1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
{- git-annex single-value log, pure operations
-
- Copyright 2014-2019 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Logs.SingleValue.Pure where
import Annex.Common
import Logs.Line
import Annex.VectorClock
import qualified Data.Set as S
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as L
import qualified Data.Attoparsec.ByteString.Lazy as A
import Data.Attoparsec.ByteString.Char8 (char)
import Data.ByteString.Builder
class SingleValueSerializable v where
serialize :: v -> B.ByteString
deserialize :: B.ByteString -> Maybe v
data LogEntry v = LogEntry
{ changed :: VectorClock
, value :: v
} deriving (Eq, Ord)
type Log v = S.Set (LogEntry v)
buildLog :: (SingleValueSerializable v) => Log v -> Builder
buildLog = mconcat . map genline . S.toList
where
genline (LogEntry c v) =
buildVectorClock c <> sp <> byteString (serialize v) <> nl
sp = charUtf8 ' '
nl = charUtf8 '\n'
parseLog :: (Ord v, SingleValueSerializable v) => L.ByteString -> Log v
parseLog = S.fromList . fromMaybe []
. A.maybeResult . A.parse (logParser <* A.endOfInput)
logParser :: SingleValueSerializable v => A.Parser [LogEntry v]
logParser = parseLogLines $ LogEntry
<$> vectorClockParser
<* char ' '
<*> (parsevalue =<< A.takeByteString)
where
parsevalue = maybe (fail "log line parse failure") return . deserialize
newestValue :: Log v -> Maybe v
newestValue s
| S.null s = Nothing
| otherwise = Just (value $ S.findMax s)
|
