[PATCH 1/3] tag: use skip_prefix instead of magic numbers

[Jacob Keller <jacob.e.keller@intel.com>]

From: Jeff King <peff@peff.net>

Make the parsing of the --sort parameter more readable by having
skip_prefix keep our pointer up to date.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
---
Fixed authorship. I don't expect this version to be taken, but it helps me in
review, and I figured it is good to send the whole series.

 builtin/tag.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/builtin/tag.c b/builtin/tag.c
index ef765563388c..7ccb6f3c581b 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -524,18 +524,12 @@ static int parse_opt_sort(const struct option *opt, const char *arg, int unset)
 	int *sort = opt->value;
 	int flags = 0;
 
-	if (*arg == '-') {
+	if (skip_prefix(arg, "-", &arg))
 		flags |= REVERSE_SORT;
-		arg++;
-	}
-	if (starts_with(arg, "version:")) {
+
+	if (skip_prefix(arg, "version:", &arg) || skip_prefix(arg, "v:", &arg))
 		*sort = VERCMP_SORT;
-		arg += 8;
-	} else if (starts_with(arg, "v:")) {
-		*sort = VERCMP_SORT;
-		arg += 2;
-	} else
-		*sort = STRCMP_SORT;
+
 	if (strcmp(arg, "refname"))
 		die(_("unsupported sort specification %s"), arg);
 	*sort |= flags;
-- 
2.0.1.475.g9b8d714