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| author | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-11-08 12:31:36 -0600 |
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| committer | Timothy Pearson <kb9vqf@pearsoncomputing.net> | 2011-11-08 12:31:36 -0600 |
| commit | d796c9dd933ab96ec83b9a634feedd5d32e1ba3f (patch) | |
| tree | 6e3dcca4f77e20ec8966c666aac7c35bd4704053 /doc/html/xml-sax-walkthrough.html | |
| download | tqt3-d796c9dd933ab96ec83b9a634feedd5d32e1ba3f.tar.gz tqt3-d796c9dd933ab96ec83b9a634feedd5d32e1ba3f.zip | |
Test conversion to TQt3 from Qt3 8c6fc1f8e35fd264dd01c582ca5e7549b32ab731
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diff --git a/doc/html/xml-sax-walkthrough.html b/doc/html/xml-sax-walkthrough.html new file mode 100644 index 000000000..d9a2e0c23 --- /dev/null +++ b/doc/html/xml-sax-walkthrough.html @@ -0,0 +1,220 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/xml-sax-walkthrough.doc:36 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>Walkthrough: How to use the TQt SAX2 classes</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td valign=center> + <a href="index.html"> +<font color="#004faf">Home</font></a> + | <a href="classes.html"> +<font color="#004faf">All Classes</font></a> + | <a href="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Walkthrough: How to use the TQt SAX2 classes</h1> + + +<p> +<p> For a general discussion of the XML topics in TQt please refer to +the document <a href="xml.html">XML Module.</a> +To learn more about SAX2 see the document describing +<a href="xml.html#sax2">the TQt SAX2 implementation.</a> +<p> Before reading on you should at least be familiar with +the <a href="xml.html#sax2Intro">Introduction to SAX2.</a> +<p> <a name="tquickStart"></a> +<h2>A tiny parser</h2> +<p> In this section we will present a small example reader that outputs +the names of all elements in an XML document on the command line. +The element names are indented corresponding to their nesting level. +<p> As mentioned in <a href="xml.html#sax2Intro">Introduction to SAX2</a> +we have to implement the functions of the handler classes that we are +interested in. In our case these are only three: +<a href="qxmlcontenthandler.html#startDocument">TQXmlContentHandler::startDocument</a>(), +<a href="qxmlcontenthandler.html#startElement">TQXmlContentHandler::startElement</a>() and +<a href="qxmlcontenthandler.html#endElement">TQXmlContentHandler::endElement</a>(). +<p> For this purpose we use a subclass of the <a href="qxmldefaulthandler.html">TQXmlDefaultHandler</a> (remember +that the special handler classes are all abstract and the default handler class +provides an implementation that does not change the parsing behavior): +<p> <pre>/**************************************************************************** +** $Id: qt/structureparser.h 3.3.8 edited Jan 11 14:37 $ +** +** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved. +** +** This file is part of an example program for TQt. This example +** program may be used, distributed and modified without limitation. +** +*****************************************************************************/ + +#ifndef STRUCTUREPARSER_H +#define STRUCTUREPARSER_H + +#include <<a href="qxml-h.html">qxml.h</a>> + +class TQString; + +class StructureParser : public <a href="qxmldefaulthandler.html">TQXmlDefaultHandler</a> +{ +public: + bool startDocument(); + bool startElement( const <a href="qstring.html">TQString</a>&, const <a href="qstring.html">TQString</a>&, const <a href="qstring.html">TQString</a>& , + const <a href="qxmlattributes.html">TQXmlAttributes</a>& ); + bool endElement( const <a href="qstring.html">TQString</a>&, const <a href="qstring.html">TQString</a>&, const <a href="qstring.html">TQString</a>& ); + +private: + <a href="qstring.html">TQString</a> indent; +}; + +#endif +</pre> + +<p> Apart from the private helper variable <em>indent</em> that we will use to +get indentation right, there is nothing special about our new +<em>StructureParser</em> class. +<p> + +<p> Even the implementation is straight-forward: +<p> <pre> #include "structureparser.h" + + #include <stdio.h> + #include <<a href="qstring-h.html">qstring.h</a>> +</pre> +<p> First we overload <a href="qxmlcontenthandler.html#startDocument">TQXmlContentHandler::startDocument</a>() with a non-empty version. +<p> <pre> <a name="x2137"></a>bool StructureParser::<a href="qxmlcontenthandler.html#startDocument">startDocument</a>() + { + indent = ""; + return TRUE; + } +</pre> +<p> At the beginning of the