1a7653a · text · git.iko.soy

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Implement and test lazy scanr and reverse

1a7653aBryan O'Sullivan18 years ago

Data/Text.hs+1−1

compare with master

unifiedsplit

@@ -500,7 +500,7 @@ scanl1 f t | null t = empty

500

501-- | /O(n)/ 'scanr' is the right-to-left dual of 'scanl'.

502--

503−-- > scanr f v t == reverse (scanl (flip f) v t)

503+-- > scanr f v == reverse . scanl (flip f) v . reverse

504scanr :: (Char -> Char -> Char) -> Char -> Text -> Text

505scanr f z = S.reverse . S.reverseScanr f z . reverseStream

506{-# INLINE scanr #-}

Data/Text/Lazy.hs+14−2

@@ -58,7 +58,7 @@ module Data.Text.Lazy

58 , intercalate

59 , intersperse

60 , transpose

61− -- , reverse

61+ , reverse

63 -- * Folds

64 , foldl

@@ -81,7 +81,7 @@ module Data.Text.Lazy

81 -- ** Scans

82 , scanl

83 , scanl1

84− -- , scanr

84+ , scanr

85 -- , scanr1

87 -- ** Accumulating maps

@@ -363,6 +363,12 @@ transpose ts = L.map (\ss -> Chunk (T.pack ss) Empty)

363 (L.transpose (L.map unpack ts))

364-- TODO: make this fast

365

366+-- | /O(n)/ 'reverse' @t@ returns the elements of @t@ in reverse order.

367+reverse :: Text -> Text

368+reverse = rev Empty

369+ where rev a Empty = a

370+ rev a (Chunk t ts) = rev (Chunk (T.reverse t) a) ts

371+

366-- | /O(n)/ 'foldl', applied to a binary operator, a starting value

372-- | /O(n)/ 'foldl', applied to a binary operator, a starting value

367-- (typically the left-identity of the operator), and a 'Text',

373-- (typically the left-identity of the operator), and a 'Text',

368-- reduces the 'Text' using the binary operator, from left to right.

374-- reduces the 'Text' using the binary operator, from left to right.

@@ -466,6 +472,12 @@ scanl1 f t0 = case uncons t0 of

466 Just (t,ts) -> scanl f t ts

472 Just (t,ts) -> scanl f t ts

467{-# INLINE scanl1 #-}

473{-# INLINE scanl1 #-}

468

474

475+-- | /O(n)/ 'scanr' is the right-to-left dual of 'scanl'.

476+--

477+-- > scanr f v == reverse . scanl (flip f) v . reverse

478+scanr :: (Char -> Char -> Char) -> Char -> Text -> Text

479+scanr f v = reverse . scanl (flip f) v . reverse

480+

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

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

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

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

471-- parameter from left to right, and returns a final 'Text'.

483-- parameter from left to right, and returns a final 'Text'.

tests/Properties.hs+4

@@ -159,6 +159,7 @@ prop_TL_intersperse c = L.intersperse c `eqP` (unpackT . TL.intersperse c)

159prop_T_transpose = L.transpose `eq` (map unpackT . T.transpose . map T.pack)

160prop_TL_transpose = L.transpose `eq` (map unpackT . TL.transpose . map TL.pack)

161prop_T_reverse = L.reverse `eqP` (unpackT . T.reverse)

162+prop_TL_reverse = L.reverse `eqP` (unpackT . TL.reverse)

162prop_T_reverse_short n = L.reverse `eqP` (unpackT . S.reverse . shorten n . S.stream)

163prop_T_reverse_short n = L.reverse `eqP` (unpackT . S.reverse . shorten n . S.stream)

163

164

164prop_T_foldl f z = L.foldl f z `eqP` (T.foldl f z)

165prop_T_foldl f z = L.foldl f z `eqP` (T.foldl f z)

@@ -198,6 +199,7 @@ prop_TL_scanl f z = L.scanl f z `eqP` (unpackT . TL.scanl f z)

198prop_T_scanl1 f = L.scanl1 f `eqP` (unpackT . T.scanl1 f)

199prop_T_scanl1 f = L.scanl1 f `eqP` (unpackT . T.scanl1 f)

199prop_TL_scanl1 f = L.scanl1 f `eqP` (unpackT . TL.scanl1 f)

200prop_TL_scanl1 f = L.scanl1 f `eqP` (unpackT . TL.scanl1 f)

200prop_T_scanr f z = L.scanr f z `eqP` (unpackT . T.scanr f z)

201prop_T_scanr f z = L.scanr f z `eqP` (unpackT . T.scanr f z)

202+prop_TL_scanr f z = L.scanr f z `eqP` (unpackT . TL.scanr f z)

201prop_T_scanr1 f = L.scanr1 f `eqP` (unpackT . T.scanr1 f)

203prop_T_scanr1 f = L.scanr1 f `eqP` (unpackT . T.scanr1 f)

202

204

203prop_T_mapAccumL f z = L.mapAccumL f z `eqP` (second unpackT . T.mapAccumL f z)

205prop_T_mapAccumL f z = L.mapAccumL f z `eqP` (second unpackT . T.mapAccumL f z)

@@ -392,6 +394,7 @@ tests = [

392 ("prop_T_transpose", mytest prop_T_transpose),

394 ("prop_T_transpose", mytest prop_T_transpose),

393 ("prop_TL_transpose", mytest prop_TL_transpose),

395 ("prop_TL_transpose", mytest prop_TL_transpose),

394 ("prop_T_reverse", mytest prop_T_reverse),

396 ("prop_T_reverse", mytest prop_T_reverse),

397+ ("prop_TL_reverse", mytest prop_TL_reverse),

395 ("prop_T_reverse_short", mytest prop_T_reverse_short),

398 ("prop_T_reverse_short", mytest prop_T_reverse_short),

396

399

397 ("prop_T_foldl", mytest prop_T_foldl),

400 ("prop_T_foldl", mytest prop_T_foldl),

@@ -425,6 +428,7 @@ tests = [

425 ("prop_T_scanl1", mytest prop_T_scanl1),

428 ("prop_T_scanl1", mytest prop_T_scanl1),

426 ("prop_TL_scanl1", mytest prop_TL_scanl1),

429 ("prop_TL_scanl1", mytest prop_TL_scanl1),

427 ("prop_T_scanr", mytest prop_T_scanr),

430 ("prop_T_scanr", mytest prop_T_scanr),

431+ ("prop_TL_scanr", mytest prop_TL_scanr),

428 ("prop_T_scanr1", mytest prop_T_scanr1),

432 ("prop_T_scanr1", mytest prop_T_scanr1),

429

433

430 ("prop_T_mapAccumL", mytest prop_T_mapAccumL),

434 ("prop_T_mapAccumL", mytest prop_T_mapAccumL),