Can haproxy ACL on cookie -contents-?

[Dave Shevett]

I've seen a couple posts (here and on stackoverflow) on checking to see
if a cookie exists, and setting an ACL based on that, but not what value
it has.

Am I going to need to use a regexp to parse a header cookie line?  (I
want to say 'if a cookie has value x, use backend x, if it has value y,
use backend y).

Thanks!

    -d