{-# LANGUAGE UnicodeSyntax , NoImplicitPrelude , KindSignatures #-} ------------------------------------------------------------------------------- -- | -- Module : Foreign.Ptr.Region.Internal -- Copyright : (c) 2010 Bas van Dijk -- License : BSD3 (see the file LICENSE) -- Maintainer : Bas van Dijk <v.dijk.bas@gmail.com> -- ------------------------------------------------------------------------------- module Foreign.Ptr.Region.Internal ( -- * Regional pointers RegionalPtr(RegionalPtr) -- * Unsafely constructing regional pointers , unsafeRegionalPtr , unsafePureRegionalPtr -- * Unsafe utility functions for lifting operations on @Ptrs@ to @RegionalPtrs@ , unsafePtr , unsafeWrap, unsafeWrap2, unsafeWrap3 ) where -------------------------------------------------------------------------------- -- Imports -------------------------------------------------------------------------------- -- from base: import Control.Monad ( return, (>>=), fail ) import Data.Function ( ($) ) import Data.Maybe ( Maybe(Nothing, Just) ) import System.IO ( IO ) import Foreign.Ptr ( Ptr ) -- from transformers: import Control.Monad.IO.Class ( MonadIO, liftIO ) -- from regions: import Control.Monad.Trans.Region.OnExit ( CloseHandle, CloseAction, onExit ) import Control.Monad.Trans.Region ( RegionT, Dup(dup) ) -------------------------------------------------------------------------------- -- * Regional pointers -------------------------------------------------------------------------------- -- | A regional handle to memory. This should provide a safer replacement for -- @Foreign.Ptr.'Ptr'@ data RegionalPtr α (r ∷ * → *) = RegionalPtr !(Ptr α) !(Maybe (CloseHandle r)) instance Dup (RegionalPtr α) where dup (RegionalPtr ptr Nothing) = return $ RegionalPtr ptr Nothing dup (RegionalPtr ptr (Just ch)) = do ch' ← dup ch return $ RegionalPtr ptr $ Just ch' -------------------------------------------------------------------------------- -- * Constructing regional pointers -------------------------------------------------------------------------------- -- | Construct a regional pointer from a native pointer -- and an @IO@ computation that finalizes the pointer (like @free ptr@) -- which is executed when the region exits. -- -- This function is considered unsafe because this library can't guarantee that -- the finalizer will actually finalize the pointer (suppose having @return ()@ -- as the finalizer). You have to verify the correct finalisation yourself. unsafeRegionalPtr ∷ MonadIO pr ⇒ Ptr α → CloseAction → RegionT s pr (RegionalPtr α (RegionT s pr)) unsafeRegionalPtr ptr finalize = do ch ← onExit finalize return $ RegionalPtr ptr $ Just ch -- | Construct a regional pointer from a native pointer -- without registering a finalizer like @free ptr@. -- -- This function is considered unsafe because this library can't guarantee the -- finalisation of the pointer, you have to do that yourself. unsafePureRegionalPtr ∷ Ptr α → RegionalPtr α r unsafePureRegionalPtr ptr = RegionalPtr ptr Nothing -------------------------------------------------------------------------------- -- * Utility functions for lifting operations on Ptrs to RegionalPtrs -------------------------------------------------------------------------------- unsafePtr ∷ RegionalPtr α r → Ptr α unsafePtr (RegionalPtr ptr _) = ptr unsafeWrap ∷ MonadIO m ⇒ (Ptr α → IO β) → (RegionalPtr α r → m β) unsafeWrap f rPtr = liftIO $ f (unsafePtr rPtr) unsafeWrap2 ∷ MonadIO m ⇒ (Ptr α → γ → IO β) → (RegionalPtr α r → γ → m β) unsafeWrap2 f rPtr x = liftIO $ f (unsafePtr rPtr) x unsafeWrap3 ∷ MonadIO m ⇒ (Ptr α → γ → δ → IO β) → (RegionalPtr α r → γ → δ → m β) unsafeWrap3 f rPtr x y = liftIO $ f (unsafePtr rPtr) x y -- The End ---------------------------------------------------------------------