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Avoid creating an out-of-bounds Char #47

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Mar 14, 2025
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Avoid creating an out-of-bounds Char #47

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20 changes: 10 additions & 10 deletions src/Regex/Internal/CharSet.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -105,8 +105,8 @@ insertRange :: (Char, Char) -> CharSet -> CharSet
insertRange (cl,ch) cs | cl > ch = cs
insertRange (cl,ch) cs = l `join` fromRange (cl,ch) `join` r
where
(l,mr) = split cl cs
(_,r) = split (unsafeChr (ord ch + 1)) mr
(l,mr) = split (ord cl) cs
(_,r) = split (ord ch + 1) mr

-- | \(O(\min(n,C))\). Delete a @Char@ from a set.
delete :: Char -> CharSet -> CharSet
Expand All @@ -117,8 +117,8 @@ deleteRange :: (Char, Char) -> CharSet -> CharSet
deleteRange (cl,ch) cs | cl > ch = cs
deleteRange (cl,ch) cs = l `join` r
where
(l,mr) = split cl cs
(_,r) = split (unsafeChr (ord ch + 1)) mr
(l,mr) = split (ord cl) cs
(_,r) = split (ord ch + 1) mr

-- | \(O(s \min(s,C))\). Map a function over all @Char@s in a set.
map :: (Char -> Char) -> CharSet -> CharSet
Expand Down Expand Up @@ -169,14 +169,14 @@ ranges cs = [(unsafeChr cl, ch) | (cl,ch) <- IM.assocs (unCharSet cs)]
--------------------

-- | \(O(\min(n,W))\). Split a set into one containing @Char@s smaller than
-- the given @Char@ and one greater than or equal to the given @Char@.
split :: Char -> CharSet -> (CharSet, CharSet)
split !c cs = case IM.splitLookup (ord c) (unCharSet cs) of
(l, Just ch, r) -> (CharSet l, CharSet $ IM.insert (ord c) ch r)
-- the given char and one greater than or equal to the given char.
split :: Int -> CharSet -> (CharSet, CharSet)
split !c cs = case IM.splitLookup c (unCharSet cs) of
(l, Just ch, r) -> (CharSet l, CharSet $ IM.insert c ch r)
(l, Nothing, r) -> case IM.maxViewWithKey l of
Just ((lgl,lgh),l1)
| lgh >= c -> ( CharSet $ IM.insert lgl (unsafeChr (ord c - 1)) l1
, CharSet $ IM.insert (ord c) lgh r )
| ord lgh >= c -> ( CharSet $ IM.insert lgl (unsafeChr (c - 1)) l1
, CharSet $ IM.insert c lgh r )
_ -> (CharSet l, CharSet r)
-- The bang on c helps because splitLookup was unfortunately not strict in
-- the lookup key until https://github.com/haskell/containers/pull/982.
Expand Down