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/*
* hash.h
*
* Copyright (C) 2004-2011 Simon Wunderlich <sw@simonwunderlich.de>
* Copyright (C) 2004-2011 Marek Lindner <mareklindner@neomailbox.ch>
*
* This file is part of the s3d API, the API of s3d (the 3d network display server).
* See http://s3d.berlios.de/ for more updates.
*
* The s3d API is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* The s3d API is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the s3d API; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h> /* NULL */
#include <stdlib.h> /* malloc(), free() */
#include "hash.h"
/* clears the hash */
void _s3d_hash_init(struct hashtable_t *hash)
{
int i;
hash->elements = 0;
for (i = 0 ; i < hash->size ; i++) {
hash->table[i] = NULL;
}
}
/* remove the hash structure. if hashdata_free_cb != NULL,
* this function will be called to remove the elements inside of the hash.
* if you don't remove the elements, memory might be leaked. */
void _s3d_hash_delete(struct hashtable_t *hash, hashdata_free_cb free_cb)
{
struct element_t *bucket, *last_bucket;
int i;
for (i = 0; i < hash->size; i++) {
bucket = hash->table[i];
while (bucket != NULL) {
if (free_cb != NULL)
free_cb(bucket->data);
last_bucket = bucket;
bucket = bucket->next;
free(last_bucket);
}
}
_s3d_hash_destroy(hash);
}
/* free only the hashtable and the hash itself. */
void _s3d_hash_destroy(struct hashtable_t *hash)
{
free(hash->table);
free(hash);
}
/* iterate though the hash. first element is selected with iter_in NULL.
* use the returned iterator to access the elements until hash_it_t returns NULL. */
struct hash_it_t *_s3d_hash_iterate(struct hashtable_t *hash, struct hash_it_t *iter_in) {
struct hash_it_t *iter;
if (iter_in == NULL) {
iter = (struct hash_it_t*)malloc(sizeof(struct hash_it_t));
iter->index = -1;
iter->bucket = NULL;
iter->prev_bucket = NULL;
} else
iter = iter_in;
/* sanity checks first (if our bucket got deleted in the last iteration): */
if (iter->bucket != NULL) {
if (iter->first_bucket != NULL) {
/* we're on the first element and it got removed after the last iteration. */
if ((*iter->first_bucket) != iter->bucket) {
/* there are still other elements in the list */
if ((*iter->first_bucket) != NULL) {
iter->prev_bucket = NULL;
iter->bucket = (*iter->first_bucket);
iter->first_bucket = &hash->table[ iter->index ];
return iter;
} else {
iter->bucket = NULL;
}
}
} else if (iter->prev_bucket != NULL) {
/* we're not on the first element, and the bucket got removed after the last iteration.
* the last bucket's next pointer is not pointing to our actual bucket anymore.
* select the next. */
if (iter->prev_bucket->next != iter->bucket)
iter->bucket = iter->prev_bucket;
}
}
/* now as we are sane, select the next one if there is some */
if (iter->bucket != NULL) {
if (iter->bucket->next != NULL) {
iter->prev_bucket = iter->bucket;
iter->bucket = iter->bucket->next;
iter->first_bucket = NULL;
return iter;
}
}
/* if not returned yet, we've reached the last one on the index and have to search forward */
iter->index++;
while (iter->index < hash->size) { /* go through the entries of the hash table */
if ((hash->table[ iter->index ]) != NULL) {
iter->prev_bucket = NULL;
iter->bucket = hash->table[ iter->index ];
iter->first_bucket = &hash->table[ iter->index ];
return iter; /* if this table entry is not null, return it */
} else
iter->index++; /* else, go to the next */
}
/* nothing to iterate over anymore */
free(iter);
return NULL;
}
/* allocates and clears the hash */
struct hashtable_t *_s3d_hash_new(int size, hashdata_compare_cb compare, hashdata_choose_cb choose) {
struct hashtable_t *hash;
hash = (struct hashtable_t*)malloc(sizeof(struct hashtable_t));
if (hash == NULL) /* could not allocate the hash control structure */
return NULL;
hash->size = size;
hash->table = (struct element_t **)malloc(sizeof(struct element_t *) * size);
