content: {-# LANGUAGE BangPatterns, CPP #-}
  
  #if __GLASGOW_HASKELL__ >= 702
  {-# LANGUAGE Trustworthy #-}
  #endif
  
  ------------------------------------------------------------------------
  -- |
  -- Module      :  Data.HashMap.Strict
  -- Copyright   :  2010-2012 Johan Tibell
  -- License     :  BSD-style
  -- Maintainer  :  johan.tibell@gmail.com
  -- Stability   :  provisional
  -- Portability :  portable
  --
  -- A map from /hashable/ keys to values.  A map cannot contain
  -- duplicate keys; each key can map to at most one value.  A 'HashMap'
  -- makes no guarantees as to the order of its elements.
  --
  -- This map is strict in both the keys and the values; keys and values
  -- are evaluated to /weak head normal form/ before they are added to
  -- the map.  Exception: the provided instances are the same as for the
  -- lazy version of this module.
  --
  -- The implementation is based on /hash array mapped tries/.  A
  -- 'HashMap' is often faster than other tree-based set types,
  -- especially when key comparison is expensive, as in the case of
  -- strings.
  --
  -- Many operations have a average-case complexity of /O(log n)/.  The
  -- implementation uses a large base (i.e. 16) so in practice these
  -- operations are constant time.
  module Data.HashMap.Strict
      (
        HashMap
  
        -- * Construction
      , empty
      , singleton
  
        -- * Basic interface
      , HM.null
      , size
      , HM.member
      , HM.lookup
      , lookupDefault
      , (!)
      , insert
      , insertWith
      , delete
      , adjust
  
        -- * Combine
        -- ** Union
      , union
      , unionWith
      , unions
  
        -- * Transformations
      , map
      , traverseWithKey
  
        -- * Difference and intersection
      , difference
      , intersection
  
        -- * Folds
      , foldl'
      , foldlWithKey'
      , HM.foldr
      , foldrWithKey
  
        -- * Filter
      , HM.filter
      , filterWithKey
  
        -- * Conversions
      , keys
      , elems
  
        -- ** Lists
      , toList
      , fromList
      , fromListWith
      ) where
  
  import Control.Monad.ST (runST)
  import Data.Bits ((.&.), (.|.))
  import qualified Data.List as L
  import Data.Hashable (Hashable)
  import Prelude hiding (map)
  
  import qualified Data.HashMap.Array as A
  import qualified Data.HashMap.Base as HM
  import Data.HashMap.Base hiding (
      adjust, fromList, fromListWith, insert, insertWith, map, singleton,
      unionWith)
  
  ------------------------------------------------------------------------
  -- * Construction
  
  -- | /O(1)/ Construct a map with a single element.
  singleton :: (Hashable k) => k -> v -> HashMap k v
  singleton k !v = HM.singleton k v
  
  ------------------------------------------------------------------------
  -- * Basic interface
  
  -- | /O(log n)/ Associate the specified value with the specified
  -- key in this map.  If this map previously contained a mapping for
  -- the key, the old value is replaced.
  insert :: (Eq k, Hashable k) => k -> v -> HashMap k v -> HashMap k v
  insert k !v = HM.insert k v
  #if __GLASGOW_HASKELL__ >= 700
  {-# INLINABLE insert #-}
  #endif
  
