47 lines
1.6 KiB
Haskell
47 lines
1.6 KiB
Haskell
-- | Miscellaneous general functions and Show, Eq, and Ord instances for PortID
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{-# LANGUAGE StandaloneDeriving #-}
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module Database.MongoDB.Internal.Util where
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import Prelude hiding (length)
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import Control.Applicative ((<$>))
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import Network (PortID(..))
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import Data.UString as U (cons, append)
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import Data.Bits (Bits, (.|.))
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import Data.Bson
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import Data.ByteString.Lazy as S (ByteString, length, append, hGet)
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import System.IO (Handle)
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import System.IO.Error (mkIOError, eofErrorType)
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import Control.Exception (assert)
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deriving instance Show PortID
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deriving instance Eq PortID
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deriving instance Ord PortID
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bitOr :: (Bits a) => [a] -> a
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-- ^ bit-or all numbers together
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bitOr = foldl (.|.) 0
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(<.>) :: UString -> UString -> UString
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-- ^ Concat first and second together with period in between. Eg. @\"hello\" \<.\> \"world\" = \"hello.world\"@
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a <.> b = U.append a (cons '.' b)
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true1 :: Label -> Document -> Bool
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-- ^ Is field's value a 1 or True (MongoDB use both Int and Bools for truth values). Error if field not in document or field not a Num or Bool.
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true1 k doc = case valueAt k doc of
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Bool b -> b
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Float n -> n == 1
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Int32 n -> n == 1
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Int64 n -> n == 1
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_ -> error $ "expected " ++ show k ++ " to be Num or Bool in " ++ show doc
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hGetN :: Handle -> Int -> IO ByteString
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-- ^ Read N bytes from hande, blocking until all N bytes are read. If EOF is reached before N bytes then raise EOF exception.
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hGetN h n = assert (n >= 0) $ do
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bytes <- hGet h n
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let x = fromEnum $ length bytes
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if x >= n then return bytes
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else if x == 0 then ioError (mkIOError eofErrorType "hGetN" (Just h) Nothing)
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else S.append bytes <$> hGetN h (n - x)
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