| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: sym.c,v 1.8 1999/08/02 14:45:48 mdw Exp $ |
| 4 | * |
| 5 | * Symbol table management |
| 6 | * |
| 7 | * (c) 1998 Straylight/Edgeware |
| 8 | */ |
| 9 | |
| 10 | /*----- Licensing notice --------------------------------------------------* |
| 11 | * |
| 12 | * This file is part of the mLib utilities library. |
| 13 | * |
| 14 | * mLib is free software; you can redistribute it and/or modify |
| 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 | * |
| 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 |
| 22 | * GNU Library General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU Library General Public |
| 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. |
| 28 | */ |
| 29 | |
| 30 | /*----- Revision history --------------------------------------------------* |
| 31 | * |
| 32 | * $Log: sym.c,v $ |
| 33 | * Revision 1.8 1999/08/02 14:45:48 mdw |
| 34 | * Break low-level hashtable code out from sym. |
| 35 | * |
| 36 | * Revision 1.7 1999/06/01 09:49:08 mdw |
| 37 | * Allow things to be looked up by just their caller-supplied hashes. This |
| 38 | * actually needs to be thought through better. |
| 39 | * |
| 40 | * Revision 1.6 1999/05/26 21:08:31 mdw |
| 41 | * Rename symbols in line with newer conventions. |
| 42 | * |
| 43 | * Revision 1.5 1999/05/13 22:48:37 mdw |
| 44 | * Twiddle the extension threshold. Change `-ise' to `-ize' throughout. |
| 45 | * |
| 46 | * Revision 1.4 1999/05/06 19:51:35 mdw |
| 47 | * Reformatted the LGPL notice a little bit. |
| 48 | * |
| 49 | * Revision 1.3 1999/05/05 18:50:31 mdw |
| 50 | * Change licensing conditions to LGPL. |
| 51 | * |
| 52 | * Revision 1.2 1998/11/26 19:27:33 mdw |
| 53 | * Move SYM_NAME into the header file. Fix bugs. |
| 54 | * |
| 55 | * Revision 1.1.1.1 1998/06/17 23:44:42 mdw |
| 56 | * Initial version of mLib |
| 57 | * |
| 58 | */ |
| 59 | |
| 60 | /*----- Header files ------------------------------------------------------*/ |
| 61 | |
| 62 | /* --- ANSI headers --- */ |
| 63 | |
| 64 | #include <stdio.h> |
| 65 | #include <stdlib.h> |
| 66 | #include <string.h> |
| 67 | |
| 68 | /* --- Local headers --- */ |
| 69 | |
| 70 | #include "alloc.h" |
| 71 | #include "bits.h" |
| 72 | #include "crc32.h" |
| 73 | #include "exc.h" |
| 74 | #include "hash.h" |
| 75 | #include "sub.h" |
| 76 | #include "sym.h" |
| 77 | #include "track.h" |
| 78 | |
| 79 | /*----- Tuning parameters -------------------------------------------------*/ |
| 80 | |
| 81 | /* --- Initial hash table size --- * |
| 82 | * |
| 83 | * This is the initial @mask@ value. It must be of the form %$2^n - 1$%, |
| 84 | * so that it can be used to mask of the bottom bits of a hash value. |
| 85 | */ |
| 86 | |
| 87 | #define SYM_INITSZ 64 /* Size of a new hash table */ |
| 88 | |
| 89 | /* --- Maximum load factor --- * |
| 90 | * |
| 91 | * This parameter controls how much the table has to be loaded before the |
| 92 | * table is extended. The number of elements %$n$%, the number of bins %$b$% |
| 93 | * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is |
| 94 | * added to the table and this relation is found to be false, the table is |
| 95 | * doubled in size. |
| 96 | */ |
