-{-# LANGUAGE RankNTypes, TypeFamilies, BangPatterns, Trustworthy #-}
+{-# LANGUAGE RankNTypes, TypeFamilies, BangPatterns, Safe#-}
+{-| The module @Pipes.Text@ closely follows @Pipes.ByteString@ from
+ the @pipes-bytestring@ package. A draft tutorial can be found in
+ @Pipes.Text.Tutorial@.
+-}
module Pipes.Text (
- -- * Effectful Text
- -- $intro
-
- -- * Lenses
- -- $lenses
-
- -- ** @view@ \/ @(^.)@
- -- $view
-
- -- ** @over@ \/ @(%~)@
- -- $over
-
- -- ** @zoom@
- -- $zoom
-
- -- * Special types: @Producer Text m (Producer Text m r)@ and @FreeT (Producer Text m) m r@
- -- $special
-
-- * Producers
fromLazy
, map
, concatMap
, take
- , drop
, takeWhile
- , dropWhile
, filter
- , scan
- , pack
- , unpack
, toCaseFold
, toLower
, toUpper
, stripStart
+ , scan
-- * Folds
, toLazy
, minimum
, find
, index
- , count
-- * Primitive Character Parsers
, nextChar
, peekChar
, isEndOfChars
- -- * Parsing Lenses
+ -- * Parsing Lenses
, splitAt
, span
, break
, word
, line
- -- * FreeT Splitters
+ -- * Transforming Text and Character Streams
+ , drop
+ , dropWhile
+ , pack
+ , unpack
+ , intersperse
+
+ -- * FreeT Transformations
, chunksOf
, splitsWith
, splits
, groupsBy
, groups
, lines
- , words
-
- -- * Transformations
- , intersperse
- , packChars
-
- -- * Joiners
- , intercalate
, unlines
+ , words
, unwords
+ , intercalate
-- * Re-exports
-- $reexports
, module Data.ByteString
, module Data.Text
- , module Data.Profunctor
, module Pipes.Parse
, module Pipes.Group
) where
-import Control.Applicative ((<*))
import Control.Monad (liftM, join)
-import Control.Monad.Trans.State.Strict (StateT(..), modify)
+import Control.Monad.Trans.State.Strict (modify)
import qualified Data.Text as T
import Data.Text (Text)
import qualified Data.Text.Lazy as TL
import Data.ByteString (ByteString)
import Data.Functor.Constant (Constant(Constant, getConstant))
import Data.Functor.Identity (Identity)
-import Data.Profunctor (Profunctor)
-import qualified Data.Profunctor
+
import Pipes
-import Pipes.Group (concats, intercalates, FreeT(..), FreeF(..))
+import Pipes.Group (folds, maps, concats, intercalates, FreeT(..), FreeF(..))
import qualified Pipes.Group as PG
import qualified Pipes.Parse as PP
import Pipes.Parse (Parser)
-import Pipes.Text.Encoding (Lens'_, Iso'_)
import qualified Pipes.Prelude as P
import Data.Char (isSpace)
-import Data.Word (Word8)
import Foreign.Storable (sizeOf)
import Data.Bits (shiftL)
import Prelude hiding (
words,
writeFile )
-{- $intro
- This package provides @pipes@ utilities for /text streams/ or /character streams/,
- realized as streams of 'Text' chunks. The individual chunks are uniformly /strict/,
- and thus you will generally want @Data.Text@ in scope. But the type
- @Producer Text m r@ ,as we are using it, is a sort of /pipes/ equivalent of the lazy @Text@ type.
-
- This particular module provides many functions equivalent in one way or another to
- the pure functions in
- <https://hackage.haskell.org/package/text-1.1.0.0/docs/Data-Text-Lazy.html Data.Text.Lazy>.
- They transform, divide, group and fold text streams. Though @Producer Text m r@
- is the type of \'effectful Text\', the functions in this module are \'pure\'
- in the sense that they are uniformly monad-independent.
- Simple /IO/ operations are defined in @Pipes.Text.IO@ -- as lazy IO @Text@
- operations are in @Data.Text.Lazy.IO@. Inter-operation with @ByteString@
- is provided in @Pipes.Text.Encoding@, which parallels @Data.Text.Lazy.Encoding@.
-
- The Text type exported by @Data.Text.Lazy@ is basically that of a lazy list of
- strict Text: the implementation is arranged so that the individual strict 'Text'
- chunks are kept to a reasonable size; the user is not aware of the divisions
- between the connected 'Text' chunks.
- So also here: the functions in this module are designed to operate on streams that
- are insensitive to text boundaries. This means that they may freely split
- text into smaller texts and /discard empty texts/. The objective, though, is
- that they should /never concatenate texts/ in order to provide strict upper
- bounds on memory usage.
