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{- git-annex general metadata
-
- Copyright 2014 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Types.MetaData (
MetaData,
MetaField,
MetaValue,
CurrentlySet(..),
MetaSerializable,
toMetaField,
fromMetaField,
toMetaValue,
mkMetaValue,
unsetMetaValue,
fromMetaValue,
fromMetaData,
newMetaData,
updateMetaData,
unionMetaData,
hasUniqueMetaData,
currentMetaData,
currentMetaDataValues,
getAllMetaData,
serialize,
deserialize,
prop_updateMetaData_sane,
prop_metadata_serialize
) where
import Common
import Utility.Base64
import Utility.QuickCheck
import qualified Data.Set as S
import qualified Data.Map as M
import Data.Char
newtype MetaData = MetaData (M.Map MetaField (S.Set MetaValue))
deriving (Show, Eq, Ord)
{- A metadata value can be currently be set (True), or may have been
- set before and we're remembering it no longer is (False). -}
newtype CurrentlySet = CurrentlySet Bool
deriving (Show, Eq, Ord, Arbitrary)
newtype MetaField = MetaField String
deriving (Show, Eq, Ord)
data MetaValue = MetaValue CurrentlySet String
deriving (Show, Ord)
{- Metadata values are compared equal whether currently set or not. -}
instance Eq MetaValue where
MetaValue _ a == MetaValue _ b = a == b
{- MetaData is serialized to a format like:
-
- field1 +val1 +val2 -val3 field2 +val4 +val5
-}
class MetaSerializable v where
serialize :: v -> String
deserialize :: String -> Maybe v
instance MetaSerializable MetaData where
serialize (MetaData m) = unwords $ concatMap go $ M.toList m
where
go (f, vs) = serialize f : map serialize (S.toList vs)
deserialize = Just . getfield newMetaData . words
where
getfield m [] = m
getfield m (w:ws) = maybe m (getvalues m ws) (deserialize w)
getvalues m [] _ = m
getvalues m l@(w:ws) f = case deserialize w of
Just v -> getvalues (updateMetaData f v m) ws f
Nothing -> getfield m l
instance MetaSerializable MetaField where
serialize (MetaField f) = f
deserialize = Just . MetaField
{- Base64 problimatic values. -}
instance MetaSerializable MetaValue where
serialize (MetaValue isset v) =
serialize isset ++
if any isSpace v || "!" `isPrefixOf` v
then '!' : toB64 v
else v
deserialize (isset:'!':v) = MetaValue
<$> deserialize [isset]
<*> fromB64Maybe v
deserialize (isset:v) = MetaValue
<$> deserialize [isset]
<*> pure v
deserialize [] = Nothing
instance MetaSerializable CurrentlySet where
serialize (CurrentlySet True) = "+"
serialize (CurrentlySet False) = "-"
deserialize "+" = Just (CurrentlySet True)
deserialize "-" = Just (CurrentlySet False)
deserialize _ = Nothing
{- Fields cannot be empty, contain whitespace, or start with "+-" as
- that would break the serialization. -}
toMetaField :: String -> Maybe MetaField
toMetaField f
| legalField f = Just $ MetaField f
| otherwise = Nothing
legalField :: String -> Bool
legalField f
| null f = False
| any isSpace f = False
| any (`isPrefixOf` f) ["+", "-"] = False
| otherwise = True
toMetaValue :: String -> MetaValue
toMetaValue = MetaValue (CurrentlySet True)
mkMetaValue :: CurrentlySet -> String -> MetaValue
mkMetaValue = MetaValue
unsetMetaValue :: MetaValue -> MetaValue
unsetMetaValue (MetaValue _ s) = MetaValue (CurrentlySet False) s
fromMetaField :: MetaField -> String
fromMetaField (MetaField f) = f
fromMetaValue :: MetaValue -> String
fromMetaValue (MetaValue _ f) = f
fromMetaData :: MetaData -> [(MetaField, S.Set MetaValue)]
fromMetaData (MetaData m) = M.toList m
newMetaData :: MetaData
newMetaData = MetaData M.empty
{- Can be used to set a value, or to unset it, depending on whether
- the MetaValue has CurrentlySet or not. -}
updateMetaData :: MetaField -> MetaValue -> MetaData -> MetaData
updateMetaData f v (MetaData m) = MetaData $
M.insertWith' S.union f (S.singleton v) m
{- New metadata overrides old._-}
unionMetaData :: MetaData -> MetaData -> MetaData
unionMetaData (MetaData old) (MetaData new) = MetaData $
M.unionWith S.union new old
{- Checks if m contains any fields with values that are not
- the same in comparewith. Note that unset and set values are
- considered to be the same, so if m sets a value and comparewith
- unsets it, m is not unique. However, if m changes the value,
- or adds a new value, it is unique. -}
hasUniqueMetaData :: MetaData -> MetaData -> Bool
hasUniqueMetaData (MetaData comparewith) (MetaData m) =
any uniquefield (M.toList m)
where
uniquefield :: (MetaField, S.Set MetaValue) -> Bool
uniquefield (f, v) = maybe True (uniquevalue v) (M.lookup f comparewith)
uniquevalue v1 v2 = not $ S.null $ S.difference v1 v2
isSet :: MetaValue -> Bool
isSet (MetaValue (CurrentlySet isset) _) = isset
{- Gets only currently set values -}
currentMetaDataValues :: MetaField -> MetaData -> S.Set MetaValue
currentMetaDataValues f m = S.filter isSet (getAllMetaData f m)
currentMetaData :: MetaData -> MetaData
currentMetaData (MetaData m) = removeEmptyFields $ MetaData $
M.map (S.filter isSet) m
removeEmptyFields :: MetaData -> MetaData
removeEmptyFields (MetaData m) = MetaData $ M.filter (not . S.null) m
{- Gets currently set values, but also values that have been unset. -}
getAllMetaData :: MetaField -> MetaData -> S.Set MetaValue
getAllMetaData f (MetaData m) = fromMaybe S.empty (M.lookup f m)
{- Avoid putting too many fields in the map; extremely large maps make
- the seriaization test slow due to the sheer amount of data.
- It's unlikely that more than 100 fields of metadata will be used. -}
instance Arbitrary MetaData where
arbitrary = do
size <- arbitrarySizedBoundedIntegral `suchThat` (< 500)
MetaData . M.fromList <$> vector size
instance Arbitrary MetaValue where
arbitrary = MetaValue <$> arbitrary <*> arbitrary
instance Arbitrary MetaField where
arbitrary = MetaField <$> arbitrary `suchThat` legalField
prop_updateMetaData_sane :: MetaData -> MetaField -> MetaValue -> Bool
prop_updateMetaData_sane m f v = and
[ S.member v $ getAllMetaData f m'
, not (isSet v) || S.member v (currentMetaDataValues f m')
]
where
m' = updateMetaData f v m
prop_metadata_serialize :: MetaField -> MetaValue -> MetaData -> Bool
prop_metadata_serialize f v m = and
[ deserialize (serialize f) == Just f
, deserialize (serialize v) == Just v
, deserialize (serialize m') == Just m'
]
where
m' = removeEmptyFields m
|
