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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the utils of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights.  These rights are described in the Nokia Qt LGPL
** Exception version 1.1, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#ifndef NFA_H
#define NFA_H

#include <QMap>
#include <QHash>
#include <QString>
#include <QVector>
#include <QDebug>
#include <QStack>
#include <QByteArray>

#include "global.h"

typedef QHash<InputType, int> TransitionMap;

struct State
{
    QString symbol;
    TransitionMap transitions;
};

inline QDataStream &operator<<(QDataStream &stream, const State &state)
{
    return stream << state.symbol << state.transitions;
}

inline QDataStream &operator>>(QDataStream &stream, State &state)
{
    return stream >> state.symbol >> state.transitions;
}

struct DFA : public QVector<State>
{
    void debug() const;
    DFA minimize() const;
};

class NFA
{
public:
    static NFA createSingleInputNFA(InputType input);
    static NFA createSymbolNFA(const QString &symbol);
    static NFA createAlternatingNFA(const NFA &a, const NFA &b);
    static NFA createConcatenatingNFA(const NFA &a, const NFA &b);
    static NFA createOptionalNFA(const NFA &a);

    // convenience
    static NFA createStringNFA(const QByteArray &str);
    static NFA createSetNFA(const QSet<InputType> &set);
    static NFA createZeroOrOneNFA(const NFA &a);
    static NFA applyQuantity(const NFA &a, int minOccurrences, int maxOccurrences);

    void setTerminationSymbol(const QString &symbol);
    
    DFA toDFA() const;

    inline bool isEmpty() const { return states.isEmpty(); }
    inline int stateCount() const { return states.count(); }

    void debug();

private:
    void initialize(int size);
    void addTransition(int from, InputType input, int to);
    void copyFrom(const NFA &other, int baseState);

    void initializeFromPair(const NFA &a, const NFA &b,
                            int *initialA, int *finalA,
                            int *initialB, int *finalB);

    QSet<int> epsilonClosure(const QSet<int> &initialClosure) const;

    inline void assertValidState(int state)
    { Q_UNUSED(state); Q_ASSERT(state >= 0); Q_ASSERT(state < states.count()); }
    
#if defined(AUTOTEST)
public:
#endif
    int initialState;
    int finalState;

    QVector<State> states;
};

#endif // NFA_H