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Fred Drake7fbc85c2000-09-23 04:47:56 +00001\section{\module{xml.parsers.expat} ---
Fred Drakeefffe8e2000-10-29 05:10:30 +00002 Fast XML parsing using Expat}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +00003
Fred Drake5ed1dac2001-02-08 15:40:33 +00004% Markup notes:
5%
6% Many of the attributes of the XMLParser objects are callbacks.
7% Since signature information must be presented, these are described
8% using the methoddesc environment. Since they are attributes which
9% are set by client code, in-text references to these attributes
10% should be marked using the \member macro and should not include the
11% parentheses used when marking functions and methods.
12
Fred Drake7fbc85c2000-09-23 04:47:56 +000013\declaremodule{standard}{xml.parsers.expat}
14\modulesynopsis{An interface to the Expat non-validating XML parser.}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000015\moduleauthor{Paul Prescod}{paul@prescod.net}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000016
Fred Drake7fbc85c2000-09-23 04:47:56 +000017\versionadded{2.0}
18
Fred Drakeefffe8e2000-10-29 05:10:30 +000019The \module{xml.parsers.expat} module is a Python interface to the
20Expat\index{Expat} non-validating XML parser.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000021The module provides a single extension type, \class{xmlparser}, that
22represents the current state of an XML parser. After an
23\class{xmlparser} object has been created, various attributes of the object
24can be set to handler functions. When an XML document is then fed to
25the parser, the handler functions are called for the character data
26and markup in the XML document.
Fred Drake7fbc85c2000-09-23 04:47:56 +000027
28This module uses the \module{pyexpat}\refbimodindex{pyexpat} module to
29provide access to the Expat parser. Direct use of the
30\module{pyexpat} module is deprecated.
Fred Drakeefffe8e2000-10-29 05:10:30 +000031
32This module provides one exception and one type object:
33
Fred Drake1d8ad2b2001-02-14 18:54:32 +000034\begin{excdesc}{ExpatError}
Fred Drakee0af35e2001-09-20 20:43:28 +000035 The exception raised when Expat reports an error. See section
36 \ref{expaterror-objects}, ``ExpatError Exceptions,'' for more
37 information on interpreting Expat errors.
Fred Drakeefffe8e2000-10-29 05:10:30 +000038\end{excdesc}
39
Fred Drake1d8ad2b2001-02-14 18:54:32 +000040\begin{excdesc}{error}
41 Alias for \exception{ExpatError}.
42\end{excdesc}
43
Fred Drakeefffe8e2000-10-29 05:10:30 +000044\begin{datadesc}{XMLParserType}
45 The type of the return values from the \function{ParserCreate()}
46 function.
47\end{datadesc}
48
49
Fred Drake7fbc85c2000-09-23 04:47:56 +000050The \module{xml.parsers.expat} module contains two functions:
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000051
52\begin{funcdesc}{ErrorString}{errno}
53Returns an explanatory string for a given error number \var{errno}.
54\end{funcdesc}
55
Fred Drakeefffe8e2000-10-29 05:10:30 +000056\begin{funcdesc}{ParserCreate}{\optional{encoding\optional{,
57 namespace_separator}}}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000058Creates and returns a new \class{xmlparser} object.
59\var{encoding}, if specified, must be a string naming the encoding
60used by the XML data. Expat doesn't support as many encodings as
61Python does, and its repertoire of encodings can't be extended; it
Fred Drake5ed1dac2001-02-08 15:40:33 +000062supports UTF-8, UTF-16, ISO-8859-1 (Latin1), and ASCII. If
63\var{encoding} is given it will override the implicit or explicit
64encoding of the document.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000065
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000066Expat can optionally do XML namespace processing for you, enabled by
Fred Drakeefffe8e2000-10-29 05:10:30 +000067providing a value for \var{namespace_separator}. The value must be a
68one-character string; a \exception{ValueError} will be raised if the
69string has an illegal length (\code{None} is considered the same as
70omission). When namespace processing is enabled, element type names
71and attribute names that belong to a namespace will be expanded. The
72element name passed to the element handlers
Fred Drake5ed1dac2001-02-08 15:40:33 +000073\member{StartElementHandler} and \member{EndElementHandler}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000074will be the concatenation of the namespace URI, the namespace
75separator character, and the local part of the name. If the namespace
Fred Drakeefffe8e2000-10-29 05:10:30 +000076separator is a zero byte (\code{chr(0)}) then the namespace URI and
Fred Drake5ed1dac2001-02-08 15:40:33 +000077the local part will be concatenated without any separator.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000078
Fred Drake2fef3ab2000-11-28 06:38:22 +000079For example, if \var{namespace_separator} is set to a space character
80(\character{ }) and the following document is parsed:
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000081
82\begin{verbatim}
83<?xml version="1.0"?>
84<root xmlns = "http://default-namespace.org/"
85 xmlns:py = "http://www.python.org/ns/">
86 <py:elem1 />
87 <elem2 xmlns="" />
88</root>
89\end{verbatim}
90
