Corrected some comments, thanks to Denis Vlasenko. Grep for 'safe'.
Please refer to this book for reasoning:
Cormen - Leiserson - Rivest: Introduction to Algorithms
1990 MIT
page 289, RB-DELETE-FIXUP(t,x)
Laszlo
--- linux-2.4.19/lib/rbtree.c Sat Aug 3 02:39:46 2002
+++ linux/lib/rbtree.c Sun Nov 24 22:59:38 2002
@@ -159,17 +159,16 @@
if (!other->rb_right ||
other->rb_right->rb_color == RB_BLACK)
{
- register rb_node_t * o_left;
- if ((o_left = other->rb_left))
- o_left->rb_color = RB_BLACK;
+ /* safe: other->rb_left can't be 0 */
+ other->rb_left->rb_color = RB_BLACK;
other->rb_color = RB_RED;
__rb_rotate_right(other, root);
other = parent->rb_right;
}
other->rb_color = parent->rb_color;
parent->rb_color = RB_BLACK;
- if (other->rb_right)
- other->rb_right->rb_color = RB_BLACK;
+ /* safe: other->rb_right can't be 0 */
+ other->rb_right->rb_color = RB_BLACK;
__rb_rotate_left(parent, root);
node = root->rb_node;
break;
@@ -199,17 +198,16 @@
if (!other->rb_left ||
other->rb_left->rb_color == RB_BLACK)
{
- register rb_node_t * o_right;
- if ((o_right = other->rb_right))
- o_right->rb_color = RB_BLACK;
+ /* safe: other->rb_right can't be 0 */
+ other->rb_right->rb_color = RB_BLACK;
other->rb_color = RB_RED;
__rb_rotate_left(other, root);
other = parent->rb_left;
}
other->rb_color = parent->rb_color;
parent->rb_color = RB_BLACK;
- if (other->rb_left)
- other->rb_left->rb_color = RB_BLACK;
+ /* safe: other->rb_left can't be 0 */
+ other->rb_left->rb_color = RB_BLACK;
__rb_rotate_right(parent, root);
node = root->rb_node;
break;
-
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This archive was generated by hypermail 2b29 : Sat Nov 30 2002 - 22:00:17 EST