Re: [PATCH 5/8] builtin/config: track subcommands by action

> Part of `cmd_config()` is a rather unwieldy switch statement that
> invokes the correct subcommand function based on which action has been
> requested by the user. Now that we have converted actions to be tracked
> via a `OPT_CMDMODE()`, we know that the `actions` variable will
> only ever have at most one bit set. This allows us to convert the
> variable to use an `enum` instead, and thus to create an array that maps
> from this newly introduced `enum` to the corresponding subcommand
> function.
> 
> Refactor the code to do so. Besides allowing us to get rid of the giant
> switch statement, this refactoring will also make it easier to introduce
> proper subcommands to git-config(1).
> 
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  builtin/config.c | 207 +++++++++++++++++++++++------------------------
>  1 file changed, 99 insertions(+), 108 deletions(-)
> 
> diff --git a/builtin/config.c b/builtin/config.c
> index a6ab9b8204..0d58397ef5 100644
> --- a/builtin/config.c
> +++ b/builtin/config.c
> @@ -20,6 +20,26 @@ static const char *const builtin_config_usage[] = {
>  	NULL
>  };
>  
> +enum config_action {
> +	ACTION_NONE,
> +	ACTION_GET,
> +	ACTION_GET_ALL,
> +	ACTION_GET_REGEXP,
> +	ACTION_REPLACE_ALL,
> +	ACTION_ADD,
> +	ACTION_UNSET,
> +	ACTION_UNSET_ALL,
> +	ACTION_RENAME_SECTION,
> +	ACTION_REMOVE_SECTION,
> +	ACTION_LIST,
> +	ACTION_EDIT,
> +	ACTION_SET,
> +	ACTION_SET_ALL,
> +	ACTION_GET_COLOR,
> +	ACTION_GET_COLORBOOL,
> +	ACTION_GET_URLMATCH,
> +};
> +
>  static char *key;
>  static regex_t *key_regexp;
>  static const char *value_pattern;
> @@ -33,10 +53,12 @@ static char delim = '=';
>  static char key_delim = ' ';
>  static char term = '\n';
>  
> +static parse_opt_subcommand_fn *subcommand;
> +static enum config_action action = ACTION_NONE;
>  static int use_global_config, use_system_config, use_local_config;
>  static int use_worktree_config;
>  static struct git_config_source given_config_source;
> -static int actions, type;
> +static int type;
>  static char *default_value;
>  static int end_nul;
>  static int respect_includes_opt = -1;
> @@ -46,30 +68,6 @@ static int show_scope;
>  static int fixed_value;
>  static int config_flags;
>  
> -#define ACTION_GET (1<<0)
> -#define ACTION_GET_ALL (1<<1)
> -#define ACTION_GET_REGEXP (1<<2)
> -#define ACTION_REPLACE_ALL (1<<3)
> -#define ACTION_ADD (1<<4)
> -#define ACTION_UNSET (1<<5)
> -#define ACTION_UNSET_ALL (1<<6)
> -#define ACTION_RENAME_SECTION (1<<7)
> -#define ACTION_REMOVE_SECTION (1<<8)
> -#define ACTION_LIST (1<<9)
> -#define ACTION_EDIT (1<<10)
> -#define ACTION_SET (1<<11)
> -#define ACTION_SET_ALL (1<<12)
> -#define ACTION_GET_COLOR (1<<13)
> -#define ACTION_GET_COLORBOOL (1<<14)
> -#define ACTION_GET_URLMATCH (1<<15)
> -
> -/*
> - * The actions "ACTION_LIST | ACTION_GET_*" which may produce more than
> - * one line of output and which should therefore be paged.
