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