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 * @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 AssignmentContextHolderMap<V extends Variable<V, T>, T extends Value<V, T>> implements AssignmentContextHolder<V, T> {
039    protected Map<Integer,AssignmentContext> iContexts = new HashMap<Integer, AssignmentContext>();
040
041    public AssignmentContextHolderMap() {
042    }
043
044    @Override
045    @SuppressWarnings("unchecked")
046    public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference) {
047        U context = (U) iContexts.get(reference.getIndex());
048        if (context != null) return context;
049        
050        context = reference.getParent().createAssignmentContext(assignment);
051        iContexts.put(reference.getIndex(), context);
052        return context;
053    }
054    
055    @Override
056    public <C extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, C> reference) {
057        iContexts.remove(reference.getIndex());
058    }
059
060}