git-annex/BackendTypes.hs
2010-10-14 02:52:17 -04:00

44 lines
1.1 KiB
Haskell

{- git-annex backend data types
-
- Mostly only backend implementations should need to import this.
-}
module BackendTypes where
import Control.Monad.State
import Data.String.Utils
import qualified GitRepo as Git
-- git-annex's runtime state type doesn't really belong here,
-- but it uses Backend, so has to be here to avoid a depends loop.
data AnnexState = AnnexState {
repo :: Git.Repo,
backends :: [Backend]
} deriving (Show)
-- git-annex's monad
type Annex = StateT AnnexState IO
-- annexed filenames are mapped into keys
data Key = Key String deriving (Eq)
-- show a key to convert it to a string
instance Show Key where
show (Key v) = v
-- this structure represents a key/value backend
data Backend = Backend {
-- name of this backend
name :: String,
-- converts a filename to a key
getKey :: FilePath -> Annex (Maybe Key),
-- stores a file's contents to a key
storeFileKey :: FilePath -> Key -> Annex Bool,
-- retrieves a key's contents to a file
retrieveKeyFile :: Key -> FilePath -> Annex Bool,
-- removes a key
removeKey :: Key -> Annex Bool
}
instance Show Backend where
show backend = "Backend { name =\"" ++ (name backend) ++ "\" }"