    001package org.cpsolver.ifs.assignment;
    002
    003import java.util.Collection;
    004import java.util.HashMap;
    005import java.util.HashSet;
    006import java.util.LinkedHashMap;
    007import java.util.Map;
    008import java.util.Set;
    009
    010import org.cpsolver.ifs.assignment.context.InheritedAssignmentContextHolder;
    011import org.cpsolver.ifs.model.Value;
    012import org.cpsolver.ifs.model.Variable;
    013import org.cpsolver.ifs.solution.Solution;
    014
    015
    016/**
    017 * Optimistic inherited assignment. This assignment does not expect the parent assignment to change
    018 * much and it only remembers local changes made in this assignment. Use with caution.
    019 *
    020 * @see InheritedAssignment
    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 OptimisticInheritedAssignment<V extends Variable<V, T>, T extends Value<V, T>> extends AssignmentAbstract<V, T> implements InheritedAssignment<V, T> {
    043    private Assignment<V, T> iParent;
    044    private Map<V, T> iAssignments = new LinkedHashMap<V, T>();
    045    private Set<V> iDirty = new HashSet<V>();
    046    private Map<V, Long> iIteration = new HashMap<V, Long>();
    047    private long iVersion = -1;
    048
    049    public OptimisticInheritedAssignment(Solution<V, T> parent, int index) {
    050        // super(new InheritedAssignmentContextHolder<V, T>(index, parent.getIteration()), index, parent);
    051        super(new InheritedAssignmentContextHolder<V, T>(index, parent.getIteration()));
    052        iParent = parent.getAssignment();
    053        iVersion = parent.getIteration();
    054    }
    055
    056    @Override
    057    public long getIteration(V variable) {
    058        Long it = iIteration.get(variable);
    059        return (it != null ? it : iDirty.contains(variable) ? 0 : iParent.getIteration(variable));
    060    }
    061
    062    @Override
    063    public Collection<V> assignedVariables() {
    064        Set<V> variables = new HashSet<V>(iParent.assignedVariables());
    065        variables.removeAll(iDirty);
    066        variables.addAll(iAssignments.keySet());
    067        return variables;
    068    }
    069
    070    @Override
    071    public Collection<T> assignedValues() {
    072        Set<T> values = new HashSet<T>();
    073        for (T val: iParent.assignedValues()) {
    074            if (val != null && !iDirty.contains(val.variable()))
    075                values.add(val);
    076        }
    077        values.addAll(iAssignments.values());
    078        return values;
    079    }
    080
    081    @Override
    082    public int nrAssignedVariables() {
    083        return iAssignments.size() + iParent.nrAssignedVariables() - iDirty.size();
    084    }
    085
    086    @Override
    087    protected T getValueInternal(V variable) {
    088        T value = (iAssignments.isEmpty() ? null : iAssignments.get(variable));
    089        return (value != null ? value : iDirty.contains(variable) ? null : iParent.getValue(variable));
    090   }
    091
    092    @Override
    093    protected void setValueInternal(long iteration, V variable, T value) {
    094        if (value == null) {
    095            iAssignments.remove(variable);
    096            iIteration.remove(variable);
    097            if (iParent.getValue(variable) != null)
    098                iDirty.add(variable);
    099        } else {
    100            iAssignments.put(variable, value);
    101            if (iteration > 0)
    102                iIteration.put(variable, iteration);
    103            iDirty.remove(variable);
    104        }
    105    }
    106
    107    @Override
    108    public Assignment<V, T> getParentAssignment() {
    109        return iParent;
    110    }
    111
    112    @Override
    113    public long getVersion() {
    114        return iVersion;
    115    }
    116}