Data.hs


{- |
Copyright  : Will Thompson, Iñaki García Etxebarria and Jonas Platte
License    : LGPL-2.1
Maintainer : Iñaki García Etxebarria (inaki@blueleaf.cc)

The 'GI.GLib.Structs.Data.Data' struct is an opaque data structure to represent a
[Keyed Data List][glib-Keyed-Data-Lists]. It should only be
accessed via the following functions.
-}

#define ENABLE_OVERLOADING (MIN_VERSION_haskell_gi_overloading(1,0,0) \
       && !defined(__HADDOCK_VERSION__))

module GI.GLib.Structs.Data
    ( 

-- * Exported types
    Data(..)                                ,
    noData                                  ,


    ) where

import Data.GI.Base.ShortPrelude
import qualified Data.GI.Base.ShortPrelude as SP
import qualified Data.GI.Base.Overloading as O
import qualified Prelude as P

import qualified Data.GI.Base.Attributes as GI.Attributes
import qualified Data.GI.Base.ManagedPtr as B.ManagedPtr
import qualified Data.GI.Base.GClosure as B.GClosure
import qualified Data.GI.Base.GError as B.GError
import qualified Data.GI.Base.GVariant as B.GVariant
import qualified Data.GI.Base.GValue as B.GValue
import qualified Data.GI.Base.GParamSpec as B.GParamSpec
import qualified Data.GI.Base.CallStack as B.CallStack
import qualified Data.GI.Base.Properties as B.Properties
import qualified Data.Text as T
import qualified Data.ByteString.Char8 as B
import qualified Data.Map as Map
import qualified Foreign.Ptr as FP
import qualified GHC.OverloadedLabels as OL


-- | Memory-managed wrapper type.
newtype Data = Data (ManagedPtr Data)
-- XXX Wrapping a foreign struct/union with no known destructor or size, leak?
instance WrappedPtr Data where
    wrappedPtrCalloc = return nullPtr
    wrappedPtrCopy = return
    wrappedPtrFree = Nothing

-- | A convenience alias for `Nothing` :: `Maybe` `Data`.
noData :: Maybe Data
noData = Nothing


#if ENABLE_OVERLOADING
instance O.HasAttributeList Data
type instance O.AttributeList Data = DataAttributeList
type DataAttributeList = ('[ ] :: [(Symbol, *)])
#endif

#if ENABLE_OVERLOADING
type family ResolveDataMethod (t :: Symbol) (o :: *) :: * where
    ResolveDataMethod l o = O.MethodResolutionFailed l o

instance (info ~ ResolveDataMethod t Data, O.MethodInfo info Data p) => OL.IsLabel t (Data -> p) where
#if MIN_VERSION_base(4,10,0)
    fromLabel = O.overloadedMethod (O.MethodProxy :: O.MethodProxy info)
#else
    fromLabel _ = O.overloadedMethod (O.MethodProxy :: O.MethodProxy info)
#endif

#endif