[PATCH 08/14] git: support --list-cmds=list-

[Nguyễn Thái Ngọc Duy]

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 <pclo...@gmail.com>
---
 generate-cmdlist.sh | 17 +++++++++++++++++
 git.c               |  7 +++++++
 help.c              | 23 +++++++++++++++++++++++
 help.h              |  2 ++
 4 files changed, 49 insertions(+)

diff --git a/generate-cmdlist.sh b/generate-cmdlist.sh
index 3bcc1ee57d..8d6d8b45ce 100755
--- a/generate-cmdlist.sh
+++ b/generate-cmdlist.sh
@@ -45,6 +45,21 @@ define_categories () {
        test "$bit" -gt 32 && die "Urgh.. too many categories?"
 }
 
+define_category_names () {
+       echo
+       echo "/* Category names */"
+       echo "static const char *category_names[] = {"
+       bit=0
+       category_list "$1" |
+       while read cat
+       do
+               echo "  \"$cat\", /* (1UL << $bit) */"
+               bit=$(($bit+1))
+       done
+       echo "  NULL"
+       echo "};"
+}
+
 print_command_list () {
        echo "static struct cmdname_help command_list[] = {"
 
@@ -70,4 +85,6 @@ struct cmdname_help {
 "
 define_categories "$1"
 echo
+define_category_names "$1"
+echo
 print_command_list "$1"
diff --git a/git.c b/git.c
index 10907f7266..4d5b8a9931 100644
--- a/git.c
+++ b/git.c
@@ -60,6 +60,13 @@ static int list_cmds(const char *spec)
                        list_all_main_cmds(&list);
                else if (match_token(spec, len, "others"))
                        list_all_other_cmds(&list);
+               else if (len > 5 && !strncmp(spec, "list-", 5)) {
+                       struct strbuf sb = STRBUF_INIT;
+
+                       strbuf_add(&sb, spec + 5, len - 5);
+                       list_cmds_by_category(&list, sb.buf);
+                       strbuf_release(&sb);
+               }
                else
                        die(_("unsupported command listing type '%s'"), spec);
                spec += len;
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;
diff --git a/help.h b/help.h
index 97e6c0965e..734bba32d3 100644
--- a/help.h
+++ b/help.h
@@ -21,6 +21,8 @@ static inline void mput_char(char c, unsigned int num)
 extern void list_common_cmds_help(void);
 extern void list_all_main_cmds(struct string_list *list);
 extern void list_all_other_cmds(struct string_list *list);
+extern void list_cmds_by_category(struct string_list *list,
+                                 const char *category);
 extern const char *help_unknown_cmd(const char *cmd);
 extern void load_command_list(const char *prefix,
                              struct cmdnames *main_cmds,
-- 
2.17.0.705.g3525833791