Fred Drake5ed1dac2001-02-08 15:40:33 +000091\member{StartElementHandler} will receive the following strings
Fred Draked79c33a2000-09-25 14:14:30 +000092for each element:
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000093
94\begin{verbatim}
95http://default-namespace.org/ root
96http://www.python.org/ns/ elem1
97elem2
98\end{verbatim}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +000099\end{funcdesc}
100
Fred Drakef08cbb12000-12-23 22:19:05 +0000101
Fred Drakedce695aa2002-06-20 21:06:03 +0000102\begin{seealso}
103 \seetitle[http://www.libexpat.org/]{The Expat XML Parser}
104 {Home page of the Expat project.}
105\end{seealso}
106
107
Fred Drakef08cbb12000-12-23 22:19:05 +0000108\subsection{XMLParser Objects \label{xmlparser-objects}}
109
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000110\class{xmlparser} objects have the following methods:
111
Fred Drake2fef3ab2000-11-28 06:38:22 +0000112\begin{methoddesc}[xmlparser]{Parse}{data\optional{, isfinal}}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000113Parses the contents of the string \var{data}, calling the appropriate
114handler functions to process the parsed data. \var{isfinal} must be
Fred Drakef08cbb12000-12-23 22:19:05 +0000115true on the final call to this method. \var{data} can be the empty
Fred Drakec05cbb02000-07-05 02:03:34 +0000116string at any time.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000117\end{methoddesc}
118
Fred Drakeefffe8e2000-10-29 05:10:30 +0000119\begin{methoddesc}[xmlparser]{ParseFile}{file}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000120Parse XML data reading from the object \var{file}. \var{file} only
121needs to provide the \method{read(\var{nbytes})} method, returning the
122empty string when there's no more data.
123\end{methoddesc}
124
Fred Drakeefffe8e2000-10-29 05:10:30 +0000125\begin{methoddesc}[xmlparser]{SetBase}{base}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000126Sets the base to be used for resolving relative URIs in system
127identifiers in declarations. Resolving relative identifiers is left
128to the application: this value will be passed through as the
129\var{base} argument to the \function{ExternalEntityRefHandler},
130\function{NotationDeclHandler}, and
131\function{UnparsedEntityDeclHandler} functions.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000132\end{methoddesc}
133
Fred Drakeefffe8e2000-10-29 05:10:30 +0000134\begin{methoddesc}[xmlparser]{GetBase}{}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000135Returns a string containing the base set by a previous call to
136\method{SetBase()}, or \code{None} if
137\method{SetBase()} hasn't been called.
138\end{methoddesc}
139
Fred Drake1d8ad2b2001-02-14 18:54:32 +0000140\begin{methoddesc}[xmlparser]{GetInputContext}{}
141Returns the input data that generated the current event as a string.
142The data is in the encoding of the entity which contains the text.
143When called while an event handler is not active, the return value is
144\code{None}.
145\versionadded{2.1}
146\end{methoddesc}
147
Fred Drakef08cbb12000-12-23 22:19:05 +0000148\begin{methoddesc}[xmlparser]{ExternalEntityParserCreate}{context\optional{,
149 encoding}}
150Create a ``child'' parser which can be used to parse an external
151parsed entity referred to by content parsed by the parent parser. The
Fred Drakeb162d182001-01-04 05:48:08 +0000152\var{context} parameter should be the string passed to the
Fred Drakef08cbb12000-12-23 22:19:05 +0000153\method{ExternalEntityRefHandler()} handler function, described below.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000154The child parser is created with the \member{ordered_attributes},
155\member{returns_unicode} and \member{specified_attributes} set to the
156values of this parser.
Fred Drakef08cbb12000-12-23 22:19:05 +0000157\end{methoddesc}
158
Fred Draked62d5072004-08-10 17:18:32 +0000159\begin{methoddesc}[xmlparser]{UseForeignDTD}{\optional{flag}}
160Calling this with a true value for \var{flag} (the default) will cause
161Expat to call the \member{ExternalEntityRefHandler} with
162\constant{None} for all arguments to allow an alternate DTD to be
163loaded. If the document does not contain a document type declaration,
164the \member{ExternalEntityRefHandler} will still be called, but the
165\member{StartDoctypeDeclHandler} and \member{EndDoctypeDeclHandler}
166will not be called.
167
168Passing a false value for \var{flag} will cancel a previous call that
169passed a true value, but otherwise has no effect.
170
171This method can only be called before the \method{Parse()} or
172\method{ParseFile()} methods are called; calling it after either of
173those have been called causes \exception{ExpatError} to be raised with
174the \member{code} attribute set to
175\constant{errors.XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING}.
176
177\versionadded{2.3}
178\end{methoddesc}
179
Fred Drakeefffe8e2000-10-29 05:10:30 +0000180
Fred Draked79c33a2000-09-25 14:14:30 +0000181\class{xmlparser} objects have the following attributes:
Andrew M. Kuchling0690c862000-08-17 23:15:21 +0000182
Fred Drakef0b095d2002-07-17 20:31:52 +0000183\begin{memberdesc}[xmlparser]{buffer_size}
184The size of the buffer used when \member{buffer_text} is true. This
185value cannot be changed at this time.
