1 :mod:`xml.sax` --- Support for SAX2 parsers 2 =========================================== 3 4 .. module:: xml.sax 5 :synopsis: Package containing SAX2 base classes and convenience functions. 6 7 .. moduleauthor:: Lars Marius Garshol <larsga (a] garshol.priv.no> 8 .. sectionauthor:: Fred L. Drake, Jr. <fdrake (a] acm.org> 9 .. sectionauthor:: Martin v. Lwis <martin (a] v.loewis.de> 10 11 **Source code:** :source:`Lib/xml/sax/__init__.py` 12 13 -------------- 14 15 The :mod:`xml.sax` package provides a number of modules which implement the 16 Simple API for XML (SAX) interface for Python. The package itself provides the 17 SAX exceptions and the convenience functions which will be most used by users of 18 the SAX API. 19 20 21 .. warning:: 22 23 The :mod:`xml.sax` module is not secure against maliciously 24 constructed data. If you need to parse untrusted or unauthenticated data see 25 :ref:`xml-vulnerabilities`. 26 27 28 The convenience functions are: 29 30 31 .. function:: make_parser(parser_list=[]) 32 33 Create and return a SAX :class:`~xml.sax.xmlreader.XMLReader` object. The 34 first parser found will 35 be used. If *parser_list* is provided, it must be a sequence of strings which 36 name modules that have a function named :func:`create_parser`. Modules listed 37 in *parser_list* will be used before modules in the default list of parsers. 38 39 40 .. function:: parse(filename_or_stream, handler, error_handler=handler.ErrorHandler()) 41 42 Create a SAX parser and use it to parse a document. The document, passed in as 43 *filename_or_stream*, can be a filename or a file object. The *handler* 44 parameter needs to be a SAX :class:`~handler.ContentHandler` instance. If 45 *error_handler* is given, it must be a SAX :class:`~handler.ErrorHandler` 46 instance; if 47 omitted, :exc:`SAXParseException` will be raised on all errors. There is no 48 return value; all work must be done by the *handler* passed in. 49 50 51 .. function:: parseString(string, handler, error_handler=handler.ErrorHandler()) 52 53 Similar to :func:`parse`, but parses from a buffer *string* received as a 54 parameter. *string* must be a :class:`str` instance or a 55 :term:`bytes-like object`. 56 57 .. versionchanged:: 3.5 58 Added support of :class:`str` instances. 59 60 A typical SAX application uses three kinds of objects: readers, handlers and 61 input sources. "Reader" in this context is another term for parser, i.e. some 62 piece of code that reads the bytes or characters from the input source, and 63 produces a sequence of events. The events then get distributed to the handler 64 objects, i.e. the reader invokes a method on the handler. A SAX application 65 must therefore obtain a reader object, create or open the input sources, create 66 the handlers, and connect these objects all together. As the final step of 67 preparation, the reader is called to parse the input. During parsing, methods on 68 the handler objects are called based on structural and syntactic events from the 69 input data. 70 71 For these objects, only the interfaces are relevant; they are normally not 72 instantiated by the application itself. Since Python does not have an explicit 73 notion of interface, they are formally introduced as classes, but applications 74 may use implementations which do not inherit from the provided classes. The 75 :class:`~xml.sax.xmlreader.InputSource`, :class:`~xml.sax.xmlreader.Locator`, 76 :class:`~xml.sax.xmlreader.Attributes`, :class:`~xml.sax.xmlreader.AttributesNS`, 77 and :class:`~xml.sax.xmlreader.XMLReader` interfaces are defined in the 78 module :mod:`xml.sax.xmlreader`. The handler interfaces are defined in 79 :mod:`xml.sax.handler`. For convenience, 80 :class:`~xml.sax.xmlreader.InputSource` (which is often 81 instantiated directly) and the handler classes are also available from 82 :mod:`xml.sax`. These interfaces are described below. 83 84 In addition to these classes, :mod:`xml.sax` provides the following exception 85 classes. 86 87 88 .. exception:: SAXException(msg, exception=None) 89 90 Encapsulate an XML error or warning. This class can contain basic error or 91 warning information from either the XML parser or the application: it can be 92 subclassed to provide additional functionality or to add localization. Note 93 that although the handlers defined in the 94 :class:`~xml.sax.handler.ErrorHandler` interface 95 receive instances of this exception, it is not required to actually raise the 96 exception --- it is also useful as a container for information. 97 98 When instantiated, *msg* should be a human-readable description of the error. 99 The optional *exception* parameter, if given, should be ``None`` or an exception 100 that was caught by the parsing code and is being passed along as information. 101 102 This is the base class for the other SAX exception classes. 103 104 105 .. exception:: SAXParseException(msg, exception, locator) 106 107 Subclass of :exc:`SAXException` raised on parse errors. Instances of this 108 class are passed to the methods of the SAX 109 :class:`~xml.sax.handler.ErrorHandler` interface to provide information 110 about the parse error. This class supports the SAX 111 :class:`~xml.sax.xmlreader.Locator` interface as well as the 112 :class:`SAXException` interface. 113 114 115 .. exception:: SAXNotRecognizedException(msg, exception=None) 116 117 Subclass of :exc:`SAXException` raised when a SAX 118 :class:`~xml.sax.xmlreader.XMLReader` is 119 confronted with an unrecognized feature or property. SAX applications and 120 extensions may use this class for similar purposes. 121 122 123 .. exception:: SAXNotSupportedException(msg, exception=None) 124 125 Subclass of :exc:`SAXException` raised when a SAX 126 :class:`~xml.sax.xmlreader.XMLReader` is asked to 127 enable a feature that is not supported, or to set a property to a value that the 128 implementation does not support. SAX applications and extensions may use this 129 class for similar purposes. 130 131 132 .. seealso:: 133 134 `SAX: The Simple API for XML <http://www.saxproject.org/>`_ 135 This site is the focal point for the definition of the SAX API. It provides a 136 Java implementation and online documentation. Links to implementations and 137 historical information are also available. 138 139 Module :mod:`xml.sax.handler` 140 Definitions of the interfaces for application-provided objects. 141 142 Module :mod:`xml.sax.saxutils` 143 Convenience functions for use in SAX applications. 144 145 Module :mod:`xml.sax.xmlreader` 146 Definitions of the interfaces for parser-provided objects. 147 148 149 .. _sax-exception-objects: 150 151 SAXException Objects 152 -------------------- 153 154 The :class:`SAXException` exception class supports the following methods: 155 156 157 .. method:: SAXException.getMessage() 158 159 Return a human-readable message describing the error condition. 160 161 162 .. method:: SAXException.getException() 163 164 Return an encapsulated exception object, or ``None``. 165 166
