001    package net.sf.cpsolver.studentsct.model;
002    
003    import java.util.List;
004    
005    import net.sf.cpsolver.ifs.model.Variable;
006    
007    /**
008     * Representation of a request of a student for a course(s) or a free time. This
009     * can be either {@link CourseRequest} or {@link FreeTimeRequest}. Each request
010     * contains id, priority, weight, and a student. A request can be also marked as
011     * alternative. <br>
012     * <br>
013     * For each student, all non-alternative requests should be satisfied (an
014     * enrollment is assigned to a request). If not, an alternative request can be
015     * assigned instead of a non-alternative course request. In the case when only
016     * one of two requests can be assigned, the one with the lowest priority is
017     * preferred. <br>
018     * <br>
019     * 
020     * @version StudentSct 1.2 (Student Sectioning)<br>
021     *          Copyright (C) 2007 - 2010 Tomas Muller<br>
022     *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
023     *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
024     * <br>
025     *          This library is free software; you can redistribute it and/or modify
026     *          it under the terms of the GNU Lesser General Public License as
027     *          published by the Free Software Foundation; either version 3 of the
028     *          License, or (at your option) any later version. <br>
029     * <br>
030     *          This library is distributed in the hope that it will be useful, but
031     *          WITHOUT ANY WARRANTY; without even the implied warranty of
032     *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
033     *          Lesser General Public License for more details. <br>
034     * <br>
035     *          You should have received a copy of the GNU Lesser General Public
036     *          License along with this library; if not see
037     *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
038     */
039    public abstract class Request extends Variable<Request, Enrollment> {
040        private long iId = -1;
041        private int iPriority = 0;
042        private boolean iAlternative = false;
043        private Student iStudent = null;
044        private double iWeight = 1.0;
045        /** True means that method {@link Request#values()} will cache its results. */
046        public static boolean sCacheValues = false;
047    
048        /**
049         * Constructor
050         * 
051         * @param id
052         *            course/free time request unique id
053         * @param priority
054         *            request priority -- if there is a choice, request with lower
055         *            priority is more preferred to be assigned
056         * @param alternative
057         *            true if the request is alternative (alternative request can be
058         *            assigned instead of a non-alternative course requests, if it
059         *            is left unassigned)
060         * @param student
061         *            student to which this request belongs
062         */
063        public Request(long id, int priority, boolean alternative, Student student) {
064            iId = id;
065            iPriority = priority;
066            iAlternative = alternative;
067            iStudent = student;
068            iStudent.getRequests().add(this);
069        }
070    
071        /** Request id */
072        @Override
073        public long getId() {
074            return iId;
075        }
076    
077        /**
078         * Request priority -- if there is a choice, request with lower priority is
079         * more preferred to be assigned
080         */
081        public int getPriority() {
082            return iPriority;
083        }
084    
085        /** Set request priority */
086        public void setPriority(int priority) {
087            iPriority = priority;
088        }
089    
090        /**
091         * True, if the request is alternative (alternative request can be assigned
092         * instead of a non-alternative course requests, if it is left unassigned)
093         */
094        public boolean isAlternative() {
095            return iAlternative;
096        }
097    
098        /** Student to which this request belongs */
099        public Student getStudent() {
100            return iStudent;
101        }
102    
103        /**
104         * Compare to requests, non-alternative requests go first, otherwise use
105         * priority (a request with lower priority goes first)
106         */
107        @Override
108        public int compareTo(Request r) {
109            if (getStudent().getId() == r.getStudent().getId())
110                return (isAlternative() != r.isAlternative() ? isAlternative() ? 1 : -1 : getPriority() < r.getPriority() ? -1 : 1);
111            else
112                return getStudent().compareTo(r.getStudent());
113        }
114    
115        /** Compute available enrollments */
116        public abstract List<Enrollment> computeEnrollments();
117    
118        /**
119         * Domain of this variable -- list of available enrollments. Method
120         * {@link Request#computeEnrollments()} is used.
121         */
122        @Override
123        public List<Enrollment> values() {
124            List<Enrollment> values = super.values();
125            if (values != null)
126                return values;
127            values = computeEnrollments();
128            if (sCacheValues)
129                setValues(values);
130            return values;
131        }
132    
133        /**
134         * Assign given enrollment to this request. This method also calls
135         * {@link Assignment#assigned(Enrollment)} on for all the assignments of the
136         * enrollment.
137         */
138        @Override
139        public void assign(long iteration, Enrollment enrollment) {
140            super.assign(iteration, enrollment);
141            for (Assignment a : enrollment.getAssignments()) {
142                a.assigned(enrollment);
143            }
144            if (enrollment.getConfig() != null)
145                enrollment.getConfig().assigned(enrollment);
146            if (enrollment.getCourse() != null)
147                enrollment.getCourse().assigned(enrollment);
148            if (enrollment.getReservation() != null)
149                enrollment.getReservation().assigned(enrollment);
150        }
151    
152        /**
153         * Unassign currently assigned enrollment from this request. This method
154         * also calls {@link Assignment#unassigned(Enrollment)} on for all the
155         * assignments of the current enrollment.
156         */
157        @Override
158        public void unassign(long iteration) {
159            if (getAssignment() != null) {
160                Enrollment enrollment = getAssignment();
161                for (Assignment a : enrollment.getAssignments()) {
162                    a.unassigned(enrollment);
163                }
164                if (enrollment.getConfig() != null)
165                    enrollment.getConfig().unassigned(enrollment);
166                if (enrollment.getCourse() != null)
167                    enrollment.getCourse().unassigned(enrollment);
168                if (enrollment.getReservation() != null)
169                    enrollment.getReservation().unassigned(enrollment);
170            }
171            super.unassign(iteration);
172        }
173    
174        /** Get bound, i.e., the value of the best possible enrollment */
175        public abstract double getBound();
176    
177        /**
178         * Request weight, set by default to 1.0, defines the amount of space which
179         * will be taken in the section by this request.
180         */
181        public double getWeight() {
182            return iWeight;
183        }
184    
185        /**
186         * Set request weight. It defines the amount of space which will be taken in
187         * the section by this request.
188         */
189        public void setWeight(double weight) {
190            iWeight = weight;
191        }
192    
193        /** Return true if request is assigned. */
194        public boolean isAssigned() {
195            return getAssignment() != null;
196        }
197        
198        @Override
199        public int hashCode() {
200            return (int) (iId ^ (iId >>> 32) ^ getStudent().getId() ^ (getStudent().getId() >>> 32));
201        }
202        
203        @Override
204        public boolean equals(Object o) {
205            if (o == null || !(o instanceof Request)) return false;
206            return getId() == ((Request)o).getId() && getStudent().getId() == ((Request)o).getStudent().getId();
207        }
208    
209    }