path: root/doc/man/man3/qxmlcontenthandler.3qt

'\" t
.TH QXmlContentHandler 3qt "2 February 2007" "Trolltech AS" \" -*- nroff -*-
.\" Copyright 1992-2007 Trolltech ASA.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QXmlContentHandler \- Interface to report the logical content of XML data
.SH SYNOPSIS
All the functions in this class are reentrant when Qt is built with thread support.</p>
.PP
\fC#include <qxml.h>\fR
.PP
Inherited by QXmlDefaultHandler.
.PP
.SS "Public Members"
.in +1c
.ti -1c
.BI "virtual void \fBsetDocumentLocator\fR ( QXmlLocator * locator ) = 0"
.br
.ti -1c
.BI "virtual bool \fBstartDocument\fR () = 0"
.br
.ti -1c
.BI "virtual bool \fBendDocument\fR () = 0"
.br
.ti -1c
.BI "virtual bool \fBstartPrefixMapping\fR ( const QString & prefix, const QString & uri ) = 0"
.br
.ti -1c
.BI "virtual bool \fBendPrefixMapping\fR ( const QString & prefix ) = 0"
.br
.ti -1c
.BI "virtual bool \fBstartElement\fR ( const QString & namespaceURI, const QString & localName, const QString & qName, const QXmlAttributes & atts ) = 0"
.br
.ti -1c
.BI "virtual bool \fBendElement\fR ( const QString & namespaceURI, const QString & localName, const QString & qName ) = 0"
.br
.ti -1c
.BI "virtual bool \fBcharacters\fR ( const QString & ch ) = 0"
.br
.ti -1c
.BI "virtual bool \fBignorableWhitespace\fR ( const QString & ch ) = 0"
.br
.ti -1c
.BI "virtual bool \fBprocessingInstruction\fR ( const QString & target, const QString & data ) = 0"
.br
.ti -1c
.BI "virtual bool \fBskippedEntity\fR ( const QString & name ) = 0"
.br
.ti -1c
.BI "virtual QString \fBerrorString\fR () = 0"
.br
.in -1c
.SH DESCRIPTION
The QXmlContentHandler class provides an interface to report the logical content of XML data.
.PP
If the application needs to be informed of basic parsing events, it can implement this interface and activate it using QXmlReader::setContentHandler(). The reader can then report basic document-related events like the start and end of elements and character data through this interface.
.PP
The order of events in this interface is very important, and mirrors the order of information in the document itself. For example, all of an element's content (character data, processing instructions, and sub-elements) appears, in order, between the startElement() event and the corresponding endElement() event.
.PP
The class QXmlDefaultHandler provides a default implementation for this interface; subclassing from the QXmlDefaultHandler class is very convenient if you only want to be informed of some parsing events.
.PP
The startDocument() function is called at the start of the document, and endDocument() is called at the end. Before parsing begins setDocumentLocator() is called. For each element startElement() is called, with endElement() being called at the end of each element. The characters() function is called with chunks of character data; ignorableWhitespace() is called with chunks of whitespace and processingInstruction() is called with processing instructions. If an entity is skipped skippedEntity() is called. At the beginning of prefix-URI scopes startPrefixMapping() is called.
.PP
See also the Introduction to SAX2.
.PP
See also QXmlDTDHandler, QXmlDeclHandler, QXmlEntityResolver, QXmlErrorHandler, QXmlLexicalHandler, and XML.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "bool QXmlContentHandler::characters ( const QString & ch )\fC [pure virtual]\fR"
The reader calls this function when it has parsed a chunk of character data (either normal character data or character data inside a CDATA section; if you need to distinguish between those two types you must use QXmlLexicalHandler::startCDATA() and QXmlLexicalHandler::endCDATA()). The character data is reported in \fIch\fR.
.PP
Some readers report whitespace in element content using the ignorableWhitespace() function rather than using this one.
.PP
A reader may report the character data of an element in more than one chunk; e.g. a reader might want to report "a<b" in three characters() events ("a ", "<" and " b").
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.SH "bool QXmlContentHandler::endDocument ()\fC [pure virtual]\fR"
The reader calls this function after it has finished parsing. It is called just once, and is the last handler function called. It is called after the reader has read all input or has abandoned parsing because of a fatal error.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.PP
See also startDocument().
.SH "bool QXmlContentHandler::endElement ( const QString & namespaceURI, const QString & localName, const QString & qName )\fC [pure virtual]\fR"
The reader calls this function when it has parsed an end element tag with the qualified name \fIqName\fR, the local name \fIlocalName\fR and the namespace URI \fInamespaceURI\fR.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.PP
See also the namespace description.
.PP
See also startElement().
