myvtm/Common/SmartPointer.h

#pragma once
#include <assert.h>
#include <winpr/interlocked.h>

template<class T> class CSmartPointer
{
public:
	CSmartPointer():m_pPoint(NULL),m_pnReference(NULL){}

	CSmartPointer(T *pPoint) :m_pPoint(pPoint), m_pnReference(NULL){}		

	CSmartPointer(const CSmartPointer<T> &Point)
		:m_pPoint(Point.m_pPoint),m_pnReference(Point.m_pnReference)
	{
		if(m_pnReference)
			InterlockedIncrement(m_pnReference);
	}

	~CSmartPointer()
	{
		Clear();
	}

	CSmartPointer<T> &operator=(T *pPoint)
	{
		if(pPoint!=m_pPoint)
		{
			Clear();
			m_pPoint=pPoint;
		}
		return *this;
	}

	CSmartPointer<T> &operator =(const CSmartPointer<T> &Point)		
	{
		if(Point.m_pPoint!=m_pPoint)
		{
			Clear();
			m_pPoint=Point.m_pPoint;
			m_pnReference=Point.m_pnReference;
			if(m_pnReference)					
				InterlockedIncrement(m_pnReference);
		}
		return *this;
	}

	bool operator ==(T *pPoint)const
	{
		return m_pPoint==pPoint;
	}

	bool operator ==(const CSmartPointer<T> &Point)const
	{
		return m_pPoint==Point.m_pPoint;
	}

	bool operator !=(T *pPoint)const
	{
		return m_pPoint!=pPoint;
	}

	bool operator !=(const CSmartPointer<T> &Point)const
	{
		return m_pPoint!=Point.m_pPoint;
	}
		
	void Attach(T *pPoint)
	{
		Attach(pPoint, NULL);
	}

	void Attach(T *pPoint,LONG *pnReference)
	{
		if(m_pPoint!=pPoint)
		{
			Clear();
			m_pPoint=pPoint;
			m_pnReference=pnReference;
			if(pnReference!=NULL && *pnReference>0)
				InterlockedIncrement(m_pnReference);
			else
				m_pnReference = new LONG(1);
		}
	}

	T *Detach()
	{
		if(m_pnReference)
		{
			if (*m_pnReference != 1)
			{
				assert(false);
				return NULL;
			}
			else
			{
				delete m_pnReference;
				m_pnReference=NULL;
			}
		}

		T *pRet=m_pPoint;
		m_pPoint=NULL;		
		return pRet;
	}

	void AddRef()
	{
		if (m_pnReference != NULL && *m_pnReference > 0)
			InterlockedIncrement(m_pnReference);
	}
	void SubRef()
	{
		if (m_pnReference)
		{
			LONG nRef = InterlockedDecrement(m_pnReference);
			if (nRef == 0)
			{
				delete m_pPoint;
				delete m_pnReference;
			}
			m_pnReference = NULL;
		}
	}

	void Clear()
	{
		if(m_pnReference) 
		{
			LONG nRef=InterlockedDecrement(m_pnReference);
			if(nRef==0)
			{
				delete m_pPoint;
				delete m_pnReference;
			}
			m_pnReference=NULL;
		}

		m_pPoint=NULL;
	}

	T *operator ->() const
	{
		return m_pPoint;
	}

	/*operator T*() const
	{
		return m_pPoint;
	}*/

	T* GetRawPointer() const
	{
		return m_pPoint;
	}

#if 1 
	template<class P>
	CSmartPointer<P> ConvertCase()
	{
		CSmartPointer<P> pRet;
		try
		{
			if (m_pnReference != NULL)
				pRet.Attach(dynamic_cast<P *>(m_pPoint),m_pnReference);
			else
				pRet = dynamic_cast<P *>(m_pPoint);			// if not managed originally, ret pointer should not be managed too!!!
		}
		catch(...)
		{
			return NULL;
		}

		return pRet;
	}
#else
	template<class P>
	CSmartPointer<P> ConvertCase() // do this a little bit brute-force
	{
		CSmartPointer<P> pRet;
		P **pp = (P**)((char*)(&pRet) + (size_t)(&((CSmartPointer*)0)->m_pPoint));
		*pp = dynamic_cast<P *>(m_pPoint);
		LONG **pr = (LONG**)((char*)(&pRet) + (size_t)(&((CSmartPointer*)0)->m_pnReference));
		*pr = m_pnReference;
		if(m_pnReference)
			InterlockedIncrement(m_pnReference);
		return pRet;
	}
#endif
private:
	T *m_pPoint;
	LONG *m_pnReference;
};