    001package org.cpsolver.studentsct.constraint;
    002
    003import java.util.Set;
    004
    005import org.cpsolver.ifs.assignment.Assignment;
    006import org.cpsolver.ifs.model.GlobalConstraint;
    007import org.cpsolver.studentsct.model.CourseRequest;
    008import org.cpsolver.studentsct.model.Enrollment;
    009import org.cpsolver.studentsct.model.Request;
    010import org.cpsolver.studentsct.model.Section;
    011
    012
    013/**
    014 * Required sections constraint. This global constraint ensures that no enrollment
    015 * containing a prohibited section (using {@link CourseRequest#isRequired(Section)}) is used.
    016 *
    017 * @author  Tomáš Müller
    018 * @version StudentSct 1.3 (Student Sectioning)<br>
    019 *          Copyright (C) 2014 Tomáš Müller<br>
    020 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    021 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    022 * <br>
    023 *          This library is free software; you can redistribute it and/or modify
    024 *          it under the terms of the GNU Lesser General Public License as
    025 *          published by the Free Software Foundation; either version 3 of the
    026 *          License, or (at your option) any later version. <br>
    027 * <br>
    028 *          This library is distributed in the hope that it will be useful, but
    029 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    030 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    031 *          Lesser General Public License for more details. <br>
    032 * <br>
    033 *          You should have received a copy of the GNU Lesser General Public
    034 *          License along with this library; if not see
    035 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    036 */
    037public class RequiredSections extends GlobalConstraint<Request, Enrollment> {
    038
    039    /**
    040     * A given enrollment is conflicting, if there is a section that
    041     * is cancelled.
    042     *
    043     * @param enrollment {@link Enrollment} that is being considered
    044     * @param conflicts all computed conflicting requests are added into this set
    045     */
    046    @Override
    047    public void computeConflicts(Assignment<Request, Enrollment> assignment, Enrollment enrollment, Set<Enrollment> conflicts) {
    048        if (inConflict(assignment, enrollment))
    049            conflicts.add(enrollment);
    050    }
    051
    052    /**
    053     * A given enrollment is conflicting, if there is a section that
    054     * is cancelled.
    055     *
    056     * @param enrollment {@link Enrollment} that is being considered
    057     * @return true, if the enrollment does not follow a reservation that must be used
    058     */
    059    @Override
    060    public boolean inConflict(Assignment<Request, Enrollment> assignment, Enrollment enrollment) {
    061        // exclude free time requests
    062        if (enrollment.getConfig() == null) return false;
    063
    064        // check all sections of the given enrollment
    065        CourseRequest cr = (CourseRequest)enrollment.variable();
    066        for (Section section: enrollment.getSections())
    067            if (!cr.isRequired(section)) return true;
    068
    069        return false;
    070    }
    071
    072    @Override
    073    public String toString() {
    074        return "RequiredSections";
    075    }
    076}