1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci{- ---------------------------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci A LIBRARY OF MONADIC PARSER COMBINATORS

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci 29th July 1996

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci Revised, October 1996

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci Graham Hutton Erik Meijer

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci University of Nottingham University of Utrecht

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciThis Haskell 1.4 script defines a library of parser combinators, and is taken

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccifrom sections 1-6 of our article "Monadic Parser Combinators". Some changes

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccito the library have been made in the move from Gofer to Haskell:

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci * Do notation is used in place of monad comprehension notation;

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci * The parser datatype is defined using "newtype", to avoid the overhead

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci of tagging and untagging parsers with the P constructor.

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-----------------------------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciAdded to April 1997, for offside rule, block comments, annotations,

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciextra characters in identifiers .. -

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciextra combinator parsers for skipping over input -}

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimodule ParseLib2

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (Parser, item, papply, (+++), sat, many, many1, sepby, sepby1, chainl,

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci chainl1, chainr, chainr1, ops, bracket, char, digit, lower, upper,

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci letter, alphanum, string, ident, nat, int, spaces, comment, junk,

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci parse, token, natural, integer, symbol, identifier,

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci many1_offside, many_offside, off,

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci opt, skipUntil, skipUntilOff, skipUntilParse, skipNest) where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciimport Data.Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciimport Control.Monad

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciinfixr 5 +++

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- * The parser monad ---------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccinewtype Parser a = P (Pos -> Pstring -> [(a, Pstring)])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccitype Pstring = (Pos, String)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccitype Pos = (Int, Int)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciinstance Functor Parser where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci -- fmap :: (a -> b) -> (Parser a -> Parser b)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci fmap f (P p) = P (\ pos inp -> [(f v, out) | (v, out) <- p pos inp])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciinstance Monad Parser where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci -- return :: a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return v = P (\ _ inp -> [(v, inp)])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci -- >>= :: Parser a -> (a -> Parser b) -> Parser b

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (P p) >>= f = P (\ pos inp -> concat [papply (f v) pos out

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci | (v, out) <- p pos inp])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci fail _ = P (\ _ _ -> [])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciinstance MonadPlus Parser where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci -- mzero :: Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci mzero = P (\ _ _ -> [])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci -- mplus :: Parser a -> Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (P p) `mplus` (P q) = P (\ pos inp -> (p pos inp ++ q pos inp))

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- bits which donn't fit into Haskell's type classes just yet :-(

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccienv :: Parser Pos

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccienv = P (\ pos inp -> [(pos, inp)])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisetenv :: Pos -> Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisetenv s (P m) = P $ \ _ -> m s

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciupdate :: (Pstring -> Pstring) -> Parser Pstring

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciupdate f = P ( \ _ s -> [(s, f s)])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccifetch :: Parser Pstring

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccifetch = update id

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- * Other primitive parser combinators ---------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciitem :: Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciitem = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (pos, x : _) <- update newstate

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci defpos <- env

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci if onside pos defpos then return x else mzero

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccifirst :: Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccifirst (P p) = P (\ pos inp -> case p pos inp of

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci [] -> []

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x : _ -> [x])

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccipapply :: Parser a -> Pos -> Pstring -> [(a, Pstring)]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccipapply (P p) = p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- layout handling functions

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccionside :: Pos -> Pos -> Bool

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccionside (l, c) (dl, dc) = (c > dc) || (l == dl)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccinewstate :: Pstring -> Pstring

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccinewstate i@((l, c), xxs) = case xxs of

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci [] -> i

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x : xs -> ((l', c'), xs)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (l', c') = case x of

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci '\n' -> (l + 1, 0)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci '\t' -> (l, ((c `div` 8) + 1) * 8)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci _ -> (l, c + 1)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- * Derived combinators ------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci(+++) :: Parser a -> Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccip +++ q = first (p `mplus` q)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisat :: (Char -> Bool) -> Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisat p = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x <- item

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci if p x then return x else mzero

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany :: Parser a -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany p = many1 p +++ return []

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany1 :: Parser a -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany1 p = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x <- p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci xs <- many p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (x : xs)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisepby :: Parser a -> Parser b -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisepby p sep = sepby1 p sep +++ return []

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisepby1 :: Parser a -> Parser b -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisepby1 p sep = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x <- p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci xs <- many (sep >> p)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (x : xs)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainl :: Parser a -> Parser (a -> a -> a) -> a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainl p op v = chainl1 p op +++ return v

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainl1 :: Parser a -> Parser (a -> a -> a) -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainl1 p op = p >>= rest

