001package org.cpsolver.ifs.solver;
002
003import org.cpsolver.ifs.assignment.Assignment;
004import org.cpsolver.ifs.model.Neighbour;
005import org.cpsolver.ifs.model.Value;
006import org.cpsolver.ifs.model.Variable;
007
008/**
009 * IFS Solver Listener.
010 * 
011 * @see Solver
012 * 
013 * @version IFS 1.3 (Iterative Forward Search)<br>
014 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
015 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
016 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
017 * <br>
018 *          This library is free software; you can redistribute it and/or modify
019 *          it under the terms of the GNU Lesser General Public License as
020 *          published by the Free Software Foundation; either version 3 of the
021 *          License, or (at your option) any later version. <br>
022 * <br>
023 *          This library is distributed in the hope that it will be useful, but
024 *          WITHOUT ANY WARRANTY; without even the implied warranty of
025 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
026 *          Lesser General Public License for more details. <br>
027 * <br>
028 *          You should have received a copy of the GNU Lesser General Public
029 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
030 *
031 * @param <V> Variable
032 * @param <T> Value
033 **/
034public interface SolverListener<V extends Variable<V, T>, T extends Value<V, T>> {
035
036    /**
037     * A variable was selected
038     * 
039     * @param assignment current assignment
040     * @param iteration
041     *            current iteration
042     * @param variable
043     *            selected variable
044     * @return if false is returned the variable will be discarded (search continues with the next variable selection)
045     */
046    public boolean variableSelected(Assignment<V, T> assignment, long iteration, V variable);
047
048    /**
049     * A value was selected
050     * 
051     * @param assignment current assignment
052     * @param iteration
053     *            current iteration
054     * @param variable
055     *            selected variable
056     * @param value
057     *            selected variable
058     * @return if false is returned the selected value is not assigned
059     */
060    public boolean valueSelected(Assignment<V, T> assignment, long iteration, V variable, T value);
061
062    /**
063     * A neighbour was selected
064     * 
065     * @param assignment current assignment
066     * @param iteration
067     *            current iteration
068     * @param neighbour
069     *            neighbour
070     * @return if false is returned the selected neighbour is not assigned
071     */
072    public boolean neighbourSelected(Assignment<V, T> assignment, long iteration, Neighbour<V, T> neighbour);
073    
074    /**
075     * Called when {@link ParallelSolver} failed to assign the given neighbour
076     * 
077     * @param assignment current assignment
078     * @param iteration
079     *            current iteration
080     * @param neighbour
081     *            neighbour
082     */
083    public void neighbourFailed(Assignment<V, T> assignment, long iteration, Neighbour<V, T> neighbour);
084
085}