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 * @author  Tomáš Müller
022 * @version CourseTT 1.3 (University Course Timetabling)<br>
023 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
024 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
025 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
026 * <br>
027 *          This library is free software; you can redistribute it and/or modify
028 *          it under the terms of the GNU Lesser General Public License as
029 *          published by the Free Software Foundation; either version 3 of the
030 *          License, or (at your option) any later version. <br>
031 * <br>
032 *          This library is distributed in the hope that it will be useful, but
033 *          WITHOUT ANY WARRANTY; without even the implied warranty of
034 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
035 *          Lesser General Public License for more details. <br>
036 * <br>
037 *          You should have received a copy of the GNU Lesser General Public
038 *          License along with this library; if not see
039 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
040 */
041public class WeightedHardConflicts extends PlacementSelectionCriterion implements SolutionListener<Lecture, Placement> {
042    protected ConflictStatistics<Lecture, Placement> iStat = null;
043    
044    @Override
045    public boolean init(Solver<Lecture, Placement> solver) {
046        super.init(solver);
047        for (Extension<Lecture, Placement> extension : solver.getExtensions()) {
048            if (ConflictStatistics.class.isInstance(extension))
049                iStat = (ConflictStatistics<Lecture, Placement>) extension;
050        }
051        solver.currentSolution().addSolutionListener(this);
052        return true;
053    }
054    
055    @Override
056    public String getPlacementSelectionWeightName() {
057        return "Placement.NrConflictsWeight";
058    }
059
060    @Override
061    public double getValue(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
062        if (iStat != null && conflicts != null && !conflicts.isEmpty()) {
063            return iStat.countRemovals(((IterationContext)getContext(assignment)).getIteration(), conflicts, value);
064        } else {
065            return 0.0;
066        }
067    }
068
069    @Override
070    public double getPlacementSelectionWeightDefault(int level) {
071        return (level == 0 ? 3.0 : 0.0);
072    }
073
074    @Override
075    public void solutionUpdated(Solution<Lecture, Placement> solution) {
076        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
077    }
078
079    @Override
080    public void getInfo(Solution<Lecture, Placement> solution, Map<String, String> info) {
081    }
082
083    @Override
084    public void getInfo(Solution<Lecture, Placement> solution, Map<String, String> info, Collection<Lecture> variables) {
085    }
086
087    @Override
088    public void bestCleared(Solution<Lecture, Placement> solution) {
089        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
090    }
091
092    @Override
093    public void bestSaved(Solution<Lecture, Placement> solution) {
094        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
095    }
096
097    @Override
098    public void bestRestored(Solution<Lecture, Placement> solution) {
099        ((IterationContext)getContext(solution.getAssignment())).setIteration(solution.getIteration());
100    }
101    
102    @Override
103    public ValueContext createAssignmentContext(Assignment<Lecture, Placement> assignment) {
104        return new IterationContext(assignment);
105    }
106
107    public class IterationContext extends ValueContext {
108        protected long iIteration = 0;
109
110        protected IterationContext(Assignment<Lecture, Placement> assignment) {
111            super(assignment);
112        }
113        
114        public void setIteration(long iteration) {
115            iIteration = iteration;
116        }
117        
118        public long getIteration() {
119            return iIteration;
120        }
121    }
122}