.PP
Example: xml/tagreader/structureparser.cpp.
.SH "bool QXmlContentHandler::endPrefixMapping ( const QString & prefix )\fC [pure virtual]\fR"
The reader calls this function to signal the end of a prefix mapping for the prefix \fIprefix\fR.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.PP
See also the namespace description.
.PP
See also startPrefixMapping().
.SH "QString QXmlContentHandler::errorString ()\fC [pure virtual]\fR"
The reader calls this function to get an error string, e.g. if any of the handler functions returns FALSE.
.SH "bool QXmlContentHandler::ignorableWhitespace ( const QString & ch )\fC [pure virtual]\fR"
Some readers may use this function to report each chunk of whitespace in element content. The whitespace is reported in \fIch\fR.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.SH "bool QXmlContentHandler::processingInstruction ( const QString & target, const QString & data )\fC [pure virtual]\fR"
The reader calls this function when it has parsed a processing instruction.
.PP
\fItarget\fR is the target name of the processing instruction and \fIdata\fR is the data in the processing instruction.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.SH "void QXmlContentHandler::setDocumentLocator ( QXmlLocator * locator )\fC [pure virtual]\fR"
The reader calls this function before it starts parsing the document. The argument \fIlocator\fR is a pointer to a QXmlLocator which allows the application to get the parsing position within the document.
.PP
Do not destroy the \fIlocator\fR; it is destroyed when the reader is destroyed. (Do not use the \fIlocator\fR after the reader is destroyed).
.SH "bool QXmlContentHandler::skippedEntity ( const QString & name )\fC [pure virtual]\fR"
Some readers may skip entities if they have not seen the declarations (e.g. because they are in an external DTD). If they do so they report that they skipped the entity called \fIname\fR by calling this function.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.SH "bool QXmlContentHandler::startDocument ()\fC [pure virtual]\fR"
The reader calls this function when it starts parsing the document. The reader calls this function just once, after the call to setDocumentLocator(), and before any other functions in this class or in the QXmlDTDHandler class are called.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.PP
See also endDocument().
.PP
Example: xml/tagreader/structureparser.cpp.
.SH "bool QXmlContentHandler::startElement ( const QString & namespaceURI, const QString & localName, const QString & qName, const QXmlAttributes & atts )\fC [pure virtual]\fR"
The reader calls this function when it has parsed a start element tag.
.PP
There is a corresponding endElement() call when the corresponding end element tag is read. The startElement() and endElement() calls are always nested correctly. Empty element tags (e.g. \fC<x/>\fR) cause a startElement() call to be immediately followed by an endElement() call.
.PP
The attribute list provided only contains attributes with explicit values. The attribute list contains attributes used for namespace declaration (i.e. attributes starting with xmlns) only if the namespace-prefix property of the reader is TRUE.
.PP
The argument \fInamespaceURI\fR is the namespace URI, or QString::null if the element has no namespace URI or if no namespace processing is done. \fIlocalName\fR is the local name (without prefix), or QString::null if no namespace processing is done, \fIqName\fR is the qualified name (with prefix) and \fIatts\fR are the attributes attached to the element. If there are no attributes, \fIatts\fR is an empty attributes object.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.PP
See also the namespace description.
.PP
See also endElement().
.PP
Example: xml/tagreader/structureparser.cpp.
.SH "bool QXmlContentHandler::startPrefixMapping ( const QString & prefix, const QString & uri )\fC [pure virtual]\fR"
The reader calls this function to signal the begin of a prefix-URI namespace mapping scope. This information is not necessary for normal namespace processing since the reader automatically replaces prefixes for element and attribute names.
.PP
Note that startPrefixMapping() and endPrefixMapping() calls are not guaranteed to be properly nested relative to each other: all startPrefixMapping() events occur before the corresponding startElement() event, and all endPrefixMapping() events occur after the corresponding endElement() event, but their order is not otherwise guaranteed.
.PP
The argument \fIprefix\fR is the namespace prefix being declared and the argument \fIuri\fR is the namespace URI the prefix is mapped to.
.PP
If this function returns FALSE the reader stops parsing and reports an error. The reader uses the function errorString() to get the error message.
.PP
See also the namespace description.
.PP
See also endPrefixMapping().

.SH "SEE ALSO"
.BR http://doc.trolltech.com/qxmlcontenthandler.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports help us to help you. Thank you.
.P
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with
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users who prefer man pages, although this format is not officially
supported by Trolltech. 
.P
If you find errors in this manual page, please report them to
.BR qt-bugs@trolltech.com .
Please include the name of the manual page (qxmlcontenthandler.3qt) and the Qt
version (3.3.8).