X-Git-Url: https://git.immae.eu/?a=blobdiff_plain;f=Pipes%2FText.hs;h=f2b4aacf5e09892d010ab1273e39b1b2ea3f9bb8;hb=b4d21c025864357dab2b0df07091d953c6da98f3;hp=1092491092d25b078b2ef4299b7e70135dbbae49;hpb=acc6868f63bdbede411874f4cfdbbb2d4bfa41da;p=github%2Ffretlink%2Ftext-pipes.git

diff --git a/Pipes/Text.hs b/Pipes/Text.hs
index 1092491..f2b4aac 100644
--- a/Pipes/Text.hs
+++ b/Pipes/Text.hs
@@ -2,9 +2,10 @@
 
 {-| 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
@@ -80,6 +81,10 @@ module Pipes.Text  (
     filter,
     scan,
     encodeUtf8,
+#if MIN_VERSION_text(0,11,4)
+    pipeDecodeUtf8,
+    pipeDecodeUtf8With,
+#endif
     pack,
     unpack,
     toCaseFold,
@@ -101,8 +106,6 @@ module Pipes.Text  (
     minimum,
     find,
     index,
---    elemIndex,
---    findIndex,
     count,
 
     -- * Splitters
@@ -118,6 +121,7 @@ module Pipes.Text  (
     words,
 #if MIN_VERSION_text(0,11,4)
     decodeUtf8,
+    decodeUtf8With,
 #endif
     -- * Transformations
     intersperse,
@@ -147,6 +151,7 @@ import Control.Monad.Trans.State.Strict (StateT(..))
 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
@@ -154,7 +159,7 @@ 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)
+import Data.Char (ord, isSpace)
 import Data.Functor.Identity (Identity)
 import qualified Data.List as List
 import Foreign.C.Error (Errno(Errno), ePIPE)
@@ -172,6 +177,7 @@ import Pipes.Safe (MonadSafe(..), Base(..))
 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,
@@ -316,7 +322,8 @@ concatMap f = P.map (T.concatMap f)
 
 
 -- | 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 #-}
@@ -542,19 +549,7 @@ index
 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))
@@ -581,6 +576,52 @@ decodeUtf8 = go TE.streamDecodeUtf8
                           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
@@ -740,12 +781,11 @@ lines p0 = PP.FreeT (go0 p0)
                 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 #-}
 
 
@@ -753,26 +793,18 @@ lines p0 = PP.FreeT (go0 p0)
 -- | 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