> - */
> -#define PAGING_ACTIONS (ACTION_LIST | ACTION_GET_ALL | \
> -			ACTION_GET_REGEXP | ACTION_GET_URLMATCH)
> -
>  #define TYPE_BOOL		1
>  #define TYPE_INT		2
>  #define TYPE_BOOL_OR_INT	3
> @@ -842,6 +840,25 @@ static int cmd_config_get_colorbool(int argc, const char **argv, const char *pre
>  	return get_colorbool(argv[0], argc == 2);
>  }
>  
> +static parse_opt_subcommand_fn *subcommands_by_action[] = {
> +	[ACTION_LIST] = cmd_config_list,
> +	[ACTION_EDIT] = cmd_config_edit,
> +	[ACTION_SET] = cmd_config_set,
> +	[ACTION_SET_ALL] = cmd_config_set_all,
> +	[ACTION_ADD] = cmd_config_add,
> +	[ACTION_REPLACE_ALL] = cmd_config_replace_all,
> +	[ACTION_GET] = cmd_config_get,
> +	[ACTION_GET_ALL] = cmd_config_get_all,
> +	[ACTION_GET_REGEXP] = cmd_config_get_regexp,
> +	[ACTION_GET_URLMATCH] = cmd_config_get_urlmatch,
> +	[ACTION_UNSET] = cmd_config_unset,
> +	[ACTION_UNSET_ALL] = cmd_config_unset_all,
> +	[ACTION_RENAME_SECTION] = cmd_config_rename_section,
> +	[ACTION_REMOVE_SECTION] = cmd_config_remove_section,
> +	[ACTION_GET_COLOR] = cmd_config_get_color,
> +	[ACTION_GET_COLORBOOL] = cmd_config_get_colorbool,
> +};
> +
>  static struct option builtin_config_options[] = {
>  	OPT_GROUP(N_("Config file location")),
>  	OPT_BOOL(0, "global", &use_global_config, N_("use global config file")),
> @@ -851,20 +868,20 @@ static struct option builtin_config_options[] = {
>  	OPT_STRING('f', "file", &given_config_source.file, N_("file"), N_("use given config file")),
>  	OPT_STRING(0, "blob", &given_config_source.blob, N_("blob-id"), N_("read config from given blob object")),
>  	OPT_GROUP(N_("Action")),
> -	OPT_CMDMODE(0, "get", &actions, N_("get value: name [value-pattern]"), ACTION_GET),
> -	OPT_CMDMODE(0, "get-all", &actions, N_("get all values: key [value-pattern]"), ACTION_GET_ALL),
> -	OPT_CMDMODE(0, "get-regexp", &actions, N_("get values for regexp: name-regex [value-pattern]"), ACTION_GET_REGEXP),
> -	OPT_CMDMODE(0, "get-urlmatch", &actions, N_("get value specific for the URL: section[.var] URL"), ACTION_GET_URLMATCH),
> -	OPT_CMDMODE(0, "replace-all", &actions, N_("replace all matching variables: name value [value-pattern]"), ACTION_REPLACE_ALL),
> -	OPT_CMDMODE(0, "add", &actions, N_("add a new variable: name value"), ACTION_ADD),
> -	OPT_CMDMODE(0, "unset", &actions, N_("remove a variable: name [value-pattern]"), ACTION_UNSET),
> -	OPT_CMDMODE(0, "unset-all", &actions, N_("remove all matches: name [value-pattern]"), ACTION_UNSET_ALL),
> -	OPT_CMDMODE(0, "rename-section", &actions, N_("rename section: old-name new-name"), ACTION_RENAME_SECTION),
> -	OPT_CMDMODE(0, "remove-section", &actions, N_("remove a section: name"), ACTION_REMOVE_SECTION),
> -	OPT_CMDMODE('l', "list", &actions, N_("list all"), ACTION_LIST),
> -	OPT_CMDMODE('e', "edit", &actions, N_("open an editor"), ACTION_EDIT),
> -	OPT_CMDMODE(0, "get-color", &actions, N_("find the color configured: slot [default]"), ACTION_GET_COLOR),
> -	OPT_CMDMODE(0, "get-colorbool", &actions, N_("find the color setting: slot [stdout-is-tty]"), ACTION_GET_COLORBOOL),
> +	OPT_CMDMODE(0, "get", &action, N_("get value: name [value-pattern]"), ACTION_GET),

> +	OPT_CMDMODE(0, "get-all", &action, N_("get all values: key [value-pattern]"), ACTION_GET_ALL),
> +	OPT_CMDMODE(0, "get-regexp", &action, N_("get values for regexp: name-regex [value-pattern]"), ACTION_GET_REGEXP),
> +	OPT_CMDMODE(0, "get-urlmatch", &action, N_("get value specific for the URL: section[.var] URL"), ACTION_GET_URLMATCH),
> +	OPT_CMDMODE(0, "replace-all", &action, N_("replace all matching variables: name value [value-pattern]"), ACTION_REPLACE_ALL),
> +	OPT_CMDMODE(0, "add", &action, N_("add a new variable: name value"), ACTION_ADD),
> +	OPT_CMDMODE(0, "unset", &action, N_("remove a variable: name [value-pattern]"), ACTION_UNSET),
> +	OPT_CMDMODE(0, "unset-all", &action, N_("remove all matches: name [value-pattern]"), ACTION_UNSET_ALL),
> +	OPT_CMDMODE(0, "rename-section", &action, N_("rename section: old-name new-name"), ACTION_RENAME_SECTION),
> +	OPT_CMDMODE(0, "remove-section", &action, N_("remove a section: name"), ACTION_REMOVE_SECTION),
> +	OPT_CMDMODE('l', "list", &action, N_("list all"), ACTION_LIST),
> +	OPT_CMDMODE('e', "edit", &action, N_("open an editor"), ACTION_EDIT),
> +	OPT_CMDMODE(0, "get-color", &action, N_("find the color configured: slot [default]"), ACTION_GET_COLOR),
> +	OPT_CMDMODE(0, "get-colorbool", &action, N_("find the color setting: slot [stdout-is-tty]"), ACTION_GET_COLORBOOL),
>  	OPT_GROUP(N_("Type")),
>  	OPT_CALLBACK('t', "type", &type, N_("type"), N_("value is given this type"), option_parse_type),
>  	OPT_CALLBACK_VALUE(0, "bool", &type, N_("value is \"true\" or \"false\""), TYPE_BOOL),
> @@ -976,33 +993,43 @@ int cmd_config(int argc, const char **argv, const char *prefix)
>  		key_delim = '\n';
>  	}
>