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UnsafeTricks.hs
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UnsafeTricks.hs
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{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE CPP #-}
#ifdef UNSAFETRICKS
{-# LANGUAGE MagicHash #-}
#endif
module Data.HashTable.Internal.UnsafeTricks
( Key
, toKey
, fromKey
, emptyRecord
, deletedRecord
, keyIsEmpty
, keyIsDeleted
, writeDeletedElement
, makeEmptyVector
) where
import Control.Monad.Primitive
import Data.Vector.Mutable (MVector)
import qualified Data.Vector.Mutable as M
#ifdef UNSAFETRICKS
import GHC.Exts
import Unsafe.Coerce
#endif
------------------------------------------------------------------------------
#ifdef UNSAFETRICKS
type Key a = Any
#else
data Key a = Key !a
| EmptyElement
| DeletedElement
deriving (Show)
#endif
------------------------------------------------------------------------------
-- Type signatures
emptyRecord :: Key a
deletedRecord :: Key a
keyIsEmpty :: Key a -> Bool
keyIsDeleted :: Key a -> Bool
makeEmptyVector :: PrimMonad m => Int -> m (MVector (PrimState m) (Key a))
writeDeletedElement :: PrimMonad m =>
MVector (PrimState m) (Key a) -> Int -> m ()
toKey :: a -> Key a
fromKey :: Key a -> a
#ifdef UNSAFETRICKS
data TombStone = EmptyElement
| DeletedElement
{-# NOINLINE emptyRecord #-}
emptyRecord = unsafeCoerce EmptyElement
{-# NOINLINE deletedRecord #-}
deletedRecord = unsafeCoerce DeletedElement
{-# INLINE keyIsEmpty #-}
keyIsEmpty a = isTrue# (x# ==# 1#)
where
!x# = reallyUnsafePtrEquality# a emptyRecord
{-# INLINE keyIsDeleted #-}
keyIsDeleted a = isTrue# (x# ==# 1#)
where
!x# = reallyUnsafePtrEquality# a deletedRecord
{-# INLINE toKey #-}
toKey = unsafeCoerce
{-# INLINE fromKey #-}
fromKey = unsafeCoerce
#else
emptyRecord = EmptyElement
deletedRecord = DeletedElement
keyIsEmpty EmptyElement = True
keyIsEmpty _ = False
keyIsDeleted DeletedElement = True
keyIsDeleted _ = False
toKey = Key
fromKey (Key x) = x
fromKey _ = error "impossible"
#endif
------------------------------------------------------------------------------
{-# INLINE makeEmptyVector #-}
makeEmptyVector m = M.replicate m emptyRecord
------------------------------------------------------------------------------
{-# INLINE writeDeletedElement #-}
writeDeletedElement v i = M.unsafeWrite v i deletedRecord