{-# LANGUAGE OverloadedStrings #-}
module ShellWords
( parse
) where
import Data.Bifunctor (first)
import Data.Char
import Data.Maybe (fromMaybe)
import Data.Semigroup ((<>))
import Data.Text (Text)
import Data.Text as T
import Data.Void (Void)
import Text.Megaparsec hiding (parse)
import qualified Text.Megaparsec as Megaparsec
import Text.Megaparsec.Char
type Parser = Parsec Void Text
parse :: Text -> Either String [Text]
parse = first parseErrorPretty . Megaparsec.parse parser "<input>"
parser :: Parser [Text]
parser = shellword `sepBy` space1
shellword :: Parser Text
shellword = choice [quoted, shelloption, value]
quoted :: Parser Text
quoted = do
q <- oneOf ['\'', '\"']
T.pack <$> manyTill (try (escaped q) <|> anyToken) (char q)
shelloption :: Parser Text
shelloption = (<>)
<$> flag
<*> (fromMaybe "" <$> optional argument)
flag :: Parser Text
flag = (<>)
<$> (string "--" <|> string "-")
<*> (quoted <|> (T.pack <$> many (noneOf ['=', ' '])))
argument :: Parser Text
argument = (<>)
<$> (T.singleton <$> char '=')
<*> (quoted <|> value)
value :: Parser Text
value = T.pack <$> many (try (escaped ' ') <|> nonSpace)
escaped :: Char -> Parser Char
escaped c = c <$ string ("\\" <> T.singleton c)
anyToken :: Parser Char
anyToken = satisfy $ const True
nonSpace :: Parser Char
nonSpace = satisfy $ not . isSpace