Unicode.hs

{-
  Copyright (C) 2009 John Millikin <jmillikin@gmail.com>
  
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  any later version.
  
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-}

module DBus.Wire.Unicode
        ( maybeEncodeUtf8
        , maybeDecodeUtf8) where
import Data.ByteString.Lazy (ByteString)
import Data.Text.Lazy (Text)
import Data.Text.Lazy.Encoding (encodeUtf8, decodeUtf8)
import Data.Text.Encoding.Error (UnicodeException)
import qualified Control.Exception as Exc
import System.IO.Unsafe (unsafePerformIO)

excToMaybe :: a -> Maybe a
excToMaybe x = unsafePerformIO $ fmap Just (Exc.evaluate x) `Exc.catch` unicodeError

unicodeError :: UnicodeException -> IO (Maybe a)
unicodeError = const $ return Nothing

maybeEncodeUtf8 :: Text -> Maybe ByteString
maybeEncodeUtf8 = excToMaybe . encodeUtf8

maybeDecodeUtf8 :: ByteString -> Maybe Text
maybeDecodeUtf8 = excToMaybe . decodeUtf8