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  1
  2:mod:`xml.parsers.expat` --- Fast XML parsing using Expat
  3=========================================================
  4
  5.. module:: xml.parsers.expat
  6   :synopsis: An interface to the Expat non-validating XML parser.
  7.. moduleauthor:: Paul Prescod <paul@prescod.net>
  8
  9
 10.. Markup notes:
 11
 12   Many of the attributes of the XMLParser objects are callbacks.  Since
 13   signature information must be presented, these are described using the method
 14   directive.  Since they are attributes which are set by client code, in-text
 15   references to these attributes should be marked using the :member: role.
 16
 17.. versionadded:: 2.0
 18
 19.. index:: single: Expat
 20
 21The :mod:`xml.parsers.expat` module is a Python interface to the Expat
 22non-validating XML parser. The module provides a single extension type,
 23:class:`xmlparser`, that represents the current state of an XML parser.  After
 24an :class:`xmlparser` object has been created, various attributes of the object
 25can be set to handler functions.  When an XML document is then fed to the
 26parser, the handler functions are called for the character data and markup in
 27the XML document.
 28
 29.. index:: module: pyexpat
 30
 31This module uses the :mod:`pyexpat` module to provide access to the Expat
 32parser.  Direct use of the :mod:`pyexpat` module is deprecated.
 33
 34This module provides one exception and one type object:
 35
 36
 37.. exception:: ExpatError
 38
 39   The exception raised when Expat reports an error.  See section
 40   :ref:`expaterror-objects` for more information on interpreting Expat errors.
 41
 42
 43.. exception:: error
 44
 45   Alias for :exc:`ExpatError`.
 46
 47
 48.. data:: XMLParserType
 49
 50   The type of the return values from the :func:`ParserCreate` function.
 51
 52The :mod:`xml.parsers.expat` module contains two functions:
 53
 54
 55.. function:: ErrorString(errno)
 56
 57   Returns an explanatory string for a given error number *errno*.
 58
 59
 60.. function:: ParserCreate([encoding[, namespace_separator]])
 61
 62   Creates and returns a new :class:`xmlparser` object.   *encoding*, if specified,
 63   must be a string naming the encoding  used by the XML data.  Expat doesn't
 64   support as many encodings as Python does, and its repertoire of encodings can't
 65   be extended; it supports UTF-8, UTF-16, ISO-8859-1 (Latin1), and ASCII.  If
 66   *encoding* [1]_ is given it will override the implicit or explicit encoding of the
 67   document.
 68
 69   Expat can optionally do XML namespace processing for you, enabled by providing a
 70   value for *namespace_separator*.  The value must be a one-character string; a
 71   :exc:`ValueError` will be raised if the string has an illegal length (``None``
 72   is considered the same as omission).  When namespace processing is enabled,
 73   element type names and attribute names that belong to a namespace will be
 74   expanded.  The element name passed to the element handlers
 75   :attr:`StartElementHandler` and :attr:`EndElementHandler` will be the
 76   concatenation of the namespace URI, the namespace separator character, and the
 77   local part of the name.  If the namespace separator is a zero byte (``chr(0)``)
 78   then the namespace URI and the local part will be concatenated without any
 79   separator.
 80
 81   For example, if *namespace_separator* is set to a space character (``' '``) and
 82   the following document is parsed::
 83
 84      <?xml version="1.0"?>
 85      <root xmlns    = "http://default-namespace.org/"
 86            xmlns:py = "http://www.python.org/ns/">
 87        <py:elem1 />
 88        <elem2 xmlns="" />
 89      </root>
 90
 91   :attr:`StartElementHandler` will receive the following strings for each
 92   element::
 93
 94      http://default-namespace.org/ root
 95      http://www.python.org/ns/ elem1
 96      elem2
 97
 98
 99.. seealso::
100
101   `The Expat XML Parser <http://www.libexpat.org/>`_
102      Home page of the Expat project.
103
104
105.. _xmlparser-objects:
106
107XMLParser Objects
108-----------------
109
110:class:`xmlparser` objects have the following methods:
111
112
113.. method:: xmlparser.Parse(data[, isfinal])
114
115   Parses the contents of the string *data*, calling the appropriate handler
116   functions to process the parsed data.  *isfinal* must be true on the final call
117   to this method.  *data* can be the empty string at any time.
