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author | Daniel Silverstone <dsilvers@digital-scurf.org> | 2020-02-23 15:12:37 +0000 |
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committer | Daniel Silverstone <dsilvers@digital-scurf.org> | 2020-02-23 15:13:47 +0000 |
commit | a653e1e86eb5af1621de97603c33222315d2d2c3 (patch) | |
tree | 3215aff047de10476ba3fceaf821c669bd3e01eb /utils/hashmap.h | |
parent | f3b7a0c44cbf006679faabf9e4d971b2e62cc37a (diff) | |
download | netsurf-a653e1e86eb5af1621de97603c33222315d2d2c3.tar.gz |
utils: Add a generic hashmap and tests for it
In order to be able to use a generic hashmap in things such
as the fs_backing_store we want one to exist. Here it is,
along with some moderately comprehensive tests.
Current limits:
1. All keys and values are owned by the hashmap
2. The hashmap, while capable of different bucket counts
only has a single fixed count for now
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>
Diffstat (limited to 'utils/hashmap.h')
-rw-r--r-- | utils/hashmap.h | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/utils/hashmap.h b/utils/hashmap.h new file mode 100644 index 000000000..4e1237ae9 --- /dev/null +++ b/utils/hashmap.h @@ -0,0 +1,137 @@ +/* + * 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; + +/** + * Parameters for hashmaps + */ +typedef struct { + /** + * A function which when called will clone a key and give + * ownership of the returned object to the hashmap + */ + void * (*key_clone)(void *key); + + /** + * A function which when given a key will return its hash. + */ + uint32_t (*key_hash)(void *key); + + /** + * 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) + */ + bool (*key_eq)(void *key1, void *key2); + + /** + * A function which when called will destroy a key object + */ + void (*key_destroy)(void *key); + + /** + * A function which when called will allocate a value object + */ + void * (*value_alloc)(void *key); + + /** + * A function which when called will destroy a value object + */ + void (*value_destroy)(void *value); +} 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); + + +#endif |