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1:mod:`xml.parsers.expat` --- Fast XML parsing using Expat
2=========================================================
3
4.. module:: xml.parsers.expat
5   :synopsis: An interface to the Expat non-validating XML parser.
6
7.. moduleauthor:: Paul Prescod <paul@prescod.net>
8
9--------------
10
11.. Markup notes:
12
13   Many of the attributes of the XMLParser objects are callbacks.  Since
14   signature information must be presented, these are described using the method
15   directive.  Since they are attributes which are set by client code, in-text
16   references to these attributes should be marked using the :member: role.
17
18
19.. warning::
20
21   The :mod:`pyexpat` module is not secure against maliciously
22   constructed data.  If you need to parse untrusted or unauthenticated data see
23   :ref:`xml-vulnerabilities`.
24
25
26.. index:: single: Expat
27
28The :mod:`xml.parsers.expat` module is a Python interface to the Expat
29non-validating XML parser. The module provides a single extension type,
30:class:`xmlparser`, that represents the current state of an XML parser.  After
31an :class:`xmlparser` object has been created, various attributes of the object
32can be set to handler functions.  When an XML document is then fed to the
33parser, the handler functions are called for the character data and markup in
34the XML document.
35
36.. index:: module: pyexpat
37
38This module uses the :mod:`pyexpat` module to provide access to the Expat
39parser.  Direct use of the :mod:`pyexpat` module is deprecated.
40
41This module provides one exception and one type object:
42
43
44.. exception:: ExpatError
45
46   The exception raised when Expat reports an error.  See section
47   :ref:`expaterror-objects` for more information on interpreting Expat errors.
48
49
50.. exception:: error
51
52   Alias for :exc:`ExpatError`.
53
54
55.. data:: XMLParserType
56
57   The type of the return values from the :func:`ParserCreate` function.
58
59The :mod:`xml.parsers.expat` module contains two functions:
60
61
62.. function:: ErrorString(errno)
63
64   Returns an explanatory string for a given error number *errno*.
65
66
67.. function:: ParserCreate(encoding=None, namespace_separator=None)
68
69   Creates and returns a new :class:`xmlparser` object.   *encoding*, if specified,
70   must be a string naming the encoding  used by the XML data.  Expat doesn't
71   support as many encodings as Python does, and its repertoire of encodings can't
72   be extended; it supports UTF-8, UTF-16, ISO-8859-1 (Latin1), and ASCII.  If
73   *encoding* [1]_ is given it will override the implicit or explicit encoding of the
74   document.
75
76   Expat can optionally do XML namespace processing for you, enabled by providing a
77   value for *namespace_separator*.  The value must be a one-character string; a
78   :exc:`ValueError` will be raised if the string has an illegal length (``None``
79   is considered the same as omission).  When namespace processing is enabled,
80   element type names and attribute names that belong to a namespace will be
81   expanded.  The element name passed to the element handlers
82   :attr:`StartElementHandler` and :attr:`EndElementHandler` will be the
83   concatenation of the namespace URI, the namespace separator character, and the
84   local part of the name.  If the namespace separator is a zero byte (``chr(0)``)
85   then the namespace URI and the local part will be concatenated without any
86   separator.
87
88   For example, if *namespace_separator* is set to a space character (``' '``) and
89   the following document is parsed:
90
91   .. code-block:: xml
92
93      <?xml version="1.0"?>
94      <root xmlns    = "http://default-namespace.org/"
95            xmlns:py = "http://www.python.org/ns/">
96        <py:elem1 />
97        <elem2 xmlns="" />
98      </root>
99
100   :attr:`StartElementHandler` will receive the following strings for each
101   element::
102
103      http://default-namespace.org/ root
104      http://www.python.org/ns/ elem1
105      elem2
106
107   Due to limitations in the ``Expat`` library used by :mod:`pyexpat`,
108   the :class:`xmlparser` instance returned can only be used to parse a single
109   XML document.  Call ``ParserCreate`` for each document to provide unique
110   parser instances.
