1 % ------------------------------------------------------------------------------
2 % $Id: Weak.lhs,v 1.2 2001/07/03 14:13:32 simonmar Exp $
4 % (c) The University of Glasgow, 1998-2000
7 \section[GHC.Weak]{Module @GHC.Weak@}
10 {-# OPTIONS -fno-implicit-prelude #-}
17 import GHC.IOBase ( IO(..), unIO )
19 data Weak v = Weak (Weak# v)
23 -> Maybe (IO ()) -- finalizer
24 -> IO (Weak v) -- weak pointer
26 mkWeak key val (Just finalizer) = IO $ \s ->
27 case mkWeak# key val finalizer s of { (# s1, w #) -> (# s1, Weak w #) }
28 mkWeak key val Nothing = IO $ \s ->
29 case mkWeak# key val (unsafeCoerce# 0#) s of { (# s1, w #) -> (# s1, Weak w #) }
31 mkWeakPtr :: k -> Maybe (IO ()) -> IO (Weak k)
32 mkWeakPtr key finalizer = mkWeak key key finalizer
34 addFinalizer :: key -> IO () -> IO ()
35 addFinalizer key finalizer = do
36 mkWeakPtr key (Just finalizer) -- throw it away
40 Instance Eq (Weak v) where
41 (Weak w1) == (Weak w2) = w1 `sameWeak#` w2
45 -- run a batch of finalizers from the garbage collector. We're given
46 -- an array of finalizers and the length of the array, and we just
47 -- call each one in turn.
49 -- the IO primitives are inlined by hand here to get the optimal
52 runFinalizerBatch :: Int -> Array# (IO ()) -> IO ()
53 runFinalizerBatch (I# n) arr =
57 _ -> let m' = m -# 1# in
58 case indexArray# arr m' of { (# io #) ->
59 case unIO io s of { (# s, _ #) ->