ElementTree.py 文件源码

def __init__(self, html=0, target=None, encoding=None):
        try:
            from xml.parsers import expat
        except ImportError:
            try:
                import pyexpat as expat
            except ImportError:
                raise ImportError(
                    "No module named expat; use SimpleXMLTreeBuilder instead"
                    )
        parser = expat.ParserCreate(encoding, "}")
        if target is None:
            target = TreeBuilder()
        # underscored names are provided for compatibility only
        self.parser = self._parser = parser
        self.target = self._target = target
        self._error = expat.error
        self._names = {} # name memo cache
        # callbacks
        parser.DefaultHandlerExpand = self._default
        parser.StartElementHandler = self._start
        parser.EndElementHandler = self._end
        parser.CharacterDataHandler = self._data
        # optional callbacks
        parser.CommentHandler = self._comment
        parser.ProcessingInstructionHandler = self._pi
        # let expat do the buffering, if supported
        try:
            self._parser.buffer_text = 1
        except AttributeError:
            pass
        # use new-style attribute handling, if supported
        try:
            self._parser.ordered_attributes = 1
            self._parser.specified_attributes = 1
            parser.StartElementHandler = self._start_list
        except AttributeError:
            pass
        self._doctype = None
        self.entity = {}
        try:
            self.version = "Expat %d.%d.%d" % expat.version_info
        except AttributeError:
            pass # unknown