    001package org.cpsolver.ifs.assignment.context;
    002
    003import org.cpsolver.ifs.assignment.Assignment;
    004import org.cpsolver.ifs.model.Constraint;
    005import org.cpsolver.ifs.model.Model;
    006import org.cpsolver.ifs.model.Value;
    007import org.cpsolver.ifs.model.Variable;
    008
    009/**
    010 * A constraint with an assignment context. In order to be able to hold multiple assignments in memory
    011 * it is desired for all the assignment dependent data a constraint may need (to effectively enumerate
    012 * conflicting values), to store these data in a separate class (implementing the
    013 * {@link AssignmentConstraintContext} interface). This context is created by calling
    014 * {@link ConstraintWithContext#createAssignmentContext(Assignment)} and accessed by
    015 * {@link ConstraintWithContext#getContext(Assignment)}.
    016 *
    017 *
    018 * @see AssignmentContext
    019 *
    020 * @version IFS 1.3 (Iterative Forward Search)<br>
    021 *          Copyright (C) 2014 Tomáš Müller<br>
    022 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    023 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    024 * <br>
    025 *          This library is free software; you can redistribute it and/or modify
    026 *          it under the terms of the GNU Lesser General Public License as
    027 *          published by the Free Software Foundation; either version 3 of the
    028 *          License, or (at your option) any later version. <br>
    029 * <br>
    030 *          This library is distributed in the hope that it will be useful, but
    031 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    032 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    033 *          Lesser General Public License for more details. <br>
    034 * <br>
    035 *          You should have received a copy of the GNU Lesser General Public
    036 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
    037 * @param <V> Variable
    038 * @param <T> Value
    039 * @param <C> Assignment Context
    040 **/
    041public abstract class ConstraintWithContext<V extends Variable<V, T>, T extends Value<V, T>, C extends AssignmentConstraintContext<V, T>> extends Constraint<V, T> implements HasAssignmentContext<V, T, C>, CanHoldContext {
    042    private AssignmentContextReference<V, T, C> iContextReference = null;
    043    private AssignmentContext[] iContext = new AssignmentContext[CanHoldContext.sMaxSize];
    044
    045    public ConstraintWithContext() {
    046        super();
    047    }
    048
    049    @Override
    050    public void setModel(Model<V, T> model) {
    051        super.setModel(model);
    052        if (model != null)
    053            iContextReference = model.createReference(this);
    054    }
    055
    056    /**
    057     * Returns an assignment context associated with this constraint. If there is no
    058     * assignment context associated with this constraint yet, one is created using the
    059     * {@link ConstraintWithContext#createAssignmentContext(Assignment)} method. From that time on,
    060     * this context is kept with the assignment and automatically updated by calling the
    061     * {@link AssignmentConstraintContext#assigned(Assignment, Value)} and {@link AssignmentConstraintContext#unassigned(Assignment, Value)}
    062     * whenever a variable of this constraint is changed.
    063     * @param assignment given assignment
    064     * @return assignment context associated with this constraint and the given assignment
    065     */
    066    @Override
    067    public C getContext(Assignment<V, T> assignment) {
    068        return AssignmentContextHelper.getContext(this, assignment);
    069    }
    070
    071    @Override
    072    public AssignmentContextReference<V, T, C> getAssignmentContextReference() { return iContextReference; }
    073
    074    @Override
    075    public void setAssignmentContextReference(AssignmentContextReference<V, T, C> reference) { iContextReference = reference; }
    076
    077    @Override
    078    public AssignmentContext[] getContext() { return iContext; }
    079
    080    @Override
    081    public void assigned(Assignment<V, T> assignment, long iteration, T value) {
    082        super.assigned(assignment, iteration, value);
    083        getContext(assignment).assigned(assignment, value);
    084    }
    085
    086    @Override
    087    public void unassigned(Assignment<V, T> assignment, long iteration, T value) {
    088        super.unassigned(assignment, iteration, value);
    089        getContext(assignment).unassigned(assignment, value);
    090    }
    091}