package brs.visitor;
import brs.*;

/**
 * Add all the numbers in a tree in in-order.
 * @author DXN
 */
public class InOrderAdd implements IVisitor {
    public static final InOrderAdd Singleton = new InOrderAdd();    
    private InOrderAdd() {
    }
    
    public Object emptyCase(BiTree host, Object nu) {
        return 0; 
    }

    public Object nonEmptyCase(BiTree host, Object nu) {
        Integer left = (Integer)host.getLeftSubTree().execute(this, null);
        Integer root = (Integer)host.getRootDat();
        Integer right = (Integer)host.getRightSubTree().execute(this, null);
        return left + root + right;
    }
}