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****************************************************************************/

#ifndef QGRAPH_P_H

#define QGRAPH_P_H

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists purely as an

// implementation detail.  This header file may change from version to

// version without notice, or even be removed.

//

// We mean it.

//

#include <QtCore/QHash>

#include <QtCore/QQueue>

#include <QtCore/QString>

#include <QtCore/QDebug>

#include <float.h>

QT_BEGIN_NAMESPACE

template <typename Vertex, typename EdgeData>

class Graph

{

public:

    Graph() {}

    class const_iterator {

    public:

        const_iterator(const Graph *graph, bool begin) : g(graph){

            if (begin) {

                row = g->m_graph.constBegin();

                //test if the graph is empty

                if (row != g->m_graph.constEnd())

                {

                    column = (*row)->constBegin();

                }

            } else {

                row = g->m_graph.constEnd();

            }

        }

        inline Vertex *operator*() {

            return column.key();

        }

        inline Vertex *from() const {

            return row.key();

        }

        inline Vertex *to() const {

            return column.key();

        }

        inline bool operator==(const const_iterator &o) const { return !(*this != o); }

        inline bool operator!=(const const_iterator &o) const {

           if (row ==  g->m_graph.end()) {

                return row != o.row;

           } else {

                return row != o.row || column != o.column;

           }

        }

        inline const_iterator& operator=(const const_iterator &o) const { row = o.row; column = o.column; return *this;}

        // prefix

        const_iterator &operator++() {

            if (row != g->m_graph.constEnd()) {

                ++column;

                if (column == (*row)->constEnd()) {

                    ++row;

                    if (row != g->m_graph.constEnd()) {

                        column = (*row)->constBegin();

                    }

                }

            }

            return *this;

        }

    private:

        const Graph *g;

        Q_TYPENAME QHash<Vertex *, QHash<Vertex *, EdgeData *> * >::const_iterator row;

        Q_TYPENAME QHash<Vertex *, EdgeData *>::const_iterator column;

    };

    const_iterator constBegin() const {

        return const_iterator(this,true);

    }

    const_iterator constEnd() const {

        return const_iterator(this,false);

    }

    /*!

     * \internal

     *

     * If there is an edge between \a first and \a second, it will return a structure

     * containing the data associated with the edge, otherwise it will return 0.

     *

     */

    EdgeData *edgeData(Vertex* first, Vertex* second) {

        QHash<Vertex *, EdgeData *> *row = m_graph.value(first);

        return row ? row->value(second) : 0;

    }

    void createEdge(Vertex *first, Vertex *second, EdgeData *data)

    {

        // Creates a bidirectional edge

#if defined(QT_DEBUG) && 0

        qDebug("Graph::createEdge(): %s",

               qPrintable(QString::fromAscii("%1-%2")

                          .arg(first->toString()).arg(second->toString())));

#endif

        if (edgeData(first, second)) {

#ifdef QT_DEBUG

            qWarning("%s-%s already has an edge", qPrintable(first->toString()), qPrintable(second->toString()));

#endif

        }

        createDirectedEdge(first, second, data);

        createDirectedEdge(second, first, data);

    }

    void removeEdge(Vertex *first, Vertex *second)

    {

        // Removes a bidirectional edge

#if defined(QT_DEBUG) && 0

        qDebug("Graph::removeEdge(): %s",

               qPrintable(QString::fromAscii("%1-%2")

                          .arg(first->toString()).arg(second->toString())));

#endif

        EdgeData *data = edgeData(first, second);

        removeDirectedEdge(first, second);

        removeDirectedEdge(second, first);

        if (data) delete data;

    }

    EdgeData *takeEdge(Vertex* first, Vertex* second)

    {

#if defined(QT_DEBUG) && 0

        qDebug("Graph::takeEdge(): %s",

               qPrintable(QString::fromAscii("%1-%2")

                          .arg(first->toString()).arg(second->toString())));

#endif

        // Removes a bidirectional edge

        EdgeData *data = edgeData(first, second);

        if (data) {

            removeDirectedEdge(first, second);

            removeDirectedEdge(second, first);

        }

        return data;

    }

    QList<Vertex *> adjacentVertices(Vertex *vertex) const

    {

        QHash<Vertex *, EdgeData *> *row = m_graph.value(vertex);

        QList<Vertex *> l;

        if (row)

            l = row->keys();

        return l;

    }

    QSet<Vertex*> vertices() const {

        QSet<Vertex *> setOfVertices;

        for (const_iterator it = constBegin(); it != constEnd(); ++it) {

            setOfVertices.insert(*it);

        }

        return setOfVertices;

    }

    QList<QPair<Vertex*, Vertex*> > connections() const {

        QList<QPair<Vertex*, Vertex*> > conns;

        for (const_iterator it = constBegin(); it != constEnd(); ++it) {

            Vertex *from = it.from();

            Vertex *to = it.to();

            // do not return (from,to) *and* (to,from)

            if (from < to) {

                conns.append(qMakePair(from, to));

            }

        }

        return conns;

    }

#if defined(QT_DEBUG)

    QString serializeToDot() {   // traversal

        QString strVertices;

        QString edges;

        QSet<Vertex *> setOfVertices = vertices();

        for (Q_TYPENAME QSet<Vertex*>::const_iterator it = setOfVertices.begin(); it != setOfVertices.end(); ++it) {

            Vertex *v = *it;

            QList<Vertex*> adjacents = adjacentVertices(v);

            for (int i = 0; i < adjacents.count(); ++i) {

                Vertex *v1 = adjacents.at(i);

                EdgeData *data = edgeData(v, v1);

                bool forward = data->from == v;

                if (forward) {

                        .arg(v->toString())

                        .arg(v1->toString())

                        .arg(data->minSize)

                        .arg(data->prefSize)

                        .arg(data->maxSize)

                        ;

                }

            }

        }

        return QString::fromAscii("%1\n%2\n").arg(strVertices).arg(edges);

    }

#endif

protected:

    void createDirectedEdge(Vertex *from, Vertex *to, EdgeData *data)

    {

        QHash<Vertex *, EdgeData *> *adjacentToFirst = m_graph.value(from);

        if (!adjacentToFirst) {

            adjacentToFirst = new QHash<Vertex *, EdgeData *>();

            m_graph.insert(from, adjacentToFirst);

        }

        adjacentToFirst->insert(to, data);

    }

    void removeDirectedEdge(Vertex *from, Vertex *to)

    {

        QHash<Vertex *, EdgeData *> *adjacentToFirst = m_graph.value(from);

        Q_ASSERT(adjacentToFirst);

        adjacentToFirst->remove(to);

        if (adjacentToFirst->isEmpty()) {

            //nobody point to 'from' so we can remove it from the graph

            m_graph.remove(from);

            delete adjacentToFirst;

        }

    }

private:

    QHash<Vertex *, QHash<Vertex *, EdgeData *> *> m_graph;

};

QT_END_NAMESPACE

#endif