Re: [PATCH v2 11/14] bisect: move even the option parsing to `bisect--helper`

> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> On our journey to a fully built-in `git bisect`, this is the
> second-to-last step.
>
> Side note: The `if (!strcmp(...)) ... else if (!strcmp(...)) ... else if
> (!strcmp(...)) ...` chain seen in this patch was not actually the first
> idea how to convert the command modes to sub-commands. Since the
> `bisect--helper` command already used the `parse-opions` API with neatly
> set-up command modes, naturally the idea was to use `PARSE_OPT_NODASH`
> to support proper sub-commands instead. However, the `parse-options` API
> is not set up for that, and even after making that option work with long
> options, it turned out that `STOP_AT_NON_OPTION` and `KEEP_UNKNOWN`
> would have to be used but these options were not designed to work
> together. So it would appear as if a lot of work would have to be done
> just to be able to use `parse_options()` just to parse the sub-command,
> instead of a simple `if...else if` chain, the latter being a
> dramatically simpler implementation.

> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  builtin/bisect--helper.c | 133 ++++++++++++++++-----------------------
>  git-bisect.sh            |  49 +--------------
>  2 files changed, 56 insertions(+), 126 deletions(-)
>
> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> index 5228964937d..ef0b06d594b 100644
> --- a/builtin/bisect--helper.c
> +++ b/builtin/bisect--helper.c
> @@ -20,18 +20,34 @@ static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
>  static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
>  static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
>  
> -static const char * const git_bisect_helper_usage[] = {
> -	N_("git bisect--helper --bisect-reset [<commit>]"),
> -	N_("git bisect--helper --bisect-terms [--term-good | --term-old | --term-bad | --term-new]"),
> -	N_("git bisect--helper --bisect-start [--term-{new,bad}=<term> --term-{old,good}=<term>]"
> -					    " [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<paths>...]"),
> -	N_("git bisect--helper --bisect-next"),
> -	N_("git bisect--helper [--bisect-state] (bad|new) [<rev>]"),
> -	N_("git bisect--helper [--bisect-state] (good|old) [<rev>...]"),
> -	N_("git bisect--helper --bisect-replay <filename>"),
> -	N_("git bisect--helper --bisect-skip [(<rev>|<range>)...]"),
> -	N_("git bisect--helper --bisect-visualize"),
> -	N_("git bisect--helper --bisect-run <cmd>..."),
> +static const char * const git_bisect_usage[] = {
> +	N_("git bisect help\n"
> +	   "\tprint this long help message."),
> +	N_("git bisect start [--term-{new,bad}=<term> --term-{old,good}=<term>]\n"
> +	   "\t\t [--no-checkout] [--first-parent] [<bad> [<good>...]] [--] [<pathspec>...]\n"
> +	   "\treset bisect state and start bisection."),
> +	N_("git bisect (bad|new) [<rev>]\n"
> +	   "\tmark <rev> a known-bad revision/\n"
> +	   "\t\ta revision after change in a given property."),
> +	N_("git bisect (good|old) [<rev>...]\n"
> +	   "\tmark <rev>... known-good revisions/\n"
> +	   "\t\trevisions before change in a given property."),
> +	N_("git bisect terms [--term-good | --term-bad]\n"
> +	   "\tshow the terms used for old and new commits (default: bad, good)"),
> +	N_("git bisect skip [(<rev>|<range>)...]\n"
> +	   "\tmark <rev>... untestable revisions."),
> +	N_("git bisect next\n"
> +	   "\tfind next bisection to test and check it out."),
> +	N_("git bisect reset [<commit>]\n"
> +	   "\tfinish bisection search and go back to commit."),
> +	N_("git bisect (visualize|view)\n"
> +	   "\tshow bisect status in gitk."),
> +	N_("git bisect replay <logfile>\n"
> +	   "\treplay bisection log."),
> +	N_("git bisect log\n"
> +	   "\tshow bisect log."),
> +	N_("git bisect run <cmd>...\n"
> +	   "\tuse <cmd>... to automatically bisect."),
>  	NULL
>  };

