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module Data.Encoding.ISO2022 where
import Data.Encoding.Base
import Data.Encoding.ByteSource
import Data.Encoding.ByteSink
import Data.Encoding.Exception
import Data.Encoding.ASCII
import Data.Word
import Control.Throws
class ISO2022 e where
readEscape :: ByteSource m => e -> m (Maybe DynEncoding)
encodingForChar :: e -> Char -> Maybe (DynEncoding,[Word8])
encodeCharISO2022 :: (ISO2022 e,ByteSink m) => e -> Char -> m ()
encodeCharISO2022 e c = case encodingForChar e c of
Nothing -> throwException (HasNoRepresentation c)
Just (enc,esc) -> do
mapM_ pushWord8 esc
encodeChar enc c
decodeCharISO2022 :: (ISO2022 e,ByteSource m) => e -> m Char
decodeCharISO2022 e = do
enc <- readEscape e
case enc of
Nothing -> decodeChar ASCII
Just renc -> decodeChar renc
encodeISO2022 :: (ISO2022 e,ByteSink m) => e -> String -> m ()
encodeISO2022 e = encode' (DynEncoding ASCII)
where
encode' _ [] = return ()
encode' enc (c:cs) = case encodingForChar e c of
Nothing -> throwException (HasNoRepresentation c)
Just (nenc,esc)
| enc==nenc -> do
encodeChar enc c
encode' enc cs
| otherwise -> do
mapM_ pushWord8 esc
encodeChar nenc c
encode' nenc cs
decodeISO2022 :: (ISO2022 e,ByteSource m) => e -> m String
decodeISO2022 e = decode' (DynEncoding ASCII)
where
decode' enc = do
empty <- sourceEmpty
if empty
then return []
else (do
nenc <- readEscape e
case nenc of
Just renc -> decode' renc
Nothing -> do
c <- decodeChar enc
cs <- decode' enc
return (c:cs)
)
|
