/*

  Red Black Trees

  (C) 1999  Andrea Arcangeli <andrea@suse.de>

  (C) 2002  David Woodhouse <dwmw2@infradead.org>

  This program is free software; you can redistribute it and/or modify

  it under the terms of the GNU General Public License as published by

  the Free Software Foundation; either version 2 of the License, or

  (at your option) any later version.

  This program 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 General Public License for more details.

  You should have received a copy of the GNU General Public License

  along with this program; if not, write to the Free Software

  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  linux/lib/rbtree.c

*/

#include "rbtree.h"

static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)

{

	struct rb_node *right = node->rb_right;

	struct rb_node *parent = rb_parent(node);

	if ((node->rb_right = right->rb_left))

		rb_set_parent(right->rb_left, node);

	right->rb_left = node;

	rb_set_parent(right, parent);

	if (parent)

	{

		if (node == parent->rb_left)

			parent->rb_left = right;

		else

			parent->rb_right = right;

	}

	else

		root->rb_node = right;

	rb_set_parent(node, right);

}

static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)

{

	struct rb_node *left = node->rb_left;

	struct rb_node *parent = rb_parent(node);

	if ((node->rb_left = left->rb_right))

		rb_set_parent(left->rb_right, node);

	left->rb_right = node;

	rb_set_parent(left, parent);

	if (parent)

	{

		if (node == parent->rb_right)

			parent->rb_right = left;

		else

			parent->rb_left = left;

	}

	else

		root->rb_node = left;

	rb_set_parent(node, left);

}

void rb_insert_color(struct rb_node *node, struct rb_root *root)

{

	struct rb_node *parent, *gparent;

	while ((parent = rb_parent(node)) && rb_is_red(parent))

	{

		gparent = rb_parent(parent);

		if (parent == gparent->rb_left)

		{

			{

				register struct rb_node *uncle = gparent->rb_right;

				if (uncle && rb_is_red(uncle))

				{

					rb_set_black(uncle);

					rb_set_black(parent);

					rb_set_red(gparent);

					node = gparent;

					continue;

				}

			}

			if (parent->rb_right == node)

			{

				register struct rb_node *tmp;

				__rb_rotate_left(parent, root);

				tmp = parent;

				parent = node;

				node = tmp;

			}

			rb_set_black(parent);

			rb_set_red(gparent);

			__rb_rotate_right(gparent, root);

		} else {

			{

				register struct rb_node *uncle = gparent->rb_left;

				if (uncle && rb_is_red(uncle))

				{

					rb_set_black(uncle);

					rb_set_black(parent);

					rb_set_red(gparent);

					node = gparent;

					continue;

				}

			}

			if (parent->rb_left == node)

			{

				register struct rb_node *tmp;

				__rb_rotate_right(parent, root);

				tmp = parent;

				parent = node;

				node = tmp;

			}

			rb_set_black(parent);

			rb_set_red(gparent);

			__rb_rotate_left(gparent, root);

		}

	}

	rb_set_black(root->rb_node);

}

static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,

			     struct rb_root *root)

{

	struct rb_node *other;

	while ((!node || rb_is_black(node)) && node != root->rb_node)

	{

		if (parent->rb_left == node)

		{

			other = parent->rb_right;

			if (rb_is_red(other))

			{

				rb_set_black(other);

				rb_set_red(parent);

				__rb_rotate_left(parent, root);

				other = parent->rb_right;

			}

			if ((!other->rb_left || rb_is_black(other->rb_left)) &&

			    (!other->rb_right || rb_is_black(other->rb_right)))

			{

				rb_set_red(other);

				node = parent;

				parent = rb_parent(node);

			}

			else

			{

				if (!other->rb_right || rb_is_black(other->rb_right))

				{

					struct rb_node *o_left;

					if ((o_left = other->rb_left))

						rb_set_black(o_left);

					rb_set_red(other);

					__rb_rotate_right(other, root);

					other = parent->rb_right;

				}

				rb_set_color(other, rb_color(parent));

				rb_set_black(parent);

				if (other->rb_right)

					rb_set_black(other->rb_right);

				__rb_rotate_left(parent, root);

				node = root->rb_node;

				break;

			}

		}

		else

		{

			other = parent->rb_left;

			if (rb_is_red(other))

			{

				rb_set_black(other);

				rb_set_red(parent);

				__rb_rotate_right(parent, root);

				other = parent->rb_left;

			}

			if ((!other->rb_left || rb_is_black(other->rb_left)) &&

			    (!other->rb_right || rb_is_black(other->rb_right)))

			{

				rb_set_red(other);

				node = parent;

				parent = rb_parent(node);