| 97 | |
| 98 | #define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */ |
| 99 | |
| 100 | /*----- Main code ---------------------------------------------------------*/ |
| 101 | |
| 102 | /* --- @sym_create@ --- * |
| 103 | * |
| 104 | * Arguments: @sym_table *t@ = symbol table to initialize |
| 105 | * |
| 106 | * Returns: --- |
| 107 | * |
| 108 | * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if |
| 109 | * there isn't enough memory. |
| 110 | */ |
| 111 | |
| 112 | void sym_create(sym_table *t) |
| 113 | { |
| 114 | TRACK_CTX("symbol table creation"); |
| 115 | TRACK_PUSH; |
| 116 | hash_create(&t->t, SYM_INITSZ); |
| 117 | t->load = SYM_LIMIT(SYM_INITSZ); |
| 118 | TRACK_POP; |
| 119 | } |
| 120 | |
| 121 | /* --- @sym_destroy@ --- * |
| 122 | * |
| 123 | * Arguments: @sym_table *t@ = pointer to symbol table in question |
| 124 | * |
| 125 | * Returns: --- |
| 126 | * |
| 127 | * Use: Destroys a symbol table, freeing all the memory it used to |
| 128 | * occupy. |
| 129 | */ |
| 130 | |
| 131 | void sym_destroy(sym_table *t) |
| 132 | { |
| 133 | sym_iter i; |
| 134 | |
| 135 | TRACK_CTX("symbol table destruction"); |
| 136 | TRACK_PUSH; |
| 137 | |
| 138 | SYM_MKITER(&i, t); |
| 139 | for (;;) { |
| 140 | sym_base *p; |
| 141 | SYM_NEXT(&i, p); |
| 142 | if (!p) |
| 143 | break; |
| 144 | if (p->len > SYM_BUFSZ) |
| 145 | sub_free(p->name.p, p->len); |
| 146 | free(p); |
| 147 | } |
| 148 | hash_destroy(&t->t); |
| 149 | |
| 150 | TRACK_POP; |
| 151 | } |
| 152 | |
| 153 | /* --- @sym_find@ --- * |
| 154 | * |
| 155 | * Arguments: @sym_table *t@ = pointer to symbol table in question |
| 156 | * @const char *n@ = pointer to symbol table to look up |
| 157 | * @long l@ = length of the name string or negative to measure |
| 158 | * @size_t sz@ = size of desired symbol object, or zero |
| 159 | * @unsigned *f@ = pointer to a flag, or null. |
| 160 | * |
| 161 | * Returns: The address of a @sym_base@ structure, or null if not found |
| 162 | * and @sz@ is zero. |
| 163 | * |
| 164 | * Use: Looks up a symbol in a given symbol table. The name is |
| 165 | * passed by the address of its first character. The length |
| 166 | * may be given, in which case the name may contain arbitrary |
| 167 | * binary data, or it may be given as a negative number, in |
| 168 | * which case the length of the name is calculated as |
| 169 | * @strlen(n) + 1@. |
| 170 | * |
| 171 | * The return value is the address of a pointer to a @sym_base@ |
| 172 | * block (which may have other things on the end, as above). If |
| 173 | * the symbol could be found, the return value points to the |
| 174 | * symbol block. If the symbol wasn't there, then if @sz@ is |
| 175 | * nonzero, a new symbol is created and its address is returned; |
| 176 | * otherwise a null pointer is returned. The exception |
| 177 | * @EXC_NOMEM@ is raised if the block can't be allocated. |
| 178 | * |
| 179 | * The value of @*f@ indicates whether a new symbol entry was |
| 180 | * created: a nonzero value indicates that an old value was |
| 181 | * found. |
| 182 | */ |
| 183 | |
| 184 | void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f) |
| 185 | { |
| 186 | uint32 hash; |
| 187 | size_t len = 0; |
