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20 lines
471 B
Haskell
20 lines
471 B
Haskell
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module SharedString (shareString) where
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import Data.HashTable as H
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import System.IO.Unsafe (unsafePerformIO)
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{-# NOINLINE stringPool #-}
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stringPool :: HashTable String String
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stringPool = unsafePerformIO $ new (==) hashString
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{-# NOINLINE shareString #-}
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shareString :: String -> String
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shareString s = unsafePerformIO $ do
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mv <- H.lookup stringPool s
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case mv of
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Just s' -> return s'
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Nothing -> do
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H.insert stringPool s s
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return s
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