1 files changed, 147 insertions, 0 deletions
diff --git a/src/trie.h b/src/trie.h
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+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#ifndef BFS_TRIE_H
+#define BFS_TRIE_H
+
+#include "alloc.h"
+#include "list.h"
+#include <stddef.h>
+#include <stdint.h>
+
+/**
+ * A leaf of a trie.
+ */
+struct trie_leaf {
+	/** Linked list of leaves, in insertion order. */
+	struct trie_leaf *prev, *next;
+	/** 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 trie_leaf *head, *tail;
+	/** Node allocator. */
+	struct varena nodes;
+	/** Leaf allocator. */
+	struct varena 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);
+
+/**
+ * Remove all leaves from a trie.
+ */
+void trie_clear(struct trie *trie);
+
+/**
+ * Destroy a trie and its contents.
+ */
+void trie_destroy(struct trie *trie);
+
+/**
+ * Iterate over the leaves of a trie.
+ */
+#define for_trie(leaf, trie) \
+	for_list (struct trie_leaf, leaf, trie)
+
+#endif // BFS_TRIE_H