111
112
113.. seealso::
114
115   `The Expat XML Parser <http://www.libexpat.org/>`_
116      Home page of the Expat project.
117
118
119.. _xmlparser-objects:
120
121XMLParser Objects
122-----------------
123
124:class:`xmlparser` objects have the following methods:
125
126
127.. method:: xmlparser.Parse(data[, isfinal])
128
129   Parses the contents of the string *data*, calling the appropriate handler
130   functions to process the parsed data.  *isfinal* must be true on the final call
131   to this method; it allows the parsing of a single file in fragments,
132   not the submission of multiple files.
133   *data* can be the empty string at any time.
134
135
136.. method:: xmlparser.ParseFile(file)
137
138   Parse XML data reading from the object *file*.  *file* only needs to provide
139   the ``read(nbytes)`` method, returning the empty string when there's no more
140   data.
141
142
143.. method:: xmlparser.SetBase(base)
144
145   Sets the base to be used for resolving relative URIs in system identifiers in
146   declarations.  Resolving relative identifiers is left to the application: this
147   value will be passed through as the *base* argument to the
148   :func:`ExternalEntityRefHandler`, :func:`NotationDeclHandler`, and
149   :func:`UnparsedEntityDeclHandler` functions.
150
151
152.. method:: xmlparser.GetBase()
153
154   Returns a string containing the base set by a previous call to :meth:`SetBase`,
155   or ``None`` if  :meth:`SetBase` hasn't been called.
156
157
158.. method:: xmlparser.GetInputContext()
159
160   Returns the input data that generated the current event as a string. The data is
161   in the encoding of the entity which contains the text. When called while an
162   event handler is not active, the return value is ``None``.
163
164
165.. method:: xmlparser.ExternalEntityParserCreate(context[, encoding])
166
167   Create a "child" parser which can be used to parse an external parsed entity
168   referred to by content parsed by the parent parser.  The *context* parameter
169   should be the string passed to the :meth:`ExternalEntityRefHandler` handler
170   function, described below. The child parser is created with the
171   :attr:`ordered_attributes` and :attr:`specified_attributes` set to the values of
172   this parser.
173
174.. method:: xmlparser.SetParamEntityParsing(flag)
175
176   Control parsing of parameter entities (including the external DTD subset).
177   Possible *flag* values are :const:`XML_PARAM_ENTITY_PARSING_NEVER`,
178   :const:`XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE` and
179   :const:`XML_PARAM_ENTITY_PARSING_ALWAYS`.  Return true if setting the flag
180   was successful.
181
182.. method:: xmlparser.UseForeignDTD([flag])
183
184   Calling this with a true value for *flag* (the default) will cause Expat to call
185   the :attr:`ExternalEntityRefHandler` with :const:`None` for all arguments to
186   allow an alternate DTD to be loaded.  If the document does not contain a
187   document type declaration, the :attr:`ExternalEntityRefHandler` will still be
188   called, but the :attr:`StartDoctypeDeclHandler` and
189   :attr:`EndDoctypeDeclHandler` will not be called.
190
191   Passing a false value for *flag* will cancel a previous call that passed a true
192   value, but otherwise has no effect.
193
194   This method can only be called before the :meth:`Parse` or :meth:`ParseFile`
195   methods are called; calling it after either of those have been called causes
196   :exc:`ExpatError` to be raised with the :attr:`code` attribute set to
197   ``errors.codes[errors.XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING]``.
198
199:class:`xmlparser` objects have the following attributes:
200
201
202.. attribute:: xmlparser.buffer_size
203
204   The size of the buffer used when :attr:`buffer_text` is true.
205   A new buffer size can be set by assigning a new integer value
206   to this attribute.
207   When the size is changed, the buffer will be flushed.
208
209
210.. attribute:: xmlparser.buffer_text
211
212   Setting this to true causes the :class:`xmlparser` object to buffer textual
213   content returned by Expat to avoid multiple calls to the
214   :meth:`CharacterDataHandler` callback whenever possible.  This can improve
215   performance substantially since Expat normally breaks character data into chunks
216   at every line ending.  This attribute is false by default, and may be changed at
217   any time.
