001package org.cpsolver.ifs.assignment;
002
003import java.util.Collection;
004import java.util.HashMap;
005import java.util.LinkedHashMap;
006import java.util.Map;
007
008import org.cpsolver.ifs.assignment.context.AssignmentContextHolder;
009import org.cpsolver.ifs.assignment.context.AssignmentContextHolderMap;
010import org.cpsolver.ifs.model.Value;
011import org.cpsolver.ifs.model.Variable;
012
013
014/**
015 * An assignment using a {@link HashMap} to store values of all the variables of the model.
016 * This class is slower to store and retrieve a value than {@link AssignmentArray}, but 
017 * faster in retrieving a collection of assigned variables and values (methods 
018 * {@link Assignment#assignedVariables()} and {@link Assignment#assignedValues()}). 
019 * 
020 * @see Assignment
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 **/
042public class AssignmentMap<V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentAbstract<V, T> {
043    private Map<V, T> iAssignments = new LinkedHashMap<V, T>();
044    private Map<V, Long> iIteration = new HashMap<V, Long>();
045    
046    /** Creates an empty assignment 
047     * @param contexts assignment context holder
048     **/
049    public AssignmentMap(AssignmentContextHolder<V, T> contexts) {
050        super(contexts);
051    }
052    
053    /** Creates an empty assignment */
054    public AssignmentMap() {
055        this(new AssignmentContextHolderMap<V, T>());
056    }
057    
058    /** Creates a copy of an existing assignment
059     * @param assignment current assignment
060     **/
061    public AssignmentMap(Assignment<V, T> assignment) {
062        super(new AssignmentContextHolderMap<V, T>());
063        for (T value: assignment.assignedValues())
064            iAssignments.put(value.variable(), value);
065    }
066
067    
068    @Override
069    public long getIteration(V variable) {
070        Long it = iIteration.get(variable);
071        return (it == null ? 0 : it);
072    }
073
074    @Override
075    public Collection<V> assignedVariables() {
076        return iAssignments.keySet();
077    }
078    
079    @Override
080    public Collection<T> assignedValues() {
081        return iAssignments.values();
082    }
083
084    @Override
085    public int nrAssignedVariables() {
086        return iAssignments.size();
087    }
088    
089    @Override
090    protected T getValueInternal(V variable) {
091        return iAssignments.get(variable);
092   }
093
094    @Override
095    protected void setValueInternal(long iteration, V variable, T value) {
096        if (value == null) {
097            iAssignments.remove(variable);
098            iIteration.remove(variable);
099        } else {
100            iAssignments.put(variable, value);
101            if (iteration > 0)
102                iIteration.put(variable, iteration);
103        }
104    }
105}