001 package net.sf.cpsolver.coursett.model;
002
003 import net.sf.cpsolver.ifs.model.Constraint;
004 import net.sf.cpsolver.ifs.model.ModelListener;
005 import net.sf.cpsolver.ifs.model.Value;
006 import net.sf.cpsolver.ifs.model.Variable;
007
008 /**
009 * On fly student sectioning.
010 * <br><br>
011 * In this mode, students are resectioned after each iteration, but only between classes that are affected by the iteration.
012 * This slows down the solver, but it can dramatically improve results in the case when there is more stress put on student conflicts (e.g., Woebegon College example).
013 *
014 * <br><br>
015 * Parameters:
016 * <table border='1'><tr><th>Parameter</th><th>Type</th><th>Comment</th></tr>
017 * <tr><td>OnFlySectioning.Enabled</td><td>{@link Boolean}</td><td>Enable on fly sectioning (if enabled, students will be resectioned after each iteration)</td></tr>
018 * <tr><td>OnFlySectioning.Recursive</td><td>{@link Boolean}</td><td>Recursively resection lectures affected by a student swap</td></tr>
019 * <tr><td>OnFlySectioning.ConfigAsWell</td><td>{@link Boolean}</td><td>Resection students between configurations as well</td></tr>
020 * </table>
021 *
022 * @version
023 * CourseTT 1.1 (University Course Timetabling)<br>
024 * Copyright (C) 2006 Tomáš Müller<br>
025 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
026 * Lazenska 391, 76314 Zlin, Czech Republic<br>
027 * <br>
028 * This library is free software; you can redistribute it and/or
029 * modify it under the terms of the GNU Lesser General Public
030 * License as published by the Free Software Foundation; either
031 * version 2.1 of the License, or (at your option) any later version.
032 * <br><br>
033 * This library is distributed in the hope that it will be useful,
034 * but WITHOUT ANY WARRANTY; without even the implied warranty of
035 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
036 * Lesser General Public License for more details.
037 * <br><br>
038 * You should have received a copy of the GNU Lesser General Public
039 * License along with this library; if not, write to the Free Software
040 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
041 */
042
043 public class OnFlySectioning implements ModelListener {
044 private FinalSectioning iFinalSectioning;
045 private boolean iRecursive = true;
046 private boolean iConfigAsWell = false;
047
048 /**
049 * Constructor
050 * @param model timetabling model
051 */
052 public OnFlySectioning(TimetableModel model) {
053 iFinalSectioning = new FinalSectioning(model);
054 }
055
056 public void variableAdded(Variable variable) {}
057
058 public void variableRemoved(Variable variable) {}
059
060 public void constraintAdded(Constraint constraint) {}
061
062 public void constraintRemoved(Constraint constraint) {}
063
064 public void beforeAssigned(long iteration, Value value) {}
065
066 public void beforeUnassigned(long iteration, Value value) {}
067
068 /**
069 * {@link FinalSectioning#resection(Lecture, boolean, boolean)} is called when given iteration number
070 * is greater than zero.
071 */
072 public void afterAssigned(long iteration, Value value) {
073 if (iteration>0)
074 iFinalSectioning.resection((Lecture)value.variable(), iRecursive, iConfigAsWell);
075 }
076
077 public void afterUnassigned(long iteration, Value value) {}
078
079 /**
080 * Initialization
081 */
082 public boolean init(net.sf.cpsolver.ifs.solver.Solver solver) {
083 iRecursive = solver.getProperties().getPropertyBoolean("OnFlySectioning.Recursive", true);
084 iConfigAsWell = solver.getProperties().getPropertyBoolean("OnFlySectioning.ConfigAsWell", false);
085 return true;
086 }
087 }