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#ifndef SHARED_PTR_H
#define SHARED_PTR_H
#include <stdexcept>
/**
* EXAMPLE IMPLEMENTATION! DO NOT EVEN THINK TO USE!
*/
template <class T>
class shared_ptr
{
class holder
{
public:
holder()
: p(0),
counter(1)
{
}
holder(T* t)
: p(t),
counter(1)
{
}
~holder()
{
delete p;
}
T* p;
int counter;
private:
holder& operator=(const holder&);
holder(const holder&);
};
holder* h_;
public:
~shared_ptr()
{
if (--h_->counter == 0)
{
delete h_;
}
}
shared_ptr()
: h_(new holder())
{
}
shared_ptr(T* t)
: h_(new holder(t))
{
}
shared_ptr(const shared_ptr& rhl)
: h_(rhl.h_)
{
++h_->counter;
}
shared_ptr& operator=(const shared_ptr& rhl)
{
if (this == &rhl)
{
return *this;
}
if (--h_->counter == 0)
{
delete h_;
}
h_ = rhl.h_;
++h_->counter;
return *this;
}
shared_ptr& operator=(T* t)
{
if (--h_->counter == 0)
{
delete h_;
}
h_ = new holder(t);
return *this;
}
T* get() const
{
return h_->p;
}
T* operator ->() const
{
if (h_->p == 0)
{
throw std::runtime_error("null pointer dereferenced");
}
return h_->p;
}
void reset(T* t = 0)
{
if (--h_->counter == 0)
{
delete h_;
}
h_ = new holder(t);
}
int count() const
{
return h_->counter;
}
};
#endif
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