content: {-# LANGUAGE Unsafe #-}
  {-# LANGUAGE NoImplicitPrelude #-}
  {-# OPTIONS_HADDOCK not-home #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  GHC.Internal.Foreign.ForeignPtr.Imp
  -- Copyright   :  (c) The University of Glasgow 2001
  -- License     :  BSD-style (see the file libraries/base/LICENSE)
  --
  -- Maintainer  :  ffi@haskell.org
  -- Stability   :  provisional
  -- Portability :  portable
  --
  -- The 'ForeignPtr' type and operations.  This module is part of the
  -- Foreign Function Interface (FFI) and will usually be imported via
  -- the "Foreign" module.
  --
  -----------------------------------------------------------------------------
  
  module GHC.Internal.Foreign.ForeignPtr.Imp
          (
          -- * Finalised data pointers
            ForeignPtr
          , FinalizerPtr
          , FinalizerEnvPtr
  
          -- ** Basic operations
          , newForeignPtr
          , newForeignPtr_
          , addForeignPtrFinalizer
          , newForeignPtrEnv
          , addForeignPtrFinalizerEnv
          , withForeignPtr
          , finalizeForeignPtr
  
          -- ** Low-level operations
          , unsafeForeignPtrToPtr
          , touchForeignPtr
          , castForeignPtr
          , plusForeignPtr
  
          -- ** Allocating managed memory
          , mallocForeignPtr
          , mallocForeignPtrBytes
          , mallocForeignPtrArray
          , mallocForeignPtrArray0
          )
          where
  
  import GHC.Internal.Foreign.Ptr
  import GHC.Internal.Foreign.Storable ( Storable(sizeOf) )
  
  import GHC.Internal.Base
  import GHC.Internal.Num
  import GHC.Internal.ForeignPtr
  
  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
  
  -- | 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
  
  -- | This function is similar to 'GHC.Internal.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 'GHC.Internal.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 'GHC.Internal.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 'GHC.Internal.Foreign.Marshal.Alloc.malloc'.
  mallocForeignPtrArray0      :: Storable a => Int -> IO (ForeignPtr a)
  mallocForeignPtrArray0 size  = mallocForeignPtrArray (size + 1)
  
  