diff.c: color moved lines differently, plain mode

Add the 'plain' mode for move detection of code. This omits the checking
for adjacent blocks, so it is not as useful. If you have a lot of the
same blocks moved in the same patch, the 'Zebra' would end up slow as it
is O(n^2) (n is number of same blocks). So this may be useful there and
is generally easy to add. Instead be very literal at the move detection,
do not skip over short blocks here.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/diff.c b/diff.c
index 084ecc5678..79ea592388 100644
--- a/diff.c
+++ b/diff.c
@@ -256,12 +256,14 @@ static int parse_color_moved(const char *arg)
 
 	if (!strcmp(arg, "no"))
 		return COLOR_MOVED_NO;
+	else if (!strcmp(arg, "plain"))
+		return COLOR_MOVED_PLAIN;
 	else if (!strcmp(arg, "zebra"))
 		return COLOR_MOVED_ZEBRA;
 	else if (!strcmp(arg, "default"))
 		return COLOR_MOVED_DEFAULT;
 	else
-		return error(_("color moved setting must be one of 'no', 'default', 'zebra'"));
+		return error(_("color moved setting must be one of 'no', 'default', 'zebra', 'plain'"));
 }
 
 int git_diff_ui_config(const char *var, const char *value, void *cb)
@@ -879,7 +881,8 @@ static void mark_color_as_moved(struct diff_options *o,
 		}
 
 		if (!match) {
-			if (block_length < COLOR_MOVED_MIN_BLOCK_LENGTH) {
+			if (block_length < COLOR_MOVED_MIN_BLOCK_LENGTH &&
+			    o->color_moved != COLOR_MOVED_PLAIN) {
 				for (i = 0; i < block_length + 1; i++) {
 					l = &o->emitted_symbols->buf[n - i];
 					l->flags &= ~DIFF_SYMBOL_MOVED_LINE;
@@ -893,6 +896,9 @@ static void mark_color_as_moved(struct diff_options *o,
 		l->flags |= DIFF_SYMBOL_MOVED_LINE;
 		block_length++;
 
+		if (o->color_moved == COLOR_MOVED_PLAIN)
+			continue;
+
 		/* Check any potential block runs, advance each or nullify */
 		for (i = 0; i < pmb_nr; i++) {
 			struct moved_entry *p = pmb[i];