xml.sax — Support for SAX2 parsers¶

Source code: Lib/xml/sax/__init__.py

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 and data are:

xml.sax.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 an iterable 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.

Changed in version 3.8: The parser_list argument can be any iterable, not just a list.

xml.sax.parse(filename_or_stream, handler, errorHandler=handler.ErrorHandler())¶

Create a SAX parser and use it to parse a document. The document, passed in as filename_or_stream, can be a system identifier (a string identifying the input source – typically a file name or a URL), a path-like object, or a file object. A system identifier which does not refer to an existing file is opened with urllib.request.urlopen(). The handler parameter needs to be a SAX ContentHandler instance. If errorHandler 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.

xml.sax.parseString(string, handler, errorHandler=handler.ErrorHandler())¶

Similar to parse(), but parses from a buffer string received as a parameter. string must be a str instance or a bytes-like object.

Changed in version 3.5: Added support of str instances.

xml.sax.default_parser_list¶

The list of the names of modules which are tried by make_parser() after the modules named in its parser_list argument. It contains 'xml.sax.expatreader', or, if the PY_SAX_PARSER environment variable is set and the environment is not ignored, the comma-separated list of module names taken from it.

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, Attributes, AttributesNS, 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 xml.sax.SAXException(msg, exception=None)¶

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 xml.sax.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 xml.sax.SAXNotRecognizedException(msg, exception=None)¶

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 xml.sax.SAXNotSupportedException(msg, exception=None)¶

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.

exception xml.sax.SAXReaderNotAvailable(msg, exception=None)¶

Subclass of SAXNotSupportedException raised when no parser is available. A parser module raises it when it is imported or during parsing if the parser it provides cannot be used, and make_parser() raises it if no module from the tried ones provides a usable parser.