  -- | /O(log n)/ Associate the value with the key in this map.  If
  -- this map previously contained a mapping for the key, the old value
  -- is replaced by the result of applying the given function to the new
  -- and old value.  Example:
  --
  -- > insertWith f k v map
  -- >   where f new old = new + old
  insertWith :: (Eq k, Hashable k) => (v -> v -> v) -> k -> v -> HashMap k v
             -> HashMap k v
  insertWith f k0 !v0 m0 = runST (go h0 k0 v0 0 m0)
    where
      h0 = hash k0
      go !h !k x !_ Empty = return $ Leaf h (L k x)
      go h k x s (Leaf hy l@(L ky y))
          | hy == h = if ky == k
                      then let !v' = f x y in return $! Leaf h (L k v')
                      else return $! collision h l (L k x)
          | otherwise = two s h k x hy ky y
      go h k x s (BitmapIndexed b ary)
          | b .&. m == 0 = do
              ary' <- A.insert' ary i $! Leaf h (L k x)
              return $! bitmapIndexedOrFull (b .|. m) ary'
          | otherwise = do
              st <- A.index_ ary i
              st' <- go h k x (s+bitsPerSubkey) st
              ary' <- A.update' ary i st'
              return $! BitmapIndexed b ary'
        where m = mask h s
              i = sparseIndex b m
      go h k x s (Full ary) = do
          st <- A.index_ ary i
          st' <- go h k x (s+bitsPerSubkey) st
          ary' <- update16' ary i st'
          return $! Full ary'
        where i = index h s
      go h k x s t@(Collision hy v)
          | h == hy   = return $! Collision h (updateOrSnocWith f k x v)
          | otherwise = go h k x s $ BitmapIndexed (mask hy s) (A.singleton t)
  #if __GLASGOW_HASKELL__ >= 700
  {-# INLINABLE insertWith #-}
  #endif
  
  -- | In-place update version of insertWith
  unsafeInsertWith :: (Eq k, Hashable k) => (v -> v -> v) -> k -> v -> HashMap k v
                   -> HashMap k v
  unsafeInsertWith f k0 v0 m0 = runST (go h0 k0 v0 0 m0)
    where
      h0 = hash k0
      go !h !k x !_ Empty = return $! Leaf h (L k x)
      go h k x s (Leaf hy l@(L ky y))
          | hy == h = if ky == k
                      then let !v' = f x y in return $! Leaf h (L k v')
                      else return $! collision h l (L k x)
          | otherwise = two s h k x hy ky y
      go h k x s t@(BitmapIndexed b ary)
          | b .&. m == 0 = do
              ary' <- A.insert' ary i $! Leaf h (L k x)
              return $! bitmapIndexedOrFull (b .|. m) ary'
          | otherwise = do
              st <- A.index_ ary i
              st' <- go h k x (s+bitsPerSubkey) st
              A.unsafeUpdate' ary i st'
              return t
        where m = mask h s
              i = sparseIndex b m
      go h k x s t@(Full ary) = do
          st <- A.index_ ary i
          st' <- go h k x (s+bitsPerSubkey) st
          A.unsafeUpdate' ary i st'
          return t
        where i = index h s
      go h k x s t@(Collision hy v)
          | h == hy   = return $! Collision h (updateOrSnocWith f k x v)
          | otherwise = go h k x s $ BitmapIndexed (mask hy s) (A.singleton t)
  #if __GLASGOW_HASKELL__ >= 700
  {-# INLINABLE unsafeInsertWith #-}
  #endif
  
  -- | /O(log n)/ Adjust the value tied to a given key in this map only
  -- if it is present. Otherwise, leave the map alone.
  adjust :: (Eq k, Hashable k) => (v -> v) -> k -> HashMap k v -> HashMap k v
  adjust f k0 = go h0 k0 0
    where
      h0 = hash k0
      go !_ !_ !_ Empty = Empty
      go h k _ t@(Leaf hy (L ky y))
          | hy == h && ky == k = let !v' = f y in Leaf h (L k v')
          | otherwise          = t
      go h k s t@(BitmapIndexed b ary)
          | b .&. m == 0 = t
          | otherwise = let st   = A.index ary i
                            st'  = go h k (s+bitsPerSubkey) st
                            ary' = A.update ary i $! st'
                        in BitmapIndexed b ary'
        where m = mask h s
              i = sparseIndex b m
      go h k s (Full ary) =
          let i    = index h s
              st   = A.index ary i
              st'  = go h k (s+bitsPerSubkey) st
              ary' = update16 ary i $! st'
          in Full ary'
      go h k _ t@(Collision hy v)
          | h == hy   = Collision h (updateWith f k v)
          | otherwise = t
  #if __GLASGOW_HASKELL__ >= 700
  {-# INLINABLE adjust #-}
  #endif
  
