CBJ.h

// CBJ.h -- The `conflict-directed back jumping' retraction interface.

/*
 * Copyright (C) 1998 Tudor Hulubei <tudor@hulubei.net>.
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2, or (at
 * your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA,
 * 02111-1307, USA.
 */

// $Id: CBJ_8h-source.html,v 1.1 2005/05/25 12:37:18 tudor Exp $

#ifndef _CSP_RETRACTIONS_CBJ_H
#define _CSP_RETRACTIONS_CBJ_H


CSP_NAMESPACE_BEGIN(csp);
CSP_NAMESPACE_BEGIN(retractions);


class CSP_API CBJ :
    public Retraction
{
  public:
    CBJ(Problem& problem) :
        Retraction(L"Conflict Directed Backjumping", problem),
        m_success(true) {}
    virtual ~CBJ() {}

    virtual void init() { m_gcs.clear(); m_jumps.clear(); }
    virtual void done() { m_gcs.clear(); }
    virtual void start();
    virtual void stop();

    virtual void recordDomainChange(
        Variable& victim,
        Variable& aggressor);

    virtual void recordFailure(
        Constraint& constraint,
        Variable& victim,
        Variable& aggressor);

    virtual int computeJump(bool chronological = true) const;

    virtual void unifyConflictSets(int jumpDepth);

    virtual void eraseConflictSets(int jumpDepth);

    virtual wostream& print(wostream& wos) const;

  private:
    // This is how we represent a conflict set.
    typedef set<const Variable*, id_less<const Variable*> > cs_type;

    /* This is set to `false' if recordDomainFailure() gets called
       (i.e. the filter failed).  Otherwise it is `true'.  */
    bool m_success;

    // The global conflict sets (each variable has one).
    hash_map<id_t, cs_type> m_gcs;

    // The local conflict sets (each variable has one).
    hash_map<id_t, cs_type> m_lcs;

    // Used as a temp object for unions, for optimization.
    cs_type m_ucs;

    /* Keep track of the number of x-levels jumps, for reporting
       purposes.  */
    mutable vector<int> m_jumps;

    void unify(const Variable& src, const Variable& dest);

    void updateStatistics(int currentDepth, int jumpDepth) const;
};


CSP_NAMESPACE_END(retractions);
CSP_NAMESPACE_END(csp);


#endif // _CSP_RETRACTIONS_CBJ_H

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