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Diffstat (limited to 'src/util/rb_tree.h')
| -rw-r--r-- | src/util/rb_tree.h | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/src/util/rb_tree.h b/src/util/rb_tree.h new file mode 100644 index 00000000000..e8750b32d0e --- /dev/null +++ b/src/util/rb_tree.h @@ -0,0 +1,269 @@ +/* + * Copyright © 2017 Jason Ekstrand + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + * DEALINGS IN THE SOFTWARE. + */ + +#ifndef RB_TREE_H +#define RB_TREE_H + +#include <stdbool.h> +#include <stddef.h> +#include <stdint.h> +#include <stdlib.h> + +/** A red-black tree node + * + * This struct represents a node in the red-black tree. This struct should + * be embedded as a member in whatever structure you wish to put in the + * tree. + */ +struct rb_node { + /** Parent and color of this node + * + * The least significant bit represents the color and is est to 1 for + * black and 0 for red. The other bits are the pointer to the parent + * and that pointer can be retrieved by masking off the bottom bit and + * casting to a pointer. + */ + uintptr_t parent; + + /** Left child of this node, null for a leaf */ + struct rb_node *left; + + /** Right child of this node, null for a leaf */ + struct rb_node *right; +}; + +/** Return the parent node of the given node or NULL if it is the root */ +static inline struct rb_node * +rb_node_parent(struct rb_node *n) +{ + return (struct rb_node *)(n->parent & ~1ull); +} + +/** A red-black tree + * + * This struct represents the red-black tree itself. It is just a pointer + * to the root node with no other metadata. + */ +struct rb_tree { + struct rb_node *root; +}; + +/** Initialize a red-black tree */ +void rb_tree_init(struct rb_tree *T); + +/** Returns true if the red-black tree is empty */ +static inline bool +rb_tree_is_empty(const struct rb_tree *T) +{ + return T->root == NULL; +} + +/** Retrieve the data structure containing a node + * + * \param type The type of the containing data structure + * + * \param node A pointer to a rb_node + * + * \param field The rb_node field in the containing data structure + */ +#define rb_node_data(type, node, field) \ + ((type *)(((char *)(node)) - offsetof(type, field))) + +/** Insert a node into a tree at a particular location + * + * This function should probably not be used directly as it relies on the + * caller to ensure that the parent node is correct. Use rb_tree_insert + * instead. + * + * \param T The red-black tree into which to insert the new node + * + * \param parent The node in the tree that will be the parent of the + * newly inserted node + * + * \param node The node to insert + * + * \param insert_left If true, the new node will be the left child of + * \p parent, otherwise it will be the right child + */ +void rb_tree_insert_at(struct rb_tree *T, struct rb_node *parent, + struct rb_node *node, bool insert_left); + +/** Insert a node into a tree + * + * \param T The red-black tree into which to insert the new node + * + * \param node The node to insert + * + * \param cmp A comparison function to use to order the nodes. + */ +static inline void +rb_tree_insert(struct rb_tree *T, struct rb_node *node, + int (*cmp)(const struct rb_node *, const struct rb_node *)) +{ + /* This function is declared inline in the hopes that the compiler can + * optimize away the comparison function pointer call. + */ + struct rb_node *y = NULL; + struct rb_node *x = T->root; + bool left = false; + while (x != NULL) { + y = x; + left = cmp(node, x) < 0; + if (left) + x = x->left; + else + x = x->right; + } + + rb_tree_insert_at(T, y, node, left); +} + +/** Remove a node from a tree + * + * \param T The red-black tree from which to remove the node + * + * \param node The node to remove + */ +void rb_tree_remove(struct rb_tree *T, struct rb_node *z); + +/** Search the tree for a node + * + * If a node with a matching key exists, the first matching node found will + * be returned. If no matching node exists, NULL is returned. + * + * \param T The red-black tree to search + * + * \param key The key to search for + * + * \param cmp A comparison function to use to order the nodes + */ +static inline struct rb_node * +rb_tree_search(struct rb_tree *T, const void *key, + int (*cmp)(const struct rb_node *, const void *)) +{ + /* This function is declared inline in the hopes that the compiler can + * optimize away the comparison function pointer call. + */ + struct rb_node *x = T->root; + while (x != NULL) { + int c = cmp(x, key); + if (c < 0) + x = x->right; + else if (c > 0) + x = x->left; + else + return x; + } + + return x; +} + +/** Sloppily search the tree for a node + * + * This function searches the tree for a given node. If a node with a + * matching key exists, that first matching node found will be returned. + * If no node with an exactly matching key exists, the node returned will + * be either the right-most node comparing less than \p key or the + * right-most node comparing greater than \p key. If the tree is empty, + * NULL is returned. + * + * \param T The red-black tree to search + * + * \param key The key to search for + * + * \param cmp A comparison function to use to order the nodes + */ +static inline struct rb_node * +rb_tree_search_sloppy(struct rb_tree *T, const void *key, + int (*cmp)(const struct rb_node *, const void *)) +{ + /* This function is declared inline in the hopes that the compiler can + * optimize away the comparison function pointer call. + */ + struct rb_node *y = NULL; + struct rb_node *x = T->root; + while (x != NULL) { + y = x; + int c = cmp(x, key); + if (c < 0) + x = x->right; + else if (c > 0) + x = x->left; + else + return x; + } + + return y; +} + +/** Get the first (left-most) node in the tree or NULL */ +struct rb_node *rb_tree_first(struct rb_tree *T); + +/** Get the last (right-most) node in the tree or NULL */ +struct rb_node *rb_tree_last(struct rb_tree *T); + +/** Get the next node (to the right) in the tree or NULL */ +struct rb_node *rb_node_next(struct rb_node *node); + +/** Get the next previous (to the left) in the tree or NULL */ +struct rb_node *rb_node_prev(struct rb_node *node); + +/** Iterate over the nodes in the tree + * + * \param type The type of the containing data structure + * + * \param node The variable name for current node in the iteration; + * this will be declared as a pointer to \p type + * + * \param T The red-black tree + * + * \param field The rb_node field in containing data structure + */ +#define rb_tree_foreach(type, node, T, field) \ + for (type *node = rb_node_data(type, rb_tree_first(T), field); \ + &node->field != NULL; \ + node = rb_node_data(type, rb_node_next(&node->field), field)) + +/** Iterate over the nodes in the tree in reverse + * + * \param type The type of the containing data structure + * + * \param node The variable name for current node in the iteration; + * this will be declared as a pointer to \p type + * + * \param T The red-black tree + * + * \param field The rb_node field in containing data structure + */ +#define rb_tree_foreach_rev(type, node, T, field) \ + for (type *node = rb_node_data(type, rb_tree_last(T), field); \ + &node->field != NULL; \ + node = rb_node_data(type, rb_node_prev(&node->field), field)) + +/** Validate a red-black tree + * + * This function walks the tree and validates that this is a valid red- + * black tree. If anything is wrong, it will assert-fail. + */ +void rb_tree_validate(struct rb_tree *T); + +#endif /* RB_TREE_H */ |