-{-# LANGUAGE RankNTypes, TypeFamilies, CPP #-}
+{-# LANGUAGE RankNTypes, TypeFamilies, BangPatterns, Trustworthy #-}
-{-| This module provides @pipes@ utilities for \"text streams\", which are
- streams of 'Text' chunks. The individual chunks are uniformly @strict@, but
- a 'Producer' can be converted to and from lazy 'Text's; an 'IO.Handle' can
- be associated with a 'Producer' or 'Consumer' according as it is read or written to.
-
- To stream to or from 'IO.Handle's, one can use 'fromHandle' or 'toHandle'. For
- example, the following program copies a document from one file to another:
-
-> import Pipes
-> import qualified Data.Text.Pipes as Text
-> import System.IO
->
-> main =
-> withFile "inFile.txt" ReadMode $ \hIn ->
-> withFile "outFile.txt" WriteMode $ \hOut ->
-> runEffect $ Text.fromHandle hIn >-> Text.toHandle hOut
-
-To stream from files, the following is perhaps more Prelude-like (note that it uses Pipes.Safe):
-
-> import Pipes
-> import qualified Data.Text.Pipes as Text
-> import Pipes.Safe
->
-> main = runSafeT $ runEffect $ Text.readFile "inFile.txt" >-> Text.writeFile "outFile.txt"
-
- You can stream to and from 'stdin' and 'stdout' using the predefined 'stdin'
- and 'stdout' proxies, as with the following \"echo\" program:
-
-> main = runEffect $ Text.stdin >-> Text.stdout
-
- You can also translate pure lazy 'TL.Text's to and from proxies:
-
-> main = runEffect $ Text.fromLazy (TL.pack "Hello, world!\n") >-> Text.stdout
-
- In addition, this module provides many functions equivalent to lazy
- 'Text' functions so that you can transform or fold text streams. 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.Parse as Parse
->
-> main = runEffect $ takeLines 3 Text.stdin >-> Text.stdout
-> where
-> takeLines n = Text.unlines . Parse.takeFree n . 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.
-
- Note that functions in this library 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/. However, they will
- /never concatenate texts/ in order to provide strict upper bounds on memory
- usage.
--}
module Pipes.Text (
- -- * Producers
- fromLazy,
- stdin,
- fromHandle,
- readFile,
- stdinLn,
+ -- * Effectful Text
+ -- $intro
+
+ -- * Lenses
+ -- $lenses
+
+ -- ** @view@ \/ @(^.)@
+ -- $view
- -- * Consumers
- stdout,
- stdoutLn,
- toHandle,
- writeFile,
+ -- ** @over@ \/ @(%~)@
+ -- $over
+
+ -- ** @zoom@
+ -- $zoom
+
+ -- * Special types: @Producer Text m (Producer Text m r)@ and @FreeT (Producer Text m) m r@
+ -- $special
+
+ -- * Producers
+ fromLazy
-- * Pipes
- map,
- concatMap,
- take,
- drop,
- takeWhile,
- dropWhile,
- filter,
- scan,
- encodeUtf8,
-#if MIN_VERSION_text(0,11,4)
- pipeDecodeUtf8,
- pipeDecodeUtf8With,
-#endif
- pack,
- unpack,
- toCaseFold,
- toLower,
- toUpper,
- stripStart,
+ , map
+ , concatMap
+ , take
+ , drop
+ , takeWhile
+ , dropWhile
+ , filter
+ , scan
+ , pack
+ , unpack
+ , toCaseFold
+ , toLower
+ , toUpper
+ , stripStart
-- * Folds
- toLazy,
- toLazyM,
- fold,
- head,
- last,
- null,
- length,
- any,
- all,
- maximum,
- minimum,
- find,
- index,
- count,
+ , toLazy
+ , toLazyM
+ , foldChars
+ , head
+ , last
+ , null
+ , length
+ , any
+ , all
+ , maximum
+ , minimum
+ , find
+ , index
+ , count
+
+ -- * Primitive Character Parsers
+ , nextChar
+ , drawChar
+ , unDrawChar
+ , peekChar
