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|
{-# LANGUAGE CPP #-}
{-# OPTIONS_HADDOCK hide #-}
-- GIMP Toolkit (GTK) FFI extras and version dependencies
--
-- Author : Axel Simon
--
-- Created: 22 June 2001
--
-- Copyright (C) 1999-2005 Axel Simon
--
-- This library is free software; you can redistribute it and/or
-- modify it under the terms of the GNU Lesser General Public
-- License as published by the Free Software Foundation; either
-- version 2.1 of the License, or (at your option) any later version.
--
-- This library is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-- Lesser General Public License for more details.
--
-- #hide
-- |
--
-- This module serves as an impedance matcher for different compiler
-- versions. It also adds a few FFI utility functions.
--
module System.Glib.FFI (
nullForeignPtr,
maybeNull,
newForeignPtr,
withForeignPtrs,
#if MIN_VERSION_base(4,4,0)
unsafePerformIO,
unsafeForeignPtrToPtr,
#endif
module Foreign,
module Foreign.C
) where
-- We should almost certainly not be using the standard free function anywhere
-- in the glib or gtk bindings, so we do not re-export it from this module.
import Foreign.C
#if MIN_VERSION_base(4,4,0)
import Foreign hiding (unsafePerformIO, unsafeForeignPtrToPtr, newForeignPtr, free)
import System.IO.Unsafe (unsafePerformIO)
import Foreign.ForeignPtr.Unsafe (unsafeForeignPtrToPtr)
#else
import Foreign hiding (newForeignPtr, free)
#endif
import qualified Foreign.Concurrent
newForeignPtr :: Ptr a -> FinalizerPtr a -> IO (ForeignPtr a)
newForeignPtr p finalizer
= Foreign.Concurrent.newForeignPtr p (mkFinalizer finalizer p)
foreign import ccall "dynamic"
mkFinalizer :: FinalizerPtr a -> Ptr a -> IO ()
nullForeignPtr :: ForeignPtr a
nullForeignPtr = unsafePerformIO $ newForeignPtr_ nullPtr
-- This is useful when it comes to marshaling lists of GObjects
--
withForeignPtrs :: [ForeignPtr a] -> ([Ptr a] -> IO b) -> IO b
withForeignPtrs fptrs body = do
result <- body (map unsafeForeignPtrToPtr fptrs)
mapM_ touchForeignPtr fptrs
return result
-- A marshaling utility function that is used by the code produced by the code
-- generator to marshal return values that can be null
maybeNull :: (IO (Ptr a) -> IO a) -> IO (Ptr a) -> IO (Maybe a)
maybeNull marshal genPtr = do
ptr <- genPtr
if ptr == nullPtr
then return Nothing
else do result <- marshal (return ptr)
return (Just result)
|
