package lrs.visitor;

import lrs.*;
/**
* Reverses the host.
* @author DXN
*/
public class Reverse implements IAlgo
{
   public static final Reverse Singleton = new Reverse ();

   private Reverse ()
   {
   }

	/**
	 */
	public Object forEmpty(LRStruct host, Object input)
	{
		return null;
	}

	/**
	 */
	public Object forNonEmpty(LRStruct host, Object input)
	{
		return host.getRest ().execute (ReverseHelp.Singleton, host);
	}

   public static void main (String[] args)
   {
      LRStruct p = new LRStruct ();
      testVisitor (p, Reverse.Singleton, null);
      p.insertFront(new Integer (-1));
      testVisitor (p, Reverse.Singleton, null);
      p.insertFront (new Integer (3));
      testVisitor (p, Reverse.Singleton, null);
      p.insertFront(new Integer (5));
      testVisitor (p, Reverse.Singleton, null);
      p.insertFront(new Integer (99));
      testVisitor (p, Reverse.Singleton, null);
   }
      
	private static void testVisitor(LRStruct p, IAlgo algo, Object input)
   // NOTE the use of Object.getClass ()!!!
   // Also watch what happens when input == null!!!
	{
      try
      {
         System.out.println (p + " execute " + algo.getClass () + ", " + input + "...");
         System.out.println ("   ---> " + p.execute (algo, input) + " " + p);
      }
      catch (Exception e)
      {
         System.out.println (e);
      }
	}
}