-
- For example, to stream only the first three lines of 'stdin' to 'stdout' you
- might write:
-
-> import Pipes
-> import qualified Pipes.Text as Text
-> import qualified Pipes.Text.IO as Text
-> import Pipes.Group (takes')
-> import Lens.Family
->
-> main = runEffect $ takeLines 3 Text.stdin >-> Text.stdout
-> where
-> takeLines n = Text.unlines . takes' n . view Text.lines
-
- The above program will never bring more than one chunk of text (~ 32 KB) into
- memory, no matter how long the lines are.
-
--}
-{- $lenses
- As this example shows, one superficial difference from @Data.Text.Lazy@
- is that many of the operations, like 'lines', are \'lensified\'; this has a
- number of advantages (where it is possible); in particular it facilitates their
- use with 'Parser's of Text (in the general <http://hackage.haskell.org/package/pipes-parse-3.0.1/docs/Pipes-Parse-Tutorial.html pipes-parse>
- sense.) The disadvantage, famously, is that the messages you get for type errors can be
- a little alarming. The remarks that follow in this section are for non-lens adepts.
-
- Each lens exported here, e.g. 'lines', 'chunksOf' or 'splitAt', reduces to the
- intuitively corresponding function when used with @view@ or @(^.)@. Instead of
- writing:
-
- > splitAt 17 producer
-
- as we would with the Prelude or Text functions, we write
-
- > view (splitAt 17) producer
-
- or equivalently
-
- > producer ^. splitAt 17
-
- This may seem a little indirect, but note that many equivalents of
- @Text -> Text@ functions are exported here as 'Pipe's. Here too we recover the intuitively
- corresponding functions by prefixing them with @(>->)@. Thus something like
-
-> stripLines = Text.unlines . Group.maps (>-> Text.stripStart) . view Text.lines
-
- would drop the leading white space from each line.
-
- The lenses in this library are marked as /improper/; this just means that
- they don't admit all the operations of an ideal lens, but only /getting/ and /focusing/.
- Just for this reason, though, the magnificent complexities of the lens libraries
- are a distraction. The lens combinators to keep in mind, the ones that make sense for
- our lenses, are @view@ \/ @(^.)@), @over@ \/ @(%~)@ , and @zoom@.
-
- One need only keep in mind that if @l@ is a @Lens'_ a b@, then:
-
--}
-{- $view
- @view l@ is a function @a -> b@ . Thus @view l a@ (also written @a ^. l@ )
- is the corresponding @b@; as was said above, this function will be exactly the
- function you think it is, given its name. Thus to uppercase the first n characters
- of a Producer, leaving the rest the same, we could write:
-
-
- > upper n p = do p' <- p ^. Text.splitAt n >-> Text.toUpper
- > p'
--}
-{- $over
- @over l@ is a function @(b -> b) -> a -> a@. Thus, given a function that modifies
- @b@s, the lens lets us modify an @a@ by applying @f :: b -> b@ to
- the @b@ that we can \"see\" through the lens. So @over l f :: a -> a@
- (it can also be written @l %~ f@).
- For any particular @a@, then, @over l f a@ or @(l %~ f) a@ is a revised @a@.
- So above we might have written things like these:
-
- > stripLines = Text.lines %~ maps (>-> Text.stripStart)
- > stripLines = over Text.lines (maps (>-> Text.stripStart))
- > upper n = Text.splitAt n %~ (>-> Text.toUpper)
-
--}
-{- $zoom
- @zoom l@, finally, is a function from a @Parser b m r@
- to a @Parser a m r@ (or more generally a @StateT (Producer b m x) m r@).
- Its use is easiest to see with an decoding lens like 'utf8', which
- \"sees\" a Text producer hidden inside a ByteString producer:
- @drawChar@ is a Text parser, returning a @Maybe Char@, @zoom utf8 drawChar@ is
- a /ByteString/ parser, returning a @Maybe Char@. @drawAll@ is a Parser that returns
- a list of everything produced from a Producer, leaving only the return value; it would
- usually be unreasonable to use it. But @zoom (splitAt 17) drawAll@
- returns a list of Text chunks containing the first seventeen Chars, and returns the rest of
- the Text Producer for further parsing. Suppose that we want, inexplicably, to
- modify the casing of a Text Producer according to any instruction it might
- contain at the start. Then we might write something like this:
-
-> obey :: Monad m => Producer Text m b -> Producer Text m b
-> obey p = do (ts, p') <- lift $ runStateT (zoom (Text.splitAt 7) drawAll) p
-> let seven = T.concat ts
-> case T.toUpper seven of
-> "TOUPPER" -> p' >-> Text.toUpper
-> "TOLOWER" -> p' >-> Text.toLower
-> _ -> do yield seven
-> p'
-
-
-> >>> let doc = each ["toU","pperTh","is document.\n"]
-> >>> runEffect $ obey doc >-> Text.stdout
-> THIS DOCUMENT.
