[PATCH 8/9] range-diff: use a hunk callback

[Jeff King <peff@peff.net>]

When we count the lines in a diff, we don't actually care about the
contents of each line. By using a hunk callback, we tell xdiff that it
does not need to even bother generating a hunk header line, saving a
small amount of work.

Arguably we could even ignore the hunk headers completely, since we're
just computing a cost function between patches. But doing it this way
maintains the exact same behavior before and after.

Signed-off-by: Jeff King <peff@peff.net>
---
This one might be going overboard. It can be dropped without affecting
any of the other patches.

 range-diff.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/range-diff.c b/range-diff.c
index 245fc17fee..3958720f00 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -197,6 +197,12 @@ static void diffsize_consume(void *data, char *line, unsigned long len)
 	(*(int *)data)++;
 }
 
+static void diffsize_hunk(void *data, long ob, long on, long nb, long nn,
+			  const char *funcline, long funclen)
+{
+	diffsize_consume(data, NULL, 0);
+}
+
 static int diffsize(const char *a, const char *b)
 {
 	xpparam_t pp = { 0 };
@@ -210,7 +216,9 @@ static int diffsize(const char *a, const char *b)
 	mf2.size = strlen(b);
 
 	cfg.ctxlen = 3;
-	if (!xdi_diff_outf(&mf1, &mf2, NULL, diffsize_consume, &count, &pp, &cfg))
+	if (!xdi_diff_outf(&mf1, &mf2,
+			   diffsize_hunk, diffsize_consume, &count,
+			   &pp, &cfg))
 		return count;
 
 	error(_("failed to generate diff"));
-- 
2.19.1.1336.g081079ac04