New in version 2.0.
The xml.sax package provides a number of modules which
implement the Simple API for XML (SAX) interface for Python. The
package itself provides the SAX exceptions and the convenience
functions which will be most used by users of the SAX API.
The convenience functions are:
- make_parser([parser_list])
-
Create and return a SAX XMLReader object. The first parser
found will be used. If parser_list is provided, it must be a
sequence of strings which name modules that have a function named
create_parser(). Modules listed in parser_list
will be used before modules in the default list of parsers.
- parse(filename_or_stream, handler[, error_handler])
-
Create a SAX parser and use it to parse a document. The document,
passed in as filename_or_stream, can be a filename or a file
object. The handler parameter needs to be a SAX
ContentHandler instance. If error_handler is given,
it must be a SAX ErrorHandler instance; if omitted,
SAXParseException will be raised on all errors. There
is no return value; all work must be done by the handler
passed in.
- parseString(string, handler[, error_handler])
-
Similar to parse(), but parses from a buffer string
received as a parameter.
A typical SAX application uses three kinds of objects: readers,
handlers and input sources. ``Reader'' in this context is another
term for parser, i.e. some piece of code that reads the bytes or
characters from the input source, and produces a sequence of events.
The events then get distributed to the handler objects, i.e. the
reader invokes a method on the handler. A SAX application must
therefore obtain a reader object, create or open the input sources,
create the handlers, and connect these objects all together. As the
final step of preparation, the reader is called to parse the input.
During parsing, methods on the handler objects are called based on
structural and syntactic events from the input data.
For these objects, only the interfaces are relevant; they are normally
not instantiated by the application itself. Since Python does not have
an explicit notion of interface, they are formally introduced as
classes, but applications may use implementations which do not inherit
from the provided classes. The InputSource, Locator,
AttributesImpl, AttributesNSImpl, and
XMLReader interfaces are defined in the module
xml.sax.xmlreader. The handler interfaces are defined in
xml.sax.handler. For convenience, InputSource
(which is often instantiated directly) and the handler classes are
also available from xml.sax. These interfaces are described
below.
In addition to these classes, xml.sax provides the following
exception classes.
- exception SAXException(msg[, 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 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, msg should be a human-readable description
of the error. The optional exception parameter, if given,
should be 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.
- exception SAXParseException(msg, exception, locator)
-
Subclass of SAXException raised on parse errors.
Instances of this class are passed to the methods of the SAX
ErrorHandler interface to provide information about the
parse error. This class supports the SAX Locator interface
as well as the SAXException interface.
- exception SAXNotRecognizedException(msg[, exception])
-
Subclass of SAXException raised when a SAX
XMLReader is confronted with an unrecognized feature or
property. SAX applications and extensions may use this class for
similar purposes.
- exception SAXNotSupportedException(msg[, exception])
-
Subclass of SAXException raised when a SAX
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.
See Also:
- 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.
Subsections
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