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ref.h

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#ifndef REF_H
#define REF_H


template<class T>
class ref {
friend T;
public:
  ref(): t_(0), n_(new unsigned int(1)) {}
  ref(const ref<T>& r): t_(r.t_), n_(r.n_) { ++*n_; }
  ~ref() { if (--*n_) return; delete t_; delete n_; }

  operator  bool() const  { return (t_!=0); }
  T&  operator*() const { return *t_; }
  T*  operator->() const { return t_; }    
  ref<T>&  operator=(const ref<T>& r) { 
             if (this==&r) return *this;
             if (--*n_==0) { 
               delete t_; delete n_;
               }
             t_ = r.t_;  n_=r.n_; ++*n_; return *this;  
             }
  bool operator==(const ref<T>& r) const {
        if (t_ == r.t_) return true;
        if (t_)
          if (r.t_)
            return (*t_ == *r);
          else
            return false;
        // r.t_ != t_ == 0
        return false;
        }
  bool operator<(const ref<T>& r) const {
        // null is minimal element in this implementation
        if (t_ == r.t_) return false;
        if (t_)
          if (r.t_)
            return (*t_ < *r);
          else
            return false;
        // t_ == 0, r.t_ != 0
        return true;
        }
protected:
  ref(T* t): t_(t), n_(new unsigned int(1)) {}
private:
  T*            t_;
  unsigned int* n_;
};

#endif

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FSM [ August, 2001]