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pulldom.py
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import xml.sax import xml.sax.handler START_ELEMENT = "START_ELEMENT" END_ELEMENT = "END_ELEMENT" COMMENT = "COMMENT" START_DOCUMENT = "START_DOCUMENT" END_DOCUMENT = "END_DOCUMENT" PROCESSING_INSTRUCTION = "PROCESSING_INSTRUCTION" IGNORABLE_WHITESPACE = "IGNORABLE_WHITESPACE" CHARACTERS = "CHARACTERS" class PullDOM(xml.sax.ContentHandler): _locator = None document = None def __init__(self, documentFactory=None): from xml.dom import XML_NAMESPACE self.documentFactory = documentFactory self.firstEvent = [None, None] self.lastEvent = self.firstEvent self.elementStack = [] self.push = self.elementStack.append try: self.pop = self.elementStack.pop except AttributeError: # use class' pop instead pass self._ns_contexts = [{XML_NAMESPACE:'xml'}] # contains uri -> prefix dicts self._current_context = self._ns_contexts[-1] self.pending_events = [] def pop(self): result = self.elementStack[-1] del self.elementStack[-1] return result def setDocumentLocator(self, locator): self._locator = locator def startPrefixMapping(self, prefix, uri): if not hasattr(self, '_xmlns_attrs'): self._xmlns_attrs = [] self._xmlns_attrs.append((prefix or 'xmlns', uri)) self._ns_contexts.append(self._current_context.copy()) self._current_context[uri] = prefix or None def endPrefixMapping(self, prefix): self._current_context = self._ns_contexts.pop() def startElementNS(self, name, tagName , attrs): # Retrieve xml namespace declaration attributes. xmlns_uri = 'http://www.w3.org/2000/xmlns/' xmlns_attrs = getattr(self, '_xmlns_attrs', None) if xmlns_attrs is not None: for aname, value in xmlns_attrs: attrs._attrs[(xmlns_uri, aname)] = value self._xmlns_attrs = [] uri, localname = name if uri: # When using namespaces, the reader may or may not # provide us with the original name. If not, create # *a* valid tagName from the current context. if tagName is None: prefix = self._current_context[uri] if prefix: tagName = prefix + ":" + localname else: tagName = localname if self.document: node = self.document.createElementNS(uri, tagName) else: node = self.buildDocument(uri, tagName) else: # When the tagname is not prefixed, it just appears as # localname if self.document: node = self.document.createElement(localname) else: node = self.buildDocument(None, localname) for aname,value in attrs.items(): a_uri, a_localname = aname if a_uri == xmlns_uri: if a_localname == 'xmlns': qname = a_localname else: qname = 'xmlns:' + a_localname attr = self.document.createAttributeNS(a_uri, qname) node.setAttributeNodeNS(attr) elif a_uri: prefix = self._current_context[a_uri] if prefix: qname = prefix + ":" + a_localname else: qname = a_localname attr = self.document.createAttributeNS(a_uri, qname) node.setAttributeNodeNS(attr) else: attr = self.document.createAttribute(a_localname) node.setAttributeNode(attr) attr.value = value self.lastEvent[1] = [(START_ELEMENT, node), None] self.lastEvent = self.lastEvent[1] self.push(node) def endElementNS(self, name, tagName): self.lastEvent[1] = [(END_ELEMENT, self.pop()), None] self.lastEvent = self.lastEvent[1] def startElement(self, name, attrs): if self.document: node = self.document.createElement(name) else: node = self.buildDocument(None, name) for aname,value in attrs.items(): attr = self.document.createAttribute(aname) attr.value = value node.setAttributeNode(attr) self.lastEvent[1] = [(START_ELEMENT, node), None] self.lastEvent = self.lastEvent[1] self.push(node) def endElement(self, name): self.lastEvent[1] = [(END_ELEMENT, self.pop()), None] self.lastEvent = self.lastEvent[1] def comment(self, s): if self.document: node = self.document.createComment(s) self.lastEvent[1] = [(COMMENT, node), None] self.lastEvent = self.lastEvent[1] else: event = [(COMMENT, s), None] self.pending_events.append(event) def processingInstruction(self, target, data): if self.document: node = self.document.createProcessingInstruction(target, data) self.lastEvent[1] = [(PROCESSING_INSTRUCTION, node), None] self.lastEvent = self.lastEvent[1] else: event = [(PROCESSING_INSTRUCTION, target, data), None] self.pending_events.append(event) def ignorableWhitespace(self, chars): node = self.document.createTextNode(chars) self.lastEvent[1] = [(IGNORABLE_WHITESPACE, node), None] self.lastEvent = self.lastEvent[1] def characters(self, chars): node = self.document.createTextNode(chars) self.lastEvent[1] = [(CHARACTERS, node), None] self.lastEvent = self.lastEvent[1] def startDocument(self): if self.documentFactory is None: import xml.dom.minidom self.documentFactory = xml.dom.minidom.Document.implementation def buildDocument(self, uri, tagname): # Can't