split out three modules from Git

Constructors and configuration make sense in separate modules.
A separate Git.Types is needed to avoid cycles.

Git/Config.hs

@@ -0,0 +1,58 @@
+{- git repository configuration handling
+ -
+ - Copyright 2010,2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Git.Config (
+	get,
+	read,
+	hRead,
+	store
+) where
+
+import Prelude hiding (read)
+import System.Posix.Directory
+import Control.Exception (bracket_)
+import qualified Data.Map as M
+
+import Common
+import Git
+import Git.Types
+import qualified Git.Construct
+
+{- Returns a single git config setting, or a default value if not set. -}
+get :: String -> String -> Repo -> String
+get key defaultValue repo = M.findWithDefault defaultValue key (config repo)
+
+{- Runs git config and populates a repo with its config. -}
+read :: Repo -> IO Repo
+read repo@(Repo { location = Dir d }) = do
+	{- Cannot use pipeRead because it relies on the config having
+	   been already read. Instead, chdir to the repo. -}
+	cwd <- getCurrentDirectory
+	bracket_ (changeWorkingDirectory d) (changeWorkingDirectory cwd) $
+		pOpen ReadFromPipe "git" ["config", "--list"] $ hRead repo
+read r = assertLocal r $ error "internal"
+
+{- Reads git config from a handle and populates a repo with it. -}
+hRead :: Repo -> Handle -> IO Repo
+hRead repo h = do
+	val <- hGetContentsStrict h
+	store val repo
+
+{- Stores a git config into a repo, returning the new version of the repo.
+ - The git config may be multiple lines, or a single line. Config settings
+ - can be updated inrementally. -}
+store :: String -> Repo -> IO Repo
+store s repo = do
+	let repo' = repo { config = parse s `M.union` config repo }
+	rs <- Git.Construct.fromRemotes repo'
+	return $ repo' { remotes = rs }
+
+{- Parses git config --list output into a config map. -}
+parse :: String -> M.Map String String
+parse s = M.fromList $ map pair $ lines s
+	where
+		pair = separate (== '=')