add hasKey

Backend/File.hs

@@ -13,13 +13,16 @@ import LocationLog
 import Locations
 import qualified Remotes
 import qualified GitRepo as Git
+import Utility
+import Core
 
 backend = Backend {
 	name = "file",
 	getKey = keyValue,
 	storeFileKey = dummyStore,
 	retrieveKeyFile = copyKeyFile,
-	removeKey = dummyRemove
+	removeKey = dummyRemove,
+	hasKey = checkKeyFile
 }
 
 -- direct mapping from filename to key
@@ -29,8 +32,7 @@ keyValue file = return $ Just $ Key file
 {- This backend does not really do any independant data storage,
  - it relies on the file contents in .git/annex/ in this repo,
  - and other accessible repos. So storing a key is
- - a no-op. TODO until support is added for git annex --push otherrepo,
- - then these could implement that.. -}
+ - a no-op. -}
 dummyStore :: FilePath -> Key -> Annex (Bool)
 dummyStore file key = return True
 
@@ -38,6 +40,10 @@ dummyStore file key = return True
 dummyRemove :: Key -> Annex Bool
 dummyRemove url = return True
 
+{- Just check if the .git/annex/ file for the key exists. -}
+checkKeyFile :: Key -> Annex Bool
+checkKeyFile k = inAnnex backend k
+
 {- Try to find a copy of the file in one of the remotes,
  - and copy it over to this one. -}
 copyKeyFile :: Key -> FilePath -> Annex (Bool)

Backend/Url.hs

@@ -13,7 +13,8 @@ backend = Backend {
 	getKey = keyValue,
 	storeFileKey = dummyStore,
 	retrieveKeyFile = downloadUrl,
-	removeKey = dummyRemove
+	removeKey = dummyOk,
+	hasKey = dummyOk
 }
 
 -- cannot generate url from filename
@@ -24,9 +25,9 @@ keyValue file = return Nothing
 dummyStore :: FilePath -> Key -> Annex Bool
 dummyStore file url = return False
 
--- allow keys to be removed
-dummyRemove :: Key -> Annex Bool
-dummyRemove url = return True
+-- allow keys to be removed; presumably they can always be downloaded again
+dummyOk :: Key -> Annex Bool
+dummyOk url = return True
 
 downloadUrl :: Key -> FilePath -> Annex Bool
 downloadUrl url file = do

BackendTypes.hs

@@ -37,7 +37,9 @@ data Backend = Backend {
 	-- retrieves a key's contents to a file
 	retrieveKeyFile :: Key -> FilePath -> Annex Bool,
 	-- removes a key
-	removeKey :: Key -> Annex Bool
+	removeKey :: Key -> Annex Bool,
+	-- checks if a backend is storing the content of a key
+	hasKey :: Key -> Annex Bool
 }
 
 instance Show Backend where