    001package org.cpsolver.exam.model;
    002
    003import java.util.ArrayList;
    004import java.util.Collection;
    005import java.util.List;
    006import java.util.Set;
    007
    008import org.cpsolver.coursett.IdConvertor;
    009import org.cpsolver.ifs.model.Model;
    010import org.cpsolver.ifs.util.DataProperties;
    011import org.cpsolver.ifs.util.ToolBox;
    012import org.dom4j.Element;
    013
    014
    015/**
    016 * Abstract room sharing model. Defines when and under what conditions two or more exams can share a room.<br>
    017 * <br>
    018 *
    019 * @version ExamTT 1.3 (Examination Timetabling)<br>
    020 *          Copyright (C) 2008 - 2014 Tomáš Müller<br>
    021 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    022 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    023 * <br>
    024 *          This library is free software; you can redistribute it and/or modify
    025 *          it under the terms of the GNU Lesser General Public License as
    026 *          published by the Free Software Foundation; either version 3 of the
    027 *          License, or (at your option) any later version. <br>
    028 * <br>
    029 *          This library is distributed in the hope that it will be useful, but
    030 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    031 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    032 *          Lesser General Public License for more details. <br>
    033 * <br>
    034 *          You should have received a copy of the GNU Lesser General Public
    035 *          License along with this library; if not see
    036 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    037 */
    038public abstract class ExamRoomSharing  {
    039
    040    public ExamRoomSharing(Model<Exam, ExamPlacement> model, DataProperties config) {}
    041
    042    /**
    043     * True if given examination can not be placed in the same room at the same period as the other examinations
    044     * @param exam examination placement in question
    045     * @param other exams currently assigned in the room at the requested period
    046     * @param room examination room in questions
    047     * @return true if there is a conflict
    048     */
    049    public boolean inConflict(ExamPlacement exam, Collection<ExamPlacement> other, ExamRoom room) {
    050        if (exam.getRoomPlacements().size() != 1)
    051            return !other.isEmpty();
    052
    053        return inConflict(exam.variable(), other, room);
    054    }
    055
    056    /**
    057     * True if given examination can not be placed in the same room at the same period as the other examinations
    058     * @param exam examination in question
    059     * @param other exams currently assigned in the room at the requested period
    060     * @param room examination room in questions
    061     * @return true if there is a conflict
    062     */
    063    public boolean inConflict(Exam exam, Collection<ExamPlacement> other, ExamRoom room) {
    064        int total = exam.getSize();
    065        boolean altSeating = exam.hasAltSeating();
    066        for (ExamPlacement x: other) {
    067            if (x.variable().equals(exam)) continue;
    068            if (x.getRoomPlacements().size() != 1) return true; // already split into multiple rooms
    069            if (!canShareRoom(exam, x.variable())) return true; // sharing not allowed between the pair
    070            total += x.variable().getSize();
    071            if (x.variable().hasAltSeating()) altSeating = true;
    072        }
    073
    074        return total > (altSeating ? room.getAltSize() : room.getSize()); // check size limit
    075    }
    076
    077    /**
    078     * Compute conflicting placement for the case when a given examination needs to be placed in the same room at the same period as the other examinations
    079     * @param exam examination placement in question
    080     * @param other exams currently assigned in the room at the requested period
    081     * @param room examination room in questions
    082     * @param conflicts set of conflicting assignments
    083     */
    084    public void computeConflicts(ExamPlacement exam, Collection<ExamPlacement> other, ExamRoom room, Set<ExamPlacement> conflicts) {
    085        // more than one room is required -> no sharing
    086        if (exam.getRoomPlacements().size() != 1) {
    087            conflicts.addAll(other);
    088            return;
    089        }
    090
    091        computeConflicts(exam.variable(), other, room, conflicts);
    092    }
    093
    094    /**
    095     * Compute conflicting placement for the case when a given examination needs to be placed in the same room at the same period as the other examinations
    096     * @param exam examination in question
    097     * @param other exams currently assigned in the room at the requested period
    098     * @param room examination room in questions
    099     * @param conflicts set of conflicting assignments
    100     */
    101    public void computeConflicts(Exam exam, Collection<ExamPlacement> other, ExamRoom room, Set<ExamPlacement> conflicts) {
    102        int total = exam.getSize();
    103        boolean altSeating = exam.hasAltSeating();
    104        List<ExamPlacement> adepts = new ArrayList<ExamPlacement>();
    105        for (ExamPlacement x: other) {
    106            if (x.variable().equals(exam)) continue;
    107            // already split into multiple rooms
    108            if (x.getRoomPlacements().size() != 1) {
    109                conflicts.add(x); continue;
    110            }
    111            // sharing not allowed between the pair
    112            if (!canShareRoom(exam, x.variable())) {
    113                conflicts.add(x); continue;
    114            }
    115            if (x.variable().hasAltSeating()) altSeating = true;
    116            total += x.variable().getSize();
    117            adepts.add(x);
    118        }
    119
    120        // fix the total size if needed
    121        while (total > (altSeating ? room.getAltSize() : room.getSize()) && !adepts.isEmpty()) {
    122            ExamPlacement x = ToolBox.random(adepts);
    123            adepts.remove(x);
    124            conflicts.add(x);
    125            total -= x.variable().getSize();
    126        }
    127    }
    128
    129
    130    /**
    131     * True if given two exams can share a room
    132     * @param x1 first exam
    133     * @param x2 second exam
    134     * @return true if the two exams can share a room
    135     */
    136    public abstract boolean canShareRoom(Exam x1, Exam x2);
    137
    138    /**
    139     * Save sharing information (if needed) for a given exam
    140     * @param exam exam in question
    141     * @param element XML exam element to include sharing information
    142     * @param idConvertor id converter
    143     */
    144    public void save(Exam exam, Element element, IdConvertor idConvertor) {}
    145
    146    /**
    147     * Load sharing information (if needed) for a given exam
    148     * @param exam exam in question
    149     * @param element XML exam element including sharing information
    150     */
    151    public void load(Exam exam, Element element) {}
    152}