package list.visitor;
import list.*;

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

    private Append()
    {
    }

    /**
     * @param input receives a list.
     * Returns the input list
     */
    public Object forEmpty(AList host, Object input)
    {
	return input;
    }
    
     /**
     * Returns the appended lists.
     */
   public Object forNonEmpty(AList host, Object input)
    {
	if ((AList)input == ListFactory.Singleton.makeEmptyList())
	    {
		return host;
	    }
	else
	    {
		return ListFactory.Singleton.makeNEList(host.getFirst(), (AList)host.getRest().execute(this, input));
	    }
    }
}