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389 lines
8.4 KiB
389 lines
8.4 KiB
/* |
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Red Black Trees |
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(C) 1999 Andrea Arcangeli <andrea@suse.de> |
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(C) 2002 David Woodhouse <dwmw2@infradead.org> |
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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linux/lib/rbtree.c |
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*/ |
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#include "rbtree.h" |
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static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) |
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{ |
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struct rb_node *right = node->rb_right; |
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struct rb_node *parent = rb_parent(node); |
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if ((node->rb_right = right->rb_left)) |
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rb_set_parent(right->rb_left, node); |
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right->rb_left = node; |
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rb_set_parent(right, parent); |
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if (parent) |
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{ |
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if (node == parent->rb_left) |
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parent->rb_left = right; |
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else |
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parent->rb_right = right; |
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} |
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else |
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root->rb_node = right; |
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rb_set_parent(node, right); |
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} |
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static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) |
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{ |
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struct rb_node *left = node->rb_left; |
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struct rb_node *parent = rb_parent(node); |
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if ((node->rb_left = left->rb_right)) |
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rb_set_parent(left->rb_right, node); |
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left->rb_right = node; |
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rb_set_parent(left, parent); |
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if (parent) |
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{ |
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if (node == parent->rb_right) |
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parent->rb_right = left; |
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else |
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parent->rb_left = left; |
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} |
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else |
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root->rb_node = left; |
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rb_set_parent(node, left); |
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} |
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void rb_insert_color(struct rb_node *node, struct rb_root *root) |
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{ |
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struct rb_node *parent, *gparent; |
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while ((parent = rb_parent(node)) && rb_is_red(parent)) |
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{ |
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gparent = rb_parent(parent); |
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if (parent == gparent->rb_left) |
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{ |
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{ |
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register struct rb_node *uncle = gparent->rb_right; |
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if (uncle && rb_is_red(uncle)) |
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{ |
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rb_set_black(uncle); |
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rb_set_black(parent); |
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rb_set_red(gparent); |
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node = gparent; |
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continue; |
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} |
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} |
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if (parent->rb_right == node) |
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{ |
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register struct rb_node *tmp; |
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__rb_rotate_left(parent, root); |
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tmp = parent; |
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parent = node; |
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node = tmp; |
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} |
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rb_set_black(parent); |
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rb_set_red(gparent); |
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__rb_rotate_right(gparent, root); |
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} else { |
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{ |
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register struct rb_node *uncle = gparent->rb_left; |
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if (uncle && rb_is_red(uncle)) |
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{ |
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rb_set_black(uncle); |
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rb_set_black(parent); |
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rb_set_red(gparent); |
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node = gparent; |
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continue; |
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} |
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} |
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if (parent->rb_left == node) |
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{ |
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register struct rb_node *tmp; |
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__rb_rotate_right(parent, root); |
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tmp = parent; |
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parent = node; |
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node = tmp; |
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} |
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rb_set_black(parent); |
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rb_set_red(gparent); |
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__rb_rotate_left(gparent, root); |
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} |
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} |
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rb_set_black(root->rb_node); |
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} |
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static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, |
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struct rb_root *root) |
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{ |
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struct rb_node *other; |
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while ((!node || rb_is_black(node)) && node != root->rb_node) |
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{ |
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if (parent->rb_left == node) |
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{ |
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other = parent->rb_right; |
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if (rb_is_red(other)) |
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{ |
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rb_set_black(other); |
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rb_set_red(parent); |
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__rb_rotate_left(parent, root); |
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other = parent->rb_right; |
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} |
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if ((!other->rb_left || rb_is_black(other->rb_left)) && |
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(!other->rb_right || rb_is_black(other->rb_right))) |
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{ |
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rb_set_red(other); |
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node = parent; |
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parent = rb_parent(node); |
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} |
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else |
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{ |
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if (!other->rb_right || rb_is_black(other->rb_right)) |
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{ |
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struct rb_node *o_left; |
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if ((o_left = other->rb_left)) |
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rb_set_black(o_left); |
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rb_set_red(other); |
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__rb_rotate_right(other, root); |
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other = parent->rb_right; |
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} |
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rb_set_color(other, rb_color(parent)); |
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rb_set_black(parent); |
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if (other->rb_right) |
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rb_set_black(other->rb_right); |
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__rb_rotate_left(parent, root); |
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node = root->rb_node; |
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break; |
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} |
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} |
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else |
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{ |
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other = parent->rb_left; |
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if (rb_is_red(other)) |
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{ |
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rb_set_black(other); |
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rb_set_red(parent); |
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__rb_rotate_right(parent, root); |
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other = parent->rb_left; |
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} |
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if ((!other->rb_left || rb_is_black(other->rb_left)) && |
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(!other->rb_right || rb_is_black(other->rb_right))) |
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{ |
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rb_set_red(other); |
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node = parent; |
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parent = rb_parent(node); |
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} |
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else |
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{ |
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if (!other->rb_left || rb_is_black(other->rb_left)) |
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{ |