-
- The purpose of exporting lenses is the mental economy achieved with this three-way
- applicability. That one expression, e.g. @lines@ or @splitAt 17@ can have these
- three uses is no more surprising than that a pipe can act as a function modifying
- the output of a producer, namely by using @>->@ to its left: @producer >-> pipe@
- -- but can /also/ modify the inputs to a consumer by using @>->@ to its right:
- @pipe >-> consumer@
-
- The three functions, @view@ \/ @(^.)@, @over@ \/ @(%~)@ and @zoom@ are supplied by
- both <http://hackage.haskell.org/package/lens lens> and
- <http://hackage.haskell.org/package/lens-family lens-family> The use of 'zoom' is explained
- in <http://hackage.haskell.org/package/pipes-parse-3.0.1/docs/Pipes-Parse-Tutorial.html Pipes.Parse.Tutorial>
- and to some extent in the @Pipes.Text.Encoding@ module here.
+-- $setup
+-- >>> :set -XOverloadedStrings
+-- >>> import Data.Text (Text)
+-- >>> import qualified Data.Text as T
+-- >>> import qualified Data.Text.Lazy.IO as TL
+-- >>> import Data.Char
--}
-{- $special
- These simple 'lines' examples reveal a more important difference from @Data.Text.Lazy@ .
- This is in the types that are most closely associated with our central text type,
- @Producer Text m r@. In @Data.Text@ and @Data.Text.Lazy@ we find functions like
-
-> splitAt :: Int -> Text -> (Text, Text)
-> lines :: Text -> [Text]
-> chunksOf :: Int -> Text -> [Text]
-
- which relate a Text with a pair of Texts or a list of Texts.
- The corresponding functions here (taking account of \'lensification\') are
-
-> view . splitAt :: (Monad m, Integral n) => n -> Producer Text m r -> Producer Text m (Producer Text m r)
-> view lines :: Monad m => Producer Text m r -> FreeT (Producer Text m) m r
-> view . chunksOf :: (Monad m, Integral n) => n -> Producer Text m r -> FreeT (Producer Text m) m r
-
- Some of the types may be more readable if you imagine that we have introduced
- our own type synonyms
-
-> type Text m r = Producer T.Text m r
-> type Texts m r = FreeT (Producer T.Text m) m r
-
- Then we would think of the types above as
-
-> view . splitAt :: (Monad m, Integral n) => n -> Text m r -> Text m (Text m r)
-> view lines :: (Monad m) => Text m r -> Texts m r
-> view . chunksOf :: (Monad m, Integral n) => n -> Text m r -> Texts m r
-
- which brings one closer to the types of the similar functions in @Data.Text.Lazy@
-
- In the type @Producer Text m (Producer Text m r)@ the second
- element of the \'pair\' of effectful Texts cannot simply be retrieved
- with something like 'snd'. This is an \'effectful\' pair, and one must work
- through the effects of the first element to arrive at the second Text stream, even
- if you are proposing to throw the Text in the first element away.
- Note that we use Control.Monad.join to fuse the pair back together, since it specializes to
-
-> join :: Monad m => Producer Text m (Producer m r) -> Producer m r
-
- The return type of 'lines', 'words', 'chunksOf' and the other /splitter/ functions,
- @FreeT (Producer m Text) m r@ -- our @Texts m r@ -- is the type of (effectful)
- lists of (effectful) texts. The type @([Text],r)@ might be seen to gather
- together things of the forms:
-
-> r
-> (Text,r)
-> (Text, (Text, r))
-> (Text, (Text, (Text, r)))
-> (Text, (Text, (Text, (Text, r))))
-> ...
-
- (We might also have identified the sum of those types with @Free ((,) Text) r@
- -- or, more absurdly, @FreeT ((,) Text) Identity r@.)
-
- Similarly, our type @Texts m r@, or @FreeT (Text m) m r@ -- in fact called
- @FreeT (Producer Text m) m r@ here -- encompasses all the members of the sequence:
-
-> m r
-> Text m r
-> Text m (Text m r)
-> Text m (Text m (Text m r))
-> Text m (Text m (Text m (Text m r)))
-> ...
-
- We might have used a more specialized type in place of @FreeT (Producer a m) m r@,
- or indeed of @FreeT (Producer Text m) m r@, but it is clear that the correct
- result type of 'lines' will be isomorphic to @FreeT (Producer Text m) m r@ .
-
- One might think that
-
-> lines :: Monad m => Lens'_ (Producer Text m r) (FreeT (Producer Text m) m r)
-> view . lines :: Monad m => Producer Text m r -> FreeT (Producer Text m) m r
-
- should really have the type
-
-> lines :: Monad m => Pipe Text Text m r
-
- as e.g. 'toUpper' does. But this would spoil the control we are
- attempting to maintain over the size of chunks. It is in fact just
- as unreasonable to want such a pipe as to want
-
-> Data.Text.Lazy.lines :: Text -> Text
-
- to 'rechunk' the strict Text chunks inside the lazy Text to respect
- line boundaries. In fact we have
-
-> Data.Text.Lazy.lines :: Text -> [Text]
-> Prelude.lines :: String -> [String]
-
- where the elements of the list are themselves lazy Texts or Strings; the use
- of @FreeT (Producer Text m) m r@ is simply the 'effectful' version of this.
