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|
{- git-annex repository differences
-
- Copyright 2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Types.Difference (
Difference(..),
Differences(..),
readDifferences,
showDifferences,
getDifferences,
differenceConfigKey,
differenceConfigVal,
hasDifference,
listDifferences,
) where
import Utility.PartialPrelude
import qualified Git
import qualified Git.Config
import Data.Maybe
import Data.Monoid
import Prelude
import qualified Data.Set as S
-- Describes differences from the v5 repository format.
--
-- The serialization is stored in difference.log, so avoid changes that
-- would break compatability.
--
-- Not breaking compatability is why a list of Differences is used, rather
-- than a record type. With a record type, adding a new field for some future
-- difference would serialize to a value that an older version could not
-- parse, even if that new field was not used. With the Differences list,
-- old versions can still parse it, unless the new Difference constructor
-- is used.
--
-- The constructors intentionally do not have parameters; this is to
-- ensure that any Difference that can be expressed is supported.
-- So, a new repository version would be Version6, rather than Version Int.
data Difference
= ObjectHashLower
| OneLevelObjectHash
| OneLevelBranchHash
deriving (Show, Read, Eq, Ord, Enum, Bounded)
-- This type is used internally for efficient checking for differences,
-- but converted to S.Set Difference for serialization.
data Differences
= Differences
{ objectHashLower :: Bool
, oneLevelObjectHash :: Bool
, oneLevelBranchHash :: Bool
}
| UnknownDifferences
-- UnknownDifferences cannot be equal
instance Eq Differences where
UnknownDifferences == _ = False
_ == UnknownDifferences = False
a == b = all (\f -> f a == f b)
[ objectHashLower
, oneLevelObjectHash
, oneLevelBranchHash
]
instance Monoid Differences where
mempty = Differences False False False
mappend a@(Differences {}) b@(Differences {}) = a
{ objectHashLower = objectHashLower a || objectHashLower b
, oneLevelObjectHash = oneLevelObjectHash a || oneLevelObjectHash b
, oneLevelBranchHash = oneLevelBranchHash a || oneLevelBranchHash b
}
mappend _ _ = UnknownDifferences
readDifferences :: String -> Differences
readDifferences = maybe UnknownDifferences mkDifferences . readish
showDifferences :: Differences -> String
showDifferences = show . S.fromList . listDifferences
getDifferences :: Git.Repo -> Differences
getDifferences r = mkDifferences $ S.fromList $
mapMaybe getmaybe [minBound .. maxBound]
where
getmaybe d = case Git.Config.isTrue =<< Git.Config.getMaybe (differenceConfigKey d) r of
Just True -> Just d
_ -> Nothing
differenceConfigKey :: Difference -> String
differenceConfigKey ObjectHashLower = tunable "objecthashlower"
differenceConfigKey OneLevelObjectHash = tunable "objecthash1"
differenceConfigKey OneLevelBranchHash = tunable "branchhash1"
differenceConfigVal :: Difference -> String
differenceConfigVal _ = Git.Config.boolConfig True
tunable :: String -> String
tunable k = "annex.tune." ++ k
hasDifference :: Difference -> Differences -> Bool
hasDifference _ UnknownDifferences = False
hasDifference ObjectHashLower ds = objectHashLower ds
hasDifference OneLevelObjectHash ds = oneLevelObjectHash ds
hasDifference OneLevelBranchHash ds = oneLevelBranchHash ds
listDifferences :: Differences -> [Difference]
listDifferences d@(Differences {}) = map snd $
filter (\(f, _) -> f d)
[ (objectHashLower, ObjectHashLower)
, (oneLevelObjectHash, OneLevelObjectHash)
, (oneLevelBranchHash, OneLevelBranchHash)
]
listDifferences UnknownDifferences = []
mkDifferences :: S.Set Difference -> Differences
mkDifferences s = Differences
{ objectHashLower = check ObjectHashLower
, oneLevelObjectHash = check OneLevelObjectHash
, oneLevelBranchHash = check OneLevelBranchHash
}
where
check f = f `S.member` s
|
