backend/dvi/mdvi-lib/hash.c

   1 /*
   2  * Copyright (C) 2000, Matias Atria
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  */
  18
  19 #include <config.h>
  20 #include "mdvi.h"
  21
  22 /* simple hash tables for MDVI */
  23
  24
  25 struct _DviHashBucket {
  26         DviHashBucket *next;
  27         DviHashKey      key;
  28         Ulong   hvalue;
  29         void    *data;
  30 };
  31
  32 static Ulong hash_string(DviHashKey key)
  33 {
  34         Uchar   *p;
  35         Ulong   h, g;
  36
  37         for(h = 0, p = (Uchar *)key; *p; p++) {
  38                 h = (h << 4UL) + *p;
  39                 if((g = h & 0xf0000000L) != 0) {
  40                         h ^= (g >> 24UL);
  41                         h ^= g;
  42                 }
  43         }
  44
  45         return h;
  46 }
  47
  48 static int hash_compare(DviHashKey k1, DviHashKey k2)
  49 {
  50         return strcmp((char *)k1, (char *)k2);
  51 }
  52
  53 void    mdvi_hash_init(DviHashTable *hash)
  54 {
  55         hash->buckets = NULL;
  56         hash->nbucks  = 0;
  57         hash->nkeys   = 0;
  58         hash->hash_func = NULL;
  59         hash->hash_comp = NULL;
  60         hash->hash_free = NULL;
  61 }
  62
  63 void    mdvi_hash_create(DviHashTable *hash, int size)
  64 {
  65         int     i;
  66
  67         hash->nbucks = size;
  68         hash->buckets = xnalloc(DviHashBucket *, size);
  69         for(i = 0; i < size; i++)
  70                 hash->buckets[i] = NULL;
  71         hash->hash_func = hash_string;
  72         hash->hash_comp = hash_compare;
  73         hash->hash_free = NULL;
  74         hash->nkeys = 0;
  75 }
  76
  77 static DviHashBucket *hash_find(DviHashTable *hash, DviHashKey key)
  78 {
  79         Ulong   hval;
  80         DviHashBucket *buck;
  81
  82         hval = (hash->hash_func(key) % hash->nbucks);
  83
  84         for(buck = hash->buckets[hval]; buck; buck = buck->next)
  85                 if(hash->hash_comp(buck->key, key) == 0)
  86                         break;
  87         return buck;
  88 }
  89
  90 /* Neither keys nor data are duplicated */
  91 int     mdvi_hash_add(DviHashTable *hash, DviHashKey key, void *data, int rep)
  92 {
  93         DviHashBucket *buck = NULL;
  94         Ulong   hval;
  95
  96         if(rep != MDVI_HASH_UNCHECKED) {
  97                 buck = hash_find(hash, key);
  98                 if(buck != NULL) {
  99                         if(buck->data == data)
 100                                 return 0;
 101                         if(rep == MDVI_HASH_UNIQUE)
 102                                 return -1;
 103                         if(hash->hash_free != NULL)
 104                                 hash->hash_free(buck->key, buck->data);
 105                 }
 106         }
 107         if(buck == NULL) {
 108                 buck = xalloc(DviHashBucket);
 109                 buck->hvalue = hash->hash_func(key);
 110                 hval = (buck->hvalue % hash->nbucks);
 111                 buck->next = hash->buckets[hval];
 112                 hash->buckets[hval] = buck;
 113                 hash->nkeys++;
 114         }
 115
 116         /* save key and data */
 117         buck->key = key;
 118         buck->data = data;
 119
 120         return 0;
 121 }
 122
 123 void    *mdvi_hash_lookup(DviHashTable *hash, DviHashKey key)
 124 {
 125         DviHashBucket *buck = hash_find(hash, key);
 126
 127         return buck ? buck->data : NULL;
 128 }
 129
 130 static DviHashBucket *hash_remove(DviHashTable *hash, DviHashKey key)
 131 {
 132         DviHashBucket *buck, *last;
 133         Ulong   hval;
 134
 135         hval = hash->hash_func(key);
 136         hval %= hash->nbucks;
 137
 138         for(last = NULL, buck = hash->buckets[hval]; buck; buck = buck->next) {
 139                 if(hash->hash_comp(buck->key, key) == 0)
 140                         break;
 141                 last = buck;
 142         }
 143         if(buck == NULL)
 144                 return NULL;
 145         if(last)
 146                 last->next = buck->next;
 147         else
 148                 hash->buckets[hval] = buck->next;
 149         hash->nkeys--;
 150         return buck;
 151 }
 152
 153 void    *mdvi_hash_remove(DviHashTable *hash, DviHashKey key)
 154 {
 155         DviHashBucket *buck = hash_remove(hash, key);
 156         void    *data = NULL;
 157
 158         if(buck) {
 159                 data = buck->data;
 160                 mdvi_free(buck);
 161         }
 162         return data;
 163 }
 164
 165 void    *mdvi_hash_remove_ptr(DviHashTable *hash, DviHashKey key)
 166 {
 167         DviHashBucket *buck, *last;
 168         Ulong   hval;
 169         void    *ptr;
 170
 171         hval = hash->hash_func(key);
 172         hval %= hash->nbucks;
 173
 174         for(last = NULL, buck = hash->buckets[hval]; buck; buck = buck->next) {
 175                 if(buck->key == key)
 176                         break;
 177                 last = buck;
 178         }
 179         if(buck == NULL)
 180                 return NULL;
 181         if(last)
 182                 last->next = buck->next;
 183         else
 184                 hash->buckets[hval] = buck->next;
 185         hash->nkeys--;
 186         /* destroy the bucket */
 187         ptr = buck->data;
 188         mdvi_free(buck);
 189         return ptr;
 190 }
 191
 192 int     mdvi_hash_destroy_key(DviHashTable *hash, DviHashKey key)
 193 {
 194         DviHashBucket *buck = hash_remove(hash, key);
 195
 196         if(buck == NULL)
 197                 return -1;
 198         if(hash->hash_free)
 199                 hash->hash_free(buck->key, buck->data);
 200         mdvi_free(buck);
 201         return 0;
 202 }
 203
 204 void    mdvi_hash_reset(DviHashTable *hash, int reuse)
 205 {
 206         int     i;
 207         DviHashBucket *buck;
 208
 209         /* remove all keys in the hash table */
 210         for(i = 0; i < hash->nbucks; i++) {
 211                 for(; (buck = hash->buckets[i]); ) {
 212                         hash->buckets[i] = buck->next;
 213                         if(hash->hash_free)
 214                                 hash->hash_free(buck->key, buck->data);
 215                         mdvi_free(buck);
 216                 }
 217         }
 218         hash->nkeys = 0;
 219         if(!reuse && hash->buckets) {
 220                 mdvi_free(hash->buckets);
 221                 hash->buckets = NULL;
 222                 hash->nbucks = 0;
 223         } /* otherwise, it is left empty, ready to be reused */
 224 }