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