{-# OPTIONS_GHC -funbox-strict-fields #-}
module Data.UnionFind.IO
( Point, fresh, repr, union, union', equivalent, redundant,
descriptor, setDescriptor, modifyDescriptor )
where
import Data.IORef
import Control.Monad ( when )
import Control.Applicative
newtype Point a = Pt (IORef (Link a)) deriving Point a -> Point a -> Bool
forall a. Point a -> Point a -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: Point a -> Point a -> Bool
$c/= :: forall a. Point a -> Point a -> Bool
== :: Point a -> Point a -> Bool
$c== :: forall a. Point a -> Point a -> Bool
Eq
data Link a
= Info {-# UNPACK #-} !(IORef (Info a))
| Link {-# UNPACK #-} !(Point a)
deriving Link a -> Link a -> Bool
forall a. Link a -> Link a -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: Link a -> Link a -> Bool
$c/= :: forall a. Link a -> Link a -> Bool
== :: Link a -> Link a -> Bool
$c== :: forall a. Link a -> Link a -> Bool
Eq
data Info a = MkInfo
{ forall a. Info a -> Int
weight :: {-# UNPACK #-} !Int
, forall a. Info a -> a
descr :: a
} deriving Info a -> Info a -> Bool
forall a. Eq a => Info a -> Info a -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: Info a -> Info a -> Bool
$c/= :: forall a. Eq a => Info a -> Info a -> Bool
== :: Info a -> Info a -> Bool
$c== :: forall a. Eq a => Info a -> Info a -> Bool
Eq
fresh :: a -> IO (Point a)
fresh :: forall a. a -> IO (Point a)
fresh a
desc = do
IORef (Info a)
info <- forall a. a -> IO (IORef a)
newIORef (MkInfo { weight :: Int
weight = Int
1, descr :: a
descr = a
desc })
IORef (Link a)
l <- forall a. a -> IO (IORef a)
newIORef (forall a. IORef (Info a) -> Link a
Info IORef (Info a)
info)
forall (m :: * -> *) a. Monad m => a -> m a
return (forall a. IORef (Link a) -> Point a
Pt IORef (Link a)
l)
repr :: Point a -> IO (Point a)
repr :: forall a. Point a -> IO (Point a)
repr point :: Point a
point@(Pt IORef (Link a)
l) = do
Link a
link <- forall a. IORef a -> IO a
readIORef IORef (Link a)
l
case Link a
link of
Info IORef (Info a)
_ -> forall (m :: * -> *) a. Monad m => a -> m a
return Point a
point
Link pt' :: Point a
pt'@(Pt IORef (Link a)
l') -> do
Point a
pt'' <- forall a. Point a -> IO (Point a)
repr Point a
pt'
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Point a
pt'' forall a. Eq a => a -> a -> Bool
/= Point a
pt') forall a b. (a -> b) -> a -> b
$ do
Link a
link' <- forall a. IORef a -> IO a
readIORef IORef (Link a)
l'
forall a. IORef a -> a -> IO ()
writeIORef IORef (Link a)
l Link a
link'
forall (m :: * -> *) a. Monad m => a -> m a
return Point a
pt''
descrRef :: Point a -> IO (IORef (Info a))
descrRef :: forall a. Point a -> IO (IORef (Info a))
descrRef point :: Point a
point@(Pt IORef (Link a)
link_ref) = do
Link a
link <- forall a. IORef a -> IO a
readIORef IORef (Link a)
link_ref
case Link a
link of
Info IORef (Info a)
info -> forall (m :: * -> *) a. Monad m => a -> m a
return IORef (Info a)
info
Link (Pt IORef (Link a)
link'_ref) -> do
Link a
link' <- forall a. IORef a -> IO a
readIORef IORef (Link a)
link'_ref
case Link a
link' of
Info IORef (Info a)
info -> forall (m :: * -> *) a. Monad m => a -> m a
return IORef (Info a)
info
Link a
_ -> forall a. Point a -> IO (IORef (Info a))
descrRef forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< forall a. Point a -> IO (Point a)
repr Point a
point
descriptor :: Point a -> IO a
descriptor :: forall a. Point a -> IO a
descriptor Point a
point = do
forall a. Info a -> a
descr forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (forall a. IORef a -> IO a
