runParser :: (Parser a b) [a] -> (Either Error b, [a])
runParser (Parser f) i = f i
-
-instance + Error where
- (+) r1 r2 = r2 //TODO
instance Functor (Parser a) where
- fmap f m = liftM f m
+ fmap f m = liftM f m
instance Applicative (Parser a) where
- pure a = Parser \i -> (Right a, i)
- (<*>) sf p = ap sf p
+ pure a = Parser \i -> (Right a, i)
+ (<*>) sf p = ap sf p
instance Monad (Parser a) where
- bind p f = Parser \i -> case runParser p i of
- (Right r, rest) = runParser (f r) rest
- (Left e, _) = (Left e, i)
+ bind p f = Parser \i -> case runParser p i of
+ (Right r, rest) = runParser (f r) rest
+ (Left e, _) = (Left e, i)
instance Alternative (Parser a) where
- empty = Parser \i -> (Left $ Error "" , i)
- (<|>) p1 p2 = Parser \i -> case runParser p1 i of
- (Right r, rest) = (Right r, rest)
- (Left e1, rest) = case runParser p2 i of
- (Left e2, rest) = (Left $ e1+e2, i)
- (Right r, rest) = (Right r, rest)
-
-//Try the parser, if it fails decorate the error with Expected of the given String and position
+ empty = Parser \i -> (Left $ Error "" , i)
+ (<|>) p1 p2 = Parser \i -> case runParser p1 i of
+ (Right r, rest) = (Right r, rest)
+ (Left e1, rest) = case runParser p2 i of
+ (Left e2, rest) = (Left e2, i)
+ (Right r, rest) = (Right r, rest)
+
+//Try parser, if it fails decorate the error with the given String and position
(<?>) :: (Parser a b) Error -> Parser a b
(<?>) p e = Parser \i -> case runParser p i of
- (Left e1, rest) = (Left $ e1 + e, rest)
- (Right r, rest) = (Right r, rest)
+ (Left e1, rest) = (Left e, rest)
+ (Right r, rest) = (Right r, rest)
fail :: Parser a b
fail = empty
top :: Parser a a
top = Parser \i -> case i of
- [] = (Left $ Error "", [])
- [x:xs] = (Right x, xs)
+ [] = (Left $ Error "", [])
+ [x:xs] = (Right x, xs)
peek :: Parser a a
peek = Parser \i -> case i of
- [] = (Left $ Error "", [])
- [x:xs] = (Right x, [x:xs])
+ [] = (Left $ Error "", [])
+ [x:xs] = (Right x, [x:xs])
-//runs the left parser until the right parser succeeds. Returns the result of the left parser
-//Note: if the right parser consumes input then this input is lost!
-//If the left parser fails before the right parser succeeds the whole parser fails
(until) infix 2 :: (Parser a b) (Parser a c) -> Parser a [b]
(until) p guard = try $ until` p guard []
- where
- until` :: (Parser a b) (Parser a c) [b] -> Parser a [b]
- until` p guard acc = Parser \i -> case runParser guard i of
- (Right _, rest) = (Right acc, rest)
- (Left _, _) = case runParser p i of
- (Right r, rest) = runParser (until` p guard [r:acc]) rest
- (Left e, _) = (Left e, i)
- try :: (Parser a b) -> Parser a b
- try p = Parser \i -> case runParser p i of
- (Left e, _) = (Left e, i)
- (Right r, rest) = (Right r, rest)
-
+ where
+ until` :: (Parser a b) (Parser a c) [b] -> Parser a [b]
+ until` p guard acc = Parser \i -> case runParser guard i of
+ (Right _, rest) = (Right acc, rest)
+ (Left _, _) = case runParser p i of
+ (Right r, rest) = runParser (until` p guard [r:acc]) rest
+ (Left e, _) = (Left e, i)
+ try :: (Parser a b) -> Parser a b
+ try p = Parser \i -> case runParser p i of
+ (Left e, _) = (Left e, i)
+ (Right r, rest) = (Right r, rest)
eof :: Parser a Void
eof = Parser \i -> case i of
- [] = (Right Void, [])
- _ = (Left $ Error "", i)
+ [] = (Right Void, [])
+ _ = (Left $ Error "", i)
satisfy :: (a -> Bool) -> Parser a a
satisfy f = top >>= \r -> if (f r) (return r) fail