/****************************************************************************+
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**+
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** All rights reserved.+
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** Contact: Nokia Corporation (qt-info@nokia.com)+
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**+
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** This file is part of the examples of the Qt Toolkit.+
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**+
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** $QT_BEGIN_LICENSE:LGPL$+
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** No Commercial Usage+
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** This file contains pre-release code and may not be distributed.+
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** You may use this file in accordance with the terms and conditions+
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** contained in the Technology Preview License Agreement accompanying+
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** this package.+
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**+
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** GNU Lesser General Public License Usage+
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** Alternatively, this file may be used under the terms of the GNU Lesser+
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** General Public License version 2.1 as published by the Free Software+
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** Foundation and appearing in the file LICENSE.LGPL included in the+
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** packaging of this file.  Please review the following information to+
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** ensure the GNU Lesser General Public License version 2.1 requirements+
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.+
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**+
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** In addition, as a special exception, Nokia gives you certain additional+
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** rights.  These rights are described in the Nokia Qt LGPL Exception+
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.+
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**+
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** If you have questions regarding the use of this file, please contact+
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** Nokia at qt-info@nokia.com.+
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**+
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**+
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**+
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**+
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** $QT_END_LICENSE$+
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**+
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****************************************************************************/+
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#include "randomlistmodel.h"+
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#include <stdlib.h>+
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+
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static const int bufferSize(500);+
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static const int lookAhead(100);+
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static const int halfLookAhead(lookAhead/2);+
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+
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RandomListModel::RandomListModel(QObject *parent)+
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: QAbstractListModel(parent), m_rows(bufferSize), m_count(10000)+
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{+
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}+
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+
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RandomListModel::~RandomListModel()+
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{+
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}+
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+
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int RandomListModel::rowCount(const QModelIndex &) const+
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{+
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    return m_count;+
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}+
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+
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//! [0]+
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QVariant RandomListModel::data(const QModelIndex &index, int role) const+
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{+
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    if (role != Qt::DisplayRole)+
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        return QVariant();+
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+
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    int row = index.row();+
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+
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    if (row > m_rows.lastIndex()) {+
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        if (row - m_rows.lastIndex() > lookAhead)+
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            cacheRows(row-halfLookAhead, qMin(m_count, row+halfLookAhead));+
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        else while (row > m_rows.lastIndex())+
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            m_rows.append(fetchRow(m_rows.lastIndex()+1));+
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    } else if (row < m_rows.firstIndex()) {+
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        if (m_rows.firstIndex() - row > lookAhead)+
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            cacheRows(qMax(0, row-halfLookAhead), row+halfLookAhead);+
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        else while (row < m_rows.firstIndex())+
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            m_rows.prepend(fetchRow(m_rows.firstIndex()-1));+
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    }+
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+
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    return m_rows.at(row);+
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}+
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+
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void RandomListModel::cacheRows(int from, int to) const+
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{+
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    for (int i = from; i <= to; ++i)+
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        m_rows.insert(i, fetchRow(i));+
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}+
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//![0]+
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+
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//![1]+
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QString RandomListModel::fetchRow(int position) const+
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{+
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    return QString::number(rand() % ++position);+
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}+
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//![1]+
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