Elegant way to parse arguments, keyword arguments and/or return variable for a django template tag

gistfile1.py

def do_sometag(parser, token):
    """
    {% tagname arg1 arg2 arg3 ... with kwg1=v kwg2=v kwg3=v ... as varname %}
    """

    argv = token.contents.split()
    
    # get the index of 'as' or the total length of the arguments
    a = 'as' in argv and argv.index('as') or len(argv)
    # get the index from 'with' to 'as' or the total length of arguments
    e = 'with' in argv and argv.index('with') or a
    
    # the path args are from the object to either 'with', 'as' or length of arguments
    path_args = argv[1: e]
    # extra args are from 'with' to 'as' or to length of arguments
    extra_args = argv[e+1: a]
    # the varname is the last element of the list if 'as' is present
    varname = argv[a:] and argv[a+1] or None
    
    # split the extra args by '=' and make a dict
    extra_kwgs = dict([(x.split("=")[0],x.split("=")[1]) for x in extra_args if '=' in x])
    
    # do other processing..