218
219
220.. attribute:: xmlparser.buffer_used
221
222   If :attr:`buffer_text` is enabled, the number of bytes stored in the buffer.
223   These bytes represent UTF-8 encoded text.  This attribute has no meaningful
224   interpretation when :attr:`buffer_text` is false.
225
226
227.. attribute:: xmlparser.ordered_attributes
228
229   Setting this attribute to a non-zero integer causes the attributes to be
230   reported as a list rather than a dictionary.  The attributes are presented in
231   the order found in the document text.  For each attribute, two list entries are
232   presented: the attribute name and the attribute value.  (Older versions of this
233   module also used this format.)  By default, this attribute is false; it may be
234   changed at any time.
235
236
237.. attribute:: xmlparser.specified_attributes
238
239   If set to a non-zero integer, the parser will report only those attributes which
240   were specified in the document instance and not those which were derived from
241   attribute declarations.  Applications which set this need to be especially
242   careful to use what additional information is available from the declarations as
243   needed to comply with the standards for the behavior of XML processors.  By
244   default, this attribute is false; it may be changed at any time.
245
246
247The following attributes contain values relating to the most recent error
248encountered by an :class:`xmlparser` object, and will only have correct values
249once a call to :meth:`Parse` or :meth:`ParseFile` has raised an
250:exc:`xml.parsers.expat.ExpatError` exception.
251
252
253.. attribute:: xmlparser.ErrorByteIndex
254
255   Byte index at which an error occurred.
256
257
258.. attribute:: xmlparser.ErrorCode
259
260   Numeric code specifying the problem.  This value can be passed to the
261   :func:`ErrorString` function, or compared to one of the constants defined in the
262   ``errors`` object.
263
264
265.. attribute:: xmlparser.ErrorColumnNumber
266
267   Column number at which an error occurred.
268
269
270.. attribute:: xmlparser.ErrorLineNumber
271
272   Line number at which an error occurred.
273
274The following attributes contain values relating to the current parse location
275in an :class:`xmlparser` object.  During a callback reporting a parse event they
276indicate the location of the first of the sequence of characters that generated
277the event.  When called outside of a callback, the position indicated will be
278just past the last parse event (regardless of whether there was an associated
279callback).
280
281
282.. attribute:: xmlparser.CurrentByteIndex
283
284   Current byte index in the parser input.
285
286
287.. attribute:: xmlparser.CurrentColumnNumber
288
289   Current column number in the parser input.
290
291
292.. attribute:: xmlparser.CurrentLineNumber
293
294   Current line number in the parser input.
295
296Here is the list of handlers that can be set.  To set a handler on an
297:class:`xmlparser` object *o*, use ``o.handlername = func``.  *handlername* must
298be taken from the following list, and *func* must be a callable object accepting
299the correct number of arguments.  The arguments are all strings, unless
300otherwise stated.
301
302
303.. method:: xmlparser.XmlDeclHandler(version, encoding, standalone)
304
305   Called when the XML declaration is parsed.  The XML declaration is the
306   (optional) declaration of the applicable version of the XML recommendation, the
307   encoding of the document text, and an optional "standalone" declaration.
308   *version* and *encoding* will be strings, and *standalone* will be ``1`` if the
309   document is declared standalone, ``0`` if it is declared not to be standalone,
310   or ``-1`` if the standalone clause was omitted. This is only available with
311   Expat version 1.95.0 or newer.
312
313
314.. method:: xmlparser.StartDoctypeDeclHandler(doctypeName, systemId, publicId, has_internal_subset)
315
316   Called when Expat begins parsing the document type declaration (``<!DOCTYPE
317   ...``).  The *doctypeName* is provided exactly as presented.  The *systemId* and
318   *publicId* parameters give the system and public identifiers if specified, or
319   ``None`` if omitted.  *has_internal_subset* will be true if the document
320   contains and internal document declaration subset. This requires Expat version
321   1.2 or newer.
