{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DeriveAnyClass #-}
module Frontend.Syntax.Var where

import qualified Data.Text as T
import Data.Text (Text)

import Development.Shake.Classes

import Frontend.Parser.Posn

import GHC.Generics (Generic)

data ParsedVar
  = UnqualVar
    { varId    :: Text
    , varBegin :: Posn
    , varEnd   :: Posn
    }
  | QualVar
    { varId     :: Text
    , varPrefix :: Text
    , varBegin  :: Posn
    , varEnd    :: Posn
    }
  | ModId
    { varId    :: Text
    , varBegin :: Posn
    , varEnd   :: Posn
    }
  | BuiltinId
    { varId      :: Text
    , varBuiltin :: BuiltinIdClass
    , varBegin   :: Posn
    , varEnd     :: Posn
    }
  deriving (Eq, Show, Generic, Binary, Hashable, NFData)

data BuiltinIdClass
  = BuiltinTuple !Int
  | BuiltinNil
  | BuiltinArrow
  deriving (Eq, Show, Generic, Binary, Hashable, NFData)

toModId :: ParsedVar -> ParsedVar
toModId x@ModId{}             = x
toModId (UnqualVar x y z)     = ModId x y z
toModId (QualVar id pref b e) = ModId (pref <> T.singleton '.' <> id) b e
toModId BuiltinId{} =
  error "Built-in variable can not be a module identifier!"

splitModuleIdentifier :: Text -> [Text]
splitModuleIdentifier t
  | T.null fst = []
  | otherwise  = fst:splitModuleIdentifier (T.drop 1 snd)
  where (fst, snd) = T.span (/= '.') t