001package org.cpsolver.ifs.assignment.context;
002
003import org.cpsolver.ifs.assignment.Assignment;
004import org.cpsolver.ifs.model.Model;
005import org.cpsolver.ifs.model.Value;
006import org.cpsolver.ifs.model.Variable;
007
008/**
009 * An interface holding all assignment contexts associated with one assignment. It also
010 * creates a new assignment context when there is no assignment context associated with the given
011 * reference.<br><br>
012 * 
013 * Method {@link AssignmentContextReference#getIndex()} can be used to index stored contexts. 
014 * A new assignment context can be created for a reference by calling {@link HasAssignmentContext#createAssignmentContext(Assignment)}
015 * on the {@link AssignmentContextReference#getParent()}.
016 * 
017 * @see AssignmentContext
018 * @see AssignmentContextReference
019 * @see HasAssignmentContext
020 * 
021 * @author  Tomáš Müller
022 * @version IFS 1.3 (Iterative Forward Search)<br>
023 *          Copyright (C) 2014 Tomáš Müller<br>
024 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
025 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
026 * <br>
027 *          This library is free software; you can redistribute it and/or modify
028 *          it under the terms of the GNU Lesser General Public License as
029 *          published by the Free Software Foundation; either version 3 of the
030 *          License, or (at your option) any later version. <br>
031 * <br>
032 *          This library is distributed in the hope that it will be useful, but
033 *          WITHOUT ANY WARRANTY; without even the implied warranty of
034 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
035 *          Lesser General Public License for more details. <br>
036 * <br>
037 *          You should have received a copy of the GNU Lesser General Public
038 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
039 * @param <V> Variable
040 * @param <T> Value
041 **/
042public interface AssignmentContextHolder<V extends Variable<V, T>, T extends Value<V, T>> {
043
044    /**
045     * Return assignment context for the given assignment and reference. A new assignment context is created
046     * when there is not assignment context associated with the given reference yet.
047     * @param assignment current assignment (there is only one assignment associated with one holder, but 
048     * the assignment is passed so that {@link HasAssignmentContext#createAssignmentContext(Assignment)} can be called if needed
049     * @param reference a reference created by calling {@link Model#createReference(HasAssignmentContext)} 
050     * @param <U> assignment context type
051     * @return an assignment context
052     */
053    public <U extends AssignmentContext> U getAssignmentContext(Assignment<V, T> assignment, AssignmentContextReference<V, T, U> reference);
054    
055    /**
056     * Clear an assignment context that is associated with the given a reference. If there is any created for the reference.
057     * @param reference a reference (which can be stored within the model, e.g., as an instance variable of a constraint)
058     * @param <U> assignment context type
059     **/
060    public <U extends AssignmentContext> void clearContext(AssignmentContextReference<V, T, U> reference);
061
062}