package scheme;
/**
 * Represents a non-empty list.
 * Implemented as a composite.
 *
 * @author Dung X. Nguyen
 * @version 1.0
 * @since 09/10/00
 * @Custom Copyright 2000 -All rights reserved
 */
public class NEList extends AList {
    private Object _first;
    private AList _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, AList tail) {
        _first = dat;
        _rest = tail;
    }

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

    /**
     * @return <code>AList</code> the rest of this <code>NEList</code>.
     */
    public AList getRest() {
        return _rest;
    }

    /**
     * Returns the String representation of first data element followed by
     * the String representation of the rest.
     * @return String != null, != "".
     */
    public String toString() {
        return _first.toString () + " " + _rest.toString();
    }

    /**
     * Returns 1 + the number of elements of the rest.
     * @return int >= 1.
     */
    public int length() {
        return 1 + _rest.length();
    }

    /**
     * Asks the tail for help to compute the length, passing it an accumulated
     * length of 1, and returns the result.
     * @return int >= 1.
     */
    public int getLength() {
        return _rest.helpGetLength (1);
    }

    /**
     * Adds 1 to the accumulated length, passes it down to the tail for help
     * to compute the length, and returns the result.
     * @return int > acc.
     */
    protected int helpGetLength(int acc) {
        return _rest.helpGetLength (acc + 1);
    }

    /**
     * Asks _rest for help to compute the min, passing it the int value of
     * _first as the accumulated min.
     */
    public int getMin() {
        return _rest.helpGetMin(((Integer)_first).intValue());
    }

    /**
    * Computes the smaller of the accumulated min parameter and the value of
    * _first, and passes the result down to the tail for help to compute the min.
    */
    protected int helpGetMin(int accMin) {
        return _rest.helpGetMin(Math.min(((Integer)_first).intValue(), accMin));
    }
}