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Open-source constraint solver.
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/**
 * 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.extension.binary;

import org.chocosolver.solver.constraints.extension.Tuples;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.events.IntEventType;
import org.chocosolver.util.iterators.DisposableValueIterator;
import org.chocosolver.util.objects.setDataStructures.iterable.IntIterableBitSet;

/**
 * Forward checking algorithm for table constraint
 * 

 *
 * @author Charles Prud'homme, Hadrien Cambazard
 * @since 24/04/2014
 */
public class PropBinFC extends PropBinCSP {

    private final IntIterableBitSet vrms;

    public PropBinFC(IntVar x, IntVar y, Tuples tuples) {
        this(x, y, new CouplesTable(tuples, x, y));
    }

    private PropBinFC(IntVar x, IntVar y, CouplesTable table) {
        super(x, y, table);
        vrms = new IntIterableBitSet();
    }

    @Override
    public int getPropagationConditions(int vIdx) {
        return IntEventType.instantiation();
    }

    @Override
    public void propagate(int evtmask) throws ContradictionException {
        if (v0.isInstantiated())
            onInstantiation0();
        if (v1.isInstantiated())
            onInstantiation1();
    }

    @Override
    public void propagate(int idxVarInProp, int mask) throws ContradictionException {
        if (idxVarInProp == 0) onInstantiation0();
        else onInstantiation1();
    }

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

    private void onInstantiation0() throws ContradictionException {
        int value = v0.getValue();
        DisposableValueIterator values = v1.getValueIterator(true);
        vrms.clear();
        vrms.setOffset(v1.getLB());
        try {
            while (values.hasNext()) {
                int val = values.next();
                if (!relation.isConsistent(value, val)) {
                    vrms.add(val);
                }
            }
            v1.removeValues(vrms, this);
        } finally {
            values.dispose();
        }
    }

    private void onInstantiation1() throws ContradictionException {
        int value = v1.getValue();
        DisposableValueIterator values = v0.getValueIterator(true);
        vrms.clear();
        vrms.setOffset(v0.getLB());
        try {
            while (values.hasNext()) {
                int val = values.next();
                if (!relation.isConsistent(val, value)) {
                    vrms.add(val);
                }
            }
            v0.removeValues(vrms, this);
        } finally {
            values.dispose();
        }
    }
}