1 2 :mod:`xmllib` --- A parser for XML documents 3 ============================================ 4 5 .. module:: xmllib 6 :synopsis: A parser for XML documents. 7 :deprecated: 8 .. moduleauthor:: Sjoerd Mullender <Sjoerd.Mullender (a] cwi.nl> 9 .. sectionauthor:: Sjoerd Mullender <Sjoerd.Mullender (a] cwi.nl> 10 11 12 .. index:: 13 single: XML 14 single: Extensible Markup Language 15 16 .. deprecated:: 2.0 17 Use :mod:`xml.sax` instead. The newer XML package includes full support for XML 18 1.0. 19 20 .. versionchanged:: 1.5.2 21 Added namespace support. 22 23 This module defines a class :class:`XMLParser` which serves as the basis for 24 parsing text files formatted in XML (Extensible Markup Language). 25 26 27 .. class:: XMLParser() 28 29 The :class:`XMLParser` class must be instantiated without arguments. [#]_ 30 31 This class provides the following interface methods and instance variables: 32 33 34 .. attribute:: attributes 35 36 A mapping of element names to mappings. The latter mapping maps attribute 37 names that are valid for the element to the default value of the 38 attribute, or if there is no default to ``None``. The default value is 39 the empty dictionary. This variable is meant to be overridden, not 40 extended since the default is shared by all instances of 41 :class:`XMLParser`. 42 43 44 .. attribute:: elements 45 46 A mapping of element names to tuples. The tuples contain a function for 47 handling the start and end tag respectively of the element, or ``None`` if 48 the method :meth:`unknown_starttag` or :meth:`unknown_endtag` is to be 49 called. The default value is the empty dictionary. This variable is 50 meant to be overridden, not extended since the default is shared by all 51 instances of :class:`XMLParser`. 52 53 54 .. attribute:: entitydefs 55 56 A mapping of entitynames to their values. The default value contains 57 definitions for ``'lt'``, ``'gt'``, ``'amp'``, ``'quot'``, and ``'apos'``. 58 59 60 .. method:: reset() 61 62 Reset the instance. Loses all unprocessed data. This is called 63 implicitly at the instantiation time. 64 65 66 .. method:: setnomoretags() 67 68 Stop processing tags. Treat all following input as literal input (CDATA). 69 70 71 .. method:: setliteral() 72 73 Enter literal mode (CDATA mode). This mode is automatically exited when 74 the close tag matching the last unclosed open tag is encountered. 75 76 77 .. method:: feed(data) 78 79 Feed some text to the parser. It is processed insofar as it consists of 80 complete tags; incomplete data is buffered until more data is fed or 81 :meth:`close` is called. 82 83 84 .. method:: close() 85 86 Force processing of all buffered data as if it were followed by an 87 end-of-file mark. This method may be redefined by a derived class to 88 define additional processing at the end of the input, but the redefined 89 version should always call :meth:`close`. 90 91 92 .. method:: translate_references(data) 93 94 Translate all entity and character references in *data* and return the 95 translated string. 96 97 98 .. method:: getnamespace() 99 100 Return a mapping of namespace abbreviations to namespace URIs that are 101 currently in effect. 102 103 104 .. method:: handle_xml(encoding, standalone) 105 106 This method is called when the ``<?xml ...?>`` tag is processed. The 107 arguments are the values of the encoding and standalone attributes in the 108 tag. Both encoding and standalone are optional. The values passed to 109 :meth:`handle_xml` default to ``None`` and the string ``'no'`` 110 respectively. 111 112 113 .. method:: handle_doctype(tag, pubid, syslit, data) 114 115 .. index:: 116 single: DOCTYPE declaration 117 single: Formal Public Identifier 118 119 This method is called when the ``<!DOCTYPE...>`` declaration is processed. 120 The arguments are the tag name of the root element, the Formal Public 121 Identifier (or ``None`` if not specified), the system identifier, and the 122 uninterpreted contents of the internal DTD subset as a string (or ``None`` 123 if not present). 