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A graph module for Choco Solver.
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/**
 *  Copyright (c) 1999-2014, 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:
 *
 *      * Redistributions of source code must retain the above copyright
 *        notice, this list of conditions and the following disclaimer.
 *      * 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.
 *      * Neither the name of the Ecole des Mines de Nantes 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 THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS AND CONTRIBUTORS 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.graphsolver.variables.delta;

import org.chocosolver.graphsolver.variables.GraphEventType;
import org.chocosolver.solver.ICause;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.search.loop.TimeStampedObject;
import org.chocosolver.solver.variables.delta.IDeltaMonitor;
import org.chocosolver.util.procedure.IntProcedure;
import org.chocosolver.util.procedure.PairProcedure;

/**
 * 

 *
 * @author Charles Prud'homme
 * @since 07/12/11
 */
public class GraphDeltaMonitor extends TimeStampedObject implements IDeltaMonitor {

    private final GraphDelta delta;
    private int[] first, last; // references, in variable delta value to propagate, to un propagated values
    private int[] frozenFirst, frozenLast; // same as previous while the recorder is frozen, to allow "concurrent modifications"
    private ICause propagator;

    public GraphDeltaMonitor(GraphDelta delta, ICause propagator) {
		super(delta.getEnvironment());
        this.delta = delta;
        this.first = new int[4];
        this.last = new int[4];
        this.frozenFirst = new int[4];
        this.frozenLast = new int[4];
        this.propagator = propagator;
    }

    @Override
    public void freeze() {
		if (needReset()) {
			for (int i = 0; i < 4; i++) {
				first[i] = last[i] = 0;
			}
			resetStamp();
		}
        for (int i = 0; i < 3; i++) {
            frozenFirst[i] = first[i]; // freeze indices
            first[i] = frozenLast[i] = last[i] = delta.getSize(i);
        }
        frozenFirst[3] = first[3]; // freeze indices
        first[3] = frozenLast[3] = last[3] = delta.getSize(GraphDelta.AE_tail);
    }

    @Override
    public void unfreeze() {
        delta.lazyClear();    // fix 27/07/12
        resetStamp();
        for (int i = 0; i < 3; i++) {
            first[i] = last[i] = delta.getSize(i);
        }
        first[3] = last[3] = delta.getSize(GraphDelta.AE_tail);
    }

    /**
     * Applies proc to every vertex which has just been removed or enforced, depending on evt.
     * @param proc    an incremental procedure over vertices
     * @param evt    either ENFORCENODE or REMOVENODE
     * @throws ContradictionException if a failure occurs
     */
    public void forEachNode(IntProcedure proc, GraphEventType evt) throws ContradictionException {
        int type;
        if (evt == GraphEventType.REMOVE_NODE) {
            type = GraphDelta.NR;
            for (int i = frozenFirst[type]; i < frozenLast[type]; i++) {
                if (delta.getCause(i, type) != propagator) {
                    proc.execute(delta.get(i, type));
                }
            }
        } else if (evt == GraphEventType.ADD_NODE) {
            type = GraphDelta.NE;
            for (int i = frozenFirst[type]; i < frozenLast[type]; i++) {
                if (delta.getCause(i, type) != propagator) {
                    proc.execute(delta.get(i, type));
                }
            }
        } else {
            throw new UnsupportedOperationException();
        }
    }

    /**
     * Applies proc to every arc which has just been removed or enforced, depending on evt.
     * @param proc    an incremental procedure over arcs
     * @param evt    either ENFORCEARC or REMOVEARC
     * @throws ContradictionException if a failure occurs
     */
    public void forEachArc(PairProcedure proc, GraphEventType evt) throws ContradictionException {
        if (evt == GraphEventType.REMOVE_ARC) {
            for (int i = frozenFirst[2]; i < frozenLast[2]; i++) {
                if (delta.getCause(i, GraphDelta.AR_tail) != propagator) {
                    proc.execute(delta.get(i, GraphDelta.AR_tail), delta.get(i, GraphDelta.AR_head));
                }
            }
        } else if (evt == GraphEventType.ADD_ARC) {
            for (int i = frozenFirst[3]; i < frozenLast[3]; i++) {
                if (delta.getCause(i, GraphDelta.AE_tail) != propagator) {
                    proc.execute(delta.get(i, GraphDelta.AE_tail), delta.get(i, GraphDelta.AE_head));
                }
            }
        } else {
            throw new UnsupportedOperationException();
        }
    }
}