-- ------------------------------------------------------------

{- |

   Module     : Data.String.UTF8Decoding

   Copyright  : Copyright (C) 2010- Uwe Schmidt

   License    : MIT

   Maintainer : Uwe Schmidt (uwe@fh-wedel.de)

   Stability  : stable

   Portability: portable

   Interface for Data.Char.UTF8 funtions

-}

-- ------------------------------------------------------------

module Data.String.UTF8Decoding (

   decodeUtf8,

   decodeUtf8EmbedErrors,

   decodeUtf8IgnoreErrors,

   )

where

import qualified Data.String.UTF8 as UTF8

import           Data.Word (Word8)

-- | calls 'Data.Char.UTF8.decode' for parsing and decoding UTF-8

decodeUtf8      :: String -> (String, [String])

decodeUtf8 str

    = (res, map (uncurry toErrStr) errs)

    where

    (res, errs) = UTF8.decode . stringToByteString $ str

decodeUtf8IgnoreErrors  :: String -> String

decodeUtf8IgnoreErrors

    = fst . decodeUtf8

decodeUtf8EmbedErrors   :: String -> [Either String Char]

decodeUtf8EmbedErrors str

    = map (either (Left . uncurry toErrStr) Right) $

      UTF8.decodeEmbedErrors $ stringToByteString $ str

stringToByteString :: String -> [Word8]

stringToByteString = map (toEnum . fromEnum)

toErrStr :: UTF8.Error -> Int -> String

toErrStr err pos

        = " at input position " ++ show pos ++ ": " ++ show err

-- ------------------------------------------------------------