118
119
120.. method:: xmlparser.ParseFile(file)
121
122   Parse XML data reading from the object *file*.  *file* only needs to provide
123   the ``read(nbytes)`` method, returning the empty string when there's no more
124   data.
125
126
127.. method:: xmlparser.SetBase(base)
128
129   Sets the base to be used for resolving relative URIs in system identifiers in
130   declarations.  Resolving relative identifiers is left to the application: this
131   value will be passed through as the *base* argument to the
132   :func:`ExternalEntityRefHandler`, :func:`NotationDeclHandler`, and
133   :func:`UnparsedEntityDeclHandler` functions.
134
135
136.. method:: xmlparser.GetBase()
137
138   Returns a string containing the base set by a previous call to :meth:`SetBase`,
139   or ``None`` if  :meth:`SetBase` hasn't been called.
140
141
142.. method:: xmlparser.GetInputContext()
143
144   Returns the input data that generated the current event as a string. The data is
145   in the encoding of the entity which contains the text. When called while an
146   event handler is not active, the return value is ``None``.
147
148   .. versionadded:: 2.1
149
150
151.. method:: xmlparser.ExternalEntityParserCreate(context[, encoding])
152
153   Create a "child" parser which can be used to parse an external parsed entity
154   referred to by content parsed by the parent parser.  The *context* parameter
155   should be the string passed to the :meth:`ExternalEntityRefHandler` handler
156   function, described below. The child parser is created with the
157   :attr:`ordered_attributes`, :attr:`returns_unicode` and
158   :attr:`specified_attributes` set to the values of this parser.
159
160
161.. method:: xmlparser.UseForeignDTD([flag])
162
163   Calling this with a true value for *flag* (the default) will cause Expat to call
164   the :attr:`ExternalEntityRefHandler` with :const:`None` for all arguments to
165   allow an alternate DTD to be loaded.  If the document does not contain a
166   document type declaration, the :attr:`ExternalEntityRefHandler` will still be
167   called, but the :attr:`StartDoctypeDeclHandler` and
168   :attr:`EndDoctypeDeclHandler` will not be called.
169
170   Passing a false value for *flag* will cancel a previous call that passed a true
171   value, but otherwise has no effect.
172
173   This method can only be called before the :meth:`Parse` or :meth:`ParseFile`
174   methods are called; calling it after either of those have been called causes
175   :exc:`ExpatError` to be raised with the :attr:`code` attribute set to
176   :const:`errors.XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING`.
177
178   .. versionadded:: 2.3
179
180:class:`xmlparser` objects have the following attributes:
181
182
183.. attribute:: xmlparser.buffer_size
184
185   The size of the buffer used when :attr:`buffer_text` is true.
186   A new buffer size can be set by assigning a new integer value
187   to this attribute.
188   When the size is changed, the buffer will be flushed.
189
190   .. versionadded:: 2.3
191
192   .. versionchanged:: 2.6
193      The buffer size can now be changed.
194
195.. attribute:: xmlparser.buffer_text
196
197   Setting this to true causes the :class:`xmlparser` object to buffer textual
198   content returned by Expat to avoid multiple calls to the
199   :meth:`CharacterDataHandler` callback whenever possible.  This can improve
200   performance substantially since Expat normally breaks character data into chunks
201   at every line ending.  This attribute is false by default, and may be changed at
202   any time.
203
204   .. versionadded:: 2.3
205
206
207.. attribute:: xmlparser.buffer_used
208
209   If :attr:`buffer_text` is enabled, the number of bytes stored in the buffer.
210   These bytes represent UTF-8 encoded text.  This attribute has no meaningful
211   interpretation when :attr:`buffer_text` is false.
212
213   .. versionadded:: 2.3
214
215
216.. attribute:: xmlparser.ordered_attributes
217
218   Setting this attribute to a non-zero integer causes the attributes to be
219   reported as a list rather than a dictionary.  The attributes are presented in
220   the order found in the document text.  For each attribute, two list entries are
221   presented: the attribute name and the attribute value.  (Older versions of this
222   module also used this format.)  By default, this attribute is false; it may be
223   changed at any time.
