rename TypeInternals to BackendTypes

Now that it only contains types used by the backends

BackendTypes.hs

@@ -0,0 +1,78 @@
+{- git-annex key/value backend data types
+ -
+ - Most things should not need this, using Types instead
+ -
+ - Copyright 2010 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module BackendTypes where
+
+import Data.String.Utils
+import Test.QuickCheck
+
+type KeyName = String
+type BackendName = String
+data Key = Key (BackendName, KeyName) deriving (Eq, Ord)
+
+data Backend a = Backend {
+	-- name of this backend
+	name :: String,
+	-- converts a filename to a key
+	getKey :: FilePath -> a (Maybe Key),
+	-- stores a file's contents to a key
+	storeFileKey :: FilePath -> Key -> a Bool,
+	-- retrieves a key's contents to a file
+	retrieveKeyFile :: Key -> FilePath -> a Bool,
+	-- removes a key, optionally checking that enough copies are stored
+	-- elsewhere
+	removeKey :: Key -> Maybe Int -> a Bool,
+	-- checks if a backend is storing the content of a key
+	hasKey :: Key -> a Bool,
+	-- called during fsck to check a key
+	-- (second parameter may be the number of copies that there should
+	-- be of the key)
+	fsckKey :: Key -> Maybe Int -> a Bool
+}
+
+instance Show (Backend a) where
+	show backend = "Backend { name =\"" ++ name backend ++ "\" }"
+
+instance Eq (Backend a) where
+	a == b = name a == name b
+
+-- accessors for the parts of a key
+keyName :: Key -> KeyName
+keyName (Key (_,k)) = k
+backendName :: Key -> BackendName
+backendName (Key (b,_)) = b
+
+-- constructs a key in a backend
+genKey :: Backend a -> KeyName -> Key
+genKey b f = Key (name b,f)
+
+-- show a key to convert it to a string; the string includes the
+-- name of the backend to avoid collisions between key strings
+instance Show Key where
+	show (Key (b, k)) = b ++ ":" ++ k
+
+instance Read Key where
+	readsPrec _ s = [(Key (b,k), "")]
+		where
+			l = split ":" s
+			b = if null l then "" else head l
+			k = join ":" $ drop 1 l
+
+-- for quickcheck
+instance Arbitrary Key where
+	arbitrary = do
+		backendname <- arbitrary
+		keyname <- arbitrary
+		return $ Key (backendname, keyname)
+
+prop_idempotent_key_read_show :: Key -> Bool
+prop_idempotent_key_read_show k
+	-- backend names will never contain colons
+	| elem ':' (backendName k) = True
+	| otherwise = k == (read $ show k)