{-# LANGUAGE FlexibleContexts #-}

module Language.SimpleShell.Parser.Name
  ( nameP
  , keyword
  )
where


import Language.SimpleShell.Parser.Common.Lexeme (lexeme)

import Control.Monad (void)
import Data.Text (Text, cons)
import Data.Char (isAlpha, isAlphaNum)
import Text.Megaparsec (MonadParsec, takeWhileP, satisfy, notFollowedBy, try)
import Text.Megaparsec.Char (string)


isNameStartChar :: Char -> Bool
isNameStartChar c = isAlpha c || c == '_'

isNameChar :: Char -> Bool
isNameChar c = isAlphaNum c || c == '_'


nameP :: (MonadParsec e Text m) => m Text
nameP =
  lexeme $ cons <$> satisfy isNameStartChar <*> takeWhileP Nothing isNameChar


keyword :: (MonadParsec e Text m) => Text -> m ()
keyword kw =
  void $ lexeme $ try $ string kw <* notFollowedBy (satisfy isNameChar)