expatreader.py 15 KB

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  1. """
  2. SAX driver for the pyexpat C module. This driver works with
  3. pyexpat.__version__ == '2.22'.
  4. """
  5. version = "0.20"
  6. from xml.sax._exceptions import *
  7. from xml.sax.handler import feature_validation, feature_namespaces
  8. from xml.sax.handler import feature_namespace_prefixes
  9. from xml.sax.handler import feature_external_ges, feature_external_pes
  10. from xml.sax.handler import feature_string_interning
  11. from xml.sax.handler import property_xml_string, property_interning_dict
  12. # xml.parsers.expat does not raise ImportError in Jython
  13. import sys
  14. if sys.platform[:4] == "java":
  15. raise SAXReaderNotAvailable("expat not available in Java", None)
  16. del sys
  17. try:
  18. from xml.parsers import expat
  19. except ImportError:
  20. raise SAXReaderNotAvailable("expat not supported", None)
  21. else:
  22. if not hasattr(expat, "ParserCreate"):
  23. raise SAXReaderNotAvailable("expat not supported", None)
  24. from xml.sax import xmlreader, saxutils, handler
  25. AttributesImpl = xmlreader.AttributesImpl
  26. AttributesNSImpl = xmlreader.AttributesNSImpl
  27. # If we're using a sufficiently recent version of Python, we can use
  28. # weak references to avoid cycles between the parser and content
  29. # handler, otherwise we'll just have to pretend.
  30. try:
  31. import _weakref
  32. except ImportError:
  33. def _mkproxy(o):
  34. return o
  35. else:
  36. import weakref
  37. _mkproxy = weakref.proxy
  38. del weakref, _weakref
  39. class _ClosedParser:
  40. pass
  41. # --- ExpatLocator
  42. class ExpatLocator(xmlreader.Locator):
  43. """Locator for use with the ExpatParser class.
  44. This uses a weak reference to the parser object to avoid creating
  45. a circular reference between the parser and the content handler.
  46. """
  47. def __init__(self, parser):
  48. self._ref = _mkproxy(parser)
  49. def getColumnNumber(self):
  50. parser = self._ref
  51. if parser._parser is None:
  52. return None
  53. return parser._parser.ErrorColumnNumber
  54. def getLineNumber(self):
  55. parser = self._ref
  56. if parser._parser is None:
  57. return 1
  58. return parser._parser.ErrorLineNumber
  59. def getPublicId(self):
  60. parser = self._ref
  61. if parser is None:
  62. return None
  63. return parser._source.getPublicId()
  64. def getSystemId(self):
  65. parser = self._ref
  66. if parser is None:
  67. return None
  68. return parser._source.getSystemId()
  69. # --- ExpatParser
  70. class ExpatParser(xmlreader.IncrementalParser, xmlreader.Locator):
  71. """SAX driver for the pyexpat C module."""
  72. def __init__(self, namespaceHandling=0, bufsize=2**16-20):
  73. xmlreader.IncrementalParser.__init__(self, bufsize)
  74. self._source = xmlreader.InputSource()
  75. self._parser = None
  76. self._namespaces = namespaceHandling
  77. self._lex_handler_prop = None
  78. self._parsing = 0
  79. self._entity_stack = []
  80. self._external_ges = 1
  81. self._interning = None
  82. # XMLReader methods
  83. def parse(self, source):
  84. "Parse an XML document from a URL or an InputSource."
  85. source = saxutils.prepare_input_source(source)
  86. self._source = source
  87. self.reset()
  88. self._cont_handler.setDocumentLocator(ExpatLocator(self))
  89. xmlreader.IncrementalParser.parse(self, source)
  90. def prepareParser(self, source):
  91. if source.getSystemId() is not None:
  92. self._parser.SetBase(source.getSystemId())
  93. # Redefined setContentHandler to allow changing handlers during parsing
  94. def setContentHandler(self, handler):
  95. xmlreader.IncrementalParser.setContentHandler(self, handler)
  96. if self._parsing:
  97. self._reset_cont_handler()
  98. def getFeature(self, name):
  99. if name == feature_namespaces:
  100. return self._namespaces
  101. elif name == feature_string_interning:
  102. return self._interning is not None
  103. elif name in (feature_validation, feature_external_pes,
  104. feature_namespace_prefixes):
  105. return 0
  106. elif name == feature_external_ges:
  107. return self._external_ges
  108. raise SAXNotRecognizedException("Feature '%s' not recognized" % name)
  109. def setFeature(self, name, state):
  110. if self._parsing:
  111. raise SAXNotSupportedException("Cannot set features while parsing")
  112. if name == feature_namespaces:
  113. self._namespaces = state
  114. elif name == feature_external_ges:
  115. self._external_ges = state
  116. elif name == feature_string_interning:
  117. if state:
  118. if self._interning is None:
  119. self._interning = {}
  120. else:
  121. self._interning = None
  122. elif name == feature_validation:
  123. if state:
  124. raise SAXNotSupportedException(
