Filter.h

// Filter.h -- The interface to the super class of all CSP filters.

/*
 * Copyright (C) 1997, 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.
 */

/*
 * NOTE: This is an interal header file.
 * You should not attempt to use it directly.
 */

// $Id: Filter_8h-source.html,v 1.1 2005/05/25 12:37:18 tudor Exp $

#ifndef _CSP_KERNEL_Filter_H
#define _CSP_KERNEL_Filter_H


CSP_NAMESPACE_BEGIN(csp);


class CSP_API Retraction;


class CSP_API Filter
{
  public:
    Filter(
        const wstring& fullName,
        const wstring& shortName,
        Problem& problem,
        Retraction& retraction) :
        m_fullName(fullName),
        m_shortName(shortName),
        m_problem(problem),
        m_retraction(retraction) {}

    virtual ~Filter() {}

    const wstring name() const {
        return m_fullName + L" (" + m_shortName + L")"; }

    const wstring& fullName() const { return m_fullName; }

    const wstring& shortName() const { return m_shortName; }

    const Problem& problem() const { return m_problem; }

    Problem& problem() { return m_problem; }

    const Retraction& retraction() const { return m_retraction; }

    Retraction& retraction() { return m_retraction; }

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

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

    void updateValueFailures(Domain& diffs);

    virtual bool restoresArcConsistency() const = 0;

    bool subProblemIsArcConsistent(bool debugging) const;

    virtual bool isDummy() const { return false; }

    virtual bool propagate(
        const vlist_type& uninstantiatedVariables,
        const vlist_type& modifiedVariables,
        const bool keepChanges = true) = 0;

    const hash_set<const Variable*>& prunedVariables() const
    {
        return m_prunedVariables;
    }

    virtual bool init(
        const vlist_type& /*uninstantiatedVariables*/,
        bool /*propagate*/ = true)
    {
        return true;
    }

    virtual void done() {}

    virtual void restrict(const vlist_type& /*variables*/) {}

    virtual void unrestrict() {}

    virtual wostream& print(wostream& wos) const
    {
        return wos << L"Filter: " << name() << endl;
    }

    friend CSP_API wostream& operator<<(wostream& wos, const Filter& filter)
    {
        return filter.print(wos);
    }

    static void saveState(const list<Variable*>& variables);

    static void restoreState(const list<Variable*>& variables);

    static void postponeState(const list<Variable*>& variables);

  private:
    const wstring m_fullName;

    const wstring m_shortName;

  protected:
    Problem& m_problem;

    Retraction& m_retraction;

    void clearPrunedVariables() { m_prunedVariables.clear(); }

  private:
    Filter(const Filter&);

    Filter& operator=(const Filter&);

    hash_set<const Variable*> m_prunedVariables;
};


CSP_NAMESPACE_END(csp);


#endif // _CSP_KERNEL_Filter_H

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