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Track changes to selbuf interface.
[mLib] / sym.c
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0875b58f 1/* -*-c-*-
2 *
c6e0eaf0 3 * $Id: sym.c,v 1.10 1999/12/10 23:42:04 mdw Exp $
0875b58f 4 *
5 * Symbol table management
6 *
7 * (c) 1998 Straylight/Edgeware
8 */
9
c846879c 10/*----- Licensing notice --------------------------------------------------*
0875b58f 11 *
12 * This file is part of the mLib utilities library.
13 *
14 * mLib is free software; you can redistribute it and/or modify
c846879c 15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
0875b58f 19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
c846879c 22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
0bd98442 25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
0875b58f 28 */
29
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: sym.c,v $
c6e0eaf0 33 * Revision 1.10 1999/12/10 23:42:04 mdw
34 * Change header file guard names.
35 *
cd300147 36 * Revision 1.9 1999/10/22 22:36:37 mdw
37 * New test structure for symbol tables.
38 *
03d53b73 39 * Revision 1.8 1999/08/02 14:45:48 mdw
40 * Break low-level hashtable code out from sym.
41 *
d4d7a053 42 * Revision 1.7 1999/06/01 09:49:08 mdw
43 * Allow things to be looked up by just their caller-supplied hashes. This
44 * actually needs to be thought through better.
45 *
34b97201 46 * Revision 1.6 1999/05/26 21:08:31 mdw
47 * Rename symbols in line with newer conventions.
48 *
a7a37c4a 49 * Revision 1.5 1999/05/13 22:48:37 mdw
50 * Twiddle the extension threshold. Change `-ise' to `-ize' throughout.
51 *
0bd98442 52 * Revision 1.4 1999/05/06 19:51:35 mdw
53 * Reformatted the LGPL notice a little bit.
54 *
c846879c 55 * Revision 1.3 1999/05/05 18:50:31 mdw
56 * Change licensing conditions to LGPL.
57 *
a5d14ede 58 * Revision 1.2 1998/11/26 19:27:33 mdw
59 * Move SYM_NAME into the header file. Fix bugs.
60 *
61 * Revision 1.1.1.1 1998/06/17 23:44:42 mdw
62 * Initial version of mLib
0875b58f 63 *
64 */
65
66/*----- Header files ------------------------------------------------------*/
67
68/* --- ANSI headers --- */
69
70#include <stdio.h>
71#include <stdlib.h>
72#include <string.h>
73
74/* --- Local headers --- */
75
76#include "alloc.h"
d4d7a053 77#include "bits.h"
0875b58f 78#include "crc32.h"
79#include "exc.h"
03d53b73 80#include "hash.h"
0875b58f 81#include "sub.h"
82#include "sym.h"
83#include "track.h"
84
85/*----- Tuning parameters -------------------------------------------------*/
86
87/* --- Initial hash table size --- *
88 *
89 * This is the initial @mask@ value. It must be of the form %$2^n - 1$%,
90 * so that it can be used to mask of the bottom bits of a hash value.
91 */
92
03d53b73 93#define SYM_INITSZ 64 /* Size of a new hash table */
0875b58f 94
95/* --- Maximum load factor --- *
96 *
97 * This parameter controls how much the table has to be loaded before the
98 * table is extended. The number of elements %$n$%, the number of bins %$b$%
99 * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is
100 * added to the table and this relation is found to be false, the table is
101 * doubled in size.
0875b58f 102 */
103
03d53b73 104#define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */
0875b58f 105
0875b58f 106/*----- Main code ---------------------------------------------------------*/
107
34b97201 108/* --- @sym_create@ --- *
0875b58f 109 *
a7a37c4a 110 * Arguments: @sym_table *t@ = symbol table to initialize
0875b58f 111 *
112 * Returns: ---
113 *
a7a37c4a 114 * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if
0875b58f 115 * there isn't enough memory.
116 */
117
34b97201 118void sym_create(sym_table *t)
0875b58f 119{
0875b58f 120 TRACK_CTX("symbol table creation");
121 TRACK_PUSH;
03d53b73 122 hash_create(&t->t, SYM_INITSZ);
123 t->load = SYM_LIMIT(SYM_INITSZ);
0875b58f 124 TRACK_POP;
125}
126
34b97201 127/* --- @sym_destroy@ --- *
0875b58f 128 *
129 * Arguments: @sym_table *t@ = pointer to symbol table in question
130 *
131 * Returns: ---
132 *
133 * Use: Destroys a symbol table, freeing all the memory it used to
134 * occupy.
135 */
136
34b97201 137void sym_destroy(sym_table *t)
0875b58f 138{
03d53b73 139 sym_iter i;
0875b58f 140
03d53b73 141 TRACK_CTX("symbol table destruction");
0875b58f 142 TRACK_PUSH;
143
03d53b73 144 SYM_MKITER(&i, t);
145 for (;;) {
146 sym_base *p;
147 SYM_NEXT(&i, p);
148 if (!p)
149 break;
150 if (p->len > SYM_BUFSZ)
151 sub_free(p->name.p, p->len);
152 free(p);
0875b58f 153 }
03d53b73 154 hash_destroy(&t->t);
0875b58f 155
156 TRACK_POP;
157}
158
159/* --- @sym_find@ --- *
160 *
161 * Arguments: @sym_table *t@ = pointer to symbol table in question
162 * @const char *n@ = pointer to symbol table to look up
163 * @long l@ = length of the name string or negative to measure
164 * @size_t sz@ = size of desired symbol object, or zero
165 * @unsigned *f@ = pointer to a flag, or null.
