AC2001.h

// AC2001.h -- The AC-2001 filter interface.

/*
 * Copyright (C) 2004 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: AC2001_8h-source.html,v 1.1 2005/05/25 12:37:18 tudor Exp $

#ifndef _CSP_FILTERS_AC2001_H
#define _CSP_FILTERS_AC2001_H


CSP_NAMESPACE_BEGIN(csp);
CSP_NAMESPACE_BEGIN(filters);


class CSP_API AC2001 :
    public Filter
{
  public:
    AC2001(Problem& problem, Retraction& retraction) :
        Filter(L"Arc Consistency 2001", L"AC-2001", problem, retraction) {}
    ~AC2001() {}

    virtual bool init(
        const vlist_type& uninstantiatedVariables,
        bool propagate = true);
    virtual void done() { Filter::done(); }

    virtual bool restoresArcConsistency() const { return true; }

    virtual bool propagate(
        const vlist_type& uninstantiatedVariables,
        const vlist_type& modifiedVariables,
        const bool keepChanges = true);

  private:
    AC2001(const AC2001&);

    AC2001& operator=(const AC2001&);

    void insertInQueue(Variable& variable);

    void removeFromQueue(Variable& variable);

    bool isInQueue(const Variable& variable);

    void prune(
        Variable& variable,
        const Constraint& constraint,
        Domain& diffs);

    Value* findSupport(
        Variable& variable,
        Value& value,
        const Constraint& constraint,
        Variable& pair);

    Value* findSupportInDomain(
        Variable& variable,
        Value& value,
        const Constraint& constraint,
        Variable& pair,
        Domain& subDomain);

    void clearSupports();

    void clearDomains();

    Domain m_diffs;

    deque<Variable*> m_queue;

    hash_set<const Variable*> m_inQueue;

    typedef hash_map<const Value*, Value*> shash_type;
    typedef hash_map<const Constraint*, shash_type*> phash_type;
    typedef hash_map<const Variable*, phash_type*> thash_type;
    typedef hash_map<const Variable*, Domain*> dhash_type;

    thash_type m_supports;

    dhash_type m_domains;
};


CSP_NAMESPACE_END(filters);
CSP_NAMESPACE_END(csp);


#endif // _CSP_FILTERS_AC2001_H

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