Merge branch 'newchunks'

I am happy enough with this to make it live!

1 files changed, 15 insertions, 0 deletions

diff --git a/Types/Key.hs b/Types/Key.hs
index 90f66f23e..154e813ff 100644
--- a/Types/Key.hs
+++ b/Types/Key.hs
@@ -13,6 +13,8 @@ module Types.Key (
 	stubKey,
 	key2file,
 	file2key,
+	nonChunkKey,
+	chunkKeyOffset,
 
 	prop_idempotent_key_encode,
 	prop_idempotent_key_decode
@@ -47,6 +49,19 @@ stubKey = Key
 	, keyChunkNum = Nothing
 	}
 
+-- Gets the parent of a chunk key.
+nonChunkKey :: Key -> Key
+nonChunkKey k = k
+	{ keyChunkSize = Nothing
+	, keyChunkNum = Nothing
+	}
+
+-- Where a chunk key is offset within its parent.
+chunkKeyOffset :: Key -> Maybe Integer
+chunkKeyOffset k = (*)
+	<$> keyChunkSize k
+	<*> (pred <$> keyChunkNum k)
+
 fieldSep :: Char
 fieldSep = '-'