revert: pass around rev-list args in already-parsed form

Since 7e2bfd3 (revert: allow cherry-picking more than one commit,
2010-07-02), the pick/revert machinery has kept track of the set of
commits to be cherry-picked or reverted using commit_argc and
commit_argv variables, storing the corresponding command-line
parameters.

Future callers as other commands are built in (am, rebase, sequencer)
may find it easier to pass rev-list options to this machinery in
already-parsed form.  Teach cmd_cherry_pick and cmd_revert to parse
the rev-list arguments in advance and pass the commit set to
pick_revisions() as a rev_info structure.

Original patch by Jonathan, tweaks and test from Ram.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Improved-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/revert.c

@@ -60,13 +60,14 @@ struct replay_opts {
 	int allow_rerere_auto;
 
 	int mainline;
-	int commit_argc;
-	const char **commit_argv;
 
 	/* Merge strategy */
 	const char *strategy;
 	const char **xopts;
 	size_t xopts_nr, xopts_alloc;
+
+	/* Only used by REPLAY_NONE */
+	struct rev_info *revs;
 };
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
@@ -169,9 +170,9 @@ static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 			die(_("program error"));
 	}
 
-	opts->commit_argc = parse_options(argc, argv, NULL, options, usage_str,
-					PARSE_OPT_KEEP_ARGV0 |
-					PARSE_OPT_KEEP_UNKNOWN);
+	argc = parse_options(argc, argv, NULL, options, usage_str,
+			PARSE_OPT_KEEP_ARGV0 |
+			PARSE_OPT_KEEP_UNKNOWN);
 
 	/* Check for incompatible subcommands */
 	verify_opt_mutually_compatible(me,
@@ -213,17 +214,27 @@ static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 				NULL);
 	}
 
-	else if (opts->commit_argc < 2)
-		usage_with_options(usage_str, options);
-
 	if (opts->allow_ff)
 		verify_opt_compatible(me, "--ff",
 				"--signoff", opts->signoff,
 				"--no-commit", opts->no_commit,
 				"-x", opts->record_origin,
 				"--edit", opts->edit,
 				NULL);
-	opts->commit_argv = argv;
+
+	if (opts->subcommand != REPLAY_NONE) {
+		opts->revs = NULL;
+	} else {
+		opts->revs = xmalloc(sizeof(*opts->revs));
+		init_revisions(opts->revs, NULL);
+		opts->revs->no_walk = 1;
+		if (argc < 2)
+			usage_with_options(usage_str, options);
+		argc = setup_revisions(argc, argv, opts->revs, NULL);
+	}
+
+	if (argc > 1)
+		usage_with_options(usage_str, options);
 }
 
 struct commit_message {
@@ -631,23 +642,15 @@ static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 	return res;
 }
 
-static void prepare_revs(struct rev_info *revs, struct replay_opts *opts)
+static void prepare_revs(struct replay_opts *opts)
 {
-	int argc;
-
-	init_revisions(revs, NULL);
-	revs->no_walk = 1;
 	if (opts->action != REVERT)
-		revs->reverse = 1;
+		opts->revs->reverse ^= 1;
 
-	argc = setup_revisions(opts->commit_argc, opts->commit_argv, revs, NULL);
-	if (argc > 1)
-		usage(*revert_or_cherry_pick_usage(opts));
-
-	if (prepare_revision_walk(revs))
+	if (prepare_revision_walk(opts->revs))
 		die(_("revision walk setup failed"));
 
-	if (!revs->commits)
+	if (!opts->revs->commits)
 		die(_("empty commit set passed"));
 }
 
@@ -844,14 +847,13 @@ static void read_populate_opts(struct replay_opts **opts_ptr)
 static void walk_revs_populate_todo(struct commit_list **todo_list,
 				struct replay_opts *opts)
 {
-	struct rev_info revs;
 	struct commit *commit;
 	struct commit_list **next;
 
-	prepare_revs(&revs, opts);
+	prepare_revs(opts);
 
 	next = todo_list;
-	while ((commit = get_revision(&revs)))
+	while ((commit = get_revision(opts->revs)))
 		next = commit_list_append(commit, next);
 }
 
@@ -1075,6 +1077,9 @@ static int pick_revisions(struct replay_opts *opts)
 	struct commit_list *todo_list = NULL;
 	unsigned char sha1[20];
 
+	if (opts->subcommand == REPLAY_NONE)
+		assert(opts->revs);
+
 	read_and_refresh_cache(opts);
 
 	/*

t/t3510-cherry-pick-sequence.sh

@@ -461,4 +461,9 @@ test_expect_success 'malformed instruction sheet 2' '
 	test_must_fail git cherry-pick --continue
 '
 
+test_expect_success 'empty commit set' '
+	pristine_detach initial &&
+	test_expect_code 128 git cherry-pick base..base
+'
+
 test_done