d601012 · streamly · git.iko.soy

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Fix & improve doc for Parser(D).groupBy

d601012Adithya Kumar6 years ago

src/Streamly/Internal/Data/Parser.hs+21−11

compare with master

unifiedsplit

@@ -576,25 +576,35 @@ escapedFrameBy _begin _end _escape _p = undefined

576wordBy :: MonadCatch m => (a -> Bool) -> Fold m a b -> Parser m a b

577wordBy f = K.toParserK . D.wordBy f

578

579+-- | Given an input stream @[a,b,c,...]@ and a comparison function @cmp@, the

579−-- | @groupBy cmp f $ S.fromList [a,b,c,...]@ assigns the element @a@ to the

580+-- parser assigns the element @a@ to the first group, then if @a \`cmp` b@ is

580−-- first group, then if @a \`cmp` b@ is 'True' @b@ is also assigned to the same

581+-- 'True' @b@ is also assigned to the same group. If @a \`cmp` c@ is 'True'

581−-- group. If @a \`cmp` c@ is 'True' then @c@ is also assigned to the same

582+-- then @c@ is also assigned to the same group and so on. When the comparison

582−-- group and so on. When the comparison fails a new group is started. Each

583−-- group is folded using the 'Fold' @f@ and the result of the fold is emitted

583+-- fails the parser is terminated. Each group is folded using the 'Fold' @f@ and

584−-- in the output stream.

584+-- the result of the fold is the result of the parser.

585--

586-- * Stops - when the comparison fails.

587-- * Fails - never.

588--

589−-- @

589+-- > runGroupsBy eq =

590+-- > Stream.toList

590−-- S.groupsBy cmp f = S.parseMany (PR.groupBy cmp f)

591+-- > . Stream.parseMany (groupBy eq Fold.toList)

591−-- @

592+-- > . Stream.fromList

592--

593--

593−-- /Unimplemented/

594+-- >>> runGroupsBy (<) []

595+-- []

596+--

597+-- >>> runGroupsBy (<) [1]

598+-- [[1]]

599+--

600+-- >>> runGroupsBy (<) [3, 5, 4, 1, 2, 0]

601+-- [[3, 5, 4], [1, 2], [0]]

602+--

603+-- /Internal/

594--

604--

595{-# INLINABLE groupBy #-}

605{-# INLINABLE groupBy #-}

596groupBy :: MonadCatch m => (a -> a -> Bool) -> Fold m a b -> Parser m a b

606groupBy :: MonadCatch m => (a -> a -> Bool) -> Fold m a b -> Parser m a b

597−groupBy cmp = K.toParserK . D.groupBy cmp

607+groupBy eq = K.toParserK . D.groupBy eq

598

608

599-- | Unlike 'groupBy' this combinator performs a rolling comparison of two

609-- | Unlike 'groupBy' this combinator performs a rolling comparison of two

600-- successive elements in the input stream. Assuming the input stream to the

610-- successive elements in the input stream. Assuming the input stream to the

src/Streamly/Internal/Data/Parser/ParserD.hs+2−2

@@ -597,7 +597,7 @@ data GroupByState a s

597--

598{-# INLINE groupBy #-}

599groupBy :: Monad m => (a -> a -> Bool) -> Fold m a b -> Parser m a b

600−groupBy cmp (Fold fstep finitial fextract) = Parser step initial extract

600+groupBy eq (Fold fstep finitial fextract) = Parser step initial extract

601

602 where

603

@@ -618,7 +618,7 @@ groupBy cmp (Fold fstep finitial fextract) = Parser step initial extract

618

619 step (GroupByInit s) a = grouper s a a

620 step (GroupByGrouping a0 s) a =

621− if cmp a0 a

621+ if eq a0 a

622 then grouper s a0 a

623 else Done 1 <$> fextract s

624