filter_raw_string is a raw string "^(?P<constant>%(constant)s)|^(?P<var>[%(var_chars)s]+|%(num)s)| (?:\s*%(filter_sep)s\s*
filter_raw_string = r""" ^(?P<constant>%(constant)s)| ^(?P<var>[%(var_chars)s]+|%(num)s)| (?:\s*%(filter_sep)s\s* (?P<filter_name>\w+) (?:%(arg_sep)s (?: (?P<constant_arg>%(constant)s)| (?P<var_arg>[%(var_chars)s]+|%(num)s) ) )? )""" % { 'constant' : constant_string , 'num' : r'[-+\.]?\d[\d\.e]*' , 'var_chars' : "\w\." , 'filter_sep' : re . escape ( FILTER_SEPARATOR ) , 'arg_sep' : re . escape ( FILTER_ARGUMENT_SEPARATOR ) , }