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GHC/IO/Handle/Types.hs

module GHC.IO.Handle.Types (
      Handle(..), Handle__(..), showHandle,
      checkHandleInvariants,
      BufferList(..),
      HandleType(..),
      isReadableHandleType, isWritableHandleType, isReadWriteHandleType,
      BufferMode(..),
      BufferCodec(..),
      NewlineMode(..), Newline(..), nativeNewline,
      universalNewlineMode, noNewlineTranslation, nativeNewlineMode
  ) where

#undef DEBUG

import GHC.Base
import GHC.MVar
import GHC.IO
import GHC.IO.Buffer
import GHC.IO.BufferedIO
import GHC.IO.Encoding.Types
import GHC.IORef
import Data.Maybe
import GHC.Show
import GHC.Read
import GHC.Word
import GHC.IO.Device
import Data.Typeable
#ifdef DEBUG
import Control.Monad
#endif














































data Handle 
  = FileHandle                          
        FilePath                        
                                        
        !(MVar Handle__)

  | DuplexHandle                        
        FilePath                        
                                        
                                        
        !(MVar Handle__)                
        !(MVar Handle__)                

  deriving Typeable





instance Eq Handle where
 (FileHandle _ h1)     == (FileHandle _ h2)     = h1 == h2
 (DuplexHandle _ h1 _) == (DuplexHandle _ h2 _) = h1 == h2
 _ == _ = False 

data Handle__
  = forall dev enc_state dec_state . (IODevice dev, BufferedIO dev, Typeable dev) =>
    Handle__ {
      haDevice      :: !dev,
      haType        :: HandleType,           
      haByteBuffer  :: !(IORef (Buffer Word8)),
      haBufferMode  :: BufferMode,
      haLastDecode  :: !(IORef (dec_state, Buffer Word8)),
      haCharBuffer  :: !(IORef (Buffer CharBufElem)), 
      haBuffers     :: !(IORef (BufferList CharBufElem)),  
      haEncoder     :: Maybe (TextEncoder enc_state),
      haDecoder     :: Maybe (TextDecoder dec_state),
      haCodec       :: Maybe TextEncoding,
      haInputNL     :: Newline,
      haOutputNL    :: Newline,
      haOtherSide   :: Maybe (MVar Handle__) 
                                             
    }
    deriving Typeable




data BufferList e
  = BufferListNil 
  | BufferListCons (RawBuffer e) (BufferList e)




data HandleType
 = ClosedHandle
 | SemiClosedHandle
 | ReadHandle
 | WriteHandle
 | AppendHandle
 | ReadWriteHandle

isReadableHandleType :: HandleType -> Bool
isReadableHandleType ReadHandle         = True
isReadableHandleType ReadWriteHandle    = True
isReadableHandleType _                  = False

isWritableHandleType :: HandleType -> Bool
isWritableHandleType AppendHandle    = True
isWritableHandleType WriteHandle     = True
isWritableHandleType ReadWriteHandle = True
isWritableHandleType _               = False

isReadWriteHandleType :: HandleType -> Bool
isReadWriteHandleType ReadWriteHandle{} = True
isReadWriteHandleType _                 = False









checkHandleInvariants :: Handle__ -> IO ()
#ifdef DEBUG
checkHandleInvariants h_ = do
 bbuf <- readIORef (haByteBuffer h_)
 checkBuffer bbuf
 cbuf <- readIORef (haCharBuffer h_)
 checkBuffer cbuf
 when (isWriteBuffer cbuf && not (isEmptyBuffer cbuf)) $
   error ("checkHandleInvariants: char write buffer non-empty: " ++
          summaryBuffer bbuf ++ ", " ++ summaryBuffer cbuf)
 when (isWriteBuffer bbuf /= isWriteBuffer cbuf) $
   error ("checkHandleInvariants: buffer modes differ: " ++
          summaryBuffer bbuf ++ ", " ++ summaryBuffer cbuf)

#else
checkHandleInvariants _ = return ()
#endif












































data BufferMode  
 = NoBuffering  
 | LineBuffering
                
 | BlockBuffering (Maybe Int)
                
                
                
   deriving (Eq, Ord, Read, Show)







data Newline = LF    
             | CRLF  
             deriving (Eq, Ord, Read, Show)






data NewlineMode 
  = NewlineMode { inputNL :: Newline,
                    
                  outputNL :: Newline
                    
                 }
             deriving (Eq, Ord, Read, Show)



nativeNewline :: Newline
#ifdef mingw32_HOST_OS
nativeNewline = CRLF
#else
nativeNewline = LF
#endif









universalNewlineMode :: NewlineMode
universalNewlineMode  = NewlineMode { inputNL  = CRLF, 
                                      outputNL = nativeNewline }






nativeNewlineMode    :: NewlineMode
nativeNewlineMode     = NewlineMode { inputNL  = nativeNewline, 
                                      outputNL = nativeNewline }





noNewlineTranslation :: NewlineMode
noNewlineTranslation  = NewlineMode { inputNL  = LF, outputNL = LF }








instance Show HandleType where
  showsPrec _ t =
    case t of
      ClosedHandle      -> showString "closed"
      SemiClosedHandle  -> showString "semi-closed"
      ReadHandle        -> showString "readable"
      WriteHandle       -> showString "writable"
      AppendHandle      -> showString "writable (append)"
      ReadWriteHandle   -> showString "read-writable"

instance Show Handle where 
  showsPrec _ (FileHandle   file _)   = showHandle file
  showsPrec _ (DuplexHandle file _ _) = showHandle file

showHandle :: FilePath -> String -> String
showHandle file = showString "{handle: " . showString file . showString "}"

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