001package org.cpsolver.ifs.assignment.context;
002
003import java.util.HashMap;
004import java.util.Map;
005
006import org.cpsolver.ifs.assignment.Assignment;
007import org.cpsolver.ifs.model.Value;
008import org.cpsolver.ifs.model.Variable;
009
010
011/**
012 * A simple assignment context holder implementation using {@link HashMap} to store all the assignment contexts.
013 * {@link AssignmentContextReference#getIndex()} are used to index the map.
014 * 
015 * @see AssignmentContext
016 * @see AssignmentContextReference
017 * 
018 * @author  Tomáš Müller
019 * @version IFS 1.3 (Iterative Forward Search)<br>
020 *          Copyright (C) 2014 Tomáš Müller<br>
021 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
022 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
023 * <br>
024 *          This library is free software; you can redistribute it and/or modify
025 *          it under the terms of the GNU Lesser General Public License as
026 *          published by the Free Software Foundation; either version 3 of the
027 *          License, or (at your option) any later version. <br>
028 * <br>
029 *          This library is distributed in the hope that it will be useful, but
030 *          WITHOUT ANY WARRANTY; without even the implied warranty of
031 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
032 *          Lesser General Public License for more details. <br>
033 * <br>
034 *          You should have received a copy of the GNU Lesser General Public
035 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
036 * @param <V> Variable
037 * @param <T> Value
038 **/
039public class AssignmentContextHolderMap<V extends Variable<V, T>, T extends Value<V, T>> implements AssignmentContextHolder<V, T> {
040    protected Map<Integer,AssignmentContext> iContexts = new HashMap<Integer, AssignmentContext>();
041
042    public AssignmentContextHolderMap() {
043    }
044
045    @Override
046    @SuppressWarnings("unchecked")
047    public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference) {
048        U context = (U) iContexts.get(reference.getIndex());
049        if (context != null) return context;
050        
051        context = reference.getParent().createAssignmentContext(assignment);
052        iContexts.put(reference.getIndex(), context);
053        return context;
054    }
055    
056    @Override
057    public <C extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, C> reference) {
058        iContexts.remove(reference.getIndex());
059    }
060
061}