001package org.cpsolver.studentsct.constraint; 002 003import java.util.Set; 004 005import org.cpsolver.ifs.assignment.Assignment; 006import org.cpsolver.ifs.model.Constraint; 007import org.cpsolver.studentsct.model.Enrollment; 008import org.cpsolver.studentsct.model.Request; 009import org.cpsolver.studentsct.model.Student; 010 011 012/** 013 * This constraints ensures that a student is not enrolled into sections that 014 * are overlapping in time. 015 * 016 * <br> 017 * <br> 018 * 019 * @version StudentSct 1.3 (Student Sectioning)<br> 020 * Copyright (C) 2007 - 2014 Tomas Muller<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 class StudentConflict extends Constraint<Request, Enrollment> { 039 040 /** 041 * Constructor 042 * @param student student for which the constraint is created 043 */ 044 public StudentConflict(Student student) { 045 super(); 046 for (Request request : student.getRequests()) 047 addVariable(request); 048 } 049 050 /** 051 * A given enrollment is conflicting when the student is enrolled into 052 * another course / free time request that has an assignment that is 053 * overlapping with one or more assignments of the given section. See 054 * {@link Enrollment#isOverlapping(Enrollment)} for more details. All such 055 * overlapping enrollments are added into the provided set of conflicts. 056 * 057 * @param enrollment 058 * {@link Enrollment} that is being considered 059 * @param conflicts 060 * resultant list of conflicting enrollments 061 */ 062 @Override 063 public void computeConflicts(Assignment<Request, Enrollment> assignment, Enrollment enrollment, Set<Enrollment> conflicts) { 064 // for all assigned course requests -> if overlapping with this 065 // enrollment -> conflict 066 for (Request request : variables()) { 067 if (request.equals(enrollment.getRequest())) 068 continue; 069 Enrollment e = assignment.getValue(request); 070 if (e == null) 071 continue; 072 if (enrollment.isOverlapping(e)) 073 conflicts.add(e); 074 } 075 076 // if this enrollment cannot be assigned (student already has a full 077 // schedule) -> unassignd a lowest priority request 078 if (!enrollment.getAssignments().isEmpty() && !enrollment.getStudent().canAssign(assignment, enrollment.getRequest())) { 079 Enrollment lowestPriorityEnrollment = null; 080 int lowestPriority = -1; 081 for (Request request : variables()) { 082 if (request.equals(enrollment.getRequest())) 083 continue; 084 Enrollment e = assignment.getValue(request); 085 if (e == null) 086 continue; 087 if (lowestPriority < request.getPriority()) { 088 lowestPriority = request.getPriority(); 089 lowestPriorityEnrollment = e; 090 } 091 } 092 if (lowestPriorityEnrollment != null) 093 conflicts.add(lowestPriorityEnrollment); 094 } 095 } 096 097 /** Two enrollments are consistent if they are not overlapping in time */ 098 @Override 099 public boolean isConsistent(Enrollment e1, Enrollment e2) { 100 return !e1.isOverlapping(e2); 101 } 102 103 /** 104 * A given enrollment is conflicting when the student is enrolled into 105 * another course / free time request that has an assignment that is 106 * overlapping with one or more assignments of the given section. See 107 * {@link Enrollment#isOverlapping(Enrollment)} for more details. 108 * 109 * @param enrollment 110 * {@link Enrollment} that is being considered 111 * @return true, if the student is enrolled into another enrollment of a 112 * different request that is overlapping in time with the given 113 * enrollment 114 */ 115 @Override 116 public boolean inConflict(Assignment<Request, Enrollment> assignment, Enrollment enrollment) { 117 // for all assigned course requests -> if overlapping with this 118 // enrollment -> conflict 119 for (Request request : variables()) { 120 if (request.equals(enrollment.getRequest())) 121 continue; 122 Enrollment e = assignment.getValue(request); 123 if (e == null) 124 continue; 125 if (enrollment.isOverlapping(e)) 126 return true; 127 } 128 129 // if this enrollment cannot be assigned (student already has a full 130 // schedule) -> conflict 131 if (!enrollment.getStudent().canAssign(assignment, enrollment.getRequest())) 132 return true; 133 134 // nothing above -> no conflict 135 return false; 136 } 137 138 @Override 139 public String toString() { 140 return "StudentConflicts"; 141 } 142}