package list;

class EmptyList extends AList
{
    public final static EmptyList Singleton = new EmptyList ();

    private EmptyList()
    {
    }
   
    public Object getFirst()
    {
	throw new java.util.NoSuchElementException ("Empty has no element.");
    }

    public AList getRest()
    {
	throw new java.util.NoSuchElementException ("Empty has no tail.");
    }

    /**
     * @param input 
     */
    public Object execute(IListAlgo algo, Object input)
    {
	return algo.forEmpty (this, input);
    }
}