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{-# LANGUAGE TypeFamilies, FlexibleInstances #-}
module Data.Interned.Internal.String
( InternedString(..)
) where
import Data.String
import Data.Interned
import Data.Hashable
import qualified Data.Foldable as F
data InternedString = IS
{ internedStringId :: {-# UNPACK #-} !Id
, uninternString :: String
}
instance IsString InternedString where
fromString = intern
instance Eq InternedString where
IS i _ == IS j _ = i == j
instance Ord InternedString where
compare (IS i _) (IS j _) = compare i j
instance Show InternedString where
showsPrec d (IS _ b) = showsPrec d b
instance Hashable InternedString where
hashWithSalt s (IS i _) = hashWithSalt s i
instance Interned InternedString where
type Uninterned InternedString = String
data Description InternedString = Cons {-# UNPACK #-} !Char String | Nil
deriving (Eq)
describe (c:cs) = Cons c cs
describe [] = Nil
identify = IS
cache = stringCache
instance Uninternable InternedString where
unintern = uninternString
instance Hashable (Description InternedString) where
hashWithSalt s (Cons c cs) = F.foldl' hashWithSalt (hashWithSalt s c) cs
hashWithSalt s Nil = s `hashWithSalt` (0 :: Int)
stringCache :: Cache InternedString
stringCache = mkCache
{-# NOINLINE stringCache #-}
|