| 188 | hash_base **bin, **p; |
| 189 | sym_base *q; |
| 190 | |
| 191 | /* --- Find the correct bin --- */ |
| 192 | |
| 193 | len = l < 0 ? strlen(n) + 1 : l; |
| 194 | CRC32(hash, 0, n, len); |
| 195 | bin = HASH_BIN(&t->t, hash); |
| 196 | |
| 197 | /* --- Search the bin list --- */ |
| 198 | |
| 199 | for (p = bin; *p; p = &(*p)->next) { |
| 200 | q = (sym_base *)*p; |
| 201 | if (hash == q->b.hash && len == q->len && !memcmp(n, SYM_NAME(q), len)) { |
| 202 | |
| 203 | /* --- Found a match --- * |
| 204 | * |
| 205 | * As a minor, and probably pointless, tweak, move the item to the |
| 206 | * front of its bin list. |
| 207 | */ |
| 208 | |
| 209 | (*p) = q->b.next; |
| 210 | q->b.next = *bin; |
| 211 | *bin = &q->b; |
| 212 | |
| 213 | /* --- Return the block --- */ |
| 214 | |
| 215 | if (f) *f = 1; |
| 216 | return (q); |
| 217 | } |
| 218 | } |
| 219 | |
| 220 | /* --- Couldn't find the item there --- */ |
| 221 | |
| 222 | if (f) *f = 0; |
| 223 | if (!sz) return (0); |
| 224 | |
| 225 | /* --- Create a new symbol block and initialize it --- */ |
| 226 | |
| 227 | { |
| 228 | TRACK_CTX("new symbol creation"); |
| 229 | TRACK_PUSH; |
| 230 | |
| 231 | q = xmalloc(sz); |
| 232 | q->b.next = *bin; |
| 233 | q->b.hash = hash; |
| 234 | q->len = len; |
| 235 | if (n) { |
| 236 | if (len <= SYM_BUFSZ) |
| 237 | memcpy(q->name.b, n, len); |
| 238 | else { |
| 239 | TRY { |
| 240 | q->name.p = sub_alloc(len); |
| 241 | memcpy(q->name.p, n, len); |
| 242 | } CATCH { |
| 243 | free(q); |
| 244 | TRACK_POP; |
| 245 | RETHROW; |
| 246 | } END_TRY; |
| 247 | } |
| 248 | } |
| 249 | |
| 250 | TRACK_POP; |
| 251 | } |
| 252 | |
| 253 | *bin = &q->b; |
| 254 | |
| 255 | /* --- Consider growing the array --- */ |
| 256 | |
| 257 | if (t->load) |
| 258 | t->load--; |
| 259 | if (!t->load && hash_extend(&t->t)) |
| 260 | t->load = SYM_LIMIT(t->t.mask / 2 + 1); |
| 261 | |
| 262 | /* --- Finished that, so return the new symbol block --- */ |
| 263 | |
| 264 | return (q); |
| 265 | } |
| 266 | |
| 267 | /* --- @sym_remove@ --- * |
| 268 | * |
| 269 | * Arguments: @sym_table *i@ = pointer to a symbol table object |
| 270 | * @void *p@ = pointer to symbol table entry |
| 271 | * |
| 272 | * Returns: --- |
| 273 | * |
| 274 | * Use: Removes the object from the symbol table. The space occupied |
| 275 | * by the object and its name is freed; anything else attached |
| 276 | * to the entry should already be gone by this point. |
| 277 | */ |
| 278 | |
| 279 | void sym_remove(sym_table *t, void *p) |
| 280 | { |
| 281 | sym_base *q = p; |
| 282 | hash_remove(&t->t, &q->b); |
| 283 | if (q->len > SYM_BUFSZ) |
| 284 | sub_free(q->name.p, q->len); |
| 285 | free(q); |
| 286 | t->load++; |
| 287 | } |
| 288 | |
| 289 | /* --- @sym_mkiter@ --- * |
| 290 | * |
| 291 | * Arguments: @sym_iter *i@ = pointer to an iterator object |
| 292 | * @sym_table *t@ = pointer to a symbol table object |
| 293 | * |
| 294 | * Returns: --- |
| 295 | * |
| 296 | * Use: Creates a new symbol table iterator which may be used to |
| 297 | * iterate through a symbol table. |
| 298 | */ |
| 299 | |
| 300 | void sym_mkiter(sym_iter *i, sym_table *t) { SYM_MKITER(i, t); } |
| 301 | |