-
- The @Pipes.Group@ module, which can generally be imported without qualification,
- provides many functions for working with things of type @FreeT (Producer a m) m r@.
- In particular it conveniently exports the constructors for @FreeT@ and the associated
- @FreeF@ type -- a fancy form of @Either@, namely
-
-> data FreeF f a b = Pure a | Free (f b)
-
- for pattern-matching. Consider the implementation of the 'words' function, or
- of the part of the lens that takes us to the words; it is compact but exhibits many
- of the points under discussion, including explicit handling of the @FreeT@ and @FreeF@
- constuctors. Keep in mind that
-
-> newtype FreeT f m a = FreeT (m (FreeF f a (FreeT f m a)))
-> next :: Monad m => Producer a m r -> m (Either r (a, Producer a m r))
-
- Thus the @do@ block after the @FreeT@ constructor is in the base monad, e.g. 'IO' or 'Identity';
- the later subordinate block, opened by the @Free@ constructor, is in the @Producer@ monad:
-
-> words :: Monad m => Producer Text m r -> FreeT (Producer Text m) m r
-> words p = FreeT $ do -- With 'next' we will inspect p's first chunk, excluding spaces;
-> x <- next (p >-> dropWhile isSpace) -- note that 'dropWhile isSpace' is a pipe, and is thus *applied* with '>->'.
-> return $ case x of -- We use 'return' and so need something of type 'FreeF (Text m) r (Texts m r)'
-> Left r -> Pure r -- 'Left' means we got no Text chunk, but only the return value; so we are done.
-> Right (txt, p') -> Free $ do -- If we get a chunk and the rest of the producer, p', we enter the 'Producer' monad
-> p'' <- view (break isSpace) -- When we apply 'break isSpace', we get a Producer that returns a Producer;
-> (yield txt >> p') -- so here we yield everything up to the next space, and get the rest back.
-> return (words p'') -- We then carry on with the rest, which is likely to begin with space.
-
--}
-
-type Lens s t a b = forall f . Functor f => (a -> f b) -> (s -> f t)
-
-
-(^.) :: a -> ((b -> Constant b b) -> (a -> Constant b a)) -> b
-a ^. lens = getConstant (lens Constant a)
-
--- | Convert a lazy 'TL.Text' into a 'Producer' of strict 'Text's
+-- | Convert a lazy 'TL.Text' into a 'Producer' of strict 'Text's. Producers in
+-- IO can be found in 'Pipes.Text.IO' or in pipes-bytestring, employed with the
+-- decoding lenses in 'Pipes.Text.Encoding'
fromLazy :: (Monad m) => TL.Text -> Producer' Text m ()
-fromLazy = TL.foldrChunks (\e a -> yield e >> a) (return ())
+fromLazy = TL.foldrChunks (\e a -> yield e >> a) (return ())
{-# INLINE fromLazy #-}
-
+(^.) :: a -> ((b -> Constant b b) -> (a -> Constant b a)) -> b
+a ^. lens = getConstant (lens Constant a)
-- | Apply a transformation to each 'Char' in the stream
+
+-- >>> let margaret = ["Margaret, are you grieving\nOver Golde","ngrove unleaving?":: Text]
+-- >>> TL.putStrLn . toLazy $ each margaret >-> map Data.Char.toUpper
+-- MARGARET, ARE YOU GRIEVING
+-- OVER GOLDENGROVE UNLEAVING?
map :: (Monad m) => (Char -> Char) -> Pipe Text Text m r
map f = P.map (T.map f)
{-# INLINABLE map #-}
-{-# RULES "p >-> map f" forall p f .
- p >-> map f = for p (\txt -> yield (T.map f txt))
- #-}
-
-- | Map a function over the characters of a text stream and concatenate the results
+
concatMap
:: (Monad m) => (Char -> Text) -> Pipe Text Text m r
concatMap f = P.map (T.concatMap f)
{-# INLINABLE concatMap #-}
-{-# RULES "p >-> concatMap f" forall p f .
- p >-> concatMap f = for p (\txt -> yield (T.concatMap f txt))
- #-}
-
-
--- | Transform a Pipe of 'String's into one of 'Text' chunks
-pack :: Monad m => Pipe String Text m r
-pack = P.map T.pack
-{-# INLINEABLE pack #-}
-
-{-# RULES "p >-> pack" forall p .
- p >-> pack = for p (\txt -> yield (T.pack txt))
- #-}
-
--- | Transform a Pipes of 'Text' chunks into one of 'String's
-unpack :: Monad m => Pipe Text String m r
-unpack = for cat (\t -> yield (T.unpack t))
-{-# INLINEABLE unpack #-}
-
-{-# RULES "p >-> unpack" forall p .
