-{-# OPTIONS -fno-implicit-prelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude #-}
+
-----------------------------------------------------------------------------
-- |
-- Module : Foreign.ForeignPtr
module Foreign.ForeignPtr
(
- -- * Finalised data pointers
- ForeignPtr, -- abstract, instance of: Eq
- , newForeignPtr -- :: Ptr a -> IO () -> IO (ForeignPtr a)
- , addForeignPtrFinalizer -- :: ForeignPtr a -> IO () -> IO ()
- , withForeignPtr -- :: ForeignPtr a -> (Ptr a -> IO b) -> IO b
- , foreignPtrToPtr -- :: ForeignPtr a -> Ptr a
- , touchForeignPtr -- :: ForeignPtr a -> IO ()
- , castForeignPtr -- :: ForeignPtr a -> ForeignPtr b
+ -- * 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
+
+#ifdef __GLASGOW_HASKELL__
+ , finalizeForeignPtr
+#endif
+
+ -- ** Low-level operations
+ , unsafeForeignPtrToPtr
+ , touchForeignPtr
+ , castForeignPtr
+
+ -- ** Allocating managed memory
+ , mallocForeignPtr
+ , mallocForeignPtrBytes
+ , mallocForeignPtrArray
+ , mallocForeignPtrArray0
)
- where
+ where
import Foreign.Ptr
-import Data.Dynamic
+
+#ifdef __NHC__
+import NHC.FFI
+ ( ForeignPtr
+ , FinalizerPtr
+ , newForeignPtr
+ , newForeignPtr_
+ , addForeignPtrFinalizer
+ , withForeignPtr
+ , unsafeForeignPtrToPtr
+ , touchForeignPtr
+ , castForeignPtr
+ , Storable(sizeOf)
+ , malloc, mallocBytes, finalizerFree
+ )
+#endif
+
+#ifdef __HUGS__
+import Hugs.ForeignPtr
+#endif
+
+#ifndef __NHC__
+import Foreign.Storable ( Storable(sizeOf) )
+#endif
#ifdef __GLASGOW_HASKELL__
import GHC.Base
-import GHC.IOBase
+-- import GHC.IO
import GHC.Num
-import GHC.Err
+import GHC.Err ( undefined )
+import GHC.ForeignPtr
#endif
-#include "Dynamic.h"
-INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr")
+#if !defined(__NHC__) && !defined(__GLASGOW_HASKELL__)
+import Foreign.Marshal.Alloc ( malloc, mallocBytes, finalizerFree )
-#ifdef __GLASGOW_HASKELL__
--- |The type 'ForeignPtr' represents references to objects that are
--- maintained in a foreign language, i.e., that are not part of the
--- data structures usually managed by the Haskell storage manager.
--- The essential difference between 'ForeignPtr's and vanilla memory
--- references of type @Ptr a@ is that the former may be associated
--- with /finalisers/. A finaliser is a routine that is invoked when
--- the Haskell storage manager detects that - within the Haskell heap
--- and stack - there are no more references left that are pointing to
--- the 'ForeignPtr'. Typically, the finaliser will, then, invoke
--- routines in the foreign language that free the resources bound by
--- the foreign object.
---
--- The 'ForeignPtr' is parameterised in the same way as 'Ptr'. The
--- type argument of 'ForeignPtr' should normally be an instance of
--- class 'Storable'.
---
-data ForeignPtr a = ForeignPtr ForeignObj#
+instance Eq (ForeignPtr a) where
+ p == q = unsafeForeignPtrToPtr p == unsafeForeignPtrToPtr q
-instance CCallable (ForeignPtr a)
+instance Ord (ForeignPtr a) where
+ compare p q = compare (unsafeForeignPtrToPtr p) (unsafeForeignPtrToPtr q)
-eqForeignPtr :: ForeignPtr a -> ForeignPtr a -> Bool
-eqForeignPtr (ForeignPtr fo1#) (ForeignPtr fo2#) = eqForeignObj# fo1# fo2#
+instance Show (ForeignPtr a) where
+ showsPrec p f = showsPrec p (unsafeForeignPtrToPtr f)
+#endif
-instance Eq (ForeignPtr a) where
- p == q = eqForeignPtr p q
- p /= q = not (eqForeignPtr p q)
-
-newForeignPtr :: Ptr a -> IO () -> IO (ForeignPtr a)
--- ^Turns a plain memory reference into a foreign object
--- by associating a finaliser - given by the monadic operation
--- - 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 p finalizer
- = do fObj <- mkForeignPtr p
- addForeignPtrFinalizer fObj finalizer
- return fObj
-addForeignPtrFinalizer :: ForeignPtr a -> IO () -> IO ()
--- ^This function adds another finaliser to the given
--- foreign object. No guarantees are made on the order in
--- which multiple finalisers for a single object are run.