+ , isEndOfChars
+
+ -- * Parsing Lenses
+ , splitAt
+ , span
+ , break
+ , groupBy
+ , group
+ , word
+ , line
+
+ -- * FreeT Splitters
+ , chunksOf
+ , splitsWith
+ , splits
+ , groupsBy
+ , groups
+ , lines
+ , words
- -- * Splitters
- splitAt,
- chunksOf,
- span,
- break,
- splitWith,
- split,
- groupBy,
- group,
- lines,
- words,
-#if MIN_VERSION_text(0,11,4)
- decodeUtf8,
- decodeUtf8With,
-#endif
-- * Transformations
- intersperse,
+ , intersperse
+ , packChars
-- * Joiners
- intercalate,
- unlines,
- unwords,
-
- -- * Character Parsers
- -- $parse
- nextChar,
- drawChar,
- unDrawChar,
- peekChar,
- isEndOfChars,
+ , intercalate
+ , unlines
+ , unwords
-- * Re-exports
-- $reexports
- module Data.Text,
- module Pipes.Parse
+ , module Data.ByteString
+ , module Data.Text
+ , module Data.Profunctor
+ , module Pipes.Parse
+ , module Pipes.Group
) where
-import Control.Exception (throwIO, try)
-import Control.Monad (liftM, unless)
-import Control.Monad.Trans.State.Strict (StateT(..))
+import Control.Applicative ((<*))
+import Control.Monad (liftM, join)
+import Control.Monad.Trans.State.Strict (StateT(..), modify)
import qualified Data.Text as T
-import qualified Data.Text.IO as T
-import qualified Data.Text.Encoding as TE
-import qualified Data.Text.Encoding.Error as TE
import Data.Text (Text)
import qualified Data.Text.Lazy as TL
-import qualified Data.Text.Lazy.IO as TL
-import Data.Text.Lazy.Internal (foldrChunks, defaultChunkSize)
-import Data.ByteString.Unsafe (unsafeTake, unsafeDrop)
import Data.ByteString (ByteString)
-import qualified Data.ByteString as B
-import Data.Char (ord, isSpace)
+import Data.Functor.Constant (Constant(Constant, getConstant))
import Data.Functor.Identity (Identity)
-import qualified Data.List as List
-import Foreign.C.Error (Errno(Errno), ePIPE)
-import qualified GHC.IO.Exception as G
+import Data.Profunctor (Profunctor)
+import qualified Data.Profunctor
import Pipes
-import qualified Pipes.ByteString.Parse as PBP
-import Pipes.Text.Parse (
- nextChar, drawChar, unDrawChar, peekChar, isEndOfChars )
-import Pipes.Core (respond, Server')
+import Pipes.Group (concats, intercalates, FreeT(..), FreeF(..))
+import qualified Pipes.Group as PG
import qualified Pipes.Parse as PP
-import Pipes.Parse (input, concat, FreeT)
-import qualified Pipes.Safe.Prelude as Safe
-import qualified Pipes.Safe as Safe
-import Pipes.Safe (MonadSafe(..), Base(..))
+import Pipes.Parse (Parser)
+import Pipes.Text.Encoding (Lens'_, Iso'_)
import qualified Pipes.Prelude as P
-import qualified System.IO as IO
import Data.Char (isSpace)
import Data.Word (Word8)
+import Foreign.Storable (sizeOf)
+import Data.Bits (shiftL)
import Prelude hiding (
all,
any,
words,
writeFile )
--- | Convert a lazy 'TL.Text' into a 'Producer' of strict 'Text's
-fromLazy :: (Monad m) => TL.Text -> Producer' Text m ()
-fromLazy = foldrChunks (\e a -> yield e >> a) (return ())
-{-# INLINABLE fromLazy #-}
+{- $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:
--- | Stream text from 'stdin'
-stdin :: MonadIO m => Producer' Text m ()
-stdin = fromHandle IO.stdin
-{-# INLINABLE stdin #-}
+> 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
-{-| Convert a 'IO.Handle' into a text stream using a text size
- determined by the good sense of the text library.
