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Introduce 'hashOfLeafOrCollision' #550

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c07029d
Introduce 'hashOfLeafOrCollision'
sjakobi Nov 13, 2025
fb7c3d0
differenceWithKey: Use hashOfLeafOrCollision
sjakobi Nov 13, 2025
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100 changes: 43 additions & 57 deletions Data/HashMap/Internal.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -146,6 +146,7 @@ module Data.HashMap.Internal
, deleteKeyExists
, insertModifying
, ptrEq
, hashOfLeafOrCollision
, adjust#
) where

Expand Down Expand Up @@ -1625,7 +1626,7 @@ unionWithKey f = go 0
go (nextShift s) st1 t2
in BitmapIndexed b1 ary'
where
h2 = leafHashCode t2
h2 = hashOfLeafOrCollision t2
m2 = mask h2 s
i = sparseIndex b1 m2
go s t1 (BitmapIndexed b2 ary2)
Expand All @@ -1636,24 +1637,20 @@ unionWithKey f = go 0
go (nextShift s) t1 st2
in BitmapIndexed b2 ary'
where
h1 = leafHashCode t1
h1 = hashOfLeafOrCollision t1
m1 = mask h1 s
i = sparseIndex b2 m1
go s (Full ary1) t2 =
let h2 = leafHashCode t2
let h2 = hashOfLeafOrCollision t2
i = index h2 s
ary' = updateFullArrayWith' ary1 i $ \st1 -> go (nextShift s) st1 t2
in Full ary'
go s t1 (Full ary2) =
let h1 = leafHashCode t1
let h1 = hashOfLeafOrCollision t1
i = index h1 s
ary' = updateFullArrayWith' ary2 i $ \st2 -> go (nextShift s) 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 $! goDifferentHash (nextShift s) h1 h2 t1 t2)
| m1 < m2 = BitmapIndexed (m1 .|. m2) (A.pair t1 t2)
Expand Down Expand Up @@ -1942,7 +1939,26 @@ differenceWithKey f = go_differenceWithKey 0
go_differenceWithKey _s a@(Collision hA aryA) (Leaf hB (L kB vB))
| hA == hB = updateCollision (\vA -> f kB vA vB) hA kB aryA a
| otherwise = a
go_differenceWithKey s a@(BitmapIndexed bA aryA) b@(Leaf hB _)
go_differenceWithKey s a@(Collision hA _) (BitmapIndexed bB aryB)
| bB .&. m == 0 = a
| otherwise =
case A.index# aryB (sparseIndex bB m) of
(# stB #) -> go_differenceWithKey (nextShift s) a stB
where m = mask hA s
go_differenceWithKey s a@(Collision hA _) (Full aryB)
= case A.index# aryB (index hA s) of
(# stB #) -> go_differenceWithKey (nextShift s) a stB
go_differenceWithKey s a@(BitmapIndexed bA aryA) (BitmapIndexed bB aryB)
= differenceWithKey_Arrays s bA aryA a bB aryB
go_differenceWithKey s a@(Full aryA) (BitmapIndexed bB aryB)
= differenceWithKey_Arrays s fullBitmap aryA a bB aryB
go_differenceWithKey s a@(BitmapIndexed bA aryA) (Full aryB)
= differenceWithKey_Arrays s bA aryA a fullBitmap aryB
go_differenceWithKey s a@(Full aryA) (Full aryB)
= differenceWithKey_Arrays s fullBitmap aryA a fullBitmap aryB
go_differenceWithKey _s a@(Collision hA aryA) (Collision hB aryB)
= differenceWithKey_Collisions f hA aryA a hB aryB
go_differenceWithKey s a@(BitmapIndexed bA aryA) b
| bA .&. m == 0 = a
| otherwise = case A.index# aryA i of
(# !stA #) -> case go_differenceWithKey (nextShift s) stA b of
Expand All @@ -1956,26 +1972,10 @@ differenceWithKey f = go_differenceWithKey 0
| stA `ptrEq` stA' -> a
| otherwise -> BitmapIndexed bA (A.update aryA i stA')
where
hB = hashOfLeafOrCollision b
m = mask hB s
i = sparseIndex bA m
go_differenceWithKey s a@(BitmapIndexed bA aryA) b@(Collision hB _)
| bA .&. m == 0 = a
| otherwise =
case A.index# aryA i of
(# !st #) -> case go_differenceWithKey (nextShift s) st b of
Empty | A.length aryA == 2
, (# l #) <- A.index# aryA (otherOfOneOrZero i)
, isLeafOrCollision l
-> l
| otherwise
-> BitmapIndexed (bA .&. complement m) (A.delete aryA i)
st' | isLeafOrCollision st' && A.length aryA == 1 -> st'
| st `ptrEq` st' -> a
| otherwise -> BitmapIndexed bA (A.update aryA i st')
where
m = mask hB s
i = sparseIndex bA m
go_differenceWithKey s a@(Full aryA) b@(Leaf hB _)
go_differenceWithKey s a@(Full aryA) b
= case A.index# aryA i of
(# !stA #) -> case go_differenceWithKey (nextShift s) stA b of
Empty ->
Expand All @@ -1984,36 +1984,9 @@ differenceWithKey f = go_differenceWithKey 0
in BitmapIndexed bm aryA'
stA' | stA `ptrEq` stA' -> a
| otherwise -> Full (updateFullArray aryA i stA')
where i = index hB s
go_differenceWithKey s a@(Full aryA) b@(Collision hB _)
= case A.index# aryA i of
(# !stA #) -> case go_differenceWithKey (nextShift s) stA b of
Empty ->
let aryA' = A.delete aryA i
bm = fullBitmap .&. complement (1 `unsafeShiftL` i)
in BitmapIndexed bm aryA'
stA' | stA `ptrEq` stA' -> a
| otherwise -> Full (updateFullArray aryA i stA')
where i = index hB s
go_differenceWithKey s a@(Collision hA _) (BitmapIndexed bB aryB)
| bB .&. m == 0 = a
| otherwise =
case A.index# aryB (sparseIndex bB m) of
(# stB #) -> go_differenceWithKey (nextShift s) a stB
where m = mask hA s
go_differenceWithKey s a@(Collision hA _) (Full aryB)
= case A.index# aryB (index hA s) of
(# stB #) -> go_differenceWithKey (nextShift s) a stB
go_differenceWithKey s a@(BitmapIndexed bA aryA) (BitmapIndexed bB aryB)
= differenceWithKey_Arrays s bA aryA a bB aryB
go_differenceWithKey s a@(Full aryA) (BitmapIndexed bB aryB)
= differenceWithKey_Arrays s fullBitmap aryA a bB aryB
go_differenceWithKey s a@(BitmapIndexed bA aryA) (Full aryB)
= differenceWithKey_Arrays s bA aryA a fullBitmap aryB
go_differenceWithKey s a@(Full aryA) (Full aryB)
= differenceWithKey_Arrays s fullBitmap aryA a fullBitmap aryB
go_differenceWithKey _s a@(Collision hA aryA) (Collision hB aryB)
= differenceWithKey_Collisions f hA aryA a hB aryB
where
hB = hashOfLeafOrCollision b
i = index hB s

