berryWeakPointer.h

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/*============================================================================
 
The Medical Imaging Interaction Toolkit (MITK)
 
Copyright (c) German Cancer Research Center (DKFZ)
All rights reserved.
 
Use of this source code is governed by a 3-clause BSD license that can be
found in the LICENSE file.
 
============================================================================*/
 
#ifndef __BERRY_WEAK_POINTER_H__
#define __BERRY_WEAK_POINTER_H__
 
#include <exception>
#include <iostream>
 
#include "berryMessage.h"
#include "berrySmartPointer.h"
 
namespace berry
{
 
template<class TObjectType>
class WeakPointer
{
 
public:
 
  typedef TObjectType ObjectType;
 
  WeakPointer() :
    m_Pointer(nullptr)
  {
 
  }
 
  template<class Other>
  explicit WeakPointer(berry::SmartPointer<Other> sptr) :
    m_Pointer(dynamic_cast<ObjectType*>(sptr.GetPointer()))
  {
 
    if (m_Pointer)
      m_Pointer->AddDestroyListener(MessageDelegate<WeakPointer> (this,
        &WeakPointer::ObjectDestroyed));
 
  }
 
  template<class Other>
  WeakPointer(const WeakPointer<Other>& p) :
    m_Pointer(dynamic_cast<ObjectType*>(p.m_Pointer))
  {
    if (m_Pointer)
      m_Pointer->AddDestroyListener(MessageDelegate<WeakPointer> (this,
        &WeakPointer::ObjectDestroyed));
  }
 
  WeakPointer(const WeakPointer& p) :
    m_Pointer(p.m_Pointer)
  {
    if (m_Pointer)
      m_Pointer->AddDestroyListener(MessageDelegate<WeakPointer> (this,
        &WeakPointer::ObjectDestroyed));
  }
 
  template<class Other>
  WeakPointer &operator =(const SmartPointer<Other> &r)
  {
    if (m_Pointer)
      m_Pointer->RemoveDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
 
    m_Pointer = const_cast<ObjectType*>(r.GetPointer());
    if (m_Pointer)
      m_Pointer->AddDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
 
    return *this;
  }
 
  WeakPointer& operator=(const WeakPointer& other)
  {
    if (m_Pointer)
      m_Pointer->RemoveDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
 
    this->m_Pointer = other.m_Pointer;
    if (m_Pointer)
      m_Pointer->AddDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
 
    return *this;
  }
 
  template<class Other>
  WeakPointer& operator=(const WeakPointer<Other>& other)
  {
    if (m_Pointer)
      m_Pointer->RemoveDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
 
    this->m_Pointer = const_cast<ObjectType*>(other.m_Pointer);
    if (m_Pointer)
      m_Pointer->AddDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
 
    return *this;
  }
 
  template<typename R>
  bool operator ==(const R* o) const
  {
    return (m_Pointer == nullptr ? o == nullptr : (o && m_Pointer->operator==(o)));
  }
 
  template<typename R>
  bool operator ==(const WeakPointer<R>& r) const
  {
    const R* o = r.m_Pointer;
    return (m_Pointer == nullptr ? o == nullptr : (o && m_Pointer->operator==(o)));
  }
 
  bool operator <(const WeakPointer &r) const
  {
    return (void*) m_Pointer < (void*) r.m_Pointer;
  }
 
  SmartPointer<ObjectType> Lock() const
  {
    SmartPointer<ObjectType> sp(m_Pointer);
    return sp;
  }
 
  void Reset()
  {
    if (m_Pointer)
      m_Pointer->RemoveDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
 
    m_Pointer = nullptr;
  }
 
  bool Expired() const
  {
    return m_Pointer == nullptr;
  }
 
  ~ WeakPointer()
  {
    if (m_Pointer)
      m_Pointer->RemoveDestroyListener(MessageDelegate<WeakPointer> (this,
          &WeakPointer::ObjectDestroyed));
  }
 
private:
 
  template<class Y> friend class SmartPointer;
  template<class Y> friend class WeakPointer;
 
  ObjectType *m_Pointer;
 
  void ObjectDestroyed()
  {
    m_Pointer = nullptr;
  }
 
};
 
}
 
#endif // __BERRY_WEAK_POINTER_H__