    001package org.cpsolver.ifs.assignment.context;
    002
    003import org.cpsolver.ifs.assignment.Assignment;
    004import org.cpsolver.ifs.criteria.AbstractCriterion;
    005import org.cpsolver.ifs.model.Model;
    006import org.cpsolver.ifs.model.Value;
    007import org.cpsolver.ifs.model.Variable;
    008
    009/**
    010 * An interface to be implemented by a class that need an assignment context associated with it.
    011 * I.e., for each existing assignment, there can be an instance of {@link AssignmentContext} available
    012 * to the class.<br><br>
    013 *
    014 * The idea is that each class that needs to keep some assignment dependent data will implements
    015 * {@link HasAssignmentContext} interface and the data will be wrapped by this class.
    016 * The {@link HasAssignmentContext} will only contain a reference to this
    017 * assignment context, created by calling {@link Model#createReference(HasAssignmentContext)}
    018 * during its initialization. The assignment context can be than accessed by calling
    019 * {@link Assignment#getAssignmentContext(AssignmentContextReference)}.<br><br>
    020 *
    021 * These assignment contexts are being held in memory by a class implementing the
    022 * {@link AssignmentContextHolder} interface. For constraints, criteria, extensions, and
    023 * neighborhood selections an existing class implementing the context can be used, see
    024 * {@link ConstraintWithContext}, {@link AbstractCriterion}, {@link ExtensionWithContext},
    025 * and {@link NeighbourSelectionWithContext} respectively.<br><br>
    026 *
    027 * For instance, when implementing {@link ConstraintWithContext}, only the method
    028 * {@link ConstraintWithContext#createAssignmentContext(Assignment)} needs to be implemented and the
    029 * assignment context can be accessed within the constraint using the method
    030 * {@link ConstraintWithContext#getContext(Assignment)}.
    031 *
    032 * @see AssignmentContextHolder
    033 * @see HasAssignmentContext
    034 *
    035 * @version IFS 1.3 (Iterative Forward Search)<br>
    036 *          Copyright (C) 2014 Tomáš Müller<br>
    037 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    038 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    039 * <br>
    040 *          This library is free software; you can redistribute it and/or modify
    041 *          it under the terms of the GNU Lesser General Public License as
    042 *          published by the Free Software Foundation; either version 3 of the
    043 *          License, or (at your option) any later version. <br>
    044 * <br>
    045 *          This library is distributed in the hope that it will be useful, but
    046 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    047 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    048 *          Lesser General Public License for more details. <br>
    049 * <br>
    050 *          You should have received a copy of the GNU Lesser General Public
    051 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
    052 * @param <V> Variable
    053 * @param <T> Value
    054 * @param <C> Assignment Context
    055 **/
    056public interface HasAssignmentContext <V extends Variable<V, T>, T extends Value<V, T>, C extends AssignmentContext> {
    057
    058    /**
    059     * Create a new assignment context for the given assignment. If there are already some variables assigned in
    060     * the value, the method should make sure that the context is appropriately initialized.
    061     * @param assignment an assignment for which there needs to be an assignment context
    062     * @return a new instance of the assignment context, filled according to the given assignment
    063     */
    064    public C createAssignmentContext(Assignment<V,T> assignment);
    065
    066    /**
    067     * Returns an assignment context reference
    068     * @return reference provided by the model by calling {@link Model#createReference(HasAssignmentContext)} during initialization
    069     */
    070    public AssignmentContextReference<V, T, C> getAssignmentContextReference();
    071
    072    /**
    073     * Store an assignment context reference that was given for the class by the {@link Model#createReference(HasAssignmentContext)}.
    074     * @param reference reference provided by the model by calling {@link Model#createReference(HasAssignmentContext)} during initialization
    075     */
    076    public void setAssignmentContextReference(AssignmentContextReference<V, T, C> reference);
    077
    078    /**
    079     * Returns an assignment context associated with this object. If there is no
    080     * assignment context associated with this object yet, one is created using the
    081     * {@link ConstraintWithContext#createAssignmentContext(Assignment)} method.
    082     * @param assignment given assignment
    083     * @return assignment context associated with this object and the given assignment
    084     */
    085    public C getContext(Assignment<V, T> assignment);
    086}