From ccc0e3990951712511ec237daedb01d7ab786f5f Mon Sep 17 00:00:00 2001
From: Alex Ionescu
Date: Tue, 8 Nov 2005 23:47:25 +0000
Subject: [PATCH] - Implement cases 2 & 4 of RtlSplayTree
svn path=/trunk/; revision=19076
---
reactos/lib/rtl/splaytree.c | 112 ++++++++++++++++++++++++++++++++++++
1 file changed, 112 insertions(+)
diff --git a/reactos/lib/rtl/splaytree.c b/reactos/lib/rtl/splaytree.c
index c315a72e7bb..6f3ea5b22a9 100644
--- a/reactos/lib/rtl/splaytree.c
+++ b/reactos/lib/rtl/splaytree.c
@@ -258,12 +258,124 @@ RtlSplay(PRTL_SPLAY_LINKS Links)
/* Case 2: P is the right child of G */
if (RtlIsRightChild(P))
{
+ /*
+ * P's left-child becomes G's right child and
+ * N's left-child becomes P's right child.
+ */
+ RtlRightChild(G) = RtlLeftChild(P);
+ RtlRightChild(P) = RtlLeftChild(N);
+ /*
+ * If they exist, update their parent pointers too,
+ * since they've changed trees.
+ */
+ if (RtlRightChild(G)) RtlParent(RtlRightChild(G)) = G;
+ if (RtlRightChild(P)) RtlParent(RtlRightChild(P)) = P;
+
+ /*
+ * Now we'll shove N all the way to the top.
+ * Check if G is the root first.
+ */
+ if (RtlIsRoot(G))
+ {
+ /* G doesn't have a parent, so N will become the root! */
+ RtlParent(N) = N;
+ }
+ else
+ {
+ /* G has a parent, so inherit it since we take G's place */
+ RtlParent(N) = RtlParent(G);
+
+ /*
+ * Now find out who was referencing G and have it reference
+ * N instead, since we're taking G's place.
+ */
+ if (RtlIsLeftChild(G))
+ {
+ /*
+ * G was a left child, so change its parent's left
+ * child link to point to N now.
+ */
+ RtlLeftChild(RtlParent(G)) = N;
+ }
+ else
+ {
+ /*
+ * G was a right child, so change its parent's right
+ * child link to point to N now.
+ */
+ RtlLeftChild(RtlParent(G)) = N;
+ }
+ }
+
+ /* Now N is on top, so P has become its child. */
+ RtlLeftChild(N) = P;
+ RtlParent(P) = N;
+
+ /* N is on top, P is its child, so G is grandchild. */
+ RtlLeftChild(P) = G;
+ RtlParent(G) = P;
}
/* Case 4: P is the left child of G */
else if (RtlIsLeftChild(P))
{
+ /*
+ * N's left-child becomes G's right child and
+ * N's right-child becomes P's left child.
+ */
+ RtlRightChild(P) = RtlLeftChild(N);
+ RtlLeftChild(G) = RtlRightChild(N);
+ /*
+ * If they exist, update their parent pointers too,
+ * since they've changed trees.
+ */
+ if (RtlRightChild(P)) RtlParent(RtlRightChild(P)) = P;
+ if (RtlLeftChild(G)) RtlParent(RtlLeftChild(G)) = G;
+
+ /*
+ * Now we'll shove N all the way to the top.
+ * Check if G is the root first.
+ */
+ if (RtlIsRoot(G))
+ {
+ /* G doesn't have a parent, so N will become the root! */
+ RtlParent(N) = N;
+ }
+ else
+ {
+ /* G has a parent, so inherit it since we take G's place */
+ RtlParent(N) = RtlParent(G);
+
+ /*
+ * Now find out who was referencing G and have it reference
+ * N instead, since we're taking G's place.
+ */
+ if (RtlIsLeftChild(G))
+ {
+ /*
+ * G was a left child, so change its parent's left
+ * child link to point to N now.
+ */
+ RtlLeftChild(RtlParent(G)) = N;
+ }
+ else
+ {
+ /*
+ * G was a right child, so change its parent's right
+ * child link to point to N now.
+ */
+ RtlLeftChild(RtlParent(G)) = N;
+ }
+ }
+
+ /* Now N is on top, so P has become its left child. */
+ RtlLeftChild(N) = P;
+ RtlParent(G) = N;
+
+ /* N is on top, P is its left child, so G is right child. */
+ RtlRightChild(N) = G;
+ RtlParent(P) = N;
}
/* "Finally" case: N doesn't have a grandparent => P is root */
else
--
2.17.1