.px ), pn()
      {
          pn.swap( r.pn );
          r.px = 0;
      }
  
      template<class Y>
  #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
  
      shared_ptr( shared_ptr<Y> && r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() )
  
  #else
  
      shared_ptr( shared_ptr<Y> && r )
  
  #endif
      BOOST_NOEXCEPT : px( r.px ), pn()
      {
          boost::detail::sp_assert_convertible< Y, T >();
  
          pn.swap( r.pn );
          r.px = 0;
      }
  
      shared_ptr & operator=( shared_ptr && r ) BOOST_NOEXCEPT
      {
          this_type( static_cast< shared_ptr && >( r ) ).swap( *this );
          return *this;
      }
  
      template<class Y>
      shared_ptr & operator=( shared_ptr<Y> && r ) BOOST_NOEXCEPT
      {
          this_type( static_cast< shared_ptr<Y> && >( r ) ).swap( *this );
          return *this;
      }
  
  #endif
  
  #if !defined( BOOST_NO_CXX11_NULLPTR )
  
      shared_ptr & operator=( boost::detail::sp_nullptr_t ) BOOST_NOEXCEPT // never throws
      {
          this_type().swap(*this);
          return *this;
      }
  
  #endif
  
      void reset() BOOST_NOEXCEPT // never throws in 1.30+
      {
          this_type().swap(*this);
      }
  
      template<class Y> void reset( Y * p ) // Y must be complete
      {
          BOOST_ASSERT( p == 0 || p != px ); // catch self-reset errors
          this_type( p ).swap( *this );
      }
  
      template<class Y, class D> void reset( Y * p, D d )
      {
          this_type( p, d ).swap( *this );
      }
  
      template<class Y, class D, class A> void reset( Y * p, D d, A a )
      {
          this_type( p, d, a ).swap( *this );
      }
  
      template<class Y> void reset( shared_ptr<Y> const & r, element_type * p )
      {
          this_type( r, p ).swap( *this );
      }
      
      // never throws (but has a BOOST_ASSERT in it, so not marked with BOOST_NOEXCEPT)
      typename boost::detail::sp_dereference< T >::type operator* () const
      {
          BOOST_ASSERT( px != 0 );
          return *px;
      }
      
      // never throws (but has a BOOST_ASSERT in it, so not marked with BOOST_NOEXCEPT)
      typename boost::detail::sp_member_access< T >::type operator-> () const 
      {
          BOOST_ASSERT( px != 0 );
          return px;
      }
      
      // never throws (but has a BOOST_ASSERT in it, so not marked with BOOST_NOEXCEPT)
      typename boost::detail::sp_array_access< T >::type operator[] ( std::ptrdiff_t i ) const
      {
          BOOST_ASSERT( px != 0 );
          BOOST_ASSERT( i >= 0 && ( i < boost::detail::sp_extent< T >::value || boost::detail::sp_extent< T >::value == 0 ) );
  
          return px[ i ];
      }
  
      element_type * get() const BOOST_NOEXCEPT
      {
          return px;
      }
  
  // implicit conversion to "bool"
  #include <boost/smart_ptr/detail/operator_bool.hpp>
  
      bool unique() const BOOST_NOEXCEPT
      {
          return pn.unique();
      }
  
      long use_count() const BOOST_NOEXCEPT
      {
          return pn.use_count();
      }
  
      void swap( shared_ptr & other ) BOOST_NOEXCEPT
      {
          std::swap(px, other.px);
          pn.swap(other.pn);
      }
  
      template<class Y> bool owner_before( shared_ptr<Y> const & rhs ) const BOOST_NOEXCEPT
      {
          return pn < rhs.pn;
      }
  
      template<class Y> bool owner_before( weak_ptr<Y> const & rhs ) const BOOST_NOEXCEPT
      {
          return pn < rhs.pn;
      }
  
      void * _internal_get_deleter( boost::detail::sp_typeinfo const & ti ) const BOOST_NOEXCEPT
      {
          return pn.get_deleter( ti );
      }
  
      void * _internal_get_untyped_deleter() const BOOST_NOEXCEPT
      {
          return pn.get_untyped_deleter();
      }
  
      bool _internal_equiv( shared_ptr const & r ) const BOOST_NOEXCEPT
      {
          return px == r.px && pn == r.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 shared_ptr;
      template<class Y> friend class weak_ptr;
  
  
  #endif
  
      element_type * px;                 // contained pointer
      boost::detail::shared_count pn;    // reference counter
  
  };  // shared_ptr
  
  template<class T, class U> inline bool operator==(shared_ptr<T> const & a, shared_ptr<U> const & b) BOOST_NOEXCEPT
  {
      return a.get() == b.get();
  }
  
  template<class T, class U> inline bool operator!=(shared_ptr<T> const & a, shared_ptr<U> const & b) BOOST_NOEXCEPT
  {
      return a.get() != b.get();
  }
  
  #if __GNUC__ == 2 && __GNUC_MINOR__ <= 96
  
  // Resolve the ambiguity between our op!= and the one in rel_ops
  
  template<class T> inline bool operator!=(shared_ptr<T> const & a, shared_ptr<T> const & b) BOOST_NOEXCEPT
  {
      return a.get() != b.get();
  }
  
