module Distribution.ReadE (
ReadE(..), succeedReadE, failReadE,
parsecToReadE, parsecToReadEErr,
unexpectMsgString,
) where
import Distribution.Compat.Prelude
import Prelude ()
import qualified Data.Bifunctor as Bi (first)
import Distribution.Parsec
import qualified Text.Parsec.Error as Parsec
import Distribution.Parsec.FieldLineStream
newtype ReadE a = ReadE {runReadE :: String -> Either ErrorMsg a}
type ErrorMsg = String
instance Functor ReadE where
fmap f (ReadE p) = ReadE $ \txt -> case p txt of
Right a -> Right (f a)
Left err -> Left err
succeedReadE :: (String -> a) -> ReadE a
succeedReadE f = ReadE (Right . f)
failReadE :: ErrorMsg -> ReadE a
failReadE = ReadE . const . Left
runParsecFromString :: ParsecParser a -> String -> Either Parsec.ParseError a
runParsecFromString p txt =
runParsecParser p "<parsecToReadE>" (fieldLineStreamFromString txt)
parsecToReadE :: (String -> ErrorMsg) -> ParsecParser a -> ReadE a
parsecToReadE err p = ReadE $ \txt ->
(const $ err txt) `Bi.first` runParsecFromString p txt
parsecToReadEErr :: (Parsec.ParseError -> ErrorMsg) -> ParsecParser a -> ReadE a
parsecToReadEErr err p = ReadE $
Bi.first err . runParsecFromString p
unexpectMsgString :: Parsec.ParseError -> String
unexpectMsgString = unlines
. map Parsec.messageString
. filter (\case { Parsec.UnExpect _ -> True; _ -> False })
. Parsec.errorMessages