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==extends QXmlDefaultHandler==

<source lang="cpp">

Foundations of Qt Development\Chapter08\xmlsaxread\main.cpp
/*
* Copyright (c) 2006-2007, Johan Thelin
*
* All rights reserved.
*
* 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 APress 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.
*
*/
#include <QFile>
#include <QXmlInputSource>
#include <QXmlSimpleReader>
#include <QXmlDefaultHandler>
#include <QtDebug>
class MyHandler : public QXmlDefaultHandler
{
public:
bool startDocument();
bool endDocument();

bool startElement( const QString &namespaceURI, const QString &localName, const QString &qName, const QXmlAttributes &atts );
bool endElement( const QString &namespaceURI, const QString &localName, const QString &qName );

bool characters( const QString &ch );
};
bool MyHandler::startDocument()
{
qDebug() << "Start of the document.";
return true;
}
bool MyHandler::endDocument()
{
qDebug() << "End of the document.";
return true;
}
bool MyHandler::startElement( const QString &namespaceURI, const QString &localName,
const QString &qName, const QXmlAttributes &atts )
{
qDebug() << "Start of element" << qName;
for( int i=0; i<atts.length(); ++i )
qDebug() << " " << atts.qName(i) << "=" << atts.value(i);
return true;
}
bool MyHandler::endElement( const QString &namespaceURI, const QString &localName,
const QString &qName )
{
qDebug() << "End of element" << qName;
return true;
}
bool MyHandler::characters( const QString &ch )
{
qDebug() << "Characters" << ch;
return true;
}
int main( int argc, char **argv )
{
QFile file( "simple.xml" );
if( !file.open( QIODevice::ReadOnly | QIODevice::Text ) )
{
qDebug( "Failed to open file for reading." );
return 0;
}
QXmlInputSource source( &file );

MyHandler handler;

QXmlSimpleReader reader;
reader.setContentHandler( &handler );
reader.parse( source );

file.close();

return 0;
}

</source>

==Simple parse==

<source lang="cpp">

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** 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
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** 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
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef HANDLER_H
#define HANDLER_H
#include <qstring.h>
#include <qxml.h>
class Handler : public QXmlDefaultHandler
{
public:
bool startDocument();
bool startElement(const QString &, const QString &, const QString &qName,
const QXmlAttributes &);
bool endElement(const QString &, const QString &, const QString &);
bool fatalError(const QXmlParseException &exception);
QStringList& names();
QList<int>& indentations();
private:
int indentationLevel;
QStringList elementName;
QList<int> elementIndentation;
};
#endif

/*
handler.cpp
Provides a handler for processing XML elements found by the reader.
The handler stores the names of elements it finds and their indentation
levels. The indentation level is initially set to zero.
When a starting element is found, the indentation level is increased;
when an ending element is found, the indentation level is decreased.
*/
#include <QDebug>
#include "handler.h"
/*!
Reset the state of the handler to ensure that new documents are
read correctly.
We return true to indicate that parsing should continue.
*/
bool Handler::startDocument()
{
elementName.clear();
elementIndentation.clear();
indentationLevel = 0;
return true;
}
/*!
Process each starting element in the XML document.
Append the element name to the list of elements found; add its
corresponding indentation level to the list of indentation levels.
Increase the level of indentation by one column.
We return true to indicate that parsing should continue.
*/
bool Handler::startElement(const QString &, const QString &,
const QString & qName, const QXmlAttributes &)
{
elementName.append(qName);
elementIndentation.append(indentationLevel);
indentationLevel += 1;
return true;
}
/*!
Process each ending element in the XML document.
Decrease the level of indentation by one column.
We return true to indicate that parsing should continue.
*/
bool Handler::endElement(const QString &, const QString &,
const QString &)
{
indentationLevel -= 1;
return true;
}
/*!
Report a fatal parsing error, and return false to indicate to the reader
that parsing should stop.
*/
bool Handler::fatalError (const QXmlParseException & exception)
{
qWarning() << QString("Fatal error on line %1, column %2: %3").arg(
exception.lineNumber()).arg(exception.columnNumber()).arg(
exception.message());
return false;
}
/*!
Return the list of element names found.
*/
QStringList& Handler::names ()
{
return elementName;
}
/*!
Return the list of indentations used for each element found.
*/
QList<int>& Handler::indentations ()
{
return elementIndentation;
}

#include <qfile.h>
#include <qxml.h>
#include "handler.h"
#include <iostream>
int main(int argc, char **argv)
{
if (argc != 2) {
std::cout << "Usage: " << argv[0] << " <filename>" << std::endl;
return 1;
}
QFile *file = new QFile(argv[1]);

QXmlSimpleReader xmlReader;
QXmlInputSource *source = new QXmlInputSource(file);

Handler *handler = new Handler;
xmlReader.setContentHandler(handler);
xmlReader.setErrorHandler(handler);

bool ok = xmlReader.parse(source);
if (!ok)
std::cout << "Parsing failed." << std::endl;
else {
QStringList names = handler->names();
QList<int> indentations = handler->indentations();
int items = names.count();
for (int i = 0; i < items; ++i) {
for (int j = 0; j < indentations[i]; ++j)
std::cout << " ";
std::cout << names[i].toLocal8Bit().constData() << std::endl;
}
}
return 0;
}

</source>

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