lib/hs/src/Thrift/Transport.hs

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--   http://www.apache.org/licenses/LICENSE-2.0
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module Thrift.Transport
  ( Transport(..)
  , TransportExn(..)
  , TransportExnType(..)
  ) where

import Control.Monad ( when )
import Control.Exception ( Exception, throw )

import Data.Typeable ( Typeable )

import qualified Data.ByteString.Lazy.Char8 as LBS
import Data.Monoid

class Transport a where
    tIsOpen :: a -> IO Bool
    tClose  :: a -> IO ()
    tRead   :: a -> Int -> IO LBS.ByteString
    tWrite  :: a -> LBS.ByteString -> IO ()
    tFlush  :: a -> IO ()
    tReadAll :: a -> Int -> IO LBS.ByteString

    tReadAll a 0 = return mempty
    tReadAll a len = do
        result <- tRead a len
        let rlen = fromIntegral $ LBS.length result
        when (rlen == 0) (throw $ TransportExn "Cannot read. Remote side has closed." TE_UNKNOWN)
        if len <= rlen
            then return result
            else (result `mappend`) `fmap` (tReadAll a (len - rlen))

data TransportExn = TransportExn String TransportExnType
  deriving ( Show, Typeable )
instance Exception TransportExn

data TransportExnType
    = TE_UNKNOWN
    | TE_NOT_OPEN
    | TE_ALREADY_OPEN
    | TE_TIMED_OUT
    | TE_END_OF_FILE
      deriving ( Eq, Show, Typeable )