module Language.Java.Paragon.TypeCheck.Uniq 
    ( Uniq, initUniq, getUniq, newAlias, newFresh ) where

import Data.IORef

import Language.Java.Paragon.TypeCheck.Actors

newtype Uniq = Uniq (IORef Int)

initUniq :: IO Uniq
initUniq = newIORef 0 >>= return . Uniq

getUniq :: Uniq -> IO Int
getUniq (Uniq u) = do i <- readIORef u
                      writeIORef u (i+1)
                      return i


newAlias :: Uniq -> IO ActorId
newAlias u = do uniq <- getUniq u
                return $ Alias uniq

newFresh :: Uniq -> IO ActorId
newFresh u = do uniq <- getUniq u
                return $ Fresh uniq