{- |

Module : $Header$

Description : description of undo and redo functions

Copyright : uni-bremen and DFKI

License : GPLv2 or higher

Maintainer : r.pascanu@jacobs-university.de

Stability : provisional

Portability : portable

CMDL.UnDoRedo contains the implementation of the undo and redo commads

-}

module CMDL.UndoRedo

( cUndo

, cRedo

) where

import Interfaces.History(redoOneStep, undoOneStep)

import Interfaces.Command(showCmd)

import Interfaces.DataTypes(IntHistory(undoList, redoList),

CmdHistory(command), IntState(i_hist))

import CMDL.DataTypesUtils(genMessage)

import CMDL.DataTypes(CmdlState(intState))

-- | Undoes the last command entered

cUndo :: CmdlState -> IO CmdlState

cUndo = cdo True

-- | Redoes the last undo command

cRedo :: CmdlState -> IO CmdlState

cRedo = cdo False

cdo :: Bool -> CmdlState -> IO CmdlState

cdo isUndo state =

let msg = (if isUndo then "un" else "re") ++ "do"

in case (if isUndo then undoList else redoList) . i_hist $ intState state of

[] -> return $ genMessage [] ("Nothing to " ++ msg) state

action : _ ->

do

nwIntState <- (if isUndo then undoOneStep else redoOneStep)

$ intState state

return . genMessage [] ("Action '"++ showCmd (command action)

++ "' is now " ++ msg ++ "ne")

$ state { intState = nwIntState }