186\versionadded{2.3}
187\end{memberdesc}
188
189\begin{memberdesc}[xmlparser]{buffer_text}
190Setting this to true causes the \class{xmlparser} object to buffer
191textual content returned by Expat to avoid multiple calls to the
192\method{CharacterDataHandler()} callback whenever possible. This can
193improve performance substantially since Expat normally breaks
194character data into chunks at every line ending. This attribute is
195false by default, and may be changed at any time.
196\versionadded{2.3}
197\end{memberdesc}
198
199\begin{memberdesc}[xmlparser]{buffer_used}
200If \member{buffer_text} is enabled, the number of bytes stored in the
201buffer. These bytes represent UTF-8 encoded text. This attribute has
202no meaningful interpretation when \member{buffer_text} is false.
203\versionadded{2.3}
204\end{memberdesc}
205
Fred Drake5ed1dac2001-02-08 15:40:33 +0000206\begin{memberdesc}[xmlparser]{ordered_attributes}
207Setting this attribute to a non-zero integer causes the attributes to
208be reported as a list rather than a dictionary. The attributes are
209presented in the order found in the document text. For each
210attribute, two list entries are presented: the attribute name and the
211attribute value. (Older versions of this module also used this
212format.) By default, this attribute is false; it may be changed at
213any time.
214\versionadded{2.1}
215\end{memberdesc}
216
Fred Drakeefffe8e2000-10-29 05:10:30 +0000217\begin{memberdesc}[xmlparser]{returns_unicode}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000218If this attribute is set to a non-zero integer, the handler functions
Thomas Wouters89f507f2006-12-13 04:49:30 +0000219will be passed Unicode strings. If \member{returns_unicode} is
220\constant{False}, 8-bit strings containing UTF-8 encoded data will be
221passed to the handlers. This is \constant{True} by default when
222Python is built with Unicode support.
Fred Drakeb62966c2000-12-07 00:00:21 +0000223\versionchanged[Can be changed at any time to affect the result
Fred Drakee0af35e2001-09-20 20:43:28 +0000224 type]{1.6}
Fred Drakeefffe8e2000-10-29 05:10:30 +0000225\end{memberdesc}
Andrew M. Kuchling0690c862000-08-17 23:15:21 +0000226
Fred Drake5ed1dac2001-02-08 15:40:33 +0000227\begin{memberdesc}[xmlparser]{specified_attributes}
228If set to a non-zero integer, the parser will report only those
229attributes which were specified in the document instance and not those
230which were derived from attribute declarations. Applications which
231set this need to be especially careful to use what additional
232information is available from the declarations as needed to comply
233with the standards for the behavior of XML processors. By default,
234this attribute is false; it may be changed at any time.
235\versionadded{2.1}
236\end{memberdesc}
237
Andrew M. Kuchling0690c862000-08-17 23:15:21 +0000238The following attributes contain values relating to the most recent
239error encountered by an \class{xmlparser} object, and will only have
240correct values once a call to \method{Parse()} or \method{ParseFile()}
Fred Drake523ec572001-02-15 05:37:51 +0000241has raised a \exception{xml.parsers.expat.ExpatError} exception.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000242
Fred Drakeefffe8e2000-10-29 05:10:30 +0000243\begin{memberdesc}[xmlparser]{ErrorByteIndex}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000244Byte index at which an error occurred.
Fred Drakeefffe8e2000-10-29 05:10:30 +0000245\end{memberdesc}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000246
Fred Drakeefffe8e2000-10-29 05:10:30 +0000247\begin{memberdesc}[xmlparser]{ErrorCode}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000248Numeric code specifying the problem. This value can be passed to the
249\function{ErrorString()} function, or compared to one of the constants
Fred Drake523ec572001-02-15 05:37:51 +0000250defined in the \code{errors} object.
Fred Drakeefffe8e2000-10-29 05:10:30 +0000251\end{memberdesc}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000252
Fred Drakeefffe8e2000-10-29 05:10:30 +0000253\begin{memberdesc}[xmlparser]{ErrorColumnNumber}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000254Column number at which an error occurred.
Fred Drakeefffe8e2000-10-29 05:10:30 +0000255\end{memberdesc}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000256
Fred Drakeefffe8e2000-10-29 05:10:30 +0000257\begin{memberdesc}[xmlparser]{ErrorLineNumber}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000258Line number at which an error occurred.
Fred Drakeefffe8e2000-10-29 05:10:30 +0000259\end{memberdesc}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000260
Dave Cole3203efb2004-08-26 00:37:31 +0000261The following attributes contain values relating to the current parse
262location in an \class{xmlparser} object. During a callback reporting
263a parse event they indicate the location of the first of the sequence
264of characters that generated the event. When called outside of a
265callback, the position indicated will be just past the last parse
266event (regardless of whether there was an associated callback).
267\versionadded{2.4}
268
269\begin{memberdesc}[xmlparser]{CurrentByteIndex}
270Current byte index in the parser input.
271\end{memberdesc}
272
273\begin{memberdesc}[xmlparser]{CurrentColumnNumber}
274Current column number in the parser input.
275\end{memberdesc}
276
277\begin{memberdesc}[xmlparser]{CurrentLineNumber}
278Current line number in the parser input.