224
225   .. versionadded:: 2.1
226
227
228.. attribute:: xmlparser.returns_unicode
229
230   If this attribute is set to a non-zero integer, the handler functions will be
231   passed Unicode strings.  If :attr:`returns_unicode` is :const:`False`, 8-bit
232   strings containing UTF-8 encoded data will be passed to the handlers.  This is
233   :const:`True` by default when Python is built with Unicode support.
234
235   .. versionchanged:: 1.6
236      Can be changed at any time to affect the result type.
237
238
239.. attribute:: xmlparser.specified_attributes
240
241   If set to a non-zero integer, the parser will report only those attributes which
242   were specified in the document instance and not those which were derived from
243   attribute declarations.  Applications which set this need to be especially
244   careful to use what additional information is available from the declarations as
245   needed to comply with the standards for the behavior of XML processors.  By
246   default, this attribute is false; it may be changed at any time.
247
248   .. versionadded:: 2.1
249
250The following attributes contain values relating to the most recent error
251encountered by an :class:`xmlparser` object, and will only have correct values
252once a call to :meth:`Parse` or :meth:`ParseFile` has raised a
253:exc:`xml.parsers.expat.ExpatError` exception.
254
255
256.. attribute:: xmlparser.ErrorByteIndex
257
258   Byte index at which an error occurred.
259
260
261.. attribute:: xmlparser.ErrorCode
262
263   Numeric code specifying the problem.  This value can be passed to the
264   :func:`ErrorString` function, or compared to one of the constants defined in the
265   ``errors`` object.
266
267
268.. attribute:: xmlparser.ErrorColumnNumber
269
270   Column number at which an error occurred.
271
272
273.. attribute:: xmlparser.ErrorLineNumber
274
275   Line number at which an error occurred.
276
277The following attributes contain values relating to the current parse location
278in an :class:`xmlparser` object.  During a callback reporting a parse event they
279indicate the location of the first of the sequence of characters that generated
280the event.  When called outside of a callback, the position indicated will be
281just past the last parse event (regardless of whether there was an associated
282callback).
283
284.. versionadded:: 2.4
285
286
287.. attribute:: xmlparser.CurrentByteIndex
288
289   Current byte index in the parser input.
290
291
292.. attribute:: xmlparser.CurrentColumnNumber
293
294   Current column number in the parser input.
295
296
297.. attribute:: xmlparser.CurrentLineNumber
298
299   Current line number in the parser input.
300
301Here is the list of handlers that can be set.  To set a handler on an
302:class:`xmlparser` object *o*, use ``o.handlername = func``.  *handlername* must
303be taken from the following list, and *func* must be a callable object accepting
304the correct number of arguments.  The arguments are all strings, unless
305otherwise stated.
306
307
308.. method:: xmlparser.XmlDeclHandler(version, encoding, standalone)
309
310   Called when the XML declaration is parsed.  The XML declaration is the
311   (optional) declaration of the applicable version of the XML recommendation, the
312   encoding of the document text, and an optional "standalone" declaration.
313   *version* and *encoding* will be strings of the type dictated by the
314   :attr:`returns_unicode` attribute, and *standalone* will be ``1`` if the
315   document is declared standalone, ``0`` if it is declared not to be standalone,
316   or ``-1`` if the standalone clause was omitted. This is only available with
317   Expat version 1.95.0 or newer.
318
319   .. versionadded:: 2.1
320
321
322.. method:: xmlparser.StartDoctypeDeclHandler(doctypeName, systemId, publicId, has_internal_subset)
323
324   Called when Expat begins parsing the document type declaration (``<!DOCTYPE
325   ...``).  The *doctypeName* is provided exactly as presented.  The *systemId* and
326   *publicId* parameters give the system and public identifiers if specified, or
327   ``None`` if omitted.  *has_internal_subset* will be true if the document
328   contains and internal document declaration subset. This requires Expat version
329   1.2 or newer.
330
331
332.. method:: xmlparser.EndDoctypeDeclHandler()
333
334   Called when Expat is done parsing the document type declaration. This requires
335   Expat version 1.2 or newer.
336
337
338.. method:: xmlparser.ElementDeclHandler(name, model)
339
340   Called once for each element type declaration.  *name* is the name of the
341   element type, and *model* is a representation of the content model.
