{-| This module provides @pipes@ utilities for \"text streams\", which are
streams of 'Text' chunks. The individual chunks are uniformly @strict@, but
- can interact lazy 'Text's and 'IO.Handle's.
+ 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, use 'fromHandle' or 'toHandle'. For
+ 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
filter,
scan,
encodeUtf8,
+#if MIN_VERSION_text(0,11,4)
+ pipeDecodeUtf8,
+ pipeDecodeUtf8With,
+#endif
pack,
unpack,
toCaseFold,
minimum,
find,
index,
--- elemIndex,
--- findIndex,
count,
-- * Splitters
words,
#if MIN_VERSION_text(0,11,4)
decodeUtf8,
+ decodeUtf8With,
#endif
-- * Transformations
intersperse,
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.ByteString.Unsafe (unsafeTake, unsafeDrop)
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
-import Data.Char (ord)
+import Data.Char (ord, isSpace)
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 Pipes
+import qualified Pipes.ByteString as PB
import qualified Pipes.ByteString.Parse as PBP
import Pipes.Text.Parse (
nextChar, drawChar, unDrawChar, peekChar, isEndOfChars )
import qualified Pipes.Prelude as P
import qualified System.IO as IO
import Data.Char (isSpace)
+import Data.Word (Word8)
import Prelude hiding (
all,
any,
-}
fromHandle :: MonadIO m => IO.Handle -> Producer' Text m ()
+#if MIN_VERSION_text(0,11,4)
+fromHandle h = go TE.streamDecodeUtf8 where
+ act = B.hGetSome h defaultChunkSize
+ go dec = do chunk <- liftIO act
+ case dec chunk of
+ TE.Some text _ dec' -> do yield text
+ unless (B.null chunk) (go dec')
+{-# INLINE fromHandle#-}
+-- bytestring fromHandle + streamDecodeUtf8 is 3 times as fast as
+-- the dedicated Text IO function 'hGetChunk' ;
+-- this way "runEffect $ PT.fromHandle hIn >-> PT.toHandle hOut"
+-- runs the same as the conduit equivalent, only slightly slower
+-- than "runEffect $ PB.fromHandle hIn >-> PB.toHandle hOut"
+#else
fromHandle h = go where
go = do txt <- liftIO (T.hGetChunk h)
unless (T.null txt) $ do yield txt
go
{-# INLINABLE fromHandle#-}
-
+#endif
{-| Stream text from a file using Pipes.Safe
>>> runSafeT $ runEffect $ Text.readFile "hello.hs" >-> Text.map toUpper >-> hoist lift Text.stdout
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))
+ #-}
+
+
-- | 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
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 'Text' into a Pipe of 'ByteString's using UTF-8
--- encoding
+-- 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
pack = P.map T.pack
{-# INLINEABLE pack #-}
--- | Transforma a Pipes of 'Text' chunks into one of 'String's
+{-# 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 = P.map T.unpack
+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' utility,
-- here acting on a 'Text' pipe, rather as they would on a lazy text
toCaseFold :: Monad m => Pipe Text Text m ()
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 ()
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 ()
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
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
scan
:: (Monad m)
index n p = head (p >-> drop n)
{-# INLINABLE index #-}
--- | Find the index of an element that matches the given 'Char'
--- elemIndex
--- :: (Monad m, Num n) => Char -> Producer Text m () -> m (Maybe n)
--- elemIndex w8 = findIndex (w8 ==)
--- {-# INLINABLE elemIndex #-}
-
--- | Store the first index of an element that satisfies the predicate
--- findIndex
--- :: (Monad m, Num n)
--- => (Char -> Bool) -> Producer Text m () -> m (Maybe n)
--- findIndex predicate p = P.head (p >-> findIndices predicate)
--- {-# INLINABLE findIndex #-}
---
+
-- | 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))
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
-- | Splits a 'Producer' after the given number of characters
else return $ PP.Free $ go1 (yield txt >> p')
go1 p = do
p' <- break ('\n' ==) p
- return $ PP.FreeT (go2 p')
- go2 p = do
- x <- nextChar p
- return $ case x of
- Left r -> PP.Pure r
- Right (_, p') -> PP.Free (go1 p')
+ return $ PP.FreeT $ do
+ x <- nextChar p'
+ case x of
+ Left r -> return $ PP.Pure r
+ Right (_, p'') -> go0 p''
{-# INLINABLE lines #-}
-- | Split a text stream into 'FreeT'-delimited words
words
:: (Monad m) => Producer Text m r -> FreeT (Producer Text m) m r
-words p0 = removeEmpty (splitWith isSpace p0)
+words = go
where
- removeEmpty f = PP.FreeT $ do
- x <- PP.runFreeT f
- case x of
- PP.Pure r -> return (PP.Pure r)
- PP.Free p -> loop p
- loop p = do
- y <- next p
- case y of
- Left f' -> PP.runFreeT (removeEmpty f')
- Right (txt, p') ->
- if T.null txt
- then loop p'
- else return $ PP.Free $ do
- yield txt
- f' <- p'
- return (removeEmpty f')
+ 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 #-}
+
-- | Intersperse a 'Char' in between the characters of the text stream
intersperse
:: (Monad m) => Char -> Producer Text m r -> Producer Text m r
projects / github / fretlink / text-pipes.git / blobdiff