refactoring and cleanup

No code changes.

Types/Command.hs

@@ -0,0 +1,45 @@
+{- git-annex command data types
+ -
+ - Copyright 2010-2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Types.Command where
+
+import Types
+
+{- A command runs in these stages.
+ -
+ - a. The check stage runs checks, that error out if
+ -    anything prevents the command from running. -}
+data CommandCheck = CommandCheck { idCheck :: Int, runCheck :: Annex () }
+{- b. The seek stage takes the parameters passed to the command,
+ -    looks through the repo to find the ones that are relevant
+ -    to that command (ie, new files to add), and generates
+ -    a list of start stage actions. -}
+type CommandSeek = [String] -> Annex [CommandStart]
+{- c. The start stage is run before anything is printed about the
+  -   command, is passed some input, and can early abort it
+  -   if the input does not make sense. It should run quickly and
+  -   should not modify Annex state. -}
+type CommandStart = Annex (Maybe CommandPerform)
+{- d. The perform stage is run after a message is printed about the command
+ -    being run, and it should be where the bulk of the work happens. -}
+type CommandPerform = Annex (Maybe CommandCleanup)
+{- e. The cleanup stage is run only if the perform stage succeeds, and it
+ -    returns the overall success/fail of the command. -}
+type CommandCleanup = Annex Bool
+
+{- A command is defined by specifying these things. -}
+data Command = Command {
+	cmdcheck :: [CommandCheck],
+	cmdname :: String,
+	cmdparams :: String,
+	cmdseek :: [CommandSeek],
+	cmddesc :: String
+}
+
+{- CommandCheck functions can be compared using their unique id. -}
+instance Eq CommandCheck where
+	a == b = idCheck a == idCheck b