    001package org.cpsolver.exam.model;
    002
    003import java.util.ArrayList;
    004import java.util.HashSet;
    005import java.util.List;
    006import java.util.Set;
    007
    008import org.cpsolver.ifs.assignment.Assignment;
    009import org.cpsolver.ifs.model.Constraint;
    010
    011
    012/**
    013 * A student. <br>
    014 * <br>
    015 *
    016 * @author  Tomáš Müller
    017 * @version ExamTT 1.3 (Examination Timetabling)<br>
    018 *          Copyright (C) 2008 - 2014 Tomáš Müller<br>
    019 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    020 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    021 * <br>
    022 *          This library is free software; you can redistribute it and/or modify
    023 *          it under the terms of the GNU Lesser General Public License as
    024 *          published by the Free Software Foundation; either version 3 of the
    025 *          License, or (at your option) any later version. <br>
    026 * <br>
    027 *          This library is distributed in the hope that it will be useful, but
    028 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    029 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    030 *          Lesser General Public License for more details. <br>
    031 * <br>
    032 *          You should have received a copy of the GNU Lesser General Public
    033 *          License along with this library; if not see
    034 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    035 */
    036public class ExamStudent extends Constraint<Exam, ExamPlacement> {
    037    private boolean iAllowDirectConflicts = true;
    038    private List<ExamOwner> iOwners = new ArrayList<ExamOwner>();
    039    private boolean[] iAvailable = null;
    040
    041    /**
    042     * Constructor
    043     *
    044     * @param model
    045     *            examination timetabling model
    046     * @param id
    047     *            student unique id
    048     */
    049    public ExamStudent(ExamModel model, long id) {
    050        super();
    051        iAllowDirectConflicts = model.getProperties().getPropertyBoolean("Student.AllowDirectConflicts", iAllowDirectConflicts);
    052        iId = id;
    053        setModel(model);
    054    }
    055
    056    /**
    057     * True if direct student conflicts are allowed for this student
    058     * @return direct conflicts are allowed
    059     */
    060    public boolean isAllowDirectConflicts() {
    061        return iAllowDirectConflicts;
    062    }
    063
    064    /**
    065     * Set whether direct student conflicts are allowed for this student
    066     * @param allowDirectConflicts direct conflicts are allowed
    067     */
    068    public void setAllowDirectConflicts(boolean allowDirectConflicts) {
    069        iAllowDirectConflicts = allowDirectConflicts;
    070    }
    071
    072    /**
    073     * True if the given two exams can have a direct student conflict with this
    074     * student, i.e., they can be placed at the same period.
    075     *
    076     * @param ex1
    077     *            an exam
    078     * @param ex2
    079     *            an exam
    080     * @return {@link ExamStudent#isAllowDirectConflicts()} and
    081     *         {@link Exam#isAllowDirectConflicts()} for both exams
    082     */
    083    public boolean canConflict(Exam ex1, Exam ex2) {
    084        return isAllowDirectConflicts() && ex1.isAllowDirectConflicts() && ex2.isAllowDirectConflicts();
    085    }
    086
    087    /**
    088     * Exam(s) enrolled by the student that are scheduled in the given period
    089     * @param assignment current assignment
    090     * @param period given period
    091     * @return set of exams that this student is enrolled into and that are placed in the given period
    092     */
    093    public Set<Exam> getExams(Assignment<Exam, ExamPlacement> assignment, ExamPeriod period) {
    094        Set<Exam> exams = ((ExamModel)getModel()).getStudentsOfPeriod(assignment, period).get(this);
    095        return (exams != null ? exams : new HashSet<Exam>());
    096        // return getContext(assignment).getExams(period.getIndex());
    097    }
    098
    099    /**
    100     * Exam(s) enrolled by the student that are scheduled in the given day
    101     * @param assignment current assignment
    102     * @param period given period
    103     * @return set of exams that this student is enrolled into and that are placed in the day of the given period
    104     */
    105    public Set<Exam> getExamsADay(Assignment<Exam, ExamPlacement> assignment, ExamPeriod period) {
    106        Set<Exam> exams = ((ExamModel)getModel()).getStudentsOfDay(assignment, period).get(this);
    107        return (exams != null ? exams : new HashSet<Exam>());
    108        // return getContext(assignment).getExamsOfDay(period.getDay());
    109    }
    110
    111    /**
    112     * Exam(s) enrolled by the student that are scheduled in the given day
    113     * @param assignment current assignment
    114     * @param day given day
    115     * @return set of exams that this student is enrolled into and that are placed in the given day
    116     */
    117    public Set<Exam> getExamsADay(Assignment<Exam, ExamPlacement> assignment, int day) {
    118        Set<Exam> exams = ((ExamModel)getModel()).getStudentsOfDay(assignment, day).get(this);
    119        return (exams != null ? exams : new HashSet<Exam>());
    120        // return getContext(assignment).getExamsOfDay(day);
    121    }
    122
    123    /**
    124     * Compute conflicts between the given assignment of an exam and all the
    125     * current assignments (of this student). Only not-allowed conflicts (see
    126     * {@link ExamStudent#canConflict(Exam, Exam)} are considered.
    127     */
    128    @Override
    129    public void computeConflicts(Assignment<Exam, ExamPlacement> assignment, ExamPlacement p, Set<ExamPlacement> conflicts) {
    130        Exam ex = p.variable();
    131        Set<Exam> exams = ((ExamModel)getModel()).getStudentsOfPeriod(assignment, p.getPeriod()).get(this);
    132        if (exams != null)
    133            for (Exam exam : exams) {
    134                if (!canConflict(ex, exam))
    135                    conflicts.add(assignment.getValue(exam));
    136            }
    137    }
    138
    139    /**
    140     * Check whether there is a conflict between the given assignment of an exam
    141     * and all the current assignments (of this student). Only not-allowed
    142     * conflicts (see {@link ExamStudent#canConflict(Exam, Exam)} are
    143     * considered.
