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460b9539 | 1 | /* |
2 | * This file is part of DisOrder | |
5aff007d | 3 | * Copyright (C) 2005-2008 Richard Kettlewell |
460b9539 | 4 | * |
e7eb3a27 | 5 | * This program is free software: you can redistribute it and/or modify |
460b9539 | 6 | * it under the terms of the GNU General Public License as published by |
e7eb3a27 | 7 | * the Free Software Foundation, either version 3 of the License, or |
460b9539 | 8 | * (at your option) any later version. |
e7eb3a27 RK |
9 | * |
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. | |
14 | * | |
460b9539 | 15 | * You should have received a copy of the GNU General Public License |
e7eb3a27 | 16 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
460b9539 | 17 | */ |
132a5a4a RK |
18 | /** @file lib/hash.c |
19 | * @brief A simple hash table | |
20 | */ | |
05b75f8d | 21 | #include "common.h" |
460b9539 | 22 | |
23 | #include "hash.h" | |
24 | #include "mem.h" | |
25 | #include "log.h" | |
9faa7a88 | 26 | #include "kvp.h" |
460b9539 | 27 | |
28 | struct entry { | |
29 | struct entry *next; /* next entry same key */ | |
30 | size_t h; /* hash of KEY */ | |
31 | const char *key; /* key of this entry */ | |
32 | void *value; /* value of this entry */ | |
33 | }; | |
34 | ||
35 | struct hash { | |
36 | size_t nslots; /* number of slots */ | |
37 | size_t nitems; /* total number of entries */ | |
38 | struct entry **slots; /* table of slots */ | |
39 | size_t valuesize; /* size of a value */ | |
40 | }; | |
41 | ||
34d37b3e RK |
42 | /** @brief Hash function |
43 | * @param key Key to hash | |
44 | * @return Hash code | |
45 | */ | |
460b9539 | 46 | static size_t hashfn(const char *key) { |
47 | size_t i = 0; | |
48 | ||
49 | while(*key) | |
50 | i = 33 * i + (unsigned char)*key++; | |
51 | return i; | |
52 | } | |
53 | ||
34d37b3e RK |
54 | /** @brief Expand a hash table |
55 | * @param h Hash table to expand | |
56 | */ | |
460b9539 | 57 | static void grow(hash *h) { |
58 | size_t n, newnslots; | |
59 | struct entry **newslots, *e, *f; | |
60 | ||
61 | /* Allocate a new, larger array */ | |
62 | newnslots = 2 * h->nslots; | |
63 | newslots = xcalloc(newnslots, sizeof (struct entry *)); | |
64 | /* Copy everything to it */ | |
65 | for(n = 0; n < h->nslots; ++n) { | |
66 | for(e = h->slots[n]; e; e = f) { | |
67 | f = e->next; | |
68 | e->next = newslots[e->h & (newnslots - 1)]; | |
69 | newslots[e->h & (newnslots - 1)] = e; | |
70 | } | |
71 | } | |
72 | h->slots = newslots; | |
73 | h->nslots = newnslots; | |
74 | } | |
75 | ||
34d37b3e RK |
76 | /** @brief Create a new hash table |
77 | * @param valuesize Size of value type | |
78 | * @return Hash table | |
79 | */ | |
460b9539 | 80 | hash *hash_new(size_t valuesize) { |
81 | hash *h = xmalloc(sizeof *h); | |
82 | ||
83 | h->nslots = 256; | |
84 | h->slots = xcalloc(h->nslots, sizeof (struct slot *)); | |
85 | h->valuesize = valuesize; | |
86 | return h; | |
87 | } | |
88 | ||
34d37b3e RK |
89 | /** @brief Add an element to a hash table |
90 | * @param h Hash table | |
91 | * @param key Key | |
92 | * @param value New value (will be shallow-copied) | |
93 | * @param mode Add mode | |
94 | * @return 0 on success, -1 if the value could not be added | |
95 | * | |
96 | * Possible add modes are: | |
97 | * - @ref HASH_INSERT - key must not exist yet | |
98 | * - @ref HASH_REPLACE - key must already exist | |
99 | * - @ref HASH_INSERT_OR_REPLACE - key may or may not exist | |
100 | */ | |
460b9539 | 101 | int hash_add(hash *h, const char *key, const void *value, int mode) { |
102 | size_t n = hashfn(key); | |
103 | struct entry *e; | |
104 | ||
105 | for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next) | |
106 | if(e->h == n || !strcmp(e->key, key)) | |
107 | break; | |
108 | if(e) { | |
109 | /* This key is already present. */ | |
110 | if(mode == HASH_INSERT) return -1; | |
111 | if(value) memcpy(e->value, value, h->valuesize); | |
112 | return 0; | |
113 | } else { | |
114 | /* This key is absent. */ | |
