package lrs.visitor;

import lrs.*;

/**
 * Assumes each element in the host is an LRStruct of Double.
 * Replaces each LRStruct in the host with the average of the numbers
 * it contains.  In the end, the host only contains Doubles representing the
 * average of the original list.
 * @author D. X. Nguyen
 * @version 1.0
 */
public class ReplaceWithAverage implements IAlgo {

    public static final ReplaceWithAverage Singleton = new ReplaceWithAverage();
    private ReplaceWithAverage() {
    }

    public Object emptyCase(LRStruct host, Object inp) {
        return host;
    }

    public Object nonEmptyCase(LRStruct host, Object inp) {
        LRStruct lrs = (LRStruct)host.getFirst();
        Object average = lrs.execute(new Average(), null);
        host.setFirst(average);
        return host.getRest().execute(this, null);
    }
}