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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(..),
AssociatedFile,
stubKey,
key2file,
file2key,
prop_idempotent_key_encode,
prop_idempotent_key_decode
) where
import System.Posix.Types
import Common
import Utility.QuickCheck
{- A Key has a unique name, which is derived from a particular backend,
- and may contain other optional metadata. -}
data Key = Key
{ keyName :: String
, keyBackendName :: String
, keySize :: Maybe Integer
, keyMtime :: Maybe EpochTime
} deriving (Eq, Ord, Read, Show)
{- A filename may be associated with a Key. -}
type AssociatedFile = Maybe FilePath
stubKey :: Key
stubKey = Key
{ keyName = ""
, keyBackendName = ""
, keySize = Nothing
, keyMtime = Nothing
}
fieldSep :: Char
fieldSep = '-'
{- Converts a key to a string that is suitable for use as a filename.
- The name field is always shown last, separated by doubled fieldSeps,
- and is the only field allowed to contain the fieldSep. -}
key2file :: Key -> FilePath
key2file 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
_ ?: _ = ""
file2key :: FilePath -> Maybe Key
file2key s
| key == Just stubKey || (keyName <$> key) == Just "" || (keyBackendName <$> key) == Just "" = Nothing
| otherwise = 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 = do
sz <- readish v
return $ k { keySize = Just sz }
addfield 'm' k v = do
mtime <- readish v
return $ k { keyMtime = Just mtime }
addfield _ _ _ = Nothing
instance Arbitrary Key where
arbitrary = Key
<$> (listOf1 $ elements $ ['A'..'Z'] ++ ['a'..'z'] ++ ['0'..'9'] ++ "-_\r\n \t")
<*> (listOf1 $ elements ['A'..'Z']) -- BACKEND
<*> ((abs <$>) <$> arbitrary) -- size cannot be negative
<*> arbitrary
prop_idempotent_key_encode :: Key -> Bool
prop_idempotent_key_encode k = Just k == (file2key . key2file) k
prop_idempotent_key_decode :: FilePath -> Bool
prop_idempotent_key_decode f
| normalfieldorder = maybe True (\k -> key2file k == f) (file2key f)
| otherwise = True
where
-- file2key will accept the fields in any order, so don't
-- try the test unless the fields are in the normal order
normalfieldorder = fields `isPrefixOf` "sm"
fields = map (f !!) $ filter (< length f) $ map succ $
elemIndices fieldSep f
|
