    001package org.cpsolver.ifs.solution;
    002
    003import org.cpsolver.ifs.model.Value;
    004import org.cpsolver.ifs.model.Variable;
    005
    006/**
    007 * IFS solution comparator. <br>
    008 * <br>
    009 * The solution comparator compares two solutions: the current solution and the
    010 * best solution found. This comparison can be based on several criteria. For
    011 * example, it can lexicographically order solutions according to the number of
    012 * unassigned variables (smaller number is better) and the number of violated
    013 * soft constraints.
    014 *
    015 * @see Solution
    016 * @see org.cpsolver.ifs.solver.Solver
    017 *
    018 * @author  Tomáš Müller
    019 * @version IFS 1.3 (Iterative Forward Search)<br>
    020 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
    021 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    022 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    023 * <br>
    024 *          This library is free software; you can redistribute it and/or modify
    025 *          it under the terms of the GNU Lesser General Public License as
    026 *          published by the Free Software Foundation; either version 3 of the
    027 *          License, or (at your option) any later version. <br>
    028 * <br>
    029 *          This library is distributed in the hope that it will be useful, but
    030 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    031 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    032 *          Lesser General Public License for more details. <br>
    033 * <br>
    034 *          You should have received a copy of the GNU Lesser General Public
    035 *          License along with this library; if not see
    036 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    037 *
    038 * @param <V> Variable
    039 * @param <T> Value
    040 */
    041public interface SolutionComparator<V extends Variable<V, T>, T extends Value<V, T>> {
    042    /**
    043     * Compares two solutions. Returns true if the given solution is better than
    044     * its best ever found solution (see {@link Solution#saveBest()} and
    045     * {@link Solution#restoreBest()}).
    046     *
    047     * @param currentSolution
    048     *            given solution
    049     * @return true if the given solution is better than the best ever found
    050     *         solution
    051     */
    052    public boolean isBetterThanBestSolution(Solution<V, T> currentSolution);
    053}