package lrs;


/**
 * Represents an abstract algorithm on a LRStruct.  Acts as a visitor to a LRStruct host.
 * @author Dung X. Nguyen  Copyright 2000 - All rights reserved.
 * @since 02/15/00
 * @dependency lrs.LRStruct uses
 */
public interface IAlgo
{
    /**
     * Operates on the LRStruct host when it is empty, given an input object.
     * @param host the LRStruct this IVisitor operates on.
     * @param input input object needed by this IVisitor.
     * @return an appropriate output object.
     */
    public abstract Object nullCase(LRStruct host, Object input);

    /**
     * Operates on the LRStruct host when it is not empty, given an input object.
     * @param host the LRStruct this IVisitor operates on.
     * @param input input object needed by this IVisitor.
     * @return an appropriate output object.
     */
    public abstract Object nonNullCase(LRStruct host, Object input);
}