46 lines
1 KiB
Haskell
46 lines
1 KiB
Haskell
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{- git-annex single-value log, pure operations
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-
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- Copyright 2014 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Logs.SingleValue.Pure where
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import Annex.Common
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import Logs.Line
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import Annex.VectorClock
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import qualified Data.Set as S
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class SingleValueSerializable v where
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serialize :: v -> String
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deserialize :: String -> Maybe v
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data LogEntry v = LogEntry
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{ changed :: VectorClock
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, value :: v
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} deriving (Eq, Ord)
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type Log v = S.Set (LogEntry v)
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showLog :: (SingleValueSerializable v) => Log v -> String
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showLog = unlines . map showline . S.toList
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where
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showline (LogEntry c v) = unwords [formatVectorClock c, serialize v]
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parseLog :: (Ord v, SingleValueSerializable v) => String -> Log v
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parseLog = S.fromList . mapMaybe parse . splitLines
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where
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parse line = do
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let (sc, s) = splitword line
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c <- parseVectorClock sc
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v <- deserialize s
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Just (LogEntry c v)
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splitword = separate (== ' ')
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newestValue :: Log v -> Maybe v
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newestValue s
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| S.null s = Nothing
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| otherwise = Just (value $ S.findMax s)
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