package schemeFW;

/**
 * Represents a non-empty list.
 * Implemented as a composite.
 * @author Dung X. Nguyen
 * @author Dung X. Nguyen
 * @author Stephen B. Wong
 * @version 1.1
 * @since 09/10/01
 * @Custom Copyright 2001 -All rights reserved
 */
public class NEList implements INEList {
    /**
     * This <code>NEList</code>'s first.
     */
    private Object _first;

    /**
     * This <code>NEList</code>'s rest
     * @SBGen Variable (,,,64)
     */
    private IList _rest;

    /**
     * Initializes this <code>NEList</code> to the given first and rest.
     * @param dat the first data element of this <code>NEList</code>.
     * @param tail the rest of this AList.
     */
    public NEList(Object dat, IList tail) {
        _first = dat;
        _rest = tail;
    }

    /**
     * Accessor method for this <code>NEList</code>'s first.
     * @return <code>Object</code> the first element of this <code>NEList</code>.
     */
    public Object getFirst() {
        return _first;
    }

    /**
     * Accessor method for this <code>NEList</code>'s rest.
     * @return <code>IList</code> the rest of this <code>NEList</code>.
     */
    public IList getRest() {
        return _rest;
    }

    /**
     * Calls the <code>nonEmptyCase()</code> method of the supplied IListAlgo
     * with the supplied input parameter.
     * @param algo The visitor algorithm to be executed.
     * @param inp input to be handed to algo's <code>nonEmptyCase()</code>.
     * @return <code>Object</code> output of algo's <code>nonEmptyCase()</code>.
     */
    public Object execute(IListAlgo algo, Object inp) {
        return algo.nonEmptyCase(this, inp);
    }
}