322
323
324.. method:: xmlparser.EndDoctypeDeclHandler()
325
326   Called when Expat is done parsing the document type declaration. This requires
327   Expat version 1.2 or newer.
328
329
330.. method:: xmlparser.ElementDeclHandler(name, model)
331
332   Called once for each element type declaration.  *name* is the name of the
333   element type, and *model* is a representation of the content model.
334
335
336.. method:: xmlparser.AttlistDeclHandler(elname, attname, type, default, required)
337
338   Called for each declared attribute for an element type.  If an attribute list
339   declaration declares three attributes, this handler is called three times, once
340   for each attribute.  *elname* is the name of the element to which the
341   declaration applies and *attname* is the name of the attribute declared.  The
342   attribute type is a string passed as *type*; the possible values are
343   ``'CDATA'``, ``'ID'``, ``'IDREF'``, ... *default* gives the default value for
344   the attribute used when the attribute is not specified by the document instance,
345   or ``None`` if there is no default value (``#IMPLIED`` values).  If the
346   attribute is required to be given in the document instance, *required* will be
347   true. This requires Expat version 1.95.0 or newer.
348
349
350.. method:: xmlparser.StartElementHandler(name, attributes)
351
352   Called for the start of every element.  *name* is a string containing the
353   element name, and *attributes* is the element attributes. If
354   :attr:`ordered_attributes` is true, this is a list (see
355   :attr:`ordered_attributes` for a full description). Otherwise it's a
356   dictionary mapping names to values.
357
358
359.. method:: xmlparser.EndElementHandler(name)
360
361   Called for the end of every element.
362
363
364.. method:: xmlparser.ProcessingInstructionHandler(target, data)
365
366   Called for every processing instruction.
367
368
369.. method:: xmlparser.CharacterDataHandler(data)
370
371   Called for character data.  This will be called for normal character data, CDATA
372   marked content, and ignorable whitespace.  Applications which must distinguish
373   these cases can use the :attr:`StartCdataSectionHandler`,
374   :attr:`EndCdataSectionHandler`, and :attr:`ElementDeclHandler` callbacks to
375   collect the required information.
376
377
378.. method:: xmlparser.UnparsedEntityDeclHandler(entityName, base, systemId, publicId, notationName)
379
380   Called for unparsed (NDATA) entity declarations.  This is only present for
381   version 1.2 of the Expat library; for more recent versions, use
382   :attr:`EntityDeclHandler` instead.  (The underlying function in the Expat
383   library has been declared obsolete.)
384
385
386.. method:: xmlparser.EntityDeclHandler(entityName, is_parameter_entity, value, base, systemId, publicId, notationName)
387
388   Called for all entity declarations.  For parameter and internal entities,
389   *value* will be a string giving the declared contents of the entity; this will
390   be ``None`` for external entities.  The *notationName* parameter will be
391   ``None`` for parsed entities, and the name of the notation for unparsed
392   entities. *is_parameter_entity* will be true if the entity is a parameter entity
393   or false for general entities (most applications only need to be concerned with
394   general entities). This is only available starting with version 1.95.0 of the
395   Expat library.
396
397
398.. method:: xmlparser.NotationDeclHandler(notationName, base, systemId, publicId)
399
400   Called for notation declarations.  *notationName*, *base*, and *systemId*, and
401   *publicId* are strings if given.  If the public identifier is omitted,
402   *publicId* will be ``None``.
403
404
405.. method:: xmlparser.StartNamespaceDeclHandler(prefix, uri)
406
407   Called when an element contains a namespace declaration.  Namespace declarations
408   are processed before the :attr:`StartElementHandler` is called for the element
409   on which declarations are placed.
