    001package org.cpsolver.ifs.assignment.context;
    002
    003import java.util.Arrays;
    004
    005import org.cpsolver.ifs.assignment.Assignment;
    006import org.cpsolver.ifs.model.Value;
    007import org.cpsolver.ifs.model.Variable;
    008
    009
    010/**
    011 * A simple assignment context holder implementation using array to store all the assignment contexts.
    012 * {@link AssignmentContextReference#getIndex()} are used to index the array.
    013 *
    014 * @see AssignmentContext
    015 * @see AssignmentContextReference
    016 *
    017 * @version IFS 1.3 (Iterative Forward Search)<br>
    018 *          Copyright (C) 2014 Tomáš Müller<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 AssignmentContextHolderArray<V extends Variable<V, T>, T extends Value<V, T>> implements AssignmentContextHolder<V, T> {
    038    private AssignmentContext[] iContexts = new AssignmentContext[1000];
    039
    040    public AssignmentContextHolderArray() {
    041    }
    042
    043    @Override
    044    @SuppressWarnings("unchecked")
    045    public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference) {
    046        try {
    047            AssignmentContext context = iContexts[reference.getIndex()];
    048            if (context != null) return (U) context;
    049        } catch (ArrayIndexOutOfBoundsException e) {}
    050
    051        U context = reference.getParent().createAssignmentContext(assignment);
    052        if (iContexts.length <= reference.getIndex())
    053            iContexts = Arrays.copyOf(iContexts, reference.getIndex() + 1000);
    054        iContexts[reference.getIndex()] = context;
    055        return context;
    056    }
    057
    058    @Override
    059    public <C extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, C> reference) {
    060        try {
    061            iContexts[reference.getIndex()] = null;
    062        } catch (ArrayIndexOutOfBoundsException e) {}
    063    }
    064}