dox/Common/Core/vtkWeakPointer.h

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/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkWeakPointer.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/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 notice for more information.

=========================================================================*/
#ifndef __vtkWeakPointer_h
#define __vtkWeakPointer_h

#include "vtkWeakPointerBase.h"

template <class T>
class vtkWeakPointer: public vtkWeakPointerBase
{
public:
  vtkWeakPointer() {}

  vtkWeakPointer(T* r): vtkWeakPointerBase(r) {}

  vtkWeakPointer(const vtkWeakPointerBase& r): vtkWeakPointerBase(r) {}


  vtkWeakPointer& operator=(T* r)
    {
    this->vtkWeakPointerBase::operator=(r);
    return *this;
    }


  vtkWeakPointer& operator=(const vtkWeakPointerBase& r)
    {
    this->vtkWeakPointerBase::operator=(r);
    return *this;
    }


  T* GetPointer() const
    {
    return static_cast<T*>(this->Object);
    }


  operator T* () const
    {
    return static_cast<T*>(this->Object);
    }


  T& operator*() const
    {
    return *static_cast<T*>(this->Object);
    }


  T* operator->() const
    {
    return static_cast<T*>(this->Object);
    }

  // Work-around for HP and IBM overload resolution bug.  Since
  // NullPointerOnly is a private type the only pointer value that can
  // be passed by user code is a null pointer.  This operator will be
  // chosen by the compiler when comparing against null explicitly and
  // avoid the bogus ambiguous overload error.
#if defined(__HP_aCC) || defined(__IBMCPP__)
# define VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND(op) \
  bool operator op (NullPointerOnly*) const              \
    {                                                     \
    return ::operator op (*this, 0);                      \
    }
private:
  class NullPointerOnly {};
public:
  VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND(==)
  VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND(!=)
  VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND(<)
  VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND(<=)
  VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND(>)
  VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND(>=)
# undef VTK_WEAK_POINTER_DEFINE_OPERATOR_WORKAROUND
#endif
protected:
  vtkWeakPointer(T* r, const NoReference& n): vtkWeakPointerBase(r, n) {}
private:
  // These are purposely not implemented to prevent callers from
  // trying to take references from other smart pointers.
  void TakeReference(const vtkWeakPointerBase&);  // Not implemented.
  static void Take(const vtkWeakPointerBase&);  // Not implemented.
};

#define VTK_WEAK_POINTER_DEFINE_OPERATOR(op) \
  template <class T> \
  inline bool \
  operator op (const vtkWeakPointer<T>& l, const vtkWeakPointer<T>& r) \
    { \
    return (l.GetPointer() op r.GetPointer()); \
    } \
  template <class T> \
  inline bool operator op (T* l, const vtkWeakPointer<T>& r) \
    { \
    return (l op r.GetPointer()); \
    } \
  template <class T> \
  inline bool operator op (const vtkWeakPointer<T>& l, T* r) \
    { \
    return (l.GetPointer() op r); \
    }


VTK_WEAK_POINTER_DEFINE_OPERATOR(==)
VTK_WEAK_POINTER_DEFINE_OPERATOR(!=)
VTK_WEAK_POINTER_DEFINE_OPERATOR(<)
VTK_WEAK_POINTER_DEFINE_OPERATOR(<=)
VTK_WEAK_POINTER_DEFINE_OPERATOR(>)
VTK_WEAK_POINTER_DEFINE_OPERATOR(>=)

#undef VTK_WEAK_POINTER_DEFINE_OPERATOR


template <class T>
inline ostream& operator << (ostream& os, const vtkWeakPointer<T>& p)
{
  return os << static_cast<const vtkWeakPointerBase&>(p);
}


#endif


// VTK-HeaderTest-Exclude: vtkWeakPointer.h