Add support for subcommand names.

This should simplify using grecs in programs that implement a subcommand
notion (a la git or svn, e.g. myprod doit -n *).

* build-aux/getopt.m4 (STDFUNC): Initialize the subcmd member of
struct grecs_proginfo.
(OPTIONS_COMMAND_BEGIN): New macro.
* src/grecsopt.h (grecs_proginfo) <subcmd>: New member.
* src/opthelp.c (grecs_print_help): if defined, print the subcommand
and its aliases.

2 files changed, 27 insertions, 2 deletions

diff --git a/src/grecsopt.h b/src/grecsopt.h
index 2de9ea3..4c00e53 100644
--- a/src/grecsopt.h
+++ b/src/grecsopt.h
@@ -19,6 +19,7 @@
 
 struct grecs_proginfo {
         const char *progname;
+        char **subcmd;
         const char *docstring;
         const char *args_doc;
         struct grecs_opthelp *opthelp;
diff --git a/src/opthelp.c b/src/opthelp.c
index 58deeed..75e48d2 100644
--- a/src/opthelp.c
+++ b/src/opthelp.c
@@ -118,9 +118,20 @@ grecs_print_help(struct grecs_proginfo *pinfo)
         struct grecs_opthelp *opthelp;
         size_t optcount;
 
-        printf("%s %s [%s]... %s\n",
-               _("Usage:"), pinfo->progname, _("OPTION"),
+        printf("%s %s ",
+               _("Usage:"), pinfo->progname);
+        if (pinfo->subcmd)
+                printf("%s ", pinfo->subcmd[0]);
+        printf("[%s]... %s\n",
+               _("OPTION"),
                !ISEMPTY(pinfo->args_doc) ? gettext(pinfo->args_doc) : "");
+        if (pinfo->subcmd && pinfo->subcmd[1]) {
+                const char **p;
+
+                printf("%s: ", pinfo->subcmd[2] ? _("Aliases") : _("Alias"));
+                for (p = pinfo->subcmd + 1; *p; p++)
+                        printf("%s%c", *p, p[1] ? ' ' : '\n');
+        }
         if (!ISEMPTY(pinfo->docstring))
                 print_option_descr(gettext(pinfo->docstring), 0, RMARGIN);
         putchar('\n');
@@ -255,6 +266,8 @@ grecs_print_usage(struct grecs_proginfo *pinfo)
         buf = grecs_malloc(bufsize);
         
         n = snprintf(buf, bufsize, "%s %s ", _("Usage:"), pinfo->progname);
+        if (pinfo->subcmd)
+                n += snprintf(buf + n, bufsize - n, "%s ", pinfo->subcmd[0]);
         
         /* Print a list of short options without arguments. */
         for (i = nidx = 0; i < optcount; i++)
@@ -368,6 +381,17 @@ grecs_print_usage(struct grecs_proginfo *pinfo)
         }
 #endif
         FLUSH;
+
+        if (pinfo->subcmd && pinfo->subcmd[1]) {
+                const char **p;
+                
+                printf("%s: %s", pinfo->subcmd[2] ? _("Aliases") : _("Alias"),
+                        pinfo->progname);
+                for (p = pinfo->subcmd + 1; *p; p++)
+                        printf(" %s", *p);
+                putchar('\n');
+        }
+        
         free(optidx);
         free(buf);
 }