{-# LANGUAGE TemplateHaskell #-}

-- | QuasiQuoter for non-interpolated strings, texts and bytestrings.
--
-- The "s" quoter contains a multi-line string with no interpolation at all,
-- except that the leading newline is trimmed and carriage returns stripped.
--
-- @
-- {-\# LANGUAGE QuasiQuotes #-}
-- import Data.Text (Text)
-- import Data.String.QQ
-- foo :: Text -- "String", "ByteString" etc also works
-- foo = [s|
-- Well here is a
--     multi-line string!
-- |]
-- @
--
-- Any instance of the IsString type is permitted.
--
-- (For GHC versions 6, write "[$s||]" instead of "[s||]".)
--
module GHCup.Utils.String.QQ
  ( s
  )
where


import           Data.Char
import           GHC.Exts                       ( IsString(..) )
import           Language.Haskell.TH.Quote

-- | QuasiQuoter for a non-interpolating ASCII IsString literal.
-- The pattern portion is undefined.
s :: QuasiQuoter
s = QuasiQuoter
  (\s' -> case and $ fmap isAscii s' of
    True  -> (\a -> [|fromString a|]) . trimLeadingNewline . removeCRs $ s'
    False -> fail "Not ascii"
  )
  (error "Cannot use q as a pattern")
  (error "Cannot use q as a type")
  (error "Cannot use q as a dec")
 where
  removeCRs = filter (/= '\r')
  trimLeadingNewline ('\n' : xs) = xs
  trimLeadingNewline xs          = xs