279\end{memberdesc}
280
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000281Here is the list of handlers that can be set. To set a handler on an
Fred Drakec05cbb02000-07-05 02:03:34 +0000282\class{xmlparser} object \var{o}, use
283\code{\var{o}.\var{handlername} = \var{func}}. \var{handlername} must
284be taken from the following list, and \var{func} must be a callable
285object accepting the correct number of arguments. The arguments are
286all strings, unless otherwise stated.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000287
Fred Drake5ed1dac2001-02-08 15:40:33 +0000288\begin{methoddesc}[xmlparser]{XmlDeclHandler}{version, encoding, standalone}
289Called when the XML declaration is parsed. The XML declaration is the
290(optional) declaration of the applicable version of the XML
291recommendation, the encoding of the document text, and an optional
292``standalone'' declaration. \var{version} and \var{encoding} will be
293strings of the type dictated by the \member{returns_unicode}
294attribute, and \var{standalone} will be \code{1} if the document is
295declared standalone, \code{0} if it is declared not to be standalone,
296or \code{-1} if the standalone clause was omitted.
297This is only available with Expat version 1.95.0 or newer.
298\versionadded{2.1}
299\end{methoddesc}
300
301\begin{methoddesc}[xmlparser]{StartDoctypeDeclHandler}{doctypeName,
302 systemId, publicId,
303 has_internal_subset}
304Called when Expat begins parsing the document type declaration
305(\code{<!DOCTYPE \ldots}). The \var{doctypeName} is provided exactly
306as presented. The \var{systemId} and \var{publicId} parameters give
307the system and public identifiers if specified, or \code{None} if
308omitted. \var{has_internal_subset} will be true if the document
309contains and internal document declaration subset.
310This requires Expat version 1.2 or newer.
311\end{methoddesc}
312
313\begin{methoddesc}[xmlparser]{EndDoctypeDeclHandler}{}
Raymond Hettinger68804312005-01-01 00:28:46 +0000314Called when Expat is done parsing the document type declaration.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000315This requires Expat version 1.2 or newer.
316\end{methoddesc}
317
318\begin{methoddesc}[xmlparser]{ElementDeclHandler}{name, model}
319Called once for each element type declaration. \var{name} is the name
320of the element type, and \var{model} is a representation of the
321content model.
322\end{methoddesc}
323
324\begin{methoddesc}[xmlparser]{AttlistDeclHandler}{elname, attname,
325 type, default, required}
326Called for each declared attribute for an element type. If an
327attribute list declaration declares three attributes, this handler is
328called three times, once for each attribute. \var{elname} is the name
329of the element to which the declaration applies and \var{attname} is
330the name of the attribute declared. The attribute type is a string
331passed as \var{type}; the possible values are \code{'CDATA'},
332\code{'ID'}, \code{'IDREF'}, ...
333\var{default} gives the default value for the attribute used when the
334attribute is not specified by the document instance, or \code{None} if
335there is no default value (\code{\#IMPLIED} values). If the attribute
336is required to be given in the document instance, \var{required} will
337be true.
338This requires Expat version 1.95.0 or newer.
339\end{methoddesc}
340
Fred Drakeefffe8e2000-10-29 05:10:30 +0000341\begin{methoddesc}[xmlparser]{StartElementHandler}{name, attributes}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000342Called for the start of every element. \var{name} is a string
343containing the element name, and \var{attributes} is a dictionary
344mapping attribute names to their values.
345\end{methoddesc}
346
Fred Drakeefffe8e2000-10-29 05:10:30 +0000347\begin{methoddesc}[xmlparser]{EndElementHandler}{name}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000348Called for the end of every element.
349\end{methoddesc}
350
Fred Drakeefffe8e2000-10-29 05:10:30 +0000351\begin{methoddesc}[xmlparser]{ProcessingInstructionHandler}{target, data}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000352Called for every processing instruction.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000353\end{methoddesc}
354
Fred Drakeefffe8e2000-10-29 05:10:30 +0000355\begin{methoddesc}[xmlparser]{CharacterDataHandler}{data}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000356Called for character data. This will be called for normal character
357data, CDATA marked content, and ignorable whitespace. Applications
358which must distinguish these cases can use the
359\member{StartCdataSectionHandler}, \member{EndCdataSectionHandler},
360and \member{ElementDeclHandler} callbacks to collect the required
361information.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000362\end{methoddesc}
363
Fred Drakeefffe8e2000-10-29 05:10:30 +0000364\begin{methoddesc}[xmlparser]{UnparsedEntityDeclHandler}{entityName, base,
365 systemId, publicId,
366 notationName}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000367Called for unparsed (NDATA) entity declarations. This is only present
368for version 1.2 of the Expat library; for more recent versions, use
369\member{EntityDeclHandler} instead. (The underlying function in the
370Expat library has been declared obsolete.)
371\end{methoddesc}
372
373\begin{methoddesc}[xmlparser]{EntityDeclHandler}{entityName,
374 is_parameter_entity, value,
375 base, systemId,
376 publicId,
377 notationName}
378Called for all entity declarations. For parameter and internal
379entities, \var{value} will be a string giving the declared contents
380of the entity; this will be \code{None} for external entities. The
381\var{notationName} parameter will be \code{None} for parsed entities,
382and the name of the notation for unparsed entities.