  125. "expat does not support validation")
  126. elif name == feature_external_pes:
  127. if state:
  128. raise SAXNotSupportedException(
  129. "expat does not read external parameter entities")
  130. elif name == feature_namespace_prefixes:
  131. if state:
  132. raise SAXNotSupportedException(
  133. "expat does not report namespace prefixes")
  134. else:
  135. raise SAXNotRecognizedException(
  136. "Feature '%s' not recognized" % name)
  137. def getProperty(self, name):
  138. if name == handler.property_lexical_handler:
  139. return self._lex_handler_prop
  140. elif name == property_interning_dict:
  141. return self._interning
  142. elif name == property_xml_string:
  143. if self._parser:
  144. if hasattr(self._parser, "GetInputContext"):
  145. return self._parser.GetInputContext()
  146. else:
  147. raise SAXNotRecognizedException(
  148. "This version of expat does not support getting"
  149. " the XML string")
  150. else:
  151. raise SAXNotSupportedException(
  152. "XML string cannot be returned when not parsing")
  153. raise SAXNotRecognizedException("Property '%s' not recognized" % name)
  154. def setProperty(self, name, value):
  155. if name == handler.property_lexical_handler:
  156. self._lex_handler_prop = value
  157. if self._parsing:
  158. self._reset_lex_handler_prop()
  159. elif name == property_interning_dict:
  160. self._interning = value
  161. elif name == property_xml_string:
  162. raise SAXNotSupportedException("Property '%s' cannot be set" %
  163. name)
  164. else:
  165. raise SAXNotRecognizedException("Property '%s' not recognized" %
  166. name)
  167. # IncrementalParser methods
  168. def feed(self, data, isFinal = 0):
  169. if not self._parsing:
  170. self.reset()
  171. self._parsing = 1
  172. self._cont_handler.startDocument()
  173. try:
  174. # The isFinal parameter is internal to the expat reader.
  175. # If it is set to true, expat will check validity of the entire
  176. # document. When feeding chunks, they are not normally final -
  177. # except when invoked from close.
  178. self._parser.Parse(data, isFinal)
  179. except expat.error as e:
  180. exc = SAXParseException(expat.ErrorString(e.code), e, self)
  181. # FIXME: when to invoke error()?
  182. self._err_handler.fatalError(exc)
  183. def close(self):
  184. if (self._entity_stack or self._parser is None or
  185. isinstance(self._parser, _ClosedParser)):
  186. # If we are completing an external entity, do nothing here
  187. return
  188. try:
  189. self.feed("", isFinal = 1)
  190. self._cont_handler.endDocument()
  191. self._parsing = 0
  192. # break cycle created by expat handlers pointing to our methods
  193. self._parser = None
  194. finally:
  195. self._parsing = 0
  196. if self._parser is not None:
  197. # Keep ErrorColumnNumber and ErrorLineNumber after closing.
  198. parser = _ClosedParser()
  199. parser.ErrorColumnNumber = self._parser.ErrorColumnNumber
  200. parser.ErrorLineNumber = self._parser.ErrorLineNumber
  201. self._parser = parser
  202. try:
  203. file = self._source.getCharacterStream()
  204. if file is not None:
  205. file.close()
  206. finally:
  207. file = self._source.getByteStream()
  208. if file is not None:
  209. file.close()
  210. def _reset_cont_handler(self):
  211. self._parser.ProcessingInstructionHandler = \
  212. self._cont_handler.processingInstruction
  213. self._parser.CharacterDataHandler = self._cont_handler.characters
  214. def _reset_lex_handler_prop(self):
  215. lex = self._lex_handler_prop
  216. parser = self._parser
  217. if lex is None:
  218. parser.CommentHandler = None
  219. parser.StartCdataSectionHandler = None
  220. parser.EndCdataSectionHandler = None
  221. parser.StartDoctypeDeclHandler = None
  222. parser.EndDoctypeDeclHandler = None
  223. else:
  224. parser.CommentHandler = lex.comment
  225. parser.StartCdataSectionHandler = lex.startCDATA
  226. parser.EndCdataSectionHandler = lex.endCDATA
  227. parser.StartDoctypeDeclHandler = self.start_doctype_decl
  228. parser.EndDoctypeDeclHandler = lex.endDTD
  229. def reset(self):
  230. if self._namespaces:
  231. self._parser = expat.ParserCreate(self._source.getEncoding(), " ",
  232. intern=self._interning)
  233. self._parser.namespace_prefixes = 1
  234. self._parser.StartElementHandler = self.start_element_ns
  235. self._parser.EndElementHandler = self.end_element_ns
  236. else:
  237. self._parser = expat.ParserCreate(self._source.getEncoding(),
  238. intern = self._interning)
  239. self._parser.StartElementHandler = self.start_element
  240. self._parser.EndElementHandler = self.end_element
  241. self._reset_cont_handler()
  242. self._parser.UnparsedEntityDeclHandler = self.unparsed_entity_decl
  243. self._parser.NotationDeclHandler = self.notation_decl
