diff mbox series

[v3,11/15] diff --color-moved: shrink potential moved blocks as we go

Message ID 078c04d4a66c51acdb3477b49813a9dc1c144f15.1635336263.git.gitgitgadget@gmail.com (mailing list archive)
State New, archived
Headers show
Series diff --color-moved[-ws] speedups | expand

Commit Message

Phillip Wood Oct. 27, 2021, 12:04 p.m. UTC 
From: Phillip Wood <phillip.wood@dunelm.org.uk>

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 <phillip.wood@dunelm.org.uk>
---
 diff.c | 44 ++++++++------------------------------------
 1 file changed, 8 insertions(+), 36 deletions(-)
diff mbox series

Patch

diff --git a/diff.c b/diff.c
index 51f092e724e..626fd47aa0e 100644
--- a/diff.c
+++ b/diff.c
@@ -996,12 +996,12 @@  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) ?
@@ -1015,38 +1015,12 @@  static void pmb_advance_or_null(struct diff_options *o,
 			match = cur &&
 				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]);
-	}
-}
-
-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++;
+		if (match) {
+			pmb[j] = pmb[i];
+			pmb[j++].match = cur;
 		}
 	}
-
-	/* Remember the number of running sets */
-	return rp + 1;
+	*pmb_nr = j;
 }
 
 static void fill_potential_moved_blocks(struct diff_options *o,
@@ -1181,9 +1155,7 @@  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) {
 			int contiguous = adjust_last_block(o, n, block_length);