rbtree.h

Red Black Trees This file is come from the Linux Kernel.

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <[e-mail]>
  
  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

  To use rbtrees you'll have to implement your own insert and search cores.
  This will avoid us to use callbacks and to drop drammatically performances.
  I know it's not the cleaner way,  but in C (not in C++) to get
  performances and genericity...

  Some example of insert and search follows here. The search is a plain
  normal search over an ordered tree. The insert instead must be implemented
  int two steps: as first thing the code must insert the element in
  order as a red leaf in the tree, then the support library function
  rb_insert_color() must be called. Such function will do the
  not trivial work to rebalance the rbtree if necessary.

-----------------------------------------------------------------------
static inline struct page * rb_search_page_cache(struct inode * inode,
						 unsigned long offset)
{
	rb_node_t * n = inode->i_rb_page_cache.rb_node;
	struct page * page;

	while (n)
	{
		page = rb_entry(n, struct page, rb_page_cache);

		if (offset < page->offset)
			n = n->rb_left;
		else if (offset > page->offset)
			n = n->rb_right;
		else
			return page;
	}
	return NULL;
}

static inline struct page * __rb_insert_page_cache(struct inode * inode,
						   unsigned long offset,
						   rb_node_t * node)
{
	rb_node_t ** p = &inode->i_rb_page_cache.rb_node;
	rb_node_t * parent = NULL;
	struct page * page;

	while (*p)
	{
		parent = *p;
		page = rb_entry(parent, struct page, rb_page_cache);

		if (offset < page->offset)
			p = &(*p)->rb_left;
		else if (offset > page->offset)
			p = &(*p)->rb_right;
		else
			return page;
	}

	rb_link_node(node, parent, p);

	return NULL;
}

static inline struct page * rb_insert_page_cache(struct inode * inode,
						 unsigned long offset,
						 rb_node_t * node)
{
	struct page * ret;
	if ((ret = __rb_insert_page_cache(inode, offset, node)))
		goto out;
	rb_insert_color(node, &inode->i_rb_page_cache);
 out:
	return ret;
}
-----------------------------------------------------------------------
teawater:This file is come from the Linux Kernel.
*/

#ifndef	_LINUX_RBTREE_H
#define	_LINUX_RBTREE_H

typedef struct rb_node_s {
	struct rb_node_s * rb_parent;
	int rb_color;
#define	RB_RED		0
#define	RB_BLACK	1
	struct rb_node_s * rb_right;
	struct rb_node_s * rb_left;
}rb_node_t;

typedef struct rb_root_s {
	struct rb_node_s * rb_node;
}rb_root_t;

#define RB_ROOT				(rb_root_t){ NULL, }
#define	rb_entry(ptr, type, member)	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))


static inline void
rb_link_node(rb_node_t * node, rb_node_t * parent, rb_node_t ** rb_link)
{
	node->rb_parent = parent;
	node->rb_color = RB_RED;
	node->rb_left = node->rb_right = NULL;

	*rb_link = node;
}

static void
__rb_rotate_left(rb_node_t * node, rb_root_t * root)
{
	rb_node_t * right = node->rb_right;

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

	if ((right->rb_parent = node->rb_parent))
	{
		if (node == node->rb_parent->rb_left)
			node->rb_parent->rb_left = right;
		else
			node->rb_parent->rb_right = right;
	}
	else
		root->rb_node = right;
	node->rb_parent = right;
}

static void
__rb_rotate_right(rb_node_t * node, rb_root_t * root)
{
	rb_node_t * left = node->rb_left;

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

	if ((left->rb_parent = node->rb_parent))
	{
		if (node == node->rb_parent->rb_right)
			node->rb_parent->rb_right = left;
		else
			node->rb_parent->rb_left = left;
	}
	else
		root->rb_node = left;
	node->rb_parent = left;
}

static void
rb_insert_color(rb_node_t * node, rb_root_t * root)
{
	rb_node_t * parent, * gparent;

	while ((parent = node->rb_parent) && parent->rb_color == RB_RED)
	{
		gparent = parent->rb_parent;

		if (parent == gparent->rb_left)
		{
			{
				register rb_node_t * uncle = gparent->rb_right;
				if (uncle && uncle->rb_color == RB_RED)
				{
					uncle->rb_color = RB_BLACK;
					parent->rb_color = RB_BLACK;
					gparent->rb_color = RB_RED;
					node = gparent;
					continue;
				}
			}

