package lrs.visitor;

import lrs.*;

/**
* Makes the host share the same head node with the input list.
* The input list does not change.
* @author DXN
* @since 03/25/05
*/
public class Share implements IAlgo {
    public final static Share Singleton = new Share ();
    private Share() {
    }

    /**
     * @param other [0] a LRStruct;
     * @return null
     */
    public Object emptyCase(LRStruct host, Object... other) {
        return assign(host, (LRStruct)other[0]);
    }

    /**
     * @param other [0] a LRStruct;
     * @return null
     */
    public Object nonEmptyCase(LRStruct host, Object... other) {
        return assign(host, (LRStruct)other[0]);
    }

    private Object assign (LRStruct lhs, LRStruct rhs) {
        lhs.insertFront(null);
        lhs.setRest(rhs);
        lhs.removeFront();
        return null;
    }
}