summaryrefslogtreecommitdiff
path: root/xdiff-interface.c
diff options
context:
space:
mode:
authorJunio C Hamano <gitster@pobox.com>2007-12-13 22:24:18 (GMT)
committerJunio C Hamano <gitster@pobox.com>2007-12-14 07:04:26 (GMT)
commit913b45f51b151d8e29f86df67d3e10853d831470 (patch)
tree8c081b6a2a505d3c202a200c71aab055d4f24e4f /xdiff-interface.c
parentc279d7e9869740a6d64b0d1d70f7968af68d2071 (diff)
downloadgit-913b45f51b151d8e29f86df67d3e10853d831470.zip
git-913b45f51b151d8e29f86df67d3e10853d831470.tar.gz
git-913b45f51b151d8e29f86df67d3e10853d831470.tar.bz2
xdi_diff: trim common trailing lines
This implements earlier Linus's optimization to trim common lines at the end before passing them down to low level xdiff interface for all of our xdiff users. We could later enhance this to also trim common leading lines, but that would need tweaking the output function to add the number of lines trimmed at the beginning to line numbers that appear in the hunk headers. Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'xdiff-interface.c')
-rw-r--r--xdiff-interface.c34
1 files changed, 33 insertions, 1 deletions
diff --git a/xdiff-interface.c b/xdiff-interface.c
index 69a022c..f2cd488 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -103,9 +103,41 @@ int xdiff_outf(void *priv_, mmbuffer_t *mb, int nbuf)
return 0;
}
+/*
+ * Trim down common substring at the end of the buffers,
+ * but leave at least ctx lines at the end.
+ */
+static void trim_common_tail(mmfile_t *a, mmfile_t *b, int ctx)
+{
+ const int blk = 1024;
+ long trimmed = 0, recovered = 0;
+ int i;
+ char *ap = a->ptr + a->size;
+ char *bp = b->ptr + b->size;
+ long smaller = (a->size < b->size) ? a->size : b->size;
+
+ while (blk + trimmed <= smaller && !memcmp(ap - blk, bp - blk, blk)) {
+ trimmed += blk;
+ ap -= blk;
+ bp -= blk;
+ }
+
+ for (i = 0, recovered = 0; recovered < trimmed && i <= ctx; i++) {
+ while (recovered < trimmed && ap[recovered] != '\n')
+ recovered++;
+ }
+ a->size -= (trimmed - recovered);
+ b->size -= (trimmed - recovered);
+}
+
int xdi_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, xdemitconf_t const *xecfg, xdemitcb_t *xecb)
{
- return xdl_diff(mf1, mf2, xpp, xecfg, xecb);
+ mmfile_t a = *mf1;
+ mmfile_t b = *mf2;
+
+ trim_common_tail(&a, &b, xecfg->ctxlen);
+
+ return xdl_diff(&a, &b, xpp, xecfg, xecb);
}
int read_mmfile(mmfile_t *ptr, const char *filename)