-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
-----------------------------------------------------------------------------
-- |
-- Module : Foreign.ForeignPtr
-- * Finalised data pointers
ForeignPtr
, FinalizerPtr
+#ifdef __HUGS__
+ , FinalizerEnvPtr
+#endif
+ -- ** Basic operations
, newForeignPtr
, newForeignPtr_
, addForeignPtrFinalizer
+#ifdef __HUGS__
+ , newForeignPtrEnv
+ , addForeignPtrFinalizerEnv
+#endif
, withForeignPtr
+
+#ifdef __GLASGOW_HASKELL__
+ , finalizeForeignPtr
+#endif
+
+ -- ** Low-level operations
, unsafeForeignPtrToPtr
, touchForeignPtr
, castForeignPtr
+ -- ** Allocating managed memory
, mallocForeignPtr
, mallocForeignPtrBytes
, mallocForeignPtrArray
#if !defined(__NHC__) && !defined(__GLASGOW_HASKELL__)
import Foreign.Marshal.Alloc ( malloc, mallocBytes, finalizerFree )
-import Data.Dynamic
+import Data.Typeable
-#include "Dynamic.h"
+#include "Typeable.h"
INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr")
instance Eq (ForeignPtr a) where
#ifndef __NHC__
+newForeignPtr :: FinalizerPtr a -> Ptr a -> IO (ForeignPtr a)
+-- ^Turns a plain memory reference into a foreign pointer, and
+-- associates a finaliser with the reference. The finaliser will be executed
+-- after the last reference to the foreign object is dropped. Note that there
+-- is no guarantee on how soon the finaliser is executed after the last
+-- reference was dropped; this depends on the details of the Haskell storage
+-- manager. The only guarantee is that the finaliser runs before the program
+-- terminates.
+newForeignPtr finalizer p
+ = do fObj <- newForeignPtr_ p
+ addForeignPtrFinalizer finalizer fObj
+ return fObj
+
withForeignPtr :: ForeignPtr a -> (Ptr a -> IO b) -> IO b
-- ^This is a way to look at the pointer living inside a
-- foreign object. This function takes a function which is
-- the action and use it after the action completes. All uses
-- of the pointer should be inside the
-- 'withForeignPtr' bracket. The reason for
--- this unsafety is the same as for
+-- this unsafeness is the same as for
-- 'unsafeForeignPtrToPtr' below: the finalizer
-- may run earlier than expected, because the compiler can only
-- track usage of the 'ForeignPtr' object, not
#endif /* ! __NHC__ */
#ifdef __HUGS__
--- temporary aliasing until hugs catches up
-unsafeForeignPtrToPtr = foreignPtrToPtr
-#endif
+-- | This variant of 'newForeignPtr' adds a finalizer that expects an
+-- environment in addition to the finalized pointer. The environment
+-- that will be passed to the finalizer is fixed by the second argument to
+-- 'newForeignPtrEnv'.
+newForeignPtrEnv ::
+ FinalizerEnvPtr env a -> Ptr env -> Ptr a -> IO (ForeignPtr a)
+newForeignPtrEnv finalizer env p
+ = do fObj <- newForeignPtr_ p
+ addForeignPtrFinalizerEnv finalizer env fObj
+ return fObj
+#endif /* __HUGS__ */
#ifndef __GLASGOW_HASKELL__
mallocForeignPtr :: Storable a => IO (ForeignPtr a)
mallocForeignPtr = do
r <- malloc
- newForeignPtr r finalizerFree
+ newForeignPtr finalizerFree r
mallocForeignPtrBytes :: Int -> IO (ForeignPtr a)
mallocForeignPtrBytes n = do
r <- mallocBytes n
- newForeignPtr r finalizerFree
-#endif /* __HUGS__ || __NHC__ */
+ newForeignPtr finalizerFree r
+#endif /* !__GLASGOW_HASKELL__ */
+-- | This function is similar to 'Foreign.Marshal.Array.mallocArray',
+-- but yields a memory area that has a finalizer attached that releases
+-- the memory area. As with 'mallocForeignPtr', it is not guaranteed that
+-- the block of memory was allocated by 'Foreign.Marshal.Alloc.malloc'.
mallocForeignPtrArray :: Storable a => Int -> IO (ForeignPtr a)
mallocForeignPtrArray = doMalloc undefined
where
- doMalloc :: Storable a => a -> Int -> IO (ForeignPtr a)
+ doMalloc :: Storable b => b -> Int -> IO (ForeignPtr b)
doMalloc dummy size = mallocForeignPtrBytes (size * sizeOf dummy)
+-- | This function is similar to 'Foreign.Marshal.Array.mallocArray0',
+-- but yields a memory area that has a finalizer attached that releases
+-- the memory area. As with 'mallocForeignPtr', it is not guaranteed that
+-- the block of memory was allocated by 'Foreign.Marshal.Alloc.malloc'.
mallocForeignPtrArray0 :: Storable a => Int -> IO (ForeignPtr a)
mallocForeignPtrArray0 size = mallocForeignPtrArray (size + 1)