encoding/Data/Encoding/KOI8U.hs
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2012-10-17 10:12:58 -07:00

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Haskell

{-# LANGUAGE DeriveDataTypeable #-}
{- | This module implements KOI8-U encoding which covers the ukrainian alphabet.
See <http://en.wikipedia.org/wiki/KOI8-U> for more information.
-}
module Data.Encoding.KOI8U
(KOI8U(..)) where
import Data.Encoding.Base
import Data.Encoding.ByteSource
import Data.Encoding.ByteSink
import Data.Encoding.Exception
import Control.Throws
import Data.Word
import Data.Array.Unboxed
import Data.Char (chr,ord)
import Data.Map (Map,fromList,lookup,member)
import Prelude hiding (lookup)
import Data.Typeable
data KOI8U = KOI8U deriving (Eq,Show,Typeable)
koi8uArr :: UArray Word8 Char
koi8uArr = listArray (128,255) koi8uList
koi8uMap :: Map Char Word8
koi8uMap = fromList (zip koi8uList [128..])
koi8uList :: [Char]
koi8uList =
['\x2500','\x2502','\x250c','\x2510','\x2514','\x2518','\x251c','\x2524'
,'\x252c','\x2534','\x253c','\x2580','\x2584','\x2588','\x258c','\x2590'
,'\x2591','\x2592','\x2593','\x2320','\x25a0','\x2219','\x221a','\x2248'
,'\x2264','\x2265','\x00a0','\x2321','\x00b0','\x00b2','\x00b7','\x00f7'
,'\x2550','\x2551','\x2552','\x0451','\x0454','\x2554','\x0456','\x0457'
,'\x2557','\x2558','\x2559','\x255a','\x255b','\x0491','\x255d','\x255e'
,'\x255f','\x2560','\x2561','\x0401','\x0403','\x2563','\x0406','\x0407'
,'\x2566','\x2567','\x2568','\x2569','\x256a','\x0490','\x256c','\x00a9'
,'\x044e','\x0430','\x0431','\x0446','\x0434','\x0435','\x0444','\x0433'
,'\x0445','\x0438','\x0439','\x043a','\x043b','\x043c','\x043d','\x043e'
,'\x043f','\x044f','\x0440','\x0441','\x0442','\x0443','\x0436','\x0432'
,'\x044c','\x044b','\x0437','\x0448','\x044d','\x0449','\x0447','\x044a'
,'\x042e','\x0410','\x0411','\x0426','\x0414','\x0415','\x0424','\x0413'
,'\x0425','\x0418','\x0419','\x041a','\x041b','\x041c','\x041d','\x041e'
,'\x041f','\x042f','\x0420','\x0421','\x0422','\x0423','\x0416','\x0412'
,'\x042c','\x042b','\x0417','\x0428','\x042d','\x0429','\x0427','\x042a'
]
instance Encoding KOI8U where
decodeChar _ = do
w <- fetchWord8
if w < 128
then return $ chr $ fromIntegral w
else return $ koi8uArr!w
encodeChar _ ch
| ch < '\128' = pushWord8 $ fromIntegral $ ord ch
| otherwise = case lookup ch koi8uMap of
Just w -> pushWord8 w
Nothing -> throwException (HasNoRepresentation ch)
encodeable _ c = member c koi8uMap