[PATCH v6 07/13] completion: implement and use --list-cmds=main,others

[Nguyễn Thái Ngọc Duy]

Instead of parsing "git help -a" output, which is tricky to get right,
less elegant and also slow, make git provide the list in a
machine-friendly form. This adds two separate listing types, main and
others, instead of just "all" for more flexibility.
---
 contrib/completion/git-completion.bash |  2 +-
 git.c                                  |  4 ++++
 help.c                                 | 32 ++++++++++++++++++++++++++
 help.h                                 |  4 ++++
 4 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/contrib/completion/git-completion.bash 
b/contrib/completion/git-completion.bash
index 3556838759..62ca8641f4 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -839,7 +839,7 @@ __git_commands () {
        then
                printf "%s" "${GIT_TESTING_COMMAND_COMPLETION}"
        else
-               git help -a|egrep '^  [a-zA-Z0-9]'
+               git --list-cmds=main,others
        fi
 }
 
diff --git a/git.c b/git.c
index a0477c459e..3c032d01fc 100644
--- a/git.c
+++ b/git.c
@@ -49,6 +49,10 @@ static int list_cmds(const char *spec)
 
                if (len == 8 && !strncmp(spec, "builtins", 8))
                        list_builtins(&list, 0);
+               else if (len == 4 && !strncmp(spec, "main", 4))
+                       list_all_main_cmds(&list);
+               else if (len == 6 && !strncmp(spec, "others", 6))
+                       list_all_other_cmds(&list);
                else
                        die(_("unsupported command listing type '%s'"), spec);
                spec += len;
diff --git a/help.c b/help.c
index 2d6a3157f8..d5ce9dfcbb 100644
--- a/help.c
+++ b/help.c
@@ -297,6 +297,38 @@ void list_common_cmds_help(void)
        print_cmd_by_category(common_categories);
 }
 
+void list_all_main_cmds(struct string_list *list)
+{
+       struct cmdnames main_cmds, other_cmds;
+       int i;
+
+       memset(&main_cmds, 0, sizeof(main_cmds));
+       memset(&other_cmds, 0, sizeof(other_cmds));
+       load_command_list("git-", &main_cmds, &other_cmds);
+
+       for (i = 0; i < main_cmds.cnt; i++)
+               string_list_append(list, main_cmds.names[i]->name);
+
+       clean_cmdnames(&main_cmds);
+       clean_cmdnames(&other_cmds);
+}
+
+void list_all_other_cmds(struct string_list *list)
+{
+       struct cmdnames main_cmds, other_cmds;
+       int i;
+
+       memset(&main_cmds, 0, sizeof(main_cmds));
+       memset(&other_cmds, 0, sizeof(other_cmds));
+       load_command_list("git-", &main_cmds, &other_cmds);
+
+       for (i = 0; i < other_cmds.cnt; i++)
+               string_list_append(list, other_cmds.names[i]->name);
+
+       clean_cmdnames(&main_cmds);
+       clean_cmdnames(&other_cmds);
+}
+
 int is_in_cmdlist(struct cmdnames *c, const char *s)
 {
        int i;
diff --git a/help.h b/help.h
index b21d7c94e8..97e6c0965e 100644
--- a/help.h
+++ b/help.h
@@ -1,6 +1,8 @@
 #ifndef HELP_H
 #define HELP_H
 
+struct string_list;
+
 struct cmdnames {
        int alloc;
        int cnt;
@@ -17,6 +19,8 @@ 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 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