342
343
344.. method:: xmlparser.AttlistDeclHandler(elname, attname, type, default, required)
345
346   Called for each declared attribute for an element type.  If an attribute list
347   declaration declares three attributes, this handler is called three times, once
348   for each attribute.  *elname* is the name of the element to which the
349   declaration applies and *attname* is the name of the attribute declared.  The
350   attribute type is a string passed as *type*; the possible values are
351   ``'CDATA'``, ``'ID'``, ``'IDREF'``, ... *default* gives the default value for
352   the attribute used when the attribute is not specified by the document instance,
353   or ``None`` if there is no default value (``#IMPLIED`` values).  If the
354   attribute is required to be given in the document instance, *required* will be
355   true. This requires Expat version 1.95.0 or newer.
356
357
358.. method:: xmlparser.StartElementHandler(name, attributes)
359
360   Called for the start of every element.  *name* is a string containing the
361   element name, and *attributes* is a dictionary mapping attribute names to their
362   values.
363
364
365.. method:: xmlparser.EndElementHandler(name)
366
367   Called for the end of every element.
368
369
370.. method:: xmlparser.ProcessingInstructionHandler(target, data)
371
372   Called for every processing instruction.
373
374
375.. method:: xmlparser.CharacterDataHandler(data)
376
377   Called for character data.  This will be called for normal character data, CDATA
378   marked content, and ignorable whitespace.  Applications which must distinguish
379   these cases can use the :attr:`StartCdataSectionHandler`,
380   :attr:`EndCdataSectionHandler`, and :attr:`ElementDeclHandler` callbacks to
381   collect the required information.
382
383
384.. method:: xmlparser.UnparsedEntityDeclHandler(entityName, base, systemId, publicId, notationName)
385
386   Called for unparsed (NDATA) entity declarations.  This is only present for
387   version 1.2 of the Expat library; for more recent versions, use
388   :attr:`EntityDeclHandler` instead.  (The underlying function in the Expat
389   library has been declared obsolete.)
390
391
392.. method:: xmlparser.EntityDeclHandler(entityName, is_parameter_entity, value, base, systemId, publicId, notationName)
393
394   Called for all entity declarations.  For parameter and internal entities,
395   *value* will be a string giving the declared contents of the entity; this will
396   be ``None`` for external entities.  The *notationName* parameter will be
397   ``None`` for parsed entities, and the name of the notation for unparsed
398   entities. *is_parameter_entity* will be true if the entity is a parameter entity
399   or false for general entities (most applications only need to be concerned with
400   general entities). This is only available starting with version 1.95.0 of the
401   Expat library.
402
403   .. versionadded:: 2.1
404
405
406.. method:: xmlparser.NotationDeclHandler(notationName, base, systemId, publicId)
407
408   Called for notation declarations.  *notationName*, *base*, and *systemId*, and
409   *publicId* are strings if given.  If the public identifier is omitted,
410   *publicId* will be ``None``.
411
412
413.. method:: xmlparser.StartNamespaceDeclHandler(prefix, uri)
414
415   Called when an element contains a namespace declaration.  Namespace declarations
416   are processed before the :attr:`StartElementHandler` is called for the element
417   on which declarations are placed.
418
419
420.. method:: xmlparser.EndNamespaceDeclHandler(prefix)
421
422   Called when the closing tag is reached for an element  that contained a
423   namespace declaration.  This is called once for each namespace declaration on
424   the element in the reverse of the order for which the
425   :attr:`StartNamespaceDeclHandler` was called to indicate the start of each
426   namespace declaration's scope.  Calls to this handler are made after the
427   corresponding :attr:`EndElementHandler` for the end of the element.
428
429
430.. method:: xmlparser.CommentHandler(data)
431
432   Called for comments.  *data* is the text of the comment, excluding the leading
433   '``<!-``\ ``-``' and trailing '``-``\ ``->``'.
434
435
436.. method:: xmlparser.StartCdataSectionHandler()
437
438   Called at the start of a CDATA section.  This and :attr:`EndCdataSectionHandler`
439   are needed to be able to identify the syntactical start and end for CDATA
440   sections.
