001package org.cpsolver.coursett.criteria.placement;
002
003import java.util.Collection;
004import java.util.Map;
005import java.util.Set;
006
007import org.cpsolver.coursett.model.Lecture;
008import org.cpsolver.coursett.model.Placement;
009import org.cpsolver.ifs.assignment.Assignment;
010import org.cpsolver.ifs.extension.ConflictStatistics;
011import org.cpsolver.ifs.extension.Extension;
012import org.cpsolver.ifs.solution.Solution;
013import org.cpsolver.ifs.solution.SolutionListener;
014import org.cpsolver.ifs.solver.Solver;
015
016
017/**
018 * Hard conflicts weighted by the conflict-based statistics (past occurrences).
019 * <br>
020 * 
021 * @version CourseTT 1.3 (University Course Timetabling)<br>
022 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
023 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
024 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
025 * <br>
026 *          This library is free software; you can redistribute it and/or modify
027 *          it under the terms of the GNU Lesser General Public License as
028 *          published by the Free Software Foundation; either version 3 of the
029 *          License, or (at your option) any later version. <br>
030 * <br>
031 *          This library is distributed in the hope that it will be useful, but
032 *          WITHOUT ANY WARRANTY; without even the implied warranty of
033 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
034 *          Lesser General Public License for more details. <br>
035 * <br>
036 *          You should have received a copy of the GNU Lesser General Public
037 *          License along with this library; if not see
038 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
039 */
040public class WeightedHardConflicts extends PlacementSelectionCriterion implements SolutionListener<Lecture, Placement> {
041    protected ConflictStatistics<Lecture, Placement> iStat = null;
042    
043    @Override
044    public boolean init(Solver<Lecture, Placement> solver) {
045        super.init(solver);
046        for (Extension<Lecture, Placement> extension : solver.getExtensions()) {
047            if (ConflictStatistics.class.isInstance(extension))
048                iStat = (ConflictStatistics<Lecture, Placement>) extension;
049        }
050        solver.currentSolution().addSolutionListener(this);
051        return true;
052    }
053    
054    @Override
055    public String getPlacementSelectionWeightName() {
056        return "Placement.NrConflictsWeight";
057    }
058
059    @Override
060    public double getValue(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
061        if (iStat != null && conflicts != null && !conflicts.isEmpty()) {
062            return iStat.countRemovals(((IterationContext)getContext(assignment)).getIteration(), conflicts, value);
063        } else {
064            return 0.0;
065        }
066    }
067
068    @Override
069    public double getPlacementSelectionWeightDefault(int level) {
070        return (level == 0 ? 3.0 : 0.0);
071    }
072
073    @Override
074    public void solutionUpdated(Solution<Lecture, Placement> solution) {
075        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
076    }
077
078    @Override
079    public void getInfo(Solution<Lecture, Placement> solution, Map<String, String> info) {
080    }
081
082    @Override
083    public void getInfo(Solution<Lecture, Placement> solution, Map<String, String> info, Collection<Lecture> variables) {
084    }
085
086    @Override
087    public void bestCleared(Solution<Lecture, Placement> solution) {
088        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
089    }
090
091    @Override
092    public void bestSaved(Solution<Lecture, Placement> solution) {
093        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
094    }
095
096    @Override
097    public void bestRestored(Solution<Lecture, Placement> solution) {
098        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
099    }
100    
101    @Override
102    public ValueContext createAssignmentContext(Assignment<Lecture, Placement> assignment) {
103        return new IterationContext(assignment);
104    }
105
106    public class IterationContext extends ValueContext {
107        protected long iIteration = 0;
108
109        protected IterationContext(Assignment<Lecture, Placement> assignment) {
110            super(assignment);
111        }
112        
113        public void setIteration(long iteration) {
114            iIteration = iteration;
115        }
116        
117        public long getIteration() {
118            return iIteration;
119        }
120    }
121}