do that in startDocument, since we need the tagname # XXX: obtain DocumentType node = self.documentFactory.createDocument(uri, tagname, None) self.document = node self.lastEvent[1] = [(START_DOCUMENT, node), None] self.lastEvent = self.lastEvent[1] self.push(node) # Put everything we have seen so far into the document for e in self.pending_events: if e[0][0] == PROCESSING_INSTRUCTION: _,target,data = e[0] n = self.document.createProcessingInstruction(target, data) e[0] = (PROCESSING_INSTRUCTION, n) elif e[0][0] == COMMENT: n = self.document.createComment(e[0][1]) e[0] = (COMMENT, n) else: raise AssertionError("Unknown pending event ",e[0][0]) self.lastEvent[1] = e self.lastEvent = e self.pending_events = None return node.firstChild def endDocument(self): self.lastEvent[1] = [(END_DOCUMENT, self.document), None] self.pop() def clear(self): "clear(): Explicitly release parsing structures" self.document = None class ErrorHandler: def warning(self, exception): print(exception) def error(self, exception): raise exception def fatalError(self, exception): raise exception class DOMEventStream: def __init__(self, stream, parser, bufsize): self.stream = stream self.parser = parser self.bufsize = bufsize if not hasattr(self.parser, 'feed'): self.getEvent = self._slurp self.reset() def reset(self): self.pulldom = PullDOM() # This content handler relies on namespace support self.parser.setFeature(xml.sax.handler.feature_namespaces, 1) self.parser.setContentHandler(self.pulldom) def __getitem__(self, pos): import warnings warnings.warn( "DOMEventStream's __getitem__ method ignores 'pos' parameter. " "Use iterator protocol instead.", DeprecationWarning, stacklevel=2 ) rc = self.getEvent() if rc: return rc raise IndexError def __next__(self): rc = self.getEvent() if rc: return rc raise StopIteration def __iter__(self): return self def expandNode(self, node): event = self.getEvent() parents = [node] while event: token, cur_node = event if cur_node is node: return if token != END_ELEMENT: parents[-1].appendChild(cur_node) if token == START_ELEMENT: parents.append(cur_node) elif token == END_ELEMENT: del parents[-1] event = self.getEvent() def getEvent(self): # use IncrementalParser interface, so we get the desired # pull effect if not self.pulldom.firstEvent[1]: self.pulldom.lastEvent = self.pulldom.firstEvent while not self.pulldom.firstEvent[1]: buf = self.stream.read(self.bufsize) if not buf: self.parser.close() return None self.parser.feed(buf) rc = self.pulldom.firstEvent[1][0] self.pulldom.firstEvent[1] = self.pulldom.firstEvent[1][1] return rc def _slurp(self): """ Fallback replacement for getEvent() using the standard SAX2 interface, which means we slurp the SAX events into memory (no performance gain, but we are compatible to all SAX parsers). """ self.parser.parse(self.stream) self.getEvent = self._emit return self._emit() def _emit(self): """ Fallback replacement for getEvent() that emits the events that _slurp() read previously. """ rc = self.pulldom.firstEvent[1][0] self.pulldom.firstEvent[1] = self.pulldom.firstEvent[1][1] return rc def clear(self): """clear(): Explicitly release parsing objects""" self.pulldom.clear() del self.pulldom self.parser = None self.stream = None class SAX2DOM(PullDOM): def startElementNS(self, name, tagName , attrs): PullDOM.startElementNS(self, name, tagName, attrs) curNode = self.elementStack[-1] parentNode = self.elementStack[-2] parentNode.appendChild(curNode) def startElement(self, name, attrs): PullDOM.startElement(self, name, attrs) curNode = self.elementStack[-1] parentNode = self.elementStack[-2] parentNode.appendChild(curNode) def processingInstruction(self, target, data): PullDOM.processingInstruction(self, target, data) node = self.lastEvent[0][1] parentNode = self.elementStack[-1] parentNode.appendChild(node) def ignorableWhitespace(self, chars): PullDOM.ignorableWhitespace(self, chars) node = self.lastEvent[0][1] parentNode = self.elementStack[-1] parentNode.appendChild(node) def characters(self, chars): PullDOM.characters(self, chars) node = self.lastEvent[0][1] parentNode = self.elementStack[-1] parentNode.appendChild(node) default_bufsize = (2 ** 14) - 20 def parse(stream_or_string, parser=None, bufsize=None): if bufsize is None: bufsize = default_bufsize if isinstance(stream_or_string, str): stream = open(stream_or_string, 'rb') else: stream = stream_or_string if not parser: parser = xml.sax.make_parser() return DOMEventStream(stream, parser, bufsize) def parseString(string, parser=None): from io import StringIO bufsize = len(string) buf = StringIO(string) if not parser: parser = xml.sax.make_parser() return DOMEventStream(buf, parser, bufsize)