441
442
443.. method:: xmlparser.EndCdataSectionHandler()
444
445   Called at the end of a CDATA section.
446
447
448.. method:: xmlparser.DefaultHandler(data)
449
450   Called for any characters in the XML document for which no applicable handler
451   has been specified.  This means characters that are part of a construct which
452   could be reported, but for which no handler has been supplied.
453
454
455.. method:: xmlparser.DefaultHandlerExpand(data)
456
457   This is the same as the :func:`DefaultHandler`,  but doesn't inhibit expansion
458   of internal entities. The entity reference will not be passed to the default
459   handler.
460
461
462.. method:: xmlparser.NotStandaloneHandler()
463
464   Called if the XML document hasn't been declared as being a standalone document.
465   This happens when there is an external subset or a reference to a parameter
466   entity, but the XML declaration does not set standalone to ``yes`` in an XML
467   declaration.  If this handler returns ``0``, then the parser will throw an
468   :const:`XML_ERROR_NOT_STANDALONE` error.  If this handler is not set, no
469   exception is raised by the parser for this condition.
470
471
472.. method:: xmlparser.ExternalEntityRefHandler(context, base, systemId, publicId)
473
474   Called for references to external entities.  *base* is the current base, as set
475   by a previous call to :meth:`SetBase`.  The public and system identifiers,
476   *systemId* and *publicId*, are strings if given; if the public identifier is not
477   given, *publicId* will be ``None``.  The *context* value is opaque and should
478   only be used as described below.
479
480   For external entities to be parsed, this handler must be implemented. It is
481   responsible for creating the sub-parser using
482   ``ExternalEntityParserCreate(context)``, initializing it with the appropriate
483   callbacks, and parsing the entity.  This handler should return an integer; if it
484   returns ``0``, the parser will throw an
485   :const:`XML_ERROR_EXTERNAL_ENTITY_HANDLING` error, otherwise parsing will
486   continue.
487
488   If this handler is not provided, external entities are reported by the
489   :attr:`DefaultHandler` callback, if provided.
490
491
492.. _expaterror-objects:
493
494ExpatError Exceptions
495---------------------
496
497.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
498
499
500:exc:`ExpatError` exceptions have a number of interesting attributes:
501
502
503.. attribute:: ExpatError.code
504
505   Expat's internal error number for the specific error.  This will match one of
506   the constants defined in the ``errors`` object from this module.
507
508   .. versionadded:: 2.1
509
510
511.. attribute:: ExpatError.lineno
512
513   Line number on which the error was detected.  The first line is numbered ``1``.
514
515   .. versionadded:: 2.1
516
517
518.. attribute:: ExpatError.offset
519
520   Character offset into the line where the error occurred.  The first column is
521   numbered ``0``.
522
523   .. versionadded:: 2.1
524
525
526.. _expat-example:
527
528Example
529-------
530
531The following program defines three handlers that just print out their
532arguments. ::
533
534   import xml.parsers.expat
535
536   # 3 handler functions
537   def start_element(name, attrs):
538       print 'Start element:', name, attrs
539   def end_element(name):
540       print 'End element:', name
541   def char_data(data):
542       print 'Character data:', repr(data)
543
544   p = xml.parsers.expat.ParserCreate()
545
546   p.StartElementHandler = start_element
547   p.EndElementHandler = end_element
548   p.CharacterDataHandler = char_data
549
550   p.Parse("""<?xml version="1.0"?>
551   <parent id="top"><child1 name="paul">Text goes here</child1>
552   <child2 name="fred">More text</child2>
553   </parent>""", 1)
554
555The output from this program is::
556
557   Start element: parent {'id': 'top'}
558   Start element: child1 {'name': 'paul'}
559   Character data: 'Text goes here'
560   End element: child1
561   Character data: '\n'
562   Start element: child2 {'name': 'fred'}
563   Character data: 'More text'
564   End element: child2
565   Character data: '\n'
566   End element: parent
567
568
569.. _expat-content-models:
570
571Content Model Descriptions
572--------------------------
573
574.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
575
576
577Content modules are described using nested tuples.  Each tuple contains four
578values: the type, the quantifier, the name, and a tuple of children.  Children
579are simply additional content module descriptions.
580
581The values of the first two fields are constants defined in the ``model`` object
582of the :mod:`xml.parsers.expat` module.  These constants can be collected in two
583groups: the model type group and the quantifier group.