410
411
412.. method:: xmlparser.EndNamespaceDeclHandler(prefix)
413
414   Called when the closing tag is reached for an element  that contained a
415   namespace declaration.  This is called once for each namespace declaration on
416   the element in the reverse of the order for which the
417   :attr:`StartNamespaceDeclHandler` was called to indicate the start of each
418   namespace declaration's scope.  Calls to this handler are made after the
419   corresponding :attr:`EndElementHandler` for the end of the element.
420
421
422.. method:: xmlparser.CommentHandler(data)
423
424   Called for comments.  *data* is the text of the comment, excluding the leading
425   ``'<!-``\ ``-'`` and trailing ``'-``\ ``->'``.
426
427
428.. method:: xmlparser.StartCdataSectionHandler()
429
430   Called at the start of a CDATA section.  This and :attr:`EndCdataSectionHandler`
431   are needed to be able to identify the syntactical start and end for CDATA
432   sections.
433
434
435.. method:: xmlparser.EndCdataSectionHandler()
436
437   Called at the end of a CDATA section.
438
439
440.. method:: xmlparser.DefaultHandler(data)
441
442   Called for any characters in the XML document for which no applicable handler
443   has been specified.  This means characters that are part of a construct which
444   could be reported, but for which no handler has been supplied.
445
446
447.. method:: xmlparser.DefaultHandlerExpand(data)
448
449   This is the same as the :func:`DefaultHandler`,  but doesn't inhibit expansion
450   of internal entities. The entity reference will not be passed to the default
451   handler.
452
453
454.. method:: xmlparser.NotStandaloneHandler()
455
456   Called if the XML document hasn't been declared as being a standalone document.
457   This happens when there is an external subset or a reference to a parameter
458   entity, but the XML declaration does not set standalone to ``yes`` in an XML
459   declaration.  If this handler returns ``0``, then the parser will raise an
460   :const:`XML_ERROR_NOT_STANDALONE` error.  If this handler is not set, no
461   exception is raised by the parser for this condition.
462
463
464.. method:: xmlparser.ExternalEntityRefHandler(context, base, systemId, publicId)
465
466   Called for references to external entities.  *base* is the current base, as set
467   by a previous call to :meth:`SetBase`.  The public and system identifiers,
468   *systemId* and *publicId*, are strings if given; if the public identifier is not
469   given, *publicId* will be ``None``.  The *context* value is opaque and should
470   only be used as described below.
471
472   For external entities to be parsed, this handler must be implemented. It is
473   responsible for creating the sub-parser using
474   ``ExternalEntityParserCreate(context)``, initializing it with the appropriate
475   callbacks, and parsing the entity.  This handler should return an integer; if it
476   returns ``0``, the parser will raise an
477   :const:`XML_ERROR_EXTERNAL_ENTITY_HANDLING` error, otherwise parsing will
478   continue.
479
480   If this handler is not provided, external entities are reported by the
481   :attr:`DefaultHandler` callback, if provided.
482
483
484.. _expaterror-objects:
485
486ExpatError Exceptions
487---------------------
488
489.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
490
491
492:exc:`ExpatError` exceptions have a number of interesting attributes:
493
494
495.. attribute:: ExpatError.code
496
497   Expat's internal error number for the specific error.  The
498   :data:`errors.messages <xml.parsers.expat.errors.messages>` dictionary maps
499   these error numbers to Expat's error messages.  For example::
500
501      from xml.parsers.expat import ParserCreate, ExpatError, errors
502
503      p = ParserCreate()
504      try:
505          p.Parse(some_xml_document)
506      except ExpatError as err:
507          print("Error:", errors.messages[err.code])
508
509   The :mod:`~xml.parsers.expat.errors` module also provides error message
510   constants and a dictionary :data:`~xml.parsers.expat.errors.codes` mapping
511   these messages back to the error codes, see below.
512
513
514.. attribute:: ExpatError.lineno
515
516   Line number on which the error was detected.  The first line is numbered ``1``.
517
518
519.. attribute:: ExpatError.offset
520
521   Character offset into the line where the error occurred.  The first column is
522   numbered ``0``.
