/*   Eratosthenes' Sieve      */
/*   Data driven discipline   */

/*   File Eratosthenes_data_driven.c  */

#include <iostream.h> 

class Item { 
   protected:
      Item *destination; 
   public:
      virtual void in(int n, Item *src) {} 
   friend class Sieve;
};

class Generator: public Item { 
      int value; 
   public: 
      void start(int maximum){
           while (value<maximum) { destination->in(value++,this);}
      } 
      Generator(Item *dst){destination = dst; value = 2; } 
}; 

class Filter: public Item { 
      int factor; 
   public: 
      void in(int n, Item *src) { 
               if (n%factor) { destination->in(n, this); }
       } 
      Filter(int f, Item *dst){ factor = f; destination = dst; }
}; 

class Sieve: public Item{ 
   public: 
       void in(int n, Item *src) { 
           cout << n << " ";
           src->destination = new Filter(n,this); 
       } 
};

main() {
	Sieve s;
        Generator g(&s);
        int max;
        cout << "Input the upper bound" << '\n';
        cin >> max;
        cout << "These are the prime numbers between " << 2 << " and " << max << '\n';
        g.start(max);
        cout << '\n';
}