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 "mdvi.h"
  20
  21 /* simple hash tables for MDVI */
  22
  23
  24 struct _DviHashBucket {
  25         DviHashBucket *next;
  26         DviHashKey      key;
  27         Ulong   hvalue;
  28         void    *data;
  29 };
  30
  31 static Ulong hash_string(DviHashKey key)
  32 {
  33         Uchar   *p;
  34         Ulong   h, g;
  35
  36         for(h = 0, p = (Uchar *)key; *p; p++) {
  37                 h = (h << 4UL) + *p;
  38                 if((g = h & 0xf0000000L) != 0) {
  39                         h ^= (g >> 24UL);
  40                         h ^= g;
  41                 }
  42         }
  43
  44         return h;
  45 }
  46
  47 static int hash_compare(DviHashKey k1, DviHashKey k2)
  48 {
  49         return strcmp((char *)k1, (char *)k2);
  50 }
  51
  52 void    mdvi_hash_init(DviHashTable *hash)
  53 {
  54         hash->buckets = NULL;
  55         hash->nbucks  = 0;
  56         hash->nkeys   = 0;
  57         hash->hash_func = NULL;
  58         hash->hash_comp = NULL;
  59         hash->hash_free = NULL;
  60 }
  61
  62 void    mdvi_hash_create(DviHashTable *hash, int size)
  63 {
  64         int     i;
  65
  66         hash->nbucks = size;
  67         hash->buckets = xnalloc(DviHashBucket *, size);
  68         for(i = 0; i < size; i++)
  69                 hash->buckets[i] = NULL;
  70         hash->hash_func = hash_string;
  71         hash->hash_comp = hash_compare;
  72         hash->hash_free = NULL;
  73         hash->nkeys = 0;
  74 }
  75
  76 static DviHashBucket *hash_find(DviHashTable *hash, DviHashKey key)
  77 {
  78         Ulong   hval;
  79         DviHashBucket *buck;
  80
  81         hval = (hash->hash_func(key) % hash->nbucks);
  82
  83         for(buck = hash->buckets[hval]; buck; buck = buck->next)
  84                 if(hash->hash_comp(buck->key, key) == 0)
  85                         break;
  86         return buck;
  87 }
  88
  89 /* Neither keys nor data are duplicated */
  90 int     mdvi_hash_add(DviHashTable *hash, DviHashKey key, void *data, int rep)
  91 {
  92         DviHashBucket *buck = NULL;
  93         Ulong   hval;
  94
  95         if(rep != MDVI_HASH_UNCHECKED) {
  96                 buck = hash_find(hash, key);
  97                 if(buck != NULL) {
  98                         if(buck->data == data)
  99                                 return 0;
 100                         if(rep == MDVI_HASH_UNIQUE)
 101                                 return -1;
 102                         if(hash->hash_free != NULL)
 103                                 hash->hash_free(buck->key, buck->data);
 104                 }
 105         }
 106         if(buck == NULL) {
 107                 buck = xalloc(DviHashBucket);
 108                 buck->hvalue = hash->hash_func(key);
 109                 hval = (buck->hvalue % hash->nbucks);
 110                 buck->next = hash->buckets[hval];
 111                 hash->buckets[hval] = buck;
 112                 hash->nkeys++;
 113         }
 114
 115         /* save key and data */
 116         buck->key = key;
 117         buck->data = data;
 118
 119         return 0;
 120 }
 121
 122 void    *mdvi_hash_lookup(DviHashTable *hash, DviHashKey key)
 123 {
 124         DviHashBucket *buck = hash_find(hash, key);
 125
 126         return buck ? buck->data : NULL;
 127 }
 128
 129 static DviHashBucket *hash_remove(DviHashTable *hash, DviHashKey key)
 130 {
 131         DviHashBucket *buck, *last;
 132         Ulong   hval;
 133
 134         hval = hash->hash_func(key);
 135         hval %= hash->nbucks;
 136
 137         for(last = NULL, buck = hash->buckets[hval]; buck; buck = buck->next) {
 138                 if(hash->hash_comp(buck->key, key) == 0)
 139                         break;
 140                 last = buck;
 141         }
 142         if(buck == NULL)
 143                 return NULL;
 144         if(last)
 145                 last->next = buck->next;
 146         else
 147                 hash->buckets[hval] = buck->next;
 148         hash->nkeys--;
 149         return buck;
 150 }
 151
 152 void    *mdvi_hash_remove(DviHashTable *hash, DviHashKey key)
 153 {
 154         DviHashBucket *buck = hash_remove(hash, key);
 155         void    *data = NULL;
 156
 157         if(buck) {
 158                 data = buck->data;
 159                 mdvi_free(buck);
 160         }
 161         return data;
 162 }
 163
 164 void    *mdvi_hash_remove_ptr(DviHashTable *hash, DviHashKey key)
 165 {
 166         DviHashBucket *buck, *last;
 167         Ulong   hval;
 168         void    *ptr;
 169
 170         hval = hash->hash_func(key);
 171         hval %= hash->nbucks;
 172
 173         for(last = NULL, buck = hash->buckets[hval]; buck; buck = buck->next) {
 174                 if(buck->key == key)
 175                         break;
 176                 last = buck;
 177         }
 178         if(buck == NULL)
 179                 return NULL;
 180         if(last)
 181                 last->next = buck->next;
 182         else
 183                 hash->buckets[hval] = buck->next;
 184         hash->nkeys--;
 185         /* destroy the bucket */
 186         ptr = buck->data;
 187         mdvi_free(buck);
 188         return ptr;
 189 }
 190
 191 int     mdvi_hash_destroy_key(DviHashTable *hash, DviHashKey key)
 192 {
 193         DviHashBucket *buck = hash_remove(hash, key);
 194
 195         if(buck == NULL)
 196                 return -1;
 197         if(hash->hash_free)
 198                 hash->hash_free(buck->key, buck->data);
 199         mdvi_free(buck);
 200         return 0;
 201 }
 202
 203 void    mdvi_hash_reset(DviHashTable *hash, int reuse)
 204 {
 205         int     i;
 206         DviHashBucket *buck;
 207
 208         /* remove all keys in the hash table */
 209         for(i = 0; i < hash->nbucks; i++) {
 210                 for(; (buck = hash->buckets[i]); ) {
 211                         hash->buckets[i] = buck->next;
 212                         if(hash->hash_free)
 213                                 hash->hash_free(buck->key, buck->data);
 214                         mdvi_free(buck);
 215                 }
 216         }
 217         hash->nkeys = 0;
 218         if(!reuse && hash->buckets) {
 219                 mdvi_free(hash->buckets);
 220                 hash->buckets = NULL;
 221                 hash->nbucks = 0;
 222         } /* otherwise, it is left empty, ready to be reused */
 223 }