[project @ 1999-02-02 14:19:02 by simonm]

[ghc-hetmet.git] / ghc / lib / exts / Weak.lhs

diff --git a/ghc/lib/exts/Weak.lhs b/ghc/lib/exts/Weak.lhs
index be0c025..dbbe34a 100644 (file)
--- a/ghc/lib/exts/Weak.lhs
+++ b/ghc/lib/exts/Weak.lhs
@@ -2,18 +2,16 @@
 % (c) The AQUA Project, Glasgow University, 1998
 %
 
-\section[Weak]{Module @PrelWeak@}
+\section[Weak]{Module @Weak@}
 
 \begin{code}
-{-# OPTIONS -fno-implicit-prelude #-}
-
 module Weak (
        Weak,                   -- abstract
        -- instance Eq (Weak v)  
 
        mkWeak,                 -- :: k -> v -> IO () -> IO (Weak v)
        deRefWeak,              -- :: Weak v -> IO (Maybe v)
-       -- finalise             -- :: Weak v -> IO ()
+       finalise,               -- :: Weak v -> IO ()
        -- replaceFinaliser     -- :: Weak v -> IO () -> IO ()
        mkWeakNoFinaliser,      -- :: k -> v -> IO (Weak v)
 
@@ -23,6 +21,28 @@ module Weak (
        addForeignFinaliser     -- :: ForeignObj -> IO () -> IO ()
    ) where
 
+import PrelBase
+import PrelIOBase
 import PrelWeak
 import Foreign
+
+deRefWeak :: Weak v -> IO (Maybe v)
+deRefWeak (Weak w) = IO $ \s ->
+   case deRefWeak# w s of
+       (# s1, flag, p #) -> case flag of
+                               0# -> (# s1, Nothing #)
+                               _  -> (# s1, Just p #)
+
+mkWeakNoFinaliser key val = IO $ \s ->
+   -- zero is a valid finaliser argument to mkWeak#, and means "no finaliser"
+   case mkWeak# key val (unsafeCoerce# 0#) s of { (# s1, w #) ->
+   (# s1, Weak w #) }
+
+mkWeakPair :: k -> v -> IO () -> IO (Weak (k,v))
+mkWeakPair key val finaliser = mkWeak key (key,val) finaliser
+
+finalise :: Weak v -> IO ()
+finalise (Weak w) = IO $ \s ->
+   case finaliseWeak# w s of s1 -> (# s1, () #)
+
 \end{code}