[RFC PATCH 1/7] rebase -i: Make option handling in pick_one more flexible

[Fabian Ruch <bafain@gmail.com>]

`pick_one` and `pick_one_preserving_merges` are wrappers around
`cherry-pick` in `rebase --interactive`. They take the hash of a commit
and build a `cherry-pick` command line that

 - respects the user-supplied merge options
 - disables complaints about empty commits
 - tries to fast-forward the rebase head unless rebase is forced
 - suppresses output unless the user requested higher verbosity
 - rewrites merge commits to point to their rebased parents.

`pick_one` is used to implement not only `pick` but also `squash`, which
amends the previous commit rather than creating a new one. When
`pick_one` is called from `squash`, it receives a second argument `-n`.
This tells `pick_one` to apply the changes to the index without
committing them. Since the argument is almost directly passed to
`cherry-pick`, we might want to do the same with other `cherry-pick`
options. Currently, `pick_one` expects `-n` to be the first and only
argument except for the commit hash.

Prepare `pick_one` for additional `cherry-pick` options by allowing `-n`
to appear anywhere before the commit hash in the argument list. Loop
over the argument list and pop each handled item until the commit hash
is the only parameter left on the list. If an option is not supported,
ignore it and issue a warning on the console. Construct a new arguments
list `extra_args` of recognized options that shall be passed to
`cherry-pick` on the command line.

Signed-off-by: Fabian Ruch <bafain@gmail.com>
---
 git-rebase--interactive.sh | 61 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 45 insertions(+), 16 deletions(-)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index f267d8b..ea5514e 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -237,8 +237,26 @@ git_sequence_editor () {
 
 pick_one () {
 	ff=--ff
+	extra_args=
+	while test $# -gt 0
+	do
+		case "$1" in
+		-n)
+			ff=
+			extra_args="$extra_args -n"
+			;;
+		-*)
+			warn "pick_one: ignored option -- $1"
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+	test $# -ne 1 && die "pick_one: wrong number of arguments"
+	sha1=$1
 
-	case "$1" in -n) sha1=$2; ff= ;; *) sha1=$1 ;; esac
 	case "$force_rebase" in '') ;; ?*) ff= ;; esac
 	output git rev-parse --verify $sha1 || die "Invalid commit name: $sha1"
 
@@ -248,24 +266,35 @@ pick_one () {
 	fi
 
 	test -d "$rewritten" &&
-		pick_one_preserving_merges "$@" && return
+		pick_one_preserving_merges $extra_args $sha1 && return
 	output eval git cherry-pick \
 			${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")} \
-			"$strategy_args" $empty_args $ff "$@"
+			"$strategy_args" $empty_args $ff $extra_args $sha1
 }
 
 pick_one_preserving_merges () {
 	fast_forward=t
-	case "$1" in
-	-n)
-		fast_forward=f
-		sha1=$2
-		;;
-	*)
-		sha1=$1
-		;;
-	esac
-	sha1=$(git rev-parse $sha1)
+	no_commit=
+	extra_args=
+	while test $# -gt 0
+	do
+		case "$1" in
+		-n)
+			fast_forward=f
+			extra_args="$extra_args -n"
+			no_commit=y
+			;;
+		-*)
+			warn "pick_one_preserving_merges: ignored option -- $1"
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+	test $# -ne 1 && die "pick_one_preserving_merges: wrong number of arguments"
+	sha1=$(git rev-parse $1)
 
 	if test -f "$state_dir"/current-commit
 	then
@@ -335,7 +364,7 @@ pick_one_preserving_merges () {
 	f)
 		first_parent=$(expr "$new_parents" : ' \([^ ]*\)')
 
-		if [ "$1" != "-n" ]
+		if test -z "$no_commit"
 		then
 			# detach HEAD to current parent
 			output git checkout $first_parent 2> /dev/null ||
@@ -344,7 +373,7 @@ pick_one_preserving_merges () {
 
 		case "$new_parents" in
 		' '*' '*)
-			test "a$1" = a-n && die "Refusing to squash a merge: $sha1"
+			test -n "$no_commit" && die "Refusing to squash a merge: $sha1"
 
 			# redo merge
 			author_script_content=$(get_author_ident_from_commit $sha1)
@@ -365,7 +394,7 @@ pick_one_preserving_merges () {
 		*)
 			output eval git cherry-pick \
 				${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")} \
-				"$strategy_args" "$@" ||
+				"$strategy_args" $extra_args $sha1 ||
 				die_with_patch $sha1 "Could not pick $sha1"
 			;;
 		esac
-- 
2.0.0