{-# LANGUAGE
    UnicodeSyntax
  #-}
-- |This is an auxiliary parser utilities. You usually don't have to
-- use this module directly.
module Network.HTTP.Lucu.Parser
    ( atMost
    , finishOff
    )
    where
import Control.Applicative
import Control.Applicative.Unicode
import Control.Monad.Unicode
import Data.Attoparsec
import Prelude.Unicode

-- |@'atMost' n v@ is like @'P.many' v@ but accumulates @v@ at most
-- @n@ times.
atMost ∷ Alternative f ⇒ Int → f α → f [α]
{-# INLINE atMost #-}
atMost 0 _ = pure []
atMost n v = ( (:) <$> v ⊛ atMost (n-1) v )
             <|>
             pure []

-- |@'finishOff' p@ is equivalent to @p '>>=' \\a -> 'endOfInput' '>>'
-- 'return' a@.
finishOff ∷ Parser α → Parser α
{-# INLINE finishOff #-}
finishOff = ((endOfInput *>) ∘ return =≪)