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Optimize array indexing in delete' and deleteKeyExists #528

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Optimize array indexing in delete' and deleteKeyExists #528

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28 changes: 10 additions & 18 deletions Data/HashMap/Internal.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -1135,10 +1135,9 @@ delete' h0 k0 m0 = go h0 k0 0 m0
else case st' of
Empty | A.length ary == 1 -> Empty
| A.length ary == 2 ->
case (i, A.index ary 0, A.index ary 1) of
(0, _, l) | isLeafOrCollision l -> l
(1, l, _) | isLeafOrCollision l -> l
_ -> bIndexed
case A.index ary (1 - i) of
l | isLeafOrCollision l -> l
_ -> bIndexed
| otherwise -> bIndexed
where
bIndexed = BitmapIndexed (b .&. complement m) (A.delete ary i)
Expand All @@ -1161,11 +1160,8 @@ delete' h0 k0 m0 = go h0 k0 0 m0
go h k _ t@(Collision hy v)
| h == hy = case indexOf k v of
Just i
| A.length v == 2 ->
if i == 0
then Leaf h (A.index v 1)
else Leaf h (A.index v 0)
| otherwise -> Collision h (A.delete v i)
| A.length v == 2 -> Leaf h (A.index v (1 - i))
| otherwise -> Collision h (A.delete v i)
Nothing -> t
| otherwise = t
{-# INLINABLE delete' #-}
Expand All @@ -1186,10 +1182,9 @@ deleteKeyExists !collPos0 !h0 !k0 !m0 = go collPos0 h0 k0 m0
in case st' of
Empty | A.length ary == 1 -> Empty
| A.length ary == 2 ->
case (i, A.index ary 0, A.index ary 1) of
(0, _, l) | isLeafOrCollision l -> l
(1, l, _) | isLeafOrCollision l -> l
_ -> bIndexed
case A.index ary (1 - i) of
l | isLeafOrCollision l -> l
_ -> bIndexed
| otherwise -> bIndexed
where
bIndexed = BitmapIndexed (b .&. complement m) (A.delete ary i)
Expand All @@ -1208,11 +1203,8 @@ deleteKeyExists !collPos0 !h0 !k0 !m0 = go collPos0 h0 k0 m0
_ -> Full (A.update ary i st')
where i = index' shiftedHash
go collPos _shiftedHash _k (Collision h v)
| A.length v == 2
= if collPos == 0
then Leaf h (A.index v 1)
else Leaf h (A.index v 0)
| otherwise = Collision h (A.delete v collPos)
| A.length v == 2 = Leaf h (A.index v (1 - collPos))
| otherwise = Collision h (A.delete v collPos)
go !_ !_ !_ Empty = Empty -- error "Internal error: deleteKeyExists empty"

-- Customized version of 'index' that doesn't require a 'Shift'.
Expand Down