166 *
167 * Returns: The address of a @sym_base@ structure, or null if not found
168 * and @sz@ is zero.
169 *
170 * Use: Looks up a symbol in a given symbol table. The name is
171 * passed by the address of its first character. The length
172 * may be given, in which case the name may contain arbitrary
173 * binary data, or it may be given as a negative number, in
174 * which case the length of the name is calculated as
03d53b73 175 * @strlen(n) + 1@.
0875b58f 176 *
177 * The return value is the address of a pointer to a @sym_base@
178 * block (which may have other things on the end, as above). If
179 * the symbol could be found, the return value points to the
180 * symbol block. If the symbol wasn't there, then if @sz@ is
181 * nonzero, a new symbol is created and its address is returned;
182 * otherwise a null pointer is returned. The exception
183 * @EXC_NOMEM@ is raised if the block can't be allocated.
184 *
185 * The value of @*f@ indicates whether a new symbol entry was
186 * created: a nonzero value indicates that an old value was
187 * found.
188 */
189
190void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f)
191{
d4d7a053 192 uint32 hash;
193 size_t len = 0;
03d53b73 194 hash_base **bin, **p;
195 sym_base *q;
0875b58f 196
197 /* --- Find the correct bin --- */
198
03d53b73 199 len = l < 0 ? strlen(n) + 1 : l;
200 CRC32(hash, 0, n, len);
201 bin = HASH_BIN(&t->t, hash);
0875b58f 202
203 /* --- Search the bin list --- */
204
03d53b73 205 for (p = bin; *p; p = &(*p)->next) {
206 q = (sym_base *)*p;
207 if (hash == q->b.hash && len == q->len && !memcmp(n, SYM_NAME(q), len)) {
208
0875b58f 209 /* --- Found a match --- *
210 *
211 * As a minor, and probably pointless, tweak, move the item to the
212 * front of its bin list.
213 */
214
03d53b73 215 (*p) = q->b.next;
216 q->b.next = *bin;
217 *bin = &q->b;
0875b58f 218
219 /* --- Return the block --- */
220
d4d7a053 221 if (f) *f = 1;
222 return (q);
0875b58f 223 }
0875b58f 224 }
225
226 /* --- Couldn't find the item there --- */
227
d4d7a053 228 if (f) *f = 0;
229 if (!sz) return (0);
0875b58f 230
a7a37c4a 231 /* --- Create a new symbol block and initialize it --- */
0875b58f 232
233 {
234 TRACK_CTX("new symbol creation");
235 TRACK_PUSH;
236
03d53b73 237 q = xmalloc(sz);
238 q->b.next = *bin;
239 q->b.hash = hash;
240 q->len = len;
d4d7a053 241 if (n) {
242 if (len <= SYM_BUFSZ)
03d53b73 243 memcpy(q->name.b, n, len);
d4d7a053 244 else {
245 TRY {
03d53b73 246 q->name.p = sub_alloc(len);
247 memcpy(q->name.p, n, len);
d4d7a053 248 } CATCH {
03d53b73 249 free(q);
d4d7a053 250 TRACK_POP;
251 RETHROW;
252 } END_TRY;
253 }
0875b58f 254 }
255
256 TRACK_POP;
257 }
258
03d53b73 259 *bin = &q->b;
0875b58f 260
261 /* --- Consider growing the array --- */
262
03d53b73 263 if (t->load)
264 t->load--;
265 if (!t->load && hash_extend(&t->t))
266 t->load = SYM_LIMIT(t->t.mask / 2 + 1);
0875b58f 267
268 /* --- Finished that, so return the new symbol block --- */
269
03d53b73 270 return (q);
0875b58f 271}
272
273/* --- @sym_remove@ --- *
274 *
c6e0eaf0 275 * Arguments: @sym_table *t@ = pointer to a symbol table object
03d53b73 276 * @void *p@ = pointer to symbol table entry
0875b58f 277 *
278 * Returns: ---
279 *
280 * Use: Removes the object from the symbol table. The space occupied
281 * by the object and its name is freed; anything else attached
282 * to the entry should already be gone by this point.
283 */
284
03d53b73 285void sym_remove(sym_table *t, void *p)
0875b58f 286{
03d53b73 287 sym_base *q = p;
288 hash_remove(&t->t, &q->b);
289 if (q->len > SYM_BUFSZ)
290 sub_free(q->name.p, q->len);
291 free(q);
292 t->load++;
0875b58f 293}
294
34b97201 295/* --- @sym_mkiter@ --- *
0875b58f 296 *
297 * Arguments: @sym_iter *i@ = pointer to an iterator object
298 * @sym_table *t@ = pointer to a symbol table object
299 *
300 * Returns: ---
301 *
302 * Use: Creates a new symbol table iterator which may be used to
303 * iterate through a symbol table.
304 */
305
03d53b73 306void sym_mkiter(sym_iter *i, sym_table *t) { SYM_MKITER(i, t); }
0875b58f 307
308/* --- @sym_next@ --- *
309 *
310 * Arguments: @sym_iter *i@ = pointer to iterator object
311 *
312 * Returns: Pointer to the next symbol found, or null when finished.
313 *
314 * Use: Returns the next symbol from the table. Symbols are not
315 * returned in any particular order.
316 */
317
318void *sym_next(sym_iter *i)
319{
03d53b73 320 void *p;
321 SYM_NEXT(i, p);
0875b58f 322 return (p);
323}
324
0875b58f 325/*----- That's all, folks -------------------------------------------------*/