523
524
525.. _expat-example:
526
527Example
528-------
529
530The following program defines three handlers that just print out their
531arguments. ::
532
533   import xml.parsers.expat
534
535   # 3 handler functions
536   def start_element(name, attrs):
537       print('Start element:', name, attrs)
538   def end_element(name):
539       print('End element:', name)
540   def char_data(data):
541       print('Character data:', repr(data))
542
543   p = xml.parsers.expat.ParserCreate()
544
545   p.StartElementHandler = start_element
546   p.EndElementHandler = end_element
547   p.CharacterDataHandler = char_data
548
549   p.Parse("""<?xml version="1.0"?>
550   <parent id="top"><child1 name="paul">Text goes here</child1>
551   <child2 name="fred">More text</child2>
552   </parent>""", 1)
553
554The output from this program is::
555
556   Start element: parent {'id': 'top'}
557   Start element: child1 {'name': 'paul'}
558   Character data: 'Text goes here'
559   End element: child1
560   Character data: '\n'
561   Start element: child2 {'name': 'fred'}
562   Character data: 'More text'
563   End element: child2
564   Character data: '\n'
565   End element: parent
566
567
568.. _expat-content-models:
569
570Content Model Descriptions
571--------------------------
572
573.. module:: xml.parsers.expat.model
574
575.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
576
577Content models 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 model descriptions.
580
581The values of the first two fields are constants defined in the
582:mod:`xml.parsers.expat.model` 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
654.. module:: xml.parsers.expat.errors
655
656The following constants are provided in the :mod:`xml.parsers.expat.errors`
657module.  These constants are useful in interpreting some of the attributes of
658the :exc:`ExpatError` exception objects raised when an error has occurred.
659Since for backwards compatibility reasons, the constants' value is the error
660*message* and not the numeric error *code*, you do this by comparing its
661:attr:`code` attribute with
662:samp:`errors.codes[errors.XML_ERROR_{CONSTANT_NAME}]`.
663
664The ``errors`` module has the following attributes:
665
666.. data:: codes
667
668   A dictionary mapping numeric error codes to their string descriptions.
669
670   .. versionadded:: 3.2
671
672
673.. data:: messages
674
675   A dictionary mapping string descriptions to their error codes.
676
677   .. versionadded:: 3.2
678
679
680.. data:: XML_ERROR_ASYNC_ENTITY
681
682
683.. data:: XML_ERROR_ATTRIBUTE_EXTERNAL_ENTITY_REF
684
685   An entity reference in an attribute value referred to an external entity instead
686   of an internal entity.
687
688
689.. data:: XML_ERROR_BAD_CHAR_REF
690
691   A character reference referred to a character which is illegal in XML (for
692   example, character ``0``, or '``&#0;``').
693
694
695.. data:: XML_ERROR_BINARY_ENTITY_REF
696
697   An entity reference referred to an entity which was declared with a notation, so
698   cannot be parsed.
699
700
701.. data:: XML_ERROR_DUPLICATE_ATTRIBUTE
702
703   An attribute was used more than once in a start tag.
704
705
706.. data:: XML_ERROR_INCORRECT_ENCODING
707
708
709.. data:: XML_ERROR_INVALID_TOKEN
710
711   Raised when an input byte could not properly be assigned to a character; for
712   example, a NUL byte (value ``0``) in a UTF-8 input stream.
713
714
715.. data:: XML_ERROR_JUNK_AFTER_DOC_ELEMENT
716
717   Something other than whitespace occurred after the document element.
718
719
720.. data:: XML_ERROR_MISPLACED_XML_PI
721
722   An XML declaration was found somewhere other than the start of the input data.
723
724
725.. data:: XML_ERROR_NO_ELEMENTS
726
727   The document contains no elements (XML requires all documents to contain exactly
728   one top-level element)..
