13.5 xml.parsers.expat -- Fast XML parsing using Expat

Python 2.4

previous page next page

13.5 `xml.parsers.expat` -- Fast XML parsing using Expat

New in version 2.0.

The xml.parsers.expat module is a Python interface to the Expat non-validating XML parser. The module provides a single extension type, xmlparser, that represents the current state of an XML parser. After an xmlparser object has been created, various attributes of the object can be set to handler functions. When an XML document is then fed to the parser, the handler functions are called for the character data and markup in the XML document.

This module uses the pyexpat module to provide access to the Expat parser. Direct use of the pyexpat module is deprecated.

This module provides one exception and one type object:

exception ExpatError: The exception raised when Expat reports an error. See section 13.5.2, ``ExpatError Exceptions,'' for more information on interpreting Expat errors.

exception error: Alias for ExpatError.

XMLParserType: The type of the return values from the ParserCreate() function.

The xml.parsers.expat module contains two functions:

ErrorString( errno): Returns an explanatory string for a given error number errno.

ParserCreate( [encoding[, namespace_separator]])

Creates and returns a new xmlparser object. encoding, if specified, must be a string naming the encoding used by the XML data. Expat doesn't support as many encodings as Python does, and its repertoire of encodings can't be extended; it supports UTF-8, UTF-16, ISO-8859-1 (Latin1), and ASCII. If encoding is given it will override the implicit or explicit encoding of the document.

Expat can optionally do XML namespace processing for you, enabled by providing a value for namespace_separator. The value must be a one-character string; a ValueError will be raised if the string has an illegal length (None is considered the same as omission). When namespace processing is enabled, element type names and attribute names that belong to a namespace will be expanded. The element name passed to the element handlers StartElementHandler and EndElementHandler will be the concatenation of the namespace URI, the namespace separator character, and the local part of the name. If the namespace separator is a zero byte (chr(0)) then the namespace URI and the local part will be concatenated without any separator.

For example, if namespace_separator is set to a space character (" ") and the following document is parsed:

<?xml version="1.0"?>
<root xmlns    = "http://default-namespace.org/"
      xmlns:py = "http://www.python.org/ns/">
  <py:elem1 />
  <elem2 xmlns="" />
</root>

StartElementHandler will receive the following strings for each element:

http://default-namespace.org/ root
http://www.python.org/ns/ elem1
elem2