ref: 6deb7698801b1d644c9d3a8bc94cd22adc8490f5
dir: /src/Text/ParserComb.hs/
-- Copyright 2023 Lennart Augustsson
-- See LICENSE file for full license.
{-# OPTIONS_GHC -Wno-type-defaults #-}
module Text.ParserComb(
(>>=), (>>), pure,
(<*), (*>), (<*>), (<$), (<$>),
(<|>),
fail, guard,
get, put, modify,
Prsr, runPrsr,
satisfy, satisfyM, eof,
choice,
many, emany, optional, eoptional,
some, esome,
esepBy, sepBy1, esepBy1,
esepEndBy, esepEndBy1,
(<?>), (<|<),
--notFollowedBy,
lookAhead,
inject, nextToken,
LastFail(..),
) where
--Ximport Prelude()
import Prelude
import Control.Applicative
import Control.Monad
data LastFail t
= LastFail Int [t] [String]
--Xderiving (Show)
maxInt :: Int
maxInt = 1000000000
noFail :: forall t . LastFail t
noFail = LastFail maxInt [] []
longest :: forall t . LastFail t -> LastFail t -> LastFail t
longest lf1@(LastFail l1 t1 x1) lf2@(LastFail l2 _ x2) =
if l1 < l2 then
lf1
else if l2 < l1 then
lf2
else
LastFail l1 t1 (x1 ++ x2)
longests :: forall t . [LastFail t] -> LastFail t
longests xs = foldl1 longest xs
data Res s t a = Many [(a, ([t], s))] (LastFail t)
--deriving (Show)
data Prsr s t a = P (([t], s) -> Res s t a)
--instance Show (Prsr s t a) where show _ = "<<Prsr>>"
runP :: forall s t a . Prsr s t a -> (([t], s) -> Res s t a)
runP (P p) = p
instance forall s t . Functor (Prsr s t) where
fmap f p = P $ \ t ->
case runP p t of
Many aus lf -> Many [ (f a, u) | (a, u) <- aus ] lf
instance forall s t . Applicative (Prsr s t) where
pure a = P $ \ t -> Many [(a, t)] noFail
(<*>) = ap
(*>) p k = p >>= \ _ -> k
instance forall s t . Monad (Prsr s t) where
(>>=) p k = P $ \ t ->
case runP p t of
Many aus plf ->
let { xss = [ runP (k a) u | au <- aus, let { (a, u) = au } ] }
in case unzip [ (rs, lf) | xs <- xss, let { Many rs lf = xs } ] of
(rss, lfs) -> Many (concat rss) (longests (plf : lfs))
return = pure
instance forall s t . MonadFail (Prsr s t) where
fail m = P $ \ (ts, _) -> Many [] (LastFail (length ts) (take 1 ts) [m])
instance forall s t . Alternative (Prsr s t) where
empty = P $ \ (ts, _) -> Many [] (LastFail (length ts) (take 1 ts) [])
(<|>) p q = P $ \ t ->
case runP p t of
Many a lfa ->
case runP q t of
Many b lfb -> Many (a ++ b) (longest lfa lfb)
get :: forall s t . Prsr s t s
get = P $ \ t@(_, s) -> Many [(s, t)] noFail
put :: forall s t . s -> Prsr s t ()
put s = P $ \ (ts, _) -> Many [((), (ts, s))] noFail
modify :: forall s t . (s -> s) -> Prsr s t ()
modify f = get >>= \ s -> put (f s)
-- Left biased choice
infixl 3 <|<
(<|<) :: forall s t a . Prsr s t a -> Prsr s t a -> Prsr s t a
(<|<) p q = P $ \ t ->
case runP p t of
Many [] lfa ->
case runP q t of
Many b lfb -> Many b (longest lfa lfb)
r -> r
{-
many :: forall s t a . Prsr s t a -> Prsr s t [a]
many p = some p <|> pure []
some :: forall s t a . Prsr s t a -> Prsr s t [a]
