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[disorder] / lib / hash.c
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460b9539 1/*
2 * This file is part of DisOrder
3 * Copyright (C) 2005, 2006 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 2 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, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * 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, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
18 * USA
19 */
20
21#include <config.h>
22#include "types.h"
23
24#include <string.h>
25
26#include "hash.h"
27#include "mem.h"
28#include "log.h"
29
30struct entry {
31 struct entry *next; /* next entry same key */
32 size_t h; /* hash of KEY */
33 const char *key; /* key of this entry */
34 void *value; /* value of this entry */
35};
36
37struct 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
44static size_t hashfn(const char *key) {
45 size_t i = 0;
46
47 while(*key)
48 i = 33 * i + (unsigned char)*key++;
49 return i;
50}
51
52static void grow(hash *h) {
53 size_t n, newnslots;
54 struct entry **newslots, *e, *f;
55
56 /* Allocate a new, larger array */
57 newnslots = 2 * h->nslots;
58 newslots = xcalloc(newnslots, sizeof (struct entry *));
59 /* Copy everything to it */
60 for(n = 0; n < h->nslots; ++n) {
61 for(e = h->slots[n]; e; e = f) {
62 f = e->next;
63 e->next = newslots[e->h & (newnslots - 1)];
64 newslots[e->h & (newnslots - 1)] = e;
65 }
66 }
67 h->slots = newslots;
68 h->nslots = newnslots;
69}
70
71hash *hash_new(size_t valuesize) {
72 hash *h = xmalloc(sizeof *h);
73
74 h->nslots = 256;
75 h->slots = xcalloc(h->nslots, sizeof (struct slot *));
76 h->valuesize = valuesize;
77 return h;
78}
79
80int hash_add(hash *h, const char *key, const void *value, int mode) {
81 size_t n = hashfn(key);
82 struct entry *e;
83
84 for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next)
85 if(e->h == n || !strcmp(e->key, key))
86 break;
87 if(e) {
88 /* This key is already present. */
89 if(mode == HASH_INSERT) return -1;
90 if(value) memcpy(e->value, value, h->valuesize);
91 return 0;
92 } else {
93 /* This key is absent. */
94 if(mode == HASH_REPLACE) return -1;
95 if(h->nitems >= h->nslots) /* bound mean chain length */
96 grow(h);
97 e = xmalloc(sizeof *e);
98 e->next = h->slots[n & (h->nslots - 1)];
99 e->h = n;
100 e->key = xstrdup(key);
101 e->value = xmalloc(h->valuesize);
102 if(value) memcpy(e->value, value, h->valuesize);
103 h->slots[n & (h->nslots - 1)] = e;
104 ++h->nitems;
105 return 0;
106 }
107}
108
109int hash_remove(hash *h, const char *key) {
110 size_t n = hashfn(key);
111 struct entry *e, **ee;
112
113 for(ee = &h->slots[n & (h->nslots - 1)]; (e = *ee); ee = &e->next)
114 if(e->h == n || !strcmp(e->key, key))
115 break;
116 if(e) {
117 *ee = e->next;
118 --h->nitems;
119 return 0;
120 } else
121 return -1;
122}
123
124void *hash_find(hash *h, const char *key) {
125 size_t n = hashfn(key);
126 struct entry *e;
127
128 for(e = h->slots[n & (h->nslots - 1)]; e; e = e->next)
129 if(e->h == n || !strcmp(e->key, key))
130 return e->value;
131 return 0;
132}
133
134int hash_foreach(hash *h,
135 int (*callback)(const char *key, void *value, void *u),
136 void *u) {
137 size_t n;
138 int ret;
139 struct entry *e, *f;
140
141 for(n = 0; n < h->nslots; ++n)
142 for(e = h->slots[n]; e; e = f) {
143 f = e->next;
144 if((ret = callback(e->key, e->value, u)))
145 return ret;
146 }
147 return 0;
148}
149
150size_t hash_count(hash *h) {
151 return h->nitems;
152}
153
154char **hash_keys(hash *h) {
155 size_t n;
156 char **vec = xcalloc(h->nitems + 1, sizeof (char *)), **vp = vec;
157 struct entry *e;
158
159 for(n = 0; n < h->nslots; ++n)
160 for(e = h->slots[n]; e; e = e->next)
161 *vp++ = (char *)e->key;
162 *vp = 0;
163 return vec;
164}
165
166/*
167Local Variables:
168c-basic-offset:2
169comment-column:40
170fill-column:79
171indent-tabs-mode:nil
172End:
173*/
174/* arch-tag:8JLNu2iwue7D0MlS0/nR2g */