parse-options: add PARSE_OPT_LASTARG_DEFAULT flag

If you set this for a given option, and the optoin appears without an
argument on the command line, then the `defval' is used as its argument.

Note that this flag is meaningless in presence of OPTARG or NOARG flags.
(in the current implementation it will be ignored, but don't rely on it).
Signed-off-by: NPierre Habouzit <madcoder@debian.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

parse-options.c

@@ -5,17 +5,6 @@
 #define OPT_SHORT 1
 #define OPT_UNSET 2
 
-static inline const char *get_arg(struct parse_opt_ctx_t *p)
-{
-	if (p->opt) {
-		const char *res = p->opt;
-		p->opt = NULL;
-		return res;
-	}
-	p->argc--;
-	return *++p->argv;
-}
-
 static inline const char *skip_prefix(const char *str, const char *prefix)
 {
 	size_t len = strlen(prefix);
@@ -31,8 +20,24 @@ static int opterror(const struct option *opt, const char *reason, int flags)
 	return error("option `%s' %s", opt->long_name, reason);
 }
 
+static int get_arg(struct parse_opt_ctx_t *p, const struct option *opt,
+		   int flags, const char **arg)
+{
+	if (p->opt) {
+		*arg = p->opt;
+		p->opt = NULL;
+	} else if (p->argc == 1 && (opt->flags & PARSE_OPT_LASTARG_DEFAULT)) {
+		*arg = (const char *)opt->defval;
+	} else if (p->argc) {
+		p->argc--;
+		*arg = *++p->argv;
+	} else
+		return opterror(opt, "requires a value", flags);
+	return 0;
+}
+
 static int get_value(struct parse_opt_ctx_t *p,
-                     const struct option *opt, int flags)
+		     const struct option *opt, int flags)
 {
 	const char *s, *arg;
 	const int unset = flags & OPT_UNSET;
@@ -58,7 +63,6 @@ static int get_value(struct parse_opt_ctx_t *p,
 		}
 	}
 
-	arg = p->opt ? p->opt : (p->argc > 1 ? p->argv[1] : NULL);
 	switch (opt->type) {
 	case OPTION_BIT:
 		if (unset)
@@ -80,17 +84,12 @@ static int get_value(struct parse_opt_ctx_t *p,
 		return 0;
 
 	case OPTION_STRING:
-		if (unset) {
+		if (unset)
 			*(const char **)opt->value = NULL;
-			return 0;
-		}
-		if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
+		else if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
 			*(const char **)opt->value = (const char *)opt->defval;
-			return 0;
-		}
-		if (!arg)
-			return opterror(opt, "requires a value", flags);
-		*(const char **)opt->value = get_arg(p);
+		else
+			return get_arg(p, opt, flags, (const char **)opt->value);
 		return 0;
 
 	case OPTION_CALLBACK:
@@ -100,9 +99,9 @@ static int get_value(struct parse_opt_ctx_t *p,
 			return (*opt->callback)(opt, NULL, 0) ? (-1) : 0;
 		if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
 			return (*opt->callback)(opt, NULL, 0) ? (-1) : 0;
-		if (!arg)
-			return opterror(opt, "requires a value", flags);
-		return (*opt->callback)(opt, get_arg(p), 0) ? (-1) : 0;
+		if (get_arg(p, opt, flags, &arg))
+			return -1;
+		return (*opt->callback)(opt, arg, 0) ? (-1) : 0;
 
 	case OPTION_INTEGER:
 		if (unset) {
@@ -113,9 +112,9 @@ static int get_value(struct parse_opt_ctx_t *p,
 			*(int *)opt->value = opt->defval;
 			return 0;
 		}
-		if (!arg)
-			return opterror(opt, "requires a value", flags);
-		*(int *)opt->value = strtol(get_arg(p), (char **)&s, 10);
+		if (get_arg(p, opt, flags, &arg))
+			return -1;
+		*(int *)opt->value = strtol(arg, (char **)&s, 10);
 		if (*s)
 			return opterror(opt, "expects a numerical value", flags);
 		return 0;

parse-options.h

@@ -28,6 +28,7 @@ enum parse_opt_option_flags {
 	PARSE_OPT_NOARG   = 2,
 	PARSE_OPT_NONEG   = 4,
 	PARSE_OPT_HIDDEN  = 8,
+	PARSE_OPT_LASTARG_DEFAULT = 16,
 };
 
 struct option;