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Open-source constraint solver.
There is a newer version: 4.10.16
/**
 * Copyright (c) 2016, Ecole des Mines de Nantes
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the .
 * 4. Neither the name of the  nor the
 *    names of its contributors may be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY  ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL  BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.chocosolver.solver.constraints.set;

import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.constraints.PropagatorPriority;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.SetVar;
import org.chocosolver.solver.variables.delta.ISetDeltaMonitor;
import org.chocosolver.solver.variables.events.SetEventType;
import org.chocosolver.util.ESat;
import org.chocosolver.util.procedure.IntProcedure;

/**
 * set2 is an offSet view of set1
 * x in set1 <=> x+offSet in set2
 *
 * @author Jean-Guillaume Fages
 */
public class PropOffSet extends Propagator {

    private int offSet, tmp;
    private SetVar tmpSet;
    private IntProcedure forced, removed;
    private ISetDeltaMonitor[] sdm;

    //***********************************************************************************
    // CONSTRUCTORS
    //***********************************************************************************

    /**
     * set2 is an offSet view of set1
     * x in set1 <=> x+offSet in set2
     */
    public PropOffSet(SetVar set1, SetVar set2, int offSet) {
        super(new SetVar[]{set1, set2}, PropagatorPriority.UNARY, true);
        this.offSet = offSet;
        sdm = new ISetDeltaMonitor[2];
        sdm[0] = vars[0].monitorDelta(this);
        sdm[1] = vars[1].monitorDelta(this);
        this.forced = i -> tmpSet.force(i + tmp, this);
        this.removed = i -> tmpSet.remove(i + tmp, this);
    }

    //***********************************************************************************
    // METHODS
    //***********************************************************************************

    @Override
    public void propagate(int evtmask) throws ContradictionException {
        // kernel
        for (int j : vars[0].getLB()) {
            vars[1].force(j + offSet, this);
        }
        for (int j : vars[1].getLB()) {
            vars[0].force(j - offSet, this);
        }
        // envelope
        for (int j : vars[0].getUB()) {
            if (!vars[1].getUB().contains(j + offSet)) {
                vars[0].remove(j, this);
            }
        }
        for (int j : vars[1].getUB()) {
            if (!vars[0].getUB().contains(j - offSet)) {
                vars[1].remove(j, this);
            }
        }
        sdm[0].unfreeze();
        sdm[1].unfreeze();
    }

    @Override
    public void propagate(int v, int mask) throws ContradictionException {
        sdm[v].freeze();
        if (v == 0) {
            tmp = offSet;
            tmpSet = vars[1];
        } else {
            tmp = -offSet;
            tmpSet = vars[0];
        }
        sdm[v].forEach(forced, SetEventType.ADD_TO_KER);
        sdm[v].forEach(removed, SetEventType.REMOVE_FROM_ENVELOPE);
        sdm[v].unfreeze();
    }

    @Override
    public ESat isEntailed() {
        for (int j : vars[0].getLB()) {
            if (!vars[1].getUB().contains(j + offSet)) {
                return ESat.FALSE;
            }
        }
        for (int j : vars[1].getLB()) {
            if (!vars[0].getUB().contains(j - offSet)) {
                return ESat.FALSE;
            }
        }
        if (isCompletelyInstantiated()) {
            return ESat.TRUE;
        }
        return ESat.UNDEFINED;
    }

}