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-rw-r--r--utils/hashmap.c215
-rw-r--r--utils/hashmap.h137
2 files changed, 352 insertions, 0 deletions
diff --git a/utils/hashmap.c b/utils/hashmap.c
new file mode 100644
index 000000000..7ed19946b
--- /dev/null
+++ b/utils/hashmap.c
@@ -0,0 +1,215 @@
+/*
+ * 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/>.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "utils/hashmap.h"
+
+/**
+ * The default number of buckets in the hashmaps we create.
+ */
+#define DEFAULT_HASHMAP_BUCKETS (4091)
+
+/**
+ * Hashmaps have chains of entries in buckets.
+ */
+typedef struct hashmap_entry_s {
+ struct hashmap_entry_s **prevptr;
+ struct hashmap_entry_s *next;
+ void *key;
+ void *value;
+ uint32_t key_hash;
+} hashmap_entry_t;
+
+/**
+ * The content of a hashmap
+ */
+struct hashmap_s {
+ /**
+ * The parameters to be used for this hashmap
+ */
+ hashmap_parameters_t *params;
+
+ /**
+ * The buckets for the hash chains
+ */
+ hashmap_entry_t **buckets;
+
+ /**
+ * The number of buckets in this map
+ */
+ uint32_t bucket_count;
+};
+
+/* Exported function, documented in hashmap.h */
+hashmap_t *
+hashmap_create(hashmap_parameters_t *params)
+{
+ hashmap_t *ret = malloc(sizeof(hashmap_t));
+
+ ret->params = params;
+ ret->bucket_count = DEFAULT_HASHMAP_BUCKETS;
+ ret->buckets = malloc(ret->bucket_count * sizeof(hashmap_entry_t *));
+ memset(ret->buckets, 0, ret->bucket_count * sizeof(hashmap_entry_t *));
+
+ if (ret->buckets == NULL) {
+ free(ret);
+ return NULL;
+ }
+
+ return ret;
+}
+
+/* Exported function, documented in hashmap.h */
+void
+hashmap_destroy(hashmap_t *hashmap)
+{
+ uint32_t bucket;
+ hashmap_entry_t *entry;
+
+ for (bucket = 0; bucket < hashmap->bucket_count; bucket++) {
+ for (entry = hashmap->buckets[bucket];
+ entry != NULL;
+ entry = entry->next) {
+ hashmap->params->value_destroy(entry->value);
+ hashmap->params->key_destroy(entry->key);
+ free(entry);
+ }
+ }
+
+ free(hashmap->buckets);
+ free(hashmap);
+}
+
+/* Exported function, documented in hashmap.h */
+void *
+hashmap_lookup(hashmap_t *hashmap, void *key)
+{
+ uint32_t hash = hashmap->params->key_hash(key);
+ hashmap_entry_t *entry = hashmap->buckets[hash % hashmap->bucket_count];
+
+ for(;entry != NULL; entry = entry->next) {
+ if (entry->key_hash == hash) {
+ if (hashmap->params->key_eq(key, entry->key)) {
+ return entry->value;
+ }
+ }
+ }
+
+ return NULL;
+}
+
+/* Exported function, documented in hashmap.h */
+void *
+hashmap_insert(hashmap_t *hashmap, void *key)
+{
+ uint32_t hash = hashmap->params->key_hash(key);
+ uint32_t bucket = hash % hashmap->bucket_count;
+ hashmap_entry_t *entry = hashmap->buckets[bucket];
+ void *new_key, *new_value;
+
+ for(;entry != NULL; entry = entry->next) {
+ if (entry->key_hash == hash) {
+ if (hashmap->params->key_eq(key, entry->key)) {
+ /* This key is already here */
+ new_key = hashmap->params->key_clone(key);
+ if (new_key == NULL) {
+ /* Allocation failed */
+ return NULL;
+ }
+ new_value = hashmap->params->value_alloc(entry->key);
+ if (new_value == NULL) {
+ /* Allocation failed */
+ hashmap->params->key_destroy(new_key);
+ return NULL;
+ }
+ hashmap->params->value_destroy(entry->value);
+ hashmap->params->key_destroy(entry->key);
+ entry->value = new_value;
+ entry->key = new_key;
+ return entry->value;
+ }
+ }
+ }
+
+ /* The key was not found in the map, so allocate a new entry */
+ entry = malloc(sizeof(*entry));
+
+ if (entry == NULL) {
+ return NULL;
+ }
+
+ memset(entry, 0, sizeof(*entry));
+
+ entry->key = hashmap->params->key_clone(key);
+ if (entry->key == NULL) {
+ goto err;
+ }
+ entry->key_hash = hash;
+
+ entry->value = hashmap->params->value_alloc(entry->key);
+ if (entry->value == NULL) {
+ goto err;
+ }
+
+ entry->prevptr = &(hashmap->buckets[bucket]);
+ entry->next = hashmap->buckets[bucket];
+ if (entry->next != NULL) {
+ entry->next->prevptr = &entry->next;
+ }
+
+ hashmap->buckets[bucket] = entry;
+
+ return entry->value;
+
+err:
+ if (entry->value != NULL)
+ hashmap->params->value_destroy(entry->value);
+ if (entry->key != NULL)
+ hashmap->params->key_destroy(entry->key);
+ free(entry);
+
+ return NULL;
+}
+
+/* Exported function, documented in hashmap.h */
+bool
+hashmap_remove(hashmap_t *hashmap, void *key)
+{
+ uint32_t hash = hashmap->params->key_hash(key);
+
+ hashmap_entry_t *entry = hashmap->buckets[hash % hashmap->bucket_count];
+
+ for(;entry != NULL; entry = entry->next) {
+ if (entry->key_hash == hash) {
+ if (hashmap->params->key_eq(key, entry->key)) {
+ hashmap->params->value_destroy(entry->value);
+ hashmap->params->key_destroy(entry->key);
+ if (entry->next != NULL) {
+ entry->next->prevptr = entry->prevptr;
+ }
+ *entry->prevptr = entry->next;
+ free(entry);
+ return true;
+ }
+ }
+ }
+
+ return false;
+}
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