/*

  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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  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 = ext2fs_rb_parent(node);

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

    ext2fs_rb_set_parent(right->rb_left, node);

  right->rb_left = node;

  ext2fs_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;

  ext2fs_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 = ext2fs_rb_parent(node);

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

    ext2fs_rb_set_parent(left->rb_right, node);

  left->rb_right = node;

  ext2fs_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;

  ext2fs_rb_set_parent(node, left);

}

void ext2fs_rb_insert_color(struct rb_node *node, struct rb_root *root)

{

  struct rb_node *parent, *gparent;

  while ((parent = ext2fs_rb_parent(node)) && ext2fs_rb_is_red(parent))

  {

    gparent = ext2fs_rb_parent(parent);

    if (parent == gparent->rb_left)

    {

      {

        register struct rb_node *uncle = gparent->rb_right;

        if (uncle && ext2fs_rb_is_red(uncle))

        {

          ext2fs_rb_set_black(uncle);

          ext2fs_rb_set_black(parent);

          ext2fs_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;

      }

      ext2fs_rb_set_black(parent);

      ext2fs_rb_set_red(gparent);

      __rb_rotate_right(gparent, root);

    } else {

      {

        register struct rb_node *uncle = gparent->rb_left;

        if (uncle && ext2fs_rb_is_red(uncle))

        {

          ext2fs_rb_set_black(uncle);

          ext2fs_rb_set_black(parent);

          ext2fs_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;

      }

      ext2fs_rb_set_black(parent);

      ext2fs_rb_set_red(gparent);

      __rb_rotate_left(gparent, root);

    }

  }

  ext2fs_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 || ext2fs_rb_is_black(node)) && node != root->rb_node)

  {

    if (parent->rb_left == node)

    {

      other = parent->rb_right;

      if (ext2fs_rb_is_red(other))

      {

        ext2fs_rb_set_black(other);

        ext2fs_rb_set_red(parent);

        __rb_rotate_left(parent, root);

        other = parent->rb_right;

      }

      if ((!other->rb_left || ext2fs_rb_is_black(other->rb_left)) &&

          (!other->rb_right || ext2fs_rb_is_black(other->rb_right)))

      {

        ext2fs_rb_set_red(other);

        node = parent;

        parent = ext2fs_rb_parent(node);

      }

      else

      {

        if (!other->rb_right || ext2fs_rb_is_black(other->rb_right))

        {

          ext2fs_rb_set_black(other->rb_left);

          ext2fs_rb_set_red(other);

          __rb_rotate_right(other, root);

          other = parent->rb_right;

        }

        ext2fs_rb_set_color(other, ext2fs_rb_color(parent));

        ext2fs_rb_set_black(parent);

        ext2fs_rb_set_black(other->rb_right);

        __rb_rotate_left(parent, root);

        node = root->rb_node;

        break;

      }

    }

    else

    {

      other = parent->rb_left;

      if (ext2fs_rb_is_red(other))

      {

        ext2fs_rb_set_black(other);

        ext2fs_rb_set_red(parent);

        __rb_rotate_right(parent, root);

        other = parent->rb_left;

      }

      if ((!other->rb_left || ext2fs_rb_is_black(other->rb_left)) &&

          (!other->rb_right || ext2fs_rb_is_black(other->rb_right)))

      {

        ext2fs_rb_set_red(other);

        node = parent;

        parent = ext2fs_rb_parent(node);

      }

      else

      {

        if (!other->rb_left || ext2fs_rb_is_black(other->rb_left))

        {

          ext2fs_rb_set_black(other->rb_right);

          ext2fs_rb_set_red(other);

          __rb_rotate_left(other, root);

          other = parent->rb_left;

        }

        ext2fs_rb_set_color(other, ext2fs_rb_color(parent));

        ext2fs_rb_set_black(parent);

        ext2fs_rb_set_black(other->rb_left);

        __rb_rotate_right(parent, root);

        node = root->rb_node;

        break;

      }

    }

  }

  if (node)

    ext2fs_rb_set_black(node);

}

void ext2fs_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;

    if (ext2fs_rb_parent(old)) {

      if (ext2fs_rb_parent(old)->rb_left == old)

        ext2fs_rb_parent(old)->rb_left = node;

      else

        ext2fs_rb_parent(old)->rb_right = node;

    } else

      root->rb_node = node;

    child = node->rb_right;

    parent = ext2fs_rb_parent(node);

    color = ext2fs_rb_color(node);

    if (parent == old) {

      parent = node;

    } else {

      if (child)

        ext2fs_rb_set_parent(child, parent);

      parent->rb_left = child;

      node->rb_right = old->rb_right;

      ext2fs_rb_set_parent(old->rb_right, node);

    }

    node->rb_parent_color = old->rb_parent_color;

    node->rb_left = old->rb_left;

    ext2fs_rb_set_parent(old->rb_left, node);

    goto color;

  }

  parent = ext2fs_rb_parent(node);

  color = ext2fs_rb_color(node);

  if (child)

    ext2fs_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 *ext2fs_rb_first(const 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 *ext2fs_rb_last(const 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 *ext2fs_rb_next(struct rb_node *node)

{

  struct rb_node *parent;

  if (ext2fs_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 (struct rb_node *)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 = ext2fs_rb_parent(node)) && node == parent->rb_right)

    node = parent;

  return parent;

}

struct rb_node *ext2fs_rb_prev(struct rb_node *node)

{

  struct rb_node *parent;

  if (ext2fs_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 (struct rb_node *)node;

  }

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

     is a right-hand child of its parent */

  while ((parent = ext2fs_rb_parent(node)) && node == parent->rb_left)

    node = parent;

  return parent;

}

void ext2fs_rb_replace_node(struct rb_node *victim, struct rb_node *new,

        struct rb_root *root)

{

  struct rb_node *parent = ext2fs_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)

    ext2fs_rb_set_parent(victim->rb_left, new);

  if (victim->rb_right)

    ext2fs_rb_set_parent(victim->rb_right, new);

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

  *new = *victim;

}