Lib/xmlcore/dom/pulldom.py

   1 import xmlcore.sax
   2 import xmlcore.sax.handler
   3 import types
   4
   5 try:
   6     _StringTypes = [types.StringType, types.UnicodeType]
   7 except AttributeError:
   8     _StringTypes = [types.StringType]
   9
  10 START_ELEMENT = "START_ELEMENT"
  11 END_ELEMENT = "END_ELEMENT"
  12 COMMENT = "COMMENT"
  13 START_DOCUMENT = "START_DOCUMENT"
  14 END_DOCUMENT = "END_DOCUMENT"
  15 PROCESSING_INSTRUCTION = "PROCESSING_INSTRUCTION"
  16 IGNORABLE_WHITESPACE = "IGNORABLE_WHITESPACE"
  17 CHARACTERS = "CHARACTERS"
  18
  19 class PullDOM(xmlcore.sax.ContentHandler):
  20     _locator = None
  21     document = None
  22
  23     def __init__(self, documentFactory=None):
  24         from xmlcore.dom import XML_NAMESPACE
  25         self.documentFactory = documentFactory
  26         self.firstEvent = [None, None]
  27         self.lastEvent = self.firstEvent
  28         self.elementStack = []
  29         self.push = self.elementStack.append
  30         try:
  31             self.pop = self.elementStack.pop
  32         except AttributeError:
  33             # use class' pop instead
  34             pass
  35         self._ns_contexts = [{XML_NAMESPACE:'xml'}] # contains uri -> prefix dicts
  36         self._current_context = self._ns_contexts[-1]
  37         self.pending_events = []
  38
  39     def pop(self):
  40         result = self.elementStack[-1]
  41         del self.elementStack[-1]
  42         return result
  43
  44     def setDocumentLocator(self, locator):
  45         self._locator = locator
  46
  47     def startPrefixMapping(self, prefix, uri):
  48         if not hasattr(self, '_xmlns_attrs'):
  49             self._xmlns_attrs = []
  50         self._xmlns_attrs.append((prefix or 'xmlns', uri))
  51         self._ns_contexts.append(self._current_context.copy())
  52         self._current_context[uri] = prefix or None
  53
  54     def endPrefixMapping(self, prefix):
  55         self._current_context = self._ns_contexts.pop()
  56
  57     def startElementNS(self, name, tagName , attrs):
  58         # Retrieve xml namespace declaration attributes.
  59         xmlns_uri = 'http://www.w3.org/2000/xmlns/'
  60         xmlns_attrs = getattr(self, '_xmlns_attrs', None)
  61         if xmlns_attrs is not None:
  62             for aname, value in xmlns_attrs:
  63                 attrs._attrs[(xmlns_uri, aname)] = value
  64             self._xmlns_attrs = []
  65         uri, localname = name
  66         if uri:
  67             # When using namespaces, the reader may or may not
  68             # provide us with the original name. If not, create
  69             # *a* valid tagName from the current context.
  70             if tagName is None:
  71                 prefix = self._current_context[uri]
  72                 if prefix:
  73                     tagName = prefix + ":" + localname
  74                 else:
  75                     tagName = localname
  76             if self.document:
  77                 node = self.document.createElementNS(uri, tagName)
  78             else:
  79                 node = self.buildDocument(uri, tagName)
  80         else:
  81             # When the tagname is not prefixed, it just appears as
  82             # localname
  83             if self.document:
  84                 node = self.document.createElement(localname)
  85             else:
  86                 node = self.buildDocument(None, localname)
  87
  88         for aname,value in attrs.items():
  89             a_uri, a_localname = aname
  90             if a_uri == xmlns_uri:
  91                 if a_localname == 'xmlns':
  92                     qname = a_localname
  93                 else:
  94                     qname = 'xmlns:' + a_localname
  95                 attr = self.document.createAttributeNS(a_uri, qname)
  96                 node.setAttributeNodeNS(attr)
  97             elif a_uri:
  98                 prefix = self._current_context[a_uri]
  99                 if prefix:
 100                     qname = prefix + ":" + a_localname
 101                 else:
 102                     qname = a_localname
 103                 attr = self.document.createAttributeNS(a_uri, qname)
 104                 node.setAttributeNodeNS(attr)
 105             else:
 106                 attr = self.document.createAttribute(a_localname)
 107                 node.setAttributeNode(attr)
 108             attr.value = value
 109
 110         self.lastEvent[1] = [(START_ELEMENT, node), None]
 111         self.lastEvent = self.lastEvent[1]
