module Language.Elna.Parser
    ( Parser
    , programP
    ) where

import Control.Monad (void)
import Data.Text (Text)
import Data.Void (Void)
import Language.Elna.AST
    ( Statement(..)
    , Program(..)
    )
import Text.Megaparsec (Parsec)
import Text.Megaparsec.Char (space1)
import qualified Text.Megaparsec.Char.Lexer as Lexer

type Parser = Parsec Void Text

space :: Parser ()
space = Lexer.space space1 (Lexer.skipLineComment "//")
    $ Lexer.skipBlockComment "{" "}"

lexeme :: forall a. Parser a -> Parser a
lexeme = Lexer.lexeme space

symbol :: Text -> Parser Text
symbol = Lexer.symbol space

beginP :: Parser ()
beginP = void $ symbol "begin"

endP :: Parser ()
endP = void $ symbol  "end"

programP :: Parser Program
programP = beginP >> endP >> symbol "."
    >> pure (Program mempty $ CompoundStatement mempty)