readIORef forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< forall a. Point a -> IO (IORef (Info a))
descrRef Point a
point)
setDescriptor :: Point a -> a -> IO ()
setDescriptor :: forall a. Point a -> a -> IO ()
setDescriptor Point a
point a
new_descr = do
IORef (Info a)
r <- forall a. Point a -> IO (IORef (Info a))
descrRef Point a
point
forall a. IORef a -> (a -> a) -> IO ()
modifyIORef IORef (Info a)
r forall a b. (a -> b) -> a -> b
$ \Info a
i -> Info a
i { descr :: a
descr = a
new_descr }
modifyDescriptor :: Point a -> (a -> a) -> IO ()
modifyDescriptor :: forall a. Point a -> (a -> a) -> IO ()
modifyDescriptor Point a
point a -> a
f = do
IORef (Info a)
r <- forall a. Point a -> IO (IORef (Info a))
descrRef Point a
point
forall a. IORef a -> (a -> a) -> IO ()
modifyIORef IORef (Info a)
r forall a b. (a -> b) -> a -> b
$ \Info a
i -> Info a
i { descr :: a
descr = a -> a
f (forall a. Info a -> a
descr Info a
i) }
union :: Point a -> Point a -> IO ()
union :: forall a. Point a -> Point a -> IO ()
union Point a
p1 Point a
p2 = forall a. Point a -> Point a -> (a -> a -> IO a) -> IO ()
union' Point a
p1 Point a
p2 (\a
_ a
d2 -> forall (m :: * -> *) a. Monad m => a -> m a
return a
d2)
union' :: Point a -> Point a -> (a -> a -> IO a) -> IO ()
union' :: forall a. Point a -> Point a -> (a -> a -> IO a) -> IO ()
union' Point a
p1 Point a
p2 a -> a -> IO a
update = do
point1 :: Point a
point1@(Pt IORef (Link a)
link_ref1) <- forall a. Point a -> IO (Point a)
repr Point a
p1
point2 :: Point a
point2@(Pt IORef (Link a)
link_ref2) <- forall a. Point a -> IO (Point a)
repr Point a
p2
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Point a
point1 forall a. Eq a => a -> a -> Bool
/= Point a
point2) forall a b. (a -> b) -> a -> b
$ do
Info IORef (Info a)
info_ref1 <- forall a. IORef a -> IO a
readIORef IORef (Link a)
link_ref1
Info IORef (Info a)
info_ref2 <- forall a. IORef a -> IO a
readIORef IORef (Link a)
link_ref2
MkInfo Int
w1 a
d1 <- forall a. IORef a -> IO a
readIORef IORef (Info a)
info_ref1
MkInfo Int
w2 a
d2 <- forall a. IORef a -> IO a
readIORef IORef (Info a)
info_ref2
a
d2' <- a -> a -> IO a
update a
d1 a
d2
if Int
w1 forall a. Ord a => a -> a -> Bool
>= Int
w2 then do
forall a. IORef a -> a -> IO ()
writeIORef IORef (Link a)
link_ref2 (forall a. Point a -> Link a
Link Point a
point1)
forall a. IORef a -> a -> IO ()
writeIORef IORef (Info a)
info_ref1 (forall a. Int -> a -> Info a
MkInfo (Int
w1 forall a. Num a => a -> a -> a
+ Int
w2) a
d2')
else do
forall a. IORef a -> a -> IO ()
writeIORef IORef (Link a)
link_ref1 (forall a. Point a -> Link a
Link Point a
point2)
forall a. IORef a -> a -> IO ()
writeIORef IORef (Info a)
info_ref2 (forall a. Int -> a -> Info a
MkInfo (Int
w1 forall a. Num a => a -> a -> a
+ Int
w2) a
d2')
equivalent :: Point a -> Point a -> IO Bool
equivalent :: forall a. Point a -> Point a -> IO Bool
equivalent Point a
p1 Point a
p2 = forall a. Eq a => a -> a -> Bool
(==) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall a. Point a -> IO (Point a)
repr Point a
p1 forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> forall a. Point a -> IO (Point a)
repr Point a
p2
redundant :: Point a -> IO Bool
redundant :: forall a. Point a -> IO Bool
redundant (Pt IORef (Link a)
link_r) = do
Link a
link <- forall a. IORef a -> IO a
readIORef IORef (Link a)
link_r
case Link a
link of
Info IORef (Info a)
_ -> forall (m :: * -> *) a. Monad m => a -> m a
return Bool
False
Link Point a
_ -> forall (m :: * -> *) a. Monad m => a -> m a
return Bool
True