[WIP PATCH 01/22] parse-options: enhance STOP_AT_NON_OPTION

[Bo Yang <struggleyb.nku@gmail.com>]

Make parse_options_step() report PARSE_OPT_NON_OPTION instead
of PARSE_OPT_DONE to the caller, when it sees a non-option argument.

This will help implementing a nonstandard option syntax that
takes more than one parameters to an option, e.g.

  -L n1,m1 pathspec1 -L n2,m2 pathspec2

by directly calling parse_options_step(). The parse_options() API
only calls parse_options_step() once, and its callers are not affected
by this change.

Thanks-to: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Bo Yang <struggleyb.nku@gmail.com>
---
 parse-options.c |    3 ++-
 parse-options.h |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index 0fa79bc..cbb49d3 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -374,7 +374,7 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
 			if (parse_nodash_opt(ctx, arg, options) == 0)
 				continue;
 			if (ctx->flags & PARSE_OPT_STOP_AT_NON_OPTION)
-				break;
+				return PARSE_OPT_NON_OPTION;
 			ctx->out[ctx->cpidx++] = ctx->argv[0];
 			continue;
 		}
@@ -456,6 +456,7 @@ int parse_options(int argc, const char **argv, const char *prefix,
 	switch (parse_options_step(&ctx, options, usagestr)) {
 	case PARSE_OPT_HELP:
 		exit(129);
+	case PARSE_OPT_NON_OPTION:
 	case PARSE_OPT_DONE:
 		break;
 	default: /* PARSE_OPT_UNKNOWN */
diff --git a/parse-options.h b/parse-options.h
index 7435cdb..407697a 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -161,7 +161,8 @@ extern NORETURN void usage_msg_opt(const char *msg,
 enum {
 	PARSE_OPT_HELP = -1,
 	PARSE_OPT_DONE,
-	PARSE_OPT_UNKNOWN
+	PARSE_OPT_NON_OPTION,
+	PARSE_OPT_UNKNOWN,
 };
 
 /*
-- 
1.7.0.2.273.gc2413.dirty