undo command

This commit was sponsored by Andrew Cant.

Git/DiffTree.hs

@@ -7,10 +7,12 @@
 
 module Git.DiffTree (
 	DiffTreeItem(..),
+	isDiffOf,
 	diffTree,
 	diffTreeRecursive,
 	diffIndex,
 	diffWorkTree,
+	diffLog,
 ) where
 
 import Numeric
@@ -33,6 +35,13 @@ data DiffTreeItem = DiffTreeItem
 	, file :: TopFilePath
 	} deriving Show
 
+{- Checks if the DiffTreeItem modifies a file with a given name
+ - or under a directory by that name. -}
+isDiffOf :: DiffTreeItem -> TopFilePath -> Bool
+isDiffOf diff f = case getTopFilePath f of
+	"" -> True -- top of repo contains all
+	d -> d `dirContains` getTopFilePath (file diff)
+
 {- Diffs two tree Refs. -}
 diffTree :: Ref -> Ref -> Repo -> IO ([DiffTreeItem], IO Bool)
 diffTree src dst = getdiff (Param "diff-tree")
@@ -66,16 +75,23 @@ diffIndex' ref params repo =
 		, return ([], return True)
 		)
 
+{- Runs git log in --raw mode to get the changes that were made in
+ - a particular commit. The output format is adjusted to be the same
+ - as diff-tree --raw._-}
+diffLog :: [CommandParam] -> Repo -> IO ([DiffTreeItem], IO Bool)
+diffLog params = getdiff (Param "log")
+	(Param "-n1" : Param "--abbrev=40" : Param "--pretty=format:" : params)
+
 getdiff :: CommandParam -> [CommandParam] -> Repo -> IO ([DiffTreeItem], IO Bool)
 getdiff command params repo = do
 	(diff, cleanup) <- pipeNullSplit ps repo
-	return (parseDiffTree diff, cleanup)
+	return (parseDiffRaw diff, cleanup)
   where
 	ps = command : Params "-z --raw --no-renames -l0" : params
 
-{- Parses diff-tree output. -}
-parseDiffTree :: [String] -> [DiffTreeItem]
-parseDiffTree l = go l []
+{- Parses --raw output used by diff-tree and git-log. -}
+parseDiffRaw :: [String] -> [DiffTreeItem]
+parseDiffRaw l = go l []
   where
 	go [] c = c
 	go (info:f:rest) c = go rest (mk info f : c)

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