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}