  ------------------------------------------------------------------------
  -- * Combine
  
  -- | /O(n+m)/ The union of two maps.  If a key occurs in both maps,
  -- the provided function (first argument) will be used to compute the result.
  unionWith :: (Eq k, Hashable k) => (v -> v -> v) -> HashMap k v -> HashMap k v
            -> HashMap k v
  unionWith f = go 0
    where
      -- empty vs. anything
      go !_ t1 Empty = t1
      go _ Empty t2 = t2
      -- leaf vs. leaf
      go s t1@(Leaf h1 l1@(L k1 v1)) t2@(Leaf h2 l2@(L k2 v2))
          | h1 == h2  = if k1 == k2
                        then Leaf h1 . L k1 $! f v1 v2
                        else collision h1 l1 l2
          | otherwise = goDifferentHash s h1 h2 t1 t2
      go s t1@(Leaf h1 (L k1 v1)) t2@(Collision h2 ls2)
          | h1 == h2  = Collision h1 (updateOrSnocWith f k1 v1 ls2)
          | otherwise = goDifferentHash s h1 h2 t1 t2
      go s t1@(Collision h1 ls1) t2@(Leaf h2 (L k2 v2))
          | h1 == h2  = Collision h1 (updateOrSnocWith (flip f) k2 v2 ls1)
          | otherwise = goDifferentHash s h1 h2 t1 t2
      go s t1@(Collision h1 ls1) t2@(Collision h2 ls2)
          | h1 == h2  = Collision h1 (updateOrConcatWith f ls1 ls2)
          | otherwise = goDifferentHash s h1 h2 t1 t2
      -- branch vs. branch
      go s (BitmapIndexed b1 ary1) (BitmapIndexed b2 ary2) =
          let b'   = b1 .|. b2
              ary' = unionArrayBy (go (s+bitsPerSubkey)) b1 b2 ary1 ary2
          in bitmapIndexedOrFull b' ary'
      go s (BitmapIndexed b1 ary1) (Full ary2) =
          let ary' = unionArrayBy (go (s+bitsPerSubkey)) b1 fullNodeMask ary1 ary2
          in Full ary'
      go s (Full ary1) (BitmapIndexed b2 ary2) =
          let ary' = unionArrayBy (go (s+bitsPerSubkey)) fullNodeMask b2 ary1 ary2
          in Full ary'
      go s (Full ary1) (Full ary2) =
          let ary' = unionArrayBy (go (s+bitsPerSubkey)) fullNodeMask fullNodeMask
                     ary1 ary2
          in Full ary'
      -- leaf vs. branch
      go s (BitmapIndexed b1 ary1) t2
          | b1 .&. m2 == 0 = let ary' = A.insert ary1 i t2
                                 b'   = b1 .|. m2
                             in bitmapIndexedOrFull b' ary'
          | otherwise      = let ary' = A.updateWith ary1 i $ \st1 ->
                                     go (s+bitsPerSubkey) st1 t2
                             in BitmapIndexed b1 ary'
          where
            h2 = leafHashCode t2
            m2 = mask h2 s
            i = sparseIndex b1 m2
      go s t1 (BitmapIndexed b2 ary2)
          | b2 .&. m1 == 0 = let ary' = A.insert ary2 i $! t1
                                 b'   = b2 .|. m1
                             in bitmapIndexedOrFull b' ary'
          | otherwise      = let ary' = A.updateWith ary2 i $ \st2 ->
                                     go (s+bitsPerSubkey) t1 st2
                             in BitmapIndexed b2 ary'
        where
          h1 = leafHashCode t1
          m1 = mask h1 s
          i = sparseIndex b2 m1
      go s (Full ary1) t2 =
          let h2   = leafHashCode t2
              i    = index h2 s
              ary' = update16With ary1 i $ \st1 -> go (s+bitsPerSubkey) st1 t2
          in Full ary'
      go s t1 (Full ary2) =
          let h1   = leafHashCode t1
              i    = index h1 s
              ary' = update16With ary2 i $ \st2 -> go (s+bitsPerSubkey) t1 st2
          in Full ary'
  
