Once.hs


{- |
Copyright  : Will Thompson, Iñaki García Etxebarria and Jonas Platte
License    : LGPL-2.1
Maintainer : Iñaki García Etxebarria (garetxe@gmail.com)

A #GOnce struct controls a one-time initialization function. Any
one-time initialization function must have its own unique #GOnce
struct.
-}

module GI.GLib.Structs.Once
    ( 

-- * Exported types
    Once(..)                                ,
    newZeroOnce                             ,
    noOnce                                  ,


 -- * Methods
-- ** onceInitEnter
    onceInitEnter                           ,


-- ** onceInitLeave
    onceInitLeave                           ,




 -- * Properties
-- ** Retval
    onceReadRetval                          ,


-- ** Status
    onceReadStatus                          ,




    ) where

import Prelude ()
import Data.GI.Base.ShortPrelude

import qualified Data.Text as T
import qualified Data.ByteString.Char8 as B
import qualified Data.Map as Map

import GI.GLib.Types
import GI.GLib.Callbacks

newtype Once = Once (ForeignPtr Once)
-- | Construct a `Once` struct initialized to zero.
newZeroOnce :: MonadIO m => m Once
newZeroOnce = liftIO $ callocBytes 16 >>= wrapPtr Once

noOnce :: Maybe Once
noOnce = Nothing

onceReadStatus :: Once -> IO OnceStatus
onceReadStatus s = withManagedPtr s $ \ptr -> do
    val <- peek (ptr `plusPtr` 0) :: IO CUInt
    let val' = (toEnum . fromIntegral) val
    return val'

onceReadRetval :: Once -> IO (Ptr ())
onceReadRetval s = withManagedPtr s $ \ptr -> do
    val <- peek (ptr `plusPtr` 8) :: IO (Ptr ())
    return val

-- method Once::init_enter
-- method type : MemberFunction
-- Args : [Arg {argCName = "location", argType = TBasicType TVoid, direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, argCallerAllocates = False, transfer = TransferNothing}]
-- Lengths : []
-- returnType : TBasicType TBoolean
-- throws : False
-- Skip return : False

foreign import ccall "g_once_init_enter" g_once_init_enter :: 
    Ptr () ->                               -- location : TBasicType TVoid
    IO CInt


onceInitEnter ::
    (MonadIO m) =>
    Ptr ()                                  -- location
    -> m Bool                               -- result
onceInitEnter location = liftIO $ do
    result <- g_once_init_enter location
    let result' = (/= 0) result
    return result'

-- method Once::init_leave
-- method type : MemberFunction
-- Args : [Arg {argCName = "location", argType = TBasicType TVoid, direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, argCallerAllocates = False, transfer = TransferNothing},Arg {argCName = "result", argType = TBasicType TUInt64, direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, argCallerAllocates = False, transfer = TransferNothing}]
-- Lengths : []
-- returnType : TBasicType TVoid
-- throws : False
-- Skip return : False

foreign import ccall "g_once_init_leave" g_once_init_leave :: 
    Ptr () ->                               -- location : TBasicType TVoid
    Word64 ->                               -- result : TBasicType TUInt64
    IO ()


onceInitLeave ::
    (MonadIO m) =>
    Ptr ()                                  -- location
    -> Word64                               -- result_
    -> m ()                                 -- result
onceInitLeave location result_ = liftIO $ do
    g_once_init_leave location result_
    return ()

type family ResolveOnceMethod (t :: Symbol) (o :: *) :: * where
    ResolveOnceMethod l o = MethodResolutionFailed l o

instance (info ~ ResolveOnceMethod t Once, MethodInfo info Once p) => IsLabelProxy t (Once -> p) where
    fromLabelProxy _ = overloadedMethod (MethodProxy :: MethodProxy info)

#if MIN_VERSION_base(4,9,0)
instance (info ~ ResolveOnceMethod t Once, MethodInfo info Once p) => IsLabel t (Once -> p) where
    fromLabel _ = overloadedMethod (MethodProxy :: MethodProxy info)
#endif