content: --
  -- Licensed to the Apache Software Foundation (ASF) under one
  -- or more contributor license agreements. See the NOTICE file
  -- distributed with this work for additional information
  -- regarding copyright ownership. The ASF licenses this file
  -- to you under the Apache License, Version 2.0 (the
  -- "License"); you may not use this file except in compliance
  -- with the License. You may obtain a copy of the License at
  --
  --   http://www.apache.org/licenses/LICENSE-2.0
  --
  -- Unless required by applicable law or agreed to in writing,
  -- software distributed under the License is distributed on an
  -- "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  -- KIND, either express or implied. See the License for the
  -- specific language governing permissions and limitations
  -- under the License.
  --
  
  module Thrift.Transport.IOBuffer
         ( WriteBuffer
         , newWriteBuffer
         , writeBuf
         , flushBuf
         , ReadBuffer
         , newReadBuffer
         , fillBuf
         , readBuf
         , peekBuf
         ) where
  
  import Data.ByteString.Lazy.Builder
  import Data.Functor
  import Data.IORef
  import Data.Monoid
  import Data.Word
  
  import qualified Data.ByteString.Lazy as LBS
  
  type WriteBuffer = IORef Builder
  type ReadBuffer = IORef LBS.ByteString
  
  newWriteBuffer :: IO WriteBuffer
  newWriteBuffer = newIORef mempty
  
  writeBuf :: WriteBuffer -> LBS.ByteString -> IO ()
  writeBuf w s = modifyIORef w ( <> lazyByteString s)
  
  flushBuf :: WriteBuffer -> IO LBS.ByteString
  flushBuf w = do
    buf <- readIORef w
    writeIORef w mempty
    return $ toLazyByteString buf
  
  newReadBuffer :: IO ReadBuffer
  newReadBuffer = newIORef mempty
  
  fillBuf :: ReadBuffer -> LBS.ByteString -> IO ()
  fillBuf = writeIORef
  
  readBuf :: ReadBuffer -> Int -> IO LBS.ByteString
  readBuf r n = do
    bs <- readIORef r
    let (hd, tl) = LBS.splitAt (fromIntegral n) bs
    writeIORef r tl
    return hd
  
  peekBuf :: ReadBuffer -> IO (Maybe Word8)
  peekBuf r = (fmap fst . LBS.uncons) <$> readIORef r
  