icptrholder_cxx.h

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#ifndef ICPTRHOLDER_CXX_H
#define ICPTRHOLDER_CXX_H
 
#include <cassert>
 
template < class T > class ICPointerHolder
{
public:
    ICPointerHolder()
        : ptr(0)
    {
    }
 
    ICPointerHolder(T *p)
        : ptr(p)
    {
    }
 
    // copy constructor to support assignment
    ICPointerHolder(const ICPointerHolder &ip)
        : ptr(ip.ptr)
    {
        // We need to transfer ownership of ptr to this object by setting
        // ip's ptr to null. Otherwise, ptr will de deleted twice.
        // const ugliness requires us to do the const_cast.
        ICPointerHolder *ipp = const_cast < ICPointerHolder * >(&ip);
 
        ipp->ptr = 0;
    };
 
    ~ICPointerHolder()
    {
        release();
    }
 
    ICPointerHolder &operator=(T *p)
    {
        this->release();
        ptr = p;
        return *this;
    }
 
    ICPointerHolder &operator=(ICPointerHolder &p)
    {
        this->release();
        ptr = p.ptr;    // this transfer ownership of the pointer
        p.ptr = 0;      // set it to null so the pointer won't get delete twice.
        return *this;
    }
 
    bool operator!=(T *p)
    {
        return (ptr != p);
    }
 
    bool operator==(T *p)
    {
        return (ptr == p);
    }
 
    operator  T *() const
    {
        return ptr;
    }
 
    T *operator->() const
    {
        assert(ptr);
        return ptr;
    }
 
    T &operator*()
    {
        assert(ptr);
        return *ptr;
    }
 
private:
    void release()
    {
        if (ptr != 0) {
            ptr->detach();
            delete ptr;
 
            ptr = 0;
        }
    }
 
    T *ptr;
};
 
#endif