Variable.h

// Variable.h -- The interface to the super class of all CSP
// variables.

/*
 * Copyright (C) 1997-1998, 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.
 */

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

// $Id: Variable_8h-source.html,v 1.1 2005/05/25 12:37:18 tudor Exp $

#ifndef _CSP_KERNEL_Variable_H
#define _CSP_KERNEL_Variable_H


CSP_NAMESPACE_BEGIN(csp);


class CSP_API Problem;
class CSP_API Constraint;


class CSP_API Variable
{
  public:
    typedef FastVector<Constraint*>::const_iterator constraint_iterator;

    Variable(const Problem& problem);

    virtual ~Variable();

    id_t id() const { return m_id; }

    virtual wstring name() const;

    virtual wstring color() const { return L"gray"; }

    virtual wstring textColor() const { return L"black"; }

    virtual wstring shape() const { return L"ellipse"; }

    void setId(id_t id) { m_id = id; }

    virtual void setBackdoorStatus(bool /*status*/) {}

    virtual void setBackdoorKeyStatus(bool /*status*/) {}

    virtual void setBranchingStatus(bool /*status*/) {}

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

    constraint_iterator add(Constraint& constraint)
    {
        return m_activeConstraints.insert(&constraint);
    }

    void remove(Constraint& constraint, bool recursive = false);

    size_t values() const { return m_domain.size(); }

    Value& value() const
    {
        assert(size_eq(m_domain, 1));
        return *m_domain.front();
    }

    Value& value(id_t id) const;

    Domain::iterator beginValues() { return m_domain.begin(); }

    Domain::iterator endValues() { return m_domain.end(); }

    Domain::const_iterator beginValues() const { return m_domain.begin(); }

    Domain::const_iterator endValues() const { return m_domain.end(); }

    constraint_iterator beginConstraints() const
    {
        return m_activeConstraints.begin();
    }

    constraint_iterator endConstraints() const
    {
        return m_activeConstraints.end();
    }

    constraint_iterator beginInactiveConstraints() const
    {
        return m_inactiveConstraints.begin();
    }

    constraint_iterator endInactiveConstraints() const
    {
        return m_inactiveConstraints.end();
    }

    Domain& domain() { return m_domain; }

    const Domain& domain() const { return m_domain; }

    size_t constraints() const { return m_activeConstraints.size(); }

    size_t inactiveConstraints() const { return m_inactiveConstraints.size(); }

    size_t hiddenConstraints() const;

    size_t degree() const { return constraints(); }

    ulonglong weightedDegree() const;

    void incrementDomainWipeouts() { m_domainWipeouts++; }

    ulonglong domainWipeouts() const { return m_domainWipeouts; }

    bool isPast() const { return m_past; }

    bool isCurrent() const { return m_current; }

    bool isFuture() const { return m_future; }

    bool isInstantiated() const { return m_iDepth != -1; }

    int instantiationDepth() const { return m_iDepth; }

    const vector<Domain*>& diffs() const { return m_savedDiffs; }

    void saveDiffs() { m_depth++; }

    void restoreDiffs();

    void postponeDiffs();

    void addDiffs(Domain& diffs);

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

    size_t prune(
        const Constraint& constraint,
        Domain& diffs,
        bool consistent = false);

    void sortDomain() { m_domain.sort(id_less<const Value*>()); }

    virtual wostream& print(wostream& wos) const;

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

  protected:
    void add(Value& v)
    {
        if (v.id() == NoId)
            v.setId(m_nextValueId++);

        m_domain.push_back(&v);
    }

    void remove(Value& v)
    {
        Domain::iterator i = find(m_domain.begin(), m_domain.end(), &v);
        assert(i != m_domain.end());
        assert(*i == &v);
        v.setId(NoId);
        m_domain.erase(i);
        m_nextValueId--;
    }

  private:
    Variable(const Variable&);

    Variable& operator=(const Variable&);

    void activateConstraint(const Constraint& constraint);

    void deactivateConstraint(const Constraint& constraint);

    void hideConstraint(const Constraint& constraint);

    void unhideConstraint(const Constraint& constraint);

    // These should only be called from `Decomposition'.  //

    friend class Decomposition;

    void setPastFlag(bool past) { m_past = past; }

    void setCurrentFlag(bool current) { m_current = current; }

    void setFutureFlag(bool future) { m_future = future; }

    void instantiate();

    void deinstantiate();

    void hideConstraints();

    void unhideConstraints(int depth);

    void getReachableVariables(vhash_type& reachableVariables) const;

    void createHidingDepth();

    int hidingDepth() const { return m_hiddenConstraints.size() - 1; }

    // These should only be called from `Problem'.  //

    friend class Problem;

    virtual void init()
    {
        m_past = false;
        m_current = false;
        m_future = true;
        m_domainWipeouts = 0;
    }

    virtual void done() {}

    bool isInternallyConsistent();

    id_t m_id;

    const Problem& m_problem;

    FastVector<Constraint*> m_activeConstraints;

    FastVector<Constraint*> m_inactiveConstraints;

    Domain m_domain;

    int m_depth;

    int m_iDepth;

    vector<int> m_savedDepths;

    vector<Domain*> m_savedDiffs;

    id_t m_nextValueId;

    bool m_past;

    bool m_current;

    bool m_future;

    vector<vector<Constraint*>*> m_hiddenConstraints;

    // FIXME: It wouldn't be a bad idea to store the following fields
    // in a separate data structure that is only allocated when these
    // fields are actually needed.  They're used by heuristics.

    ulonglong m_domainWipeouts;
};


CSP_NAMESPACE_END(csp);


#endif // _CSP_KERNEL_Variable_H

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