      leafHashCode (Leaf h _) = h
      leafHashCode (Collision h _) = h
      leafHashCode _ = error "leafHashCode"
  
      goDifferentHash s h1 h2 t1 t2
          | m1 == m2  = BitmapIndexed m1 (A.singleton $! go (s+bitsPerSubkey) t1 t2)
          | m1 <  m2  = BitmapIndexed (m1 .|. m2) (A.pair t1 t2)
          | otherwise = BitmapIndexed (m1 .|. m2) (A.pair t2 t1)
        where
          m1 = mask h1 s
          m2 = mask h2 s
  {-# INLINE unionWith #-}
  
  ------------------------------------------------------------------------
  -- * Transformations
  
  -- | /O(n)/ Transform this map by applying a function to every value.
  map :: (v1 -> v2) -> HashMap k v1 -> HashMap k v2
  map f = go
    where
      go Empty                 = Empty
      go (Leaf h (L k v))      = let !v' = f v in Leaf h $ L k v'
      go (BitmapIndexed b ary) = BitmapIndexed b $ A.map' go ary
      go (Full ary)            = Full $ A.map' go ary
      go (Collision h ary)     =
          Collision h $ A.map' (\ (L k v) -> let !v' = f v in L k v') ary
  {-# INLINE map #-}
  
  -- TODO: Should we add a strict traverseWithKey?
  
  ------------------------------------------------------------------------
  -- ** Lists
  
  -- | /O(n*log n)/ Construct a map with the supplied mappings.  If the
  -- list contains duplicate mappings, the later mappings take
  -- precedence.
  fromList :: (Eq k, Hashable k) => [(k, v)] -> HashMap k v
  fromList = L.foldl' (\ m (k, v) -> HM.unsafeInsert k v m) empty
  #if __GLASGOW_HASKELL__ >= 700
  {-# INLINABLE fromList #-}
  #endif
  
  -- | /O(n*log n)/ Construct a map from a list of elements.  Uses
  -- the provided function to merge duplicate entries.
  fromListWith :: (Eq k, Hashable k) => (v -> v -> v) -> [(k, v)] -> HashMap k v
  fromListWith f = L.foldl' (\ m (k, v) -> unsafeInsertWith f k v m) empty
  {-# INLINE fromListWith #-}
  
  ------------------------------------------------------------------------
  -- Array operations
  
  updateWith :: Eq k => (v -> v) -> k -> A.Array (Leaf k v) -> A.Array (Leaf k v)
  updateWith f k0 ary0 = go k0 ary0 0 (A.length ary0)
    where
      go !k !ary !i !n
          | i >= n    = ary
          | otherwise = case A.index ary i of
              (L kx y) | k == kx   -> let !v' = f y in A.update ary i (L k v')
                       | otherwise -> go k ary (i+1) n
  #if __GLASGOW_HASKELL__ >= 700
  {-# INLINABLE updateWith #-}
  #endif
  
  updateOrSnocWith :: Eq k => (v -> v -> v) -> k -> v -> A.Array (Leaf k v)
                   -> A.Array (Leaf k v)
  updateOrSnocWith f k0 v0 ary0 = go k0 v0 ary0 0 (A.length ary0)
    where
      go !k v !ary !i !n
          | i >= n = A.run $ do
              -- Not found, append to the end.
              mary <- A.new_ (n + 1)
              A.copy ary 0 mary 0 n
              A.write mary n (L k v)
              return mary
          | otherwise = case A.index ary i of
              (L kx y) | k == kx   -> let !v' = f v y in A.update ary i (L k v')
                       | otherwise -> go k v ary (i+1) n
  #if __GLASGOW_HASKELL__ >= 700
  {-# INLINABLE updateOrSnocWith #-}
  #endif
  