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#include "map.h"
#include "crash.h"
#include <stdlib.h>
#include <assert.h>
#define DEFAULT_CAPACITY 16
void map_init(
map_t* map,
hash_func_t hash_func,
eq_func_t eq_func,
double load_limit
) {
map_init_capacity(
map, hash_func, eq_func, load_limit, DEFAULT_CAPACITY);
}
void map_init_capacity(
map_t* map,
hash_func_t hash_func,
eq_func_t eq_func,
double load_limit,
size_t capacity
) {
map->hash_func = hash_func;
map->eq_func = eq_func;
map->load_limit = load_limit;
map->size = 0;
map->__num_buckets = capacity / load_limit + 1;
map->__buckets = calloc(map->__num_buckets, sizeof(struct __map_entry));
if (map->__buckets == NULL)
crash("Out of memory allocating %ld hash buckets\n");
}
void map_destroy(map_t* map) {
for (size_t i = 0; i < map->__num_buckets; i++) {
struct __map_entry* node = map->__buckets[i].next;
while (node != NULL) {
struct __map_entry* next = node->next;
free(node);
node = next;
}
}
free(map->__buckets);
}
/* impl detail: next is never null if the value is populated (put will alloc) */
static struct __map_entry* fetch_entry(const map_t* map, const void* key) {
struct __map_entry* entry =
&map->__buckets[map->hash_func(key) % map->__num_buckets];
while (entry->next != NULL && !map->eq_func(key, entry->key)) {
entry = entry->next;
}
return entry;
}
bool map_contains(const map_t* map, const void *key) {
return fetch_entry(map, key)->next != NULL;
}
void* map_get(const map_t* map, const void* key) {
return map_get_or_default(map, key, NULL);
}
void* map_get_or_default(const map_t* map, const void* key, void* default_val) {
struct __map_entry* entry = fetch_entry(map, key);
return entry->next == NULL ? default_val : entry->value;
}
static void insert_entry(map_t* map, struct __map_entry* entry) {
struct __map_entry* slot = fetch_entry(map, entry->key);
assert(slot->next == NULL);
slot->key = entry->key;
slot->value = entry->value;
slot->next = entry;
entry->next = NULL;
}
static void rehash(map_t* map) {
size_t old_num_buckets = map->__num_buckets;
struct __map_entry* old_buckets = map->__buckets;
map->__num_buckets <<= 1;
map->__buckets = calloc(map->__num_buckets, sizeof(struct __map_entry));
for (size_t i = 0; i < old_num_buckets; i++) {
struct __map_entry* old_entry = &old_buckets[i];
if (old_entry->next == NULL) continue;
struct __map_entry* cur = old_entry->next;
while (cur->next != NULL) {
struct __map_entry* next = cur->next;
insert_entry(map, cur);
cur = next;
}
struct __map_entry* new_entry = fetch_entry(map, old_entry->key);
new_entry->key = old_entry->key;
new_entry->value = old_entry->value;
new_entry->next = cur;
}
free(old_buckets);
}
static void insert_allocating(
map_t* map,
struct __map_entry* entry,
void* key,
void* val
) {
if ((double) ++map->size / map->__num_buckets > map->load_limit) {
rehash(map);
entry = fetch_entry(map, key);
}
struct __map_entry* next = calloc(1, sizeof(struct __map_entry));
if (next == NULL)
crash("Out of memory allocating hash entry\n");
entry->key = key;
entry->value = val;
entry->next = next;
}
void* map_compute_if_absent(map_t* map, void* key, void* default_val) {
struct __map_entry* entry = fetch_entry(map, key);
if (entry->next != NULL) return entry->value;
insert_allocating(map, entry, key, default_val);
return default_val;
}
void map_put(map_t* map, void* key, void* val) {
struct __map_entry* entry = fetch_entry(map, key);
if (entry->next != NULL) {
entry->value = val;
return;
}
insert_allocating(map, entry, key, val);
}
void* map_remove(map_t* map, const void* key) {
struct __map_entry* entry = fetch_entry(map, key);
if (entry->next == NULL) return NULL;
void* rv = entry->value;
struct __map_entry* steal = entry->next;
*entry = *steal;
free(steal);
return rv;
}
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