[PATCH v2 05/17] git.c: convert --list-* to --list-cmds=*

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Even if these are hidden options, let's make them a bit more generic
since we're introducing more listing types shortly. The code is
structured to allow combining multiple listing types together because
we will soon add more types the 'builtins'.

'parseopt' remains separate because it has separate (SPC) to match
git-completion.bash needs and will not combine with others.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git.txt                  |  6 +++++
 contrib/completion/git-completion.bash |  2 +-
 git.c                                  | 37 +++++++++++++++++++++-----
 t/t0012-help.sh                        |  2 +-
 4 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/Documentation/git.txt b/Documentation/git.txt
index 4767860e72..2800e3d188 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -163,6 +163,12 @@ foo.bar= ...`) sets `foo.bar` to the empty string which `git config
 	Do not perform optional operations that require locks. This is
 	equivalent to setting the `GIT_OPTIONAL_LOCKS` to `0`.
 
+--list-cmds=group[,group...]::
+	List commands by group. This is an internal/experimental
+	option and may change or be removed in the future. Supported
+	groups are: builtins, parseopt (builtin commands that use
+	parse-options).
+
 GIT COMMANDS
 ------------
 
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index a757073945..3556838759 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -3049,7 +3049,7 @@ __git_complete_common () {
 __git_cmds_with_parseopt_helper=
 __git_support_parseopt_helper () {
 	test -n "$__git_cmds_with_parseopt_helper" ||
-		__git_cmds_with_parseopt_helper="$(__git --list-parseopt-builtins)"
+		__git_cmds_with_parseopt_helper="$(__git --list-cmds=parseopt)"
 
 	case " $__git_cmds_with_parseopt_helper " in
 	*" $1 "*)
diff --git a/git.c b/git.c
index 3a89893712..cd85355d81 100644
--- a/git.c
+++ b/git.c
@@ -38,6 +38,30 @@ static int use_pager = -1;
 
 static void list_builtins(unsigned int exclude_option, char sep);
 
+static int match_token(const char *spec, int len, const char *token)
+{
+	int token_len = strlen(token);
+
+	return len == token_len && !strncmp(spec, token, token_len);
+}
+
+static int list_cmds(const char *spec)
+{
+	while (*spec) {
+		const char *sep = strchrnul(spec, ',');
+		int len = sep - spec;
+
+		if (match_token(spec, len, "builtins"))
+			list_builtins(0, '\n');
+		else
+			die(_("unsupported command listing type '%s'"), spec);
+		spec += len;
+		if (*spec == ',')
+			spec++;
+	}
+	return 0;
+}
+
 static void commit_pager_choice(void) {
 	switch (use_pager) {
 	case 0:
@@ -223,12 +247,13 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 			}
 			(*argv)++;
 			(*argc)--;
-		} else if (!strcmp(cmd, "--list-builtins")) {
-			list_builtins(0, '\n');
-			exit(0);
-		} else if (!strcmp(cmd, "--list-parseopt-builtins")) {
-			list_builtins(NO_PARSEOPT, ' ');
-			exit(0);
+		} else if (skip_prefix(cmd, "--list-cmds=", &cmd)) {
+			if (!strcmp(cmd, "parseopt")) {
+				list_builtins(NO_PARSEOPT, ' ');
+				exit(0);
+			} else {
+				exit(list_cmds(cmd));
+			}
 		} else {
 			fprintf(stderr, _("unknown option: %s\n"), cmd);
 			usage(git_usage_string);
diff --git a/t/t0012-help.sh b/t/t0012-help.sh
index c096f33505..3c91a9024a 100755
--- a/t/t0012-help.sh
+++ b/t/t0012-help.sh
@@ -59,7 +59,7 @@ test_expect_success 'git help' '
 '
 
 test_expect_success 'generate builtin list' '
-	git --list-builtins >builtins
+	git --list-cmds=builtins >builtins
 '
 
 while read builtin
-- 
2.17.0.705.g3525833791