  #endif
  
  #if !defined( BOOST_NO_CXX11_NULLPTR )
  
  template<class T> inline bool operator==( shared_ptr<T> const & p, boost::detail::sp_nullptr_t ) BOOST_NOEXCEPT
  {
      return p.get() == 0;
  }
  
  template<class T> inline bool operator==( boost::detail::sp_nullptr_t, shared_ptr<T> const & p ) BOOST_NOEXCEPT
  {
      return p.get() == 0;
  }
  
  template<class T> inline bool operator!=( shared_ptr<T> const & p, boost::detail::sp_nullptr_t ) BOOST_NOEXCEPT
  {
      return p.get() != 0;
  }
  
  template<class T> inline bool operator!=( boost::detail::sp_nullptr_t, shared_ptr<T> const & p ) BOOST_NOEXCEPT
  {
      return p.get() != 0;
  }
  
  #endif
  
  template<class T, class U> inline bool operator<(shared_ptr<T> const & a, shared_ptr<U> const & b) BOOST_NOEXCEPT
  {
      return a.owner_before( b );
  }
  
  template<class T> inline void swap(shared_ptr<T> & a, shared_ptr<T> & b) BOOST_NOEXCEPT
  {
      a.swap(b);
  }
  
  template<class T, class U> shared_ptr<T> static_pointer_cast( shared_ptr<U> const & r ) BOOST_NOEXCEPT
  {
      (void) static_cast< T* >( static_cast< U* >( 0 ) );
  
      typedef typename shared_ptr<T>::element_type E;
  
      E * p = static_cast< E* >( r.get() );
      return shared_ptr<T>( r, p );
  }
  
  template<class T, class U> shared_ptr<T> const_pointer_cast( shared_ptr<U> const & r ) BOOST_NOEXCEPT
  {
      (void) const_cast< T* >( static_cast< U* >( 0 ) );
  
      typedef typename shared_ptr<T>::element_type E;
  
      E * p = const_cast< E* >( r.get() );
      return shared_ptr<T>( r, p );
  }
  
  template<class T, class U> shared_ptr<T> dynamic_pointer_cast( shared_ptr<U> const & r ) BOOST_NOEXCEPT
  {
      (void) dynamic_cast< T* >( static_cast< U* >( 0 ) );
  
      typedef typename shared_ptr<T>::element_type E;
  
      E * p = dynamic_cast< E* >( r.get() );
      return p? shared_ptr<T>( r, p ): shared_ptr<T>();
  }
  
  template<class T, class U> shared_ptr<T> reinterpret_pointer_cast( shared_ptr<U> const & r ) BOOST_NOEXCEPT
  {
      (void) reinterpret_cast< T* >( static_cast< U* >( 0 ) );
  
      typedef typename shared_ptr<T>::element_type E;
  
      E * p = reinterpret_cast< E* >( r.get() );
      return shared_ptr<T>( r, p );
  }
  
  // get_pointer() enables boost::mem_fn to recognize shared_ptr
  
  template<class T> inline typename shared_ptr<T>::element_type * get_pointer(shared_ptr<T> const & p) BOOST_NOEXCEPT
  {
      return p.get();
  }
  
  // operator<<
  
  #if !defined(BOOST_NO_IOSTREAM)
  
  #if defined(BOOST_NO_TEMPLATED_IOSTREAMS) || ( defined(__GNUC__) &&  (__GNUC__ < 3) )
  
  template<class Y> std::ostream & operator<< (std::ostream & os, shared_ptr<Y> const & p)
  {
      os << p.get();
      return os;
  }
  
  #else
  
  // in STLport's no-iostreams mode no iostream symbols can be used
  #ifndef _STLP_NO_IOSTREAMS
  
  # if defined(BOOST_MSVC) && BOOST_WORKAROUND(BOOST_MSVC, < 1300 && __SGI_STL_PORT)
  // MSVC6 has problems finding std::basic_ostream through the using declaration in namespace _STL
  using std::basic_ostream;
  template<class E, class T, class Y> basic_ostream<E, T> & operator<< (basic_ostream<E, T> & os, shared_ptr<Y> const & p)
  # else
  template<class E, class T, class Y> std::basic_ostream<E, T> & operator<< (std::basic_ostream<E, T> & os, shared_ptr<Y> const & p)
  # endif
  {
      os << p.get();
      return os;
  }
  
  #endif // _STLP_NO_IOSTREAMS
  
  #endif // __GNUC__ < 3
  
  #endif // !defined(BOOST_NO_IOSTREAM)
  
  // get_deleter
  
  namespace detail
  {
  
  #if ( defined(__GNUC__) && BOOST_WORKAROUND(__GNUC__, < 3) ) || \
      ( defined(__EDG_VERSION__) && BOOST_WORKAROUND(__EDG_VERSION__, <= 238) ) || \
      ( defined(__HP_aCC) && BOOST_WORKAROUND(__HP_aCC, <= 33500) )
  
