Degree.h

// Degree.h -- The `maximum/minimum degree' variable ordering
// heuristic interface.

/*
 * Copyright (C) 1998,2003,2004 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: Degree_8h-source.html,v 1.1 2005/05/25 12:37:18 tudor Exp $

#ifndef _CSP_HEURISTICS_VARIABLE_Degree_H
#define _CSP_HEURISTICS_VARIABLE_Degree_H


#include "../../caches/Degrees.h"


CSP_NAMESPACE_BEGIN(csp);
CSP_NAMESPACE_BEGIN(heuristics);
CSP_NAMESPACE_BEGIN(variables);


class DegreeLT :
    public StrictWeakVariableOrdering
{
  public:
    DegreeLT(caches::Degrees& degrees) : m_degrees(degrees) {}

    bool operator()(const Variable* variable0, const Variable* variable1)
    {
        return
            m_degrees.degree(*variable0) <
            m_degrees.degree(*variable1);
    }

  private:
    caches::Degrees& m_degrees;
};


class DegreeGT :
    public StrictWeakVariableOrdering
{
  public:
    DegreeGT(caches::Degrees& degrees) : m_degrees(degrees) {}

    bool operator()(const Variable* variable0, const Variable* variable1)
    {
        return
            m_degrees.degree(*variable0) >
            m_degrees.degree(*variable1);
    }

  private:
    caches::Degrees& m_degrees;
};


class DegreeEQ :
    public StrictWeakVariableOrdering
{
  public:
    DegreeEQ(caches::Degrees& degrees) :
        m_degrees(degrees),
        m_previousVariable0(0),
        m_previousVariable1(0),
        m_previousDegree0(0),
        m_previousDegree1(0) {}

    bool operator()(const Variable* variable0, const Variable* variable1);

    void reset()
    {
        m_previousVariable0 = 0;
        m_previousVariable1 = 0;
        m_previousDegree0 = 0;
        m_previousDegree1 = 0;
    }

  private:
    caches::Degrees& m_degrees;

    const Variable* m_previousVariable0;
    const Variable* m_previousVariable1;

    size_t m_previousDegree0;
    size_t m_previousDegree1;
};


class CSP_API Degree :
    public VariableOH
{
  public:
    enum Preference
    {
        Minimum,

        Maximum
    };

    Degree(
        Decomposition& decomposition,
        const vector<pair<double, double> >& intervals,
        double quality = 1,
        Preference preference = Maximum);

    virtual void select(vlist_type& selectable, vlist_type& selected);

  private:
    Degree(const Degree&);

    Degree& operator=(const Degree&);

    Preference m_preference;

    caches::Degrees m_degrees;

    DegreeLT m_compareLT;

    DegreeGT m_compareGT;

    DegreeEQ m_compareEQ;
};


CSP_NAMESPACE_END(variables);
CSP_NAMESPACE_END(heuristics);
CSP_NAMESPACE_END(csp);


#endif // _CSP_HEURISTICS_VARIABLE_Degree_H

// Local Variables:
// mode: C++
// End:

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