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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.binary.element;

import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.constraints.PropagatorPriority;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.explanations.RuleStore;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.events.IEventType;
import org.chocosolver.util.ESat;
import org.chocosolver.util.objects.setDataStructures.iterable.IntIterableBitSet;
import org.chocosolver.util.tools.ArrayUtils;

/**
 * VALUE = TABLE[INDEX-OFFSET], ensuring arc consistency on result and index.
 * 

 *
 * @author Hadrien Cambazard
 * @author Fabien Hermenier
 * @author Charles Prud'homme
 * @author Jean-Guillaume Fages
 * @since 02/02/12
 */
//2015OCT - cprudhom : simplify the code, without changing the consistency, no Sort anymore
//2016AUG - jg : move filtering from bound/range to AC (add member reasoning)
public class PropElement extends Propagator {

    /**
     * Table of values
     */
    private final int[] values;

    /**
     * To match indices in {@link #values} and {@link #index}
     */
    private final int offset;

    /**
     * Index variable
     */
    private final IntVar index;

    /**
     * Resulting variable
     */
    private final IntVar result;

    /**
     * Set of forbidden indices and possible values
     */
    private final IntIterableBitSet fidx, pVals;

    /**
     * Create a propagator which ensures that VALUE = TABLE[INDEX-OFFSET] holds.
     * @param value integer variable
     * @param values array of ints
     * @param index integer variable
     * @param offset int
     */
    public PropElement(IntVar value, int[] values, IntVar index, int offset) {
        super(ArrayUtils.toArray(value, index), PropagatorPriority.BINARY, false);
        this.values = values;
        this.offset = offset;
        this.index = index;
        this.result = value;
        fidx = new IntIterableBitSet();
        fidx.setOffset(index.getLB());
        pVals = new IntIterableBitSet();
        pVals.setOffset(result.getLB());
    }

    @Override
    public void propagate(int evtmask) throws ContradictionException {
		index.updateBounds(offset, values.length - 1 + offset, this);
		fidx.clear();
		pVals.clear();
		int iub = index.getUB();
		for (int i = index.getLB(); i <= iub; i = index.nextValue(i)) {
			int value = values[i - offset];
			if (result.contains(value)){
				pVals.add(value);
			}else{
				fidx.add(i);
			}
		}
		result.removeAllValuesBut(pVals,this);
		if (!fidx.isEmpty()) {
			index.removeValues(fidx, this);
		}
		if (result.isInstantiated() && index.hasEnumeratedDomain() && !index.isInstantiated()) {
			setPassive();
		}
	}

    @Override
    public ESat isEntailed() {
        if (index.getUB() < offset || index.getLB() >= offset + values.length) {
            return ESat.FALSE;
        }
        if (isCompletelyInstantiated()) {
            return ESat.eval(result.contains(values[index.getValue() - offset]));
        } else if(result.isInstantiated()){
            int val = result.getValue();
            boolean foundVal = false;
            boolean foundOther = false;
            for(int i:index){
                if(i>=offset && i=offset && i 5) sb.append("..., ");
        sb.append(this.values[values.length - 1]);
        sb.append("> [").append(this.index).append("])");
        return sb.toString();
    }

    @Override
    public boolean why(RuleStore ruleStore, IntVar var, IEventType evt, int value) {
        return ruleStore.addPropagatorActivationRule(this)
                | ruleStore.addFullDomainRule((var == result) ? index : result);
    }

}