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/*************************************************************************
* Copyright (C) 2009 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
#include "dimension_impl.h"
#include <stdlib.h>
static dmnsn_kD_splay_node *
dmnsn_new_kD_splay_node()
{
dmnsn_kD_splay_node *node = malloc(sizeof(dmnsn_kD_splay_node));
if (!node) {
dmnsn_error(DMNSN_SEVERITY_HIGH, "kD splay tree node allocation failed.");
}
return node;
}
static void
dmnsn_delete_kD_splay_node(dmnsn_kD_splay_node *node)
{
free(node);
}
/* Return an empty tree */
dmnsn_kD_splay_node *
dmnsn_new_kD_splay_tree()
{
return NULL;
}
/* Copy a kD splay tree */
dmnsn_kD_splay_node *dmnsn_kD_splay_copy(dmnsn_kD_splay_node *root)
{
dmnsn_kD_splay_node *node = NULL;
if (root) {
node = dmnsn_new_kD_splay_node();
*node = *root;
node->left = dmnsn_kD_splay_copy(node->left);
node->right = dmnsn_kD_splay_copy(node->right);
node->left->parent = node;
node->right->parent = node;
}
return node;
}
void
dmnsn_delete_kD_splay_tree(dmnsn_kD_splay_node *root)
{
if (root) {
dmnsn_delete_kD_splay_tree(root->left);
dmnsn_delete_kD_splay_tree(root->right);
dmnsn_delete_kD_splay_node(root);
}
}
/* Tree rotations */
static void dmnsn_kD_splay_rotate(dmnsn_kD_splay_node *node);
void
dmnsn_kD_splay(dmnsn_kD_splay_node *node)
{
while (node->parent) {
if (!node->parent->parent) {
/* Zig step - we are a child of the root node */
dmnsn_kD_splay_rotate(node);
return;
} else if ((node == node->parent->left
&& node->parent == node->parent->parent->left)
|| (node == node->parent->right
&& node->parent == node->parent->parent->right)) {
/* Zig-zig step - we are a child on the same side as our parent */
dmnsn_kD_splay_rotate(node->parent);
dmnsn_kD_splay_rotate(node);
} else {
/* Zig-zag step - we are a child on a different side than our parent is */
dmnsn_kD_splay_rotate(node);
dmnsn_kD_splay_rotate(node);
}
}
}
static void
dmnsn_kD_splay_rotate(dmnsn_kD_splay_node *node)
{
dmnsn_kD_splay_node *pivot;
if (node == node->parent->left) {
/* We are a left child */
pivot = node->right;
node->right = node->parent;
node->right->parent = node;
node->right->left = pivot;
pivot->parent = node->right;
node->parent = node->parent->parent;
} else {
/* We are a right child */
pivot = node->left;
node->left = node->parent;
node->left->parent = node;
node->left->right = pivot;
pivot->parent = node->left;
node->parent = node->parent->parent;
}
}
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