1:mod:`xml.sax.xmlreader` --- Interface for XML parsers 2====================================================== 3 4.. module:: xml.sax.xmlreader 5 :synopsis: Interface which SAX-compliant XML parsers must implement. 6 7.. moduleauthor:: Lars Marius Garshol <larsga@garshol.priv.no> 8.. sectionauthor:: Martin v. Löwis <martin@v.loewis.de> 9 10**Source code:** :source:`Lib/xml/sax/xmlreader.py` 11 12-------------- 13 14SAX parsers implement the :class:`XMLReader` interface. They are implemented in 15a Python module, which must provide a function :func:`create_parser`. This 16function is invoked by :func:`xml.sax.make_parser` with no arguments to create 17a new parser object. 18 19 20.. class:: XMLReader() 21 22 Base class which can be inherited by SAX parsers. 23 24 25.. class:: IncrementalParser() 26 27 In some cases, it is desirable not to parse an input source at once, but to feed 28 chunks of the document as they get available. Note that the reader will normally 29 not read the entire file, but read it in chunks as well; still :meth:`parse` 30 won't return until the entire document is processed. So these interfaces should 31 be used if the blocking behaviour of :meth:`parse` is not desirable. 32 33 When the parser is instantiated it is ready to begin accepting data from the 34 feed method immediately. After parsing has been finished with a call to close 35 the reset method must be called to make the parser ready to accept new data, 36 either from feed or using the parse method. 37 38 Note that these methods must *not* be called during parsing, that is, after 39 parse has been called and before it returns. 40 41 By default, the class also implements the parse method of the XMLReader 42 interface using the feed, close and reset methods of the IncrementalParser 43 interface as a convenience to SAX 2.0 driver writers. 44 45 46.. class:: Locator() 47 48 Interface for associating a SAX event with a document location. A locator object 49 will return valid results only during calls to DocumentHandler methods; at any 50 other time, the results are unpredictable. If information is not available, 51 methods may return ``None``. 52 53 54.. class:: InputSource(system_id=None) 55 56 Encapsulation of the information needed by the :class:`XMLReader` to read 57 entities. 58 59 This class may include information about the public identifier, system 60 identifier, byte stream (possibly with character encoding information) and/or 61 the character stream of an entity. 62 63 Applications will create objects of this class for use in the 64 :meth:`XMLReader.parse` method and for returning from 65 EntityResolver.resolveEntity. 66 67 An :class:`InputSource` belongs to the application, the :class:`XMLReader` is 68 not allowed to modify :class:`InputSource` objects passed to it from the 69 application, although it may make copies and modify those. 70 71 72.. class:: AttributesImpl(attrs) 73 74 This is an implementation of the :class:`Attributes` interface (see section 75 :ref:`attributes-objects`). This is a dictionary-like object which 76 represents the element attributes in a :meth:`startElement` call. In addition 77 to the most useful dictionary operations, it supports a number of other 78 methods as described by the interface. Objects of this class should be 79 instantiated by readers; *attrs* must be a dictionary-like object containing 80 a mapping from attribute names to attribute values. 81 82 83.. class:: AttributesNSImpl(attrs, qnames) 84 85 Namespace-aware variant of :class:`AttributesImpl`, which will be passed to 86 :meth:`startElementNS`. It is derived from :class:`AttributesImpl`, but 87 understands attribute names as two-tuples of *namespaceURI* and 88 *localname*. In addition, it provides a number of methods expecting qualified 89 names as they appear in the original document. This class implements the 90 :class:`AttributesNS` interface (see section :ref:`attributes-ns-objects`). 91 92 93.. _xmlreader-objects: 94 95XMLReader Objects 96----------------- 97 98The :class:`XMLReader` interface supports the following methods: 99 100 101.. method:: XMLReader.parse(source) 102 103 Process an input source, producing SAX events. The *source* object can be a 104 system identifier (a string identifying the input source -- typically a file 105 name or a URL), a :class:`pathlib.Path` or :term:`path-like <path-like object>` 106 object, or an :class:`InputSource` object. When 107 :meth:`parse` returns, the input is completely processed, and the parser object 108 can be discarded or reset. 