package org.ofbiz.rules.parse;


import java.util.*;


/**
 * <p><b>Title:</b> Track
 * <p><b>Description:</b> None
 * <p>Copyright (c) 1999 Steven J. Metsker.
 * <p>Copyright (c) 2001 The Open For Business Project - www.ofbiz.org
 *
 * <p>Permission is hereby granted, free of charge, to any person obtaining a
 *  copy of this software and associated documentation files (the "Software"),
 *  to deal in the Software without restriction, including without limitation
 *  the rights to use, copy, modify, merge, publish, distribute, sublicense,
 *  and/or sell copies of the Software, and to permit persons to whom the
 *  Software is furnished to do so, subject to the following conditions:
 *
 * <p>The above copyright notice and this permission notice shall be included
 *  in all copies or substantial portions of the Software.
 *
 * <p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 *  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 *  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 *  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT
 *  OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
 *  THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * <br>
 * A Track is a sequence that throws a <code>
 * TrackException</code> if the sequence begins but
 * does not complete.
 *
 * @author Steven J. Metsker
 * @version 1.0
 */

public class Track extends Sequence {

    /**
     * Constructs a nameless Track.
     */
    public Track() {}

    /**
     * Constructs a Track with the given name.
     *
     * @param    name    a name to be known by
     */
    public Track(String name) {
        super(name);
    }

    /**
     * Given a collection of assemblies, this method matches
     * this track against all of them, and returns a new
     * collection of the assemblies that result from the
     * matches.
     *
     * If the match begins but does not complete, this method
     * throws a <code>TrackException</code>.
     *
     * @return   a List of assemblies that result from matching
     *           against a beginning set of assemblies
     *
     * @param in a vector of assemblies to match against
     *
     */
    public List match(List in) {
        boolean inTrack = false;
        List last = in;
        List out = in;
        Enumeration e = Collections.enumeration(subparsers);

        while (e.hasMoreElements()) {
            Parser p = (Parser) e.nextElement();

            out = p.matchAndAssemble(last);
            if (out.isEmpty()) {
                if (inTrack) {
                    throwTrackException(last, p);
                }
                return out;
            }
            inTrack = true;
            last = out;
        }
        return out;
    }

    /**
     * Throw an exception showing how far the match had
     * progressed, what it found next, and what it was
     * expecting.
     */
    protected void throwTrackException(List previousState, Parser p) {

        Assembly best = best(previousState);
        String after = best.consumed(" ");

        if (after.equals("")) {
            after = "-nothing-";
        }

        String expected = p.toString();

        Object next = best.peek();
        String found =
            (next == null) ? "-nothing-" : next.toString();

        throw new TrackException(after, expected, found);
    }
}