Raymond Hettinger68804312005-01-01 00:28:46 +0000383\var{is_parameter_entity} will be true if the entity is a parameter
Fred Drake5ed1dac2001-02-08 15:40:33 +0000384entity or false for general entities (most applications only need to
385be concerned with general entities).
386This is only available starting with version 1.95.0 of the Expat
387library.
388\versionadded{2.1}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000389\end{methoddesc}
390
Fred Drakeefffe8e2000-10-29 05:10:30 +0000391\begin{methoddesc}[xmlparser]{NotationDeclHandler}{notationName, base,
392 systemId, publicId}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000393Called for notation declarations. \var{notationName}, \var{base}, and
394\var{systemId}, and \var{publicId} are strings if given. If the
395public identifier is omitted, \var{publicId} will be \code{None}.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000396\end{methoddesc}
397
Fred Drakeefffe8e2000-10-29 05:10:30 +0000398\begin{methoddesc}[xmlparser]{StartNamespaceDeclHandler}{prefix, uri}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000399Called when an element contains a namespace declaration. Namespace
400declarations are processed before the \member{StartElementHandler} is
401called for the element on which declarations are placed.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000402\end{methoddesc}
403
Fred Drakeefffe8e2000-10-29 05:10:30 +0000404\begin{methoddesc}[xmlparser]{EndNamespaceDeclHandler}{prefix}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000405Called when the closing tag is reached for an element
Fred Drake5ed1dac2001-02-08 15:40:33 +0000406that contained a namespace declaration. This is called once for each
407namespace declaration on the element in the reverse of the order for
408which the \member{StartNamespaceDeclHandler} was called to indicate
409the start of each namespace declaration's scope. Calls to this
410handler are made after the corresponding \member{EndElementHandler}
411for the end of the element.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000412\end{methoddesc}
413
Fred Drakeefffe8e2000-10-29 05:10:30 +0000414\begin{methoddesc}[xmlparser]{CommentHandler}{data}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000415Called for comments. \var{data} is the text of the comment, excluding
Fred Drake523ec572001-02-15 05:37:51 +0000416the leading `\code{<!-}\code{-}' and trailing `\code{-}\code{->}'.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000417\end{methoddesc}
418
Fred Drakeefffe8e2000-10-29 05:10:30 +0000419\begin{methoddesc}[xmlparser]{StartCdataSectionHandler}{}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000420Called at the start of a CDATA section. This and
Georg Brandl08caadc2005-12-16 19:23:33 +0000421\member{EndCdataSectionHandler} are needed to be able to identify
Fred Drake5ed1dac2001-02-08 15:40:33 +0000422the syntactical start and end for CDATA sections.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000423\end{methoddesc}
424
Fred Drakeefffe8e2000-10-29 05:10:30 +0000425\begin{methoddesc}[xmlparser]{EndCdataSectionHandler}{}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000426Called at the end of a CDATA section.
427\end{methoddesc}
428
Fred Drakeefffe8e2000-10-29 05:10:30 +0000429\begin{methoddesc}[xmlparser]{DefaultHandler}{data}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000430Called for any characters in the XML document for
431which no applicable handler has been specified. This means
432characters that are part of a construct which could be reported, but
433for which no handler has been supplied.
434\end{methoddesc}
435
Fred Drakeefffe8e2000-10-29 05:10:30 +0000436\begin{methoddesc}[xmlparser]{DefaultHandlerExpand}{data}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000437This is the same as the \function{DefaultHandler},
438but doesn't inhibit expansion of internal entities.
439The entity reference will not be passed to the default handler.
440\end{methoddesc}
441
Fred Drake5ed1dac2001-02-08 15:40:33 +0000442\begin{methoddesc}[xmlparser]{NotStandaloneHandler}{} Called if the
443XML document hasn't been declared as being a standalone document.
444This happens when there is an external subset or a reference to a
445parameter entity, but the XML declaration does not set standalone to
446\code{yes} in an XML declaration. If this handler returns \code{0},
447then the parser will throw an \constant{XML_ERROR_NOT_STANDALONE}
448error. If this handler is not set, no exception is raised by the
449parser for this condition.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000450\end{methoddesc}
451
Fred Drakeefffe8e2000-10-29 05:10:30 +0000452\begin{methoddesc}[xmlparser]{ExternalEntityRefHandler}{context, base,
453 systemId, publicId}
Fred Drake5ed1dac2001-02-08 15:40:33 +0000454Called for references to external entities. \var{base} is the current
455base, as set by a previous call to \method{SetBase()}. The public and
456system identifiers, \var{systemId} and \var{publicId}, are strings if
457given; if the public identifier is not given, \var{publicId} will be
Fred Drake523ec572001-02-15 05:37:51 +0000458\code{None}. The \var{context} value is opaque and should only be
459used as described below.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000460
461For external entities to be parsed, this handler must be implemented.
