module Text.Trifecta.Diagnostic.Err.State 
  ( ErrState(..)
  ) where

import Data.Functor.Plus
import Data.Set as Set
import Data.Semigroup
import Data.Monoid
import Text.PrettyPrint.Free
import Text.Trifecta.Diagnostic.Err

data ErrState e = ErrState
 { errExpected  :: !(Set String)
 , errMessage   :: !(Err e)
 }

instance Functor ErrState where
  fmap f (ErrState a b) = ErrState a (fmap f b)

instance Alt ErrState where
  ErrState a b <!> ErrState a' b' = ErrState (a <> a') (b <> b')
  {-# INLINE (<!>) #-}

instance Plus ErrState where
  zero = ErrState mempty mempty
 
instance Semigroup (ErrState e) where
  (<>) = (<!>) 

instance Monoid (ErrState e) where
  mempty = zero
  mappend = (<!>)