Serial.hs

-- Copyright: 2007, 2008 Dino Morelli
-- License: BSD3 (see LICENSE)
-- Author: Dino Morelli <dino@ui3.info>

module Photoname.Serial (
   getSerial
)
   where

--import Debug.Trace
import Text.ParserCombinators.Parsec


-- Combinator similar to manyTill, but evaluates to end instead of p
skipTill :: GenParser tok st t1 -> GenParser tok st t -> GenParser tok st t
skipTill p end = scan
   where
      scan = do { end }     -- If end succeeds, return that.
             <|>
             do { p; scan } -- Otherwise, match p and recurse.


serialNum :: GenParser Char st [Char]
serialNum =
   skipTill anyChar $ try $ do  -- Skip anything up to..
      serial <- count 3 digit   -- 3 digits..
      char '.'                  -- followed by a period..
      count 3 alphaNum          -- followed by 3 alphaNumS..
      eof                       -- at the end of the string.
      return serial             -- Return those 3 digits


-- Evaluates one or more parsers trying to find the serial number in the
-- supplied path. Transforms the result from Either to Maybe
getSerial :: FilePath -> Maybe String
getSerial s =
   case (parse parser "" s) of
      Left _  -> Nothing
      --Left err  -> trace (show err) Nothing
      Right x -> Just x
   where
      parser = serialNum