1 2 :mod:`xml.sax` --- Support for SAX2 parsers 3 =========================================== 4 5 .. module:: xml.sax 6 :synopsis: Package containing SAX2 base classes and convenience functions. 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 12 .. versionadded:: 2.0 13 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 17 the SAX API. 18 19 20 .. warning:: 21 22 The :mod:`xml.sax` module is not secure against maliciously 23 constructed data. If you need to parse untrusted or unauthenticated data see 24 :ref:`xml-vulnerabilities`. 25 26 27 The convenience functions are: 28 29 30 .. function:: make_parser([parser_list]) 31 32 Create and return a SAX :class:`~xml.sax.xmlreader.XMLReader` object. The 33 first parser found will 34 be used. If *parser_list* is provided, it must be a sequence of strings which 35 name modules that have a function named :func:`create_parser`. Modules listed 36 in *parser_list* will be used before modules in the default list of parsers. 37 38 39 .. function:: parse(filename_or_stream, handler[, error_handler]) 40 41 Create a SAX parser and use it to parse a document. The document, passed in as 42 *filename_or_stream*, can be a filename or a file object. The *handler* 43 parameter needs to be a SAX :class:`~handler.ContentHandler` instance. If 44 *error_handler* is given, it must be a SAX :class:`~handler.ErrorHandler` 45 instance; if 46 omitted, :exc:`SAXParseException` will be raised on all errors. There is no 47 return value; all work must be done by the *handler* passed in. 48 49 50 .. function:: parseString(string, handler[, error_handler]) 51 52 Similar to :func:`parse`, but parses from a buffer *string* received as a 53 parameter. 54 55 A typical SAX application uses three kinds of objects: readers, handlers and 56 input sources. "Reader" in this context is another term for parser, i.e. some 57 piece of code that reads the bytes or characters from the input source, and 58 produces a sequence of events. The events then get distributed to the handler 59 objects, i.e. the reader invokes a method on the handler. A SAX application 60 must therefore obtain a reader object, create or open the input sources, create 61 the handlers, and connect these objects all together. As the final step of 62 preparation, the reader is called to parse the input. During parsing, methods on 63 the handler objects are called based on structural and syntactic events from the 64 input data. 65 66 For these objects, only the interfaces are relevant; they are normally not 67 instantiated by the application itself. Since Python does not have an explicit 68 notion of interface, they are formally introduced as classes, but applications 69 may use implementations which do not inherit from the provided classes. The 70 :class:`~xml.sax.xmlreader.InputSource`, :class:`~xml.sax.xmlreader.Locator`, 71 :class:`~xml.sax.xmlreader.Attributes`, :class:`~xml.sax.xmlreader.AttributesNS`, 72 and :class:`~xml.sax.xmlreader.XMLReader` interfaces are defined in the 73 module :mod:`xml.sax.xmlreader`. The handler interfaces are defined in 74 :mod:`xml.sax.handler`. For convenience, 75 :class:`~xml.sax.xmlreader.InputSource` (which is often 76 instantiated directly) and the handler classes are also available from 77 :mod:`xml.sax`. These interfaces are described below. 78 79 In addition to these classes, :mod:`xml.sax` provides the following exception 80 classes. 81 82 83 .. exception:: SAXException(msg[, exception]) 84 85 Encapsulate an XML error or warning. This class can contain basic error or 86 warning information from either the XML parser or the application: it can be 87 subclassed to provide additional functionality or to add localization. Note 88 that although the handlers defined in the 89 :class:`~xml.sax.handler.ErrorHandler` interface 90 receive instances of this exception, it is not required to actually raise the 91 exception --- it is also useful as a container for information. 92 93 When instantiated, *msg* should be a human-readable description of the error. 94 The optional *exception* parameter, if given, should be ``None`` or an exception 95 that was caught by the parsing code and is being passed along as information. 96 97 This is the base class for the other SAX exception classes. 98 99 100 .. exception:: SAXParseException(msg, exception, locator) 101 102 Subclass of :exc:`SAXException` raised on parse errors. Instances of this 103 class are passed to the methods of the SAX 104 :class:`~xml.sax.handler.ErrorHandler` interface to provide information 105 about the parse error. This class supports the SAX 106 :class:`~xml.sax.xmlreader.Locator` interface as well as the 107 :class:`SAXException` interface. 108 109 110 .. exception:: SAXNotRecognizedException(msg[, exception]) 111 112 Subclass of :exc:`SAXException` raised when a SAX 113 :class:`~xml.sax.xmlreader.XMLReader` is 114 confronted with an unrecognized feature or property. SAX applications and 115 extensions may use this class for similar purposes. 116 117 118 .. exception:: SAXNotSupportedException(msg[, exception]) 119 120 Subclass of :exc:`SAXException` raised when a SAX 121 :class:`~xml.sax.xmlreader.XMLReader` is asked to 122 enable a feature that is not supported, or to set a property to a value that the 123 implementation does not support. SAX applications and extensions may use this 124 class for similar purposes. 125 126 127 .. seealso:: 128 129 `SAX: The Simple API for XML <http://www.saxproject.org/>`_ 130 This site is the focal point for the definition of the SAX API. It provides a 131 Java implementation and online documentation. Links to implementations and 132 historical information are also available. 133 134 Module :mod:`xml.sax.handler` 135 Definitions of the interfaces for application-provided objects. 136 137 Module :mod:`xml.sax.saxutils` 138 Convenience functions for use in SAX applications. 139 140 Module :mod:`xml.sax.xmlreader` 141 Definitions of the interfaces for parser-provided objects. 142 143 144 .. _sax-exception-objects: 145 146 SAXException Objects 147 -------------------- 148 149 The :class:`SAXException` exception class supports the following methods: 150 151 152 .. method:: SAXException.getMessage() 153 154 Return a human-readable message describing the error condition. 155 156 157 .. method:: SAXException.getException() 158 159 Return an encapsulated exception object, or ``None``. 160 161
