module Database.Redis.Protocol (Reply(..), reply, renderRequest) where
import Prelude hiding (error, take)
import Control.Applicative
import Data.Attoparsec (takeTill)
import Data.Attoparsec.Char8 hiding (takeTill)
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B
data Reply = SingleLine ByteString
| Error ByteString
| Integer Integer
| Bulk (Maybe ByteString)
| MultiBulk (Maybe [Reply])
deriving (Eq, Show)
renderRequest :: [ByteString] -> ByteString
renderRequest req = B.concat (argCnt:args)
where
argCnt = B.concat ["*", showBS (length req), crlf]
args = map renderArg req
renderArg :: ByteString -> ByteString
renderArg arg = B.concat ["$", argLen arg, crlf, arg, crlf]
where
argLen = showBS . B.length
showBS :: (Show a) => a -> ByteString
showBS = B.pack . show
crlf :: ByteString
crlf = "\r\n"
reply :: Parser Reply
reply = choice [singleLine, integer, bulk, multiBulk, error]
singleLine :: Parser Reply
singleLine = SingleLine <$> (char '+' *> takeTill isEndOfLine <* endOfLine)
error :: Parser Reply
error = Error <$> (char '-' *> takeTill isEndOfLine <* endOfLine)
integer :: Parser Reply
integer = Integer <$> (char ':' *> signed decimal <* endOfLine)
bulk :: Parser Reply
bulk = Bulk <$> do
len <- char '$' *> signed decimal <* endOfLine
if len < 0
then return Nothing
else Just <$> take len <* endOfLine
multiBulk :: Parser Reply
multiBulk = MultiBulk <$> do
len <- char '*' *> signed decimal <* endOfLine
if len < 0
then return Nothing
else Just <$> count len reply