[PATCH 3/3] stash: support filename argument

[Thomas Gummerer <t.gummerer@gmail.com>]

While working on a repository, it's often helpful to stash the changes
of a single or multiple files, and leave others alone.  Unfortunately
git currently offers no such option.  git stash -p can be used to work
around this, but it's often impractical when there are a lot of changes
over multiple files.

Add an optional filename argument to git stash push, which allows for
stashing a single (or multiple) files.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 Documentation/git-stash.txt |  8 ++++++++
 git-stash.sh                | 42 ++++++++++++++++++++++++++++++++++--------
 t/t3903-stash.sh            | 27 +++++++++++++++++++++++++++
 3 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/Documentation/git-stash.txt b/Documentation/git-stash.txt
index 0ad5335a3e..871a3b246c 100644
--- a/Documentation/git-stash.txt
+++ b/Documentation/git-stash.txt
@@ -15,6 +15,9 @@ SYNOPSIS
 'git stash' branch <branchname> [<stash>]
 'git stash' [save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
 	     [-u|--include-untracked] [-a|--all] [<message>]]
+'git stash' push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
+	     [-u|--include-untracked] [-a|--all] [-m|--message <message>]]
+	     [--] [<paths>...]
 'git stash' clear
 'git stash' create [<message>]
 'git stash' store [-m|--message <message>] [-q|--quiet] <commit>
@@ -46,6 +49,7 @@ OPTIONS
 -------
 
 save [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
+push [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [-m|--message <message>] [--] [<paths>...]::
 
 	Save your local modifications to a new 'stash', and revert the
 	the changes in the working tree to match the index.
@@ -55,6 +59,10 @@ save [-p|--patch] [-k|--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q
 	only <message> does not trigger this action to prevent a misspelled
 	subcommand from making an unwanted stash.
 +
+If the paths argument is given in 'git stash push', only these files
+are put in the new 'stash'.  In addition only the indicated files are
+changed in the working tree to match the index.
++
 If the `--keep-index` option is used, all changes already added to the
 index are left intact.
 +
diff --git a/git-stash.sh b/git-stash.sh
index d6b4ae3290..7dcce629bd 100755
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -41,7 +41,7 @@ no_changes () {
 untracked_files () {
 	excl_opt=--exclude-standard
 	test "$untracked" = "all" && excl_opt=
-	git ls-files -o -z $excl_opt
+	git ls-files -o -z $excl_opt -- $1
 }
 
 clear_stash () {
@@ -56,6 +56,23 @@ clear_stash () {
 }
 
 create_stash () {
+	files=
+	while test $# != 0
+	do
+		case "$1" in
+		--)
+			shift
+			break
+			;;
+		--files)
+			;;
+		*)
+			files="$1 $files"
+			;;
+		esac
+		shift
+	done
+
 	stash_msg="$1"
 	untracked="$2"
 
@@ -92,7 +109,7 @@ create_stash () {
 		# Untracked files are stored by themselves in a parentless commit, for
 		# ease of unpacking later.
 		u_commit=$(
-			untracked_files | (
+			untracked_files $files | (
 				GIT_INDEX_FILE="$TMPindex" &&
 				export GIT_INDEX_FILE &&
 				rm -f "$TMPindex" &&
@@ -115,7 +132,7 @@ create_stash () {
 			git read-tree --index-output="$TMPindex" -m $i_tree &&
 			GIT_INDEX_FILE="$TMPindex" &&
 			export GIT_INDEX_FILE &&
-			git diff-index --name-only -z HEAD -- >"$TMP-stagenames" &&
+			git diff-index --name-only -z HEAD -- $files >"$TMP-stagenames" &&
 			git update-index -z --add --remove --stdin <"$TMP-stagenames" &&
 			git write-tree &&
 			rm -f "$TMPindex"
@@ -129,7 +146,7 @@ create_stash () {
 
 		# find out what the user wants
 		GIT_INDEX_FILE="$TMP-index" \
-			git add--interactive --patch=stash -- &&
+			git add--interactive --patch=stash -- $files &&
 
 		# state of the working tree
 		w_tree=$(GIT_INDEX_FILE="$TMP-index" git write-tree) ||
@@ -251,6 +268,8 @@ push_stash () {
 		shift
 	done
 
+	files="$*"
+
 	if test -n "$patch_mode" && test -n "$untracked"
 	then
 		die "$(gettext "Can't use --patch and --include-untracked or --all at the same time")"
@@ -265,18 +284,25 @@ push_stash () {
 	git reflog exists $ref_stash ||
 		clear_stash || die "$(gettext "Cannot initialize stash")"
 
-	create_stash "$stash_msg" $untracked
+	create_stash --files $files -- "$stash_msg" "$untracked"
 	store_stash -m "$stash_msg" -q $w_commit ||
 	die "$(gettext "Cannot save the current status")"
 	say "$(eval_gettext "Saved working directory and index state \$stash_msg")"
 
 	if test -z "$patch_mode"
 	then
-		git reset --hard ${GIT_QUIET:+-q}
+		if test -n "$files"
+		then
+			git reset -- $files
+			git checkout HEAD -- $(git ls-files --modified -- $files)
+			git clean --force --quiet -- $(git ls-files --others -- $files)
+		else
+			git reset --hard ${GIT_QUIET:+-q}
+		fi
 		test "$untracked" = "all" && CLEAN_X_OPTION=-x || CLEAN_X_OPTION=
 		if test -n "$untracked"
 		then
-			git clean --force --quiet -d $CLEAN_X_OPTION
+			git clean --force --quiet -d $CLEAN_X_OPTION -- $files
 		fi
 
 		if test "$keep_index" = "t" && test -n "$i_tree"
@@ -702,7 +728,7 @@ clear)
 	;;
 create)
 	shift
-	create_stash "$*" && echo "$w_commit"
+	create_stash -- "$*" && echo "$w_commit"
 	;;
 store)
 	shift
diff --git a/t/t3903-stash.sh b/t/t3903-stash.sh
index 0171b824c9..3e763ff766 100755
--- a/t/t3903-stash.sh
+++ b/t/t3903-stash.sh
@@ -784,4 +784,31 @@ test_expect_success 'push -m shows right message' '
 	test_cmp expect actual
 '
 
+test_expect_success 'stash -- <filename> stashes and restores the file' '
+	>foo &&
+	>bar &&
+	git add foo bar &&
+	git stash push -- foo &&
+	test_path_is_file bar &&
+	test_path_is_missing foo &&
+	git stash pop &&
+	test_path_is_file foo &&
+	test_path_is_file bar
+'
+
+test_expect_success 'stash with multiple filename arguments' '
+	>foo &&
+	>bar &&
+	>extra &&
+	git add foo bar extra &&
+	git stash push -- foo bar &&
+	test_path_is_missing bar &&
+	test_path_is_missing foo &&
+	test_path_is_file extra &&
+	git stash pop &&
+	test_path_is_file foo &&
+	test_path_is_file bar &&
+	test_path_is_file extra
+'
+
 test_done
-- 
2.11.0.483.g087da7b7c