afba704 · text · git.iko.soy

git.iko.soy/text

Implement scanr1

--HG-- extra : convert_revision : ca8100e2e4aa76aa6c1115af58bd1e9171a392f5

commitafba704f2c1d03d67844f3e83f9dec868da26789 authorBryan O'Sullivan <bos@serpentine.com> dateSun 22 Feb 2009, 09:13 (18 years ago) parente2f1397

2 files changed+9−4

compare with master

unifiedsplit

Data/Text.hs+7−4 tests/Properties.hs+2

Data/Text.hs+7−4

@@ -77,7 +77,7 @@ module Data.Text

7777 , scanl

7878 , scanl1

7979 , scanr

80− -- , scanr1

80+ , scanr1

8181

8282 -- ** Accumulating maps

8383 , mapAccumL

@@ -520,9 +520,12 @@ scanr :: (Char -> Char -> Char) -> Char -> Text -> Text

520520scanr f z = S.reverse . S.reverseScanr f z . reverseStream

521521{-# INLINE scanr #-}

522522

523−shorten n t@(S.Stream arr off len) | n < len && n > 0 = S.Stream arr off n

524− | otherwise = t

525−info (S.Stream _ _ len) = len

523+-- | /O(n)/ 'scanr1' is a variant of 'scanr' that has no starting

524+-- value argument. This function is subject to array fusion.

525+scanr1 :: (Char -> Char -> Char) -> Text -> Text

526+scanr1 f t | null t = empty

527+ | otherwise = scanr f (last t) (init t)

528+{-# INLINE scanr1 #-}

526529

527530-- | /O(n)/ Like a combination of 'map' and 'foldl'. Applies a

528531-- function to each element of a 'Text', passing an accumulating

tests/Properties.hs+2

@@ -101,6 +101,7 @@ prop_minimum = L.minimum `eqEP` T.minimum

101101prop_scanl f z = L.scanl f z `eqP` (unpack . T.scanl f z)

102102prop_scanl1 f = L.scanl1 f `eqP` (unpack . T.scanl1 f)

103103prop_scanr f z = L.scanr f z `eqP` (unpack . T.scanr f z)

104+prop_scanr1 f = L.scanr1 f `eqP` (unpack . T.scanr1 f)

104105

105106prop_mapAccumL f z = (snd . L.mapAccumL f z)`eqP` (unpack . T.mapAccumL f z)

106107 where types = f :: Int -> Char -> (Int,Char)

@@ -240,6 +241,7 @@ tests = [

240241 ("prop_scanl", mytest prop_scanl),

241242 ("prop_scanl1", mytest prop_scanl1),

242243 ("prop_scanr", mytest prop_scanr),

244+ ("prop_scanr1", mytest prop_scanr1),

243245

244246 ("prop_mapAccumL", mytest prop_mapAccumL),

245247