115 | if(mode == HASH_REPLACE) return -1; | |
116 | if(h->nitems >= h->nslots) /* bound mean chain length */ | |
117 | grow(h); | |
118 | e = xmalloc(sizeof *e); | |
119 | e->next = h->slots[n & (h->nslots - 1)]; | |
120 | e->h = n; | |
121 | e->key = xstrdup(key); | |
122 | e->value = xmalloc(h->valuesize); | |
123 | if(value) memcpy(e->value, value, h->valuesize); | |
124 | h->slots[n & (h->nslots - 1)] = e; | |
125 | ++h->nitems; | |
126 | return 0; | |
127 | } | |
128 | } | |
129 | ||
34d37b3e RK |
130 | /** @brief Remove an element from a hash table |
131 | * @param h Hash table | |
132 | * @param key Key to remove | |
133 | * @return 0 on success, -1 if the key wasn't found | |
134 | */ | |
460b9539 | 135 | int hash_remove(hash *h, const char *key) { |
136 | size_t n = hashfn(key); | |
137 | struct entry *e, **ee; | |
138 | ||
139 | for(ee = &h->slots[n & (h->nslots - 1)]; (e = *ee); ee = &e->next) | |
140 | if(e->h == n || !strcmp(e->key, key)) | |
141 | break; | |
142 | if(e) { | |
143 | *ee = e->next; | |
144 | --h->nitems; | |
145 | return 0; | |
146 | } else | |
147 | return -1; | |
148 | } | |
149 | ||
34d37b3e RK |
150 | /** @brief Find an item in a hash table |
151 | * @param h Hash table | |
152 | * @param key Key to find | |
153 | * @return Pointer to value or NULL if not found | |
154 | * | |
155 | * The return value points inside the hash table and should not be modified. | |
156 | */ | |
460b9539 | 157 | void *hash_find(hash *h, const char *key) { |
158 | size_t n = hashfn(key); | |
159 | struct entry *e; | |
160 | ||
161 | for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next) | |
162 | if(e->h == n || !strcmp(e->key, key)) | |
163 | return e->value; | |
164 | return 0; | |
165 | } | |
166 | ||
34d37b3e RK |
167 | /** @brief Visit every item in a hash table |
168 | * @param h Hash Table | |
169 | * @param callback Function to call for each item | |
170 | * @param u Passed to @p callback | |
171 | * @return 0 on completion, else last return from @p callback | |
172 | * | |
173 | * @p callback should return 0 to continue or non-0 to stop. The @p key and @p | |
174 | * value pointers passed to it point into the hash table and should not be | |
175 | * modified. | |
176 | * | |
177 | * It's safe to remove items from inside the callback including the visited | |
178 | * one. It is not safe to add items from inside the callback. | |
179 | * | |
180 | * No particular ordering is used. | |
181 | */ | |
460b9539 | 182 | int hash_foreach(hash *h, |
183 | int (*callback)(const char *key, void *value, void *u), | |
184 | void *u) { | |
185 | size_t n; | |
186 | int ret; | |
187 | struct entry *e, *f; | |
188 | ||
189 | for(n = 0; n < h->nslots; ++n) | |
190 | for(e = h->slots[n]; e; e = f) { | |
191 | f = e->next; | |
192 | if((ret = callback(e->key, e->value, u))) | |
193 | return ret; | |
194 | } | |
195 | return 0; | |
196 | } | |
197 | ||
34d37b3e RK |
198 | /** @brief Count the size of a hash table |
199 | * @param h Hash table | |
200 | * @return Number of elements in hash table | |
201 | */ | |
460b9539 | 202 | size_t hash_count(hash *h) { |
203 | return h->nitems; | |
204 | } | |
205 | ||
34d37b3e RK |
206 | /** @brief Get all the keys of a hash table |
207 | * @param h Hash table | |
208 | * @return NULL-terminated list of keys | |
209 | * | |
210 | * The keys point into the hash table itself and should not be modified. | |
211 | * | |
212 | * No particular ordering is used. | |
213 | */ | |
460b9539 | 214 | char **hash_keys(hash *h) { |
215 | size_t n; | |
216 | char **vec = xcalloc(h->nitems + 1, sizeof (char *)), **vp = vec; | |
217 | struct entry *e; | |
218 | ||
219 | for(n = 0; n < h->nslots; ++n) | |
220 | for(e = h->slots[n]; e; e = e->next) | |
221 | *vp++ = (char *)e->key; | |
222 | *vp = 0; | |
223 | return vec; | |
224 | } | |
225 | ||
226 | /* | |
227 | Local Variables: | |
228 | c-basic-offset:2 | |
229 | comment-column:40 | |
230 | fill-column:79 | |
231 | indent-tabs-mode:nil | |
232 | End: | |
233 | */ |