8b1f45a6ec
Ignore-this: 6af2adadedc20f51bb5084b3da59724e darcs-hash:20121213030806-76d51-6d52680cab9b4f4b6c2ba17e29fa457b85d4d838
52 lines
1.9 KiB
Haskell
52 lines
1.9 KiB
Haskell
{-# LANGUAGE DeriveDataTypeable #-}
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{- | Implements the japanese character encoding ISO 2022-JP.
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See http://tools.ietf.org/html/rfc1468 for reference.
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-}
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module Data.Encoding.ISO2022JP where
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import Data.Typeable
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import Data.Encoding.Base
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import Data.Encoding.Exception
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import Data.Encoding.ByteSource
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import Data.Encoding.ISO2022
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import Data.Encoding.ASCII
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import Data.Encoding.JISX0201
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import Data.Encoding.JISX0208
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import Control.Throws
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data ISO2022JP = ISO2022JP deriving (Eq,Show,Typeable)
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instance Encoding ISO2022JP where
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encodeChar = encodeCharISO2022
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decodeChar = decodeCharISO2022
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encode = encodeISO2022
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decode = decodeISO2022
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encodeable _ c = encodeable ASCII c || encodeable JISX0201 c || encodeable JISX0208 c
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instance ISO2022 ISO2022JP where
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readEscape _ = fetchAhead $ do
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w <- fetchWord8
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if w == 27
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then (do
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w2 <- fetchWord8
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w3 <- fetchWord8
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case w2 of
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40 -> case w3 of
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66 -> return $ Just $ DynEncoding ASCII
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74 -> return $ Just $ DynEncoding JISX0201
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_ -> throwException (IllegalCharacter w3)
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36 -> case w3 of
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64 -> return $ Just $ DynEncoding JISX0208 -- XXX: this actually has to be the 1978 version of the standard... too bad I can't find it
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66 -> return $ Just $ DynEncoding JISX0208
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_ -> throwException (IllegalCharacter w3)
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_ -> throwException (IllegalCharacter w2)
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)
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else return Nothing
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encodingForChar _ c
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| encodeable ASCII c = Just (DynEncoding ASCII,[27,40,66])
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| encodeable JISX0201 c = Just (DynEncoding JISX0201,[27,40,74])
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| encodeable JISX0208 c = Just (DynEncoding JISX0208,[27,36,66])
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| otherwise = Nothing
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