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# XML parsing
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import re
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import xml.dom.minidom as minidom
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import xml.parsers.expat as expat
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import exc
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import streams
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import strings
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def parse_str(str_): return minidom.parseString(str_).documentElement
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class ConsecXmlInputStream(streams.TracedStream):
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    '''Wraps an input stream, inserting EOF after each consecutive XML document
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    '''
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    def __init__(self, stream):
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        self.eof = False
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        self.root_close_tag = None
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        def trace(line):
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            if self.root_close_tag == None: # before XML document
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                match = re.match(r'^<(?!\?)([^\s>]+)', line)
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                if match: self.root_close_tag = '</'+match.group(1)+'>'
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            else: # inside XML document
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                if line.rstrip().endswith(self.root_close_tag):
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                    self.root_close_tag = None # now outside XML document
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                    self.eof = True # next read will produce EOF
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        streams.TracedStream.__init__(self, trace, stream)
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    def readline(self):
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        if self.eof:
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            self.eof = False
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            return '' # don't read from underlying stream
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        else: return streams.TracedStream.readline(self)
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def parse_next(stream, on_error=exc.raise_):
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    '''Parses the next document in a consecutive sequence of XML documents.
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    @return The next document's root, or None if no more documents available
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    '''
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    try: return minidom.parse(streams.FilterStream(strings.strip_ctrl,
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        ConsecXmlInputStream(stream))).documentElement
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    except expat.ExpatError, e:
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        # Save in case another exception raised, overwriting sys.exc_info()
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        exc.add_traceback(e)
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        if str(e).startswith('no element found:'): return None # no more docs
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        else: # parser error, which corrupts the rest of the current document
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            on_error(e)
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            streams.consume(stream) # advance to next XML document
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def docs_iter(stream, *args, **kw_args):
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    return iter(lambda: parse_next(stream, *args, **kw_args), None)
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