109 110 .. versionchanged:: 3.5 111 Added support of character streams. 112 113 .. versionchanged:: 3.8 114 Added support of path-like objects. 115 116 117.. method:: XMLReader.getContentHandler() 118 119 Return the current :class:`~xml.sax.handler.ContentHandler`. 120 121 122.. method:: XMLReader.setContentHandler(handler) 123 124 Set the current :class:`~xml.sax.handler.ContentHandler`. If no 125 :class:`~xml.sax.handler.ContentHandler` is set, content events will be 126 discarded. 127 128 129.. method:: XMLReader.getDTDHandler() 130 131 Return the current :class:`~xml.sax.handler.DTDHandler`. 132 133 134.. method:: XMLReader.setDTDHandler(handler) 135 136 Set the current :class:`~xml.sax.handler.DTDHandler`. If no 137 :class:`~xml.sax.handler.DTDHandler` is set, DTD 138 events will be discarded. 139 140 141.. method:: XMLReader.getEntityResolver() 142 143 Return the current :class:`~xml.sax.handler.EntityResolver`. 144 145 146.. method:: XMLReader.setEntityResolver(handler) 147 148 Set the current :class:`~xml.sax.handler.EntityResolver`. If no 149 :class:`~xml.sax.handler.EntityResolver` is set, 150 attempts to resolve an external entity will result in opening the system 151 identifier for the entity, and fail if it is not available. 152 153 154.. method:: XMLReader.getErrorHandler() 155 156 Return the current :class:`~xml.sax.handler.ErrorHandler`. 157 158 159.. method:: XMLReader.setErrorHandler(handler) 160 161 Set the current error handler. If no :class:`~xml.sax.handler.ErrorHandler` 162 is set, errors will be raised as exceptions, and warnings will be printed. 163 164 165.. method:: XMLReader.setLocale(locale) 166 167 Allow an application to set the locale for errors and warnings. 168 169 SAX parsers are not required to provide localization for errors and warnings; if 170 they cannot support the requested locale, however, they must raise a SAX 171 exception. Applications may request a locale change in the middle of a parse. 172 173 174.. method:: XMLReader.getFeature(featurename) 175 176 Return the current setting for feature *featurename*. If the feature is not 177 recognized, :exc:`SAXNotRecognizedException` is raised. The well-known 178 featurenames are listed in the module :mod:`xml.sax.handler`. 179 180 181.. method:: XMLReader.setFeature(featurename, value) 182 183 Set the *featurename* to *value*. If the feature is not recognized, 184 :exc:`SAXNotRecognizedException` is raised. If the feature or its setting is not 185 supported by the parser, *SAXNotSupportedException* is raised. 186 187 188.. method:: XMLReader.getProperty(propertyname) 189 190 Return the current setting for property *propertyname*. If the property is not 191 recognized, a :exc:`SAXNotRecognizedException` is raised. The well-known 192 propertynames are listed in the module :mod:`xml.sax.handler`. 193 194 195.. method:: XMLReader.setProperty(propertyname, value) 196 197 Set the *propertyname* to *value*. If the property is not recognized, 198 :exc:`SAXNotRecognizedException` is raised. If the property or its setting is 199 not supported by the parser, *SAXNotSupportedException* is raised. 200 201 202.. _incremental-parser-objects: 203 204IncrementalParser Objects 205------------------------- 206 207Instances of :class:`IncrementalParser` offer the following additional methods: 208 209 210.. method:: IncrementalParser.feed(data) 211 212 Process a chunk of *data*. 213 214 215.. method:: IncrementalParser.close() 216 217 Assume the end of the document. That will check well-formedness conditions that 218 can be checked only at the end, invoke handlers, and may clean up resources 219 allocated during parsing. 220 221 222.. method:: IncrementalParser.reset() 223 224 This method is called after close has been called to reset the parser so that it 225 is ready to parse new documents. The results of calling parse or feed after 226 close without calling reset are undefined. 227 228 229.. _locator-objects: 230 231Locator Objects 232--------------- 233 234Instances of :class:`Locator` provide these methods: 235 236 237.. method:: Locator.getColumnNumber() 238 239 Return the column number where the current event begins. 