shotgun/external_libs/libcchash/hashtable_itr.c

   1 /* Copyright (C) 2002, 2004 Christopher Clark  <firstname.lastname@cl.cam.ac.uk> */
   2
   3 #include "hashtable.h"
   4 #include "hashtable_private.h"
   5 #include "hashtable_itr.h"
   6 #include <stdlib.h> /* defines NULL */
   7
   8 /*****************************************************************************/
   9 /* hashtable_iterator    - iterator constructor */
  10
  11 void
  12 hashtable_iterator_init(struct hashtable_itr *itr, struct hashtable *h)
  13 {
  14     unsigned int i, tablelength;
  15
  16     itr->h = h;
  17     itr->e = NULL;
  18     itr->parent = NULL;
  19     tablelength = h->tablelength;
  20     itr->index = tablelength;
  21     if (0 == h->entrycount) return;
  22
  23     for (i = 0; i < tablelength; i++)
  24     {
  25         if (NULL != h->table[i])
  26         {
  27             itr->e = h->table[i];
  28             itr->index = i;
  29             break;
  30         }
  31     }
  32 }
  33
  34 /*****************************************************************************/
  35 /* key      - return the key of the (key,value) pair at the current position */
  36 /* value    - return the value of the (key,value) pair at the current position */
  37
  38 void *
  39 hashtable_iterator_key(struct hashtable_itr *i)
  40 { return i->e->k; }
  41
  42 void *
  43 hashtable_iterator_value(struct hashtable_itr *i)
  44 { return i->e->v; }
  45
  46 /*****************************************************************************/
  47 /* advance - advance the iterator to the next element
  48  *           returns zero if advanced to end of table */
  49
  50 int
  51 hashtable_iterator_advance(struct hashtable_itr *itr)
  52 {
  53     unsigned int j,tablelength;
  54     struct entry **table;
  55     struct entry *next;
  56     if (NULL == itr->e) return 0; /* stupidity check */
  57
  58     next = itr->e->next;
  59     if (NULL != next)
  60     {
  61         itr->parent = itr->e;
  62         itr->e = next;
  63         return -1;
  64     }
  65     tablelength = itr->h->tablelength;
  66     itr->parent = NULL;
  67     if (tablelength <= (j = ++(itr->index)))
  68     {
  69         itr->e = NULL;
  70         return 0;
  71     }
  72     table = itr->h->table;
  73     while (NULL == (next = table[j]))
  74     {
  75         if (++j >= tablelength)
  76         {
  77             itr->index = tablelength;
  78             itr->e = NULL;
  79             return 0;
  80         }
  81     }
  82     itr->index = j;
  83     itr->e = next;
  84     return -1;
  85 }
  86
  87 /*****************************************************************************/
  88 /* remove - remove the entry at the current iterator position
  89  *          and advance the iterator, if there is a successive
  90  *          element.
  91  *          If you want the value, read it before you remove:
  92  *          beware memory leaks if you don't.
  93  *          Returns zero if end of iteration. */
  94
  95 int
  96 hashtable_iterator_remove(struct hashtable_itr *itr)
  97 {
  98     struct entry *remember_e, *remember_parent;
  99     int ret;
 100
 101     /* Do the removal */
 102     if (NULL == (itr->parent))
 103     {
 104         /* element is head of a chain */
 105         itr->h->table[itr->index] = itr->e->next;
 106     } else {
 107         /* element is mid-chain */
 108         itr->parent->next = itr->e->next;
 109     }
 110     /* itr->e is now outside the hashtable */
 111     remember_e = itr->e;
 112     itr->h->entrycount--;
 113     freekey(remember_e->k);
 114
 115     /* Advance the iterator, correcting the parent */
 116     remember_parent = itr->parent;
 117     ret = hashtable_iterator_advance(itr);
 118     if (itr->parent == remember_e) { itr->parent = remember_parent; }
 119     free(remember_e);
 120     return ret;
 121 }
 122
 123 /*****************************************************************************/
 124 int /* returns zero if not found */
 125 hashtable_iterator_search(struct hashtable_itr *itr,
 126                           struct hashtable *h, void *k)
 127 {
 128     struct entry *e, *parent;
 129     unsigned int hashvalue, index;
 130
 131     hashvalue = hash(h,k);
 132     index = indexFor(h->tablelength,hashvalue);
 133
 134     e = h->table[index];
 135     parent = NULL;
 136     while (NULL != e)
 137     {
 138         /* Check hash value to short circuit heavier comparison */
 139         if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
 140         {
 141             itr->index = index;
 142             itr->e = e;
 143             itr->parent = parent;
 144             itr->h = h;
 145             return -1;
 146         }
 147         parent = e;
 148         e = e->next;
 149     }
 150     return 0;
 151 }
 152
 153
 154 /*
 155  * Copyright (c) 2002, 2004, Christopher Clark
 156  * All rights reserved.
 157  *
 158  * Redistribution and use in source and binary forms, with or without
 159  * modification, are permitted provided that the following conditions
 160  * are met:
 161  *
 162  * * Redistributions of source code must retain the above copyright
 163  * notice, this list of conditions and the following disclaimer.
 164  *
 165  * * Redistributions in binary form must reproduce the above copyright
 166  * notice, this list of conditions and the following disclaimer in the
 167  * documentation and/or other materials provided with the distribution.
 168  *
 169  * * Neither the name of the original author; nor the names of any contributors
 170  * may be used to endorse or promote products derived from this software
 171  * without specific prior written permission.
 172  *
 173  *
 174  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 175  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 176  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 177  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER
 178  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 179  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 180  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 181  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 182  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 183  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 184  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 185 */