document we simply +set <em>indent</em> to an empty string because we +want to print out the root element without any indentation. +Also we return TRUE so that the parser continues without +reporting an error. +<p> Because we want to be informed when the parser comes +accross a start tag of an element and subsequently print it out, we +have to overload <a href="qxmlcontenthandler.html#startElement">TQXmlContentHandler::startElement</a>(). +<p> <pre> <a name="x2138"></a>bool StructureParser::<a href="qxmlcontenthandler.html#startElement">startElement</a>( const <a href="qstring.html">TQString</a>&, const <a href="qstring.html">TQString</a>&, + const <a href="qstring.html">TQString</a>& qName, + const <a href="qxmlattributes.html">TQXmlAttributes</a>& ) + { + printf( "%s%s\n", (const char*)indent, (const char*)qName ); + indent += " "; + return TRUE; + } +</pre> +<p> This is what the implementation does: The name of the element with +preceding indentation is printed out followed by a linebreak. +Strictly speaking <em>qName</em> contains the local element name +without an eventual prefix denoting the <a href="xml.html#namespaces">namespace.</a> +<p> If another element follows before the current element's end tag +it should be indented. Therefore we add four spaces to the +<em>indent</em> string. +<p> Finally we return TRUE in order to let the parser continue without +errors. +<p> The last functionality we need to add is the parser's behaviour when an +end tag occurs. This means overloading <a href="qxmlcontenthandler.html#endElement">TQXmlContentHandler::endElement</a>(). +<p> <pre> <a name="x2136"></a>bool StructureParser::<a href="qxmlcontenthandler.html#endElement">endElement</a>( const <a href="qstring.html">TQString</a>&, const <a href="qstring.html">TQString</a>&, const <a href="qstring.html">TQString</a>& ) + { + indent.remove( (uint)0, 4 ); + return TRUE; + } +</pre> +<p> Obviously we then should shorten the <em>indent</em> string by the four +whitespaces added in startElement(). +<p> With this we're done with our parser and can start writing the main() +program. +<p> + +<p> <pre> #include "structureparser.h" + #include <<a href="qfile-h.html">qfile.h</a>> + #include <<a href="qxml-h.html">qxml.h</a>> + #include <<a href="qwindowdefs-h.html">qwindowdefs.h</a>> + + int main( int argc, char **argv ) + { + if ( argc < 2 ) { + fprintf( stderr, "Usage: %s <xmlfile> [<xmlfile> ...]\n", argv[0] ); + return 1; + } +</pre> +<p> This check ensures that we have a sequence of files from the command +line to examine. +<p> <pre> StructureParser handler; +</pre> +<p> The next step is to create an instance of the <em>StructureParser</em>. +<p> <pre> <a href="qxmlsimplereader.html">TQXmlSimpleReader</a> reader; + <a name="x2140"></a> reader.<a href="qxmlreader.html#setContentHandler">setContentHandler</a>( &handler ); +</pre> +<p> After that we set up the reader. As our <em>StructureParser</em> +class deals with <a href="qxmlcontenthandler.html">TQXmlContentHandler</a> functionality only +we simply register it as the content handler of our choice. +<p> <pre> for ( int i=1; i < argc; i++ ) { +</pre> +<p> Successively we deal with all files given as command line arguments. +<p> <pre> <a href="qfile.html">TQFile</a> xmlFile( argv[i] ); + <a href="qxmlinputsource.html">TQXmlInputSource</a> source( &xmlFile ); +</pre> +<p> Then we create a +<a href="qxmlinputsource.html">TQXmlInputSource</a> for the XML file to be parsed. +<p> <pre> <a name="x2139"></a> reader.<a href="qxmlsimplereader.html#parse">parse</a>( source ); +</pre> +<p> Now we take our input source and start parsing. +<p> <pre> } + return 0; + } +</pre> +<p> Running the program on the following XML file... +<p> <pre><animals> +<mammals> + <monkeys> <gorilla/> <orangutan/> </monkeys> +</mammals> +<birds> <pigeon/> <penguin/> </birds> +</animals> + +</pre> + +<p> ... produces the following output: +<pre> +animals + mammals + monkeys + gorilla + orang-utan + birds + pigeon + penguin +</pre> + +<p> It will however refuse to produce the correct result if you e.g. insert +a whitespace between a < and the element name in your test-XML file. +To prevent such annoyances +you should always install an error handler with <a href="qxmlreader.html#setErrorHandler">TQXmlReader::setErrorHandler</a>(). This allows you to report +parsing errors to the user. +<p> <p>See also <a href="step-by-step-examples.html">Step-by-step Examples</a>. + +<!-- eof --> +<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>TQt 3.3.8</div> +</table></div></address></body> +</html> |