package scheme2.visitor;

import scheme2.*;

public class GetLength implements IListAlgo
{
   public final static GetLength Singleton = new GetLength ();

   private GetLength()
   {
   }

	/**
	 * @param host 
	 * @param input 
	 * @return 
	 */
	public Object forEmpty(AListFW host, Object input)
	{

		return new Integer (0);
	}

	/**
	 * @param host 
	 * @param input 
	 * @return 
	 */
	public Object forNonEmpty(AListFW host, Object input)
	{
		return host.getRest ().execute (new HelpGetLen (1), null);
	}

   public static void main (String[] args)
   {
      AListFW p0 = ListFWFactory.Singleton.makeEmptyList();
      AListFW p1 = ListFWFactory.Singleton.makeNEList (new Integer (-5), p0);
      AListFW p2 = ListFWFactory.Singleton.makeNEList (new Integer (3), p1);
      AListFW p3 = ListFWFactory.Singleton.makeNEList (new Integer (0), p2);
      System.out.println ("length of p0 = " + p0.execute(GetLength.Singleton, null));
      System.out.println ("length of p1 = " + p1.execute(GetLength.Singleton, null));
      System.out.println ("length of p2 = " + p2.execute(GetLength.Singleton, null));
      System.out.println ("length of p3 = " + p3.execute(GetLength.Singleton, null));
   }
}