+ 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
-fromHandle :: MonadIO m => IO.Handle -> Producer' Text m ()
-fromHandle h = go where
- go = do txt <- liftIO (T.hGetChunk h)
- unless (T.null txt) $ do yield txt
- go
-{-# INLINABLE fromHandle#-}
+ 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
-{-| Stream text from a file using Pipes.Safe
+> 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:
->>> runSafeT $ runEffect $ Text.readFile "hello.hs" >-> Text.map toUpper >-> hoist lift Text.stdout
-MAIN = PUTSTRLN "HELLO WORLD"
-}
+{- $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:
-readFile :: (MonadSafe m, Base m ~ IO) => FilePath -> Producer' Text m ()
-readFile file = Safe.withFile file IO.ReadMode fromHandle
-{-# INLINABLE readFile #-}
-{-| Stream lines of text from stdin (for testing in ghci etc.)
+ > 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)
->>> let safely = runSafeT . runEffect
->>> safely $ for Text.stdinLn (lift . lift . print . T.length)
-hello
-5
-world
-5
+-}
+{- $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.
-}
-stdinLn :: MonadIO m => Producer' Text m ()
-stdinLn = go where
- go = do
- eof <- liftIO (IO.hIsEOF IO.stdin)
- unless eof $ do
- txt <- liftIO (T.hGetLine IO.stdin)
- yield txt
- go
+{- $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]
-{-| Stream text to 'stdout'
+ which relate a Text with a pair of Texts or a list of Texts.
+ The corresponding functions here (taking account of \'lensification\') are
- Unlike 'toHandle', 'stdout' gracefully terminates on a broken output pipe.
+> 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
- Note: For best performance, use @(for source (liftIO . putStr))@ instead of
- @(source >-> stdout)@ in suitable cases.
--}
-stdout :: MonadIO m => Consumer' Text m ()
-stdout = go
- where
- go = do
- txt <- await
- x <- liftIO $ try (T.putStr txt)
- case x of
- Left (G.IOError { G.ioe_type = G.ResourceVanished
- , G.ioe_errno = Just ioe })
- | Errno ioe == ePIPE
- -> return ()
- Left e -> liftIO (throwIO e)
- Right () -> go
-{-# INLINABLE stdout #-}
-
-stdoutLn :: (MonadIO m) => Consumer' Text m ()
-stdoutLn = go
- where
- go = do
- str <- await
- x <- liftIO $ try (T.putStrLn str)
- case x of
- Left (G.IOError { G.ioe_type = G.ResourceVanished
- , G.ioe_errno = Just ioe })
- | Errno ioe == ePIPE
- -> return ()
- Left e -> liftIO (throwIO e)
- Right () -> go
-{-# INLINABLE stdoutLn #-}
-
-{-| Convert a text stream into a 'Handle'
-
- Note: again, for best performance, where possible use
- @(for source (liftIO . hPutStr handle))@ instead of @(source >-> toHandle handle)@.
+ 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.
+
-}
-toHandle :: MonadIO m => IO.Handle -> Consumer' Text m r
-toHandle h = for cat (liftIO . T.hPutStr h)
-{-# INLINABLE toHandle #-}
-{-# RULES "p >-> toHandle h" forall p h .
- p >-> toHandle h = for p (\txt -> liftIO (T.hPutStr h txt))
- #-}
+-- | Convert a lazy 'TL.Text' into a 'Producer' of strict 'Text's
+fromLazy :: (Monad m) => TL.Text -> Producer' Text m ()
+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)
--- | Stream text into a file. Uses @pipes-safe@.