| 302 | /* --- @sym_next@ --- * |
| 303 | * |
| 304 | * Arguments: @sym_iter *i@ = pointer to iterator object |
| 305 | * |
| 306 | * Returns: Pointer to the next symbol found, or null when finished. |
| 307 | * |
| 308 | * Use: Returns the next symbol from the table. Symbols are not |
| 309 | * returned in any particular order. |
| 310 | */ |
| 311 | |
| 312 | void *sym_next(sym_iter *i) |
| 313 | { |
| 314 | void *p; |
| 315 | SYM_NEXT(i, p); |
| 316 | return (p); |
| 317 | } |
| 318 | |
| 319 | /*----- Symbol table test code --------------------------------------------*/ |
| 320 | |
| 321 | #ifdef TEST_RIG |
| 322 | |
| 323 | #include <errno.h> |
| 324 | #include <time.h> |
| 325 | |
| 326 | typedef struct sym_word { |
| 327 | sym_base base; |
| 328 | size_t i; |
| 329 | } sym_word; |
| 330 | |
| 331 | |
| 332 | /* --- What it does --- * |
| 333 | * |
| 334 | * Reads the file /usr/dict/words (change to some other file full of |
| 335 | * interesting and appropriate bits of text to taste) into a big buffer and |
| 336 | * picks apart into lines. Then picks lines at random and enters them into |
| 337 | * the symbol table. |
| 338 | */ |
| 339 | |
| 340 | int main(void) |
| 341 | { |
| 342 | char *buff, *p, *lim; |
| 343 | size_t sz, done; |
| 344 | FILE *fp; |
| 345 | int i; |
| 346 | char **line; |
| 347 | sym_word **flag; |
| 348 | sym_table tbl; |
| 349 | int entries; |
| 350 | |
| 351 | /* --- Initialize for reading the file --- */ |
| 352 | |
| 353 | sz = BUFSIZ; |
| 354 | buff = xmalloc(sz + 1); |
| 355 | done = 0; |
| 356 | sub_init(); |
| 357 | |
| 358 | if ((fp = fopen("/usr/dict/words", "r")) == 0) |
| 359 | fprintf(stderr, "buggered ;-( (%s)\n", strerror(errno)); |
| 360 | |
| 361 | /* --- Read buffers of text --- * |
| 362 | * |
| 363 | * Read a buffer. If more to come, double the buffer size and try again. |
| 364 | * This is the method I recommended to comp.lang.c, so I may as well try |
| 365 | * it. |
| 366 | */ |
| 367 | |
| 368 | for (;;) { |
| 369 | i = fread(buff + done, 1, sz - done, fp); |
| 370 | done += i; |
| 371 | if (done != sz) |
| 372 | break; |
| 373 | sz <<= 1; |
| 374 | buff = xrealloc(buff, sz + 1); |
| 375 | } |
| 376 | |
| 377 | /* --- Count the lines --- */ |
| 378 | |
| 379 | lim = buff + done; |
| 380 | |
| 381 | sz = 1; |
| 382 | for (p = buff; p < lim; p++) |
| 383 | if (*p == '\n') sz++; |
| 384 | |
| 385 | /* --- Build a table of line starts --- */ |
| 386 | |
| 387 | line = xmalloc(sz * sizeof(char *)); |
| 388 | i = 0; |
| 389 | line[i++] = buff; |
| 390 | for (p = buff; p < lim; p++) |
| 391 | if (*p == '\n') *p = 0, line[i++] = p + 1; |
| 392 | *lim = 0; |
| 393 | |
| 394 | /* --- Build a table of lines --- * |
| 395 | * |
| 396 | * This reverses the mapping which the symbol table performs, so that its |
| 397 | * accuracy can be tested. |
| 398 | */ |
| 399 | |
| 400 | flag = xmalloc(sz * sizeof(sym_word *)); |
| 401 | for (i = 0; i < sz; i++) |
| 402 | flag[i] = 0; |
| 403 | entries = 0; |
| 404 | |
| 405 | sym_create(&tbl); |
| 406 | |
| 407 | for (;;) { |
| 408 | i = (unsigned)rand() % sz; |
| 409 | |
| 410 | switch (rand() % 5) |
| 411 | { |
| 412 | case 0: { |
| 413 | sym_word *w; |
| 414 | |
| 415 | printf("? %s\n", line[i]); |
