{- |

Module :$Header$

Description : The definition of file processing interface

Copyright : uni-bremen and DFKI

License : similar to LGPL, see HetCATS/LICENSE.txt or LIZENZ.txt

Maintainer : r.pascanu@jacobs-university.de

Stability : provisional

Portability : portable

CMDL.FileInterface describes the interface specific function

for file input

-}

module CMDL.FileInterface

( fileShellDescription

, fileBackend

, fileGetSingleChar

, fileGetInput

) where

import System.Console.Shell(CommandStyle(OnlyCommands), ShellDescription(..),

initialShellDescription)

import System.Console.Shell.Backend(ShellBackend(..))

import System.IO

import Control.Monad(when)

import CMDL.Commands(shellacCommands, shellacEvalFunc)

import CMDL.DataTypes(CMDL_State)

import CMDL.StdInterface(basicOutput)

import CMDL.Utils(stripComments)

import Common.Utils(trim)

import qualified Control.Exception as Ex

-- | Creates the Backend for reading from files

fileBackend :: String -> ShellBackend Handle

fileBackend filename = ShBackend

{ initBackend = openFile filename ReadMode

, shutdownBackend = hClose

, outputString = const basicOutput

, flushOutput = \_ -> hFlush stdout

, getSingleChar = fileGetSingleChar

, getInput = fileGetInput

, addHistory = \_ _ -> return ()

, setWordBreakChars = \_ _ -> return ()

, getWordBreakChars = \_ -> return

" \t\n\r\v`~!@#$%^&*()=[]{};\\\'\",<>"

, onCancel = \_ -> putStrLn "canceled...\n"

, setAttemptedCompletionFunction = \_ _ -> return ()

, setDefaultCompletionFunction = \_ _ -> return ()

, completeFilename = \_ _ -> return []

, completeUsername = \_ _ -> return []

, clearHistoryState = \_ -> return ()

, getMaxHistoryEntries = \_ -> return 0

, setMaxHistoryEntries = \_ _ -> return ()

, readHistory = \_ _ -> return ()

, writeHistory = \_ _ -> return ()

}

-- | Used to get one char from a file open for reading

fileGetSingleChar :: Handle -> String -> IO (Maybe Char)

fileGetSingleChar file _

= Ex.bracket (hGetBuffering file) (hSetBuffering file) $

\_ -> do

hSetBuffering file NoBuffering

c <- hGetChar file

putStrLn []

return (Just c)

-- | Used to get a line from a file open for reading

fileGetInput :: Handle -> String -> IO (Maybe String)

fileGetInput file _ = do

x <- hGetLine file

when (trim (stripComments x) /= "") (putStrLn $ "> " ++ x)

return (Just x)

fileShellDescription :: ShellDescription CMDL_State

fileShellDescription =

let wbc = "\t\n\r\v\\" in

initialShellDescription

{ shellCommands = shellacCommands

, commandStyle = OnlyCommands

, evaluateFunc = shellacEvalFunc

, wordBreakChars = wbc

, prompt = \_ -> return []

, historyFile = Nothing

}