34f6990 · text · git.iko.soy

git.iko.soy/text

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Implement splitAt

34f6990Bryan O'Sullivan18 years ago

Data/Text.hs+17−1

compare with master

unifiedsplit

@@ -95,7 +95,7 @@ module Data.Text

95 , drop

96 , takeWhile

97 , dropWhile

98− -- , splitAt

98+ , splitAt

99 -- , span

100 -- , break

101 -- , group

@@ -633,6 +633,22 @@ dropWhile p (Text arr off len) = loop off 0

633 unstream (S.dropWhile p (stream t)) = dropWhile p t

634 #-}

635

636+-- | /O(n)/ 'splitAt' @n t@ returns a pair whose first element is a

637+-- prefix of @t@ of length @n@ and second element is the remainder of

638+-- the string. It is equivalent to @('take' n t, 'drop' n t)@.

639+splitAt :: Int -> Text -> (Text, Text)

640+splitAt n t@(Text arr off len)

641+ | n <= 0 = (empty, t)

642+ | n >= len = (t, empty)

643+ | otherwise = (Text arr off k, Text arr (off+k) (len-k))

644+ where k = loop off 0

645+ end = off + len

646+ loop !i !count

647+ | i >= end || count >= n = i - off

648+ | otherwise = loop (i+d) (count+1)

649+ where d = iter_ arr i

650+{-# INLINE splitAt #-}

651+

636-- | /O(n)/ Return all initial segments of the given 'Text', shortest

652-- | /O(n)/ Return all initial segments of the given 'Text', shortest

637-- first.

653-- first.

638inits :: Text -> [Text]

654inits :: Text -> [Text]

tests/Properties.hs+2

@@ -92,6 +92,7 @@ prop_takeWhile p = L.takeWhile p `eqP` (unpack . T.takeWhile p)

92prop_takeWhileS p = L.takeWhile p `eqP` (unpack . unstream . S.takeWhile p . stream)

93prop_dropWhile p = L.dropWhile p `eqP` (unpack . T.dropWhile p)

94prop_dropWhileS p = L.dropWhile p `eqP` (unpack . unstream . S.dropWhile p . stream)

95+prop_splitAt n = L.splitAt n `eqP` ((unpack *** unpack) . T.splitAt n)

95prop_inits = L.inits `eqP` (map unpack . T.inits)

96prop_inits = L.inits `eqP` (map unpack . T.inits)

96prop_tails = L.tails `eqP` (map unpack . T.tails)

97prop_tails = L.tails `eqP` (map unpack . T.tails)

@@ -179,6 +180,7 @@ tests = [

179 ("prop_takeWhileS", mytest prop_takeWhileS),

180 ("prop_takeWhileS", mytest prop_takeWhileS),

180 ("prop_dropWhile", mytest prop_dropWhile),

181 ("prop_dropWhile", mytest prop_dropWhile),

181 ("prop_dropWhileS", mytest prop_dropWhileS),

182 ("prop_dropWhileS", mytest prop_dropWhileS),

183+ ("prop_splitAt", mytest prop_splitAt),

182 ("prop_inits", mytest prop_inits),

184 ("prop_inits", mytest prop_inits),

183 ("prop_tails", mytest prop_tails),

185 ("prop_tails", mytest prop_tails),

184

186