package lrs.visitor;
import lrs.*;

/**
 * Determines whether or not an Object is in the host LRStruct.
 * @author Dung X. Nguyen - Copyright 2005 - All rights reserved.
 */
public class Contain implements IAlgo {
    public final static Contain Singleton = new Contain();
    private Contain() {
    }
    
    /**
     */
    public Object emptyCase(LRStruct host, Object... nu) {
        return false;
    }
    
    /**
     */
    public Object nonEmptyCase(LRStruct host, Object... inp) {
        return inp[0].equals(host.getFirst())? 
            true: 
            host.getRest().execute(this, inp[0]); 
    }
}