git: support --list-cmds=list-<category>

This allows us to select any group of commands by a category defined
in command-list.txt. This is an internal/hidden option so we don't
have to be picky about the category name or worried about exposing too
much.

This will be used later by git-completion.bash to retrieve certain
command groups.

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

1 files changed, 23 insertions, 0 deletions

diff --git a/help.c b/help.c
index d5ce9dfcbb..1117f7d1d1 100644
--- a/help.c
+++ b/help.c
@@ -329,6 +329,29 @@ void list_all_other_cmds(struct string_list *list)
 	clean_cmdnames(&other_cmds);
 }
 
+void list_cmds_by_category(struct string_list *list,
+			   const char *cat)
+{
+	int i, n = ARRAY_SIZE(command_list);
+	uint32_t cat_id = 0;
+
+	for (i = 0; category_names[i]; i++) {
+		if (!strcmp(cat, category_names[i])) {
+			cat_id = 1UL << i;
+			break;
+		}
+	}
+	if (!cat_id)
+		die(_("unsupported command listing type '%s'"), cat);
+
+	for (i = 0; i < n; i++) {
+		struct cmdname_help *cmd = command_list + i;
+
+		if (cmd->category & cat_id)
+			string_list_append(list, drop_prefix(cmd->name));
+	}
+}
+
 int is_in_cmdlist(struct cmdnames *c, const char *s)
 {
 	int i;