-writeFile :: (MonadSafe m, Base m ~ IO) => FilePath -> Consumer' Text m ()
-writeFile file = Safe.withFile file IO.WriteMode toHandle
-- | Apply a transformation to each 'Char' in the stream
map :: (Monad m) => (Char -> Char) -> Pipe Text Text m r
p >-> concatMap f = for p (\txt -> yield (T.concatMap f txt))
#-}
--- | Transform a Pipe of 'Text' into a Pipe of 'ByteString's using UTF-8
--- encoding; @encodeUtf8 = Pipes.Prelude.map TE.encodeUtf8@ so more complex
--- encoding pipes can easily be constructed with the functions in @Data.Text.Encoding@
-encodeUtf8 :: Monad m => Pipe Text ByteString m r
-encodeUtf8 = P.map TE.encodeUtf8
-{-# INLINEABLE encodeUtf8 #-}
-
-{-# RULES "p >-> encodeUtf8" forall p .
- p >-> encodeUtf8 = for p (\txt -> yield (TE.encodeUtf8 txt))
- #-}
-- | Transform a Pipe of 'String's into one of 'Text' chunks
pack :: Monad m => Pipe String Text m r
p >-> unpack = for p (\txt -> yield (T.unpack txt))
#-}
--- | @toCaseFold@, @toLower@, @toUpper@ and @stripStart@ are standard 'Text' utility,
--- here acting on a 'Text' pipe, rather as they would on a lazy text
-toCaseFold :: Monad m => Pipe Text Text m ()
+-- | @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 ()
+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 ()
+toUpper :: Monad m => Pipe Text Text m r
toUpper = P.map T.toUpper
{-# INLINEABLE toUpper #-}
let text = T.stripStart chunk
if T.null text
then stripStart
- else cat
+ else do yield text
+ cat
{-# INLINEABLE stripStart #-}
-- | @(take n)@ only allows @n@ individual characters to pass;
scan
:: (Monad m)
=> (Char -> Char -> Char) -> Char -> Pipe Text Text m r
-scan step begin = go begin
+scan step begin = do
+ yield (T.singleton begin)
+ go begin
where
go c = do
txt <- await
let txt' = T.scanl step c txt
c' = T.last txt'
- yield txt'
+ yield (T.tail txt')
go c'
{-# INLINABLE scan #-}
{-# INLINABLE toLazyM #-}
-- | Reduce the text stream using a strict left fold over characters
-fold
+foldChars
:: Monad m
=> (x -> Char -> x) -> x -> (x -> r) -> Producer Text m () -> m r
-fold step begin done = P.fold (T.foldl' step) begin done
-{-# INLINABLE fold #-}
+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)
count c p = P.fold (+) 0 id (p >-> P.map (fromIntegral . T.count c))
{-# INLINABLE count #-}
-#if MIN_VERSION_text(0,11,4)
--- | Transform a Pipe of 'ByteString's expected to be UTF-8 encoded
--- into a Pipe of Text
-decodeUtf8
- :: Monad m
- => Producer ByteString m r -> Producer Text m (Producer ByteString m r)
-decodeUtf8 = go TE.streamDecodeUtf8
- where go dec p = do
- x <- lift (next p)
- case x of
- Left r -> return (return r)
- Right (chunk, p') -> do
- let TE.Some text l dec' = dec chunk
- if B.null l
- then do
- yield text
- go dec' p'
- else return $ do
- yield l
- p'
-{-# INLINEABLE decodeUtf8 #-}
-
--- | Transform a Pipe of 'ByteString's expected to be UTF-8 encoded
--- into a Pipe of Text with a replacement function of type @String -> Maybe Word8 -> Maybe Char@
--- E.g. 'Data.Text.Encoding.Error.lenientDecode', which simply replaces bad bytes with \"�\"
-decodeUtf8With
- :: Monad m
- => TE.OnDecodeError
- -> Producer ByteString m r -> Producer Text m (Producer ByteString m r)
-decodeUtf8With onErr = go (TE.streamDecodeUtf8With onErr)
- where go dec p = do
- x <- lift (next p)
- case x of
- Left r -> return (return r)
- Right (chunk, p') -> do
- let TE.Some text l dec' = dec chunk
- if B.null l
- then do
- yield text
- go dec' p'
- else return $ do
- yield l
- p'
-{-# INLINEABLE decodeUtf8With #-}
-
--- | A simple pipe from 'ByteString' to 'Text'; a decoding error will arise
--- with any chunk that contains a sequence of bytes that is unreadable. Otherwise
--- only few bytes will only be moved from one chunk to the next before decoding.
