2 * This file is part of DisOrder
3 * Copyright (C) 2005-2008 Richard Kettlewell
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, either version 3 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
19 * @brief A simple hash table
28 /** @brief One entry in a hash table */
30 struct entry *next; /* next entry same key */
31 size_t h; /* hash of KEY */
32 const char *key; /* key of this entry */
33 void *value; /* value of this entry */
36 /** @brief A hash table */
38 size_t nslots; /* number of slots */
39 size_t nitems; /* total number of entries */
40 struct entry **slots; /* table of slots */
41 size_t valuesize; /* size of a value */
44 /** @brief Hash function
45 * @param key Key to hash
48 static size_t hashfn(const char *key) {
52 i = 33 * i + (unsigned char)*key++;
56 /** @brief Expand a hash table
57 * @param h Hash table to expand
59 static void grow(hash *h) {
61 struct entry **newslots, *e, *f;
63 /* Allocate a new, larger array */
64 newnslots = 2 * h->nslots;
65 newslots = xcalloc(newnslots, sizeof (struct entry *));
66 /* Copy everything to it */
67 for(n = 0; n < h->nslots; ++n) {
68 for(e = h->slots[n]; e; e = f) {
70 e->next = newslots[e->h & (newnslots - 1)];
71 newslots[e->h & (newnslots - 1)] = e;
75 h->nslots = newnslots;
78 /** @brief Create a new hash table
79 * @param valuesize Size of value type
82 hash *hash_new(size_t valuesize) {
83 hash *h = xmalloc(sizeof *h);
86 h->slots = xcalloc(h->nslots, sizeof (struct slot *));
87 h->valuesize = valuesize;
91 /** @brief Add an element to a hash table
94 * @param value New value (will be shallow-copied)
95 * @param mode Add mode
96 * @return 0 on success, -1 if the value could not be added
98 * Possible add modes are:
99 * - @ref HASH_INSERT - key must not exist yet
100 * - @ref HASH_REPLACE - key must already exist
101 * - @ref HASH_INSERT_OR_REPLACE - key may or may not exist
103 int hash_add(hash *h, const char *key, const void *value, int mode) {
104 size_t n = hashfn(key);
107 for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next)
108 if(e->h == n || !strcmp(e->key, key))
111 /* This key is already present. */
112 if(mode == HASH_INSERT) return -1;
113 if(value) memcpy(e->value, value, h->valuesize);
116 /* This key is absent. */
117 if(mode == HASH_REPLACE) return -1;
118 if(h->nitems >= h->nslots) /* bound mean chain length */
120 e = xmalloc(sizeof *e);
121 e->next = h->slots[n & (h->nslots - 1)];
123 e->key = xstrdup(key);
124 e->value = xmalloc(h->valuesize);
125 if(value) memcpy(e->value, value, h->valuesize);
126 h->slots[n & (h->nslots - 1)] = e;
132 /** @brief Remove an element from a hash table
133 * @param h Hash table
134 * @param key Key to remove
135 * @return 0 on success, -1 if the key wasn't found
137 int hash_remove(hash *h, const char *key) {
138 size_t n = hashfn(key);
139 struct entry *e, **ee;
141 for(ee = &h->slots[n & (h->nslots - 1)]; (e = *ee); ee = &e->next)
142 if(e->h == n || !strcmp(e->key, key))
152 /** @brief Find an item in a hash table
153 * @param h Hash table
154 * @param key Key to find
155 * @return Pointer to value or NULL if not found
157 * The return value points inside the hash table and should not be modified.
159 void *hash_find(hash *h, const char *key) {
160 size_t n = hashfn(key);
163 for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next)
164 if(e->h == n || !strcmp(e->key, key))
169 /** @brief Visit every item in a hash table
170 * @param h Hash Table
171 * @param callback Function to call for each item
172 * @param u Passed to @p callback
173 * @return 0 on completion, else last return from @p callback
175 * @p callback should return 0 to continue or non-0 to stop. The @p key and @p
176 * value pointers passed to it point into the hash table and should not be
179 * It's safe to remove items from inside the callback including the visited
180 * one. It is not safe to add items from inside the callback.
182 * No particular ordering is used.
184 int hash_foreach(hash *h,
185 int (*callback)(const char *key, void *value, void *u),
191 for(n = 0; n < h->nslots; ++n)
192 for(e = h->slots[n]; e; e = f) {
194 if((ret = callback(e->key, e->value, u)))
200 /** @brief Count the size of a hash table
201 * @param h Hash table
202 * @return Number of elements in hash table
204 size_t hash_count(hash *h) {
208 /** @brief Get all the keys of a hash table
209 * @param h Hash table
210 * @return NULL-terminated list of keys
212 * The keys point into the hash table itself and should not be modified.
214 * No particular ordering is used.
216 char **hash_keys(hash *h) {
218 char **vec = xcalloc(h->nitems + 1, sizeof (char *)), **vp = vec;
221 for(n = 0; n < h->nslots; ++n)
222 for(e = h->slots[n]; e; e = e->next)
223 *vp++ = (char *)e->key;