462It is responsible for creating the sub-parser using
Fred Drake523ec572001-02-15 05:37:51 +0000463\code{ExternalEntityParserCreate(\var{context})}, initializing it with
464the appropriate callbacks, and parsing the entity. This handler
465should return an integer; if it returns \code{0}, the parser will
466throw an \constant{XML_ERROR_EXTERNAL_ENTITY_HANDLING} error,
467otherwise parsing will continue.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000468
469If this handler is not provided, external entities are reported by the
470\member{DefaultHandler} callback, if provided.
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000471\end{methoddesc}
472
473
Fred Drake1d8ad2b2001-02-14 18:54:32 +0000474\subsection{ExpatError Exceptions \label{expaterror-objects}}
475\sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
476
477\exception{ExpatError} exceptions have a number of interesting
478attributes:
479
480\begin{memberdesc}[ExpatError]{code}
481 Expat's internal error number for the specific error. This will
482 match one of the constants defined in the \code{errors} object from
483 this module.
484 \versionadded{2.1}
485\end{memberdesc}
486
487\begin{memberdesc}[ExpatError]{lineno}
488 Line number on which the error was detected. The first line is
489 numbered \code{1}.
490 \versionadded{2.1}
491\end{memberdesc}
492
493\begin{memberdesc}[ExpatError]{offset}
494 Character offset into the line where the error occurred. The first
495 column is numbered \code{0}.
496 \versionadded{2.1}
497\end{memberdesc}
498
499
Fred Drake7fbc85c2000-09-23 04:47:56 +0000500\subsection{Example \label{expat-example}}
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000501
Fred Drakec05cbb02000-07-05 02:03:34 +0000502The following program defines three handlers that just print out their
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000503arguments.
504
505\begin{verbatim}
Fred Drake7fbc85c2000-09-23 04:47:56 +0000506import xml.parsers.expat
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000507
508# 3 handler functions
509def start_element(name, attrs):
510 print 'Start element:', name, attrs
511def end_element(name):
512 print 'End element:', name
513def char_data(data):
514 print 'Character data:', repr(data)
515
Fred Drake7fbc85c2000-09-23 04:47:56 +0000516p = xml.parsers.expat.ParserCreate()
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000517
518p.StartElementHandler = start_element
Fred Drake7fbc85c2000-09-23 04:47:56 +0000519p.EndElementHandler = end_element
520p.CharacterDataHandler = char_data
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000521
522p.Parse("""<?xml version="1.0"?>
523<parent id="top"><child1 name="paul">Text goes here</child1>
524<child2 name="fred">More text</child2>
Fred Drakea41b2bb2002-12-03 22:57:37 +0000525</parent>""", 1)
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000526\end{verbatim}
527
528The output from this program is:
529
530\begin{verbatim}
531Start element: parent {'id': 'top'}
532Start element: child1 {'name': 'paul'}
533Character data: 'Text goes here'
534End element: child1
Ka-Ping Yeefa004ad2001-01-24 17:19:08 +0000535Character data: '\n'
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000536Start element: child2 {'name': 'fred'}
537Character data: 'More text'
538End element: child2
Ka-Ping Yeefa004ad2001-01-24 17:19:08 +0000539Character data: '\n'
Andrew M. Kuchling6b14eeb2000-06-11 02:42:07 +0000540End element: parent
541\end{verbatim}
Fred Drakec05cbb02000-07-05 02:03:34 +0000542
543
Fred Drake5ed1dac2001-02-08 15:40:33 +0000544\subsection{Content Model Descriptions \label{expat-content-models}}
545\sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
546
547Content modules are described using nested tuples. Each tuple
548contains four values: the type, the quantifier, the name, and a tuple
549of children. Children are simply additional content module
550descriptions.
551
552The values of the first two fields are constants defined in the
553\code{model} object of the \module{xml.parsers.expat} module. These
554constants can be collected in two groups: the model type group and the
555quantifier group.
556
557The constants in the model type group are:
558
559\begin{datadescni}{XML_CTYPE_ANY}
560The element named by the model name was declared to have a content
561model of \code{ANY}.
562\end{datadescni}
563
564\begin{datadescni}{XML_CTYPE_CHOICE}
565The named element allows a choice from a number of options; this is
566used for content models such as \code{(A | B | C)}.
567\end{datadescni}
568
569\begin{datadescni}{XML_CTYPE_EMPTY}
570Elements which are declared to be \code{EMPTY} have this model type.
571\end{datadescni}
572
573\begin{datadescni}{XML_CTYPE_MIXED}
574\end{datadescni}
575
576\begin{datadescni}{XML_CTYPE_NAME}
577\end{datadescni}
578
579\begin{datadescni}{XML_CTYPE_SEQ}
580Models which represent a series of models which follow one after the
581other are indicated with this model type. This is used for models
582such as \code{(A, B, C)}.
583\end{datadescni}
584
585
586The constants in the quantifier group are:
587
588\begin{datadescni}{XML_CQUANT_NONE}
Fred Drakee0af35e2001-09-20 20:43:28 +0000589No modifier is given, so it can appear exactly once, as for \code{A}.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000590\end{datadescni}
591
592\begin{datadescni}{XML_CQUANT_OPT}
Fred Drakee0af35e2001-09-20 20:43:28 +0000593The model is optional: it can appear once or not at all, as for
Fred Drake5ed1dac2001-02-08 15:40:33 +0000594\code{A?}.
