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Patch 1 #12

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Patch 1 #12

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9e185a2
Update CP437.hs
michaelt Mar 5, 2016
09d8370
unfoldrN + remove unneeded Data.Monoid
michaelt Mar 5, 2016
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15 changes: 8 additions & 7 deletions Codec/Archive/Zip/CP437.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,19 +15,20 @@ where

import Data.ByteString (ByteString)
import Data.Char
import Data.Monoid
import Data.Text (Text)
import Data.Text.Lazy (toStrict)
import Data.Word (Word8)
import qualified Data.ByteString as B
import qualified Data.Text.Lazy.Builder as LB
import qualified Data.Text as T

-- | Decode a 'ByteString' containing CP 437 encoded text.

decodeCP437 :: ByteString -> Text
decodeCP437 = toStrict . LB.toLazyText . B.foldl' f mempty
where f xs b = xs <> LB.singleton (decodeByteCP437 b)

decodeCP437 bs = T.unfoldrN
(B.length bs)
(fmap (\(b,rest) -> (decodeByteCP437 b, rest)) . B.uncons)
bs


-- | Decode single byte of CP437 encoded text.

decodeByteCP437 :: Word8 -> Char
Expand Down Expand Up @@ -160,4 +161,4 @@ decodeByteCP437 byte = chr $ case byte of
253 -> 178
254 -> 9632
255 -> 160
x -> fromIntegral x -- the rest of characters translate directly
x -> fromIntegral x -- the rest of characters translate directly