On Tue, Nov 4, 2008 at 6:44 PM, i wrote:

i'm sorry if this is obviously wrong (i haven't used Text.Regex), but can't you do this with submatches?

rights or wrongs of regexps aside, i just checked that the above approach *is* feasible with Text.Regex here's some code:

module Multimatch(multimatch) where import Text.Regex import qualified Data.List as DL import qualified Data.Maybe as DM

brcount :: String -> Int brcount ('\\' : _ : s) = brcount s brcount ('(' : s) = 1 + brcount s brcount (_ : s) = brcount s brcount [] = 0

-- given a list of strings representing regular expressions, -- each associated with a tag, match against a string -- and return the match, along with the associated tag, -- or Nothing if there's no match. multimatch :: [(tag, String)] -> (String -> Maybe (tag, String)) multimatch rs = let re = mkRegex $ DL.intercalate "|" $ map ((\s -> "(x(" ++ s ++ "))") . snd) rs in let tags = submatches rs in (\ s -> do ms <- matchRegex re ("x" ++ s) (tag, m) <- DL.find (\(_, m) -> not (null m)) (zip tags ms) return (DM.fromJust tag, tail m)) submatches [] = [] submatches ((tag, r) : rs) = (Just tag : take (brcount r + 1) (repeat Nothing)) ++ submatches rs

i'm sure there's a more compact implementation in there somewhere: i'm just a haskell newbie. cheers, rog.