module Megaparsec (runSexp, runLongws, runNumcsv) where

import Control.Applicative
import qualified Data.ByteString as B
import Text.Megaparsec
import Data.Char

type Parser = Parsec () B.ByteString

isLatinLetter :: Char -> Bool
isLatinLetter c = ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z')

char8 :: Char -> Parser ()
char8 c = () <$ single (fromIntegral (ord c))

satisfy8 :: (Char -> Bool) -> Parser ()
satisfy8 f = () <$ satisfy (f . chr . fromIntegral)

ws      = skipMany (satisfy8 \c -> c == ' ' || c == '\n')
open    = char8 '(' >> ws
close   = char8 ')' >> ws
ident   = skipSome (satisfy8 isLatinLetter) <* ws
sexp    = (open *> skipSome sexp <* close) <|> ident
runSexp = runParser sexp ""

longw     = chunk "thisisalongkeyword"
longws    = skipSome (longw *> ws) <* eof
runLongws = runParser longws ""

numeral   = skipSome (satisfy8 \c -> '0' <= c && c <= '9') >> ws
comma     = single (fromIntegral (ord ',')) >> ws
numcsv    = numeral >> skipSome (comma >> numeral) >> eof
runNumcsv = runParser numcsv ""