binary-0.6 compatibility

Ignore-this: 6af2adadedc20f51bb5084b3da59724e

darcs-hash:20121213030806-76d51-6d52680cab9b4f4b6c2ba17e29fa457b85d4d838

Data/Encoding/ByteSource.hs

@@ -6,7 +6,9 @@ import Data.Encoding.Exception
 import Data.Bits
 import Data.Binary.Get
 import Data.Char
+import Data.Maybe
 import Data.Word
+import Control.Applicative as A
 import Control.Monad.State
 import Control.Monad.Identity
 import Control.Monad.Reader
@@ -19,7 +21,9 @@ import System.IO
 class (Monad m,Throws DecodingException m) => ByteSource m where
     sourceEmpty :: m Bool
     fetchWord8 :: m Word8
-    fetchAhead :: m a -> m a
+    -- 'fetchAhead act' should return the same thing 'act' does, but should
+    -- only consume input if 'act' returns a 'Just' value
+    fetchAhead :: m (Maybe a) -> m (Maybe a)
     fetchWord16be :: m Word16
     fetchWord16be = do
       w1 <- fetchWord8
@@ -95,7 +99,20 @@ instance Throws DecodingException Get where
 instance ByteSource Get where
     sourceEmpty = isEmpty
     fetchWord8 = getWord8
-    fetchAhead = lookAhead
+#if MIN_VERSION_binary(0,6,0)
+    fetchAhead act = (do
+        res <- act
+        case res of
+            Nothing -> A.empty
+            Just a  -> return res
+        ) <|> return Nothing
+#else
+    fetchAhead act = do
+        res <- lookAhead act
+        case res of
+            Nothing -> return Nothing
+            Just a  -> act
+#endif
     fetchWord16be = getWord16be
     fetchWord16le = getWord16le
     fetchWord32be = getWord32be
@@ -103,6 +120,12 @@ instance ByteSource Get where
     fetchWord64be = getWord64be
     fetchWord64le = getWord64le
 
+fetchAheadState act = do
+    chs <- get
+    res <- act
+    when (isNothing res) (put chs)
+    return res
+
 instance ByteSource (StateT [Char] Identity) where
     sourceEmpty = gets null
     fetchWord8 = do
@@ -112,11 +135,7 @@ instance ByteSource (StateT [Char] Identity) where
         c:cs -> do
           put cs
           return (fromIntegral $ ord c)
-    fetchAhead act = do
-      chs <- get
-      res <- act
-      put chs
-      return res
+    fetchAhead = fetchAheadState
 
 #if MIN_VERSION_base(4,3,0)
 #else
@@ -135,33 +154,21 @@ instance ByteSource (StateT [Char] (Either DecodingException)) where
         c:cs -> do
           put cs
           return (fromIntegral $ ord c)
-    fetchAhead act = do
-      chs <- get
-      res <- act
-      put chs
-      return res
+    fetchAhead = fetchAheadState
 
 instance (Monad m,Throws DecodingException m) => ByteSource (StateT BS.ByteString m) where
     sourceEmpty = gets BS.null
     fetchWord8 = StateT (\str -> case BS.uncons str of
                                   Nothing -> throwException UnexpectedEnd
                                   Just (c,cs) -> return (c,cs))
-    fetchAhead act = do
-      str <- get
-      res <- act
-      put str
-      return res
+    fetchAhead = fetchAheadState
 
 instance ByteSource (StateT LBS.ByteString (Either DecodingException)) where
     sourceEmpty = gets LBS.null
     fetchWord8 = StateT (\str -> case LBS.uncons str of
                                   Nothing -> Left UnexpectedEnd
                                   Just ns -> Right ns)
-    fetchAhead act = do
-      chs <- get
-      res <- act
-      put chs
-      return res
+    fetchAhead = fetchAheadState
 
 instance ByteSource (ReaderT Handle IO) where
     sourceEmpty = do
@@ -176,5 +183,5 @@ instance ByteSource (ReaderT Handle IO) where
       h <- ask
       pos <- liftIO $ hGetPosn h
       res <- act
-      liftIO $ hSetPosn pos
+      when (isNothing res) (liftIO $ hSetPosn pos)
       return res

Data/Encoding/ISO2022JP.hs

@@ -26,11 +26,10 @@ instance Encoding ISO2022JP where
     encodeable _ c = encodeable ASCII c || encodeable JISX0201 c || encodeable JISX0208 c
 
 instance ISO2022 ISO2022JP where
-    readEscape _ = do
-      w <- fetchAhead fetchWord8
+    readEscape _ = fetchAhead $ do
+      w <- fetchWord8
       if w == 27
         then (do
-               fetchWord8
                w2 <- fetchWord8
                w3 <- fetchWord8
                case w2 of

encoding.cabal

@@ -1,5 +1,5 @@
 Name:		encoding
-Version:	0.6.7.2
+Version:	0.7
 Author:		Henning Günther
 Maintainer:	daniel@wagner-home.com
 License:	BSD3
@@ -24,8 +24,6 @@ Extra-Source-Files:
 
 Flag splitBase
   description:	Choose the new smaller, split-up base package.
-Flag newGHC
-  description: Use ghc version > 6.10
 Flag systemEncoding
   description: Provide the getSystemEncoding action to query the locale.
 
@@ -36,16 +34,14 @@ Source-Repository head
 Source-Repository this
   Type:			darcs
   Location:		http://code.haskell.org/encoding
-  Tag:			0.6.7.1
+  Tag:			0.7
 
 Library
-  Build-Depends:	binary < 0.6, extensible-exceptions, HaXml >= 1.22 && < 1.24
+  Build-Depends:	binary < 0.7, extensible-exceptions, HaXml >= 1.22 && < 1.24
   if flag(splitBase)
     Build-Depends:	bytestring, base >= 3 && < 5, mtl, containers, array, regex-compat
-    if flag(newGHC)
-      Build-Depends:	ghc-prim, ghc >= 6.10
-    else
-      Build-Depends:	ghc < 6.10
+    if impl(ghc >= 6.10)
+      Build-Depends:	ghc-prim
   else
     Build-Depends:	base < 3