001    package net.sf.cpsolver.studentsct.heuristics.selection;
002    
003    import org.apache.log4j.Logger;
004    
005    import net.sf.cpsolver.ifs.model.Neighbour;
006    import net.sf.cpsolver.ifs.solution.Solution;
007    import net.sf.cpsolver.ifs.solver.Solver;
008    import net.sf.cpsolver.ifs.util.DataProperties;
009    import net.sf.cpsolver.ifs.util.Progress;
010    import net.sf.cpsolver.studentsct.heuristics.studentord.StudentOrder;
011    import net.sf.cpsolver.studentsct.heuristics.studentord.StudentRandomOrder;
012    import net.sf.cpsolver.studentsct.model.Enrollment;
013    import net.sf.cpsolver.studentsct.model.Request;
014    import net.sf.cpsolver.studentsct.model.Student;
015    
016    /**
017     * Resection incomplete studends. An extension of {@link BranchBoundSelection},
018     * where only students that are not complete ({@link Student#isComplete()} is
019     * false) and that are sectioned somewhere ({@link Student#nrAssignedRequests()}
020     * is greater then zero) are resectioned.
021     * 
022     * <br>
023     * <br>
024     * 
025     * @version StudentSct 1.2 (Student Sectioning)<br>
026     *          Copyright (C) 2007 - 2010 Tomas Muller<br>
027     *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
028     *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
029     * <br>
030     *          This library is free software; you can redistribute it and/or modify
031     *          it under the terms of the GNU Lesser General Public License as
032     *          published by the Free Software Foundation; either version 3 of the
033     *          License, or (at your option) any later version. <br>
034     * <br>
035     *          This library is distributed in the hope that it will be useful, but
036     *          WITHOUT ANY WARRANTY; without even the implied warranty of
037     *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
038     *          Lesser General Public License for more details. <br>
039     * <br>
040     *          You should have received a copy of the GNU Lesser General Public
041     *          License along with this library; if not see
042     *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
043     */
044    
045    public class ResectionIncompleteStudentsSelection extends BranchBoundSelection {
046        private static Logger sLog = Logger.getLogger(ResectionIncompleteStudentsSelection.class);
047    
048        public ResectionIncompleteStudentsSelection(DataProperties properties) {
049            super(properties);
050            iOrder = new StudentRandomOrder(properties);
051            if (properties.getProperty("Neighbour.ResectionIncompleteStudentsOrder") != null) {
052                try {
053                    iOrder = (StudentOrder) Class.forName(
054                            properties.getProperty("Neighbour.ResectionIncompleteStudentsOrder")).getConstructor(
055                            new Class[] { DataProperties.class }).newInstance(new Object[] { properties });
056                } catch (Exception e) {
057                    sLog.error("Unable to set student order, reason:" + e.getMessage(), e);
058                }
059            }
060        }
061    
062        @Override
063        public void init(Solver<Request, Enrollment> solver) {
064            init(solver, "Resection incomplete students...");
065        }
066    
067        /**
068         * Select neighbour. All students with an incomplete and non-empty schedule
069         * are taken, one by one in a random order. For each student a branch &
070         * bound search is employed.
071         */
072        @Override
073        public Neighbour<Request, Enrollment> selectNeighbour(Solution<Request, Enrollment> solution) {
074            while (iStudentsEnumeration.hasNext()) {
075                Student student = iStudentsEnumeration.next();
076                Progress.getInstance(solution.getModel()).incProgress();
077                if (student.nrAssignedRequests() == 0 || student.isComplete())
078                    continue;
079                Neighbour<Request, Enrollment> neighbour = getSelection(student).select();
080                if (neighbour != null)
081                    return neighbour;
082            }
083            return null;
084        }
085    
086    }