On Tue, Jun 2, 2009 at 10:24 AM, Thomas DuBuisson
<thomas.dubuisson@gmail.com> wrote:
> I think getRemainingLazyByteString expects at least one byte
No, it works with an empty bytestring. Or, my tests do with binary 0.5.0.1.
The specific error means you are requiring more data than providing.
I've shown that I am not trying to decode more than I'm providing. I've asked, expliciitly, for 13 bytes, and then "remaining", and the library is complaining about the 20th byte.
First check the length of the bytestring you pass in to the to level
decode (or 'get') routine and walk though that to figure out how much
it should be consuming. I notice you have a guard on the
'getSpecific' function, hopefully you're sure the case you gave us is
the branch being taken.
The other branch is Rerror, which is a shorter message decode stream. Unfortunately, I can't get Debug.Trace to show anything to prove it's taking this fork of the code. I suppose I could unsafePerformIO :-)
Perhaps I just need a new version of "binary"?? I'll give it a go and try your version. But I need to decode over a dozen message types, so I will need a case or guard or something.
Dave
I think the issue isn't with the code provided. I cleaned up the code
(which did change behavior due to the guard and data declarations that
weren't in the mailling) and it works fine all the way down to the
expected minimum of 13 bytes.
> import Data.ByteString.Lazy
> import Data.Binary
> import Data.Binary.Get
>
> data RV =
> Rversion { size :: Word32,
> mtype :: Word8,
> tag :: Word16,
> msize :: Word32,
> ssize :: Word16,
> version :: ByteString}
> deriving (Eq, Ord, Show)
> instance Binary RV where
> get = do s <- getWord32le
> mtype <- getWord8
> getSpecific s mtype
> where
> getSpecific s mt = do t <- getWord16le
> ms <- getWord32le
> ss <- getWord16le
> v <- getRemainingLazyByteString
> return $ Rversion {size=s,
> mtype=mt,
> tag=t,
> msize=ms,
> ssize=ss,
> version=v }
> put _ = undefined