595\end{datadescni}
596
597\begin{datadescni}{XML_CQUANT_PLUS}
Fred Drakee0af35e2001-09-20 20:43:28 +0000598The model must occur one or more times (like \code{A+}).
Fred Drake5ed1dac2001-02-08 15:40:33 +0000599\end{datadescni}
600
601\begin{datadescni}{XML_CQUANT_REP}
602The model must occur zero or more times, as for \code{A*}.
603\end{datadescni}
604
605
Fred Drake7fbc85c2000-09-23 04:47:56 +0000606\subsection{Expat error constants \label{expat-errors}}
Fred Drakec05cbb02000-07-05 02:03:34 +0000607
Fred Drake1d8ad2b2001-02-14 18:54:32 +0000608The following constants are provided in the \code{errors} object of
609the \refmodule{xml.parsers.expat} module. These constants are useful
610in interpreting some of the attributes of the \exception{ExpatError}
611exception objects raised when an error has occurred.
Fred Drakec05cbb02000-07-05 02:03:34 +0000612
Fred Drake7fbc85c2000-09-23 04:47:56 +0000613The \code{errors} object has the following attributes:
Fred Drakec05cbb02000-07-05 02:03:34 +0000614
Fred Drake5ed1dac2001-02-08 15:40:33 +0000615\begin{datadescni}{XML_ERROR_ASYNC_ENTITY}
616\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000617
Fred Drake5ed1dac2001-02-08 15:40:33 +0000618\begin{datadescni}{XML_ERROR_ATTRIBUTE_EXTERNAL_ENTITY_REF}
619An entity reference in an attribute value referred to an external
620entity instead of an internal entity.
621\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000622
Fred Drake5ed1dac2001-02-08 15:40:33 +0000623\begin{datadescni}{XML_ERROR_BAD_CHAR_REF}
Fred Drakee0af35e2001-09-20 20:43:28 +0000624A character reference referred to a character which is illegal in XML
Raymond Hettingerbf3a7522003-05-12 03:23:51 +0000625(for example, character \code{0}, or `\code{\&\#0;}').
Fred Drake5ed1dac2001-02-08 15:40:33 +0000626\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000627
Fred Drake5ed1dac2001-02-08 15:40:33 +0000628\begin{datadescni}{XML_ERROR_BINARY_ENTITY_REF}
Fred Drakee0af35e2001-09-20 20:43:28 +0000629An entity reference referred to an entity which was declared with a
630notation, so cannot be parsed.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000631\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000632
Fred Drake5ed1dac2001-02-08 15:40:33 +0000633\begin{datadescni}{XML_ERROR_DUPLICATE_ATTRIBUTE}
Fred Drakeacab3d62000-07-11 16:30:30 +0000634An attribute was used more than once in a start tag.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000635\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000636
Fred Drake5ed1dac2001-02-08 15:40:33 +0000637\begin{datadescni}{XML_ERROR_INCORRECT_ENCODING}
638\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000639
Fred Drake5ed1dac2001-02-08 15:40:33 +0000640\begin{datadescni}{XML_ERROR_INVALID_TOKEN}
Fred Drakee0af35e2001-09-20 20:43:28 +0000641Raised when an input byte could not properly be assigned to a
642character; for example, a NUL byte (value \code{0}) in a UTF-8 input
643stream.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000644\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000645
Fred Drake5ed1dac2001-02-08 15:40:33 +0000646\begin{datadescni}{XML_ERROR_JUNK_AFTER_DOC_ELEMENT}
Fred Drakeacab3d62000-07-11 16:30:30 +0000647Something other than whitespace occurred after the document element.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000648\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000649
Fred Drake5ed1dac2001-02-08 15:40:33 +0000650\begin{datadescni}{XML_ERROR_MISPLACED_XML_PI}
Fred Drakee0af35e2001-09-20 20:43:28 +0000651An XML declaration was found somewhere other than the start of the
652input data.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000653\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000654
Fred Drake5ed1dac2001-02-08 15:40:33 +0000655\begin{datadescni}{XML_ERROR_NO_ELEMENTS}
Fred Drakee0af35e2001-09-20 20:43:28 +0000656The document contains no elements (XML requires all documents to
657contain exactly one top-level element)..
