    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 * @version IFS 1.3 (Instructor Sectioning)<br>
    020 *          Copyright (C) 2016 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 InstructorConstraint extends GlobalConstraint<TeachingRequest.Variable, TeachingAssignment> {
    039
    040    /**
    041     * Constructor
    042     */
    043    public InstructorConstraint() {}
    044
    045    @Override
    046    public void computeConflicts(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, TeachingAssignment value, Set<TeachingAssignment> conflicts) {
    047        Context context = value.getInstructor().getContext(assignment);
    048
    049        // Check availability
    050        if (context.getInstructor().getTimePreference(value.variable().getRequest()).isProhibited()) {
    051            conflicts.add(value);
    052            return;
    053        }
    054
    055        // Check for overlaps
    056        for (TeachingAssignment ta : context.getAssignments()) {
    057            if (ta.variable().equals(value.variable()) || conflicts.contains(ta))
    058                continue;
    059
    060            if (ta.variable().getRequest().overlaps(value.variable().getRequest()))
    061                conflicts.add(ta);
    062        }
    063
    064        // Same course and/or common
    065        for (TeachingAssignment ta : context.getAssignments()) {
    066            if (ta.variable().equals(value.variable()) || conflicts.contains(ta))
    067                continue;
    068            if (ta.variable().getRequest().isSameCourseViolated(value.variable().getRequest()) || ta.variable().getRequest().isSameCommonViolated(value.variable().getRequest()))
    069                conflicts.add(ta);
    070        }
    071
    072        // Check load
    073        float load = value.variable().getRequest().getLoad();
    074        List<TeachingAssignment> adepts = new ArrayList<TeachingAssignment>();
    075        for (TeachingAssignment ta : context.getAssignments()) {
    076            if (ta.variable().equals(value.variable()) || conflicts.contains(ta))
    077                continue;
    078
    079            adepts.add(ta);
    080            load += ta.variable().getRequest().getLoad();
    081        }
    082        while (load > context.getInstructor().getMaxLoad()) {
    083            if (adepts.isEmpty()) {
    084                conflicts.add(value);
    085                break;
    086            }
    087            TeachingAssignment conflict = ToolBox.random(adepts);
    088            load -= conflict.variable().getRequest().getLoad();
    089            adepts.remove(conflict);
    090            conflicts.add(conflict);
    091        }
    092    }
    093
    094    @Override
    095    public String getName() {
    096        return "Instructor Constraint";
    097    }
    098
    099    @Override
    100    public String toString() {
    101        return getName();
    102    }
    103}