def copy_iterator(self):

        """

        make a fresh copy of generator, we should not iterate thru

        an original as it's needed for repeating operations on

        this instance of DiffProcessor

        """

        self.__udiff, iterator_copy = tee(self.__udiff)

        return iterator_copy

    def _extract_rev(self, line1, line2):

        """

        """

        try:

            if line1.startswith('--- ') and line2.startswith('+++ '):

                l1 = line1[4:].split(None, 1)

                old_filename = (l1[0].replace('a/', '', 1)

                                if len(l1) >= 1 else None)

                old_rev = l1[1] if len(l1) == 2 else 'old'

                l2 = line2[4:].split(None, 1)

                new_filename = (l2[0].replace('b/', '', 1)

                                if len(l1) >= 1 else None)

                new_rev = l2[1] if len(l2) == 2 else 'new'

                filename = (old_filename

                            if old_filename != '/dev/null' else new_filename)

        except (ValueError, IndexError):

            pass

    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)

            do(next_)

    def _parse_udiff(self):

        """

        Parse the diff an return data for the template.

        """

        lineiter = self.lines

        files = []

        try:

            line = lineiter.next()

            # skip first context

            skipfirst = True

            while 1:

                # continue until we found the old file

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

                    line = lineiter.next()

                    continue

                chunks = []

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

                files.append({

                    'filename':         filename,

                    'old_revision':     old_rev,

                    'new_revision':     new_rev,

                })

                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

                    context = len(match.groups()) == 5

                        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)

                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.

    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',

        """

        Return udiff as html table with customized css classes

        """

        def _link_to_if(condition, label, url):

            """

            Generates a link if condition is meet or just the label if not.

            """

            if condition:

                return '''<a href="%(url)s">%(label)s</a>''' % {

                    'url': url,

                    'label': label

                }

            else:

                return label

        diff_lines = self.prepare()

        _html_empty = True

        _html = []

        _html.append('''<table class="%(table_class)s">\n''' % {

            'table_class': table_class

        })

        for diff in diff_lines:

            for line in diff['chunks']:

                _html_empty = False

                for change in line:

                    _html.append('''<tr class="%(lc)s %(action)s">\n''' % {

                        'lc': line_class,