			if (parent->rb_right == node)
			{
				register rb_node_t * tmp;
				__rb_rotate_left(parent, root);
				tmp = parent;
				parent = node;
				node = tmp;
			}

			parent->rb_color = RB_BLACK;
			gparent->rb_color = RB_RED;
			__rb_rotate_right(gparent, root);
		} else {
			{
				register rb_node_t * uncle = gparent->rb_left;
				if (uncle && uncle->rb_color == RB_RED)
				{
					uncle->rb_color = RB_BLACK;
					parent->rb_color = RB_BLACK;
					gparent->rb_color = RB_RED;
					node = gparent;
					continue;
				}
			}

			if (parent->rb_left == node)
			{
				register rb_node_t * tmp;
				__rb_rotate_right(parent, root);
				tmp = parent;
				parent = node;
				node = tmp;
			}

			parent->rb_color = RB_BLACK;
			gparent->rb_color = RB_RED;
			__rb_rotate_left(gparent, root);
		}
	}

	root->rb_node->rb_color = RB_BLACK;
}

static void
__rb_erase_color(rb_node_t * node, rb_node_t * parent, rb_root_t * root)
{
	rb_node_t * other;

	while ((!node || node->rb_color == RB_BLACK) && node != root->rb_node)
	{
		if (parent->rb_left == node)
		{
			other = parent->rb_right;
			if (other->rb_color == RB_RED)
			{
				other->rb_color = RB_BLACK;
				parent->rb_color = RB_RED;
				__rb_rotate_left(parent, root);
				other = parent->rb_right;
			}
			if ((!other->rb_left ||
			     other->rb_left->rb_color == RB_BLACK)
			    && (!other->rb_right ||
				other->rb_right->rb_color == RB_BLACK))
			{
				other->rb_color = RB_RED;
				node = parent;
				parent = node->rb_parent;
			}
			else
			{
				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;
					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;
				__rb_rotate_left(parent, root);
				node = root->rb_node;
				break;
			}
		}
		else
		{
			other = parent->rb_left;
			if (other->rb_color == RB_RED)
			{
				other->rb_color = RB_BLACK;
				parent->rb_color = RB_RED;
				__rb_rotate_right(parent, root);
				other = parent->rb_left;
			}
			if ((!other->rb_left ||
			     other->rb_left->rb_color == RB_BLACK)
			    && (!other->rb_right ||
				other->rb_right->rb_color == RB_BLACK))
			{
				other->rb_color = RB_RED;
				node = parent;
				parent = node->rb_parent;
			}
			else
			{
				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;
					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;
				__rb_rotate_right(parent, root);
				node = root->rb_node;
				break;
			}
		}
	}
	if (node)
		node->rb_color = RB_BLACK;
}

static void
rb_erase(rb_node_t * node, rb_root_t * root)
{
	rb_node_t * child, * parent;
	int color;

	if (!node->rb_left)
		child = node->rb_right;
	else if (!node->rb_right)
		child = node->rb_left;
	else
	{
		rb_node_t * old = node, * left;

		node = node->rb_right;
		while ((left = node->rb_left))
			node = left;
		child = node->rb_right;
		parent = node->rb_parent;
		color = node->rb_color;

		if (child)
			child->rb_parent = parent;
		if (parent)
		{
			if (parent->rb_left == node)
				parent->rb_left = child;
			else
				parent->rb_right = child;
		}
		else
			root->rb_node = child;

		if (node->rb_parent == old)
			parent = node;
		node->rb_parent = old->rb_parent;
		node->rb_color = old->rb_color;
		node->rb_right = old->rb_right;
		node->rb_left = old->rb_left;

		if (old->rb_parent)
		{
			if (old->rb_parent->rb_left == old)
				old->rb_parent->rb_left = node;
			else
				old->rb_parent->rb_right = node;
		} else
			root->rb_node = node;

		old->rb_left->rb_parent = node;
		if (old->rb_right)
			old->rb_right->rb_parent = node;
		goto color;
	}

	parent = node->rb_parent;
	color = node->rb_color;

	if (child)
		child->rb_parent = 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);
}

#endif	/* _LINUX_RBTREE_H */