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+{- git-annex command checks
+ -
+ - Common sanity checks for commands, and an interface to selectively
+ - remove them, or add others.
+ - 
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Checks where
+
+import Common.Annex
+import Types.Command
+import Init
+import qualified Annex
+
+commonChecks :: [CommandCheck]
+commonChecks = [fromOpt, toOpt, repoExists]
+
+repoExists :: CommandCheck
+repoExists = CommandCheck 0 ensureInitialized
+
+fromOpt :: CommandCheck
+fromOpt = CommandCheck 1 $ do
+	v <- Annex.getState Annex.fromremote
+	unless (v == Nothing) $ error "cannot use --from with this command"
+
+toOpt :: CommandCheck
+toOpt = CommandCheck 2 $ do
+	v <- Annex.getState Annex.toremote
+	unless (v == Nothing) $ error "cannot use --to with this command"
+
+checkCommand :: Command -> Annex ()
+checkCommand Command { cmdcheck = c } = sequence_ $ map runCheck c
+
+dontCheck :: CommandCheck -> Command -> Command
+dontCheck check cmd = mutateCheck cmd $ \c -> filter (/= check) c
+
+addCheck :: Annex () -> Command -> Command
+addCheck check cmd = mutateCheck cmd $
+	\c -> CommandCheck (length c + 100) check : c
+
+mutateCheck :: Command -> ([CommandCheck] -> [CommandCheck]) -> Command
+mutateCheck cmd@(Command { cmdcheck = c }) a = cmd { cmdcheck = a c }