- p >-> unpack = for p (\txt -> yield (T.unpack txt))
- #-}
-
--- | @toCaseFold@, @toLower@, @toUpper@ and @stripStart@ are standard 'Text' utilities,
--- here acting as 'Text' pipes, rather as they would on a lazy text
-toCaseFold :: Monad m => Pipe Text Text m r
-toCaseFold = P.map T.toCaseFold
-{-# INLINEABLE toCaseFold #-}
-
-{-# RULES "p >-> toCaseFold" forall p .
- p >-> toCaseFold = for p (\txt -> yield (T.toCaseFold txt))
- #-}
-
-
--- | lowercase incoming 'Text'
-toLower :: Monad m => Pipe Text Text m r
-toLower = P.map T.toLower
-{-# INLINEABLE toLower #-}
-
-{-# RULES "p >-> toLower" forall p .
- p >-> toLower = for p (\txt -> yield (T.toLower txt))
- #-}
-
--- | uppercase incoming 'Text'
-toUpper :: Monad m => Pipe Text Text m r
-toUpper = P.map T.toUpper
-{-# INLINEABLE toUpper #-}
-
-{-# RULES "p >-> toUpper" forall p .
- p >-> toUpper = for p (\txt -> yield (T.toUpper txt))
- #-}
-
--- | Remove leading white space from an incoming succession of 'Text's
-stripStart :: Monad m => Pipe Text Text m r
-stripStart = do
- chunk <- await
- let text = T.stripStart chunk
- if T.null text
- then stripStart
- else do yield text
- cat
-{-# INLINEABLE stripStart #-}
-
--- | @(take n)@ only allows @n@ individual characters to pass;
+-- | @(take n)@ only allows @n@ individual characters to pass;
-- contrast @Pipes.Prelude.take@ which would let @n@ chunks pass.
take :: (Monad m, Integral a) => a -> Pipe Text Text m ()
take n0 = go n0 where
go n
| n <= 0 = return ()
- | otherwise = do
+ | otherwise = do
txt <- await
let len = fromIntegral (T.length txt)
if (len > n)
go (n - len)
{-# INLINABLE take #-}
--- | @(drop n)@ drops the first @n@ characters
-drop :: (Monad m, Integral a) => a -> Pipe Text Text m r
-drop n0 = go n0 where
- go n
- | n <= 0 = cat
- | otherwise = do
- txt <- await
- let len = fromIntegral (T.length txt)
- if (len >= n)
- then do
- yield (T.drop (fromIntegral n) txt)
- cat
- else go (n - len)
-{-# INLINABLE drop #-}
-
-- | Take characters until they fail the predicate
takeWhile :: (Monad m) => (Char -> Bool) -> Pipe Text Text m ()
takeWhile predicate = go
else yield prefix
{-# INLINABLE takeWhile #-}
--- | Drop characters until they fail the predicate
-dropWhile :: (Monad m) => (Char -> Bool) -> Pipe Text Text m r
-dropWhile predicate = go where
- go = do
- txt <- await
- case T.findIndex (not . predicate) txt of
- Nothing -> go
- Just i -> do
- yield (T.drop i txt)
- cat
-{-# INLINABLE dropWhile #-}
-
-- | Only allows 'Char's to pass if they satisfy the predicate
filter :: (Monad m) => (Char -> Bool) -> Pipe Text Text m r
filter predicate = P.map (T.filter predicate)
{-# INLINABLE filter #-}
-{-# RULES "p >-> filter q" forall p q .
- p >-> filter q = for p (\txt -> yield (T.filter q txt))
- #-}
-
-- | Strict left scan over the characters
+-- >>> let margaret = ["Margaret, are you grieving\nOver Golde","ngrove unleaving?":: Text]
+-- >>> let title_caser a x = case a of ' ' -> Data.Char.toUpper x; _ -> x
+-- >>> toLazy $ each margaret >-> scan title_caser ' '
+-- " Margaret, Are You Grieving\nOver Goldengrove Unleaving?"