| 416 | |
| 417 | w = sym_find(&tbl, line[i], -1, 0, 0); |
| 418 | if (w != flag[i]) |
| 419 | printf("*** error: find `%s' gave %p not %p\n", |
| 420 | line[i], (void *)w, (void *)flag[i]); |
| 421 | else if (w && w->i != i) |
| 422 | printf("*** error: find sym for `%s' gives index %i not %i\n", |
| 423 | line[i], w->i, i); |
| 424 | } break; |
| 425 | |
| 426 | case 1: { |
| 427 | unsigned f; |
| 428 | sym_word *w; |
| 429 | |
| 430 | printf("+ %s\n", line[i]); |
| 431 | |
| 432 | w = sym_find(&tbl, line[i], -1, sizeof(sym_word), &f); |
| 433 | if (f) |
| 434 | { |
| 435 | if (w != flag[i]) |
| 436 | printf("*** error: create `%s' gave %p not %p\n", |
| 437 | line[i], (void *)w, (void *)flag[i]); |
| 438 | else if (w && w->i != i) |
| 439 | printf("*** error: create sym for `%s' gives index %i not %i\n", |
| 440 | line[i], w->i, i); |
| 441 | } |
| 442 | else |
| 443 | { |
| 444 | if (flag[i]) |
| 445 | printf("*** error: create `%s' gave new block, should be %p\n", |
| 446 | line[i], (void *)flag[i]); |
| 447 | else { |
| 448 | flag[i] = w; |
| 449 | w->i = i; |
| 450 | entries++; |
| 451 | } |
| 452 | } |
| 453 | } break; |
| 454 | |
| 455 | case 2: { |
| 456 | sym_iter it; |
| 457 | sym_word *w, **ntbl; |
| 458 | int v; |
| 459 | |
| 460 | if (!entries) |
| 461 | break; |
| 462 | v = (rand() % entries) == 0; |
| 463 | if (!v) |
| 464 | break; |
| 465 | |
| 466 | printf(".\n"); |
| 467 | |
| 468 | ntbl = xmalloc(sz * sizeof(sym_word *)); |
| 469 | memcpy(ntbl, flag, sz * sizeof(sym_word *)); |
| 470 | sym_mkiter(&it, &tbl); |
| 471 | |
| 472 | while ((w = sym_next(&it)) != 0) { |
| 473 | if (ntbl[w->i] == 0) |
| 474 | printf("*** error: iterate returned duff item %s\n", SYM_NAME(w)); |
| 475 | else { |
| 476 | printf(": %s\n", SYM_NAME(w)); |
| 477 | ntbl[w->i] = 0; |
| 478 | } |
| 479 | } |
| 480 | |
| 481 | for (i = 0; i < sz; i++) |
| 482 | if (ntbl[i]) printf("*** error: iterate didn't return item %s\n", |
| 483 | SYM_NAME(ntbl[i])); |
| 484 | free(ntbl); |
| 485 | } break; |
| 486 | |
| 487 | case 3: { |
| 488 | sym_base *b; |
| 489 | int v = rand() & 255 ? 0 : 1; |
| 490 | break; |
| 491 | |
| 492 | printf("dump\n"); |
| 493 | |
| 494 | for (i = 0; i <= tbl.b.mask; i++) { |
| 495 | if (!tbl.b.v[i]) continue; |
| 496 | if (v) printf(" %i: ", i); |
| 497 | b = (sym_base *)tbl.b.v[i]; |
| 498 | while (b) { |
| 499 | if ((b->b.hash & tbl.b.mask) != i) |
| 500 | printf("*** error: bad hash value found"); |
| 501 | if (v) printf("`%s'(%08lx:%lu) ", |
| 502 | line[((sym_word *)b)->i], |
| 503 | b->b.hash, |
| 504 | b->b.hash & tbl.b.mask); |
| 505 | b = (sym_base *)b->b.next; |
| 506 | } |
| 507 | if (v) putchar('\n'); |
| 508 | } |
| 509 | } break; |
| 510 | |
| 511 | case 4: { |
| 512 | if (flag[i]) { |
| 513 | printf("- %s\n", SYM_NAME(&flag[i]->base)); |
| 514 | if ((rand() & 1023) == 0) { |
| 515 | putchar('-'); fflush(stdout); |
| 516 | } |
| 517 | sym_remove(&tbl, flag[i]); |
| 518 | flag[i] = 0; |
| 519 | entries--; |
| 520 | } |
| 521 | } break; |
| 522 | } |
| 523 | |
| 524 | } |
| 525 | |
| 526 | return (0); |
| 527 | } |
| 528 | |
| 529 | #endif |
| 530 | |
| 531 | /*----- That's all, folks -------------------------------------------------*/ |