001package org.cpsolver.ifs.assignment.context; 002 003import org.cpsolver.ifs.assignment.Assignment; 004import org.cpsolver.ifs.assignment.DefaultSingleAssignment; 005import org.cpsolver.ifs.model.Value; 006import org.cpsolver.ifs.model.Variable; 007 008/** 009 * A simple assignment context holder implementation used by the {@link DefaultSingleAssignment} class. 010 * {@link CanHoldContext} are used when possible, storing contexts in arrays of length 1 (one context per 011 * {@link HasAssignmentContext} class). 012 * 013 * @see AssignmentContext 014 * @see AssignmentContextReference 015 * @see AssignmentContextHolder 016 * 017 * @version IFS 1.3 (Iterative Forward Search)<br> 018 * Copyright (C) 2014 Tomas Muller<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 <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>. 034 * @param <V> Variable 035 * @param <T> Value 036 **/ 037public class DefaultSingleAssignmentContextHolder<V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentContextHolderMap<V, T> { 038 039 public DefaultSingleAssignmentContextHolder() { 040 } 041 042 @Override 043 @SuppressWarnings("unchecked") 044 public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference) { 045 if (reference.getParent() instanceof CanHoldContext) { 046 CanHoldContext holder = (CanHoldContext)reference.getParent(); 047 AssignmentContext[] contexts = holder.getContext(); 048 if (contexts != null) 049 return (U) contexts[0]; 050 051 U context = reference.getParent().createAssignmentContext(assignment); 052 holder.setContext(new AssignmentContext[] {context}); 053 054 return context; 055 } else { 056 return super.getAssignmentContext(assignment, reference); 057 } 058 } 059 060 @Override 061 public <C extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, C> reference) { 062 if (reference.getParent() instanceof CanHoldContext) { 063 CanHoldContext holder = (CanHoldContext)reference.getParent(); 064 holder.setContext(null); 065 } else { 066 super.clearContext(reference); 067 } 068 } 069}