 112         self.push(node)
 113
 114     def endElementNS(self, name, tagName):
 115         self.lastEvent[1] = [(END_ELEMENT, self.pop()), None]
 116         self.lastEvent = self.lastEvent[1]
 117
 118     def startElement(self, name, attrs):
 119         if self.document:
 120             node = self.document.createElement(name)
 121         else:
 122             node = self.buildDocument(None, name)
 123
 124         for aname,value in attrs.items():
 125             attr = self.document.createAttribute(aname)
 126             attr.value = value
 127             node.setAttributeNode(attr)
 128
 129         self.lastEvent[1] = [(START_ELEMENT, node), None]
 130         self.lastEvent = self.lastEvent[1]
 131         self.push(node)
 132
 133     def endElement(self, name):
 134         self.lastEvent[1] = [(END_ELEMENT, self.pop()), None]
 135         self.lastEvent = self.lastEvent[1]
 136
 137     def comment(self, s):
 138         if self.document:
 139             node = self.document.createComment(s)
 140             self.lastEvent[1] = [(COMMENT, node), None]
 141             self.lastEvent = self.lastEvent[1]
 142         else:
 143             event = [(COMMENT, s), None]
 144             self.pending_events.append(event)
 145
 146     def processingInstruction(self, target, data):
 147         if self.document:
 148             node = self.document.createProcessingInstruction(target, data)
 149             self.lastEvent[1] = [(PROCESSING_INSTRUCTION, node), None]
 150             self.lastEvent = self.lastEvent[1]
 151         else:
 152             event = [(PROCESSING_INSTRUCTION, target, data), None]
 153             self.pending_events.append(event)
 154
 155     def ignorableWhitespace(self, chars):
 156         node = self.document.createTextNode(chars)
 157         self.lastEvent[1] = [(IGNORABLE_WHITESPACE, node), None]
 158         self.lastEvent = self.lastEvent[1]
 159
 160     def characters(self, chars):
 161         node = self.document.createTextNode(chars)
 162         self.lastEvent[1] = [(CHARACTERS, node), None]
 163         self.lastEvent = self.lastEvent[1]
 164
 165     def startDocument(self):
 166         if self.documentFactory is None:
 167             import xmlcore.dom.minidom
 168             self.documentFactory = xmlcore.dom.minidom.Document.implementation
 169
 170     def buildDocument(self, uri, tagname):
 171         # Can't do that in startDocument, since we need the tagname
 172         # XXX: obtain DocumentType
 173         node = self.documentFactory.createDocument(uri, tagname, None)
 174         self.document = node
 175         self.lastEvent[1] = [(START_DOCUMENT, node), None]
 176         self.lastEvent = self.lastEvent[1]
 177         self.push(node)
 178         # Put everything we have seen so far into the document
 179         for e in self.pending_events:
 180             if e[0][0] == PROCESSING_INSTRUCTION:
 181                 _,target,data = e[0]
 182                 n = self.document.createProcessingInstruction(target, data)
 183                 e[0] = (PROCESSING_INSTRUCTION, n)
 184             elif e[0][0] == COMMENT:
 185                 n = self.document.createComment(e[0][1])
 186                 e[0] = (COMMENT, n)
 187             else:
 188                 raise AssertionError("Unknown pending event ",e[0][0])
 189             self.lastEvent[1] = e
 190             self.lastEvent = e
 191         self.pending_events = None
 192         return node.firstChild
 193
 194     def endDocument(self):
 195         self.lastEvent[1] = [(END_DOCUMENT, self.document), None]
 196         self.pop()
 197
 198     def clear(self):
 199         "clear(): Explicitly release parsing structures"
 200         self.document = None
 201
 202 class ErrorHandler:
 203     def warning(self, exception):
 204         print exception
 205     def error(self, exception):
 206         raise exception
 207     def fatalError(self, exception):
 208         raise exception
 209
 210 class DOMEventStream:
 211     def __init__(self, stream, parser, bufsize):
 212         self.stream = stream
 213         self.parser = parser
 214         self.bufsize = bufsize
 215         if not hasattr(self.parser, 'feed'):
 216             self.getEvent = self._slurp
 217         self.reset()
 218
 219     def reset(self):
 220         self.pulldom = PullDOM()
 221         # This content handler relies on namespace support
 222         self.parser.setFeature(xmlcore.sax.handler.feature_namespaces, 1)
 223         self.parser.setContentHandler(self.pulldom)