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci rest x = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci f <- op

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci y <- p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci rest (f x y)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci +++ return x

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainr :: Parser a -> Parser (a -> a -> a) -> a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainr p op v = chainr1 p op +++ return v

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainr1 :: Parser a -> Parser (a -> a -> a) -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichainr1 p op = p >>= rest

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci rest x = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci f <- op

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci y <- p `chainr1` op

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (f x y)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci +++ return x

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciops :: [(Parser a, b)] -> Parser b

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciops xs = foldr1 (+++) [p >> return op | (p, op) <- xs]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccibracket :: Parser a -> Parser b -> Parser c -> Parser b

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccibracket open p close = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci open

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x <- p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci close

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return x

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- * Useful parsers -----------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichar :: Char -> Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccichar x = sat (x ==)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccidigit :: Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccidigit = sat isDigit

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccilower :: Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccilower = sat isLower

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciupper :: Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciupper = sat isUpper

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciletter :: Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciletter = sat isAlpha

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccialphanum :: Parser Char

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccialphanum = sat (\ x -> isAlphaNum x || x `elem` "'_.#")

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccistring :: String -> Parser String

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccistring "" = return ""

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccistring (x : xs) = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci char x

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci string xs

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (x : xs)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciident :: Parser String

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciident = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x <- lower

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci xs <- many alphanum

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (x : xs)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccinat :: Parser Int

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccinat = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x <- digit

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (digitToInt x)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci `chainl1` return op

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci where

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci m `op` n = 10 * m + n

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciint :: Parser Int

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciint = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci char '-'

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci n <- nat

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (-n)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci +++ nat

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- * Lexical combinators ------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccispaces :: Parser ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccispaces = many1 (sat isJunk) >> return ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciisJunk :: Char -> Bool

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciisJunk x = isSpace x || (not . isPrint) x || isControl x

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccicomment :: Parser ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccicomment = onelinecomment `mplus` bracecomment

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccionelinecomment :: Parser ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccionelinecomment = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci string "--"

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci many (sat (/= '\n'))

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccibracecomment :: Parser ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccibracecomment = skipNest

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (string "{-" >> sat (`notElem` "!@*"))

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (sat (`notElem` "!@*") >> string "-}")

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccijunk :: Parser ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccijunk = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci _ <- setenv (0, -1) (many (spaces +++ comment))

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciparse :: Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciparse = (junk >>)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccitoken :: Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccitoken p = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci v <- p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci junk

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return v

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- * Token parsers ------------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccinatural :: Parser Int

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccinatural = token nat

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciinteger :: Parser Int

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciinteger = token int

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisymbol :: String -> Parser String

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccisymbol xs = token (string xs)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciidentifier :: [String] -> Parser String

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciidentifier ks = token $ do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x <- ident

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci if notElem x ks then return x else mzero

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- * Offside Parsers ---------------------------------------------------------

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany1_offside :: Parser a -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany1_offside p = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (pos, _) <- fetch

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci setenv pos (many1 (off p))

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany_offside :: Parser a -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccimany_offside p = many1_offside p +++ mzero

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccioff :: Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccioff p = do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci (_, dc) <- env

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci ((l, c), _) <- fetch

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci if c == dc then setenv (l, dc) p else mzero

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci-- Noel's own favourite parsers

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipUntil :: Parser a -> Parser a

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipUntil p = p +++ do

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci token (many1 (sat (not . isSpace)))

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci skipUntil p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipNest :: Parser a -> Parser b -> Parser ()

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipNest start finish = let

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci x = (finish >> return ())

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci +++ (skipNest start finish >> x) +++ (item >> x)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci in start >> x

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci{- this are messy, but make writing incomplete parsers a whole lot

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccieasier. -}

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipUntilOff :: Parser a -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipUntilOff p = fmap (concatMap justs) . many_offside $

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci fmap Just p +++ fmap (const Nothing) (many1 (token (many1 item)))

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipUntilParse :: Char -> Parser a -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciskipUntilParse u p = fmap (concatMap justs) . many $

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci do r <- p

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci token (char u)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return (Just r)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci +++

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci do many . token . many1 . sat $ (/= u)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci token (char u)

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci return Nothing

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccijusts :: Maybe t -> [t]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccijusts (Just a) = [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgolluccijusts Nothing = []

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciopt :: Parser [a] -> Parser [a]

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucciopt p = p +++ return []

1e5905d1f04191cad9dae6117e1508c7f7d5587apgollucci