Re: [PATCH 1/2] parse-options: support --git-completion-helper

[Jacob Keller <jacob.keller@gmail.com>]

On Tue, Jan 16, 2018 at 2:36 AM, Nguyễn Thái Ngọc Duy <pclouds@gmail.com> wrote:
> This option is designed to be used by git-completion.bash. For many
> simple cases, what we do in there is usually
>
>     __gitcomp "lots of completion options"
>
> which has to be manually updated when a new user-visible option is
> added. With support from parse-options, we can write
>
>     __gitcomp "$(git command --git-completion-helper)"
>
> and get that list directly from the parser for free. Dangerous/Unpopular
> options could be hidden with the new "NO_GITCOMP" flag.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>

Was this possibly avoided in the past due to being slower than simply
storing the list in the completion code itself?

I think this is a good idea myself.

Thanks,
Jake

> ---
>  parse-options.c | 37 +++++++++++++++++++++++++++++++++++++
>  parse-options.h |  6 ++++--
>  2 files changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/parse-options.c b/parse-options.c
> index fca7159646..6c542f44cf 100644
> --- a/parse-options.c
> +++ b/parse-options.c
> @@ -425,6 +425,35 @@ void parse_options_start(struct parse_opt_ctx_t *ctx,
>         parse_options_check(options);
>  }
>
> +static int show_gitcomp(struct parse_opt_ctx_t *ctx, const struct option *opts)
> +{
> +       for (; opts->type != OPTION_END; opts++) {
> +               const char *suffix;
> +
> +               if (!opts->long_name)
> +                       continue;
> +               if (opts->flags & (PARSE_OPT_HIDDEN | PARSE_OPT_NO_GITCOMP))
> +                       continue;
> +
> +               switch (opts->type) {
> +               case OPTION_GROUP:
> +                       continue;
> +               case OPTION_STRING:
> +               case OPTION_FILENAME:
> +               case OPTION_INTEGER:
> +               case OPTION_MAGNITUDE:
> +                       if (!(opts->flags & PARSE_OPT_OPTARG))
> +                               suffix = "=";
> +                       break;
> +               default:
> +                       suffix = "";
> +               }
> +               printf(" --%s%s", opts->long_name, suffix);
> +       }
> +       fputc('\n', stdout);
> +       exit(0);
> +}
> +
>  static int usage_with_options_internal(struct parse_opt_ctx_t *,
>                                        const char * const *,
>                                        const struct option *, int, int);
> @@ -434,6 +463,7 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
>                        const char * const usagestr[])
>  {
>         int internal_help = !(ctx->flags & PARSE_OPT_NO_INTERNAL_HELP);
> +       int internal_gitcomp = !(ctx->flags & PARSE_OPT_NO_INTERNAL_GITCOMP);
>         int err = 0;
>
>         /* we must reset ->opt, unknown short option leave it dangling */
> @@ -455,6 +485,11 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
>                 if (internal_help && ctx->total == 1 && !strcmp(arg + 1, "h"))
>                         goto show_usage;
>
> +               /* lone --git-completion-helper is asked by git-completion.bash */
> +               if (internal_gitcomp && ctx->total == 1 &&
> +                   !strcmp(arg + 1, "-git-completion-helper"))
> +                       goto show_git_comp;
> +
>                 if (arg[1] != '-') {
>                         ctx->opt = arg + 1;
>                         switch (parse_short_opt(ctx, options)) {
> @@ -521,6 +556,8 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
>         err = 1;
>   show_usage:
>         return usage_with_options_internal(ctx, usagestr, options, 0, err);
> + show_git_comp:
> +       return show_gitcomp(ctx, options);
>  }
>
>  int parse_options_end(struct parse_opt_ctx_t *ctx)
> diff --git a/parse-options.h b/parse-options.h
> index af711227ae..8a3389b05b 100644
> --- a/parse-options.h
> +++ b/parse-options.h
> @@ -27,7 +27,8 @@ enum parse_opt_flags {
>         PARSE_OPT_STOP_AT_NON_OPTION = 2,
>         PARSE_OPT_KEEP_ARGV0 = 4,
>         PARSE_OPT_KEEP_UNKNOWN = 8,
> -       PARSE_OPT_NO_INTERNAL_HELP = 16
> +       PARSE_OPT_NO_INTERNAL_HELP = 16,
> +       PARSE_OPT_NO_INTERNAL_GITCOMP = 32
>  };
>
>  enum parse_opt_option_flags {
> @@ -38,7 +39,8 @@ enum parse_opt_option_flags {
>         PARSE_OPT_LASTARG_DEFAULT = 16,
>         PARSE_OPT_NODASH = 32,
>         PARSE_OPT_LITERAL_ARGHELP = 64,
> -       PARSE_OPT_SHELL_EVAL = 256
> +       PARSE_OPT_SHELL_EVAL = 256,
> +       PARSE_OPT_NO_GITCOMP = 512
>  };
>
>  struct option;
> --
> 2.15.1.600.g899a5f85c6
>