    001package net.sf.cpsolver.coursett.constraint;
    002
    003import java.util.Collection;
    004import java.util.Comparator;
    005import java.util.List;
    006import java.util.Set;
    007import java.util.TreeSet;
    008
    009import net.sf.cpsolver.coursett.model.Lecture;
    010import net.sf.cpsolver.coursett.model.Placement;
    011import net.sf.cpsolver.ifs.model.Constraint;
    012
    013/**
    014 * Class limit constraint.
    015 *
    016 * @version CourseTT 1.2 (University Course Timetabling)<br>
    017 *          Copyright (C) 2006 - 2010 Tomáš Müller<br>
    018 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    019 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    020 * <br>
    021 *          This library is free software; you can redistribute it and/or modify
    022 *          it under the terms of the GNU Lesser General Public License as
    023 *          published by the Free Software Foundation; either version 3 of the
    024 *          License, or (at your option) any later version. <br>
    025 * <br>
    026 *          This library is distributed in the hope that it will be useful, but
    027 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    028 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    029 *          Lesser General Public License for more details. <br>
    030 * <br>
    031 *          You should have received a copy of the GNU Lesser General Public
    032 *          License along with this library; if not see
    033 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    034 */
    035
    036public class ClassLimitConstraint extends Constraint<Lecture, Placement> {
    037    private int iClassLimit = 0;
    038    private Lecture iParent = null;
    039    private String iName = null;
    040    boolean iEnabled = true;
    041
    042    private int iClassLimitDelta = 0;
    043
    044    public ClassLimitConstraint(int classLimit, String name) {
    045        iClassLimit = classLimit;
    046        iName = name;
    047    }
    048
    049    public ClassLimitConstraint(Lecture parent, String name) {
    050        iParent = parent;
    051        iName = name;
    052    }
    053
    054    public int getClassLimitDelta() {
    055        return iClassLimitDelta;
    056    }
    057
    058    public void setClassLimitDelta(int classLimitDelta) {
    059        iClassLimitDelta = classLimitDelta;
    060    }
    061
    062    public int classLimit() {
    063        return (iParent == null ? iClassLimit + iClassLimitDelta : iParent.minClassLimit() + iClassLimitDelta);
    064    }
    065
    066    public Lecture getParentLecture() {
    067        return iParent;
    068    }
    069
    070    public int currentClassLimit(Placement value, Set<Placement> conflicts) {
    071        int limit = 0;
    072        for (Lecture lecture : variables()) {
    073            limit += lecture.classLimit(value, conflicts);
    074        }
    075        return limit;
    076    }
    077
    078    @Override
    079    public void computeConflicts(Placement value, Set<Placement> conflicts) {
    080        if (!iEnabled)
    081            return;
    082        int currentLimit = currentClassLimit(value, conflicts);
    083        int classLimit = classLimit();
    084        if (currentLimit < classLimit) {
    085            // System.out.println(getName()+"> "+currentLimit+"<"+classLimit+" ("+value+")");
    086            TreeSet<Placement> adepts = new TreeSet<Placement>(new ClassLimitComparator());
    087            computeAdepts(adepts, variables(), value, conflicts);
    088            addParentAdepts(adepts, iParent, value, conflicts);
    089            // System.out.println(" -- found "+adepts.size()+" adepts");
    090            for (Placement adept : adepts) {
    091                // System.out.println("   -- selected "+adept);
    092                conflicts.add(adept);
    093                currentLimit = currentClassLimit(value, conflicts);
    094                // System.out.println("   -- new current limit "+currentLimit);
    095                if (currentLimit >= classLimit)
    096                    break;
    097            }
    098            // System.out.println(" -- done (currentLimit="+currentLimit+", classLimit="+classLimit+")");
    099        }
    100
    101        if (currentLimit < classLimit)
    102            conflicts.add(value);
    103
    104        if (iParent != null && iParent.getClassLimitConstraint() != null)
    105            iParent.getClassLimitConstraint().computeConflicts(value, conflicts);
    106    }
    107
    108    public void computeAdepts(Collection<Placement> adepts, List<Lecture> variables, Placement value,
    109            Set<Placement> conflicts) {
    110        for (Lecture lecture : variables) {
    111            if (lecture.isCommitted()) continue;
    112            Placement placement = lecture.getAssignment();
    113            if (placement != null && !placement.equals(value) && !conflicts.contains(placement)) {
    114                adepts.add(placement);
    115            }
    116            if (lecture.hasAnyChildren()) {
    117                for (Long subpartId: lecture.getChildrenSubpartIds()) {
    118                    computeAdepts(adepts, lecture.getChildren(subpartId), value, conflicts);
    119                }
    120            }
    121
    122        }
    123    }
    124
    125    public void addParentAdepts(Collection<Placement> adepts, Lecture parent, Placement value, Set<Placement> conflicts) {
    126        if (parent == null || parent.isCommitted() || parent.minClassLimit() == parent.maxClassLimit())
    127            return;
    128        Placement placement = parent.getAssignment();
    129        if (placement != null && !placement.equals(value) && !conflicts.contains(placement)) {
    130            adepts.add(placement);
    131        }
    132        addParentAdepts(adepts, parent.getParent(), value, conflicts);
    133    }
    134
    135    @Override
    136    public boolean inConflict(Placement value) {
    137        if (!iEnabled)
    138            return false;
    139        int currentLimit = currentClassLimit(value, null);
    140        int classLimit = classLimit();
    141        if (currentLimit < classLimit)
    142            return true;
    143
    144        if (iParent != null && iParent.getClassLimitConstraint() != null)
    145            return iParent.getClassLimitConstraint().inConflict(value);
    146
    147        return false;
    148    }
    149
    150    @Override
    151    public String getName() {
    152        return iName;
    153    }
    154
    155    private static class ClassLimitComparator implements Comparator<Placement> {
    156        @Override
    157        public int compare(Placement p1, Placement p2) {
    158            Lecture l1 = p1.variable();
    159            Lecture l2 = p2.variable();
    160            int cl1 = Math.min(l1.maxClassLimit(), (int) Math.floor(p1.getRoomSize() / l1.roomToLimitRatio()));
    161            int cl2 = Math.min(l2.maxClassLimit(), (int) Math.floor(p2.getRoomSize() / l2.roomToLimitRatio()));
    162            int cmp = -Double.compare(l1.maxAchievableClassLimit() - cl1, l2.maxAchievableClassLimit() - cl2);
    163            if (cmp != 0)
    164                return cmp;
    165            return l1.getClassId().compareTo(l2.getClassId());
    166        }
    167    }
    168
    169    public void setEnabled(boolean enabled) {
    170        iEnabled = enabled;
    171    }
    172
    173    public boolean isEnabled() {
    174        return iEnabled;
    175    }
    176
    177    @Override
    178    public String toString() {
    179        return "Class-limit " + getName();
    180    }
    181
    182}