584
585The constants in the model type group are:
586
587
588.. data:: XML_CTYPE_ANY
589   :noindex:
590
591   The element named by the model name was declared to have a content model of
592   ``ANY``.
593
594
595.. data:: XML_CTYPE_CHOICE
596   :noindex:
597
598   The named element allows a choice from a number of options; this is used for
599   content models such as ``(A | B | C)``.
600
601
602.. data:: XML_CTYPE_EMPTY
603   :noindex:
604
605   Elements which are declared to be ``EMPTY`` have this model type.
606
607
608.. data:: XML_CTYPE_MIXED
609   :noindex:
610
611
612.. data:: XML_CTYPE_NAME
613   :noindex:
614
615
616.. data:: XML_CTYPE_SEQ
617   :noindex:
618
619   Models which represent a series of models which follow one after the other are
620   indicated with this model type.  This is used for models such as ``(A, B, C)``.
621
622The constants in the quantifier group are:
623
624
625.. data:: XML_CQUANT_NONE
626   :noindex:
627
628   No modifier is given, so it can appear exactly once, as for ``A``.
629
630
631.. data:: XML_CQUANT_OPT
632   :noindex:
633
634   The model is optional: it can appear once or not at all, as for ``A?``.
635
636
637.. data:: XML_CQUANT_PLUS
638   :noindex:
639
640   The model must occur one or more times (like ``A+``).
641
642
643.. data:: XML_CQUANT_REP
644   :noindex:
645
646   The model must occur zero or more times, as for ``A*``.
647
648
649.. _expat-errors:
650
651Expat error constants
652---------------------
653
654The following constants are provided in the ``errors`` object of the
655:mod:`xml.parsers.expat` module.  These constants are useful in interpreting
656some of the attributes of the :exc:`ExpatError` exception objects raised when an
657error has occurred.
658
659The ``errors`` object has the following attributes:
660
661
662.. data:: XML_ERROR_ASYNC_ENTITY
663   :noindex:
664
665
666.. data:: XML_ERROR_ATTRIBUTE_EXTERNAL_ENTITY_REF
667   :noindex:
668
669   An entity reference in an attribute value referred to an external entity instead
670   of an internal entity.
671
672
673.. data:: XML_ERROR_BAD_CHAR_REF
674   :noindex:
675
676   A character reference referred to a character which is illegal in XML (for
677   example, character ``0``, or '``&#0;``').
678
679
680.. data:: XML_ERROR_BINARY_ENTITY_REF
681   :noindex:
682
683   An entity reference referred to an entity which was declared with a notation, so
684   cannot be parsed.
685
686
687.. data:: XML_ERROR_DUPLICATE_ATTRIBUTE
688   :noindex:
689
690   An attribute was used more than once in a start tag.
691
692
693.. data:: XML_ERROR_INCORRECT_ENCODING
694   :noindex:
695
696
697.. data:: XML_ERROR_INVALID_TOKEN
698   :noindex:
699
700   Raised when an input byte could not properly be assigned to a character; for
701   example, a NUL byte (value ``0``) in a UTF-8 input stream.
702
703
704.. data:: XML_ERROR_JUNK_AFTER_DOC_ELEMENT
705   :noindex:
706
707   Something other than whitespace occurred after the document element.
708
709
710.. data:: XML_ERROR_MISPLACED_XML_PI
711   :noindex:
712
713   An XML declaration was found somewhere other than the start of the input data.
714
715
716.. data:: XML_ERROR_NO_ELEMENTS
717   :noindex:
718
719   The document contains no elements (XML requires all documents to contain exactly
720   one top-level element)..
721
722
723.. data:: XML_ERROR_NO_MEMORY
724   :noindex:
725
726   Expat was not able to allocate memory internally.
727
728
729.. data:: XML_ERROR_PARAM_ENTITY_REF
730   :noindex:
731
732   A parameter entity reference was found where it was not allowed.
733
734
735.. data:: XML_ERROR_PARTIAL_CHAR
736   :noindex:
737
738   An incomplete character was found in the input.
739
740
741.. data:: XML_ERROR_RECURSIVE_ENTITY_REF
742   :noindex:
743
744   An entity reference contained another reference to the same entity; possibly via
745   a different name, and possibly indirectly.
