hashtable_utility.c

simple and efficient hashtable

/* Copyright (C) 2002 Christopher Clark <[e-mail]> */

#include "hashtable.h"
#include "hashtable_private.h"
#include "hashtable_utility.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/*****************************************************************************/
/* hashtable_change
 *
 * function to change the value associated with a key, where there already
 * exists a value bound to the key in the hashtable.
 * Source due to Holger Schemel.
 * 
 *  */
int
hashtable_change(struct hashtable *h, void *k, void *v)
{
    struct entry *e;
    unsigned int hashvalue, index;
    hashvalue = hash(h,k);
    index = indexFor(h->tablelength,hashvalue);
    e = h->table[index];
    while (NULL != e)
    {
        /* Check hash value to short circuit heavier comparison */
        if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
        {
            free(e->v);
            e->v = v;
            return -1;
        }
        e = e->next;
    }
    return 0;
}

/*
 * Copyright (c) 2002, Christopher Clark
 * 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.
 * 
 * * Neither the name of the original author; nor the names of any contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 * 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 COPYRIGHT OWNER
 * OR CONTRIBUTORS 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.
*/