    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 * A reference to an assignment context. A reference is created by a class requiring an assignment
    010 * context {@link HasAssignmentContext} by calling {@link Model#createReference(HasAssignmentContext)}.
    011 * This reference can be stored with the class implementing the {@link HasAssignmentContext}
    012 * interface in place of the assignment context {@link AssignmentContext}. Assignment context
    013 * can be than retrieved from an assignment by calling {@link Assignment#getAssignmentContext(AssignmentContextReference)}.
    014 * This method also create a new context if there is none associated with the assignment yet for
    015 * the given reference.
    016 *
    017 * <br><br>
    018 *
    019 * Method {@link AssignmentContextReference#getIndex()} can be used to index stored contexts.
    020 * A new assignment context can be created for a reference by calling {@link HasAssignmentContext#createAssignmentContext(Assignment)}
    021 * on the {@link AssignmentContextReference#getParent()}.
    022 *
    023 * @see AssignmentContext
    024 * @see AssignmentContextReference
    025 * @see HasAssignmentContext
    026 *
    027 * @version IFS 1.3 (Iterative Forward Search)<br>
    028 *          Copyright (C) 2014 Tomáš Müller<br>
    029 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    030 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    031 * <br>
    032 *          This library is free software; you can redistribute it and/or modify
    033 *          it under the terms of the GNU Lesser General Public License as
    034 *          published by the Free Software Foundation; either version 3 of the
    035 *          License, or (at your option) any later version. <br>
    036 * <br>
    037 *          This library is distributed in the hope that it will be useful, but
    038 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    039 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    040 *          Lesser General Public License for more details. <br>
    041 * <br>
    042 *          You should have received a copy of the GNU Lesser General Public
    043 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
    044 * @param <V> Variable
    045 * @param <T> Value
    046 * @param <C> Assignment Context
    047 **/
    048public class AssignmentContextReference <V extends Variable<V, T>, T extends Value<V, T>, C extends AssignmentContext> {
    049    private HasAssignmentContext<V, T, C> iParent;
    050    private int iIndex;
    051
    052    /**
    053     * Create a reference context
    054     * @param parent a class implementing the {@link HasAssignmentContext} interface
    055     * @param index a unique index associated with the reference by the {@link Model}
    056     **/
    057    public AssignmentContextReference(HasAssignmentContext<V, T, C> parent, int index) {
    058        iParent = parent;
    059        iIndex = index;
    060    }
    061
    062    /**
    063     * Return index, a unique number associated with the reference by the {@link Model}.
    064     * @return an index
    065     */
    066    public int getIndex() {
    067        return iIndex;
    068    }
    069
    070    @Override
    071    public int hashCode() {
    072        return iIndex;
    073    }
    074
    075    @Override
    076    public boolean equals(Object o) {
    077        if (o == null || !(o instanceof AssignmentContextReference<?,?,?>))
    078            return false;
    079        return getIndex() == ((AssignmentContextReference<?,?,?>)o).getIndex();
    080    }
    081
    082    /**
    083     * Return parent class, i.e., the class implementing the {@link HasAssignmentContext} interface.
    084     * @return parent
    085     */
    086    public HasAssignmentContext<V,T,C> getParent() {
    087        return iParent;
    088    }
    089}