range-diff: use a hunk callback

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/range-diff.c b/range-diff.c
index 0f4ce140dc539eb7d257f5da8b8e4250395c0c09..2ef372bbac6438624f45d04c2f5f41a7ddf99816 100644 (file)
--- a/range-diff.c
+++ b/range-diff.c
@@ -177,6 +177,12 @@ 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 };
@@ -190,7 +196,9 @@ 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"));