Need Regular Expression Parser

[LUMIN@AppleLink.Apple.COM (Lumin, Philip Hainline,PAS)]

Hello!
 
I'm looking for an implementation of a regular expression parser which matches
against strings.  Alternatively, I could make do with a file-searching utility
which provides FULL regular expression capability (i.e. a true GREP
implementation).  I'd even settle for a non-MCL LISP implementation of either
of the above, which I will port, and send you back the ported code.
 
I'd really appreciate any pointers on this.  I *KNOW* that a LISP
implementation of a regular expression parser exists out there, and so I've
really avoided implementing my own.
 
Thanks for ANY info!
Beth Marvel
Lumin Co.