270 lines
8.4 KiB
C
270 lines
8.4 KiB
C
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/*
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* Copyright © 2017 Jason Ekstrand
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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#ifndef RB_TREE_H
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#define RB_TREE_H
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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/** A red-black tree node
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*
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* This struct represents a node in the red-black tree. This struct should
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* be embedded as a member in whatever structure you wish to put in the
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* tree.
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*/
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struct rb_node {
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/** Parent and color of this node
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*
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* The least significant bit represents the color and is est to 1 for
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* black and 0 for red. The other bits are the pointer to the parent
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* and that pointer can be retrieved by masking off the bottom bit and
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* casting to a pointer.
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*/
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uintptr_t parent;
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/** Left child of this node, null for a leaf */
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struct rb_node *left;
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/** Right child of this node, null for a leaf */
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struct rb_node *right;
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};
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/** Return the parent node of the given node or NULL if it is the root */
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static inline struct rb_node *
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rb_node_parent(struct rb_node *n)
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{
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return (struct rb_node *)(n->parent & ~1ull);
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}
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/** A red-black tree
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*
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* This struct represents the red-black tree itself. It is just a pointer
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* to the root node with no other metadata.
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*/
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struct rb_tree {
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struct rb_node *root;
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};
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/** Initialize a red-black tree */
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void rb_tree_init(struct rb_tree *T);
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/** Returns true if the red-black tree is empty */
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static inline bool
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rb_tree_is_empty(const struct rb_tree *T)
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{
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return T->root == NULL;
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}
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/** Retrieve the data structure containing a node
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*
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* \param type The type of the containing data structure
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*
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* \param node A pointer to a rb_node
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*
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* \param field The rb_node field in the containing data structure
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*/
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#define rb_node_data(type, node, field) \
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((type *)(((char *)(node)) - offsetof(type, field)))
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/** Insert a node into a tree at a particular location
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*
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* This function should probably not be used directly as it relies on the
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* caller to ensure that the parent node is correct. Use rb_tree_insert
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* instead.
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*
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* \param T The red-black tree into which to insert the new node
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*
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* \param parent The node in the tree that will be the parent of the
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* newly inserted node
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*
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* \param node The node to insert
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*
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* \param insert_left If true, the new node will be the left child of
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* \p parent, otherwise it will be the right child
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*/
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void rb_tree_insert_at(struct rb_tree *T, struct rb_node *parent,
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struct rb_node *node, bool insert_left);
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/** Insert a node into a tree
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*
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* \param T The red-black tree into which to insert the new node
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*
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* \param node The node to insert
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*
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* \param cmp A comparison function to use to order the nodes.
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*/
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static inline void
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rb_tree_insert(struct rb_tree *T, struct rb_node *node,
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int (*cmp)(const struct rb_node *, const struct rb_node *))
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{
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/* This function is declared inline in the hopes that the compiler can
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* optimize away the comparison function pointer call.
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*/
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struct rb_node *y = NULL;
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struct rb_node *x = T->root;
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bool left = false;
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while (x != NULL) {
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y = x;
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left = cmp(node, x) < 0;
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if (left)
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x = x->left;
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else
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x = x->right;
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}
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rb_tree_insert_at(T, y, node, left);
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}
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/** Remove a node from a tree
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*
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* \param T The red-black tree from which to remove the node
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*
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* \param node The node to remove
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*/
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void rb_tree_remove(struct rb_tree *T, struct rb_node *z);
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/** Search the tree for a node
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*
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* If a node with a matching key exists, the first matching node found will
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* be returned. If no matching node exists, NULL is returned.
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*
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* \param T The red-black tree to search
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*
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* \param key The key to search for
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*
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* \param cmp A comparison function to use to order the nodes
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*/
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static inline struct rb_node *
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rb_tree_search(struct rb_tree *T, const void *key,
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int (*cmp)(const struct rb_node *, const void *))
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{
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/* This function is declared inline in the hopes that the compiler can
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* optimize away the comparison function pointer call.
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*/
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struct rb_node *x = T->root;
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while (x != NULL) {
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int c = cmp(x, key);
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if (c < 0)
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x = x->right;
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else if (c > 0)
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x = x->left;
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else
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return x;
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}
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return x;
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}
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/** Sloppily search the tree for a node
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*
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* This function searches the tree for a given node. If a node with a
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* matching key exists, that first matching node found will be returned.
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* If no node with an exactly matching key exists, the node returned will
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* be either the right-most node comparing less than \p key or the
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* right-most node comparing greater than \p key. If the tree is empty,
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* NULL is returned.
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*
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* \param T The red-black tree to search
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*
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* \param key The key to search for
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*
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* \param cmp A comparison function to use to order the nodes
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*/
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static inline struct rb_node *
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rb_tree_search_sloppy(struct rb_tree *T, const void *key,
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int (*cmp)(const struct rb_node *, const void *))
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{
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/* This function is declared inline in the hopes that the compiler can
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* optimize away the comparison function pointer call.
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*/
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struct rb_node *y = NULL;
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struct rb_node *x = T->root;
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while (x != NULL) {
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y = x;
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int c = cmp(x, key);
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if (c < 0)
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x = x->right;
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else if (c > 0)
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x = x->left;
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else
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return x;
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}
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return y;
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}
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/** Get the first (left-most) node in the tree or NULL */
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struct rb_node *rb_tree_first(struct rb_tree *T);
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/** Get the last (right-most) node in the tree or NULL */
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struct rb_node *rb_tree_last(struct rb_tree *T);
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/** Get the next node (to the right) in the tree or NULL */
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struct rb_node *rb_node_next(struct rb_node *node);
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/** Get the next previous (to the left) in the tree or NULL */
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struct rb_node *rb_node_prev(struct rb_node *node);
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/** Iterate over the nodes in the tree
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*
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* \param type The type of the containing data structure
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*
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* \param node The variable name for current node in the iteration;
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* this will be declared as a pointer to \p type
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*
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* \param T The red-black tree
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*
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* \param field The rb_node field in containing data structure
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*/
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#define rb_tree_foreach(type, node, T, field) \
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for (type *node = rb_node_data(type, rb_tree_first(T), field); \
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&node->field != NULL; \
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node = rb_node_data(type, rb_node_next(&node->field), field))
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/** Iterate over the nodes in the tree in reverse
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*
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* \param type The type of the containing data structure
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*
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* \param node The variable name for current node in the iteration;
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* this will be declared as a pointer to \p type
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*
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* \param T The red-black tree
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*
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* \param field The rb_node field in containing data structure
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*/
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#define rb_tree_foreach_rev(type, node, T, field) \
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for (type *node = rb_node_data(type, rb_tree_last(T), field); \
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&node->field != NULL; \
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node = rb_node_data(type, rb_node_prev(&node->field), field))
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/** Validate a red-black tree
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*
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* This function walks the tree and validates that this is a valid red-
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* black tree. If anything is wrong, it will assert-fail.
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*/
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void rb_tree_validate(struct rb_tree *T);
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#endif /* RB_TREE_H */
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