3f8c3bbb26
Ignore-this: 3b03abece3edb25c656f84db9cef7734 darcs-hash:20121017171258-76d51-76a4e9057c0a4c3c1370485f3dc072c18caafddf
48 lines
1.6 KiB
Haskell
48 lines
1.6 KiB
Haskell
{-# LANGUAGE DeriveDataTypeable #-}
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{- | This module implements UTF-32 encoding and decoding.
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See <http://en.wikipedia.org/wiki/UTF-32> for more information.
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-}
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module Data.Encoding.UTF32
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(UTF32(..))
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where
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import Data.Encoding.Base
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import Data.Encoding.ByteSink
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import Data.Encoding.ByteSource
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import Data.Encoding.Exception
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import Data.Char
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import Data.Typeable
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data UTF32
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= UTF32 -- ^ Detects big or little endian through the use of the BOM (Byte Order Mask) character. Defaults to big endian if not present.
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| UTF32BE -- ^ Encodes and decodes using the big endian encoding.
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| UTF32LE -- ^ Encodes and decodes using the little endian encoding.
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deriving (Eq,Show,Typeable)
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instance Encoding UTF32 where
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encodeChar UTF32LE ch = pushWord32le (fromIntegral $ ord ch)
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encodeChar _ ch = pushWord32be (fromIntegral $ ord ch)
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decodeChar UTF32LE = do
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wrd <- fetchWord32le
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return $ chr $ fromIntegral wrd
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decodeChar _ = do
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wrd <- fetchWord32be
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return $ chr $ fromIntegral wrd
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encode UTF32 str = do
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encodeChar UTF32 '\xFEFF'
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mapM_ (encodeChar UTF32) str
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encode enc str = mapM_ (encodeChar enc) str
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decode UTF32 = do
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ch <- fetchWord32be
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case ch of
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0x0000FEFF -> untilM sourceEmpty (decodeChar UTF32BE)
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0xFFFE0000 -> untilM sourceEmpty (decodeChar UTF32LE)
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_ -> do
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rest <- untilM sourceEmpty (decodeChar UTF32)
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return ((chr $ fromIntegral ch):rest)
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decode enc = untilM sourceEmpty (decodeChar enc)
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encodeable _ _ = True
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