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/* hashtbl.c
*
* Hash Table
*
*/
#include "hashtbl.h"
#include "hashfuncs.h"
char *strdup(const char *s)
{
char *b;
if (!(b = malloc(strlen(s) + 1)))
return NULL;
strcpy(b, s);
return b;
}
HASHTBL *hashtbl_create(size_t size, unsigned int (*hashfunc)(const char *))
{
HASHTBL *hashtbl;
if (!(hashtbl = malloc(sizeof(HASHTBL))))
return NULL;
/* pointer array of nodes */
if (!(hashtbl->nodes = calloc(size, sizeof(struct hashnode_s*))))
{
free(hashtbl);
return NULL;
}
hashtbl->size = size;
if (hashfunc)
hashtbl->hashfunc = hashfunc;
else
hashtbl->hashfunc = aphash;
return hashtbl;
}
void hashtbl_destroy(HASHTBL *hashtbl)
{
size_t n;
struct hashnode_s *node, *oldnode;
for (n = 0; n<hashtbl->size; ++n) {
node = hashtbl->nodes[n];
while (node) {
free(node->key);
oldnode = node;
node = node->next;
free(oldnode);
}
}
free(hashtbl->nodes);
free(hashtbl);
}
int hashtbl_insert(HASHTBL *hashtbl, const char *key, void *data)
{
struct hashnode_s *head;
size_t hash = hashtbl->hashfunc(key) % hashtbl->size;
/* fprintf(stderr, "hashtbl_insert() key = %s, hash = %d, data = %s\n", key, hash, (char*)data); */
head = hashtbl->nodes[hash];
while (head)
{
if (!strcmp(head->key, key))
{
/* update the data in currently existing node */
head->data = data;
return 0;
}
head = head->next;
}
/* if we get here, it means that this is the first node at particular index
* or we are appending new node to the end of the linked list */
if (!(head = malloc(sizeof(struct hashnode_s))))
return -1;
if (!(head->key = strdup(key)))
{
free(head);
return -1;
}
head->data = data;
head->next = hashtbl->nodes[hash];
/* update head ptr */
hashtbl->nodes[hash] = head;
return 0;
}
int hashtbl_remove(HASHTBL *hashtbl, const char *key)
{
struct hashnode_s *node, *prevnode = NULL;
size_t hash = hashtbl->hashfunc(key) % hashtbl->size;
node = hashtbl->nodes[hash];
while (node)
{
if (!strcmp(node->key, key))
{
free(node->key);
if (prevnode)
prevnode->next = node->next;
else
hashtbl->nodes[hash] = node->next;
free(node);
return 0;
}
prevnode = node;
node = node->next;
}
return -1;
}
void *hashtbl_get(HASHTBL *hashtbl, const char *key)
{
struct hashnode_s *head;
size_t hash = hashtbl->hashfunc(key) % hashtbl->size;
/* fprintf(stderr, "hashtbl_get() key = %s, hash = %d\n", key, hash);*/
head = hashtbl->nodes[hash];
while (head)
{
/* return data only when keys match */
if (!strcmp(head->key, key))
return head->data;
head = head->next;
}
return NULL;
}
int hashtbl_resize(HASHTBL *hashtbl, size_t size)
{
HASHTBL newtbl;
size_t n;
struct hashnode_s *node,*next;
newtbl.size = size;
newtbl.hashfunc = hashtbl->hashfunc;
if (!(newtbl.nodes = calloc(size, sizeof(struct hashnode_s*)))) return -1;
for (n = 0; n<hashtbl->size; ++n) {
for (node = hashtbl->nodes[n]; node; node = next) {
next = node->next;
hashtbl_insert(&newtbl, node->key, node->data);
hashtbl_remove(hashtbl, node->key);
}
}
free(hashtbl->nodes);
hashtbl->size = newtbl.size;
hashtbl->nodes = newtbl.nodes;
return 0;
}
int main(int argc, char **argv)
{
char *key = "abcdefghijklmnopqrstuvwxyz1234567890";
(void) printf("Hash Functions\n");
(void) printf("Key: %s\n\n", key);
(void) printf("ASCII default hash function value: %u\n", defaulthash(key));
(void) printf("RS hash function value: %u\n", rshash(key));
(void) printf("JS hash function value: %u\n", jshash(key));
(void) printf("PJW hash function value: %u\n", pjwhash(key));
(void) printf("ELF hash function value: %u\n", elfhash(key));
(void) printf("BKDR hash function value: %u\n", bkdrhash(key));
(void) printf("SDBM hash function value: %u\n", sdbmhash(key));
(void) printf("DJB hash function value: %u\n", djbhash(key));
(void) printf("DEK hash function value: %u\n", dekhash(key));
(void) printf("BP hash function value: %u\n", bphash(key));
(void) printf("FNV hash function value: %u\n", fnvhash(key));
(void) printf("AP hash function value: %u\n", aphash(key));
(void) puts("");
HASHTBL *hashtbl;
char *italy, *spain;
hashtbl = hashtbl_create(16, NULL);
if (hashtbl == NULL)
{
fprintf(stderr, "error: hashtbl_create() failed\n");
exit(-1);
}
hashtbl_insert(hashtbl, "France", "Paris");
hashtbl_insert(hashtbl, "England", "London");
hashtbl_insert(hashtbl, "Sweden", "Stockholm");
hashtbl_insert(hashtbl, "Germany", "Berlin");
hashtbl_insert(hashtbl, "Norway", "Oslo");
hashtbl_insert(hashtbl, "Italy", "Rome");
hashtbl_insert(hashtbl, "Spain", "Madrid");
hashtbl_insert(hashtbl, "Estonia", "Tallinn");
hashtbl_insert(hashtbl, "Netherlands", "Amsterdam");
hashtbl_insert(hashtbl, "Ireland", "Dublin");
italy = hashtbl_get(hashtbl, "Italy");
(void) printf("Italy: %s\n", italy ? italy : "");
spain = hashtbl_get(hashtbl, "Spain");
(void) printf("Spain: %s\n", spain ? spain : "");
hashtbl_destroy(hashtbl);
return 0;
}
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