参照カウントの単純な実装

class DataSource
{
private:
	volatile unsigned int *m_pICount;
	double *m_pData;

public:
	DataSource(double *pData);
	~DataSource();
	DataSource(const DataSource &ds);
	DataSource& operator =(const DataSource &ds);
	bool operator ==(const DataSource &ds) const;
	bool operator !=(const DataSource &ds) const;

private:
	void release();
};

DataSource::DataSource(double *pData): m_pICount(new unsigned int(1)), m_pData(pData)
{
}

DataSource::~DataSource()
{
	release();
}

DataSource::DataSource(const DataSource &ds): m_pICount(ds.m_pICount), m_pData(ds.m_pData)
{
	if(*this == ds)
		return;

	++(*m_pICount);
}

DataSource& DataSource::operator =(const DataSource &ds)
{
	if(*this == ds)
		return *this;

	this->release();
	m_pData = ds.m_pData;
	m_pICount = ds.m_pICount;
	++(*m_pICount);

	return *this;
}

bool DataSource::operator ==(const DataSource &ds) const
{
	return (m_pICount == ds.m_pICount && m_pData == ds.m_pData);
}

bool DataSource::operator !=(const DataSource &ds) const
{
	return (m_pICount != ds.m_pICount);
}

void DataSource::release()
{
	if(0 == --(*m_pICount))
	{
		delete m_pICount;
		delete m_pData;

		m_pICount = NULL;
		m_pData = NULL;
	}
}