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QXmlSimpleReader Class Reference
[QtXml module]

The QXmlSimpleReader class provides an implementation of a simple XML parser. More...

Inherits QXmlReader.


Detailed Description

The QXmlSimpleReader class provides an implementation of a simple XML parser.

This XML reader is suitable for a wide range of applications. It is able to parse well-formed XML and can report the namespaces of elements to a content handler; however, it does not parse any external entities. For historical reasons, Attribute Value Normalization and End-of-Line Handling as described in the XML 1.0 specification is not performed.

The easiest pattern of use for this class is to create a reader instance, define an input source, specify the handlers to be used by the reader, and parse the data.

For example, we could use a QFile to supply the input. Here, we create a reader, and define an input source to be used by the reader:

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

A handler lets us perform actions when the reader encounters certain types of content, or if errors in the input are found. The reader must be told which handler to use for each type of event. For many common applications, we can create a custom handler by subclassing QXmlDefaultHandler, and use this to handle both error and content events:

     Handler *handler = new Handler;

If you don't set at least the content and error handlers, the parser will fall back on its default behavior---and will do nothing.

The most convenient way to handle the input is to read it in a single pass using the parse() function with an argument that specifies the input source:

     bool ok = xmlReader.parse(source);

     if (!ok)
         std.cout << "Parsing failed." << std.endl;

If you can't parse the entire input in one go (for example, it is huge, or is being delivered over a network connection), data can be fed to the parser in pieces. This is achieved by telling parse() to work incrementally, and making subsequent calls to the parseContinue() function, until all the data has been processed.

A common way to perform incremental parsing is to connect the readyRead() signal of a network reply a slot, and handle the incoming data there. See QNetworkAccessManager.

Aspects of the parsing behavior can be adapted using setFeature() and setProperty().

 xmlReader.setFeature("http://xml.org/sax/features/namespace-prefixes", true);

QXmlSimpleReader is not reentrant. If you want to use the class in threaded code, lock the code using QXmlSimpleReader with a locking mechanism, such as a QMutex.

Method Documentation

QXmlSimpleReader.__init__ (self)

Constructs a simple XML reader.

QXmlContentHandler QXmlSimpleReader.contentHandler (self)

Reimplemented from QXmlReader.contentHandler().

See also setContentHandler().

QXmlDeclHandler QXmlSimpleReader.declHandler (self)

Reimplemented from QXmlReader.declHandler().

See also setDeclHandler().

QXmlDTDHandler QXmlSimpleReader.DTDHandler (self)

Reimplemented from QXmlReader.DTDHandler().

See also setDTDHandler().

QXmlEntityResolver QXmlSimpleReader.entityResolver (self)

Reimplemented from QXmlReader.entityResolver().

See also setEntityResolver().

QXmlErrorHandler QXmlSimpleReader.errorHandler (self)

Reimplemented from QXmlReader.errorHandler().

See also setErrorHandler().

(bool, bool ok) QXmlSimpleReader.feature (self, QString name)

Reimplemented from QXmlReader.feature().

See also setFeature().

bool QXmlSimpleReader.hasFeature (self, QString name)

Reimplemented from QXmlReader.hasFeature().

bool QXmlSimpleReader.hasProperty (self, QString name)

Reimplemented from QXmlReader.hasProperty().

QXmlLexicalHandler QXmlSimpleReader.lexicalHandler (self)

Reimplemented from QXmlReader.lexicalHandler().

See also setLexicalHandler().

bool QXmlSimpleReader.parse (self, QXmlInputSource input)

Reimplemented from QXmlReader.parse().

bool QXmlSimpleReader.parse (self, QXmlInputSource input, bool incremental)

Reimplemented from QXmlReader.parse().

Reads an XML document from input and parses it in one pass (non-incrementally). Returns true if the parsing was successful; otherwise returns false.

bool QXmlSimpleReader.parseContinue (self)

Continues incremental parsing, taking input from the QXmlInputSource that was specified with the most recent call to parse(). To use this function, you must have called parse() with the incremental argument set to true.

Returns false if a parsing error occurs; otherwise returns true, even if the end of the XML file has not been reached. You can continue parsing at a later stage by calling this function again when there is more data available to parse.

Calling this function when there is no data available in the input source indicates to the reader that the end of the XML file has been reached. If the input supplied up to this point was not well-formed then a parsing error occurs, and false is returned. If the input supplied was well-formed, true is returned. It is important to end the input in this way because it allows you to reuse the reader to parse other XML files.

Calling this function after the end of file has been reached, but without available data will cause false to be returned whether the previous input was well-formed or not.

See also parse(), QXmlInputSource.data(), and QXmlInputSource.next().

(sip.voidptr, bool ok) QXmlSimpleReader.property (self, QString name)

Reimplemented from QXmlReader.property().

See also setProperty().

QXmlSimpleReader.setContentHandler (self, QXmlContentHandler handler)

Reimplemented from QXmlReader.setContentHandler().

See also contentHandler().

QXmlSimpleReader.setDeclHandler (self, QXmlDeclHandler handler)

Reimplemented from QXmlReader.setDeclHandler().

See also declHandler().

QXmlSimpleReader.setDTDHandler (self, QXmlDTDHandler handler)

Reimplemented from QXmlReader.setDTDHandler().

QXmlSimpleReader.setEntityResolver (self, QXmlEntityResolver handler)

Reimplemented from QXmlReader.setEntityResolver().

See also entityResolver().

QXmlSimpleReader.setErrorHandler (self, QXmlErrorHandler handler)

Reimplemented from QXmlReader.setErrorHandler().

See also errorHandler().

QXmlSimpleReader.setFeature (self, QString name, bool value)

Reimplemented from QXmlReader.setFeature().

Turns on the feature name if enable is true; otherwise turns it off.

The name parameter must be one of the following strings:

Feature Default Notes
http://xml.org/sax/features/namespaces true If enabled, namespaces are reported to the content handler.
http://xml.org/sax/features/namespace-prefixes false If enabled, the original prefixed names and attributes used for namespace declarations are reported.
http://trolltech.com/xml/features/report-whitespace-only-CharData true If enabled, CharData that consist of only whitespace characters are reported using QXmlContentHandler.characters(). If disabled, whitespace is silently discarded.
http://trolltech.com/xml/features/report-start-end-entity false If enabled, the parser reports QXmlContentHandler.startEntity() and QXmlContentHandler.endEntity() events, so character data might be reported in chunks. If disabled, the parser does not report these events, but silently substitutes the entities, and reports the character data in one chunk.

See also feature(), hasFeature(), and SAX2 Features.

QXmlSimpleReader.setLexicalHandler (self, QXmlLexicalHandler handler)

Reimplemented from QXmlReader.setLexicalHandler().

See also lexicalHandler().

QXmlSimpleReader.setProperty (self, QString name, sip.voidptr value)

Reimplemented from QXmlReader.setProperty().

See also property().

PyQt 4.12.1 for X11Copyright © Riverbank Computing Ltd and The Qt Company 2015Qt 4.8.7