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#include "hashmap.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#define INITIAL_SIZE (16)
#define LOAD_FACTOR_THRESHOLD (0.75)
typedef struct Pair {
char *key;
void *value;
struct Pair *next;
} Pair;
typedef struct HashMap {
Pair **table;
size_t size;
size_t count;
} HashMap;
typedef struct HashMapKeysIter {
HashMap *map;
size_t bucket_index;
Pair *current;
} HashMapKeysIter;
static unsigned int hash(const char *key, size_t size) {
unsigned int hash_value = 0;
while (*key) hash_value = (hash_value * 31) + *key++;
return hash_value % size;
}
static void resize(HashMap *map) {
size_t new_size = map->size * 2;
Pair **new_table = (Pair**)calloc(new_size, sizeof(Pair*));
assert(new_table);
for (size_t i = 0; i < map->size; ++i) {
Pair *pair = map->table[i];
while (pair) {
unsigned int index = hash(pair->key, new_size);
Pair *next = pair->next;
pair->next = new_table[index];
new_table[index] = pair;
pair = next;
}
}
free(map->table);
map->table = new_table;
map->size = new_size;
}
HashMap *hashmap_create(void) {
HashMap *map = (HashMap*)malloc(sizeof(HashMap));
assert(map);
map->size = INITIAL_SIZE;
map->count = 0;
map->table = (Pair**)calloc(map->size, sizeof(Pair*));
assert(map->table);
return map;
}
void hashmap_insert(HashMap *map, const char *key, void *value) {
void **old_value = hashmap_get(map, key);
if (old_value) {
*old_value = value;
return;
}
if ((float)map->count / map->size > LOAD_FACTOR_THRESHOLD) resize(map);
unsigned int index = hash(key, map->size);
Pair *new_pair = (Pair*)malloc(sizeof(Pair));
assert(new_pair);
new_pair->key = strdup(key);
assert(new_pair->key);
new_pair->value = value;
new_pair->next = map->table[index];
map->table[index] = new_pair;
map->count++;
}
void **hashmap_get(HashMap *map, const char *key) {
unsigned int index = hash(key, map->size);
Pair *pair = map->table[index];
while (pair) {
if (strcmp(pair->key, key) == 0) return &pair->value;
pair = pair->next;
}
return NULL;
}
int hashmap_delete(HashMap *map, const char *key) {
unsigned int index = hash(key, map->size);
Pair *pair = map->table[index];
Pair *prev = NULL;
while (pair) {
if (strcmp(pair->key, key) == 0) {
if (prev) prev->next = pair->next;
else map->table[index] = pair->next;
free(pair->key);
free(pair);
map->count--;
return 0;
}
prev = pair;
pair = pair->next;
}
return -1;
}
void hashmap_free(HashMap *map) {
for (size_t i = 0; i < map->size; ++i) {
Pair *pair = map->table[i];
while (pair) {
Pair *temp = pair;
pair = pair->next;
free(temp->key);
free(temp);
}
}
free(map->table);
free(map);
}
HashMapKeysIter *hashmap_keys_iter_create(HashMap *map) {
HashMapKeysIter *iter = (HashMapKeysIter*)malloc(sizeof(HashMapKeysIter));
assert(iter);
iter->map = map;
iter->bucket_index = 0;
iter->current = NULL;
while (iter->bucket_index < map->size && map->table[iter->bucket_index] == NULL) {
iter->bucket_index++;
}
if (iter->bucket_index < map->size) {
iter->current = map->table[iter->bucket_index];
}
return iter;
}
const char *hashmap_keys_iter_next(HashMapKeysIter *iter) {
if (!iter->current) return NULL;
const char *key = iter->current->key;
if (iter->current->next) {
iter->current = iter->current->next;
} else {
iter->bucket_index++;
while (iter->bucket_index < iter->map->size && iter->map->table[iter->bucket_index] == NULL) {
iter->bucket_index++;
}
iter->current = (iter->bucket_index < iter->map->size) ? iter->map->table[iter->bucket_index] : NULL;
}
return key;
}
void hashmap_keys_iter_free(HashMapKeysIter *iter) {
free(iter);
}
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