/*
* Copyright (C) 2006 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This is an implementation of generic chained hash table.
*/
#include <hash_table.h>
#include <list.h>
#include <unistd.h>
#include <malloc.h>
#include <assert.h>
#include <stdio.h>
#include <string.h>
/** Create chained hash table.
*
* @param h Hash table structure. Will be initialized by this call.
* @param m Number of slots in the hash table.
* @param max_keys Maximal number of keys needed to identify an item.
* @param op Hash table operations structure.
* @return true on success
*/
int hash_table_create(hash_table_t *h, hash_count_t m, hash_count_t max_keys, hash_table_operations_t *op)
{
hash_count_t i;
assert(op
&& op
->hash
&& op
->compare
);
h
->entry
= malloc(m
* sizeof(link_t
)); if (!h->entry) {
printf("cannot allocate memory for hash table\n"); return false;
}
memset((void *) h
->entry
, 0, m
* sizeof(link_t
));
for (i = 0; i < m; i++)
list_initialize(&h->entry[i]);
h->entries = m;
h->max_keys = max_keys;
h->op = op;
return true;
}
/** Insert item into hash table.
*
* @param h Hash table.
* @param hey Array of all keys necessary to compute hash index.
* @param item Item to be inserted into the hash table.
*/
void hash_table_insert(hash_table_t *h, unsigned long key[], link_t *item)
{
hash_index_t chain;
assert(h
&& h
->op
&& h
->op
->hash
&& h
->op
->compare
);
chain = h->op->hash(key);
list_append(item, &h->entry[chain]);
}
/** Search hash table for an item matching keys.
*
* @param h Hash table.
* @param key Array of all keys needed to compute hash index.
*
* @return Matching item on success, NULL if there is no such item.
*/
link_t *hash_table_find(hash_table_t *h, unsigned long key[])
{
link_t *cur;
hash_index_t chain;
assert(h
&& h
->op
&& h
->op
->hash
&& h
->op
->compare
);
chain = h->op->hash(key);
/*
* The hash table is not redundant.
* Check if the keys are not in place already.
*/
for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
if (h->op->compare(key, h->max_keys, cur)) {
/*
* The entry is there.
*/
return cur;
}
}
return NULL;
}
/** Remove all matching items from hash table.
*
* For each removed item, h->remove_callback() is called.
*
* @param h Hash table.
* @param key Array of keys that will be compared against items of the hash table.
* @param keys Number of keys in the 'key' array.
*/
void hash_table_remove(hash_table_t *h, unsigned long key[], hash_count_t keys)
{
hash_index_t chain;
link_t *cur;
assert(h
&& h
->op
&& h
->op
->hash
&& h
->op
->compare
&& h
->op
->remove_callback
);
if (keys == h->max_keys) {
/*
* All keys are known, hash_table_find() can be used to find the entry.
*/
cur = hash_table_find(h, key);
if (cur) {
list_remove(cur);
h->op->remove_callback(cur);
}
return;
}
/*
* Fewer keys were passed.
* Any partially matching entries are to be removed.
*/
for (chain = 0; chain < h->entries; chain++) {
for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
if (h->op->compare(key, keys, cur)) {
link_t *hlp;
hlp = cur;
cur = cur->prev;
list_remove(hlp);
h->op->remove_callback(hlp);
continue;
}
}
}
}