001package org.cpsolver.ifs.assignment.context;
002
003import org.cpsolver.ifs.assignment.Assignment;
004import org.cpsolver.ifs.assignment.DefaultParallelAssignment;
005import org.cpsolver.ifs.model.Value;
006import org.cpsolver.ifs.model.Variable;
007
008
009/**
010 * A simple assignment context holder implementation used by the {@link DefaultParallelAssignment} class.
011 * {@link CanHoldContext} are used when possible, storing contexts in arrays, on the
012 * {@link DefaultParallelAssignment#getIndex()} position.
013 * 
014 * @see AssignmentContext
015 * @see AssignmentContextReference
016 * @see AssignmentContextHolder
017 * 
018 * @version IFS 1.3 (Iterative Forward Search)<br>
019 *          Copyright (C) 2014 Tomáš Müller<br>
020 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
021 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
022 * <br>
023 *          This library is free software; you can redistribute it and/or modify
024 *          it under the terms of the GNU Lesser General Public License as
025 *          published by the Free Software Foundation; either version 3 of the
026 *          License, or (at your option) any later version. <br>
027 * <br>
028 *          This library is distributed in the hope that it will be useful, but
029 *          WITHOUT ANY WARRANTY; without even the implied warranty of
030 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
031 *          Lesser General Public License for more details. <br>
032 * <br>
033 *          You should have received a copy of the GNU Lesser General Public
034 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
035 * @param <V> Variable
036 * @param <T> Value
037 **/
038public class DefaultParallelAssignmentContextHolder<V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentContextHolderMap<V, T> {
039    protected int iIndex = -1;
040
041    public DefaultParallelAssignmentContextHolder(int threadIndex) {
042        iIndex = threadIndex;
043    }
044    
045    @Override
046    @SuppressWarnings("unchecked")
047    public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference) {
048        if (iIndex >= 0 && iIndex < CanHoldContext.sMaxSize && reference.getParent() instanceof CanHoldContext) {
049            AssignmentContext[] contexts = ((CanHoldContext)reference.getParent()).getContext();
050            U context = (U)contexts[iIndex];
051            
052            if (context == null) {
053                context = reference.getParent().createAssignmentContext(assignment);
054                contexts[iIndex] = context;
055            }
056            
057            return context;
058        } else {
059            return super.getAssignmentContext(assignment, reference);
060        }
061    }
062    
063    @Override
064    public <C extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, C> reference) {
065        if (iIndex >= 0 && iIndex < CanHoldContext.sMaxSize && reference.getParent() instanceof CanHoldContext) {
066            AssignmentContext[] contexts = ((CanHoldContext)reference.getParent()).getContext();
067            contexts[iIndex] = null;
068        } else {
069            super.clearContext(reference);
070        }
071    }
072}