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249 lines
7.5 KiB
249 lines
7.5 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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(C) 2012 Michel Lespinasse <walken@google.com> |
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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/include/linux/rbtree_augmented.h |
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*/ |
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#ifndef _LINUX_RBTREE_AUGMENTED_H |
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#define _LINUX_RBTREE_AUGMENTED_H |
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#include <linux/compiler.h> |
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#include <linux/rbtree.h> |
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/* |
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* Please note - only struct rb_augment_callbacks and the prototypes for |
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* rb_insert_augmented() and rb_erase_augmented() are intended to be public. |
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* The rest are implementation details you are not expected to depend on. |
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* |
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* See Documentation/rbtree.txt for documentation and samples. |
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*/ |
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struct rb_augment_callbacks { |
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void (*propagate)(struct rb_node *node, struct rb_node *stop); |
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void (*copy)(struct rb_node *old, struct rb_node *new); |
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void (*rotate)(struct rb_node *old, struct rb_node *new); |
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}; |
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extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, |
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void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); |
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/* |
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* Fixup the rbtree and update the augmented information when rebalancing. |
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* |
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* On insertion, the user must update the augmented information on the path |
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* leading to the inserted node, then call rb_link_node() as usual and |
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* rb_augment_inserted() instead of the usual rb_insert_color() call. |
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* If rb_augment_inserted() rebalances the rbtree, it will callback into |
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* a user provided function to update the augmented information on the |
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* affected subtrees. |
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*/ |
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static inline void |
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rb_insert_augmented(struct rb_node *node, struct rb_root *root, |
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const struct rb_augment_callbacks *augment) |
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{ |
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__rb_insert_augmented(node, root, augment->rotate); |
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} |
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#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \ |
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rbtype, rbaugmented, rbcompute) \ |
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static inline void \ |
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rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \ |
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{ \ |
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while (rb != stop) { \ |
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rbstruct *node = rb_entry(rb, rbstruct, rbfield); \ |
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rbtype augmented = rbcompute(node); \ |
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if (node->rbaugmented == augmented) \ |
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break; \ |
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node->rbaugmented = augmented; \ |
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rb = rb_parent(&node->rbfield); \ |
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} \ |
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} \ |
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static inline void \ |
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rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \ |
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{ \ |
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rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ |
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rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ |
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new->rbaugmented = old->rbaugmented; \ |
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} \ |
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static void \ |
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rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \ |
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{ \ |
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rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ |
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rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ |
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new->rbaugmented = old->rbaugmented; \ |
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old->rbaugmented = rbcompute(old); \ |
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} \ |
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rbstatic const struct rb_augment_callbacks rbname = { \ |
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rbname ## _propagate, rbname ## _copy, rbname ## _rotate \ |
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}; |
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#define RB_RED 0 |
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#define RB_BLACK 1 |
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#define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) |
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#define __rb_color(pc) ((pc) & 1) |
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#define __rb_is_black(pc) __rb_color(pc) |
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#define __rb_is_red(pc) (!__rb_color(pc)) |
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#define rb_color(rb) __rb_color((rb)->__rb_parent_color) |
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#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) |
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#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) |
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static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) |
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{ |
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rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; |
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} |
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static inline void rb_set_parent_color(struct rb_node *rb, |
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struct rb_node *p, int color) |
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{ |
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rb->__rb_parent_color = (unsigned long)p | color; |
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} |
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static inline void |
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__rb_change_child(struct rb_node *old, struct rb_node *new, |
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struct rb_node *parent, struct rb_root *root) |
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{ |
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if (parent) { |
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if (parent->rb_left == old) |
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WRITE_ONCE(parent->rb_left, new); |
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else |
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WRITE_ONCE(parent->rb_right, new); |
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} else |
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WRITE_ONCE(root->rb_node, new); |
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} |
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extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, |
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void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); |
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static __always_inline struct rb_node * |
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__rb_erase_augmented(struct rb_node *node, struct rb_root *root, |
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const struct rb_augment_callbacks *augment) |
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{ |
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struct rb_node *child = node->rb_right; |
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struct rb_node *tmp = node->rb_left; |
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struct rb_node *parent, *rebalance; |
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unsigned long pc; |
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if (!tmp) { |
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/* |
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* Case 1: node to erase has no more than 1 child (easy!) |
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* |
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* Note that if there is one child it must be red due to 5) |
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* and node must be black due to 4). We adjust colors locally |
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* so as to bypass __rb_erase_color() later on. |
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*/ |
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pc = node->__rb_parent_color; |
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parent = __rb_parent(pc); |
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__rb_change_child(node, child, parent, root); |
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if (child) { |
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child->__rb_parent_color = pc; |
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rebalance = NULL; |
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} else |
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rebalance = __rb_is_black(pc) ? parent : NULL; |
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tmp = parent; |
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} else if (!child) { |
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/* Still case 1, but this time the child is node->rb_left */ |
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tmp->__rb_parent_color = pc = node->__rb_parent_color; |
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parent = __rb_parent(pc); |
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__rb_change_child(node, tmp, parent, root); |
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rebalance = NULL; |
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tmp = parent; |
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} else { |
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struct rb_node *successor = child, *child2; |
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tmp = child->rb_left; |
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if (!tmp) { |
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/* |
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* Case 2: node's successor is its right child |
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* |
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* (n) (s) |
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* / \ / \ |
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* (x) (s) -> (x) (c) |
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* \ |
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* (c) |
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*/ |
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parent = successor; |
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child2 = successor->rb_right; |
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augment->copy(node, successor); |
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} else { |
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/* |
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* Case 3: node's successor is leftmost under |
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* node's right child subtree |
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* |
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* (n) (s) |
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* / \ / \ |
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* (x) (y) -> (x) (y) |
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* / / |
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* (p) (p) |
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* / / |
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* (s) (c) |
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* \ |
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* (c) |
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*/ |
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do { |
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parent = successor; |
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successor = tmp; |
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tmp = tmp->rb_left; |
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} while (tmp); |
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child2 = successor->rb_right; |
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WRITE_ONCE(parent->rb_left, child2); |
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WRITE_ONCE(successor->rb_right, child); |
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rb_set_parent(child, successor); |
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augment->copy(node, successor); |
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augment->propagate(parent, successor); |
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} |
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tmp = node->rb_left; |
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WRITE_ONCE(successor->rb_left, tmp); |
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rb_set_parent(tmp, successor); |
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pc = node->__rb_parent_color; |
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tmp = __rb_parent(pc); |
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__rb_change_child(node, successor, tmp, root); |
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if (child2) { |
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successor->__rb_parent_color = pc; |
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rb_set_parent_color(child2, parent, RB_BLACK); |
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rebalance = NULL; |
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} else { |
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unsigned long pc2 = successor->__rb_parent_color; |
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successor->__rb_parent_color = pc; |
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rebalance = __rb_is_black(pc2) ? parent : NULL; |
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} |
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tmp = successor; |
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} |
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augment->propagate(tmp, NULL); |
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return rebalance; |
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} |
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static __always_inline void |
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rb_erase_augmented(struct rb_node *node, struct rb_root *root, |
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const struct rb_augment_callbacks *augment) |
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{ |
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struct rb_node *rebalance = __rb_erase_augmented(node, root, augment); |
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if (rebalance) |
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__rb_erase_color(rebalance, root, augment->rotate); |
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} |
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#endif /* _LINUX_RBTREE_AUGMENTED_H */
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