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#include <hashtbl.h>
#include <malloc.h>
#include <string.h>
#define DEFAULT_HT_INIT_SIZE 16
#define SLOT_OF_HASH(k, nslots) (((size_t)(k)*21179)%(size_t)(nslots))
typedef struct hashtbl_item {
void* key;
void* val;
struct hashtbl_item *next;
} hashtbl_item_t;
// When nitems > size * 3/4, size is multiplied by two
// When nitems < size * 1/4, size is divided by two
struct hashtbl {
key_eq_fun_t ef;
hash_fun_t hf;
kv_iter_fun_t releasef;
size_t size, nitems;
hashtbl_item_t **items;
};
hashtbl_t *create_hashtbl(key_eq_fun_t ef, hash_fun_t hf, kv_iter_fun_t on_release) {
hashtbl_t *ht = (hashtbl_t*)malloc(sizeof(hashtbl_t));
if (ht == 0) return 0;
ht->ef = ef;
ht->hf = hf;
ht->releasef = on_release;
ht->size = DEFAULT_HT_INIT_SIZE;
ht->nitems = 0;
ht->items = (hashtbl_item_t**)malloc(ht->size * sizeof(hashtbl_item_t*));
if (ht->items == 0) {
free(ht);
return 0;
}
for (size_t i = 0; i < ht->size; i++) ht->items[i] = 0;
return ht;
}
void delete_hashtbl(hashtbl_t *ht) {
// Free items
for (size_t i = 0; i < ht->size; i++) {
while (ht->items[i] != 0) {
hashtbl_item_t *x = ht->items[i];
ht->items[i] = x->next;
if (ht->releasef) ht->releasef(x->key, x->val);
free(x);
}
}
// Free table
free(ht->items);
free(ht);
}
static void hashtbl_check_size(hashtbl_t *ht) {
size_t nsize = 0;
if (4 * ht->nitems < ht->size) nsize = ht->size / 2;
if (4 * ht->nitems > 3 * ht->size) nsize = ht->size * 2;
if (nsize != 0) {
hashtbl_item_t **nitems = (hashtbl_item_t**)malloc(nsize * sizeof(hashtbl_item_t*));
if (nitems == 0) return; // if we can't realloc, too bad, we just lose space
for (size_t i = 0; i < nsize; i++) nitems[i] = 0;
// rehash
for (size_t i = 0; i < ht->size; i++) {
while (ht->items[i] != 0) {
hashtbl_item_t *x = ht->items[i];
ht->items[i] = x->next;
size_t slot = SLOT_OF_HASH(ht->hf(x->key), nsize);
x->next = nitems[slot];
nitems[slot] = x;
}
}
free(ht->items);
ht->size = nsize;
ht->items = nitems;
}
}
bool hashtbl_add(hashtbl_t *ht, void* key, void* v) {
size_t slot = SLOT_OF_HASH(ht->hf(key), ht->size);
hashtbl_item_t *i = (hashtbl_item_t*)malloc(sizeof(hashtbl_item_t));
if (i == 0) return false; // OOM
// make sure item is not already present
hashtbl_remove(ht, key);
i->key = key;
i->val = v;
i->next = ht->items[slot];
ht->items[slot] = i;
ht->nitems++;
hashtbl_check_size(ht);
return true;
}
void* hashtbl_find(hashtbl_t* ht, const void* key) {
size_t slot = SLOT_OF_HASH(ht->hf(key), ht->size);
for (hashtbl_item_t *i = ht->items[slot]; i != 0; i = i->next) {
if (ht->ef(i->key, key)) return i->val;
}
return 0;
}
void hashtbl_remove(hashtbl_t* ht, const void* key) {
size_t slot = SLOT_OF_HASH(ht->hf(key), ht->size);
if (ht->items[slot] == 0) return;
hashtbl_item_t *x = 0;
if (ht->ef(ht->items[slot]->key, key)) {
x = ht->items[slot];
ht->items[slot] = x->next;
} else {
for (hashtbl_item_t *i = ht->items[slot]; i->next != 0; i = i->next) {
if (ht->ef(i->next->key, key)) {
x = i->next;
i->next = x->next;
break;
}
}
}
if (x != 0) {
ht->nitems--;
if (ht->releasef) ht->releasef(x->key, x->val);
free(x);
}
hashtbl_check_size(ht);
}
size_t hashtbl_count(hashtbl_t* ht) {
return ht->nitems;
}
// ================================== //
// UTILITY FUNCTIONS (HASH, EQ, FREE) //
// ================================== //
hash_t id_hash_fun(const void* v) {
return (hash_t)v;
}
hash_t str_hash_fun(const void* v) {
hash_t h = 712;
for (char* s = (char*)v; *s != 0; s++) {
h = h * 101 + *s;
}
return h;
}
bool id_key_eq_fun(const void* a, const void* b) {
return a == b;
}
bool str_key_eq_fun(const void* a, const void* b) {
return strcmp((const char*)a, (const char*)b) == 0;
}
void free_key(void* key, void* val) {
free(key);
}
void free_val(void* key, void* val) {
free(val);
}
void free_key_val(void* key, void* val) {
free(key);
free(val);
}
/* vim: set ts=4 sw=4 tw=0 noet :*/
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