- hashtable
hashtable object to operate on
- htiter
object to iterate through all items in a hashtable
- hash_t
return value of hash function, castable to size_t (atm: unsigned long)
initializing a hashtable:
int ht_init(hashtable **ht,
hash_t (*hashfunc)(const void*, const void*)
int (*cmpfunc)(const void*, const void*, const void*);
int ht_init_f(hashtable **ht,
hash_t (*hashfunc)(const void*, const void*)
int (*cmpfunc)(const void*, const void*, const void*),
void (*free_key)(void*),
void (*free_data)(void*);free a hashtable and all keys/data:
void ht_free(hashtable *ht);
void ht_free_f(hashtable *ht,
void (*free_key)(void*), void (*free_data)(void*));determine if hashtable is empty:
int ht_empty(hashtable *ht);insert (not overwrite!) an item:
int ht_insert(hashtable *ht, void *key, void *data);
int ht_insert_a(hashtable *ht, void *key, void *data,
const void *hash_arg, const void *cmp_arg);overwrite existing / insert new item:
int ht_set(hashtable *ht, void *key, void *data);
int ht_set_a(hashtable *ht, void *key, void *data,
const void *hash_arg, const void *cmp_arg);
int ht_set_f(hashtable *ht, void *key, void *data,
void (*free_key)(void*), void (*free_data)(void*));
int ht_set_fa(hashtable *ht, void *key, void *data,
void (*free_key)(void*), void (*free_data)(void*),
const void *hash_arg, const void *cmp_arg);retrieve stored data:
void *ht_get(hashtable *ht, const void *key);
void *ht_get_a(hashtable *ht, const void *key,
const void *hash_arg, const void *cmp_arg);remove and retrieve data:
void *ht_remove(hashtable *ht, const void *key);
void *ht_remove_a(hashtable *ht, const void *key,
const void *hash_arg, const void *cmp_arg);
void *ht_remove_f(hashtable *ht, const void *key,
void (*free_key)(void*));
void *ht_remove_fa(hashtable *ht, const void *key,
void (*free_key)(void*),
const void *hash_arg, const void *cmp_arg);pop (retrieve & remove) the first item (first item in first non-empty bucket):
void ht_pop(hashtable *ht, void **key, void **data);create iteration object (can be free'd with free()):
htiter *ht_iter(hashtable *ht);retrieve next key and data (returns 0 if nothing retrieved):
int htiter_next(htiter *it, void **key, void **data);Define a hash function that takes two
const void*arguments and returns an integer value of typehash_t:- The first argument will be the key of a hashtable entry (-> the value to be hashed)
- The second argument is passed when using one of the
[...]_a()or[...]_fa()functions, elseNULL
Define a compare function that takes three
const void*arguments and returns anintwith value 0 if the first two arguments are semantically equal (like i.e.strcmp())- The first two argument will be two keys to compare
- The third argument is, again, used with
[...]_a()or[...]_fa()
- Define functions that take one void* argument which will free key and data of your hashtable entries.
Declare and initialize a hashtable* object, using one of the following functions:
ht_init()which takes the following arguments:- A pointer to your hashtable* object
- Your hash function
- Your compare function
ht_init_f()which takes the same arguemts asht_init()plus- Your function to free keys
- Your function to free data
If you use
ht_init()you can still free keys and data by using the[...]_f()or[...]_fa()functions which also take freeing functions as arguments
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "hashtable.h"
hash_t my_hash(const void *key, const void *arg);
int my_cmp(const void *key1, const void *key2, const void *arg);
hash_t my_hash(const void *key, const void *arg) {
hash_t hash = 5381;
const char *str = (const char*)key;
size_t n;
int c;
if (!arg) {
while ((c = *str++))
hash = ((hash << 5) + hash) + c;
}
else {
n = *(size_t*)arg;
while ((c = *str++) && n-- > 0)
hash = ((hash << 5) + hash) + c;
}
return hash;
}
int my_cmp(const void *key1, const void *key2, const void *arg) {
size_t n;
if (!arg) {
return strcmp((const char*)key1, (const char*)key2);
}
else {
n = *(size_t*)arg;
return strncmp((const char*)key1, (const char*)key2, n);
}
}
int main(int argc, char **argv) {
hashtable *ht;
ht_init_f(&ht, my_hash, my_cmp, free, free);
[ ... ]
return EXIT_SUCCESS;
}