  // g++ 2.9x doesn't allow static_cast<X const *>(void *)
  // apparently EDG 2.38 and HP aCC A.03.35 also don't accept it
  
  template<class D, class T> D * basic_get_deleter(shared_ptr<T> const & p)
  {
      void const * q = p._internal_get_deleter(BOOST_SP_TYPEID(D));
      return const_cast<D *>(static_cast<D const *>(q));
  }
  
  #else
  
  template<class D, class T> D * basic_get_deleter( shared_ptr<T> const & p ) BOOST_NOEXCEPT
  {
      return static_cast<D *>( p._internal_get_deleter(BOOST_SP_TYPEID(D)) );
  }
  
  #endif
  
  class esft2_deleter_wrapper
  {
  private:
  
      shared_ptr<void const volatile> deleter_;
  
  public:
  
      esft2_deleter_wrapper()
      {
      }
  
      template< class T > void set_deleter( shared_ptr<T> const & deleter )
      {
          deleter_ = deleter;
      }
  
      template<typename D> D* get_deleter() const BOOST_NOEXCEPT
      {
          return boost::detail::basic_get_deleter<D>( deleter_ );
      }
  
      template< class T> void operator()( T* )
      {
          BOOST_ASSERT( deleter_.use_count() <= 1 );
          deleter_.reset();
      }
  };
  
  } // namespace detail
  
  template<class D, class T> D * get_deleter( shared_ptr<T> const & p ) BOOST_NOEXCEPT
  {
      D *del = boost::detail::basic_get_deleter<D>(p);
  
      if(del == 0)
      {
          boost::detail::esft2_deleter_wrapper *del_wrapper = boost::detail::basic_get_deleter<boost::detail::esft2_deleter_wrapper>(p);
  // The following get_deleter method call is fully qualified because
  // older versions of gcc (2.95, 3.2.3) fail to compile it when written del_wrapper->get_deleter<D>()
          if(del_wrapper) del = del_wrapper->::boost::detail::esft2_deleter_wrapper::get_deleter<D>();
      }
  
      return del;
  }
  
  // atomic access
  
  #if !defined(BOOST_SP_NO_ATOMIC_ACCESS)
  
  template<class T> inline bool atomic_is_lock_free( shared_ptr<T> const * /*p*/ ) BOOST_NOEXCEPT
  {
      return false;
  }
  
  template<class T> shared_ptr<T> atomic_load( shared_ptr<T> const * p )
  {
      boost::detail::spinlock_pool<2>::scoped_lock lock( p );
      return *p;
  }
  
  template<class T> inline shared_ptr<T> atomic_load_explicit( shared_ptr<T> const * p, /*memory_order mo*/ int )
  {
      return atomic_load( p );
  }
  
  template<class T> void atomic_store( shared_ptr<T> * p, shared_ptr<T> r )
  {
      boost::detail::spinlock_pool<2>::scoped_lock lock( p );
      p->swap( r );
  }
  
  template<class T> inline void atomic_store_explicit( shared_ptr<T> * p, shared_ptr<T> r, /*memory_order mo*/ int )
  {
      atomic_store( p, r ); // std::move( r )
  }
  
  template<class T> shared_ptr<T> atomic_exchange( shared_ptr<T> * p, shared_ptr<T> r )
  {
      boost::detail::spinlock & sp = boost::detail::spinlock_pool<2>::spinlock_for( p );
  
      sp.lock();
      p->swap( r );
      sp.unlock();
  
      return r; // return std::move( r )
  }
  
  template<class T> shared_ptr<T> atomic_exchange_explicit( shared_ptr<T> * p, shared_ptr<T> r, /*memory_order mo*/ int )
  {
      return atomic_exchange( p, r ); // std::move( r )
  }
  
  template<class T> bool atomic_compare_exchange( shared_ptr<T> * p, shared_ptr<T> * v, shared_ptr<T> w )
  {
      boost::detail::spinlock & sp = boost::detail::spinlock_pool<2>::spinlock_for( p );
  
      sp.lock();
  
      if( p->_internal_equiv( *v ) )
      {
          p->swap( w );
  
          sp.unlock();
  
          return true;
      }
      else
      {
          shared_ptr<T> tmp( *p );
  
          sp.unlock();
  
          tmp.swap( *v );
          return false;
      }
  }
  
  template<class T> inline bool atomic_compare_exchange_explicit( shared_ptr<T> * p, shared_ptr<T> * v, shared_ptr<T> w, /*memory_order success*/ int, /*memory_order failure*/ int )
  {
      return atomic_compare_exchange( p, v, w ); // std::move( w )
  }
  
  #endif // !defined(BOOST_SP_NO_ATOMIC_ACCESS)
  
  // hash_value
  
  template< class T > struct hash;
  
  template< class T > std::size_t hash_value( boost::shared_ptr<T> const & p ) BOOST_NOEXCEPT
  {
      return boost::hash< T* >()( p.get() );
  }
  
  } // namespace boost
  
  #endif  // #ifndef BOOST_SMART_PTR_SHARED_PTR_HPP_INCLUDED
  