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register struct rb_node *o_right; |
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if ((o_right = other->rb_right)) |
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rb_set_black(o_right); |
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rb_set_red(other); |
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__rb_rotate_left(other, root); |
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other = parent->rb_left; |
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} |
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rb_set_color(other, rb_color(parent)); |
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rb_set_black(parent); |
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if (other->rb_left) |
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rb_set_black(other->rb_left); |
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__rb_rotate_right(parent, root); |
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node = root->rb_node; |
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break; |
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} |
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} |
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} |
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if (node) |
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rb_set_black(node); |
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} |
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void rb_erase(struct rb_node *node, struct rb_root *root) |
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{ |
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struct rb_node *child, *parent; |
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int color; |
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if (!node->rb_left) |
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child = node->rb_right; |
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else if (!node->rb_right) |
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child = node->rb_left; |
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else |
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{ |
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struct rb_node *old = node, *left; |
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node = node->rb_right; |
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while ((left = node->rb_left) != NULL) |
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node = left; |
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child = node->rb_right; |
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parent = rb_parent(node); |
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color = rb_color(node); |
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if (child) |
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rb_set_parent(child, parent); |
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if (parent == old) { |
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parent->rb_right = child; |
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parent = node; |
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} else |
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parent->rb_left = child; |
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node->rb_parent_color = old->rb_parent_color; |
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node->rb_right = old->rb_right; |
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node->rb_left = old->rb_left; |
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if (rb_parent(old)) |
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{ |
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if (rb_parent(old)->rb_left == old) |
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rb_parent(old)->rb_left = node; |
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else |
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rb_parent(old)->rb_right = node; |
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} else |
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root->rb_node = node; |
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rb_set_parent(old->rb_left, node); |
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if (old->rb_right) |
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rb_set_parent(old->rb_right, node); |
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goto color; |
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} |
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parent = rb_parent(node); |
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color = rb_color(node); |
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if (child) |
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rb_set_parent(child, parent); |
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if (parent) |
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{ |
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if (parent->rb_left == node) |
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parent->rb_left = child; |
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else |
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parent->rb_right = child; |
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} |
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else |
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root->rb_node = child; |
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color: |
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if (color == RB_BLACK) |
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__rb_erase_color(child, parent, root); |
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} |
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/* |
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* This function returns the first node (in sort order) of the tree. |
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*/ |
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struct rb_node *rb_first(struct rb_root *root) |
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{ |
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struct rb_node *n; |
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n = root->rb_node; |
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if (!n) |
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return NULL; |
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while (n->rb_left) |
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n = n->rb_left; |
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return n; |
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} |
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struct rb_node *rb_last(struct rb_root *root) |
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{ |
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struct rb_node *n; |
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n = root->rb_node; |
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if (!n) |
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return NULL; |
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while (n->rb_right) |
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n = n->rb_right; |
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return n; |
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} |
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struct rb_node *rb_next(struct rb_node *node) |
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{ |
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struct rb_node *parent; |
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if (rb_parent(node) == node) |
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return NULL; |
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/* If we have a right-hand child, go down and then left as far |
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as we can. */ |
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if (node->rb_right) { |
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node = node->rb_right; |
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while (node->rb_left) |
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node=node->rb_left; |
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return node; |
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} |
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/* No right-hand children. Everything down and left is |
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smaller than us, so any 'next' node must be in the general |
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direction of our parent. Go up the tree; any time the |
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ancestor is a right-hand child of its parent, keep going |
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up. First time it's a left-hand child of its parent, said |
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parent is our 'next' node. */ |
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while ((parent = rb_parent(node)) && node == parent->rb_right) |
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node = parent; |
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return parent; |
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} |
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struct rb_node *rb_prev(struct rb_node *node) |
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{ |
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struct rb_node *parent; |
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if (rb_parent(node) == node) |
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return NULL; |
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/* If we have a left-hand child, go down and then right as far |
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as we can. */ |
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if (node->rb_left) { |
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node = node->rb_left; |
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while (node->rb_right) |
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node=node->rb_right; |
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return node; |
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} |
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/* No left-hand children. Go up till we find an ancestor which |
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is a right-hand child of its parent */ |
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while ((parent = rb_parent(node)) && node == parent->rb_left) |
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node = parent; |
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return parent; |
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} |
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void rb_replace_node(struct rb_node *victim, struct rb_node *new, |
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struct rb_root *root) |
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{ |
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struct rb_node *parent = rb_parent(victim); |
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/* Set the surrounding nodes to point to the replacement */ |
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if (parent) { |
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if (victim == parent->rb_left) |
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parent->rb_left = new; |
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else |
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parent->rb_right = new; |
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} else { |
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root->rb_node = new; |
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} |
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if (victim->rb_left) |
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rb_set_parent(victim->rb_left, new); |
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if (victim->rb_right) |
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rb_set_parent(victim->rb_right, new); |
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/* Copy the pointers/colour from the victim to the replacement */ |
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*new = *victim; |
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}
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