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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.nary.alldifferent;

import org.chocosolver.solver.constraints.Constraint;
import org.chocosolver.solver.constraints.Propagator;
import org.chocosolver.solver.constraints.binary.PropNotEqualX_Y;
import org.chocosolver.solver.variables.IntVar;

/**
 * Ensures that all variables from VARS take a different value.
 * The consistency level should be chosen among "AC", "BC", "FC" and "DEFAULT".
 */
public class AllDifferent extends Constraint {

    public static final String AC= "AC";
    public static final String BC= "BC";
    public static final String FC= "FC";
    public static final String NEQS= "NEQS";
    public static final String DEFAULT= "DEFAULT";

    public AllDifferent(IntVar[] vars, String type) {
        super("AllDifferent", createPropagators(vars, type));
    }

    private static Propagator[] createPropagators(IntVar[] VARS, String consistency) {
        switch (consistency) {
            case NEQS: {
                int s = VARS.length;
                int k = 0;
                Propagator[] props = new Propagator[(s * s - s) / 2];
                for (int i = 0; i < s - 1; i++) {
                    for (int j = i + 1; j < s; j++) {
                        props[k++] = new PropNotEqualX_Y(VARS[i], VARS[j]);
                    }
                }
                return props;
            }
            case FC:
                return new Propagator[]{new PropAllDiffInst(VARS)};
            case BC:
                return new Propagator[]{new PropAllDiffInst(VARS), new PropAllDiffBC(VARS)};
            case AC:
                return new Propagator[]{new PropAllDiffInst(VARS), new PropAllDiffAC(VARS)};
            case DEFAULT:
            default: {
                // adds a Probabilistic AC (only if at least some variables have an enumerated domain)
                boolean enumDom = false;
                for (int i = 0; i < VARS.length && !enumDom; i++) {
                    if (VARS[i].hasEnumeratedDomain()) {
                        enumDom = true;
                    }
                }
                if (enumDom) {
                    return new Propagator[]{new PropAllDiffInst(VARS), new PropAllDiffBC(VARS), new PropAllDiffAdaptative(VARS)};
                } else {
                    return createPropagators(VARS, "BC");
                }
            }
        }
    }
}