69 lines
1.8 KiB
Haskell
69 lines
1.8 KiB
Haskell
{- git-annex backend data types
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-
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- Mostly only backend implementations should need to import this.
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-}
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module BackendTypes where
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import Control.Monad.State (StateT)
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import Data.String.Utils
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import qualified GitRepo as Git
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-- command-line flags
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data Flag = Force
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deriving (Eq, Read, Show)
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-- git-annex's runtime state type doesn't really belong here,
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-- but it uses Backend, so has to be here to avoid a depends loop.
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data AnnexState = AnnexState {
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repo :: Git.Repo,
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backends :: [Backend],
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flags :: [Flag]
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} deriving (Show)
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-- git-annex's monad
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type Annex = StateT AnnexState IO
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-- annexed filenames are mapped through a backend into keys
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type KeyFrag = String
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type BackendName = String
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data Key = Key (BackendName, KeyFrag) deriving (Eq)
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-- show a key to convert it to a string; the string includes the
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-- name of the backend to avoid collisions between key strings
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instance Show Key where
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show (Key (b, k)) = b ++ ":" ++ k
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instance Read Key where
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readsPrec _ s = [((Key (b,k)) ,"")]
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where
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l = split ":" s
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b = l !! 0
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k = join ":" $ drop 1 l
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-- pulls the backend name out
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backendName :: Key -> BackendName
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backendName (Key (b,k)) = b
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-- pulls the key fragment out
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keyFrag :: Key -> KeyFrag
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keyFrag (Key (b,k)) = k
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-- this structure represents a key/value backend
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data Backend = Backend {
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-- name of this backend
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name :: String,
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-- converts a filename to a key
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getKey :: FilePath -> Annex (Maybe Key),
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-- stores a file's contents to a key
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storeFileKey :: FilePath -> Key -> Annex Bool,
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-- retrieves a key's contents to a file
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retrieveKeyFile :: Key -> FilePath -> Annex Bool,
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-- removes a key
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removeKey :: Key -> Annex Bool,
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-- checks if a backend is storing the content of a key
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hasKey :: Key -> Annex Bool
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}
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instance Show Backend where
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show backend = "Backend { name =\"" ++ (name backend) ++ "\" }"
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