 224
 225     def __getitem__(self, pos):
 226         rc = self.getEvent()
 227         if rc:
 228             return rc
 229         raise IndexError
 230
 231     def next(self):
 232         rc = self.getEvent()
 233         if rc:
 234             return rc
 235         raise StopIteration
 236
 237     def __iter__(self):
 238         return self
 239
 240     def expandNode(self, node):
 241         event = self.getEvent()
 242         parents = [node]
 243         while event:
 244             token, cur_node = event
 245             if cur_node is node:
 246                 return
 247             if token != END_ELEMENT:
 248                 parents[-1].appendChild(cur_node)
 249             if token == START_ELEMENT:
 250                 parents.append(cur_node)
 251             elif token == END_ELEMENT:
 252                 del parents[-1]
 253             event = self.getEvent()
 254
 255     def getEvent(self):
 256         # use IncrementalParser interface, so we get the desired
 257         # pull effect
 258         if not self.pulldom.firstEvent[1]:
 259             self.pulldom.lastEvent = self.pulldom.firstEvent
 260         while not self.pulldom.firstEvent[1]:
 261             buf = self.stream.read(self.bufsize)
 262             if not buf:
 263                 self.parser.close()
 264                 return None
 265             self.parser.feed(buf)
 266         rc = self.pulldom.firstEvent[1][0]
 267         self.pulldom.firstEvent[1] = self.pulldom.firstEvent[1][1]
 268         return rc
 269
 270     def _slurp(self):
 271         """ Fallback replacement for getEvent() using the
 272             standard SAX2 interface, which means we slurp the
 273             SAX events into memory (no performance gain, but
 274             we are compatible to all SAX parsers).
 275         """
 276         self.parser.parse(self.stream)
 277         self.getEvent = self._emit
 278         return self._emit()
 279
 280     def _emit(self):
 281         """ Fallback replacement for getEvent() that emits
 282             the events that _slurp() read previously.
 283         """
 284         rc = self.pulldom.firstEvent[1][0]
 285         self.pulldom.firstEvent[1] = self.pulldom.firstEvent[1][1]
 286         return rc
 287
 288     def clear(self):
 289         """clear(): Explicitly release parsing objects"""
 290         self.pulldom.clear()
 291         del self.pulldom
 292         self.parser = None
 293         self.stream = None
 294
 295 class SAX2DOM(PullDOM):
 296
 297     def startElementNS(self, name, tagName , attrs):
 298         PullDOM.startElementNS(self, name, tagName, attrs)
 299         curNode = self.elementStack[-1]
 300         parentNode = self.elementStack[-2]
 301         parentNode.appendChild(curNode)
 302
 303     def startElement(self, name, attrs):
 304         PullDOM.startElement(self, name, attrs)
 305         curNode = self.elementStack[-1]
 306         parentNode = self.elementStack[-2]
 307         parentNode.appendChild(curNode)
 308
 309     def processingInstruction(self, target, data):
 310         PullDOM.processingInstruction(self, target, data)
 311         node = self.lastEvent[0][1]
 312         parentNode = self.elementStack[-1]
 313         parentNode.appendChild(node)
 314
 315     def ignorableWhitespace(self, chars):
 316         PullDOM.ignorableWhitespace(self, chars)
 317         node = self.lastEvent[0][1]
 318         parentNode = self.elementStack[-1]
 319         parentNode.appendChild(node)
 320
 321     def characters(self, chars):
 322         PullDOM.characters(self, chars)
 323         node = self.lastEvent[0][1]
 324         parentNode = self.elementStack[-1]
 325         parentNode.appendChild(node)
 326
 327
 328 default_bufsize = (2 ** 14) - 20
 329
 330 def parse(stream_or_string, parser=None, bufsize=None):
 331     if bufsize is None:
 332         bufsize = default_bufsize
 333     if type(stream_or_string) in _StringTypes:
 334         stream = open(stream_or_string)
 335     else:
 336         stream = stream_or_string
 337     if not parser:
 338         parser = xmlcore.sax.make_parser()
 339     return DOMEventStream(stream, parser, bufsize)
 340
 341 def parseString(string, parser=None):
 342     try:
 343         from cStringIO import StringIO
 344     except ImportError:
 345         from StringIO import StringIO
 346
 347     bufsize = len(string)
 348     buf = StringIO(string)
 349     if not parser:
 350         parser = xmlcore.sax.make_parser()
 351     return DOMEventStream(buf, parser, bufsize)