124 125 126 .. method:: handle_starttag(tag, method, attributes) 127 128 This method is called to handle start tags for which a start tag handler 129 is defined in the instance variable :attr:`elements`. The *tag* argument 130 is the name of the tag, and the *method* argument is the function (method) 131 which should be used to support semantic interpretation of the start tag. 132 The *attributes* argument is a dictionary of attributes, the key being the 133 *name* and the value being the *value* of the attribute found inside the 134 tag's ``<>`` brackets. Character and entity references in the *value* 135 have been interpreted. For instance, for the start tag ``<A 136 HREF="http://www.cwi.nl/">``, this method would be called as 137 ``handle_starttag('A', self.elements['A'][0], {'HREF': 138 'http://www.cwi.nl/'})``. The base implementation simply calls *method* 139 with *attributes* as the only argument. 140 141 142 .. method:: handle_endtag(tag, method) 143 144 This method is called to handle endtags for which an end tag handler is 145 defined in the instance variable :attr:`elements`. The *tag* argument is 146 the name of the tag, and the *method* argument is the function (method) 147 which should be used to support semantic interpretation of the end tag. 148 For instance, for the endtag ``</A>``, this method would be called as 149 ``handle_endtag('A', self.elements['A'][1])``. The base implementation 150 simply calls *method*. 151 152 153 .. method:: handle_data(data) 154 155 This method is called to process arbitrary data. It is intended to be 156 overridden by a derived class; the base class implementation does nothing. 157 158 159 .. method:: handle_charref(ref) 160 161 This method is called to process a character reference of the form 162 ``&#ref;``. *ref* can either be a decimal number, or a hexadecimal number 163 when preceded by an ``'x'``. In the base implementation, *ref* must be a 164 number in the range 0-255. It translates the character to ASCII and calls 165 the method :meth:`handle_data` with the character as argument. If *ref* 166 is invalid or out of range, the method ``unknown_charref(ref)`` is called 167 to handle the error. A subclass must override this method to provide 168 support for character references outside of the ASCII range. 169 170 171 .. method:: handle_comment(comment) 172 173 This method is called when a comment is encountered. The *comment* 174 argument is a string containing the text between the ``<!--`` and ``-->`` 175 delimiters, but not the delimiters themselves. For example, the comment 176 ``<!--text-->`` will cause this method to be called with the argument 177 ``'text'``. The default method does nothing. 178 179 180 .. method:: handle_cdata(data) 181 182 This method is called when a CDATA element is encountered. The *data* 183 argument is a string containing the text between the ``<![CDATA[`` and 184 ``]]>`` delimiters, but not the delimiters themselves. For example, the 185 entity ``<![CDATA[text]]>`` will cause this method to be called with the 186 argument ``'text'``. The default method does nothing, and is intended to 187 be overridden. 188 189 190 .. method:: handle_proc(name, data) 191 192 This method is called when a processing instruction (PI) is encountered. 193 The *name* is the PI target, and the *data* argument is a string 194 containing the text between the PI target and the closing delimiter, but 195 not the delimiter itself. For example, the instruction ``<?XML text?>`` 196 will cause this method to be called with the arguments ``'XML'`` and 197 ``'text'``. The default method does nothing. Note that if a document 198 starts with ``<?xml ..?>``, :meth:`handle_xml` is called to handle it. 199 200 201 .. method:: handle_special(data) 202 203 .. index:: single: ENTITY declaration 204 205 This method is called when a declaration is encountered. The *data* 206 argument is a string containing the text between the ``<!`` and ``>`` 207 delimiters, but not the delimiters themselves. For example, the entity 208 declaration ``<!ENTITY text>`` will cause this method to be called with 209 the argument ``'ENTITY text'``. The default method does nothing. Note 210 that ``<!DOCTYPE ...>`` is handled separately if it is located at the 211 start of the document. 