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# bencodeparser.cpp Example File

network/torrent/bencodeparser.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
     ** You may use this file under the terms of the BSD license as follows:
     **
     ** "Redistribution and use in source and binary forms, with or without
     ** modification, are permitted provided that the following conditions are
     ** met:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
     **   * Redistributions in binary form must reproduce the above copyright
     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
     **   * Neither the name of The Qt Company Ltd nor the names of its
     **     contributors may be used to endorse or promote products derived
     **     from this software without specific prior written permission.
     **
     **
     ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
     **
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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 << QVariant::fromValue<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, QVariant::fromValue<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;
     }