some p = (:) <$> p <*> many p
-}
{-
optional :: forall s t a . Prsr s t a -> Prsr s t (Maybe a)
optional p = (Just <$> p) <|> pure Nothing
-}
emany :: forall s t a . Prsr s t a -> Prsr s t [a]
emany p = esome p <|< pure []
esome :: forall s t a . Prsr s t a -> Prsr s t [a]
esome p = (:) <$> p <*> emany p
eoptional :: forall s t a . Prsr s t a -> Prsr s t (Maybe a)
eoptional p = (Just <$> p) <|< pure Nothing
runPrsr :: forall s t a . --X(Show a, Show s) =>
s -> Prsr s t a -> [t] -> Either (LastFail t) [(a, s)]
runPrsr s (P p) f =
case p (f, s) of
Many [] lf -> Left lf
Many xs _ -> Right [(a, snd x) | (a, x) <- xs ]
choice :: forall s t a . [Prsr s t a] -> Prsr s t a
choice [] = empty
choice ps = foldr1 (<|>) ps
satisfy :: forall s t . String -> (t -> Bool) -> Prsr s t t
satisfy msg f = P $ \ (acs, s) ->
case acs of
c:cs | f c -> Many [(c, (cs, s))] noFail
_ -> Many [] (LastFail (length acs) (take 1 acs) [msg])
satisfyM :: forall s t a . String -> (t -> Maybe a) -> Prsr s t a
satisfyM msg f = P $ \ (acs, s) ->
case acs of
c:cs | Just a <- f c -> Many [(a, (cs, s))] noFail
_ -> Many [] (LastFail (length acs) (take 1 acs) [msg])
eof :: forall s t . Prsr s t ()
eof = P $ \ t@(cs, _) ->
if null cs then
Many [((), t)] noFail
else
Many [] (LastFail (length cs) (take 1 cs) ["eof"])
infixl 9 <?>
(<?>) :: forall s t a . Prsr s t a -> String -> Prsr s t a
(<?>) p e = P $ \ t ->
-- trace ("<?> " ++ show e) $
case runP p t of
Many rs (LastFail l ts _) ->
Many rs (LastFail l ts [e])
{-
notFollowedBy :: forall s t a . Prsr s t a -> Prsr s t ()
notFollowedBy p = P $ \ t@(ts,_) ->
case runP p t of
Many [] _ -> Many [((), t)] noFail
_ -> Many [] (LastFail (length ts) (take 1 ts) ["!"])
-}
lookAhead :: forall s t a . Prsr s t a -> Prsr s t ()
lookAhead p = P $ \ t ->
case runP p t of
Many [] (LastFail l ts xs) -> Many [] (LastFail l (take 1 ts) xs)
_ -> Many [((), t)] noFail
nextToken :: forall s t . Prsr s t t
nextToken = P $ \ t@(cs, _) ->
case cs of
[] -> Many [] (LastFail (length cs) [] ["!eof"])
c:_ -> Many [(c, t)] noFail
inject :: forall s t . [t] -> Prsr s t ()
inject s = P $ \ (cs, st) -> Many [((), (s ++ cs, st))] noFail
sepBy1 :: forall s t a sep . Prsr s t a -> Prsr s t sep -> Prsr s t [a]
sepBy1 p sep = (:) <$> p <*> many (sep *> p)
esepBy1 :: forall s t a sep . Prsr s t a -> Prsr s t sep -> Prsr s t [a]
esepBy1 p sep = (:) <$> p <*> emany (sep *> p)
esepBy :: forall s t a sep . Prsr s t a -> Prsr s t sep -> Prsr s t [a]
esepBy p sep = esepBy1 p sep <|< pure []
esepEndBy :: forall s t a sep . Prsr s t a -> Prsr s t sep -> Prsr s t [a]
esepEndBy p sep = esepEndBy1 p sep <|< pure []
esepEndBy1 :: forall s t a sep . Prsr s t a -> Prsr s t sep -> Prsr s t [a]
esepEndBy1 p sep = (:) <$> p <*> ((sep *> esepEndBy p sep) <|< pure [])