-pipeDecodeUtf8 :: Monad m => Pipe ByteString Text m r
-pipeDecodeUtf8 = go TE.streamDecodeUtf8
- where go dec = do chunk <- await
- case dec chunk of
- TE.Some text l dec' -> do yield text
- go dec'
-{-# INLINEABLE pipeDecodeUtf8 #-}
-
--- | A simple pipe from 'ByteString' to 'Text' using a replacement function.
-pipeDecodeUtf8With
- :: Monad m
- => TE.OnDecodeError
- -> Pipe ByteString Text m r
-pipeDecodeUtf8With onErr = go (TE.streamDecodeUtf8With onErr)
- where go dec = do chunk <- await
- case dec chunk of
- TE.Some text l dec' -> do yield text
- go dec'
-{-# INLINEABLE pipeDecodeUtf8With #-}
-#endif
+
+-- | 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'.
+
+nextChar
+ :: (Monad m)
+ => Producer Text m r
+ -> m (Either r (Char, Producer Text m r))
+nextChar = go
+ where
+ go p = do
+ x <- next p
+ case x of
+ Left r -> return (Left r)
+ Right (txt, p') -> case (T.uncons txt) of
+ Nothing -> go p'
+ Just (c, txt') -> return (Right (c, yield txt' >> p'))
+{-# INLINABLE nextChar #-}
+
+-- | Draw one 'Char' from a stream of 'Text', returning 'Left' if the 'Producer' is empty
+
+drawChar :: (Monad m) => Parser Text m (Maybe Char)
+drawChar = do
+ x <- PP.draw
+ case x of
+ Nothing -> return Nothing
+ Just txt -> case (T.uncons txt) of
+ Nothing -> drawChar
+ Just (c, txt') -> do
+ PP.unDraw txt'
+ return (Just c)
+{-# INLINABLE drawChar #-}
+
+-- | Push back a 'Char' onto the underlying 'Producer'
+unDrawChar :: (Monad m) => Char -> Parser Text m ()
+unDrawChar c = modify (yield (T.singleton c) >>)
+{-# INLINABLE unDrawChar #-}
+
+{-| 'peekChar' checks the first 'Char' in the stream, but uses 'unDrawChar' to
+ push the 'Char' back
+
+> peekChar = do
+> x <- drawChar
+> case x of
+> Left _ -> return ()
+> Right c -> unDrawChar c
+> return x
+
+-}
+
+peekChar :: (Monad m) => Parser Text m (Maybe Char)
+peekChar = do
+ x <- drawChar
+ case x of
+ Nothing -> return ()
+ Just c -> unDrawChar c
+ return x
+{-# INLINABLE peekChar #-}
+
+{-| Check if the underlying 'Producer' has no more characters
+
+ Note that this will skip over empty 'Text' chunks, unlike
+ 'PP.isEndOfInput' from @pipes-parse@, which would consider
+ an empty 'Text' a valid bit of input.
