Generating all permutations from a regexp

[BJörn Lindqvist]

With regexps you can search for strings matching it. For example,
given the regexp: "foobar\d\d\d". "foobar123" would match. I want to
do the reverse, from a regexp generate all strings that could match
it.

The regexp: "[A-Z]{3}\d{3}" should generate the strings "AAA000",
"AAA001", "AAA002" ... "AAB000", "AAB001" ... "ZZZ999".

Is this possible to do? Obviously, for some regexps the set of matches
is unbounded (a list of everything that matches "*" would be very
unpractical), but how would you do it for simple regexps like the one
above?

-- 
mvh Björn