-addForeignPtrFinalizer (ForeignPtr fo) finalizer =
- IO $ \s -> case mkWeak# fo () finalizer s of { (# s1, w #) -> (# s1, () #) }
-
-mkForeignPtr :: Ptr a -> IO (ForeignPtr a) {- not exported -}
-mkForeignPtr (Ptr obj) = IO ( \ s# ->
- case mkForeignObj# obj s# of
- (# s1#, fo# #) -> (# s1#, ForeignPtr fo# #) )
-
-touchForeignPtr :: ForeignPtr a -> IO ()
--- ^This function ensures that the foreign object in
--- question is alive at the given place in the sequence of IO
--- actions. In particular 'withForeignPtr'
--- does a 'touchForeignPtr' after it
--- executes the user action.
---
--- This function can be used to express liveness
--- dependencies between 'ForeignPtr's: for
--- example, if the finalizer for one
--- 'ForeignPtr' touches a second
--- 'ForeignPtr', then it is ensured that the
--- second 'ForeignPtr' will stay alive at
--- least as long as the first. This can be useful when you
--- want to manipulate /interior pointers/ to
--- a foreign structure: you can use
--- 'touchForeignObj' to express the
--- requirement that the exterior pointer must not be finalized
--- until the interior pointer is no longer referenced.
-touchForeignPtr (ForeignPtr fo)
- = IO $ \s -> case touch# fo s of s -> (# s, () #)
+#ifndef __NHC__
+newForeignPtr :: FinalizerPtr a -> Ptr a -> IO (ForeignPtr a)
+-- ^Turns a plain memory reference into a foreign pointer, and
+-- associates a finalizer with the reference. The finalizer will be
+-- executed after the last reference to the foreign object is dropped.
+-- There is no guarantee of promptness, however the finalizer will be
+-- executed before the program exits.
+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
-- 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
--- 'foreignPtrToPtr' below: the finalizer
+-- 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.
-- 'ForeignPtr', using the operations from the
-- 'Storable' class.
withForeignPtr fo io
- = do r <- io (foreignPtrToPtr fo)
+ = do r <- io (unsafeForeignPtrToPtr fo)
touchForeignPtr fo
return r
-
-foreignPtrToPtr :: ForeignPtr a -> Ptr a
--- ^This function extracts the pointer component of a foreign
--- pointer. This is a potentially dangerous operations, as if the
--- argument to 'foreignPtrToPtr' is the last usage
--- occurence of the given foreign pointer, then its finaliser(s) will
--- be run, which potentially invalidates the plain pointer just
--- obtained. Hence, 'touchForeignPtr' must be used
--- wherever it has to be guaranteed that the pointer lives on - i.e.,
--- has another usage occurrence.
---
--- To avoid subtle coding errors, hand written marshalling code
--- should preferably use 'withForeignPtr' rather
--- than combinations of 'foreignPtrToPtr' and
--- 'touchForeignPtr'. However, the later routines
--- are occasionally preferred in tool generated marshalling code.
-foreignPtrToPtr (ForeignPtr fo) = Ptr (foreignObjToAddr# fo)
-
-castForeignPtr :: ForeignPtr a -> ForeignPtr b
--- ^This function casts a 'ForeignPtr'
--- parameterised by one type into another type.
-castForeignPtr (ForeignPtr a) = ForeignPtr a
-#endif
-
+#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__ */
+
+#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 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)
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