+
scan
:: (Monad m)
=> (Char -> Char -> Char) -> Char -> Pipe Text Text m r
go c'
{-# INLINABLE scan #-}
+-- | @toCaseFold@, @toLower@, @toUpper@ and @stripStart@ are standard 'Text' utilities,
+-- here acting as 'Text' pipes, rather as they would on a lazy text
+toCaseFold :: Monad m => Pipe Text Text m r
+toCaseFold = P.map T.toCaseFold
+{-# INLINEABLE toCaseFold #-}
+
+-- | lowercase incoming 'Text'
+toLower :: Monad m => Pipe Text Text m r
+toLower = P.map T.toLower
+{-# INLINEABLE toLower #-}
+
+-- | uppercase incoming 'Text'
+toUpper :: Monad m => Pipe Text Text m r
+toUpper = P.map T.toUpper
+{-# INLINEABLE toUpper #-}
+
+-- | Remove leading white space from an incoming succession of 'Text's
+stripStart :: Monad m => Pipe Text Text m r
+stripStart = do
+ chunk <- await
+ let text = T.stripStart chunk
+ if T.null text
+ then stripStart
+ else do yield text
+ cat
+{-# INLINEABLE stripStart #-}
+
{-| Fold a pure 'Producer' of strict 'Text's into a lazy
'TL.Text'
-}
foldChars step begin done = P.fold (T.foldl' step) begin done
{-# INLINABLE foldChars #-}
+
-- | Retrieve the first 'Char'
head :: (Monad m) => Producer Text m () -> m (Maybe Char)
head = go
index
:: (Monad m, Integral a)
=> a-> Producer Text m () -> m (Maybe Char)
-index n p = head (p >-> drop n)
+index n p = head (drop n p)
{-# INLINABLE index #-}
--- | Store a tally of how many segments match the given 'Text'
-count :: (Monad m, Num n) => Text -> Producer Text m () -> m n
-count c p = P.fold (+) 0 id (p >-> P.map (fromIntegral . T.count c))
-{-# INLINABLE count #-}
-
-- | Consume the first character from a stream of 'Text'
---
+--
-- 'next' either fails with a 'Left' if the 'Producer' has no more characters or
-- succeeds with a 'Right' providing the next character and the remainder of the
-- 'Producer'.
Just _-> False )
{-# INLINABLE isEndOfChars #-}
-
-- | Splits a 'Producer' after the given number of characters
splitAt
:: (Monad m, Integral n)
=> n
- -> Lens (Producer Text m x)
- (Producer Text m y)
- (Producer Text m (Producer Text m x))
- (Producer Text m (Producer Text m y))
+ -> Lens' (Producer Text m r)
+ (Producer Text m (Producer Text m r))
splitAt n0 k p0 = fmap join (k (go n0 p0))
where
go 0 p = return p
span
:: (Monad m)
=> (Char -> Bool)
- -> Lens (Producer Text m x)
- (Producer Text m y)
- (Producer Text m (Producer Text m x))
- (Producer Text m (Producer Text m y))
+ -> Lens' (Producer Text m r)
+ (Producer Text m (Producer Text m r))
span predicate k p0 = fmap join (k (go p0))
where
go p = do
break
:: (Monad m)
=> (Char -> Bool)
- -> Lens (Producer Text m x)
- (Producer Text m y)
- (Producer Text m (Producer Text m x))
- (Producer Text m (Producer Text m y))
+ -> Lens' (Producer Text m r)
+ (Producer Text m (Producer Text m r))
break predicate = span (not . predicate)
{-# INLINABLE break #-}
groupBy
:: (Monad m)
=> (Char -> Char -> Bool)
- -> Lens (Producer Text m x)
- (Producer Text m y)
- (Producer Text m (Producer Text m x))
- (Producer Text m (Producer Text m y))
+ -> Lens' (Producer Text m r)
+ (Producer Text m (Producer Text m r))
groupBy equals k p0 = fmap join (k ((go p0))) where
go p = do
x <- lift (next p)
Left r -> return (return r)
Right (txt, p') -> case T.uncons txt of
Nothing -> go p'
- Just (c, _) -> (yield txt >> p') ^. span (equals c)
+ Just (c, _) -> (yield txt >> p') ^. span (equals c)
{-# INLINABLE groupBy #-}
-- | Improper lens that splits after the first succession of identical 'Char' s
-group :: Monad m
- => Lens'_ (Producer Text m r)
+group :: Monad m
+ => Lens' (Producer Text m r)
(Producer Text m (Producer Text m r))
group = groupBy (==)
{-# INLINABLE group #-}
{-| Improper lens that splits a 'Producer' after the first word
- Unlike 'words', this does not drop leading whitespace
+ Unlike 'words', this does not drop leading whitespace
-}
-word :: (Monad m)
- => Lens (Producer Text m x)
- (Producer Text m y)
- (Producer Text m (Producer Text m x))
- (Producer Text m (Producer Text m y))
+word :: (Monad m)
+ => Lens' (Producer Text m r)
+ (Producer Text m (Producer Text m r))
