\section{\module{xml.sax} ---         Support for SAX2 parsers} \declaremodule{standard}{xml.sax}\modulesynopsis{Package containing SAX2 base classes and convenience                functions.}\moduleauthor{Lars Marius Garshol}{larsga@garshol.priv.no}\sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}\sectionauthor{Martin v. L\"owis}{martin@v.loewis.de} \versionadded{2.0}  The \module{xml.sax} package provides a number of modules whichimplement the Simple API for XML (SAX) interface for Python.  Thepackage itself provides the SAX exceptions and the conveniencefunctions which will be most used by users of the SAX API. The convenience functions are: \begin{funcdesc}{make_parser}{\optional{parser_list}}  Create and return a SAX \class{XMLReader} object.  The first parser  found will be used.  If \var{parser_list} is provided, it must be a  sequence of strings which name modules that have a function named  \function{create_parser()}.  Modules listed in \var{parser_list}  will be used before modules in the default list of parsers.\end{funcdesc} \begin{funcdesc}{parse}{filename_or_stream, handler\optional{, error_handler}}  Create a SAX parser and use it to parse a document.  The document,  passed in as \var{filename_or_stream}, can be a filename or a file  object.  The \var{handler} parameter needs to be a SAX  \class{ContentHandler} instance.  If \var{error_handler} is given,  it must be a SAX \class{ErrorHandler} instance; if omitted,   \exception{SAXParseException} will be raised on all errors.  There  is no return value; all work must be done by the \var{handler}  passed in.\end{funcdesc} \begin{funcdesc}{parseString}{string, handler\optional{, error_handler}}  Similar to \function{parse()}, but parses from a buffer \var{string}  received as a parameter.\end{funcdesc} A typical SAX application uses three kinds of objects: readers,handlers and input sources.  ``Reader'' in this context is anotherterm for parser, i.e.\ some piece of code that reads the bytes orcharacters from the input source, and produces a sequence of events.The events then get distributed to the handler objects, i.e.\ thereader invokes a method on the handler.  A SAX application musttherefore obtain a reader object, create or open the input sources,create the handlers, and connect these objects all together.  As thefinal step of preparation, the reader is called to parse the input.During parsing, methods on the handler objects are called based onstructural and syntactic events from the input data. For these objects, only the interfaces are relevant; they are normallynot instantiated by the application itself.  Since Python does not havean explicit notion of interface, they are formally introduced asclasses, but applications may use implementations which do not inheritfrom the provided classes.  The \class{InputSource}, \class{Locator},\class{Attributes}, \class{AttributesNS}, and\class{XMLReader} interfaces are defined in the module\refmodule{xml.sax.xmlreader}.  The handler interfaces are defined in\refmodule{xml.sax.handler}.  For convenience, \class{InputSource}(which is often instantiated directly) and the handler classes arealso available from \module{xml.sax}.  These interfaces are describedbelow. In addition to these classes, \module{xml.sax} provides the followingexception classes. \begin{excclassdesc}{SAXException}{msg\optional{, exception}}  Encapsulate an XML error or warning.  This class can contain basic  error or warning information from either the XML parser or the  application: it can be subclassed to provide additional  functionality or to add localization.  Note that although the  handlers defined in the \class{ErrorHandler} interface receive  instances of this exception, it is not required to actually raise  the exception --- it is also useful as a container for information.   When instantiated, \var{msg} should be a human-readable description  of the error.  The optional \var{exception} parameter, if given,  should be \code{None} or an exception that was caught by the parsing  code and is being passed along as information.   This is the base class for the other SAX exception classes.\end{excclassdesc} \begin{excclassdesc}{SAXParseException}{msg, exception, locator}  Subclass of \exception{SAXException} raised on parse errors.  Instances of this class are passed to the methods of the SAX  \class{ErrorHandler} interface to provide information about the  parse error.  This class supports the SAX \class{Locator} interface  as well as the \class{SAXException} interface.\end{excclassdesc} \begin{excclassdesc}{SAXNotRecognizedException}{msg\optional{, exception}}  Subclass of \exception{SAXException} raised when a SAX  \class{XMLReader} is confronted with an unrecognized feature or  property.  SAX applications and extensions may use this class for  similar purposes.\end{excclassdesc} \begin{excclassdesc}{SAXNotSupportedException}{msg\optional{, exception}}  Subclass of \exception{SAXException} raised when a SAX  \class{XMLReader} is asked to enable a feature that is not  supported, or to set a property to a value that the implementation  does not support.  SAX applications and extensions may use this  class for similar purposes.\end{excclassdesc}  \begin{seealso}  \seetitle[http://www.saxproject.org/]{SAX: The Simple API for            XML}{This site is the focal point for the definition of            the SAX API.  It provides a Java implementation and online            documentation.  Links to implementations and historical            information are also available.}   \seemodule{xml.sax.handler}{Definitions of the interfaces for             application-provided objects.}   \seemodule{xml.sax.saxutils}{Convenience functions for use in SAX             applications.}   \seemodule{xml.sax.xmlreader}{Definitions of the interfaces for             parser-provided objects.}\end{seealso}  \subsection{SAXException Objects \label{sax-exception-objects}} The \class{SAXException} exception class supports the followingmethods: \begin{methoddesc}[SAXException]{getMessage}{}  Return a human-readable message describing the error condition.\end{methoddesc} \begin{methoddesc}[SAXException]{getException}{}  Return an encapsulated exception object, or \code{None}.\end{methoddesc}