2 :mod:`xml.sax` --- Support for SAX2 parsers
3 ===========================================
6 :synopsis: Package containing SAX2 base classes and convenience functions.
7 .. moduleauthor:: Lars Marius Garshol <larsga@garshol.priv.no>
8 .. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
9 .. sectionauthor:: Martin v. Löwis <martin@v.loewis.de>
14 The :mod:`xml.sax` package provides a number of modules which implement the
15 Simple API for XML (SAX) interface for Python. The package itself provides the
16 SAX exceptions and the convenience functions which will be most used by users of
19 The convenience functions are:
22 .. function:: make_parser([parser_list])
24 Create and return a SAX :class:`XMLReader` object. The first parser found will
25 be used. If *parser_list* is provided, it must be a sequence of strings which
26 name modules that have a function named :func:`create_parser`. Modules listed
27 in *parser_list* will be used before modules in the default list of parsers.
30 .. function:: parse(filename_or_stream, handler[, error_handler])
32 Create a SAX parser and use it to parse a document. The document, passed in as
33 *filename_or_stream*, can be a filename or a file object. The *handler*
34 parameter needs to be a SAX :class:`ContentHandler` instance. If
35 *error_handler* is given, it must be a SAX :class:`ErrorHandler` instance; if
36 omitted, :exc:`SAXParseException` will be raised on all errors. There is no
37 return value; all work must be done by the *handler* passed in.
40 .. function:: parseString(string, handler[, error_handler])
42 Similar to :func:`parse`, but parses from a buffer *string* received as a
45 A typical SAX application uses three kinds of objects: readers, handlers and
46 input sources. "Reader" in this context is another term for parser, i.e. some
47 piece of code that reads the bytes or characters from the input source, and
48 produces a sequence of events. The events then get distributed to the handler
49 objects, i.e. the reader invokes a method on the handler. A SAX application
50 must therefore obtain a reader object, create or open the input sources, create
51 the handlers, and connect these objects all together. As the final step of
52 preparation, the reader is called to parse the input. During parsing, methods on
53 the handler objects are called based on structural and syntactic events from the
56 For these objects, only the interfaces are relevant; they are normally not
57 instantiated by the application itself. Since Python does not have an explicit
58 notion of interface, they are formally introduced as classes, but applications
59 may use implementations which do not inherit from the provided classes. The
60 :class:`InputSource`, :class:`Locator`, :class:`Attributes`,
61 :class:`AttributesNS`, and :class:`XMLReader` interfaces are defined in the
62 module :mod:`xml.sax.xmlreader`. The handler interfaces are defined in
63 :mod:`xml.sax.handler`. For convenience, :class:`InputSource` (which is often
64 instantiated directly) and the handler classes are also available from
65 :mod:`xml.sax`. These interfaces are described below.
67 In addition to these classes, :mod:`xml.sax` provides the following exception
71 .. exception:: SAXException(msg[, exception])
73 Encapsulate an XML error or warning. This class can contain basic error or
74 warning information from either the XML parser or the application: it can be
75 subclassed to provide additional functionality or to add localization. Note
76 that although the handlers defined in the :class:`ErrorHandler` interface
77 receive instances of this exception, it is not required to actually raise the
78 exception --- it is also useful as a container for information.
80 When instantiated, *msg* should be a human-readable description of the error.
81 The optional *exception* parameter, if given, should be ``None`` or an exception
82 that was caught by the parsing code and is being passed along as information.
84 This is the base class for the other SAX exception classes.
87 .. exception:: SAXParseException(msg, exception, locator)
89 Subclass of :exc:`SAXException` raised on parse errors. Instances of this class
90 are passed to the methods of the SAX :class:`ErrorHandler` interface to provide
91 information about the parse error. This class supports the SAX :class:`Locator`
92 interface as well as the :class:`SAXException` interface.
95 .. exception:: SAXNotRecognizedException(msg[, exception])
97 Subclass of :exc:`SAXException` raised when a SAX :class:`XMLReader` is
98 confronted with an unrecognized feature or property. SAX applications and
99 extensions may use this class for similar purposes.
102 .. exception:: SAXNotSupportedException(msg[, exception])
104 Subclass of :exc:`SAXException` raised when a SAX :class:`XMLReader` is asked to
105 enable a feature that is not supported, or to set a property to a value that the
106 implementation does not support. SAX applications and extensions may use this
107 class for similar purposes.
112 `SAX: The Simple API for XML <http://www.saxproject.org/>`_
113 This site is the focal point for the definition of the SAX API. It provides a
114 Java implementation and online documentation. Links to implementations and
115 historical information are also available.
117 Module :mod:`xml.sax.handler`
118 Definitions of the interfaces for application-provided objects.
120 Module :mod:`xml.sax.saxutils`
121 Convenience functions for use in SAX applications.
123 Module :mod:`xml.sax.xmlreader`
124 Definitions of the interfaces for parser-provided objects.
127 .. _sax-exception-objects:
132 The :class:`SAXException` exception class supports the following methods:
135 .. method:: SAXException.getMessage()
137 Return a human-readable message describing the error condition.
140 .. method:: SAXException.getException()
142 Return an encapsulated exception object, or ``None``.