    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 * @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 AssignmentContextHolderArray<V extends Variable<V, T>, T extends Value<V, T>> implements AssignmentContextHolder<V, T> {
    039    private AssignmentContext[] iContexts = new AssignmentContext[1000];
    040
    041    public AssignmentContextHolderArray() {
    042    }
    043
    044    @Override
    045    @SuppressWarnings("unchecked")
    046    public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference) {
    047        try {
    048            AssignmentContext context = iContexts[reference.getIndex()];
    049            if (context != null) return (U) context;
    050        } catch (ArrayIndexOutOfBoundsException e) {}
    051
    052        U context = reference.getParent().createAssignmentContext(assignment);
    053        if (iContexts.length <= reference.getIndex())
    054            iContexts = Arrays.copyOf(iContexts, reference.getIndex() + 1000);
    055        iContexts[reference.getIndex()] = context;
    056        return context;
    057    }
    058
    059    @Override
    060    public <C extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, C> reference) {
    061        try {
    062            iContexts[reference.getIndex()] = null;
    063        } catch (ArrayIndexOutOfBoundsException e) {}
    064    }
    065}