+
+> isEndOfChars = liftM isLeft peekChar
+-}
+isEndOfChars :: (Monad m) => Parser Text m Bool
+isEndOfChars = do
+ x <- peekChar
+ return (case x of
+ Nothing -> True
+ Just _-> False )
+{-# INLINABLE isEndOfChars #-}
+
-- | Splits a 'Producer' after the given number of characters
splitAt
:: (Monad m, Integral n)
=> n
- -> Producer Text m r
- -> Producer' Text m (Producer Text m r)
-splitAt = go
+ -> 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
go n p = do
return (yield suffix >> p')
{-# INLINABLE splitAt #-}
--- | Split a text stream into 'FreeT'-delimited text streams of fixed size
-chunksOf
- :: (Monad m, Integral n)
- => n -> Producer Text m r -> FreeT (Producer Text m) m r
-chunksOf n p0 = PP.FreeT (go p0)
- where
- go p = do
- x <- next p
- return $ case x of
- Left r -> PP.Pure r
- Right (txt, p') -> PP.Free $ do
- p'' <- splitAt n (yield txt >> p')
- return $ PP.FreeT (go p'')
-{-# INLINABLE chunksOf #-}
-{-| Split a text stream in two, where the first text stream is the longest
- consecutive group of text that satisfy the predicate
--}
+-- | Split a text stream in two, producing the longest
+-- consecutive group of characters that satisfies the predicate
+-- and returning the rest
+
span
:: (Monad m)
=> (Char -> Bool)
- -> Producer Text m r
- -> Producer' Text m (Producer Text m r)
-span predicate = go
+ -> 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
x <- lift (next p)
return (yield suffix >> p')
{-# INLINABLE span #-}
-{-| Split a text stream in two, where the first text stream is the longest
+{-| Split a text stream in two, producing the longest
consecutive group of characters that don't satisfy the predicate
-}
break
:: (Monad m)
=> (Char -> Bool)
- -> Producer Text m r
- -> Producer Text m (Producer Text m r)
+ -> Lens'_ (Producer Text m r)
+ (Producer Text m (Producer Text m r))
break predicate = span (not . predicate)
{-# INLINABLE break #-}
-{-| Split a text stream into sub-streams delimited by characters that satisfy the
- predicate
--}
-splitWith
- :: (Monad m)
- => (Char -> Bool)
- -> Producer Text m r
- -> PP.FreeT (Producer Text m) m r
-splitWith predicate p0 = PP.FreeT (go0 p0)
- where
- go0 p = do
- x <- next p
- case x of
- Left r -> return (PP.Pure r)
- Right (txt, p') ->
- if (T.null txt)
- then go0 p'
- else return $ PP.Free $ do
- p'' <- span (not . predicate) (yield txt >> p')
- return $ PP.FreeT (go1 p'')
- go1 p = do
- x <- nextChar p
- return $ case x of
- Left r -> PP.Pure r
- Right (_, p') -> PP.Free $ do
- p'' <- span (not . predicate) p'
- return $ PP.FreeT (go1 p'')
-{-# INLINABLE splitWith #-}
-
--- | Split a text stream using the given 'Char' as the delimiter
-split :: (Monad m)
- => Char
- -> Producer Text m r
- -> FreeT (Producer Text m) m r
-split c = splitWith (c ==)
-{-# INLINABLE split #-}
-
-{-| Group a text stream into 'FreeT'-delimited text streams using the supplied
- equality predicate
+{-| Improper lens that splits after the first group of equivalent Chars, as
+ defined by the given equivalence relation
-}
groupBy
:: (Monad m)
=> (Char -> Char -> Bool)
- -> Producer Text m r
- -> FreeT (Producer Text m) m r
-groupBy equal p0 = PP.FreeT (go p0)
- where
+ -> 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 <- next p