212 213 214 .. method:: syntax_error(message) 215 216 This method is called when a syntax error is encountered. The *message* 217 is a description of what was wrong. The default method raises a 218 :exc:`RuntimeError` exception. If this method is overridden, it is 219 permissible for it to return. This method is only called when the error 220 can be recovered from. Unrecoverable errors raise a :exc:`RuntimeError` 221 without first calling :meth:`syntax_error`. 222 223 224 .. method:: unknown_starttag(tag, attributes) 225 226 This method is called to process an unknown start tag. It is intended to 227 be overridden by a derived class; the base class implementation does nothing. 228 229 230 .. method:: unknown_endtag(tag) 231 232 This method is called to process an unknown end tag. It is intended to be 233 overridden by a derived class; the base class implementation does nothing. 234 235 236 .. method:: unknown_charref(ref) 237 238 This method is called to process unresolvable numeric character 239 references. It is intended to be overridden by a derived class; the base 240 class implementation does nothing. 241 242 243 .. method:: unknown_entityref(ref) 244 245 This method is called to process an unknown entity reference. It is 246 intended to be overridden by a derived class; the base class 247 implementation calls :meth:`syntax_error` to signal an error. 248 249 250 .. seealso:: 251 252 `Extensible Markup Language (XML) 1.0 <http://www.w3.org/TR/REC-xml>`_ 253 The XML specification, published by the World Wide Web Consortium (W3C), defines 254 the syntax and processor requirements for XML. References to additional 255 material on XML, including translations of the specification, are available at 256 http://www.w3.org/XML/. 257 258 `Python and XML Processing <https://www.python.org/topics/xml/>`_ 259 The Python XML Topic Guide provides a great deal of information on using XML 260 from Python and links to other sources of information on XML. 261 262 `SIG for XML Processing in Python <https://www.python.org/sigs/xml-sig/>`_ 263 The Python XML Special Interest Group is developing substantial support for 264 processing XML from Python. 265 266 267 .. _xml-namespace: 268 269 XML Namespaces 270 -------------- 271 272 .. index:: pair: XML; namespaces 273 274 This module has support for XML namespaces as defined in the XML Namespaces 275 proposed recommendation. 276 277 Tag and attribute names that are defined in an XML namespace are handled as if 278 the name of the tag or element consisted of the namespace (the URL that defines 279 the namespace) followed by a space and the name of the tag or attribute. For 280 instance, the tag ``<html xmlns='http://www.w3.org/TR/REC-html40'>`` is treated 281 as if the tag name was ``'http://www.w3.org/TR/REC-html40 html'``, and the tag 282 ``<html:a href='http://frob.com'>`` inside the above mentioned element is 283 treated as if the tag name were ``'http://www.w3.org/TR/REC-html40 a'`` and the 284 attribute name as if it were ``'http://www.w3.org/TR/REC-html40 href'``. 285 286 An older draft of the XML Namespaces proposal is also recognized, but triggers a 287 warning. 288 289 290 .. seealso:: 291 292 `Namespaces in XML <http://www.w3.org/TR/REC-xml-names/>`_ 293 This World Wide Web Consortium recommendation describes the proper syntax and 294 processing requirements for namespaces in XML. 295 296 .. rubric:: Footnotes 297 298 .. [#] Actually, a number of keyword arguments are recognized which influence the 299 parser to accept certain non-standard constructs. The following keyword 300 arguments are currently recognized. The defaults for all of these is ``0`` 301 (false) except for the last one for which the default is ``1`` (true). 302 *accept_unquoted_attributes* (accept certain attribute values without requiring 303 quotes), *accept_missing_endtag_name* (accept end tags that look like ``</>``), 304 *map_case* (map upper case to lower case in tags and attributes), *accept_utf8* 305 (allow UTF-8 characters in input; this is required according to the XML 306 standard, but Python does not as yet deal properly with these characters, so 307 this is not the default), *translate_attribute_references* (don't attempt to 308 translate character and entity references in attribute values). 309 310