Fred Drake5ed1dac2001-02-08 15:40:33 +0000658\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000659
Fred Drake5ed1dac2001-02-08 15:40:33 +0000660\begin{datadescni}{XML_ERROR_NO_MEMORY}
Fred Drakeacab3d62000-07-11 16:30:30 +0000661Expat was not able to allocate memory internally.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000662\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000663
Fred Drake5ed1dac2001-02-08 15:40:33 +0000664\begin{datadescni}{XML_ERROR_PARAM_ENTITY_REF}
Fred Drakee0af35e2001-09-20 20:43:28 +0000665A parameter entity reference was found where it was not allowed.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000666\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000667
Fred Drake5ed1dac2001-02-08 15:40:33 +0000668\begin{datadescni}{XML_ERROR_PARTIAL_CHAR}
Fred Drakefb568ca2004-08-10 16:47:18 +0000669An incomplete character was found in the input.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000670\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000671
Fred Drake5ed1dac2001-02-08 15:40:33 +0000672\begin{datadescni}{XML_ERROR_RECURSIVE_ENTITY_REF}
Fred Drakee0af35e2001-09-20 20:43:28 +0000673An entity reference contained another reference to the same entity;
674possibly via a different name, and possibly indirectly.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000675\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000676
Fred Drake5ed1dac2001-02-08 15:40:33 +0000677\begin{datadescni}{XML_ERROR_SYNTAX}
Fred Drakeacab3d62000-07-11 16:30:30 +0000678Some unspecified syntax error was encountered.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000679\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000680
Fred Drake5ed1dac2001-02-08 15:40:33 +0000681\begin{datadescni}{XML_ERROR_TAG_MISMATCH}
Fred Drakeacab3d62000-07-11 16:30:30 +0000682An end tag did not match the innermost open start tag.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000683\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000684
Fred Drake5ed1dac2001-02-08 15:40:33 +0000685\begin{datadescni}{XML_ERROR_UNCLOSED_TOKEN}
Fred Drakee0af35e2001-09-20 20:43:28 +0000686Some token (such as a start tag) was not closed before the end of the
687stream or the next token was encountered.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000688\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000689
Fred Drake5ed1dac2001-02-08 15:40:33 +0000690\begin{datadescni}{XML_ERROR_UNDEFINED_ENTITY}
Fred Drakeacab3d62000-07-11 16:30:30 +0000691A reference was made to a entity which was not defined.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000692\end{datadescni}
Fred Drakeacab3d62000-07-11 16:30:30 +0000693
Fred Drake5ed1dac2001-02-08 15:40:33 +0000694\begin{datadescni}{XML_ERROR_UNKNOWN_ENCODING}
Fred Drakeacab3d62000-07-11 16:30:30 +0000695The document encoding is not supported by Expat.
Fred Drake5ed1dac2001-02-08 15:40:33 +0000696\end{datadescni}
Fred Drakefb568ca2004-08-10 16:47:18 +0000697
698\begin{datadescni}{XML_ERROR_UNCLOSED_CDATA_SECTION}
699A CDATA marked section was not closed.
700\end{datadescni}
701
702\begin{datadescni}{XML_ERROR_EXTERNAL_ENTITY_HANDLING}
703\end{datadescni}
704
705\begin{datadescni}{XML_ERROR_NOT_STANDALONE}
706The parser determined that the document was not ``standalone'' though
707it declared itself to be in the XML declaration, and the
708\member{NotStandaloneHandler} was set and returned \code{0}.
709\end{datadescni}
710
711\begin{datadescni}{XML_ERROR_UNEXPECTED_STATE}
712\end{datadescni}
713
714\begin{datadescni}{XML_ERROR_ENTITY_DECLARED_IN_PE}
715\end{datadescni}
716
717\begin{datadescni}{XML_ERROR_FEATURE_REQUIRES_XML_DTD}
718An operation was requested that requires DTD support to be compiled
719in, but Expat was configured without DTD support. This should never
720be reported by a standard build of the \module{xml.parsers.expat}
721module.
722\end{datadescni}
723
724\begin{datadescni}{XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING}
725A behavioral change was requested after parsing started that can only
726be changed before parsing has started. This is (currently) only
727raised by \method{UseForeignDTD()}.
728\end{datadescni}
729
730\begin{datadescni}{XML_ERROR_UNBOUND_PREFIX}
731An undeclared prefix was found when namespace processing was enabled.
732\end{datadescni}
733
734\begin{datadescni}{XML_ERROR_UNDECLARING_PREFIX}
735The document attempted to remove the namespace declaration associated
736with a prefix.
737\end{datadescni}
738
739\begin{datadescni}{XML_ERROR_INCOMPLETE_PE}
740A parameter entity contained incomplete markup.
741\end{datadescni}
742
743\begin{datadescni}{XML_ERROR_XML_DECL}
744The document contained no document element at all.
745\end{datadescni}
746
747\begin{datadescni}{XML_ERROR_TEXT_DECL}
748There was an error parsing a text declaration in an external entity.
749\end{datadescni}
750
751\begin{datadescni}{XML_ERROR_PUBLICID}
752Characters were found in the public id that are not allowed.
753\end{datadescni}
754
755\begin{datadescni}{XML_ERROR_SUSPENDED}
756The requested operation was made on a suspended parser, but isn't
757allowed. This includes attempts to provide additional input or to
758stop the parser.
759\end{datadescni}
760
761\begin{datadescni}{XML_ERROR_NOT_SUSPENDED}
762An attempt to resume the parser was made when the parser had not been
763suspended.
764\end{datadescni}
765
766\begin{datadescni}{XML_ERROR_ABORTED}
767This should not be reported to Python applications.
768\end{datadescni}
769
770\begin{datadescni}{XML_ERROR_FINISHED}
771The requested operation was made on a parser which was finished
772parsing input, but isn't allowed. This includes attempts to provide
773additional input or to stop the parser.
774\end{datadescni}
775
776\begin{datadescni}{XML_ERROR_SUSPEND_PE}
777\end{datadescni}