package listFW.visitor;

import listFW.*;

/**
 * Sums all the elements in the host list, assuming it contains all Integer.
 * @author DXN
 */
public class Sum implements IListAlgo {
    public Object emptyCase(IEmptyList host, Object inp) {
        return new Integer(0);
    }

    public Object nonEmptyCase(INEList host, Object inp) {
        int f = ((Integer)host.getFirst()).intValue();
        int r = ((Integer)host.getRest().execute(this, null)).intValue();
        return new Integer(f + r);
    }
}