This would've been more interesting if it weren't confined to the start of the string. And by "interesting", I mean it would have presented an opportunity to showcase forced backtracking in a regex among some of the other powerful things regexes can do.
Jeff japhy Pinyan,
P.L., P.M., P.O.D, X.S.:
Perl,
regex,
and perlhacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart