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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.
=========================================================================*/
// .NAME vtkWeakPointerBase - Non-templated superclass for vtkWeakPointer.
// .SECTION Description
// vtkWeakPointerBase holds a pointer to a vtkObjectBase or subclass
// instance, but it never affects the reference count of the vtkObjectBase. However,
// when the vtkObjectBase referred to is destroyed, the pointer gets initialized to
// NULL, thus avoid dangling references.
#ifndef __vtkWeakPointerBase_h
#define __vtkWeakPointerBase_h
#include "vtkObjectBase.h"
class vtkObjectBaseToWeakPointerBaseFriendship;
class VTK_COMMON_EXPORT vtkWeakPointerBase
{
public:
// Description:
// Initialize smart pointer to NULL.
vtkWeakPointerBase() : Object(0) {};
// Description:
// Initialize smart pointer to given object.
vtkWeakPointerBase(vtkObjectBase* r);
// Description:
// Initialize weak pointer .
vtkWeakPointerBase(const vtkWeakPointerBase& r);
// Description:
// Destroy smart pointer.
~vtkWeakPointerBase();
// Description:
// Assign object to reference. This removes any reference to an old
// object.
vtkWeakPointerBase& operator=(vtkObjectBase* r);
vtkWeakPointerBase& operator=(const vtkWeakPointerBase& r);
// Description:
// Get the contained pointer.
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;
};
//----------------------------------------------------------------------------
// Need to use vtkstd_bool type because std: :less requires bool return
// type from operators. This example should not be used to justify
// using bool elsewhere in VTK.
#define VTK_WEAK_POINTER_BASE_DEFINE_OPERATOR(op) \
inline vtkstd_bool \
operator op (const vtkWeakPointerBase& l, const vtkWeakPointerBase& r) \
{ \
return (static_cast<void*>(l.GetPointer()) op \
static_cast<void*>(r.GetPointer())); \
} \
inline vtkstd_bool \
operator op (vtkObjectBase* l, const vtkWeakPointerBase& r) \
{ \
return (static_cast<void*>(l) op static_cast<void*>(r.GetPointer())); \
} \
inline vtkstd_bool \
operator op (const vtkWeakPointerBase& l, vtkObjectBase* r) \
{ \
return (static_cast<void*>(l.GetPointer()) op static_cast<void*>(r)); \
}
// Description:
// Compare smart pointer values.
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
// Description:
// Streaming operator to print smart pointer like regular pointers.
VTK_COMMON_EXPORT ostream& operator << (ostream& os,
const vtkWeakPointerBase& p);
#endif
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