    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 * @author  Tomáš Müller
    017 * @version IFS 1.3 (Iterative Forward Search)<br>
    018 *          Copyright (C) 2014 Tomáš Müller<br>
    019 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    020 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    021 * <br>
    022 *          This library is free software; you can redistribute it and/or modify
    023 *          it under the terms of the GNU Lesser General Public License as
    024 *          published by the Free Software Foundation; either version 3 of the
    025 *          License, or (at your option) any later version. <br>
    026 * <br>
    027 *          This library is distributed in the hope that it will be useful, but
    028 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    029 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    030 *          Lesser General Public License for more details. <br>
    031 * <br>
    032 *          You should have received a copy of the GNU Lesser General Public
    033 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
    034 * @param <V> Variable
    035 * @param <T> Value
    036 * @param <C> Assignment Context
    037 **/
    038public 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 {
    039    private AssignmentContextReference<V, T, C> iContextReference = null;
    040    private AssignmentContext[] iContext = new AssignmentContext[CanHoldContext.sMaxSize];
    041
    042    public BinaryConstraintWithContext() {
    043        super();
    044    }
    045
    046    @Override
    047    public void setModel(Model<V, T> model) {
    048        super.setModel(model);
    049        if (model != null)
    050            iContextReference = model.createReference(this);
    051    }
    052
    053    /**
    054     * Returns an assignment context associated with this constraint. If there is no
    055     * assignment context associated with this constraint yet, one is created using the
    056     * {@link ConstraintWithContext#createAssignmentContext(Assignment)} method. From that time on,
    057     * this context is kept with the assignment and automatically updated by calling the
    058     * {@link AssignmentConstraintContext#assigned(Assignment, Value)} and {@link AssignmentConstraintContext#unassigned(Assignment, Value)}
    059     * whenever a variable of this constraint is changed.
    060     * @param assignment given assignment
    061     * @return assignment context associated with this constraint and the given assignment
    062     */
    063    @Override
    064    public C getContext(Assignment<V, T> assignment) {
    065        return AssignmentContextHelper.getContext(this, assignment);
    066    }
    067
    068    @Override
    069    public AssignmentContextReference<V, T, C> getAssignmentContextReference() { return iContextReference; }
    070
    071    @Override
    072    public void setAssignmentContextReference(AssignmentContextReference<V, T, C> reference) { iContextReference = reference; }
    073
    074    @Override
    075    public AssignmentContext[] getContext() { return iContext; }
    076
    077    @Override
    078    public void assigned(Assignment<V, T> assignment, long iteration, T value) {
    079        super.assigned(assignment, iteration, value);
    080        getContext(assignment).assigned(assignment, value);
    081    }
    082
    083    @Override
    084    public void unassigned(Assignment<V, T> assignment, long iteration, T value) {
    085        super.unassigned(assignment, iteration, value);
    086        getContext(assignment).unassigned(assignment, value);
    087    }
    088}