Lib/xml/dom/pulldom.py

import minidom
import xml.sax

#todo: SAX2/namespace handling

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:
    def __init__(self):
        self.firstEvent = [None, None]
        self.lastEvent = self.firstEvent

    def setDocumentLocator(self, locator): pass

    def startElement(self, name, tagName, attrs):
        if not hasattr(self, "curNode"):
            # FIXME: hack!
            self.startDocument()

        node = self.document.createElement(tagName) #FIXME namespaces!
        for attr in attrs.keys():
            node.setAttribute(attr, attrs[attr])

        parent = self.curNode
        node.parentNode = parent
        if parent.childNodes:
            node.previousSibling = parent.childNodes[-1]
            node.previousSibling.nextSibling = node
        self.curNode = node
        # FIXME: do I have to screen namespace attributes
        self.lastEvent[1] = [(START_ELEMENT, node), None]
        self.lastEvent = self.lastEvent[1]
        #self.events.append((START_ELEMENT, node))

    def endElement(self, name, tagName):
        node = self.curNode
        self.lastEvent[1] = [(END_ELEMENT, node), None]
        self.lastEvent = self.lastEvent[1]
        #self.events.append((END_ELEMENT, node))
        self.curNode = node.parentNode

    def comment(self, s):
        node = self.document.createComment(s)
        parent = self.curNode
        node.parentNode = parent
        if parent.childNodes:
            node.previousSibling = parent.childNodes[-1]
            node.previousSibling.nextSibling = node
        self.lastEvent[1] = [(COMMENT, node), None]
        self.lastEvent = self.lastEvent[1]
        #self.events.append((COMMENT, node))

    def processingInstruction(self, target, data):
        node = self.document.createProcessingInstruction(target, data)
        #self.appendChild(node)
        
        parent = self.curNode
        node.parentNode = parent
        if parent.childNodes:
            node.previousSibling = parent.childNodes[-1]
            node.previousSibling.nextSibling = node
        self.lastEvent[1] = [(PROCESSING_INSTRUCTION, node), None]
        self.lastEvent = self.lastEvent[1]
        #self.events.append((PROCESSING_INSTRUCTION, node))

    def ignorableWhitespace(self, chars):
        node = self.document.createTextNode(chars[start:start + length])
        parent = self.curNode
        node.parentNode = parent
        if parent.childNodes:
            node.previousSibling = parent.childNodes[-1]
            node.previousSibling.nextSibling = node
        self.lastEvent[1] = [(IGNORABLE_WHITESPACE, node), None]
        self.lastEvent = self.lastEvent[1]
        #self.events.append((IGNORABLE_WHITESPACE, node))

    def characters(self, chars):
        node = self.document.createTextNode(chars)
        node.parentNode = self.curNode
        self.lastEvent[1] = [(CHARACTERS, node), None]
        self.lastEvent = self.lastEvent[1]

    def startDocument(self):
        node = self.curNode = self.document = minidom.Document()
        node.parentNode = None
        self.lastEvent[1] = [(START_DOCUMENT, node), None]
        self.lastEvent = self.lastEvent[1]
        #self.events.append((START_DOCUMENT, node))

    def endDocument(self):
        assert not self.curNode.parentNode
        for node in self.curNode.childNodes:
            if node.nodeType == node.ELEMENT_NODE:
                self.document.documentElement = node
        #if not self.document.documentElement:
        #    raise Error, "No document element"

        self.lastEvent[1] = [(END_DOCUMENT, node), None]
        #self.events.append((END_DOCUMENT, self.curNode))

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
        self.reset()

    def reset(self):
        self.pulldom = PullDOM()
        self.parser.setContentHandler(self.pulldom)

    def __getitem__(self, pos):
        rc = self.getEvent()
        if rc:
            return rc
        raise IndexError

    def expandNode(self, node):
        event = self.getEvent()
        while event:
            token, cur_node = event
            if cur_node is node:
                return
            if token != END_ELEMENT:
                cur_node.parentNode.appendChild(cur_node)
            event = self.getEvent()

    def getEvent(self):
        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:
                #FIXME: why doesn't Expat close work?
                #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

# FIXME: sax2
#def _getParser( ):
 #   from xml.sax.saxexts import make_parser
    # expat doesn't report errors properly! Figure it out
  #  return make_parser()
   # return make_parser("xml.sax.drivers.drv_xmllib")


        
def _getParser():
     return xml.sax.make_parser()

default_bufsize = (2 ** 14) - 20

# FIXME: move into sax package for common usage
def parse(stream_or_string, parser=None, bufsize=default_bufsize):
    if type(stream_or_string) is type(""):
        stream = open(stream_or_string)
    else:
        stream = stream_or_string
    if not parser: 
        parser = _getParser()
    return DOMEventStream(stream, parser, bufsize)

def parseString(string, parser=None):
    try:
        from cStringIO import StringIO
    except ImportError:
        from StringIO import StringIO
        
    bufsize = len(string)
    buf = StringIO(string)
    parser = _getParser()
    return DOMEventStream(buf, parser, bufsize)