word k p0 = fmap join (k (to p0))
where
to p = do
p'^.break isSpace
{-# INLINABLE word #-}
-
-line :: (Monad m)
- => Lens (Producer Text m x)
- (Producer Text m y)
- (Producer Text m (Producer Text m x))
- (Producer Text m (Producer Text m y))
+line :: (Monad m)
+ => Lens' (Producer Text m r)
+ (Producer Text m (Producer Text m r))
line = break (== '\n')
-
{-# INLINABLE line #-}
+-- | @(drop n)@ drops the first @n@ characters
+drop :: (Monad m, Integral n)
+ => n -> Producer Text m r -> Producer Text m r
+drop n p = do
+ p' <- lift $ runEffect (for (p ^. splitAt n) discard)
+ p'
+{-# INLINABLE drop #-}
+
+-- | Drop characters until they fail the predicate
+dropWhile :: (Monad m)
+ => (Char -> Bool) -> Producer Text m r -> Producer Text m r
+dropWhile predicate p = do
+ p' <- lift $ runEffect (for (p ^. span predicate) discard)
+ p'
+{-# INLINABLE dropWhile #-}
-- | Intersperse a 'Char' in between the characters of stream of 'Text'
intersperse
{-# INLINABLE intersperse #-}
+-- | Improper lens from unpacked 'Word8's to packaged 'ByteString's
+pack :: Monad m => Lens' (Producer Char m r) (Producer Text m r)
+pack k p = fmap _unpack (k (_pack p))
+{-# INLINABLE pack #-}
--- | Improper isomorphism between a 'Producer' of 'ByteString's and 'Word8's
-packChars :: Monad m => Iso'_ (Producer Char m x) (Producer Text m x)
-packChars = Data.Profunctor.dimap to (fmap from)
- where
- -- to :: Monad m => Producer Char m x -> Producer Text m x
- to p = PG.folds step id done (p^.PG.chunksOf defaultChunkSize)
+-- | Improper lens from packed 'ByteString's to unpacked 'Word8's
+unpack :: Monad m => Lens' (Producer Text m r) (Producer Char m r)
+unpack k p = fmap _pack (k (_unpack p))
+{-# INLINABLE unpack #-}
- step diffAs c = diffAs . (c:)
+_pack :: Monad m => Producer Char m r -> Producer Text m r
+_pack p = folds step id done (p^.PG.chunksOf defaultChunkSize)
+ where
+ step diffAs w8 = diffAs . (w8:)
done diffAs = T.pack (diffAs [])
+{-# INLINABLE _pack #-}
- -- from :: Monad m => Producer Text m x -> Producer Char m x
- from p = for p (each . T.unpack)
-
-{-# INLINABLE packChars #-}
+_unpack :: Monad m => Producer Text m r -> Producer Char m r
+_unpack p = for p (each . T.unpack)
+{-# INLINABLE _unpack #-}
defaultChunkSize :: Int
defaultChunkSize = 16384 - (sizeOf (undefined :: Int) `shiftL` 1)
+
-- | Split a text stream into 'FreeT'-delimited text streams of fixed size
chunksOf
:: (Monad m, Integral n)
- => n -> Lens (Producer Text m x)
- (Producer Text m y)
- (FreeT (Producer Text m) m x)
- (FreeT (Producer Text m) m y)
+ => n -> Lens' (Producer Text m r)
+ (FreeT (Producer Text m) m r)
chunksOf n k p0 = fmap concats (k (FreeT (go p0)))
where
go p = do
return $ case x of
Left r -> Pure r
Right (txt, p') -> Free $ do
- p'' <- (yield txt >> p') ^. splitAt n
+ p'' <- (yield txt >> p') ^. splitAt n
return $ FreeT (go p'')
{-# INLINABLE chunksOf #-}
splitsWith
:: (Monad m)
=> (Char -> Bool)
- -> Producer Text m r
- -> FreeT (Producer Text m) m r
+ -> Producer Text m r -> FreeT (Producer Text m) m r
splitsWith predicate p0 = FreeT (go0 p0)
where
go0 p = do
return $ case x of
Left r -> Pure r
Right (_, p') -> Free $ do
- p'' <- p' ^. span (not . predicate)
+ p'' <- p' ^. span (not . predicate)
return $ FreeT (go1 p'')
{-# INLINABLE splitsWith #-}
-- | Split a text stream using the given 'Char' as the delimiter
splits :: (Monad m)
- => Char -> Lens (Producer Text m x)
- (Producer Text m y)
- (FreeT (Producer Text m) m x)
- (FreeT (Producer Text m) m y)
+ => Char
+ -> Lens' (Producer Text m r)
+ (FreeT (Producer Text m) m r)
splits c k p =
- fmap (PG.intercalates (yield (T.singleton c))) (k (splitsWith (c ==) p))
+ fmap (intercalates (yield (T.singleton c))) (k (splitsWith (c ==) p))
{-# INLINABLE splits #-}
{-| Isomorphism between a stream of 'Text' and groups of equivalent 'Char's , using the
groupsBy
:: Monad m
=> (Char -> Char -> Bool)
- -> Lens (Producer Text m x)
- (Producer Text m y)
- (FreeT (Producer Text m) m x)
- (FreeT (Producer Text m) m y)
-groupsBy equals k p0 = fmap concats (k (FreeT (go p0))) where