differenceWithKey_Arrays !s !bA !aryA tA !bB !aryB
| bA .&. bB == 0 = tA
Expand Down Expand Up @@ -2841,6 +2814,19 @@ otherOfOneOrZero :: Int -> Int
otherOfOneOrZero i = 1 - i
{-# INLINE otherOfOneOrZero #-}

------------------------------------------------------------------------
-- Tools for reducing duplication in code handling 'Leaf' and 'Collision' nodes

-- | The 'Hash' of a 'Leaf' or 'Collision' node.
--
-- This function is marked @NOINLINE@ to prevent GHC from generating separate
-- alternatives for 'Leaf' and 'Collision' nodes.
hashOfLeafOrCollision :: HashMap k v -> Hash
hashOfLeafOrCollision (Leaf h _) = h
hashOfLeafOrCollision (Collision h _) = h
hashOfLeafOrCollision _ = error "hashOfLeafOrCollision"
{-# NOINLINE hashOfLeafOrCollision #-}

------------------------------------------------------------------------
-- IsList instance
instance (Eq k, Hashable k) => Exts.IsList (HashMap k v) where
Expand Down
12 changes: 4 additions & 8 deletions Data/HashMap/Internal/Strict.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -505,7 +505,7 @@ unionWithKey f = go 0
go (nextShift s) st1 t2
in BitmapIndexed b1 ary'
where
h2 = leafHashCode t2
h2 = HM.hashOfLeafOrCollision t2
m2 = mask h2 s
i = sparseIndex b1 m2
go s t1 (BitmapIndexed b2 ary2)
Expand All @@ -516,24 +516,20 @@ unionWithKey f = go 0
go (nextShift s) t1 st2
in BitmapIndexed b2 ary'
where
h1 = leafHashCode t1
h1 = HM.hashOfLeafOrCollision t1
m1 = mask h1 s
i = sparseIndex b2 m1
go s (Full ary1) t2 =
let h2 = leafHashCode t2
let h2 = HM.hashOfLeafOrCollision t2
i = index h2 s
ary' = HM.updateFullArrayWith' ary1 i $ \st1 -> go (nextShift s) st1 t2
in Full ary'
go s t1 (Full ary2) =
let h1 = leafHashCode t1
let h1 = HM.hashOfLeafOrCollision t1
i = index h1 s
ary' = HM.updateFullArrayWith' ary2 i $ \st2 -> go (nextShift s) 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 $! goDifferentHash (nextShift s) h1 h2 t1 t2)
| m1 < m2 = BitmapIndexed (m1 .|. m2) (A.pair t1 t2)
Expand Down