{-
This module is part of Chatty.
Copyleft (c) 2014 Marvin Cohrs
All wrongs reversed. Sharing is an act of love, not crime.
Please share Antisplice with everyone you like.
Chatty is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Chatty is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with Chatty. If not, see .
-}
module Text.Chatty.Expansion.History where
import Prelude hiding (id,(.))
import Control.Arrow
import Control.Category (id,(.))
import Control.Monad
import Control.Monad.IO.Class
import Control.Monad.Trans.Class
import Text.Chatty.Expansion
newtype HistoryT m a = History {
runHistoryT :: [String] -> m (a,[String])
}
instance Monad m => Monad (HistoryT m) where
return a = History $ \s -> return (a,s)
(History h) >>= f = History $ \s -> do (a,s') <- h s; runHistoryT (f a) s'
instance MonadTrans HistoryT where
lift m = History $ \s -> do a <- m; return (a,s)
instance MonadIO m => MonadIO (HistoryT m) where
liftIO = lift . liftIO
instance Monad m => Functor (HistoryT m) where
fmap f a = History $ \s -> do (a',s') <- runHistoryT a s; return (f a',s')
class Monad he => ChHistoryEnv he where
mcounth :: he Int
mgeth :: Int -> he String
mputh :: String -> he ()
instance Monad m => ChHistoryEnv (HistoryT m) where
mcounth = History $ runKleisli (arr length &&& id)
mgeth i
| i <= 0 = let j = -i in History $ runKleisli (arr (!!j) &&& id)
| otherwise = History . runKleisli $ arr ((!!i).reverse &&& id)
mputh s = History . runKleisli $ arr (const () &&& (s:))
expandHist :: ChHistoryEnv h => String -> h String
expandHist [] = return []
expandHist ('!':ss) =
let (nm,rm) = (takeWhile isNum &&& dropWhile isNum) ss
isNum a = elem a ['0'..'9'] || (a=='-')
in case nm of
[] -> do
ss' <- expandHist ss
return ('!':ss')
_ -> do
hs <- expandHist rm
h <- mgeth $ read nm
return (h++hs)
expandHist (s:ss) = do ss' <- expandHist ss; return (s:ss')
instance ChExpand m => ChExpand (HistoryT m) where
expand = lift . expand <=< expandHist
withHistory :: Monad m => HistoryT m a -> m a
withHistory = liftM fst . flip runHistoryT []