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// Copyright © Tavian Barnes <tavianator@tavianator.com>
// SPDX-License-Identifier: 0BSD
#ifndef BFS_TRIE_H
#define BFS_TRIE_H
#include "config.h"
#include "list.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
/**
* A leaf of a trie.
*/
struct trie_leaf {
/** Linked list of leaves, in insertion order. */
struct link link;
/** An arbitrary value associated with this leaf. */
void *value;
/** The length of the key in bytes. */
size_t length;
/** The key itself, stored inline. */
char key[];
};
/**
* A trie that holds a set of fixed- or variable-length strings.
*/
struct trie {
/** Pointer to the root node/leaf. */
uintptr_t root;
/** Linked list of leaves. */
struct list leaves;
};
/**
* Initialize an empty trie.
*/
void trie_init(struct trie *trie);
/**
* Find the leaf for a string key.
*
* @param trie
* The trie to search.
* @param key
* The key to look up.
* @return
* The found leaf, or NULL if the key is not present.
*/
struct trie_leaf *trie_find_str(const struct trie *trie, const char *key);
/**
* Find the leaf for a fixed-size key.
*
* @param trie
* The trie to search.
* @param key
* The key to look up.
* @param length
* The length of the key in bytes.
* @return
* The found leaf, or NULL if the key is not present.
*/
struct trie_leaf *trie_find_mem(const struct trie *trie, const void *key, size_t length);
/**
* Find the shortest leaf that starts with a given key.
*
* @param trie
* The trie to search.
* @param key
* The key to look up.
* @return
* A leaf that starts with the given key, or NULL.
*/
struct trie_leaf *trie_find_postfix(const struct trie *trie, const char *key);
/**
* Find the leaf that is the longest prefix of the given key.
*
* @param trie
* The trie to search.
* @param key
* The key to look up.
* @return
* The longest prefix match for the given key, or NULL.
*/
struct trie_leaf *trie_find_prefix(const struct trie *trie, const char *key);
/**
* Insert a string key into the trie.
*
* @param trie
* The trie to modify.
* @param key
* The key to insert.
* @return
* The inserted leaf, or NULL on failure.
*/
struct trie_leaf *trie_insert_str(struct trie *trie, const char *key);
/**
* Insert a fixed-size key into the trie.
*
* @param trie
* The trie to modify.
* @param key
* The key to insert.
* @param length
* The length of the key in bytes.
* @return
* The inserted leaf, or NULL on failure.
*/
struct trie_leaf *trie_insert_mem(struct trie *trie, const void *key, size_t length);
/**
* Remove a leaf from a trie.
*
* @param trie
* The trie to modify.
* @param leaf
* The leaf to remove.
*/
void trie_remove(struct trie *trie, struct trie_leaf *leaf);
/**
* Destroy a trie and its contents.
*/
void trie_destroy(struct trie *trie);
/**
* Iterate over the leaves of a trie.
*/
#define TRIE_FOR_EACH(trie, leaf) \
LIST_FOR_EACH(&(trie)->leaves, struct trie_leaf, leaf)
#endif // BFS_TRIE_H
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