ToInterestBits64.hs

{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE FlexibleInstances     #-}
{-# LANGUAGE InstanceSigs          #-}
{-# LANGUAGE MultiParamTypeClasses #-}

module HaskellWorks.Data.Json.Internal.ToInterestBits64
  ( ToInterestBits64(..)
  ) where

import Control.Applicative
import Data.ByteString.Internal
import Data.Word
import HaskellWorks.Data.Json.Internal.MakeIndex

import qualified Data.ByteString                             as BS
import qualified Data.Vector.Storable                        as DVS
import qualified HaskellWorks.Data.Json.Internal.BlankedJson as J

class ToInterestBits64 a where
  toInterestBits64 :: a -> DVS.Vector Word64

instance ToInterestBits64 J.BlankedJson where
  toInterestBits64 bj = DVS.unsafeCast (DVS.unfoldrN newLen genInterestForever interestBS)
    where interestBS    = blankedJsonBssToInterestBitsBs (J.unBlankedJson bj)
          newLen        = (BS.length interestBS + 7) `div` 8 * 8

blankedJsonBssToInterestBitsBs :: [ByteString] -> ByteString
blankedJsonBssToInterestBitsBs bss = BS.concat $ blankedJsonToInterestBits bss

genInterestForever :: ByteString -> Maybe (Word8, ByteString)
genInterestForever bs = BS.uncons bs <|> Just (0, bs)