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|
{-# LANGUAGE DeriveDataTypeable, ExistentialQuantification, TypeSynonymInstances, MultiParamTypeClasses, FlexibleInstances, PatternGuards #-}
module Storage ( StoreData
, Storage
, storage
, getStoreData
, setStoreData
, updateStoreData
) where
import XMonad
import qualified XMonad.StackSet as W
import XMonad.Layout.LayoutModifier (LayoutModifier(..), ModifiedLayout(..))
import Control.Applicative ((<$>))
import Control.Monad
import Data.IORef
import Data.Maybe
import Data.Typeable
class (Typeable d, Show d, Read d) => StoreData d
data (StoreData d) => StorageMessage d = GetStoreData (IORef (Maybe d)) | SetStoreData d
deriving Typeable
instance (StoreData d) => Message (StorageMessage d)
data (StoreData d) => Storage d a = Storage d deriving (Show, Read)
instance (StoreData d) => LayoutModifier (Storage d) a where
modifierDescription _ = "Storage"
handleMess (Storage d) m
| Just (GetStoreData ref) <- fromMessage m = do
io $ writeIORef ref $ Just d
return $ Nothing
| Just (SetStoreData d') <- fromMessage m = do
return $ Just $ Storage d'
handleMess _ _ = return Nothing
storage :: (LayoutClass l a, StoreData d) => d -> l a -> ModifiedLayout (Storage d) l a
storage def = ModifiedLayout $ Storage def
sendMessage' :: Message a => a -> X ()
sendMessage' a = W.workspace . W.current <$> gets windowset >>= sendMessageWithNoRefresh a
getStoreData :: StoreData d => X (Maybe d)
getStoreData = do
ref <- io . newIORef $ Nothing
sendMessage' $ GetStoreData ref
io . readIORef $ ref
setStoreData :: StoreData d => d -> X ()
setStoreData = broadcastMessage . SetStoreData
updateStoreData :: StoreData d => (d -> d) -> X ()
updateStoreData f = do
d <- getStoreData
when (isJust d) $ setStoreData . f $ fromJust d
|
