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author | 2011-01-26 00:37:50 -0400 | |
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committer | 2011-01-26 00:37:50 -0400 | |
commit | 616d1d4a208693c46f41781d9099c1f04ae067e6 (patch) | |
tree | 66e5fdfd24eb0f407ef491262e7798189e4821c2 /BackendTypes.hs | |
parent | aa2ca533bcef1848a9dc94bfea8d33a99e8f2df0 (diff) |
rename TypeInternals to BackendTypes
Now that it only contains types used by the backends
Diffstat (limited to 'BackendTypes.hs')
-rw-r--r-- | BackendTypes.hs | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/BackendTypes.hs b/BackendTypes.hs new file mode 100644 index 000000000..e4b155f98 --- /dev/null +++ b/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) |