diff: split off a function for --stat-* option parsing

As an optimization, the diff_opt_parse() switchboard has
a single case for all the --stat-* options.  Split it
off into a separate function so we can enhance it
without bringing code dangerously close to the right
margin.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff.c

@@ -3029,6 +3029,38 @@ int parse_long_opt(const char *opt, const char **argv,
 	return 2;
 }
 
+static int stat_opt(struct diff_options *options, const char **av)
+{
+	const char *arg = av[0];
+	char *end;
+	int width = options->stat_width;
+	int name_width = options->stat_name_width;
+
+	arg += strlen("--stat");
+	end = (char *)arg;
+
+	switch (*arg) {
+	case '-':
+		if (!prefixcmp(arg, "-width="))
+			width = strtoul(arg + 7, &end, 10);
+		else if (!prefixcmp(arg, "-name-width="))
+			name_width = strtoul(arg + 12, &end, 10);
+		break;
+	case '=':
+		width = strtoul(arg+1, &end, 10);
+		if (*end == ',')
+			name_width = strtoul(end+1, &end, 10);
+	}
+
+	/* Important! This checks all the error cases! */
+	if (*end)
+		return 0;
+	options->output_format |= DIFF_FORMAT_DIFFSTAT;
+	options->stat_name_width = name_width;
+	options->stat_width = width;
+	return 1;
+}
+
 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 {
 	const char *arg = av[0];
@@ -3070,33 +3102,9 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->output_format |= DIFF_FORMAT_NAME_STATUS;
 	else if (!strcmp(arg, "-s"))
 		options->output_format |= DIFF_FORMAT_NO_OUTPUT;
-	else if (!prefixcmp(arg, "--stat")) {
-		char *end;
-		int width = options->stat_width;
-		int name_width = options->stat_name_width;
-		arg += 6;
-		end = (char *)arg;
-
-		switch (*arg) {
-		case '-':
-			if (!prefixcmp(arg, "-width="))
-				width = strtoul(arg + 7, &end, 10);
-			else if (!prefixcmp(arg, "-name-width="))
-				name_width = strtoul(arg + 12, &end, 10);
-			break;
-		case '=':
-			width = strtoul(arg+1, &end, 10);
-			if (*end == ',')
-				name_width = strtoul(end+1, &end, 10);
-		}
-
-		/* Important! This checks all the error cases! */
-		if (*end)
-			return 0;
-		options->output_format |= DIFF_FORMAT_DIFFSTAT;
-		options->stat_name_width = name_width;
-		options->stat_width = width;
-	}
+	else if (!prefixcmp(arg, "--stat"))
+		/* --stat, --stat-width, or --stat-name-width */
+		return stat_opt(options, av);
 
 	/* renames options */
 	else if (!prefixcmp(arg, "-B")) {