implement chunk logs

Slightly tricky as they are not normal UUIDBased logs, but are instead maps
from (uuid, chunksize) to chunkcount.

This commit was sponsored by Frank Thomas.

Logs/Chunk/Pure.hs

@@ -0,0 +1,32 @@
+{- Chunk logs, pure operations.
+ -
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Logs.Chunk.Pure where
+
+import Common.Annex
+import Logs.MapLog
+import Data.Int
+
+type ChunkSize = Int64
+
+type ChunkCount = Integer
+
+type ChunkLog = MapLog (UUID, ChunkSize) ChunkCount
+
+parseLog :: String -> ChunkLog
+parseLog = parseMapLog fieldparser valueparser
+  where
+	fieldparser s =
+		let (u,sz) = separate (== ':') s
+		in (,) <$> pure (toUUID u) <*> readish sz
+	valueparser = readish
+
+showLog :: ChunkLog -> String
+showLog = showMapLog fieldshower valueshower
+  where
+	fieldshower (u, sz) = fromUUID u ++ ':' : show sz
+	valueshower = show