+ x <- lift (next p)
case x of
- Left r -> return (PP.Pure r)
- Right (txt, p') -> case (T.uncons txt) of
+ Left r -> return (return r)
+ Right (txt, p') -> case T.uncons txt of
Nothing -> go p'
- Just (c, _) -> do
- return $ PP.Free $ do
- p'' <- span (equal c) (yield txt >> p')
- return $ PP.FreeT (go p'')
+ Just (c, _) -> (yield txt >> p') ^. span (equals c)
{-# INLINABLE groupBy #-}
--- | Group a text stream into 'FreeT'-delimited text streams of identical characters
-group
- :: (Monad m) => Producer Text m r -> FreeT (Producer Text m) m r
+-- | Improper lens that splits after the first succession of identical 'Char' s
+group :: Monad m
+ => Lens'_ (Producer Text m r)
+ (Producer Text m (Producer Text m r))
group = groupBy (==)
{-# INLINABLE group #-}
-{-| Split a text stream into 'FreeT'-delimited lines
+{-| Improper lens that splits a 'Producer' after the first word
+
+ Unlike 'words', this does not drop leading whitespace
-}
-lines
- :: (Monad m) => Producer Text m r -> FreeT (Producer Text m) m r
-lines p0 = PP.FreeT (go0 p0)
+word :: (Monad m)
+ => Lens'_ (Producer Text m r)
+ (Producer Text m (Producer Text m r))
+word k p0 = fmap join (k (to p0))
where
- go0 p = do
- x <- next p
- case x of
- Left r -> return (PP.Pure r)
- Right (txt, p') ->
- if (T.null txt)
- then go0 p'
- else return $ PP.Free $ go1 (yield txt >> p')
- go1 p = do
- p' <- break ('\n' ==) p
- return $ PP.FreeT $ do
- x <- nextChar p'
- case x of
- Left r -> return $ PP.Pure r
- Right (_, p'') -> go0 p''
-{-# INLINABLE lines #-}
+ to p = do
+ p' <- p^.span isSpace
+ p'^.break isSpace
+{-# INLINABLE word #-}
+line :: (Monad m)
+ => Lens'_ (Producer Text m r)
+ (Producer Text m (Producer Text m r))
+line = break (== '\n')
--- | Split a text stream into 'FreeT'-delimited words
-words
- :: (Monad m) => Producer Text m r -> FreeT (Producer Text m) m r
-words = go
- where
- go p = PP.FreeT $ do
- x <- next (p >-> dropWhile isSpace)
- return $ case x of
- Left r -> PP.Pure r
- Right (bs, p') -> PP.Free $ do
- p'' <- break isSpace (yield bs >> p')
- return (go p'')
-{-# INLINABLE words #-}
+{-# INLINABLE line #-}
--- | Intersperse a 'Char' in between the characters of the text stream
+-- | Intersperse a 'Char' in between the characters of stream of 'Text'
intersperse
:: (Monad m) => Char -> Producer Text m r -> Producer Text m r
intersperse c = go0
go1 p'
{-# INLINABLE intersperse #-}
+
+
+-- | 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)
+
+ step diffAs c = diffAs . (c:)
+
+ done diffAs = T.pack (diffAs [])
+
+ -- from :: Monad m => Producer Text m x -> Producer Char m x
+ from p = for p (each . T.unpack)
+
+{-# INLINABLE packChars #-}
+
+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 r)
+ (FreeT (Producer Text m) m r)
+chunksOf n k p0 = fmap concats (k (FreeT (go p0)))
+ where
+ go p = do
+ x <- next p
+ return $ case x of
+ Left r -> Pure r
+ Right (txt, p') -> Free $ do
+ p'' <- (yield txt >> p') ^. splitAt n
+ return $ FreeT (go p'')
+{-# INLINABLE chunksOf #-}
+
+
+{-| Split a text stream into sub-streams delimited by characters that satisfy the
+ predicate
+-}
+splitsWith
+ :: (Monad m)
+ => (Char -> Bool)
+ -> Producer Text m r
