    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;
    010
    011/**
    012 * Fixed assignment constraint. This global constraint checks that the
    013 * conflicts that have been computed so far (by other global constraints earlier
    014 * in the list) do not create a conflict with a fixed assignment. This constraint
    015 * is to be used only when there are fixed course requests and it is to be last global constraint
    016 * in the list.
    017 *
    018 * @author  Tomáš Müller
    019 * @version StudentSct 1.3 (Student Sectioning)<br>
    020 *          Copyright (C) 2007 - 2015 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 */
    038public class FixedAssignments extends GlobalConstraint<Request, Enrollment> {
    039
    040    /**
    041     * If there is a conflict that is fixed (method {@link CourseRequest#isFixed()} returns true)
    042     * and equal to the initial assignment (returned by {@link CourseRequest#getFixedValue()}),
    043     * the given enrollment is put into the conflicts.
    044     */
    045    @Override
    046    public void computeConflicts(Assignment<Request, Enrollment> assignment, Enrollment enrollment, Set<Enrollment> conflicts) {
    047        for (Enrollment conflict: conflicts) {
    048            if (conflict.getRequest() instanceof CourseRequest) {
    049                CourseRequest cr = (CourseRequest)conflict.getRequest();
    050                if (cr.isFixed() && conflict.equals(cr.getFixedValue())) {
    051                    conflicts.add(enrollment);
    052                    return;
    053                }
    054            }
    055        }
    056    }
    057}