Correctly track capacity when initial buffer is empty

This fixes gh-75.
haskell · Aug 26, 2014 · 3c47ecd · 3c47ecd
1 parent 1780eaf
commit 3c47ecd
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/Data/Attoparsec/ByteString/Buffer.hs b/Data/Attoparsec/ByteString/Buffer.hs
@@ -65,6 +65,7 @@ import Foreign.Storable (peek, peekByteOff, poke, sizeOf)
 import GHC.ForeignPtr (mallocPlainForeignPtrBytes)
 import Prelude hiding (length)
 
+-- If _cap is zero, this buffer is empty.
 data Buffer = Buf {
       _fp  :: {-# UNPACK #-} !(ForeignPtr Word8)
     , _off :: {-# UNPACK #-} !Int
@@ -96,7 +97,7 @@ instance Monoid Buffer where
     mconcat xs = foldl1' mappend xs
 
 pappend :: Buffer -> ByteString -> Buffer
-pappend (Buf _ _ _ 0 _) (PS fp off len) = Buf fp off len 0 0
+pappend (Buf _ _ _ 0 _) bs  = buffer bs
 pappend buf (PS fp off len) = append buf fp off len
 
 append :: Buffer -> ForeignPtr a -> Int -> Int -> Buffer

diff --git a/Data/Attoparsec/Text/Buffer.hs b/Data/Attoparsec/Text/Buffer.hs
@@ -51,6 +51,7 @@ import GHC.ST (ST(..), runST)
 import Prelude hiding (length)
 import qualified Data.Text.Array as A
 
+-- If _cap is zero, this buffer is empty.
 data Buffer = Buf {
       _arr :: {-# UNPACK #-} !A.Array
     , _off :: {-# UNPACK #-} !Int
@@ -82,8 +83,8 @@ instance Monoid Buffer where
     mconcat xs = foldl1' mappend xs
 
 pappend :: Buffer -> Text -> Buffer
-pappend (Buf _ _ _ 0 _) (Text arr off len) = Buf arr off len 0 0
-pappend buf (Text arr off len)             = append buf arr off len
+pappend (Buf _ _ _ 0 _) t      = buffer t
+pappend buf (Text arr off len) = append buf arr off len
 
 append :: Buffer -> A.Array -> Int -> Int -> Buffer
 append (Buf arr0 off0 len0 cap0 gen0) !arr1 !off1 !len1 = runST $ do