    001package org.cpsolver.ifs.assignment.context;
    002
    003import org.cpsolver.ifs.assignment.Assignment;
    004import org.cpsolver.ifs.model.BinaryConstraint;
    005import org.cpsolver.ifs.model.Model;
    006import org.cpsolver.ifs.model.Value;
    007import org.cpsolver.ifs.model.Variable;
    008
    009/**
    010 * A binary constraint with an assignment context. This is a variant of the {@link ConstraintWithContext} that extends the
    011 * {@link BinaryConstraint} class.
    012 *
    013 *
    014 * @see AssignmentContext
    015 *
    016 * @version IFS 1.3 (Iterative Forward Search)<br>
    017 *          Copyright (C) 2014 Tomáš Müller<br>
    018 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    019 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    020 * <br>
    021 *          This library is free software; you can redistribute it and/or modify
    022 *          it under the terms of the GNU Lesser General Public License as
    023 *          published by the Free Software Foundation; either version 3 of the
    024 *          License, or (at your option) any later version. <br>
    025 * <br>
    026 *          This library is distributed in the hope that it will be useful, but
    027 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    028 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    029 *          Lesser General Public License for more details. <br>
    030 * <br>
    031 *          You should have received a copy of the GNU Lesser General Public
    032 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
    033 * @param <V> Variable
    034 * @param <T> Value
    035 * @param <C> Assignment Context
    036 **/
    037public abstract class BinaryConstraintWithContext<V extends Variable<V, T>, T extends Value<V, T>, C extends AssignmentConstraintContext<V, T>> extends BinaryConstraint<V, T> implements HasAssignmentContext<V, T, C>, CanHoldContext {
    038    private AssignmentContextReference<V, T, C> iContextReference = null;
    039    private AssignmentContext[] iContext = new AssignmentContext[CanHoldContext.sMaxSize];
    040
    041    public BinaryConstraintWithContext() {
    042        super();
    043    }
    044
    045    @Override
    046    public void setModel(Model<V, T> model) {
    047        super.setModel(model);
    048        if (model != null)
    049            iContextReference = model.createReference(this);
    050    }
    051
    052    /**
    053     * Returns an assignment context associated with this constraint. If there is no
    054     * assignment context associated with this constraint yet, one is created using the
    055     * {@link ConstraintWithContext#createAssignmentContext(Assignment)} method. From that time on,
    056     * this context is kept with the assignment and automatically updated by calling the
    057     * {@link AssignmentConstraintContext#assigned(Assignment, Value)} and {@link AssignmentConstraintContext#unassigned(Assignment, Value)}
    058     * whenever a variable of this constraint is changed.
    059     * @param assignment given assignment
    060     * @return assignment context associated with this constraint and the given assignment
    061     */
    062    @Override
    063    public C getContext(Assignment<V, T> assignment) {
    064        return AssignmentContextHelper.getContext(this, assignment);
    065    }
    066
    067    @Override
    068    public AssignmentContextReference<V, T, C> getAssignmentContextReference() { return iContextReference; }
    069
    070    @Override
    071    public void setAssignmentContextReference(AssignmentContextReference<V, T, C> reference) { iContextReference = reference; }
    072
    073    @Override
    074    public AssignmentContext[] getContext() { return iContext; }
    075
    076    @Override
    077    public void assigned(Assignment<V, T> assignment, long iteration, T value) {
    078        super.assigned(assignment, iteration, value);
    079        getContext(assignment).assigned(assignment, value);
    080    }
    081
    082    @Override
    083    public void unassigned(Assignment<V, T> assignment, long iteration, T value) {
    084        super.unassigned(assignment, iteration, value);
    085        getContext(assignment).unassigned(assignment, value);
    086    }
    087}