undo command

This commit was sponsored by Andrew Cant.

Git/UpdateIndex.hs

@@ -19,7 +19,8 @@ module Git.UpdateIndex (
 	updateIndexLine,
 	stageFile,
 	unstageFile,
-	stageSymlink
+	stageSymlink,
+	stageDiffTreeItem,
 ) where
 
 import Common
@@ -28,6 +29,7 @@ import Git.Types
 import Git.Command
 import Git.FilePath
 import Git.Sha
+import qualified Git.DiffTree as Diff
 
 {- Streamers are passed a callback and should feed it lines in the form
  - read by update-index, and generated by ls-tree. -}
@@ -95,7 +97,10 @@ stageFile sha filetype file repo = do
 unstageFile :: FilePath -> Repo -> IO Streamer
 unstageFile file repo = do
 	p <- toTopFilePath file repo
-	return $ pureStreamer $ "0 " ++ fromRef nullSha ++ "\t" ++ indexPath p
+	return $ unstageFile' p
+
+unstageFile' :: TopFilePath -> Streamer
+unstageFile' p = pureStreamer $ "0 " ++ fromRef nullSha ++ "\t" ++ indexPath p
 
 {- A streamer that adds a symlink to the index. -}
 stageSymlink :: FilePath -> Sha -> Repo -> IO Streamer
@@ -106,5 +111,11 @@ stageSymlink file sha repo = do
 		<*> toTopFilePath file repo
 	return $ pureStreamer line
 
+{- A streamer that applies a DiffTreeItem to the index. -}
+stageDiffTreeItem :: Diff.DiffTreeItem -> Streamer
+stageDiffTreeItem d = case toBlobType (Diff.dstmode d) of
+	Nothing -> unstageFile' (Diff.file d)
+	Just t -> pureStreamer $ updateIndexLine (Diff.dstsha d) t (Diff.file d)
+
 indexPath :: TopFilePath -> InternalGitPath
 indexPath = toInternalGitPath . getTopFilePath