-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
-----------------------------------------------------------------------------
-- |
-- Module : Foreign.ForeignPtr
(
-- * Finalised data pointers
ForeignPtr
+ , FinalizerPtr
+#if defined(__HUGS__) || defined(__GLASGOW_HASKELL__)
+ , FinalizerEnvPtr
+#endif
+ -- ** Basic operations
, newForeignPtr
+ , newForeignPtr_
, addForeignPtrFinalizer
+#if defined(__HUGS__) || defined(__GLASGOW_HASKELL__)
+ , newForeignPtrEnv
+ , addForeignPtrFinalizerEnv
+#endif
, withForeignPtr
- , foreignPtrToPtr
+
+#ifdef __GLASGOW_HASKELL__
+ , finalizeForeignPtr
+#endif
+
+ -- ** Low-level operations
+ , unsafeForeignPtrToPtr
, touchForeignPtr
, castForeignPtr
-#ifndef __NHC__
+ -- ** Allocating managed memory
, mallocForeignPtr
, mallocForeignPtrBytes
, mallocForeignPtrArray
, mallocForeignPtrArray0
-#endif
)
where
+import Foreign.Ptr
+
#ifdef __NHC__
import NHC.FFI
( ForeignPtr
+ , FinalizerPtr
, newForeignPtr
+ , newForeignPtr_
, addForeignPtrFinalizer
, withForeignPtr
- , foreignPtrToPtr
+ , unsafeForeignPtrToPtr
, touchForeignPtr
, castForeignPtr
+ , Storable(sizeOf)
+ , malloc, mallocBytes, finalizerFree
)
#endif
-#ifdef __GLASGOW_HASKELL__
-import GHC.ForeignPtr
-#endif
-
#ifdef __HUGS__
import Hugs.ForeignPtr
#endif
import GHC.IOBase
import GHC.Num
import GHC.Err ( undefined )
+import GHC.ForeignPtr
#endif
+#if !defined(__NHC__) && !defined(__GLASGOW_HASKELL__)
+import Foreign.Marshal.Alloc ( malloc, mallocBytes, finalizerFree )
+
+instance Eq (ForeignPtr a) where
+ p == q = unsafeForeignPtrToPtr p == unsafeForeignPtrToPtr q
+
+instance Ord (ForeignPtr a) where
+ compare p q = compare (unsafeForeignPtrToPtr p) (unsafeForeignPtrToPtr q)
+
+instance Show (ForeignPtr a) where
+ showsPrec p f = showsPrec p (unsafeForeignPtrToPtr f)
+#endif
+
+
#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
+-- applied to that pointer. The resulting 'IO' action is then
+-- executed. The foreign object is kept alive at least during
+-- the whole action, even if it is not used directly
+-- inside. Note that it is not safe to return the pointer from
+-- the action and use it after the action completes. All uses
+-- of the pointer should be inside the
+-- 'withForeignPtr' bracket. The reason 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
+-- a 'Ptr' object made from it.
+--
+-- This function is normally used for marshalling data to
+-- or from the object pointed to by the
+-- 'ForeignPtr', using the operations from the
+-- 'Storable' class.
+withForeignPtr fo io
+ = do r <- io (unsafeForeignPtrToPtr fo)
+ touchForeignPtr fo
+ return r
+#endif /* ! __NHC__ */
+
+#if defined(__HUGS__) || defined(__GLASGOW_HASKELL__)
+-- | 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__ */
+
+#ifdef __GLASGOW_HASKELL__
+type FinalizerEnvPtr env a = FunPtr (Ptr env -> Ptr a -> IO ())
+
+-- | like 'addForeignPtrFinalizerEnv' but allows the finalizer to be
+-- passed an additional environment parameter to be passed to the
+-- finalizer. The environment passed to the finalizer is fixed by the
+-- second argument to 'addForeignPtrFinalizerEnv'
+addForeignPtrFinalizerEnv ::
+ FinalizerEnvPtr env a -> Ptr env -> ForeignPtr a -> IO ()
+addForeignPtrFinalizerEnv finalizer env fptr =
+ addForeignPtrConcFinalizer fptr
+ (mkFinalizerEnv finalizer env (unsafeForeignPtrToPtr fptr))
+
+foreign import ccall "dynamic"
+ mkFinalizerEnv :: FinalizerEnvPtr env a -> Ptr env -> Ptr a -> IO ()
+#endif
+
+
+#ifndef __GLASGOW_HASKELL__
+mallocForeignPtr :: Storable a => IO (ForeignPtr a)
+mallocForeignPtr = do
+ r <- malloc
+ newForeignPtr finalizerFree r
+
+mallocForeignPtrBytes :: Int -> IO (ForeignPtr a)
+mallocForeignPtrBytes n = do
+ r <- mallocBytes n
+ 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)
-#endif
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