001 package net.sf.cpsolver.coursett.constraint;
002
003 import java.util.Collection;
004 import java.util.Comparator;
005 import java.util.List;
006 import java.util.Set;
007 import java.util.TreeSet;
008
009 import net.sf.cpsolver.coursett.model.Lecture;
010 import net.sf.cpsolver.coursett.model.Placement;
011 import 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 Tomas Muller<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
036 public 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 }