basic_shared_pointer.h

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**  Copyright Fougue (1 Mar. 2011)
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#pragma once

#include <cstddef>

namespace cpp {

template <typename T>
class BasicSharedPointer
{
public:
    BasicSharedPointer(T* data = NULL);
    BasicSharedPointer(const BasicSharedPointer<T>& other);
    ~BasicSharedPointer();

    T& operator*() const;
    T* operator->() const;
    T* data() const;

    bool isNull() const;

    BasicSharedPointer<T>& operator=(const BasicSharedPointer<T>& other);

private:
    void addRef();
    void releaseRef();

    T* m_data;
    unsigned* m_refCount;
};

//
// Implementation
//

template<typename T>
BasicSharedPointer<T>::BasicSharedPointer(T* data)
    : m_data(data),
      m_refCount(new unsigned(1))
{
}

template<typename T>
BasicSharedPointer<T>::BasicSharedPointer(const BasicSharedPointer<T>& other)
    : m_data(other.m_data),
      m_refCount(other.m_refCount)
{
    this->addRef();
}

template<typename T>
BasicSharedPointer<T>::~BasicSharedPointer()
{
    this->releaseRef();
}

template<typename T>
T& BasicSharedPointer<T>::operator*() const
{
    return *m_data;
}

template<typename T>
T* BasicSharedPointer<T>::operator->() const
{
    return m_data;
}

template<typename T>
T* BasicSharedPointer<T>::data() const
{
    return m_data;
}

template<typename T>
bool BasicSharedPointer<T>::isNull() const
{
    return m_data == NULL;
}

template<typename T>
BasicSharedPointer<T>& BasicSharedPointer<T>::operator=(const BasicSharedPointer<T>& other)
{
    if (this != &other) {
        m_data = other.m_data;
        m_refCount = other.m_refCount;
        this->addRef();
    }
    return *this;
}

template<typename T>
void BasicSharedPointer<T>::addRef()
{
    ++(*m_refCount);
}

template<typename T>
void BasicSharedPointer<T>::releaseRef()
{
    --(*m_refCount);
    if (*m_refCount == 0) {
        delete m_data;
        delete m_refCount;
        m_data = NULL;
        m_refCount = NULL;
    }
}

} // namespace cpp