except (ValueError, IndexError):

            pass

        return None, None, None

    def _parse_gitdiff(self, diffiterator):

        def line_decoder(l):

            if l.startswith('+') and not l.startswith('+++'):

                self.adds += 1

            elif l.startswith('-') and not l.startswith('---'):

                self.removes += 1

            return l.decode('utf8', 'replace')

        output = list(diffiterator)

        size = len(output)

        if size == 2:

            l = []

            l.extend([output[0]])

            l.extend(output[1].splitlines(1))

            return map(line_decoder, l)

        elif size == 1:

            return  map(line_decoder, output[0].splitlines(1))

        elif size == 0:

            return []

        raise Exception('wrong size of diff %s' % size)

    def _highlight_line_difflib(self, line, next_):

        """

        Highlight inline changes in both lines.

        """

        if line['action'] == 'del':

            old, new = line, next_

        else:

            old, new = next_, line

        oldwords = re.split(r'(\W)', old['line'])

        newwords = re.split(r'(\W)', new['line'])

        sequence = difflib.SequenceMatcher(None, oldwords, newwords)

        oldfragments, newfragments = [], []

        for tag, i1, i2, j1, j2 in sequence.get_opcodes():

            oldfrag = ''.join(oldwords[i1:i2])

            newfrag = ''.join(newwords[j1:j2])

            if tag != 'equal':

                if oldfrag:

                    oldfrag = '<del>%s</del>' % oldfrag

                if newfrag:

                    newfrag = '<ins>%s</ins>' % newfrag

            oldfragments.append(oldfrag)

            newfragments.append(newfrag)

        old['line'] = "".join(oldfragments)

        new['line'] = "".join(newfragments)

    def _highlight_line_udiff(self, line, next_):

        """

        Highlight inline changes in both lines.

        """

        start = 0

        limit = min(len(line['line']), len(next_['line']))

        while start < limit and line['line'][start] == next_['line'][start]:

            start += 1

        end = -1

        limit -= start

        while -end <= limit and line['line'][end] == next_['line'][end]:

            end -= 1

        end += 1

        if start or end:

            def do(l):

                last = end + len(l['line'])

                if l['action'] == 'add':

                    tag = 'ins'

                else:

                    tag = 'del'

                l['line'] = '%s<%s>%s</%s>%s' % (

                    l['line'][:start],

                    tag,

                    l['line'][start:last],

                    tag,

                    l['line'][last:]

                )

            do(line)

            do(next_)

    def _parse_udiff(self):

        """

        Parse the diff an return data for the template.

        """

        lineiter = self.lines

        files = []

        try:

            line = lineiter.next()

            while 1:

                # continue until we found the old file

                if not line.startswith('--- '):

                    line = lineiter.next()

                    continue

                chunks = []

                filename, old_rev, new_rev = \

                    self._extract_rev(line, lineiter.next())

                files.append({

                    'filename':         filename,

                    'old_revision':     old_rev,

                    'new_revision':     new_rev,

                    'chunks':           chunks

                })

                line = lineiter.next()

                while line:

                    match = self._chunk_re.match(line)

                    if not match:

                        break

                    lines = []

                    chunks.append(lines)

                    old_line, old_end, new_line, new_end = \

                        [int(x or 1) for x in match.groups()[:-1]]

                    old_line -= 1

                    new_line -= 1

                    old_end += old_line

                    new_end += new_line

                    if context:

                            lines.append({

                                'old_lineno': '...',

                                'new_lineno': '...',

                                'action':     'context',

                                'line':       line,

                            })

                    line = lineiter.next()

                    while old_line < old_end or new_line < new_end:

                        if line:

                            command, line = line[0], line[1:]

                        else:

                            command = ' '

                        affects_old = affects_new = False

                        # ignore those if we don't expect them

                        if command in '#@':

                            continue

                        elif command == '+':

                            affects_new = True

                            action = 'add'

                        elif command == '-':

                            affects_old = True

                            action = 'del'

                        else:

                            affects_old = affects_new = True

                            action = 'unmod'

                        old_line += affects_old

                        new_line += affects_new

                        lines.append({

                            'old_lineno':   affects_old and old_line or '',

                            'new_lineno':   affects_new and new_line or '',

                            'action':       action,

                            'line':         line

                        })

                        line = lineiter.next()

        except StopIteration:

            pass

        # highlight inline changes

        for _ in files:

            for chunk in chunks:

                lineiter = iter(chunk)

                #first = True

                try:

                    while 1:

                        line = lineiter.next()

                        if line['action'] != 'unmod':

                            nextline = lineiter.next()

                            if nextline['action'] == 'unmod' or \

                               nextline['action'] == line['action']:

                                continue

                            self.differ(line, nextline)

                except StopIteration:

                    pass

        return files

    def prepare(self):

        """

        Prepare the passed udiff for HTML rendering. It'l return a list

        of dicts

        """

        return self._parse_udiff()

    def _safe_id(self, idstring):

        """Make a string safe for including in an id attribute.

        The HTML spec says that id attributes 'must begin with

        a letter ([A-Za-z]) and may be followed by any number

        of letters, digits ([0-9]), hyphens ("-"), underscores

        ("_"), colons (":"), and periods (".")'. These regexps

        are slightly over-zealous, in that they remove colons

        and periods unnecessarily.

        Whitespace is transformed into underscores, and then

        anything which is not a hyphen or a character that

        matches \w (alphanumerics and underscore) is removed.

        """

        # Transform all whitespace to underscore

        idstring = re.sub(r'\s', "_", '%s' % idstring)

        # Remove everything that is not a hyphen or a member of \w

        idstring = re.sub(r'(?!-)\W', "", idstring).lower()

        return idstring

    def raw_diff(self):

        """

        Returns raw string as udiff

        """

        udiff_copy = self.copy_iterator()

        if self.__format == 'gitdiff':

            udiff_copy = self._parse_gitdiff(udiff_copy)

        return u''.join(udiff_copy)

    def as_html(self, table_class='code-difftable', line_class='line',

                new_lineno_class='lineno old', old_lineno_class='lineno new',

                code_class='code', enable_comments=False):

        """

        Return udiff as html table with customized css classes

        """

        def _link_to_if(condition, label, url):