git-annex/RemoteClass.hs

46 lines
1.2 KiB
Haskell

{- git-annex remotes class
-
- Most things should not need this, using Remote instead
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module RemoteClass where
import Control.Exception
import Key
data Remote a = Remote {
-- each Remote has a unique uuid
uuid :: String,
-- each Remote has a human visible name
name :: String,
-- Remotes have a use cost; higher is more expensive
cost :: Int,
-- Transfers a key to the remote.
storeKey :: Key -> a Bool,
-- retrieves a key's contents to a file
retrieveKeyFile :: Key -> FilePath -> a Bool,
-- removes a key's contents
removeKey :: Key -> a Bool,
-- Checks if a key is present in the remote; if the remote
-- cannot be accessed returns a Left error.
hasKey :: Key -> a (Either IOException Bool),
-- Some remotes can check hasKey without an expensive network
-- operation.
hasKeyCheap :: Bool
}
instance Show (Remote a) where
show remote = "Remote { uuid =\"" ++ uuid remote ++ "\" }"
-- two remotes are the same if they have the same uuid
instance Eq (Remote a) where
x == y = uuid x == uuid y
-- order remotes by cost
instance Ord (Remote a) where
compare x y = compare (cost x) (cost y)