Perhaps a FAQ: How to shortcut an alternation if one already commited subrule fails

[Karl Gaissmaier]

Hi P::RD lovers,

is there a general advice to shortcut an alternation in a rule
if one already commited subrule fails:
Example:

ENTITY : ( COMMENT | OPTION | DECLARATION | SCOPE )(s)

COMMENT : '#' <commit> m/.*/
          | <error?> <reject>
OPTION  : IDENT '=' <commit> VALUE
          { store($item{IDENT}, $item{VALUE}) }
          | <error?> <reject>
DECL    : TYPE NAME '{' <commit> DECL_BODY '}'
          { store($item{TYPE}, $ITEM{NAME}, $ITEM{DECL_BODY}) }
          | <error?> <reject>
SCOPE   : 'scope' <commit> '{' ENTITY(s) '}'
          | <error?> <reject>
I would like to see the immediately failure of ENTITY, if
e.g. the DECL subrule fails after already commited.
Is there a general usage pattern to shortcut the ENTITY rule
if an already commited subrule fails?
Best Regards
        Charly
--
Karl Gaissmaier       KIZ/Infrastructure, University of Ulm, Germany
Email:[EMAIL PROTECTED]           Service Group Network
Tel.: ++49 731 50-22499