bre.py 文件源码

def iternext(self):
        """
        Iterate through characters of the string.

        Count escaped l, L, c, C, E and backslash as a single char.
        """

        if self.index > self.max_index:
            raise StopIteration

        char = self.string[self.index:self.index + 1]
        if char == self._b_slash:
            m = self._replace_ref.match(self.string[self.index + 1:])
            if m:
                ref = m.group(0)
                if len(ref) == 1 and ref in self._long_replace_refs:
                    if ref == self._hex:
                        raise SyntaxError('Format for byte is \\xXX!')
                    elif ref == self._group:
                        raise SyntaxError('Format for group is \\g<group_name_or_index>!')
                    elif ref == self._unicode_name:
                        raise SyntaxError('Format for Unicode name is \\N{name}!')
                    elif ref == self._unicode_narrow:  # pragma: no cover
                        raise SyntaxError('Format for Unicode is \\uXXXX!')
                    elif ref == self._unicode_wide:  # pragma: no cover
                        raise SyntaxError('Format for wide Unicode is \\UXXXXXXXX!')
                if self.use_format and (m.group(3) or m.group(4)):
                    char += self._b_slash
                    self.index -= 1
                if not self.use_format or not m.group(4):
                    char += m.group(1) if m.group(1) else m.group(2)
        elif self.use_format and char in (self._lc_bracket, self._rc_bracket):
            m = self._format_replace_group.match(self.string[self.index:])
            if m:
                if m.group(2):
                    char = m.group(2)
                else:
                    self.index += 1
            else:
                raise ValueError("Single unmatched curly bracket!")

        self.index += len(char)
        self.current = char
        return self.current