001package org.cpsolver.ifs.assignment.context; 002 003import org.cpsolver.ifs.assignment.Assignment; 004import org.cpsolver.ifs.model.Constraint; 005import org.cpsolver.ifs.model.Model; 006import org.cpsolver.ifs.model.Value; 007import org.cpsolver.ifs.model.Variable; 008 009/** 010 * A constraint with an assignment context. In order to be able to hold multiple assignments in memory 011 * it is desired for all the assignment dependent data a constraint may need (to effectively enumerate 012 * conflicting values), to store these data in a separate class (implementing the 013 * {@link AssignmentConstraintContext} interface). This context is created by calling 014 * {@link ConstraintWithContext#createAssignmentContext(Assignment)} and accessed by 015 * {@link ConstraintWithContext#getContext(Assignment)}. 016 * 017 * 018 * @see AssignmentContext 019 * 020 * @version IFS 1.3 (Iterative Forward Search)<br> 021 * Copyright (C) 2014 Tomáš Müller<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 <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>. 037 * @param <V> Variable 038 * @param <T> Value 039 * @param <C> Assignment Context 040 **/ 041public abstract class ConstraintWithContext<V extends Variable<V, T>, T extends Value<V, T>, C extends AssignmentConstraintContext<V, T>> extends Constraint<V, T> implements HasAssignmentContext<V, T, C>, CanHoldContext { 042 private AssignmentContextReference<V, T, C> iContextReference = null; 043 private AssignmentContext[] iContext = new AssignmentContext[CanHoldContext.sMaxSize]; 044 045 public ConstraintWithContext() { 046 super(); 047 } 048 049 @Override 050 public void setModel(Model<V, T> model) { 051 super.setModel(model); 052 if (model != null) 053 iContextReference = model.createReference(this); 054 } 055 056 /** 057 * Returns an assignment context associated with this constraint. If there is no 058 * assignment context associated with this constraint yet, one is created using the 059 * {@link ConstraintWithContext#createAssignmentContext(Assignment)} method. From that time on, 060 * this context is kept with the assignment and automatically updated by calling the 061 * {@link AssignmentConstraintContext#assigned(Assignment, Value)} and {@link AssignmentConstraintContext#unassigned(Assignment, Value)} 062 * whenever a variable of this constraint is changed. 063 * @param assignment given assignment 064 * @return assignment context associated with this constraint and the given assignment 065 */ 066 @Override 067 public C getContext(Assignment<V, T> assignment) { 068 return AssignmentContextHelper.getContext(this, assignment); 069 } 070 071 @Override 072 public AssignmentContextReference<V, T, C> getAssignmentContextReference() { return iContextReference; } 073 074 @Override 075 public void setAssignmentContextReference(AssignmentContextReference<V, T, C> reference) { iContextReference = reference; } 076 077 @Override 078 public AssignmentContext[] getContext() { return iContext; } 079 080 @Override 081 public void assigned(Assignment<V, T> assignment, long iteration, T value) { 082 super.assigned(assignment, iteration, value); 083 getContext(assignment).assigned(assignment, value); 084 } 085 086 @Override 087 public void unassigned(Assignment<V, T> assignment, long iteration, T value) { 088 super.unassigned(assignment, iteration, value); 089 getContext(assignment).unassigned(assignment, value); 090 } 091}