    001package org.cpsolver.instructor.constraints;
    002
    003import java.util.ArrayList;
    004import java.util.List;
    005import java.util.Set;
    006
    007import org.cpsolver.ifs.assignment.Assignment;
    008import org.cpsolver.ifs.model.GlobalConstraint;
    009import org.cpsolver.ifs.util.ToolBox;
    010import org.cpsolver.instructor.model.Instructor.Context;
    011import org.cpsolver.instructor.model.TeachingAssignment;
    012import org.cpsolver.instructor.model.TeachingRequest;
    013
    014/**
    015 * Instructor Constraint. This is the main constraint of the problem, ensuring that an instructor gets a consistent list of
    016 * assignments. It checks for instructor availability, maximal load, time conflicts, and whether the given assignments are of the same
    017 * course (if desired).
    018 *
    019 * @author  Tomáš Müller
    020 * @version IFS 1.3 (Instructor Sectioning)<br>
    021 *          Copyright (C) 2016 Tomáš Müller<br>
    022 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    023 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    024 * <br>
    025 *          This library is free software; you can redistribute it and/or modify
    026 *          it under the terms of the GNU Lesser General Public License as
    027 *          published by the Free Software Foundation; either version 3 of the
    028 *          License, or (at your option) any later version. <br>
    029 * <br>
    030 *          This library is distributed in the hope that it will be useful, but
    031 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    032 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    033 *          Lesser General Public License for more details. <br>
    034 * <br>
    035 *          You should have received a copy of the GNU Lesser General Public
    036 *          License along with this library; if not see
    037 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    038 */
    039public class InstructorConstraint extends GlobalConstraint<TeachingRequest.Variable, TeachingAssignment> {
    040
    041    /**
    042     * Constructor
    043     */
    044    public InstructorConstraint() {}
    045
    046    @Override
    047    public void computeConflicts(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, TeachingAssignment value, Set<TeachingAssignment> conflicts) {
    048        Context context = value.getInstructor().getContext(assignment);
    049
    050        // Check availability
    051        if (context.getInstructor().getTimePreference(value.variable().getRequest()).isProhibited()) {
    052            conflicts.add(value);
    053            return;
    054        }
    055
    056        // Check for overlaps
    057        for (TeachingAssignment ta : context.getAssignments()) {
    058            if (ta.variable().equals(value.variable()) || conflicts.contains(ta))
    059                continue;
    060
    061            if (ta.variable().getRequest().overlaps(value.variable().getRequest()))
    062                conflicts.add(ta);
    063        }
    064
    065        // Same course and/or common
    066        for (TeachingAssignment ta : context.getAssignments()) {
    067            if (ta.variable().equals(value.variable()) || conflicts.contains(ta))
    068                continue;
    069            if (ta.variable().getRequest().isSameCourseViolated(value.variable().getRequest()) || ta.variable().getRequest().isSameCommonViolated(value.variable().getRequest()))
    070                conflicts.add(ta);
    071        }
    072
    073        // Check load
    074        float load = value.variable().getRequest().getLoad();
    075        List<TeachingAssignment> adepts = new ArrayList<TeachingAssignment>();
    076        for (TeachingAssignment ta : context.getAssignments()) {
    077            if (ta.variable().equals(value.variable()) || conflicts.contains(ta))
    078                continue;
    079
    080            adepts.add(ta);
    081            load += ta.variable().getRequest().getLoad();
    082        }
    083        while (load > context.getInstructor().getMaxLoad()) {
    084            if (adepts.isEmpty()) {
    085                conflicts.add(value);
    086                break;
    087            }
    088            TeachingAssignment conflict = ToolBox.random(adepts);
    089            load -= conflict.variable().getRequest().getLoad();
    090            adepts.remove(conflict);
    091            conflicts.add(conflict);
    092        }
    093    }
    094
    095    @Override
    096    public String getName() {
    097        return "Instructor Constraint";
    098    }
    099
    100    @Override
    101    public String toString() {
    102        return getName();
    103    }
    104}