> @@ -1168,108 +1184,69 @@ static int bisect_run(struct bisect_terms *terms, const char **argv, int argc)
>  
>  int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
>  {
> -	enum {
> -		BISECT_START = 1,
> -		BISECT_STATE,
> -		BISECT_TERMS,
> -		BISECT_SKIP,
> -		BISECT_NEXT,
> -		BISECT_RESET,
> -		BISECT_VISUALIZE,
> -		BISECT_REPLAY,
> -		BISECT_LOG,
> -		BISECT_RUN,
> -	} cmdmode = 0;
>  	int res = 0;
>  	struct option options[] = {
> -		OPT_CMDMODE(0, "bisect-start", &cmdmode,
> -			 N_("start the bisect session"), BISECT_START),
> -		OPT_CMDMODE(0, "bisect-state", &cmdmode,
> -			 N_("mark the state of ref (or refs)"), BISECT_STATE),
> -		OPT_CMDMODE(0, "bisect-terms", &cmdmode,
> -			 N_("print out the bisect terms"), BISECT_TERMS),
> -		OPT_CMDMODE(0, "bisect-skip", &cmdmode,
> -			 N_("skip some commits for checkout"), BISECT_SKIP),
> -		OPT_CMDMODE(0, "bisect-next", &cmdmode,
> -			 N_("find the next bisection commit"), BISECT_NEXT),
> -		OPT_CMDMODE(0, "bisect-reset", &cmdmode,
> -			 N_("reset the bisection state"), BISECT_RESET),
> -		OPT_CMDMODE(0, "bisect-visualize", &cmdmode,
> -			 N_("visualize the bisection"), BISECT_VISUALIZE),
> -		OPT_CMDMODE(0, "bisect-replay", &cmdmode,
> -			 N_("replay the bisection process from the given file"), BISECT_REPLAY),
> -		OPT_CMDMODE(0, "bisect-log", &cmdmode,
> -			 N_("list the bisection steps so far"), BISECT_LOG),
> -		OPT_CMDMODE(0, "bisect-run", &cmdmode,
> -			 N_("use <cmd>... to automatically bisect."), BISECT_RUN),
>  		OPT_END()
>  	};
>  	struct bisect_terms terms = { .term_good = NULL, .term_bad = NULL };
> +	const char *command = argc > 1 ? argv[1] : "help";
>  
> -	argc = parse_options(argc, argv, prefix, options,
> -			     git_bisect_helper_usage,
> -			     PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_UNKNOWN);

>  
> -	switch (cmdmode ? cmdmode : BISECT_STATE) {
> -	case BISECT_START:
> +	argc -= 2;
> +	argv += 2;
> +
> +	if (!strcmp("start", command)) {
>  		set_terms(&terms, "bad", "good");
>  		res = bisect_start(&terms, argv, argc);
> -		break;
> -	case BISECT_TERMS:
> +	} else if (!strcmp("terms", command)) {
>  		if (argc > 1)
> -			die(_("--bisect-terms requires 0 or 1 argument"));
> +			die(_("'terms' requires 0 or 1 argument"));
>  		res = bisect_terms(&terms, argc == 1 ? argv[0] : NULL);
> -		break;
> -	case BISECT_SKIP:
> +	} else if (!strcmp("skip", command)) {
>  		set_terms(&terms, "bad", "good");
>  		get_terms(&terms);
>  		res = bisect_skip(&terms, argv, argc);
> -		break;
> -	case BISECT_NEXT:
> +	} else if (!strcmp("next", command)) {
>  		if (argc)
> -			die(_("--bisect-next requires 0 arguments"));
> +			die(_("'next' requires 0 arguments"));
>  		get_terms(&terms);
>  		res = bisect_next(&terms, prefix);
> -		break;
> -	case BISECT_RESET:
> +	} else if (!strcmp("reset", command)) {
>  		if (argc > 1)
> -			die(_("--bisect-reset requires either no argument or a commit"));
> +			die(_("'reset' requires either no argument or a commit"));
>  		res = bisect_reset(argc ? argv[0] : NULL);
> -		break;
> -	case BISECT_VISUALIZE:
> +	} else if (one_of(command, "visualize", "view", NULL)) {
>  		get_terms(&terms);
>  		res = bisect_visualize(&terms, argv, argc);
> -		break;
> -	case BISECT_REPLAY:
> +	} else if (!strcmp("replay", command)) {
>  		if (argc != 1)
>  			die(_("no logfile given"));
>  		set_terms(&terms, "bad", "good");
>  		res = bisect_replay(&terms, argv[0]);
> -		break;
> -	case BISECT_LOG:
> +	} else if (!strcmp("log", command)) {
>  		if (argc)
> -			die(_("--bisect-log requires 0 arguments"));
> +			die(_("'log' requires 0 arguments"));
>  		res = bisect_log();
> -		break;
> -	case BISECT_RUN:
> +	} else if (!strcmp("run", command)) {
>  		if (!argc)
>  			die(_("bisect run failed: no command provided."));
>  		get_terms(&terms);
>  		res = bisect_run(&terms, argv, argc);
> -		break;
> -	case BISECT_STATE:
> +	} else {
>  		set_terms(&terms, "bad", "good");
>  		get_terms(&terms);
> -		if (!cmdmode &&
> -		    (!argc || check_and_set_terms(&terms, argv[0]))) {
> -			char *msg = xstrfmt(_("unknown command: '%s'"), argv[0]);
> -			usage_msg_opt(msg, git_bisect_helper_usage, options);
> +		if (check_and_set_terms(&terms, command)) {
> +			char *msg = xstrfmt(_("unknown command: '%s'"), command);
> +			usage_msg_opt(msg, git_bisect_usage, options);

>  		}
> +		/* shift the `command` back in */
> +		argc++;
> +		argv--;
>  		res = bisect_state(&terms, argv, argc);
> -		break;
> -	default:
> -		BUG("unknown subcommand %d", cmdmode);
>  	}