7f65298d3a
Ignore-this: 6058e1ef5776d1cdf70c32e533252b5e darcs-hash:20090303125452-a4fee-d9a0533bf8215100a923f6552775048c2844a240
61 lines
2.2 KiB
Haskell
61 lines
2.2 KiB
Haskell
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)
|
|
)
|