{-# OPTIONS -cpp #-}
-- #hide
module Distribution.Compat.Map (
   Map,
   member, lookup, findWithDefault,
   empty,
   insert, insertWith,
   update,
   union, unionWith, unions,
   difference,
   elems, keys,
   fromList, fromListWith,
   toAscList
) where

import Prelude hiding ( lookup )

#if __GLASGOW_HASKELL__ >= 603 || !__GLASGOW_HASKELL__
import Data.Map
#else
import Data.FiniteMap

type Map k a = FiniteMap k a

instance Functor (FiniteMap k) where
	fmap f = mapFM (const f)

member :: Ord k => k -> Map k a -> Bool
member = elemFM

lookup :: Ord k => k -> Map k a -> Maybe a
lookup = flip lookupFM

findWithDefault :: Ord k => a -> k -> Map k a -> a
findWithDefault a k m = lookupWithDefaultFM m a k

empty :: Map k a
empty = emptyFM

insert :: Ord k => k -> a -> Map k a -> Map k a
insert k a m = addToFM m k a

-- This might be able to use delFromFM, but I'm confused by the
--     IF_NOT_GHC(delFromFM COMMA)
-- in the Data.FiniteMap export list in ghc 6.2.
delete :: Ord k => k -> Map k a -> Map k a
delete k m = delListFromFM m [k]

insertWith :: Ord k => (a -> a -> a) -> k -> a -> Map k a -> Map k a
insertWith c k a m = addToFM_C (flip c) m k a

update :: Ord k => (a -> Maybe a) -> k -> Map k a -> Map k a
update f k m = case lookup k m of
  Nothing -> m
  Just a  -> case f a of
    Nothing -> delete k m
    Just a' -> insert k a' m

union :: Ord k => Map k a -> Map k a -> Map k a
union = flip plusFM

unionWith :: Ord k => (a -> a -> a) -> Map k a -> Map k a -> Map k a
unionWith c l r = plusFM_C (flip c) r l

unions :: Ord k => [Map k a] -> Map k a
unions = foldl (flip plusFM) emptyFM

difference :: Ord k => Map k a -> Map k b -> Map k a
difference m1 m2 = delListFromFM m1 (keys m2)
  -- minusFM wasn't polymorphic enough in GHC 6.2.x

elems :: Map k a -> [a]
elems = eltsFM

keys :: Map k a -> [k]
keys = keysFM

fromList :: Ord k => [(k,a)] -> Map k a
fromList = listToFM

fromListWith :: Ord k => (a -> a -> a) -> [(k,a)] -> Map k a 
fromListWith c = addListToFM_C (flip c) emptyFM

toAscList :: Map k a -> [(k,a)]
toAscList = fmToList
#endif