    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.Enrollment;
    008import org.cpsolver.studentsct.model.Request;
    009
    010/**
    011 * Fix initial assignment constraint. This global constraint checks that the
    012 * conflicts that have been computed so far (by other global constraints earlier
    013 * in the list) do not create a conflict with an initial assignment. This constraint
    014 * is to be used only when MPP is enabled and it is to be last global constraint
    015 * in the list.
    016 *
    017 * @author  Tomáš Müller
    018 * @version StudentSct 1.3 (Student Sectioning)<br>
    019 *          Copyright (C) 2007 - 2015 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 FixInitialAssignments extends GlobalConstraint<Request, Enrollment> {
    038
    039    /**
    040     * If there is a conflict that is MPP (method {@link Request#isMPP()} returns true)
    041     * and equal to the initial assignment (returned by {@link Request#getInitialAssignment()}),
    042     * the given enrollment is put into the conflicts.
    043     */
    044    @Override
    045    public void computeConflicts(Assignment<Request, Enrollment> assignment, Enrollment enrollment, Set<Enrollment> conflicts) {
    046        for (Enrollment conflict: conflicts)
    047            if (conflict.getRequest().isMPP() && conflict.equals(conflict.getRequest().getInitialAssignment())) {
    048                conflicts.add(enrollment);
    049                return;
    050            }
    051    }
    052}