// file:    primes.java
// author:  Robert Keller
// purpose: test lazy evaluation using primes
// To test main use: java -cs primes

import polya.*;
import java.io.*;
import java.util.*;

// squares does not reuse the Growable, although it could in principal

class primes
  {
  static public Polylist all = 
    Polylist.cons(new Long(2), new Incremental(new oddprimes()));

  static public void main(String []arg)
    {
    int numberToPrint = 1000;

    System.out.println(all.prefix(numberToPrint));
    }
  }


// oddprimes is the Polylist of primes (3 5 7 11 ... )

class oddprimes extends Growable
  {
  long n;

  oddprimes()
    {
    n = 3;
    }

  public Object grow()
    {
  loop:
    for( ; ; n+=2 )
      {
      for( Enumeration e = primes.all.elements(); ; )
        {
        long trial = (((Long)(e.nextElement())).longValue());
        if( n % trial == 0 )
          {
          continue loop;
          }
        if( trial*trial > n )
          break loop;
        }
      }
    Long first = new Long(n);
    n+=2;
    return Polylist.cons(first, new Incremental(this));
    }
  }