urbit/pkg/king/lib/Vere/Term/Logic.hs
Benjamin Summers ff273f0b72 Demuxed terminals now track terminal state instead of terminal history.
Before, terminal demuxing used unbounded memory, but now it just tracks
the line state and 20 lines of history.
2019-09-18 16:11:06 -07:00

137 lines
3.6 KiB
Haskell

module Vere.Term.Logic
( SpinnerCause(..), St, Ev(..), Ef(..)
, init
, step
, drawState
, fromTermEv
, toTermEv
) where
import UrbitPrelude hiding (init)
import Data.Sequence (Seq((:<|)))
import qualified Arvo
import qualified Vere.Term.API as Term
--------------------------------------------------------------------------------
data SpinnerCause = User | Event Text
deriving (Show)
type SpinnerState = Maybe SpinnerCause
{-
%line -- Output a line above the edit line.
%spin -- Set the spinner state.
%bell -- Ring a bell (no change to the state).
%draw -- Redraw the current line (no change to the state).
%move -- Move the cursor position.
%edit -- Set the edit line, moving the cursor to the end.
%more -- Write the edit line to history, and clear it.
-}
data Ev
= EvLine Text
| EvSpin SpinnerState
| EvMove Word
| EvBell
| EvDraw
| EvEdit Text
| EvMore
deriving (Show)
data Ef
= EfClear
| EfWrite Text
| EfShift Int
| EfRing
| EfSpin SpinnerState
deriving (Show)
data St = St
{ sHistory :: Seq Text
, sLine :: Text
, sCurPos :: Word
, sSpinner :: SpinnerState
}
deriving (Show)
--------------------------------------------------------------------------------
init :: St
init = St mempty "" 0 Nothing
{-
When we process `EvMore`, we need to append a newline to the end of
the current line. During normal play, the ENTER key inserts the
newline for us, so we need to recreate that newline when we rebuild
the state for a new terminal connection.
-}
step :: St -> Ev -> St
step st@St{..} = \case
EvLine t -> st & record t
EvSpin s -> st { sSpinner = s }
EvMove w -> st { sCurPos = min w (word $ length sLine) }
EvEdit t -> st { sLine = t, sCurPos = word (length t) }
EvMore -> st { sLine = "", sCurPos = 0 } & record (sLine <> "\n")
EvBell -> st
EvDraw -> st
where
word :: Integral i => i -> Word
word = fromIntegral
record :: Text -> St -> St
record t st@St{..} = st { sHistory = trim (sHistory |> t) }
trim :: Seq a -> Seq a
trim s | length s < 20 = s
trim (_ :<| s) = s
trim s = s
drawState :: St -> [Ev]
drawState St{..} = hist <> out <> cur <> spin
where
hist = EvLine <$> toList sHistory
out = if null sLine then [] else [EvEdit sLine]
cur = if 0 == sCurPos then [] else [EvMove $ fromIntegral $ sCurPos]
spin = maybe [] (singleton . EvSpin . Just) sSpinner
-- Conversion ------------------------------------------------------------------
fromBlit :: Arvo.Blit -> Maybe Ev
fromBlit = \case
Arvo.Hop w -> Just $ EvMove $ fromIntegral w
Arvo.Bel () -> Just EvBell
Arvo.Clr () -> Just EvDraw
Arvo.Lin s -> Just $ EvEdit (pack s)
Arvo.Mor () -> Just EvMore
_ -> Nothing
toCause :: Maybe Cord -> SpinnerCause
toCause Nothing = User
toCause (Just (Cord c)) = Event c
fromCause :: SpinnerCause -> Maybe Cord
fromCause User = Nothing
fromCause (Event t) = Just (Cord t)
fromTermEv :: Term.Ev -> [Ev]
fromTermEv = \case
Term.Blits bs -> catMaybes (fromBlit <$> bs)
Term.Trace t -> [EvLine $ unCord t]
Term.Blank -> [EvLine ""]
Term.Spinr s -> [EvSpin $ toCause <$> s]
toTermEv :: Ev -> Term.Ev
toTermEv = \case
EvLine "" -> Term.Blank
EvLine t -> Term.Trace (Cord t)
EvSpin s -> Term.Spinr (fromCause <$> s)
EvMove w -> Term.Blits [Arvo.Hop $ fromIntegral w]
EvBell -> Term.Blits [Arvo.Bel ()]
EvDraw -> Term.Blits [Arvo.Clr ()]
EvEdit t -> Term.Blits [Arvo.Lin $ unpack t]
EvMore -> Term.Blits [Arvo.Mor ()]