    001package org.cpsolver.exam.neighbours;
    002
    003import java.util.Iterator;
    004import java.util.Set;
    005
    006import org.cpsolver.exam.model.Exam;
    007import org.cpsolver.exam.model.ExamModel;
    008import org.cpsolver.exam.model.ExamPeriodPlacement;
    009import org.cpsolver.exam.model.ExamPlacement;
    010import org.cpsolver.exam.model.ExamRoomPlacement;
    011import org.cpsolver.exam.model.ExamRoomSharing;
    012import org.cpsolver.ifs.assignment.Assignment;
    013import org.cpsolver.ifs.heuristics.NeighbourSelection;
    014import org.cpsolver.ifs.model.Neighbour;
    015import org.cpsolver.ifs.solution.Solution;
    016import org.cpsolver.ifs.solver.Solver;
    017import org.cpsolver.ifs.util.DataProperties;
    018import org.cpsolver.ifs.util.ToolBox;
    019
    020
    021/**
    022 * A new period is selected for a randomly selected exam. It tries to use the
    023 * current set of rooms, if it is possible (exam is assigned, rooms are
    024 * available and not used during the new period). Otherwise, rooms are selected
    025 * using {@link Exam#findBestAvailableRooms(Assignment, ExamPeriodPlacement)}. <br>
    026 * <br>
    027 *
    028 * @version ExamTT 1.3 (Examination Timetabling)<br>
    029 *          Copyright (C) 2008 - 2014 Tomáš Müller<br>
    030 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    031 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    032 * <br>
    033 *          This library is free software; you can redistribute it and/or modify
    034 *          it under the terms of the GNU Lesser General Public License as
    035 *          published by the Free Software Foundation; either version 3 of the
    036 *          License, or (at your option) any later version. <br>
    037 * <br>
    038 *          This library is distributed in the hope that it will be useful, but
    039 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    040 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    041 *          Lesser General Public License for more details. <br>
    042 * <br>
    043 *          You should have received a copy of the GNU Lesser General Public
    044 *          License along with this library; if not see
    045 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    046 */
    047public class ExamTimeMove implements NeighbourSelection<Exam,ExamPlacement> {
    048    private boolean iCheckStudentConflicts = false;
    049    private boolean iCheckDistributionConstraints = true;
    050
    051    /**
    052     * Constructor
    053     * @param properties problem properties
    054     */
    055    public ExamTimeMove(DataProperties properties) {
    056        iCheckStudentConflicts = properties.getPropertyBoolean("ExamTimeMove.CheckStudentConflicts", iCheckStudentConflicts);
    057        iCheckDistributionConstraints = properties.getPropertyBoolean("ExamTimeMove.CheckDistributionConstraints", iCheckDistributionConstraints);
    058    }
    059
    060    /**
    061     * Initialization
    062     */
    063    @Override
    064    public void init(Solver<Exam,ExamPlacement> solver) {}
    065
    066    /**
    067     * Select an exam randomly,
    068     * select an available period randomly (if it is not assigned),
    069     * use rooms if possible, select rooms using {@link Exam#findBestAvailableRooms(Assignment, ExamPeriodPlacement)} if not (exam is unassigned, a room is not available or used).
    070     */
    071    @Override
    072    public Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution) {
    073        ExamModel model = (ExamModel)solution.getModel();
    074        Assignment<Exam, ExamPlacement> assignment = solution.getAssignment();
    075        ExamRoomSharing sharing = model.getRoomSharing();
    076        Exam exam = ToolBox.random(model.variables());
    077        ExamPlacement placement = assignment.getValue(exam);
    078        int px = ToolBox.random(exam.getPeriodPlacements().size());
    079        for (int p=0;p<exam.getPeriodPlacements().size();p++) {
    080            ExamPeriodPlacement period = exam.getPeriodPlacements().get((p+px)%exam.getPeriodPlacements().size());
    081            if (placement!=null && placement.getPeriod().equals(period)) continue;
    082            if (iCheckStudentConflicts && exam.countStudentConflicts(assignment, period)>0) continue;
    083            if (iCheckDistributionConstraints && !exam.checkDistributionConstraints(assignment, period)) continue;
    084            if (placement!=null) {
    085                boolean ok = true;
    086                if (sharing != null && placement.getRoomPlacements().size() == 1) {
    087                    ExamRoomPlacement room = placement.getRoomPlacements().iterator().next();
    088                    ok = room.isAvailable(period.getPeriod()) && !sharing.inConflict(exam, room.getRoom().getPlacements(assignment, period.getPeriod()), room.getRoom());
    089                } else {
    090                    for (Iterator<ExamRoomPlacement> i=placement.getRoomPlacements().iterator();i.hasNext();) {
    091                        ExamRoomPlacement room = i.next();
    092                        if (!room.isAvailable(period.getPeriod()) || !room.getRoom().getPlacements(assignment, period.getPeriod()).isEmpty()) {
    093                            ok = false; break;
    094                        }
    095                    }
    096                }
    097                if (ok)
    098                    return new ExamSimpleNeighbour(assignment, new ExamPlacement(exam, period, placement.getRoomPlacements()));
    099            }
    100            Set<ExamRoomPlacement> rooms = exam.findBestAvailableRooms(assignment, period);
    101            if (rooms==null) continue;
    102            return new ExamSimpleNeighbour(assignment, new ExamPlacement(exam, period, rooms));
    103        }
    104        return null;
    105    }
    106}