729
730
731.. data:: XML_ERROR_NO_MEMORY
732
733   Expat was not able to allocate memory internally.
734
735
736.. data:: XML_ERROR_PARAM_ENTITY_REF
737
738   A parameter entity reference was found where it was not allowed.
739
740
741.. data:: XML_ERROR_PARTIAL_CHAR
742
743   An incomplete character was found in the input.
744
745
746.. data:: XML_ERROR_RECURSIVE_ENTITY_REF
747
748   An entity reference contained another reference to the same entity; possibly via
749   a different name, and possibly indirectly.
750
751
752.. data:: XML_ERROR_SYNTAX
753
754   Some unspecified syntax error was encountered.
755
756
757.. data:: XML_ERROR_TAG_MISMATCH
758
759   An end tag did not match the innermost open start tag.
760
761
762.. data:: XML_ERROR_UNCLOSED_TOKEN
763
764   Some token (such as a start tag) was not closed before the end of the stream or
765   the next token was encountered.
766
767
768.. data:: XML_ERROR_UNDEFINED_ENTITY
769
770   A reference was made to an entity which was not defined.
771
772
773.. data:: XML_ERROR_UNKNOWN_ENCODING
774
775   The document encoding is not supported by Expat.
776
777
778.. data:: XML_ERROR_UNCLOSED_CDATA_SECTION
779
780   A CDATA marked section was not closed.
781
782
783.. data:: XML_ERROR_EXTERNAL_ENTITY_HANDLING
784
785
786.. data:: XML_ERROR_NOT_STANDALONE
787
788   The parser determined that the document was not "standalone" though it declared
789   itself to be in the XML declaration, and the :attr:`NotStandaloneHandler` was
790   set and returned ``0``.
791
792
793.. data:: XML_ERROR_UNEXPECTED_STATE
794
795
796.. data:: XML_ERROR_ENTITY_DECLARED_IN_PE
797
798
799.. data:: XML_ERROR_FEATURE_REQUIRES_XML_DTD
800
801   An operation was requested that requires DTD support to be compiled in, but
802   Expat was configured without DTD support.  This should never be reported by a
803   standard build of the :mod:`xml.parsers.expat` module.
804
805
806.. data:: XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING
807
808   A behavioral change was requested after parsing started that can only be changed
809   before parsing has started.  This is (currently) only raised by
810   :meth:`UseForeignDTD`.
811
812
813.. data:: XML_ERROR_UNBOUND_PREFIX
814
815   An undeclared prefix was found when namespace processing was enabled.
816
817
818.. data:: XML_ERROR_UNDECLARING_PREFIX
819
820   The document attempted to remove the namespace declaration associated with a
821   prefix.
822
823
824.. data:: XML_ERROR_INCOMPLETE_PE
825
826   A parameter entity contained incomplete markup.
827
828
829.. data:: XML_ERROR_XML_DECL
830
831   The document contained no document element at all.
832
833
834.. data:: XML_ERROR_TEXT_DECL
835
836   There was an error parsing a text declaration in an external entity.
837
838
839.. data:: XML_ERROR_PUBLICID
840
841   Characters were found in the public id that are not allowed.
842
843
844.. data:: XML_ERROR_SUSPENDED
845
846   The requested operation was made on a suspended parser, but isn't allowed.  This
847   includes attempts to provide additional input or to stop the parser.
848
849
850.. data:: XML_ERROR_NOT_SUSPENDED
851
852   An attempt to resume the parser was made when the parser had not been suspended.
853
854
855.. data:: XML_ERROR_ABORTED
856
857   This should not be reported to Python applications.
858
859
860.. data:: XML_ERROR_FINISHED
861
862   The requested operation was made on a parser which was finished parsing input,
863   but isn't allowed.  This includes attempts to provide additional input or to
864   stop the parser.
865
866
867.. data:: XML_ERROR_SUSPEND_PE
868
869
870.. rubric:: Footnotes
871
872.. [#] The encoding string included in XML output should conform to the
873   appropriate standards. For example, "UTF-8" is valid, but "UTF8" is
874   not. See https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-EncodingDecl
875   and https://www.iana.org/assignments/character-sets/character-sets.xhtml.
876
877