240 241 242.. method:: Locator.getLineNumber() 243 244 Return the line number where the current event begins. 245 246 247.. method:: Locator.getPublicId() 248 249 Return the public identifier for the current event. 250 251 252.. method:: Locator.getSystemId() 253 254 Return the system identifier for the current event. 255 256 257.. _input-source-objects: 258 259InputSource Objects 260------------------- 261 262 263.. method:: InputSource.setPublicId(id) 264 265 Sets the public identifier of this :class:`InputSource`. 266 267 268.. method:: InputSource.getPublicId() 269 270 Returns the public identifier of this :class:`InputSource`. 271 272 273.. method:: InputSource.setSystemId(id) 274 275 Sets the system identifier of this :class:`InputSource`. 276 277 278.. method:: InputSource.getSystemId() 279 280 Returns the system identifier of this :class:`InputSource`. 281 282 283.. method:: InputSource.setEncoding(encoding) 284 285 Sets the character encoding of this :class:`InputSource`. 286 287 The encoding must be a string acceptable for an XML encoding declaration (see 288 section 4.3.3 of the XML recommendation). 289 290 The encoding attribute of the :class:`InputSource` is ignored if the 291 :class:`InputSource` also contains a character stream. 292 293 294.. method:: InputSource.getEncoding() 295 296 Get the character encoding of this InputSource. 297 298 299.. method:: InputSource.setByteStream(bytefile) 300 301 Set the byte stream (a :term:`binary file`) for this input source. 302 303 The SAX parser will ignore this if there is also a character stream specified, 304 but it will use a byte stream in preference to opening a URI connection itself. 305 306 If the application knows the character encoding of the byte stream, it should 307 set it with the setEncoding method. 308 309 310.. method:: InputSource.getByteStream() 311 312 Get the byte stream for this input source. 313 314 The getEncoding method will return the character encoding for this byte stream, 315 or ``None`` if unknown. 316 317 318.. method:: InputSource.setCharacterStream(charfile) 319 320 Set the character stream (a :term:`text file`) for this input source. 321 322 If there is a character stream specified, the SAX parser will ignore any byte 323 stream and will not attempt to open a URI connection to the system identifier. 324 325 326.. method:: InputSource.getCharacterStream() 327 328 Get the character stream for this input source. 329 330 331.. _attributes-objects: 332 333The :class:`Attributes` Interface 334--------------------------------- 335 336:class:`Attributes` objects implement a portion of the :term:`mapping protocol 337<mapping>`, including the methods :meth:`~collections.abc.Mapping.copy`, 338:meth:`~collections.abc.Mapping.get`, :meth:`~object.__contains__`, 339:meth:`~collections.abc.Mapping.items`, :meth:`~collections.abc.Mapping.keys`, 340and :meth:`~collections.abc.Mapping.values`. The following methods 341are also provided: 342 343 344.. method:: Attributes.getLength() 345 346 Return the number of attributes. 347 348 349.. method:: Attributes.getNames() 350 351 Return the names of the attributes. 352 353 354.. method:: Attributes.getType(name) 355 356 Returns the type of the attribute *name*, which is normally ``'CDATA'``. 357 358 359.. method:: Attributes.getValue(name) 360 361 Return the value of attribute *name*. 362 363.. getValueByQName, getNameByQName, getQNameByName, getQNames available 364.. here already, but documented only for derived class. 365 366 367.. _attributes-ns-objects: 368 369The :class:`AttributesNS` Interface 370----------------------------------- 371 372This interface is a subtype of the :class:`Attributes` interface (see section 373:ref:`attributes-objects`). All methods supported by that interface are also 374available on :class:`AttributesNS` objects. 375 376The following methods are also available: 377 378 379.. method:: AttributesNS.getValueByQName(name) 380 381 Return the value for a qualified name. 382 383 384.. method:: AttributesNS.getNameByQName(name) 385 386 Return the ``(namespace, localname)`` pair for a qualified *name*. 387 388 389.. method:: AttributesNS.getQNameByName(name) 390 391 Return the qualified name for a ``(namespace, localname)`` pair. 392 393 394.. method:: AttributesNS.getQNames() 395 396 Return the qualified names of all attributes. 397 398