parse-options: support --git-completion-helper

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 "NOCOMPLETE" flag.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/parse-options.c b/parse-options.c
index fca7159646c82cb9213e72afd94d8debc6bd4c51..29f4defdd6f2a85604d429d0278e0997378077b2 100644 (file)
--- a/parse-options.c
+++ b/parse-options.c
@@ -425,6 +425,46 @@ void parse_options_start(struct parse_opt_ctx_t *ctx,
        parse_options_check(options);
 }
 
+/*
+ * TODO: we are not completing the --no-XXX form yet because there are
+ * many options that do not suppress it properly.
+ */
+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_NOCOMPLETE))
+                       continue;
+
+               switch (opts->type) {
+               case OPTION_GROUP:
+                       continue;
+               case OPTION_STRING:
+               case OPTION_FILENAME:
+               case OPTION_INTEGER:
+               case OPTION_MAGNITUDE:
+               case OPTION_CALLBACK:
+                       if (opts->flags & PARSE_OPT_NOARG)
+                               break;
+                       if (opts->flags & PARSE_OPT_OPTARG)
+                               break;
+                       if (opts->flags & PARSE_OPT_LASTARG_DEFAULT)
+                               break;
+                       suffix = "=";
+                       break;
+               default:
+                       break;
+               }
+               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);
@@ -455,6 +495,10 @@ 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 (ctx->total == 1 && !strcmp(arg + 1, "-git-completion-helper"))
+                       return show_gitcomp(ctx, options);
+
                if (arg[1] != '-') {
                        ctx->opt = arg + 1;
                        switch (parse_short_opt(ctx, options)) {

diff --git a/parse-options.h b/parse-options.h
index af711227ae3aac7af07de0322a364ccac03b819d..a5caa0bb1db2be09833e7a753936280b6b323659 100644 (file)
--- a/parse-options.h
+++ b/parse-options.h
@@ -38,7 +38,8 @@ 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_NOCOMPLETE = 512
 };
 
 struct option;
@@ -89,6 +90,8 @@ typedef int parse_opt_ll_cb(struct parse_opt_ctx_t *ctx,
  *   PARSE_OPT_LITERAL_ARGHELP: says that argh shouldn't be enclosed in brackets
  *                             (i.e. '<argh>') in the help message.
  *                             Useful for options with multiple parameters.
+ *   PARSE_OPT_NOCOMPLETE: by default all visible options are completable
+ *                        by git-completion.bash. This option suppresses that.
  *
  * `callback`::
  *   pointer to the callback to use for OPTION_CALLBACK or