package OOscheme;

/**
 * Concrete implementation of the empty list interface, IEmptyList.
 * Provides concrete code for the execute method: simply calls the emptyCase
 * method of the IListAlgo parameter, passing to this method itself as the host
 * and the given input Object as the input.
 * Note the class is not public in order to hide from all client code outside
 * of the OOscheme package.
 * @author Dung X. Nguyen
 * @since Copyright 2002 by DXN - All rights reserved
 */
public class EmptyList implements IEmptyList {

    /**
     * Singleton Design Pattern.
     */
    public final static EmptyList Singleton = new EmptyList();
    private EmptyList() {
    }

    /**
     * Calls the empty case of the algorithm algo, passing to it itself as
     * the host parameter and the given inp as the input parameter.
     * This method is marked as final to prevent all subclasses from
     * overriding it.  Finalizing a method also allows the compiler to generate
     * more efficient calling code.
     */
    final public Object execute(IListAlgo algo, Object... inp) {
        return algo.emptyCase(this, inp);
    }
}