+ -> FreeT (Producer Text m) m r
+splitsWith predicate p0 = FreeT (go0 p0)
+ where
+ go0 p = do
+ x <- next p
+ case x of
+ Left r -> return (Pure r)
+ Right (txt, p') ->
+ if (T.null txt)
+ then go0 p'
+ else return $ Free $ do
+ p'' <- (yield txt >> p') ^. span (not . predicate)
+ return $ FreeT (go1 p'')
+ go1 p = do
+ x <- nextChar p
+ return $ case x of
+ Left r -> Pure r
+ Right (_, p') -> Free $ do
+ 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 r)
+ (FreeT (Producer Text m) m r)
+splits c k p =
+ fmap (PG.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
+ given equivalence relation
+-}
+groupsBy
+ :: Monad m
+ => (Char -> Char -> Bool)
+ -> 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
+ Nothing -> go p'
+ Just (c, _) -> do return $ Free $ do
+ p'' <- (yield bs >> p')^.span (equals c)
+ return $ FreeT (go p'')
+{-# INLINABLE groupsBy #-}
+
+
+-- | Like 'groupsBy', where the equality predicate is ('==')
+groups
+ :: Monad m
+ => 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) => Iso'_ (Producer Text m r) (FreeT (Producer Text m) m r)
+lines = Data.Profunctor.dimap _lines (fmap _unlines)
+ where
+ _lines p0 = FreeT (go0 p0)
+ where
+ go0 p = do
+ x <- next p
+ case x of
+ Left r -> return (Pure r)
+ Right (txt, p') ->
+ if (T.null txt)
+ then go0 p'
+ else return $ Free $ go1 (yield txt >> p')
+ go1 p = do
+ p' <- p ^. break ('\n' ==)
+ return $ FreeT $ do
+ x <- nextChar p'
+ case x of
+ Left r -> return $ Pure r
+ Right (_, p'') -> go0 p''
+ -- _unlines
+ -- :: Monad m
+ -- => FreeT (Producer Text m) m x -> Producer Text m x
+ _unlines = concats . PG.maps (<* yield (T.singleton '\n'))
+
+
+{-# INLINABLE lines #-}
+
+
+-- | 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)
+ 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 #-}
+
+
{-| 'intercalate' concatenates the 'FreeT'-delimited text streams after
interspersing a text stream in between them
-}
intercalate p0 = go0
where
go0 f = do
- x <- lift (PP.runFreeT f)
+ x <- lift (runFreeT f)
case x of
- PP.Pure r -> return r
- PP.Free p -> do
+ Pure r -> return r
+ Free p -> do
f' <- p
go1 f'
go1 f = do
- x <- lift (PP.runFreeT f)
+ x <- lift (runFreeT f)
case x of
- PP.Pure r -> return r
- PP.Free p -> do
+ Pure r -> return r
+ Free p -> do
p0
f' <- p
go1 f'
unlines = go
where
go f = do
- x <- lift (PP.runFreeT f)
+ x <- lift (runFreeT f)
case x of
- PP.Pure r -> return r
- PP.Free p -> do
+ Pure r -> return r
+ Free p -> do
f' <- p
yield $ T.singleton '\n'
go f'
-}
unwords
:: (Monad m) => FreeT (Producer Text m) m r -> Producer Text m r
-unwords = intercalate (yield $ T.pack " ")
+unwords = intercalate (yield $ T.singleton ' ')
{-# INLINABLE unwords #-}
-{- $parse
- The following parsing utilities are single-character analogs of the ones found
- @pipes-parse@.
--}
{- $reexports
- @Pipes.Text.Parse@ re-exports 'nextChar', 'drawChar', 'unDrawChar', 'peekChar', and 'isEndOfChars'.
@Data.Text@ re-exports the 'Text' type.
- @Pipes.Parse@ re-exports 'input', 'concat', and 'FreeT' (the type).
--}
\ No newline at end of file
+ @Pipes.Parse@ re-exports 'input', 'concat', 'FreeT' (the type) and the 'Parse' synonym.
+-}
+
+
projects / github / fretlink / text-pipes.git / blobdiff