if (hash->table == NULL) { /* could not allocate the table */
free(hash);
return NULL;
}
_s3d_hash_init(hash);
hash->compare = compare;
hash->choose = choose;
return hash;
}
/* adds data to the hashtable. returns 0 on success, -1 on error */
int _s3d_hash_add(struct hashtable_t *hash, void *data)
{
int index;
struct element_t *bucket, *prev_bucket = NULL;
index = hash->choose(data, hash->size);
bucket = hash->table[index];
while (bucket != NULL) {
if (0 == hash->compare(bucket->data, data))
return -1;
prev_bucket = bucket;
bucket = bucket->next;
}
/* found the tail of the list, add new element */
if (NULL == (bucket = (struct element_t*)malloc(sizeof(struct element_t))))
return -1; /* malloc failed */
bucket->data = data; /* init the new bucket */
bucket->next = NULL;
/* and link it */
if (prev_bucket == NULL) {
hash->table[index] = bucket;
} else {
prev_bucket->next = bucket;
}
hash->elements++;
return 0;
}
/* finds data, based on the key in keydata. returns the found data on success, or NULL on error */
void *_s3d_hash_find(struct hashtable_t *hash, void *keydata)
{
int index;
struct element_t *bucket;
index = hash->choose(keydata , hash->size);
bucket = hash->table[index];
while (bucket != NULL) {
if (0 == hash->compare(bucket->data, keydata))
return bucket->data;
bucket = bucket->next;
}
return NULL;
}
/* remove bucket (this might be used in hash_iterate() if you already found the bucket
* you want to delete and don't need the overhead to find it again with hash_remove().
* But usually, you don't want to use this function, as it fiddles with hash-internals. */
void *_s3d_hash_remove_bucket(struct hashtable_t *hash, struct hash_it_t *hash_it_t)
{
void *data_save;
data_save = hash_it_t->bucket->data; /* save the pointer to the data */
if (hash_it_t->prev_bucket != NULL) {
hash_it_t->prev_bucket->next = hash_it_t->bucket->next;
} else if (hash_it_t->first_bucket != NULL) {
(*hash_it_t->first_bucket) = hash_it_t->bucket->next;
}
free(hash_it_t->bucket);
hash->elements--;
return data_save;
}
/* removes data from hash, if found. returns pointer do data on success,
* so you can remove the used structure yourself, or NULL on error .
* data could be the structure you use with just the key filled,
* we just need the key for comparing. */
void *_s3d_hash_remove(struct hashtable_t *hash, void *data)
{
struct hash_it_t hash_it_t;
hash_it_t.index = hash->choose(data, hash->size);
hash_it_t.bucket = hash->table[hash_it_t.index];
hash_it_t.prev_bucket = NULL;
while (hash_it_t.bucket != NULL) {
if (0 == hash->compare(hash_it_t.bucket->data, data)) {
hash_it_t.first_bucket = (hash_it_t.bucket == hash->table[hash_it_t.index] ? &hash->table[ hash_it_t.index ] : NULL);
return _s3d_hash_remove_bucket(hash, &hash_it_t);
}
hash_it_t.prev_bucket = hash_it_t.bucket;
hash_it_t.bucket = hash_it_t.bucket->next;
}
return NULL;
}
/* resize the hash, returns the pointer to the new hash or NULL on error. removes the old hash on success. */
struct hashtable_t *_s3d_hash_resize(struct hashtable_t *hash, int size) {
struct hashtable_t *new_hash;
struct element_t *bucket;
int i;
/* initialize a new hash with the new size */
if (NULL == (new_hash = _s3d_hash_new(size, hash->compare, hash->choose)))
return NULL;
/* copy the elements */
for (i = 0; i < hash->size; i++) {
bucket = hash->table[i];
while (bucket != NULL) {
_s3d_hash_add(new_hash, bucket->data);
bucket = bucket->next;
}
}
_s3d_hash_delete(hash, NULL); /* remove hash and eventual overflow buckets but not the content itself. */
return new_hash;
}
/* print the hash table for debugging */
void _s3d_hash_debug(struct hashtable_t *hash)
{
int i;
struct element_t *bucket;
for (i = 0; i < hash->size; i++) {
printf("[%d] ", i);
bucket = hash->table[i];
while (bucket != NULL) {
printf("-> [%10p] ", (void *)bucket);
bucket = bucket->next;
}
printf("\n");
}
printf("\n");
}
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