Regexp problem for gurus

[Pekka Niiranen]

How can I make python to return list of matches in the following case:

The searched texts are between ?- and ! -signs
Different start (?) and end (!) -signs are used in order to able
to detect nested matches.

case 1:        Line = "aaa?HHH!bbb?JJJJ!ccc?KKKK!dddd
                   Returned list should be:
                       ?HHH!, ?JJJJ!, ?KKKK!

                   For this one I allready know the answer:

                   pattern = re.compile(r'?[^?!]+!')
                   list = re.findall(pattern, Line)

case 2:        Line = "aaa?HHHbbb?JJJJ!ccc!?KKKK!dddd
                   Returned list should be (the order of matches does
not matter):
                       ?HHHbbb?JJJJ!ccc!, ?JJJJ!, ?KKKK!

                    In this case ?JJJJ! is nested inside
?HHHbbb?JJJJ!ccc!
                    The amount of nested patterns is limited by the
python ?

Is it possible to compile a single regular expression that covers both
the cases ?
Howabout if the limiting signs consist more than one characters
(not ? and !, but <?> and <!>)? Then negation group [^] would not work ?

-pekka-