cb8194d · text · git.iko.soy

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Implement and test lazy inits and tails

cb8194dBryan O'Sullivan18 years ago

Data/Text/Lazy.hs+18−2

compare with master

unifiedsplit

@@ -103,8 +103,8 @@ module Data.Text.Lazy

103 , break

104 , group

105 , groupBy

106− -- , inits

106+ , inits

107− -- , tails

107+ , tails

108

109 -- ** Breaking into many substrings

110 -- , split

@@ -630,6 +630,22 @@ groupBy eq (Chunk t ts) = cons x ys : groupBy eq zs

630 x = T.unsafeHead t

631 xs = chunk (T.unsafeTail t) ts

632

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

634+-- shortest first.

635+inits :: Text -> [Text]

636+inits = (Empty :) . inits'

637+ where inits' Empty = []

638+ inits' (Chunk t ts) = L.map (\t' -> Chunk t' Empty) (L.tail (T.inits t))

639+ ++ L.map (Chunk t) (inits' ts)

640+

641+-- | /O(n)/ Return all final segments of the given 'Text', longest

642+-- first.

643+tails :: Text -> [Text]

644+tails Empty = Empty : []

645+tails ts@(Chunk t ts')

646+ | T.length t == 1 = ts : tails ts'

647+ | otherwise = ts : tails (Chunk (T.unsafeTail t) ts')

648+

633revChunks :: [T.Text] -> Text

649revChunks :: [T.Text] -> Text

634revChunks = L.foldl' (flip chunk) Empty

650revChunks = L.foldl' (flip chunk) Empty

635

651

tests/Properties.hs+4

@@ -238,7 +238,9 @@ prop_TL_group = L.group `eqP` (map unpackT . TL.group)

238prop_T_groupBy p = L.groupBy p `eqP` (map unpackT . T.groupBy p)

239prop_TL_groupBy p = L.groupBy p `eqP` (map unpackT . TL.groupBy p)

240prop_T_inits = L.inits `eqP` (map unpackT . T.inits)

241+prop_TL_inits = L.inits `eqP` (map unpackT . TL.inits)

241prop_T_tails = L.tails `eqP` (map unpackT . T.tails)

242prop_T_tails = L.tails `eqP` (map unpackT . T.tails)

243+prop_TL_tails = L.tails `eqP` (map unpackT . TL.tails)

242

244

243prop_T_split_i c = id `eq` (T.intercalate (T.singleton c) . T.split c)

245prop_T_split_i c = id `eq` (T.intercalate (T.singleton c) . T.split c)

244

246

@@ -440,7 +442,9 @@ tests = [

440 ("prop_T_groupBy", mytest prop_T_groupBy),

442 ("prop_T_groupBy", mytest prop_T_groupBy),

441 ("prop_TL_groupBy", mytest prop_TL_groupBy),

443 ("prop_TL_groupBy", mytest prop_TL_groupBy),

442 ("prop_T_inits", mytest prop_T_inits),

444 ("prop_T_inits", mytest prop_T_inits),

445+ ("prop_TL_inits", mytest prop_TL_inits),

443 ("prop_T_tails", mytest prop_T_tails),

446 ("prop_T_tails", mytest prop_T_tails),

447+ ("prop_TL_tails", mytest prop_TL_tails),

444

448

445 ("prop_T_split_i", mytest prop_T_split_i),

449 ("prop_T_split_i", mytest prop_T_split_i),

446 ("prop_T_splitWith", mytest prop_T_splitWith),

450 ("prop_T_splitWith", mytest prop_T_splitWith),