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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: itkSmartPointerForwardReference.h
Language: C++
Date: $Date$
Version: $Revision$
Copyright (c) Insight Software Consortium. All rights reserved.
See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#ifndef __itkSmartPointerForwardReference_h
#define __itkSmartPointerForwardReference_h
#include "itkMacro.h"
#include "itkWeakPointer.h"
#include <iostream>
namespace itk
{
/** \class SmartPointerForwardReference
* \brief Implements transparent reference counting in situations where forward
* references / cyclic include dependencies are a problem.
*
* SmartPointerForwardReference implements reference counting by overloading
* operator -> (and *) among others. This allows natural interface
* to the class referred to by the pointer without having to invoke
* special Register()/UnRegister() methods directly.
*
* This class is nearly identical to itkSmartPointer except that is used in
* situations where forward references or cyclic include dependencies become
* a problem. This class requires that the .h file is included in the .h file
* of the class using it, and the .txx file is included in the .cxx/.txx file
* of the class using it. (Make sure that SmartPointerForwardReference.txx is
* included last in the .cxx/.txx list of includes.)
*
* \ingroup ITKSystemObjects
* \ingroup DataAccess
*/
template <class T>
class ITK_EXPORT SmartPointerForwardReference
{
public:
/** Constructor */
SmartPointerForwardReference ()
{m_Pointer = 0;}
/** Const constructor */
SmartPointerForwardReference (const SmartPointerForwardReference<T> &p);
/** Construct from a WeakPointer */
SmartPointerForwardReference (const WeakPointer<T> &p);
/** Constructor to pointer p */
SmartPointerForwardReference (T *p);
/** Destructor */
~SmartPointerForwardReference ();
/** Overload operator -> */
T *operator -> () const;
/** Return pointer to object. */
operator T * () const;
/** Access function to pointer. */
T *GetPointer () const;
/** Comparison of pointers. Less than comparison. */
bool operator < (const SmartPointerForwardReference &r);
/** Comparison of pointers. Greater than comparison. */
bool operator > (const SmartPointerForwardReference &r);
/** Comparison of pointers. Less than or equal to comparison. */
bool operator <= (const SmartPointerForwardReference &r);
/** Comparison of pointers. Greater than or equal to comparison. */
bool operator >= (const SmartPointerForwardReference &r);
/** Overload operator assignment. */
SmartPointerForwardReference &operator = (const SmartPointerForwardReference &r);
/** Overload operator assignment. */
SmartPointerForwardReference &operator = (const WeakPointer<T> &r);
/** Overload operator assignment. */
SmartPointerForwardReference &operator = (T *r);
/** Function to print object pointed to */
T *Print (std::ostream& os) const;
private:
/** The pointer to the object referrred to by this smart pointer. */
T* m_Pointer;
void Register();
void UnRegister();
};
template <typename T>
std::ostream& operator<< (std::ostream& os, SmartPointerForwardReference<T> p)
{
p.Print(os);
return os;
}
} // end namespace itk
#endif
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