diff: support anchoring line(s)

Teach diff a new algorithm, one that attempts to prevent user-specified
lines from appearing as a deletion or addition in the end result. The
end user can use this by specifying "--anchored=<text>" one or more
times when using Git commands like "diff" and "show".

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/diff.h b/diff.h
index 0fb18dd..7cf276f 100644
--- a/diff.h
+++ b/diff.h
@@ -166,6 +166,10 @@ struct diff_options {
 	const char *stat_sep;
 	long xdl_opts;
 
+	/* see Documentation/diff-options.txt */
+	char **anchors;
+	size_t anchors_nr, anchors_alloc;
+
 	int stat_width;
 	int stat_name_width;
 	int stat_graph_width;