| 1 | /* |
| 2 | * This file is part of DisOrder |
| 3 | * Copyright (C) 2005-2008 Richard Kettlewell |
| 4 | * |
| 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. |
| 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 | * |
| 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/>. |
| 17 | */ |
| 18 | /** @file lib/hash.c |
| 19 | * @brief A simple hash table |
| 20 | */ |
| 21 | #include "common.h" |
| 22 | |
| 23 | #include "hash.h" |
| 24 | #include "mem.h" |
| 25 | #include "log.h" |
| 26 | #include "kvp.h" |
| 27 | |
| 28 | /** @brief One entry in a hash table */ |
| 29 | struct entry { |
| 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 */ |
| 34 | }; |
| 35 | |
| 36 | /** @brief A hash table */ |
| 37 | struct hash { |
| 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 */ |
| 42 | }; |
| 43 | |
| 44 | /** @brief Hash function |
| 45 | * @param key Key to hash |
| 46 | * @return Hash code |
| 47 | */ |
| 48 | static size_t hashfn(const char *key) { |
| 49 | size_t i = 0; |
| 50 | |
| 51 | while(*key) |
| 52 | i = 33 * i + (unsigned char)*key++; |
| 53 | return i; |
| 54 | } |
| 55 | |
| 56 | /** @brief Expand a hash table |
| 57 | * @param h Hash table to expand |
| 58 | */ |
| 59 | static void grow(hash *h) { |
| 60 | size_t n, newnslots; |
| 61 | struct entry **newslots, *e, *f; |
| 62 | |
| 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) { |
| 69 | f = e->next; |
| 70 | e->next = newslots[e->h & (newnslots - 1)]; |
| 71 | newslots[e->h & (newnslots - 1)] = e; |
| 72 | } |
| 73 | } |
| 74 | h->slots = newslots; |
| 75 | h->nslots = newnslots; |
| 76 | } |
| 77 | |
| 78 | /** @brief Create a new hash table |
| 79 | * @param valuesize Size of value type |
| 80 | * @return Hash table |
| 81 | */ |
| 82 | hash *hash_new(size_t valuesize) { |
| 83 | hash *h = xmalloc(sizeof *h); |
| 84 | |
| 85 | h->nslots = 256; |
| 86 | h->slots = xcalloc(h->nslots, sizeof (struct slot *)); |
| 87 | h->valuesize = valuesize; |
| 88 | return h; |
| 89 | } |
| 90 | |
| 91 | /** @brief Add an element to a hash table |
| 92 | * @param h Hash table |
| 93 | * @param key Key |
| 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 |
| 97 | * |
| 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 |
| 102 | */ |
| 103 | int hash_add(hash *h, const char *key, const void *value, int mode) { |
| 104 | size_t n = hashfn(key); |
| 105 | struct entry *e; |
| 106 | |
| 107 | for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next) |
| 108 | if(e->h == n || !strcmp(e->key, key)) |
| 109 | break; |
| 110 | if(e) { |
| 111 | /* This key is already present. */ |
| 112 | if(mode == HASH_INSERT) return -1; |
| 113 | if(value) memcpy(e->value, value, h->valuesize); |
| 114 | return 0; |
| 115 | } else { |
| 116 | /* This key is absent. */ |
| 117 | if(mode == HASH_REPLACE) return -1; |
| 118 | if(h->nitems >= h->nslots) /* bound mean chain length */ |
| 119 | grow(h); |
| 120 | e = xmalloc(sizeof *e); |
| 121 | e->next = h->slots[n & (h->nslots - 1)]; |
| 122 | e->h = n; |
| 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; |
| 127 | ++h->nitems; |
| 128 | return 0; |
| 129 | } |
| 130 | } |
| 131 | |
| 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 |
| 136 | */ |
| 137 | int hash_remove(hash *h, const char *key) { |
| 138 | size_t n = hashfn(key); |
| 139 | struct entry *e, **ee; |
| 140 | |
| 141 | for(ee = &h->slots[n & (h->nslots - 1)]; (e = *ee); ee = &e->next) |
| 142 | if(e->h == n || !strcmp(e->key, key)) |
| 143 | break; |
| 144 | if(e) { |
| 145 | *ee = e->next; |
| 146 | --h->nitems; |
| 147 | return 0; |
| 148 | } else |
| 149 | return -1; |
| 150 | } |
| 151 | |
| 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 |
| 156 | * |
| 157 | * The return value points inside the hash table and should not be modified. |
| 158 | */ |
| 159 | void *hash_find(hash *h, const char *key) { |
| 160 | size_t n = hashfn(key); |
| 161 | struct entry *e; |
| 162 | |
| 163 | for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next) |
| 164 | if(e->h == n || !strcmp(e->key, key)) |
| 165 | return e->value; |
| 166 | return 0; |
| 167 | } |
| 168 | |
| 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 |
| 174 | * |
| 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 |
| 177 | * modified. |
| 178 | * |
| 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. |
| 181 | * |
| 182 | * No particular ordering is used. |
| 183 | */ |
| 184 | int hash_foreach(hash *h, |
| 185 | int (*callback)(const char *key, void *value, void *u), |
| 186 | void *u) { |
| 187 | size_t n; |
| 188 | int ret; |
| 189 | struct entry *e, *f; |
| 190 | |
| 191 | for(n = 0; n < h->nslots; ++n) |
| 192 | for(e = h->slots[n]; e; e = f) { |
| 193 | f = e->next; |
| 194 | if((ret = callback(e->key, e->value, u))) |
| 195 | return ret; |
| 196 | } |
| 197 | return 0; |
| 198 | } |
| 199 | |
| 200 | /** @brief Count the size of a hash table |
| 201 | * @param h Hash table |
| 202 | * @return Number of elements in hash table |
| 203 | */ |
| 204 | size_t hash_count(hash *h) { |
| 205 | return h->nitems; |
| 206 | } |
| 207 | |
| 208 | /** @brief Get all the keys of a hash table |
| 209 | * @param h Hash table |
| 210 | * @return NULL-terminated list of keys |
| 211 | * |
| 212 | * The keys point into the hash table itself and should not be modified. |
| 213 | * |
| 214 | * No particular ordering is used. |
| 215 | */ |
| 216 | char **hash_keys(hash *h) { |
| 217 | size_t n; |
| 218 | char **vec = xcalloc(h->nitems + 1, sizeof (char *)), **vp = vec; |
| 219 | struct entry *e; |
| 220 | |
| 221 | for(n = 0; n < h->nslots; ++n) |
| 222 | for(e = h->slots[n]; e; e = e->next) |
| 223 | *vp++ = (char *)e->key; |
| 224 | *vp = 0; |
| 225 | return vec; |
| 226 | } |
| 227 | |
| 228 | /* |
| 229 | Local Variables: |
| 230 | c-basic-offset:2 |
| 231 | comment-column:40 |
| 232 | fill-column:79 |
| 233 | indent-tabs-mode:nil |
| 234 | End: |
| 235 | */ |