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# bencodeparser.cpp Example File
network/torrent/bencodeparser.cpp

        /****************************************************************************
        **
        ** Copyright (C) 2004-2005 Trolltech AS. All rights reserved.
        **
        ** This file is part of the documentation of the Qt Toolkit.
        **
        ** This file may be used under the terms of the GNU General Public
        ** License version 2.0 as published by the Free Software Foundation
        ** and appearing in the file LICENSE.GPL included in the packaging of
        ** this file.  Please review the following information to ensure GNU
        ** General Public Licensing requirements will be met:
        ** http://www.trolltech.com/products/qt/opensource.html
        **
        ** If you are unsure which license is appropriate for your use, please
        ** review the following information:
        ** http://www.trolltech.com/products/qt/licensing.html or contact the
        ** sales department at sales@trolltech.com.
        **
        ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        **
        ****************************************************************************/

        #include "bencodeparser.h"

        #include <QList>
        #include <QMetaType>

        BencodeParser::BencodeParser()
        {
        }

        bool BencodeParser::parse(const QByteArray &content)
        {
            if (content.isEmpty()) {
                errString = QString("No content");
                return false;
            }

            this->content = content;
            index = 0;
            infoStart = 0;
            infoLength = 0;
            return getDictionary(&dictionaryValue);
        }

        QString BencodeParser::errorString() const
        {
            return errString;
        }

        QMap<QByteArray, QVariant> BencodeParser::dictionary() const
        {
            return dictionaryValue;
        }

        QByteArray BencodeParser::infoSection() const
        {
            return content.mid(infoStart, infoLength);
        }

        bool BencodeParser::getByteString(QByteArray *byteString)
        {
            const int contentSize = content.size();
            int size = -1;
            do {
                char c = content.at(index);
                if (c < '0' || c > '9') {
                    if (size == -1)
                        return false;
                    if (c != ':') {
                        errString = QString("Unexpected character at pos %1: %2")
                            .arg(index).arg(c);
                        return false;
                    }
                    ++index;
                    break;
                }
                if (size == -1)
                    size = 0;
                size *= 10;
                size += c - '0';
            } while (++index < contentSize);

            if (byteString)
                *byteString = content.mid(index, size);
            index += size;
            return true;
        }

        bool BencodeParser::getInteger(qint64 *integer)
        {
            const int contentSize = content.size();
            if (content.at(index) != 'i')
                return false;

            ++index;
            qint64 num = -1;
            bool negative = false;

            do {
                char c = content.at(index);
                if (c < '0' || c > '9') {
                    if (num == -1) {
                        if (c != '-' || negative)
                            return false;
                        negative = true;
                        continue;
                    } else {
                        if (c != 'e') {
                            errString = QString("Unexpected character at pos %1: %2")
                                .arg(index).arg(c);
                            return false;
                        }
                        ++index;
                        break;
                    }
                }
                if (num == -1)
                    num = 0;
                num *= 10;
                num += c - '0';
            } while (++index < contentSize);

            if (integer)
                *integer = negative ? -num : num;
            return true;
        }

        bool BencodeParser::getList(QList<QVariant> *list)
        {
            const int contentSize = content.size();
            if (content.at(index) != 'l')
                return false;

            QList<QVariant> tmp;
            ++index;

            do {
                if (content.at(index) == 'e') {
                    ++index;
                    break;
                }

                qint64 number;
                QByteArray byteString;
                QList<QVariant> tmpList;
                QMap<QByteArray, QVariant> dictionary;

                if (getInteger(&number))
                    tmp << number;
                else if (getByteString(&byteString))
                    tmp << byteString;
                else if (getList(&tmpList))
                    tmp << tmpList;
                else if (getDictionary(&dictionary))
                    tmp << qVariantFromValue<QMap<QByteArray, QVariant> >(dictionary);
                else {
                    errString = QString("error at index %1").arg(index);
                    return false;
                }
            } while (index < contentSize);

            if (list)
                *list = tmp;
            return true;
        }

        bool BencodeParser::getDictionary(QMap<QByteArray, QVariant> *dictionary)
        {
            const int contentSize = content.size();
            if (content.at(index) != 'd')
                return false;

            QMap<QByteArray, QVariant> tmp;
            ++index;

            do {
                if (content.at(index) == 'e') {
                    ++index;
                    break;
                }

                QByteArray key;
                if (!getByteString(&key))
                    break;

                if (key == "info")
                  infoStart = index;

                qint64 number;
                QByteArray byteString;
                QList<QVariant> tmpList;
                QMap<QByteArray, QVariant> dictionary;

                if (getInteger(&number))
                    tmp.insert(key, number);
                else if (getByteString(&byteString))
                    tmp.insert(key, byteString);
                else if (getList(&tmpList))
                    tmp.insert(key, tmpList);
                else if (getDictionary(&dictionary))
                    tmp.insert(key, qVariantFromValue<QMap<QByteArray, QVariant> >(dictionary));
                else {
                    errString = QString("error at index %1").arg(index);
                    return false;
                }

                if (key == "info")
                  infoLength = index - infoStart;

            } while (index < contentSize);

            if (dictionary)
                *dictionary = tmp;
            return true;
        }