Parse the query component of a URI.

ParseUriQuery.hs

module ParseUriQuery where

import Control.Applicative
import Data.Attoparsec.ByteString.Char8
import Data.ByteString.Char8 (ByteString, pack, unpack)
import Data.Either

data QueryTerm = QueryTerm { termName  :: ByteString
                           , termValue :: Maybe ByteString
                           } deriving (Eq, Read, Show)

termList = queryTerm `sepBy` (char '&')
queryTerm = QueryTerm <$> name <*> value
            
name = takeWhile1 notTermSeparator <* discardEqualsSign
  where notTermSeparator = notInClass "&="
        discardEqualsSign = option '=' (char '=')

value = option Nothing nonEmptyValue
  where nonEmptyValue = Just <$> takeWhile1 (/= '&')


-- Convenience function.
runParser :: Parser c -> String -> c
runParser p = head . rights . return . parseOnly p . pack