[07/10] diff --color-moved: shrink potential moved blocks as we go

Commit Message

Phillip Wood June 14, 2021, 1:04 p.m. UTC

From: Phillip Wood <[e-mail]>

Rather than setting `match` to NULL and then looping over the list of
potential matched blocks for a second time to remove blocks with no
matches just filter out the blocks with no matches as we go.

Signed-off-by: Phillip Wood <[e-mail]>
---
 diff.c | 42 ++++++------------------------------------
 1 file changed, 6 insertions(+), 36 deletions(-)

Patch

diff --git a/diff.c b/diff.c
index de6522a3a860..f60cce654c14 100644
--- a/diff.c
+++ b/diff.c
@@ -997,12 +997,12 @@  static void add_lines_to_move_detection(struct diff_options *o,
 static void pmb_advance_or_null(struct diff_options *o,
 				struct emitted_diff_symbol *l,
 				struct moved_block *pmb,
-				int pmb_nr)
+				int *pmb_nr)
 {
-	int i;
+	int i, j;
 	unsigned flags = o->color_moved_ws_handling & XDF_WHITESPACE_FLAGS;
 
-	for (i = 0; i < pmb_nr; i++) {
+	for (i = 0, j = 0; i < *pmb_nr; i++) {
 		int match;
 		struct moved_entry *prev = pmb[i].match;
 		struct moved_entry *cur = (prev && prev->next_line) ?
@@ -1017,37 +1017,9 @@  static void pmb_advance_or_null(struct diff_options *o,
 				xdiff_compare_lines(cur->es->line, cur->es->len,
 						    l->line, l->len, flags);
 		if (match)
-			pmb[i].match = cur;
-		else
-			moved_block_clear(&pmb[i]);
+			pmb[j++].match = cur;
 	}
-}
-
-static int shrink_potential_moved_blocks(struct moved_block *pmb,
-					 int pmb_nr)
-{
-	int lp, rp;
-
-	/* Shrink the set of potential block to the remaining running */
-	for (lp = 0, rp = pmb_nr - 1; lp <= rp;) {
-		while (lp < pmb_nr && pmb[lp].match)
-			lp++;
-		/* lp points at the first NULL now */
-
-		while (rp > -1 && !pmb[rp].match)
-			rp--;
-		/* rp points at the last non-NULL */
-
-		if (lp < pmb_nr && rp > -1 && lp < rp) {
-			pmb[lp] = pmb[rp];
-			memset(&pmb[rp], 0, sizeof(pmb[rp]));
-			rp--;
-			lp++;
-		}
-	}
-
-	/* Remember the number of running sets */
-	return rp + 1;
+	*pmb_nr = j;
 }
 
 /*
@@ -1140,9 +1112,7 @@  static void mark_color_as_moved(struct diff_options *o,
 			continue;
 		}
 
-		pmb_advance_or_null(o, l, pmb, pmb_nr);
-
-		pmb_nr = shrink_potential_moved_blocks(pmb, pmb_nr);
+		pmb_advance_or_null(o, l, pmb, &pmb_nr);
 
 		if (pmb_nr == 0) {
 			/*