OW_Reference.hpp

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#ifndef OW_REFERENCE_HPP_
#define OW_REFERENCE_HPP_
#include "OW_config.h"
#include "OW_ReferenceBase.hpp"

namespace OW_NAMESPACE
{

template<class T>
class Reference : 
#if !defined(__GNUC__) || __GNUC__ > 2 // because of a gcc 2.95 ICE
   private ReferenceBase
#else
   public ReferenceBase
#endif
{
   public:
      typedef T element_type;

      Reference();
      explicit Reference(T* ptr);
      Reference(const Reference<T>& arg);
      
      /* construct out of a reference to a derived type.  U should be
      derived from T */
      template <class U>
      Reference(const Reference<U>& arg);
      ~Reference();
      Reference<T>& operator= (const Reference<T>& arg);
      Reference<T>& operator= (T* newObj);
      void swap(Reference<T>& arg);
      T* operator->() const;
      T& operator*() const;
      T* getPtr() const;
      bool isNull() const OW_DEPRECATED; // in 3.1.0
      typedef T* volatile Reference::*safe_bool;
      operator safe_bool () const
         {  return (m_pObj ? &Reference::m_pObj : 0); }
      bool operator!() const
         {  return !m_pObj; }
      template <class U>
      Reference<U> cast_to() const;
      template <class U>
      void useRefCountOf(const Reference<U>&);
#if !defined(__GNUC__) || __GNUC__ > 2 // causes gcc 2.95 to ICE
      /* This is so the templated constructor will work */
      template <class U> friend class Reference;
   private:
#endif
      void decRef();
      T* volatile m_pObj;
};
template<class T>
inline Reference<T>::Reference()
   : ReferenceBase(), m_pObj(0)
{
}
template<class T>
inline Reference<T>::Reference(T* ptr)
   : ReferenceBase(), m_pObj(ptr)
{
}
template<class T>
inline Reference<T>::Reference(const Reference<T>& arg)
   : ReferenceBase(arg), m_pObj(arg.m_pObj)
{
}
template<class T>
template<class U>
inline Reference<T>::Reference(const Reference<U>& arg)
  : ReferenceBase(arg),
  m_pObj(arg.m_pObj)
{
}
template<class T>
inline Reference<T>::~Reference()
{
   // we don't catch(...) here because nothing we do will throw, and any 
   // class we wrap should have a non-throwing destructor.
   decRef();
}
template<class T>
inline void Reference<T>::decRef()
{
   typedef char type_must_be_complete[sizeof(T)];
   if (ReferenceBase::decRef())
   {
      delete m_pObj;
   }
}
template<class T>
inline Reference<T>& Reference<T>::operator= (const Reference<T>& arg)
{
   Reference<T>(arg).swap(*this);
   return *this;
}
template<class T>
inline Reference<T>& Reference<T>::operator= (T* newObj)
{
   Reference<T>(newObj).swap(*this);
   return *this;
}
template <class T>
inline void Reference<T>::swap(Reference<T>& arg)
{
   ReferenceBase::swap(arg);
   RefSwap(m_pObj, arg.m_pObj);
}
template<class T>
inline T* Reference<T>::operator->() const
{
#ifdef OW_CHECK_NULL_REFERENCES
   checkNull(this);
   checkNull(m_pObj);
#endif
   
   return m_pObj;
}
template<class T>
inline T& Reference<T>::operator*() const
{
#ifdef OW_CHECK_NULL_REFERENCES
   checkNull(this);
   checkNull(m_pObj);
#endif
   
   return *(m_pObj);
}
template<class T>
inline T* Reference<T>::getPtr() const
{
   return m_pObj;
}
template<class T>
inline bool Reference<T>::isNull() const
{
   return (m_pObj == 0);
}
template <class T>
template <class U>
inline Reference<U>
Reference<T>::cast_to() const
{
   Reference<U> rval;
   rval.m_pObj = dynamic_cast<U*>(m_pObj);
   if (rval.m_pObj)
   {
      rval.useRefCountOf(*this);
   }
   return rval;
}
template <class T>
template <class U>
inline void
Reference<T>::useRefCountOf(const Reference<U>& arg)
{
   ReferenceBase::useRefCountOf(arg);
}
// Comparisons
template <class T, class U>
inline bool operator==(const Reference<T>& a, const Reference<U>& b)
{
   return a.getPtr() == b.getPtr();
}
template <class T, class U>
inline bool operator!=(const Reference<T>& a, const Reference<U>& b)
{
   return a.getPtr() != b.getPtr();
}
#if __GNUC__ == 2 && __GNUC_MINOR__ <= 96
// Resolve the ambiguity between our op!= and the one in rel_ops
template <class T>
inline bool operator!=(const Reference<T>& a, const Reference<T>& b)
{
   return a.getPtr() != b.getPtr();
}
#endif

template <class T, class U>
inline bool operator<(const Reference<T>& a, const Reference<U>& b)
{
   return a.getPtr() < b.getPtr();
}

} // end namespace OW_NAMESPACE

#endif   // OW_REFERENCE_HPP_

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