    144     */
    145    @Override
    146    public boolean inConflict(Assignment<Exam, ExamPlacement> assignment, ExamPlacement p) {
    147        Exam ex = p.variable();
    148        Set<Exam> exams = ((ExamModel)getModel()).getStudentsOfPeriod(assignment, p.getPeriod()).get(this);
    149        if (exams != null)
    150            for (Exam exam : exams) {
    151                if (!canConflict(ex, exam))
    152                    return true;
    153            }
    154        return false;
    155    }
    156
    157    /**
    158     * True if the given exams can conflict (see
    159     * {@link ExamStudent#canConflict(Exam, Exam)}), or if they are placed at
    160     * different periods.
    161     */
    162    @Override
    163    public boolean isConsistent(ExamPlacement p1, ExamPlacement p2) {
    164        return (p1.getPeriod() != p2.getPeriod() || canConflict(p1.variable(), p2.variable()));
    165    }
    166
    167    /**
    168     * Compare two student for equality
    169     */
    170    @Override
    171    public boolean equals(Object o) {
    172        if (o == null || !(o instanceof ExamStudent))
    173            return false;
    174        ExamStudent s = (ExamStudent) o;
    175        return getId() == s.getId();
    176    }
    177
    178    /**
    179     * Hash code
    180     */
    181    @Override
    182    public int hashCode() {
    183        return (int) (getId() ^ (getId() >>> 32));
    184    }
    185
    186    /**
    187     * Student unique id
    188     */
    189    @Override
    190    public String toString() {
    191        return String.valueOf(getId());
    192    }
    193
    194    /**
    195     * Compare two students (by student ids)
    196     */
    197    @Override
    198    public int compareTo(Constraint<Exam, ExamPlacement> o) {
    199        return toString().compareTo(o.toString());
    200    }
    201
    202    /**
    203     * Constraint is hard if {@link ExamStudent#isAllowDirectConflicts()} is
    204     * false.
    205     */
    206    @Override
    207    public boolean isHard() {
    208        return !isAllowDirectConflicts();
    209    }
    210
    211    /**
    212     * Courses and/or sections that this student is enrolled to
    213     *
    214     * @return list of {@link ExamOwner}
    215     */
    216    public List<ExamOwner> getOwners() {
    217        return iOwners;
    218    }
    219
    220    /**
    221     * True if the student is available (for examination timetabling) during the
    222     * given period
    223     *
    224     * @param period
    225     *            a period
    226     * @return true if a student can attend an exam at the given period, false
    227     *         if otherwise
    228     */
    229    public boolean isAvailable(ExamPeriod period) {
    230        return (iAvailable == null ? true : iAvailable[period.getIndex()]);
    231    }
    232
    233    /**
    234     * Set whether the student is available (for examination timetabling) during
    235     * the given period
    236     *
    237     * @param period
    238     *            a period
    239     * @param available
    240     *            true if a student can attend an exam at the given period,
    241     *            false if otherwise
    242     */
    243    public void setAvailable(int period, boolean available) {
    244        if (iAvailable == null) {
    245            iAvailable = new boolean[((ExamModel)getModel()).getNrPeriods()];
    246            for (int i = 0; i < iAvailable.length; i++)
    247                iAvailable[i] = true;
    248        }
    249        iAvailable[period] = available;
    250    }
    251
    252    /*
    253    @Override
    254    public Context createAssignmentContext(Assignment<Exam, ExamPlacement> assignment) {
    255        return new Context(assignment);
    256    }
    257
    258    public class Context implements AssignmentConstraintContext<Exam, ExamPlacement> {
    259        private Set<Exam>[] iTable;
    260        private Set<Exam>[] iDayTable;
    261
    262        @SuppressWarnings("unchecked")
    263        public Context(Assignment<Exam, ExamPlacement> assignment) {
    264            ExamModel model = (ExamModel)getModel();
    265            iTable = new Set[model.getNrPeriods()];
    266            for (int i = 0; i < iTable.length; i++)
    267                iTable[i] = new HashSet<Exam>();
    268            iDayTable = new Set[model.getNrDays()];
    269            for (int i = 0; i < iDayTable.length; i++)
    270                iDayTable[i] = new HashSet<Exam>();
    271            for (Exam exam: variables()) {
    272                ExamPlacement placement = assignment.getValue(exam);
    273                if (placement != null)
    274                    assigned(assignment, placement);
    275            }
    276        }
    277
    278        @Override
    279        public void assigned(Assignment<Exam, ExamPlacement> assignment, ExamPlacement placement) {
    280            iTable[placement.getPeriod().getIndex()].add(placement.variable());
    281            iDayTable[placement.getPeriod().getDay()].add(placement.variable());
    282        }
    283
    284        @Override
    285        public void unassigned(Assignment<Exam, ExamPlacement> assignment, ExamPlacement placement) {
    286            iTable[placement.getPeriod().getIndex()].remove(placement.variable());
    287            iDayTable[placement.getPeriod().getDay()].remove(placement.variable());
    288        }
    289
    290
    291        public Set<Exam> getExams(int period) { return iTable[period]; }
    292
    293        public Set<Exam> getExamsOfDay(int day) { return iDayTable[day]; }
    294
    295    }
    296    */
    297}