package listFW.visitor;

import listFW.*;
import listFW.factory.*;

public class RunSum implements IListAlgo {

    private IListFactory _lf;

    public RunSum(IListFactory lf) {
        _lf = lf;
    }

    public Object emptyCase(IEmptyList host, Object... nu) {
        return _lf.makeEmptyList();
    }

    public Object nonEmptyCase(INEList host, Object... nu) {
        IList list = (IList)host.getRest().execute(new IListAlgo() {

            public Object emptyCase(IEmptyList h, Object... nu) {
                return _lf.makeEmptyList();
            }

            public Object nonEmptyCase(INEList h, Object... acc) {
                int sum = (Integer)h.getFirst() +(Integer)acc[0];
                IList l = (IList)h.getRest().execute(this, sum);
                l = _lf.makeNEList(sum, l);
                return l;
            }
        }, host.getFirst());
        list = _lf.makeNEList(host.getFirst(), list);
        return list;
    }
}