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