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|
{- git-annex Key data type
-
- Most things should not need this, using Types instead
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Types.Key (
Key(..),
stubKey,
readKey,
prop_idempotent_key_read_show
) where
import System.Posix.Types
import Common
{- A Key has a unique name, is associated with a key/value backend,
- and may contain other optional metadata. -}
data Key = Key {
keyName :: String,
keyBackendName :: String,
keySize :: Maybe Integer,
keyMtime :: Maybe EpochTime
} deriving (Eq, Ord)
stubKey :: Key
stubKey = Key {
keyName = "",
keyBackendName = "",
keySize = Nothing,
keyMtime = Nothing
}
fieldSep :: Char
fieldSep = '-'
{- Keys show as strings that are suitable for use as filenames.
- The name field is always shown last, separated by doubled fieldSeps,
- and is the only field allowed to contain the fieldSep. -}
instance Show Key where
show Key { keyBackendName = b, keySize = s, keyMtime = m, keyName = n } =
b +++ ('s' ?: s) +++ ('m' ?: m) +++ (fieldSep : n)
where
"" +++ y = y
x +++ "" = x
x +++ y = x ++ fieldSep:y
c ?: (Just v) = c : show v
_ ?: _ = ""
readKey :: String -> Maybe Key
readKey s = if key == Just stubKey then Nothing else key
where
key = startbackend stubKey s
startbackend k v = sepfield k v addbackend
sepfield k v a = case span (/= fieldSep) v of
(v', _:r) -> findfields r $ a k v'
_ -> Nothing
findfields (c:v) (Just k)
| c == fieldSep = Just $ k { keyName = v }
| otherwise = sepfield k v $ addfield c
findfields _ v = v
addbackend k v = Just k { keyBackendName = v }
addfield 's' k v = Just k { keySize = readMaybe v }
addfield 'm' k v = Just k { keyMtime = readMaybe v }
addfield _ _ _ = Nothing
prop_idempotent_key_read_show :: Key -> Bool
prop_idempotent_key_read_show k = Just k == (readKey . show) k
|
