Reference.hpp

Go to the documentation of this file.

/*******************************************************************************
* Copyright (C) 2005, Vintela, Inc. All rights reserved.
* Copyright (C) 2006, Novell, Inc. All rights reserved.
* 
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 
*     * Redistributions of source code must retain the above copyright notice,
*       this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright
*       notice, this list of conditions and the following disclaimer in the
*       documentation and/or other materials provided with the distribution.
*     * Neither the name of 
*       Vintela, Inc., 
*       nor Novell, Inc., 
*       nor the names of its contributors or employees may be used to 
*       endorse or promote products derived from this software without 
*       specific prior written permission.
* 
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*******************************************************************************/


#ifndef BLOCXX_REFERENCE_HPP_
#define BLOCXX_REFERENCE_HPP_
#include "blocxx/BLOCXX_config.h"
#include "blocxx/ReferenceBase.hpp"
#include "blocxx/ReferenceHelpers.hpp"
#include "blocxx/SafeBool.hpp"

namespace BLOCXX_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 BLOCXX_DEPRECATED; // in 3.1.0

      BLOCXX_SAFE_BOOL_IMPL(Reference, T* volatile, Reference::m_pObj, 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 BLOCXX_CHECK_NULL_REFERENCES
   ReferenceHelpers::checkNull(this);
   ReferenceHelpers::checkNull(m_pObj);
#endif
   
   return m_pObj;
}
template<class T>
inline T& Reference<T>::operator*() const
{
#ifdef BLOCXX_CHECK_NULL_REFERENCES
   ReferenceHelpers::checkNull(this);
   ReferenceHelpers::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 BLOCXX_NAMESPACE

#endif   // BLOCXX_REFERENCE_HPP_