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

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 ** This file is part of the examples of the Qt Toolkit.
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 ** 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
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 ** Alternatively, this file may be used under the terms of the GNU
 ** General Public License version 3.0 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
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 #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;
 }


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Qt 4.6.3