746
747
748.. data:: XML_ERROR_SYNTAX
749   :noindex:
750
751   Some unspecified syntax error was encountered.
752
753
754.. data:: XML_ERROR_TAG_MISMATCH
755   :noindex:
756
757   An end tag did not match the innermost open start tag.
758
759
760.. data:: XML_ERROR_UNCLOSED_TOKEN
761   :noindex:
762
763   Some token (such as a start tag) was not closed before the end of the stream or
764   the next token was encountered.
765
766
767.. data:: XML_ERROR_UNDEFINED_ENTITY
768   :noindex:
769
770   A reference was made to a entity which was not defined.
771
772
773.. data:: XML_ERROR_UNKNOWN_ENCODING
774   :noindex:
775
776   The document encoding is not supported by Expat.
777
778
779.. data:: XML_ERROR_UNCLOSED_CDATA_SECTION
780   :noindex:
781
782   A CDATA marked section was not closed.
783
784
785.. data:: XML_ERROR_EXTERNAL_ENTITY_HANDLING
786   :noindex:
787
788
789.. data:: XML_ERROR_NOT_STANDALONE
790   :noindex:
791
792   The parser determined that the document was not "standalone" though it declared
793   itself to be in the XML declaration, and the :attr:`NotStandaloneHandler` was
794   set and returned ``0``.
795
796
797.. data:: XML_ERROR_UNEXPECTED_STATE
798   :noindex:
799
800
801.. data:: XML_ERROR_ENTITY_DECLARED_IN_PE
802   :noindex:
803
804
805.. data:: XML_ERROR_FEATURE_REQUIRES_XML_DTD
806   :noindex:
807
808   An operation was requested that requires DTD support to be compiled in, but
809   Expat was configured without DTD support.  This should never be reported by a
810   standard build of the :mod:`xml.parsers.expat` module.
811
812
813.. data:: XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING
814   :noindex:
815
816   A behavioral change was requested after parsing started that can only be changed
817   before parsing has started.  This is (currently) only raised by
818   :meth:`UseForeignDTD`.
819
820
821.. data:: XML_ERROR_UNBOUND_PREFIX
822   :noindex:
823
824   An undeclared prefix was found when namespace processing was enabled.
825
826
827.. data:: XML_ERROR_UNDECLARING_PREFIX
828   :noindex:
829
830   The document attempted to remove the namespace declaration associated with a
831   prefix.
832
833
834.. data:: XML_ERROR_INCOMPLETE_PE
835   :noindex:
836
837   A parameter entity contained incomplete markup.
838
839
840.. data:: XML_ERROR_XML_DECL
841   :noindex:
842
843   The document contained no document element at all.
844
845
846.. data:: XML_ERROR_TEXT_DECL
847   :noindex:
848
849   There was an error parsing a text declaration in an external entity.
850
851
852.. data:: XML_ERROR_PUBLICID
853   :noindex:
854
855   Characters were found in the public id that are not allowed.
856
857
858.. data:: XML_ERROR_SUSPENDED
859   :noindex:
860
861   The requested operation was made on a suspended parser, but isn't allowed.  This
862   includes attempts to provide additional input or to stop the parser.
863
864
865.. data:: XML_ERROR_NOT_SUSPENDED
866   :noindex:
867
868   An attempt to resume the parser was made when the parser had not been suspended.
869
870
871.. data:: XML_ERROR_ABORTED
872   :noindex:
873
874   This should not be reported to Python applications.
875
876
877.. data:: XML_ERROR_FINISHED
878   :noindex:
879
880   The requested operation was made on a parser which was finished parsing input,
881   but isn't allowed.  This includes attempts to provide additional input or to
882   stop the parser.
883
884
885.. data:: XML_ERROR_SUSPEND_PE
886   :noindex:
887
888
889.. rubric:: Footnotes
890
891.. [#] The encoding string included in XML output should conform to the
892   appropriate standards. For example, "UTF-8" is valid, but "UTF8" is
893   not. See http://www.w3.org/TR/2006/REC-xml11-20060816/#NT-EncodingDecl
894   and http://www.iana.org/assignments/character-sets .
895