+ -> Lens' (Producer Text m x) (FreeT (Producer Text m) m x)
+groupsBy equals k p0 = fmap concats (k (FreeT (go p0))) where
go p = do x <- next p
case x of Left r -> return (Pure r)
Right (bs, p') -> case T.uncons bs of
-- | Like 'groupsBy', where the equality predicate is ('==')
groups
:: Monad m
- => Lens (Producer Text m x)
- (Producer Text m y)
- (FreeT (Producer Text m) m x)
- (FreeT (Producer Text m) m y)
+ => Lens' (Producer Text m x) (FreeT (Producer Text m) m x)
groups = groupsBy (==)
{-# INLINABLE groups #-}
{-| Split a text stream into 'FreeT'-delimited lines
-}
lines
- :: (Monad m)
- => Lens (Producer Text m x)
- (Producer Text m y)
- (FreeT (Producer Text m) m x)
- (FreeT (Producer Text m) m y)
+ :: (Monad m) => Lens' (Producer Text m r) (FreeT (Producer Text m) m r)
lines k p = fmap _unlines (k (_lines p))
{-# INLINABLE lines #-}
-_lines
+unlines
:: Monad m
- => Producer Text m x -> FreeT (Producer Text m) m x
-_lines p0 = FreeT (go0 p0)
+ => Lens' (FreeT (Producer Text m) m r) (Producer Text m r)
+unlines k p = fmap _lines (k (_unlines p))
+{-# INLINABLE unlines #-}
+
+_lines :: Monad m
+ => Producer Text m r -> FreeT (Producer Text m) m r
+_lines p0 = FreeT (go0 p0)
where
go0 p = do
x <- next p
Right (_, p'') -> go0 p''
{-# INLINABLE _lines #-}
-_unlines
- :: Monad m
- => FreeT (Producer Text m) m x -> Producer Text m x
-_unlines = concats . PG.maps (<* yield (T.singleton '\n'))
+_unlines :: Monad m
+ => FreeT (Producer Text m) m r -> Producer Text m r
+_unlines = concats . maps (<* yield (T.singleton '\n'))
{-# INLINABLE _unlines #-}
+-- | Split a text stream into 'FreeT'-delimited words. Note that
+-- roundtripping with e.g. @over words id@ eliminates extra space
+-- characters as with @Prelude.unwords . Prelude.words@
+words
+ :: (Monad m) => Lens' (Producer Text m r) (FreeT (Producer Text m) m r)
+words k p = fmap _unwords (k (_words p))
+{-# INLINABLE words #-}
+unwords
+ :: Monad m
+ => Lens' (FreeT (Producer Text m) m r) (Producer Text m r)
+unwords k p = fmap _words (k (_unwords p))
+{-# INLINABLE unwords #-}
-
--- | Split a text stream into 'FreeT'-delimited words
-words
- :: (Monad m) => Iso'_ (Producer Text m r) (FreeT (Producer Text m) m r)
-words = Data.Profunctor.dimap go (fmap _unwords)
- where
- go p = FreeT $ do
- x <- next (p >-> dropWhile isSpace)
+_words :: (Monad m) => Producer Text m r -> FreeT (Producer Text m) m r
+_words p = FreeT $ do
+ x <- next (dropWhile isSpace p)
return $ case x of
Left r -> Pure r
Right (bs, p') -> Free $ do
p'' <- (yield bs >> p') ^. break isSpace
- return (go p'')
- _unwords = PG.intercalates (yield $ T.singleton ' ')
-
-{-# INLINABLE words #-}
+ return (_words p'')
+{-# INLINABLE _words #-}
+
+_unwords :: (Monad m) => FreeT (Producer Text m) m r -> Producer Text m r
+_unwords = intercalates (yield $ T.singleton ' ')
+{-# INLINABLE _unwords #-}
{-| 'intercalate' concatenates the 'FreeT'-delimited text streams after
-}
intercalate
:: (Monad m)
- => Producer Text m ()
- -> FreeT (Producer Text m) m r
- -> Producer Text m r
+ => Producer Text m () -> FreeT (Producer Text m) m r -> Producer Text m r
intercalate p0 = go0
where
go0 f = do
go1 f'
{-# INLINABLE intercalate #-}
-{-| Join 'FreeT'-delimited lines into a text stream
--}
-unlines
- :: (Monad m)
- => Lens (FreeT (Producer Text m) m x)
- (FreeT (Producer Text m) m y)
- (Producer Text m x)
- (Producer Text m y)
-
-unlines k p = fmap _lines (k (_unlines p))
-{-# INLINABLE unlines #-}
-
-{-| Join 'FreeT'-delimited words into a text stream
--}
-unwords
- :: (Monad m) => FreeT (Producer Text m) m r -> Producer Text m r
-unwords = intercalate (yield $ T.singleton ' ')
-{-# INLINABLE unwords #-}
{- $reexports
-
+
@Data.Text@ re-exports the 'Text' type.
- @Pipes.Parse@ re-exports 'input', 'concat', 'FreeT' (the type) and the 'Parse' synonym.
+ @Pipes.Parse@ re-exports 'input', 'concat', 'FreeT' (the type) and the 'Parse' synonym.
-}
+type Lens' a b = forall f . Functor f => (b -> f b) -> (a -> f a)
projects / github / fretlink / text-pipes.git / blobdiff