    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 * @author  Tomáš Müller
    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 DefaultSingleAssignmentContextHolder<V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentContextHolderMap<V, T> {
    039
    040    public DefaultSingleAssignmentContextHolder() {
    041    }
    042
    043    @Override
    044    @SuppressWarnings("unchecked")
    045    public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference) {
    046        if (reference.getParent() instanceof CanHoldContext) {
    047            AssignmentContext[] contexts = ((CanHoldContext)reference.getParent()).getContext();
    048            if (contexts[0] == null)
    049                contexts[0] = reference.getParent().createAssignmentContext(assignment);
    050            return (U)contexts[0];
    051        } else {
    052            return super.getAssignmentContext(assignment, reference);
    053        }
    054    }
    055
    056    @Override
    057    public <C extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, C> reference) {
    058        if (reference.getParent() instanceof CanHoldContext) {
    059            AssignmentContext[] contexts = ((CanHoldContext)reference.getParent()).getContext();
    060            contexts[0] = null;
    061        } else {
    062            super.clearContext(reference);
    063        }
    064    }
    065}