  244. self._parser.StartNamespaceDeclHandler = self.start_namespace_decl
  245. self._parser.EndNamespaceDeclHandler = self.end_namespace_decl
  246. self._decl_handler_prop = None
  247. if self._lex_handler_prop:
  248. self._reset_lex_handler_prop()
  249. # self._parser.DefaultHandler =
  250. # self._parser.DefaultHandlerExpand =
  251. # self._parser.NotStandaloneHandler =
  252. self._parser.ExternalEntityRefHandler = self.external_entity_ref
  253. try:
  254. self._parser.SkippedEntityHandler = self.skipped_entity_handler
  255. except AttributeError:
  256. # This pyexpat does not support SkippedEntity
  257. pass
  258. self._parser.SetParamEntityParsing(
  259. expat.XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE)
  260. self._parsing = 0
  261. self._entity_stack = []
  262. # Locator methods
  263. def getColumnNumber(self):
  264. if self._parser is None:
  265. return None
  266. return self._parser.ErrorColumnNumber
  267. def getLineNumber(self):
  268. if self._parser is None:
  269. return 1
  270. return self._parser.ErrorLineNumber
  271. def getPublicId(self):
  272. return self._source.getPublicId()
  273. def getSystemId(self):
  274. return self._source.getSystemId()
  275. # event handlers
  276. def start_element(self, name, attrs):
  277. self._cont_handler.startElement(name, AttributesImpl(attrs))
  278. def end_element(self, name):
  279. self._cont_handler.endElement(name)
  280. def start_element_ns(self, name, attrs):
  281. pair = name.split()
  282. if len(pair) == 1:
  283. # no namespace
  284. pair = (None, name)
  285. elif len(pair) == 3:
  286. pair = pair[0], pair[1]
  287. else:
  288. # default namespace
  289. pair = tuple(pair)
  290. newattrs = {}
  291. qnames = {}
  292. for (aname, value) in attrs.items():
  293. parts = aname.split()
  294. length = len(parts)
  295. if length == 1:
  296. # no namespace
  297. qname = aname
  298. apair = (None, aname)
  299. elif length == 3:
  300. qname = "%s:%s" % (parts[2], parts[1])
  301. apair = parts[0], parts[1]
  302. else:
  303. # default namespace
  304. qname = parts[1]
  305. apair = tuple(parts)
  306. newattrs[apair] = value
  307. qnames[apair] = qname
  308. self._cont_handler.startElementNS(pair, None,
  309. AttributesNSImpl(newattrs, qnames))
  310. def end_element_ns(self, name):
  311. pair = name.split()
  312. if len(pair) == 1:
  313. pair = (None, name)
  314. elif len(pair) == 3:
  315. pair = pair[0], pair[1]
  316. else:
  317. pair = tuple(pair)
  318. self._cont_handler.endElementNS(pair, None)
  319. # this is not used (call directly to ContentHandler)
  320. def processing_instruction(self, target, data):
  321. self._cont_handler.processingInstruction(target, data)
  322. # this is not used (call directly to ContentHandler)
  323. def character_data(self, data):
  324. self._cont_handler.characters(data)
  325. def start_namespace_decl(self, prefix, uri):
  326. self._cont_handler.startPrefixMapping(prefix, uri)
  327. def end_namespace_decl(self, prefix):
  328. self._cont_handler.endPrefixMapping(prefix)
  329. def start_doctype_decl(self, name, sysid, pubid, has_internal_subset):
  330. self._lex_handler_prop.startDTD(name, pubid, sysid)
  331. def unparsed_entity_decl(self, name, base, sysid, pubid, notation_name):
  332. self._dtd_handler.unparsedEntityDecl(name, pubid, sysid, notation_name)
  333. def notation_decl(self, name, base, sysid, pubid):
  334. self._dtd_handler.notationDecl(name, pubid, sysid)
  335. def external_entity_ref(self, context, base, sysid, pubid):
  336. if not self._external_ges:
  337. return 1
  338. source = self._ent_handler.resolveEntity(pubid, sysid)
  339. source = saxutils.prepare_input_source(source,
  340. self._source.getSystemId() or
  341. "")
  342. self._entity_stack.append((self._parser, self._source))
  343. self._parser = self._parser.ExternalEntityParserCreate(context)
  344. self._source = source
  345. try:
  346. xmlreader.IncrementalParser.parse(self, source)
  347. except:
  348. return 0 # FIXME: save error info here?
  349. (self._parser, self._source) = self._entity_stack[-1]
  350. del self._entity_stack[-1]
  351. return 1
  352. def skipped_entity_handler(self, name, is_pe):
  353. if is_pe:
  354. # The SAX spec requires to report skipped PEs with a '%'
  355. name = '%'+name
  356. self._cont_handler.skippedEntity(name)
  357. # ---
  358. def create_parser(*args, **kwargs):
  359. return ExpatParser(*args, **kwargs)
  360. # ---
  361. if __name__ == "__main__":
  362. import xml.sax.saxutils
  363. p = create_parser()
  364. p.setContentHandler(xml.sax.saxutils.XMLGenerator())
  365. p.setErrorHandler(xml.sax.ErrorHandler())
  366. p.parse("http://www.ibiblio.org/xml/examples/shakespeare/hamlet.xml")