-- | This module is designed to be imported qualified.
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE NoImplicitPrelude          #-}
module Language.Haskell.Names.LocalSymbolTable
  ( Table
  , empty
  , lookupValue
  , addValue
  ) where

import           Fay.Compiler.Prelude               hiding (empty)
import           Language.Haskell.Names.SyntaxUtils
import           Language.Haskell.Names.Types

import qualified Data.Map                           as Map
import           Language.Haskell.Exts

-- | Local symbol table — contains locally bound names
newtype Table = Table (Map.Map NameS SrcLoc)
  deriving Monoid

addValue :: SrcInfo l => Name l -> Table -> Table
addValue n (Table vs) =
  Table (Map.insert (nameToString n) (getPointLoc $ ann n) vs)

lookupValue :: QName l -> Table -> Either (Error l) SrcLoc
lookupValue qn@(UnQual _ n) (Table vs) =
  maybe (Left $ ENotInScope qn) Right $
    Map.lookup (nameToString n) vs
lookupValue qn _ = Left $ ENotInScope qn

empty :: Table
empty = Table Map.empty