[PATCH] parse-options: add PARSE_OPT_FAKELASTARG flag.

[Pierre Habouzit <madcoder@debian.org>]

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If you set this for a given flag, and the flag appears without a value on
the command line, then the `defval' is used to fake a new 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: Pierre Habouzit <madcoder@debian.org>
---

    >   (3) inspired from (1) and (2), have a flag for options that says
    >       "I do take an argument, but if I'm the last option on the
    >       command line, please fake this argument for me.
    >
    > I really like (3) more FWIW as it doesn't generate ambiguous
    > parsers like (2) would, and it's not horrible like (1). And cherry
    > on top it's pretty trivial to implement I think.

  And here it is, untested though (in the sense that I didn't test the
  new feature, but git is not broken with the patch).


 parse-options.c |   55 +++++++++++++++++++++++++++----------------------------
 parse-options.h |    1 +
 2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index a90b336..a63485c 100644
--- a/parse-options.c
+++ b/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 int opterror(const struct option *opt, const char *reason, int flags)
 {
 	if (flags & OPT_SHORT)
@@ -25,8 +14,24 @@ static int opterror(const struct option *opt, const char *reason, int flags)
 	return error("option `%s' %s", opt->long_name, reason);
 }
 
+static inline 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) {
+		p->argc--;
+		*arg = *++p->argv;
+	} else if (opt->flags & PARSE_OPT_FAKELASTARG) {
+		*arg = (const char *)opt->defval;
+	} 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;
@@ -52,7 +57,6 @@ 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)
@@ -74,17 +78,12 @@ 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:
@@ -94,9 +93,9 @@ 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) {
@@ -107,9 +106,9 @@ 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;
diff --git a/parse-options.h b/parse-options.h
index c5f0b4b..6e9edd1 100644
--- a/parse-options.h
+++ b/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_FAKELASTARG = 16,
 };
 
 struct option;
-- 
1.5.6.2.398.g3c3f1.dirty

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