			}

			else

			{

				if (!other->rb_left || rb_is_black(other->rb_left))

				{

					register struct rb_node *o_right;

					if ((o_right = other->rb_right))

						rb_set_black(o_right);

					rb_set_red(other);

					__rb_rotate_left(other, root);

					other = parent->rb_left;

				}

				rb_set_color(other, rb_color(parent));

				rb_set_black(parent);

				if (other->rb_left)

					rb_set_black(other->rb_left);

				__rb_rotate_right(parent, root);

				node = root->rb_node;

				break;

			}

		}

	}

	if (node)

		rb_set_black(node);

}

void rb_erase(struct rb_node *node, struct rb_root *root)

{

	struct rb_node *child, *parent;

	int color;

	if (!node->rb_left)

		child = node->rb_right;

	else if (!node->rb_right)

		child = node->rb_left;

	else

	{

		struct rb_node *old = node, *left;

		node = node->rb_right;

		while ((left = node->rb_left) != NULL)

			node = left;

		child = node->rb_right;

		parent = rb_parent(node);

		color = rb_color(node);

		if (child)

			rb_set_parent(child, parent);

		if (parent == old) {

			parent->rb_right = child;

			parent = node;

		} else

			parent->rb_left = child;

		node->rb_parent_color = old->rb_parent_color;

		node->rb_right = old->rb_right;

		node->rb_left = old->rb_left;

		if (rb_parent(old))

		{

			if (rb_parent(old)->rb_left == old)

				rb_parent(old)->rb_left = node;

			else

				rb_parent(old)->rb_right = node;

		} else

			root->rb_node = node;

		rb_set_parent(old->rb_left, node);

		if (old->rb_right)

			rb_set_parent(old->rb_right, node);

		goto color;

	}

	parent = rb_parent(node);

	color = rb_color(node);

	if (child)

		rb_set_parent(child, parent);

	if (parent)

	{

		if (parent->rb_left == node)

			parent->rb_left = child;

		else

			parent->rb_right = child;

	}

	else

		root->rb_node = child;

 color:

	if (color == RB_BLACK)

		__rb_erase_color(child, parent, root);

}

/*

 * This function returns the first node (in sort order) of the tree.

 */

struct rb_node *rb_first(struct rb_root *root)

{

	struct rb_node	*n;

	n = root->rb_node;

	if (!n)

		return NULL;

	while (n->rb_left)

		n = n->rb_left;

	return n;

}

struct rb_node *rb_last(struct rb_root *root)

{

	struct rb_node	*n;

	n = root->rb_node;

	if (!n)

		return NULL;

	while (n->rb_right)

		n = n->rb_right;

	return n;

}

struct rb_node *rb_next(struct rb_node *node)

{

	struct rb_node *parent;

	if (rb_parent(node) == node)

		return NULL;

	/* If we have a right-hand child, go down and then left as far

	   as we can. */

	if (node->rb_right) {

		node = node->rb_right; 

		while (node->rb_left)

			node=node->rb_left;

		return node;

	}

	/* No right-hand children.  Everything down and left is

	   smaller than us, so any 'next' node must be in the general

	   direction of our parent. Go up the tree; any time the

	   ancestor is a right-hand child of its parent, keep going

	   up. First time it's a left-hand child of its parent, said

	   parent is our 'next' node. */

	while ((parent = rb_parent(node)) && node == parent->rb_right)

		node = parent;

	return parent;

}

struct rb_node *rb_prev(struct rb_node *node)

{

	struct rb_node *parent;

	if (rb_parent(node) == node)

		return NULL;

	/* If we have a left-hand child, go down and then right as far

	   as we can. */

	if (node->rb_left) {

		node = node->rb_left; 

		while (node->rb_right)

			node=node->rb_right;

		return node;

	}

	/* No left-hand children. Go up till we find an ancestor which

	   is a right-hand child of its parent */

	while ((parent = rb_parent(node)) && node == parent->rb_left)

		node = parent;

	return parent;

}

void rb_replace_node(struct rb_node *victim, struct rb_node *new,

		     struct rb_root *root)

{

	struct rb_node *parent = rb_parent(victim);

	/* Set the surrounding nodes to point to the replacement */

	if (parent) {

		if (victim == parent->rb_left)

			parent->rb_left = new;

		else

			parent->rb_right = new;

	} else {

		root->rb_node = new;

	}

	if (victim->rb_left)

		rb_set_parent(victim->rb_left, new);

	if (victim->rb_right)

		rb_set_parent(victim->rb_right, new);

	/* Copy the pointers/colour from the victim to the replacement */

	*new = *victim;

}