vtkWeakPointerBase.h

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

  Program:   Visualization Toolkit
  Module:    vtkWeakPointerBase.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 vtkWeakPointerBase_h
#define vtkWeakPointerBase_h

#include "vtkCommonCoreModule.h" // For export macro
#include "vtkObjectBase.h"

class vtkObjectBaseToWeakPointerBaseFriendship;

class VTKCOMMONCORE_EXPORT vtkWeakPointerBase
{
public:
  vtkWeakPointerBase() : Object(nullptr) {}

  vtkWeakPointerBase(vtkObjectBase* r);

  vtkWeakPointerBase(const vtkWeakPointerBase& r);

  ~vtkWeakPointerBase();


  vtkWeakPointerBase& operator=(vtkObjectBase* r);
  vtkWeakPointerBase& operator=(const vtkWeakPointerBase& r);

  vtkObjectBase* GetPointer() const
  {
    // Inline implementation so smart pointer comparisons can be fully
    // inlined.
    return this->Object;
  }

private:
  friend class vtkObjectBaseToWeakPointerBaseFriendship;

protected:

  // Initialize weak pointer to given object.
  class NoReference {};
  vtkWeakPointerBase(vtkObjectBase* r, const NoReference&);

  // Pointer to the actual object.
  vtkObjectBase* Object;
};

//----------------------------------------------------------------------------
#define VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(op) \
  inline bool \
  operator op (const vtkWeakPointerBase& l, const vtkWeakPointerBase& r) \
  { \
    return (static_cast<void*>(l.GetPointer()) op \
            static_cast<void*>(r.GetPointer())); \
  } \
  inline bool \
  operator op (vtkObjectBase* l, const vtkWeakPointerBase& r) \
  { \
    return (static_cast<void*>(l) op static_cast<void*>(r.GetPointer())); \
  } \
  inline bool \
  operator op (const vtkWeakPointerBase& l, vtkObjectBase* r) \
  { \
    return (static_cast<void*>(l.GetPointer()) op static_cast<void*>(r)); \
  }

VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(==)
VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(!=)
VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(<)
VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(<=)
VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(>)
VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(>=)

#undef VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR

VTKCOMMONCORE_EXPORT ostream& operator << (ostream& os,
                                        const vtkWeakPointerBase& p);

#endif
// VTK-HeaderTest-Exclude: vtkWeakPointerBase.h