{- |

Module :$Header$

Description : The definition of string 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

PGIP.StringInterface describes the interface specific function

for string input

-}

module PGIP.StringInterface

( stringShellDescription

, stringBackend

, stringGetSingleChar

, stringGetInput

) where

import System.Console.Shell

import System.Console.Shell.Backend

import System.IO

import PGIP.DataTypes

import PGIP.Commands

import Control.Concurrent.MVar

-- | Creates the Backend for reading from files

stringBackend :: String -> ShellBackend (MVar String)

stringBackend input = ShBackend

{ initBackend = newMVar input

, shutdownBackend = \_ -> return ()

, outputString = \_ -> \_ -> return ()

, flushOutput = \_ -> hFlush stdout

, getSingleChar = stringGetSingleChar

, getInput = stringGetInput

, addHistory = \_ _ -> return ()

, setWordBreakChars = \_ _ -> return ()

, getWordBreakChars = \_ -> return

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

, onCancel = \_ -> hPutStrLn stdout "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 string

stringGetSingleChar :: MVar String -> String -> IO (Maybe Char)

stringGetSingleChar st _

= do

str <- readMVar st

case str of

[] -> return Nothing

x:l -> do

swapMVar st l

return $ Just x

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

stringGetInput :: MVar String -> String -> IO (Maybe String)

stringGetInput st _

= do

str <-readMVar st

case lines str of

[] -> return Nothing

x:l -> do

swapMVar st $ unlines l

return $ Just x

stringShellDescription :: ShellDescription CMDL_State

stringShellDescription =

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

initialShellDescription

{ shellCommands = shellacCommands

, commandStyle = OnlyCommands

, evaluateFunc = shellacEvalFunc

, wordBreakChars = wbc

, prompt = \_ -> return []

, historyFile = Nothing

}