Course Timetabling Model

- added an ability to change whether student sectioning informations are saved/restored with best solution
  - methods isOnFlySectioningEnabled(), setOnFlySectioningEnabled(boolean)
- restore best: when on-fly sectioning is enabled, considerably speed up restore best solution
  (when there are a lot of jenrl constraints that can be removed as students have been moved avay of the appropriate class pairs)
- student conflict criteria (getStudentConflictCriteria()) moved from StudentSwapSectioning to TimetableModel

src/org/cpsolver/coursett/model/TimetableModel.java

@@ -4,6 +4,7 @@
 import java.util.BitSet;
 import java.util.Collection;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
@@ -105,6 +106,9 @@ public class TimetableModel extends ConstantModel<Lecture, Placement> {
 
     private StudentSectioning iStudentSectioning = null;
     private List<StudentGroup> iStudentGroups = new ArrayList<StudentGroup>();
+
+    private boolean iUseCriteria = true;
+    private List<StudentConflict> iStudentConflictCriteria = null;
 
     @SuppressWarnings("unchecked")
     public TimetableModel(DataProperties properties) {
@@ -188,7 +192,7 @@ else if (properties.getPropertyBoolean("General.AllowProhibitedRooms", false)) {
                 sLogger.error("Unable to use " + constraint + ": " + e.getMessage());
             }
         }
-
+        iUseCriteria = properties.getPropertyBoolean("SctSectioning.UseCriteria", true);
     }
 
     public DistanceMetric getDistanceMetric() {
@@ -663,6 +667,24 @@ public void restoreBest(Assignment<Lecture, Placement> assignment) {
                 }
             }
             // remove empty joint enrollments
+            for (Iterator<JenrlConstraint> i = iJenrlConstraints.iterator(); i.hasNext(); ) {
+                JenrlConstraint jenrl = i.next();
+                if (jenrl.getNrStudents() == 0) {
+                    jenrl.getContext(assignment).unassigned(assignment, null);
+                    Object[] vars = jenrl.variables().toArray();
+                    for (int k = 0; k < vars.length; k++)
+                        jenrl.removeVariable((Lecture) vars[k]);
+                    i.remove();
+                }
+            }
+            for (Iterator<Constraint<Lecture, Placement>> i = constraints().iterator(); i.hasNext(); ) {
+                Constraint<Lecture, Placement> c = i.next();
+                if (c instanceof JenrlConstraint && ((JenrlConstraint)c).getNrStudents() == 0) {
+                    removeReference((JenrlConstraint)c);
+                    i.remove();
+                }
+            }
+            /*
             for (JenrlConstraint jenrl: new ArrayList<JenrlConstraint>(getJenrlConstraints())) {
                 if (jenrl.getNrStudents() == 0) {
                     jenrl.getContext(assignment).unassigned(assignment, null);
@@ -672,9 +694,39 @@ public void restoreBest(Assignment<Lecture, Placement> assignment) {
                     removeConstraint(jenrl);
                 }
             }
+            */
         }
         super.restoreBest(assignment);
     }
 
     public boolean isAllowBreakHard() { return iAllowBreakHard; }
+
+    public boolean isOnFlySectioningEnabled() { return iOnFlySectioning; }
+    public void setOnFlySectioningEnabled(boolean onFlySectioning) { iOnFlySectioning = onFlySectioning; }
+
+    @Override
+    public void addCriterion(Criterion<Lecture, Placement> criterion) {
+        super.addCriterion(criterion);
+        iStudentConflictCriteria = null;
+    }
+
+    @Override
+    public void removeCriterion(Criterion<Lecture, Placement> criterion) {
+        super.removeCriterion(criterion);
+        iStudentConflictCriteria = null;
+    }
+
+    /**
+     * List of student conflict criteria
+     */
+    public List<StudentConflict> getStudentConflictCriteria() {
+        if (!iUseCriteria) return null;
+        if (iStudentConflictCriteria == null) {
+            iStudentConflictCriteria = new ArrayList<StudentConflict>();
+            for (Criterion<Lecture, Placement> criterion: getCriteria())
+                if (criterion instanceof StudentConflict)
+                    iStudentConflictCriteria.add((StudentConflict)criterion);
+        }
+        return iStudentConflictCriteria;
+    }
 }

src/org/cpsolver/coursett/sectioning/StudentSwapSectioning.java

@@ -1,6 +1,5 @@
 package org.cpsolver.coursett.sectioning;
 
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.HashMap;
@@ -22,7 +21,6 @@
 import org.cpsolver.coursett.model.TimetableModel;
 import org.cpsolver.coursett.sectioning.SctSectioning.GroupBasedInitialSectioning;
 import org.cpsolver.ifs.assignment.Assignment;
-import org.cpsolver.ifs.criteria.Criterion;
 import org.cpsolver.ifs.model.InfoProvider;
 import org.cpsolver.ifs.model.Neighbour;
 import org.cpsolver.ifs.solution.Solution;
@@ -54,28 +52,19 @@
  *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
  */
 public class StudentSwapSectioning extends DefaultStudentSectioning implements InfoProvider<Lecture, Placement> {
-    List<StudentConflict> iStudentConflictCriteria = null;
     private static double sEps = 0.0001;
     private double iGroupWeight = 0.1;
-    private boolean iUseCriteria = true;
     private int iMaxIdleResection = 1000;
 
     public StudentSwapSectioning(TimetableModel model) {
         super(model);
-        iUseCriteria = model.getProperties().getPropertyBoolean("StudentSwaps.UseCriteria", true);
         iGroupWeight = model.getProperties().getPropertyDouble("StudentSwaps.GroupWeight", 10.0);
         iMaxIdleResection = model.getProperties().getPropertyInt("StudentSwaps.MaxIdleResection", 1000);
     }
 
     protected List<StudentConflict> getStudentConflictCriteria() {
-        if (!iUseCriteria) return null;
-        if (iStudentConflictCriteria == null && iModel != null) {
-            iStudentConflictCriteria = new ArrayList<StudentConflict>();
-            for (Criterion<Lecture, Placement> criterion: iModel.getCriteria())
-                if (criterion instanceof StudentConflict)
-                    iStudentConflictCriteria.add((StudentConflict)criterion);
-        }
-        return iStudentConflictCriteria;
+        if (iModel != null) return iModel.getStudentConflictCriteria();
+        return null;
     }
 
     @Override