001package org.cpsolver.ifs.assignment;
002
003import java.util.Collection;
004import java.util.HashSet;
005import java.util.Set;
006
007import org.cpsolver.ifs.assignment.context.DefaultSingleAssignmentContextHolder;
008import org.cpsolver.ifs.model.Model;
009import org.cpsolver.ifs.model.Value;
010import org.cpsolver.ifs.model.Variable;
011import org.cpsolver.ifs.solver.Solver;
012
013
014/**
015 * An assignment using the old {@link Variable#getAssignment()} to store values of all the
016 * variables of the model. Besides of that, a set of assigned variables is kept in memory.
017 * It is fast, but there can be only one such assignment at a time.
018 * Ideal for single threaded solvers. Also used as a default assignment, see
019 * {@link Model#getDefaultAssignment()}. Used by {@link Solver} where there is only one
020 * assignment kept in memory.
021 * 
022 * @see Assignment
023 * @see Solver
024 * 
025 * @version IFS 1.3 (Iterative Forward Search)<br>
026 *          Copyright (C) 2014 Tomáš Müller<br>
027 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
028 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
029 * <br>
030 *          This library is free software; you can redistribute it and/or modify
031 *          it under the terms of the GNU Lesser General Public License as
032 *          published by the Free Software Foundation; either version 3 of the
033 *          License, or (at your option) any later version. <br>
034 * <br>
035 *          This library is distributed in the hope that it will be useful, but
036 *          WITHOUT ANY WARRANTY; without even the implied warranty of
037 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
038 *          Lesser General Public License for more details. <br>
039 * <br>
040 *          You should have received a copy of the GNU Lesser General Public
041 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
042 * @param <V> Variable
043 * @param <T> Value
044 **/
045public class DefaultSingleAssignment<V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentAbstract<V, T> {
046    private Set<V> iAssignedVariables = new HashSet<V>();
047
048    public DefaultSingleAssignment() {
049        super(new DefaultSingleAssignmentContextHolder<V,T>());
050    }
051
052    @Override
053    @SuppressWarnings("deprecation")
054    public long getIteration(V variable) {
055        return variable.getLastIteration();
056    }
057
058    @Override
059    public Collection<V> assignedVariables() {
060        return iAssignedVariables;
061    }
062
063    @Override
064    @SuppressWarnings("deprecation")
065    protected T getValueInternal(V variable) {
066        return variable.getAssignment();
067    }
068
069    @Override
070    @SuppressWarnings("deprecation")
071    protected void setValueInternal(long iteration, V variable, T value) {
072        variable.setAssignment(value);
073        variable.setLastIteration(iteration);
074        if (value == null)
075            iAssignedVariables.remove(variable);
076        else
077            iAssignedVariables.add(variable);
078    }
079    
080    @Override
081    public int getIndex() {
082        return 0;
083    }
084}