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+/*
+ * Copyright 2020 Daniel Silverstone <dsilvers@netsurf-browser.org>
+ *
+ * This file is part of NetSurf, http://www.netsurf-browser.org/
+ *
+ * NetSurf is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * NetSurf is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NETSURF_HASHMAP_H
+#define NETSURF_HASHMAP_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/**
+ * Generic hashmap.
+ *
+ * Hashmaps take ownership of the keys inserted into them by means of a
+ * clone function in their parameters.  They also manage the value memory
+ * directly.
+ */
+typedef struct hashmap_s hashmap_t;
+
+/**
+ * Key cloning function type
+ */
+typedef void* (*hashmap_key_clone_t)(void *);
+
+/**
+ * Key destructor function type
+ */
+typedef void (*hashmap_key_destroy_t)(void *);
+
+/**
+ * Key hashing function type
+ */
+typedef uint32_t (*hashmap_key_hash_t)(void *);
+
+/**
+ * Key comparison function type
+ */
+typedef bool (*hashmap_key_eq_t)(void *, void*);
+
+/**
+ * Value allocation function type
+ */
+typedef void* (*hashmap_value_alloc_t)(void *);
+
+/**
+ * Value destructor function type
+ */
+typedef void (*hashmap_value_destroy_t)(void *);
+
+/**
+ * Hashmap iteration callback function type.
+ *
+ * First parameter is the key, second is the value.
+ * The final parameter is the context pointer for the iteration.
+ *
+ * Return true to stop iterating early
+ */
+typedef bool (*hashmap_iteration_cb_t)(void *, void *, void *);
+
+/**
+ * Parameters for hashmaps
+ */
+typedef struct {
+	/**
+	 * A function which when called will clone a key and give
+	 * ownership of the returned object to the hashmap
+	 */
+	hashmap_key_clone_t key_clone;
+
+	/**
+	 * A function which when given a key will return its hash.
+	 */
+	hashmap_key_hash_t key_hash;
+	
+	/**
+	 * A function to compare two keys and return if they are equal.
+	 * Note: identity is not necessary, nor strict equality, so long
+	 * as the function is a full equality model.
+	 * (i.e. key1 == key2 => key2 == key1)
+	 */
+	hashmap_key_eq_t key_eq;
+	 
+	/**
+	 * A function which when called will destroy a key object
+	 */
+	hashmap_key_destroy_t key_destroy;
+
+	/**
+	 * A function which when called will allocate a value object
+	 */
+	hashmap_value_alloc_t value_alloc;
+
+	/**
+	 * A function which when called will destroy a value object
+	 */
+	hashmap_value_destroy_t value_destroy;
+} hashmap_parameters_t;
+
+
+/**
+ * Create a hashmap
+ *
+ * The provided hashmap parameter table will be used for map operations
+ * which need to allocate/free etc.
+ *
+ * \param params The hashmap parameters for this map
+ */
+hashmap_t* hashmap_create(hashmap_parameters_t *params);
+
+/**
+ * Destroy a hashmap
+ *
+ * After this, all keys and values will have been destroyed and all memory
+ * associated with this hashmap will be invalidated.
+ *
+ * \param hashmap The hashmap to destroy
+ */
+void hashmap_destroy(hashmap_t *hashmap);
+
+/**
+ * Look up a key in a hashmap
+ *
+ * If the key has an associated value in the hashmap then the pointer to it
+ * is returned, otherwise NULL.
+ *
+ * \param hashmap The hashmap to look up the key inside
+ * \param key The key to look up in the hashmap
+ * \return A pointer to the value if found, NULL otherwise
+ */
+void* hashmap_lookup(hashmap_t *hashmap, void *key);
+
+/**
+ * Create an entry in a hashmap
+ *
+ * This creates a blank value using the parameters and then associates it with
+ * a clone of the given key, inserting it into the hashmap.  If a value was
+ * present for the given key already, then it is destroyed first.
+ *
+ * NOTE: If allocation of the new value object fails, then any existing entry
+ * will be left alone, but NULL will be returned.
+ *
+ * \param hashmap The hashmap to insert into
+ * \param key The key to insert an entry for
+ * \return The value pointer for that key, or NULL if allocation failed.
+ */
+void *hashmap_insert(hashmap_t *hashmap, void *key);
+
+/**
+ * Remove an entry from the hashmap
+ *
+ * This will remove the entry for the given key from the hashmap
+ * If there is no such entry, this will safely do nothing.
+ * The value associated with the entry will be destroyed and so should not
+ * be used beyond calling this function.
+ *
+ * \param hashmap The hashmap to remove the entry from
+ * \param key The key to remove the entry for
+ * \return true if an entry was removed, false otherwise
+ */
+bool hashmap_remove(hashmap_t *hashmap, void *key);
+
+/**
+ * Iterate the hashmap
+ *
+ * For each key/value pair in the hashmap, call the callback passing in
+ * the key and value.  During iteration you MUST NOT mutate the hashmap.
+ *
+ * \param hashmap The hashmap to iterate
+ * \param cb The callback for each key,value pair
+ * \param ctx The callback context
+ * \return Whether or not we stopped iteration early
+ */
+bool hashmap_iterate(hashmap_t *hashmap, hashmap_iteration_cb_t cb, void *ctx);
+
+/**
+ * Get the number of entries in this map
+ *
+ * \param hashmap The hashmap to retrieve the entry count from
+ * \return The number of entries in the hashmap
+ */
+size_t hashmap_count(hashmap_t *hashmap);
+
+#endif