33 lines
1.0 KiB
Haskell
33 lines
1.0 KiB
Haskell
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
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{-# LANGUAGE TemplateHaskell #-}
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module Yesod.Internal.Cache
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( Cache
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, CacheKey
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, mkCacheKey
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, lookup
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, insert
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, delete
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) where
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import Prelude hiding (lookup)
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import qualified Data.IntMap as Map
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import Language.Haskell.TH.Syntax (Q, Exp, runIO, Exp (LitE), Lit (IntegerL))
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import Language.Haskell.TH (appE)
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import Data.Unique (hashUnique, newUnique)
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import Unsafe.Coerce (unsafeCoerce)
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import Control.Applicative ((<$>))
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import Yesod.Core.Types
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-- | Generate a new 'CacheKey'. Be sure to give a full type signature.
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mkCacheKey :: Q Exp
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mkCacheKey = [|CacheKey|] `appE` (LitE . IntegerL . fromIntegral . hashUnique <$> runIO newUnique)
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lookup :: CacheKey a -> Cache -> Maybe a
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lookup (CacheKey i) (Cache m) = unsafeCoerce <$> Map.lookup i m
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insert :: CacheKey a -> a -> Cache -> Cache
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insert (CacheKey k) v (Cache m) = Cache (Map.insert k (unsafeCoerce v) m)
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delete :: CacheKey a -> Cache -> Cache
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delete (CacheKey k) (Cache m) = Cache (Map.delete k m)
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