带引用计数的智能指针

#define DbgPrint(...) printf(__VA_ARGS__)
#define DbgEnter() {DbgPrint("+%s/n",__FUNCSIG__);DbgPrint("+pointer_=0x%x,refcount_=0x%x,*refcount_=0x%x/n",pointer_,refcount_,refcount_==0?0:*refcount_);}
#define DbgLeave() {DbgPrint("+pointer_=0x%x,refcount_=0x%x,*refcount_=0x%x/n",pointer_,refcount_,refcount_==0?0:*refcount_);DbgPrint("-%s/n",__FUNCSIG__);}
//带引用计数的智能指针
template<typename T>
class XSharedPointer
{
public:
    XSharedPointer();
    XSharedPointer(T* t);
    XSharedPointer(const XSharedPointer<T>& t);
    virtual ~XSharedPointer();
    T& operator*();
    T* operator->();
    XSharedPointer<T>& operator=(const XSharedPointer<T>& t);
    XSharedPointer<T>& operator=(const T* t);
    void clear();
protected:
private:
    T* pointer_;
    unsigned int* refcount_;
};
template<typename T>
XSharedPointer<T>::XSharedPointer():refcount_(0),pointer_(0)
{
    DbgEnter();
    pointer_=0;
    refcount_=0;
    DbgLeave();
}

template<typename T>
XSharedPointer<T>::XSharedPointer(T* t):refcount_(0),pointer_(0)
{
    DbgEnter();
    pointer_=t;
    if (t!=0)
    {    
        refcount_=new unsigned int(1);
    }
    else
    {
        refcount_=0;
    }
    DbgLeave();
}

template<typename T>
XSharedPointer<T>::XSharedPointer(const XSharedPointer<T>& t):refcount_(0),pointer_(0)
{
    DbgEnter();
    pointer_=t.pointer_;
    refcount_=t.refcount_;
    if (refcount_!=0)
    {
        (*refcount_)++;
    }
    DbgLeave();
}

template<typename T>
XSharedPointer<T>::~XSharedPointer()
{
    DbgEnter();
    //引用计数-1；若==1则删除指针
    if (refcount_!=0&&(*refcount_)--==1)
    {
        delete pointer_;
        delete refcount_;
        pointer_=0;
        refcount_=0;
    }
    DbgLeave();
}

template<typename T>
T& XSharedPointer<T>::operator *()
{
    DbgEnter();
    DbgLeave();
    return *pointer_;
}
template<typename T>
T* XSharedPointer<T>::operator ->()
{
    DbgEnter();
    DbgLeave();
    return pointer_;
}
template<typename T>
XSharedPointer<T>& XSharedPointer<T>::operator=(const XSharedPointer<T>& t)
{
    DbgEnter();
    if (&t==this)
    {
        return *this;
    }
    if (refcount_!=0&&(*refcount_)--==1)
    {
        delete pointer_;
        delete refcount_;
        pointer_=0;
        refcount_=0;
    }
    refcount_=t.refcount_;
    if (refcount_!=0)
    {
        (*refcount_)++;
    }
    pointer_=t.pointer_;
    DbgLeave();
    return *this;
}
template<typename T>
XSharedPointer<T>& XSharedPointer<T>::operator =(const T* t)
{
    DbgEnter();
    if (refcount_!=0&&(*refcount_)--==1)
    {
        delete pointer_;
        delete refcount_;
        pointer_=0;
        refcount_=0;
    }
    refcount_=new int(1);
    pointer_=t;
    DbgLeave();
    return *this;
}
/* 清除共享指针 */
template<typename T>
void XSharedPointer<T>::clear()
{
    DbgEnter();
    if (refcount_!=0&&(*refcount_)--==1)
    {
        delete pointer_;
        delete refcount_;
    }
    pointer_=0;
    refcount_=0;
    DbgLeave();
}