35 lines
968 B
Haskell
35 lines
968 B
Haskell
module Encoding.Rotate
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( rotate ) where
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import Data.Maybe (fromMaybe)
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import Data.ByteString as B
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import qualified Data.ByteString.Char8 as BC
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upperCase = BC.pack ['A' .. 'Z']
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lowerCase = BC.pack ['a' .. 'z']
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-- rotate :: Int -> String -> String
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-- rotate n s = map (rotchar n) s
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-- where
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-- rotchar n c =
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-- case (lookup c $ transp n lowerCase) of
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-- Just x -> x
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-- Nothing -> fromMaybe c (lookup c $ transp n upperCase)
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rotate :: Int -> BC.ByteString -> BC.ByteString
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rotate n s = BC.map (rotchar n) s
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where
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rotchar :: Int -> Char -> Char
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rotchar n c =
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case (lookup c $ transp n lowerCase) of
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Just x -> x
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Nothing -> fromMaybe c (lookup c $ transp n upperCase)
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-- transp :: Int -> [Char] -> [(Char, Char)]
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-- transp n x = zip x ((drop n x) ++ (take n x))
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transp :: Int -> BC.ByteString -> [(Char, Char)]
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transp n x = Prelude.zip (BC.unpack x) (BC.unpack $ BC.append (BC.drop n x) (BC.take n x))
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