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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sym.c,v 1.8 1999/08/02 14:45:48 mdw Exp $ |
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4 | * |
5 | * Symbol table management |
6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
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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 | * |
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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 |
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22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
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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. |
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28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: sym.c,v $ |
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33 | * Revision 1.8 1999/08/02 14:45:48 mdw |
34 | * Break low-level hashtable code out from sym. |
35 | * |
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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 | * |
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40 | * Revision 1.6 1999/05/26 21:08:31 mdw |
41 | * Rename symbols in line with newer conventions. |
42 | * |
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43 | * Revision 1.5 1999/05/13 22:48:37 mdw |
44 | * Twiddle the extension threshold. Change `-ise' to `-ize' throughout. |
45 | * |
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46 | * Revision 1.4 1999/05/06 19:51:35 mdw |
47 | * Reformatted the LGPL notice a little bit. |
48 | * |
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49 | * Revision 1.3 1999/05/05 18:50:31 mdw |
50 | * Change licensing conditions to LGPL. |
51 | * |
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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 |
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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" |
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71 | #include "bits.h" |
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72 | #include "crc32.h" |
73 | #include "exc.h" |
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74 | #include "hash.h" |
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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 | |
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87 | #define SYM_INITSZ 64 /* Size of a new hash table */ |
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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. |
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96 | */ |
97 | |
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98 | #define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */ |
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99 | |
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100 | /*----- Main code ---------------------------------------------------------*/ |
101 | |
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102 | /* --- @sym_create@ --- * |
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103 | * |
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104 | * Arguments: @sym_table *t@ = symbol table to initialize |
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105 | * |
106 | * Returns: --- |
107 | * |
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108 | * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if |
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109 | * there isn't enough memory. |
110 | */ |
111 | |
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112 | void sym_create(sym_table *t) |
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113 | { |
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114 | TRACK_CTX("symbol table creation"); |
115 | TRACK_PUSH; |
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116 | hash_create(&t->t, SYM_INITSZ); |
117 | t->load = SYM_LIMIT(SYM_INITSZ); |
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118 | TRACK_POP; |
119 | } |
120 | |
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121 | /* --- @sym_destroy@ --- * |
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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 | |
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131 | void sym_destroy(sym_table *t) |
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132 | { |
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133 | sym_iter i; |
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134 | |
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135 | TRACK_CTX("symbol table destruction"); |
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136 | TRACK_PUSH; |
137 | |
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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); |
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147 | } |
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148 | hash_destroy(&t->t); |
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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 |
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169 | * @strlen(n) + 1@. |
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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 | { |
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186 | uint32 hash; |
187 | size_t len = 0; |
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188 | hash_base **bin, **p; |
189 | sym_base *q; |
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190 | |
191 | /* --- Find the correct bin --- */ |
192 | |
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193 | len = l < 0 ? strlen(n) + 1 : l; |
194 | CRC32(hash, 0, n, len); |
195 | bin = HASH_BIN(&t->t, hash); |
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196 | |
197 | /* --- Search the bin list --- */ |
198 | |
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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 | |
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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 | |
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209 | (*p) = q->b.next; |
210 | q->b.next = *bin; |
211 | *bin = &q->b; |
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212 | |
213 | /* --- Return the block --- */ |
214 | |
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215 | if (f) *f = 1; |
216 | return (q); |
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217 | } |
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218 | } |
219 | |
220 | /* --- Couldn't find the item there --- */ |
221 | |
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222 | if (f) *f = 0; |
223 | if (!sz) return (0); |
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224 | |
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225 | /* --- Create a new symbol block and initialize it --- */ |
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226 | |
227 | { |
228 | TRACK_CTX("new symbol creation"); |
229 | TRACK_PUSH; |
230 | |
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231 | q = xmalloc(sz); |
232 | q->b.next = *bin; |
233 | q->b.hash = hash; |
234 | q->len = len; |
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235 | if (n) { |
236 | if (len <= SYM_BUFSZ) |
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237 | memcpy(q->name.b, n, len); |
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238 | else { |
239 | TRY { |
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240 | q->name.p = sub_alloc(len); |
241 | memcpy(q->name.p, n, len); |
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242 | } CATCH { |
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243 | free(q); |
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244 | TRACK_POP; |
245 | RETHROW; |
246 | } END_TRY; |
247 | } |
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248 | } |
249 | |
250 | TRACK_POP; |
251 | } |
252 | |
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253 | *bin = &q->b; |
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254 | |
255 | /* --- Consider growing the array --- */ |
256 | |
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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); |
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261 | |
262 | /* --- Finished that, so return the new symbol block --- */ |
263 | |
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264 | return (q); |
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265 | } |
266 | |
267 | /* --- @sym_remove@ --- * |
268 | * |
269 | * Arguments: @sym_table *i@ = pointer to a symbol table object |
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270 | * @void *p@ = pointer to symbol table entry |
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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 | |
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279 | void sym_remove(sym_table *t, void *p) |
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280 | { |
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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++; |
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287 | } |
288 | |
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289 | /* --- @sym_mkiter@ --- * |
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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 | |
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300 | void sym_mkiter(sym_iter *i, sym_table *t) { SYM_MKITER(i, t); } |
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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 | { |
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314 | void *p; |
315 | SYM_NEXT(i, p); |
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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 | |
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351 | /* --- Initialize for reading the file --- */ |
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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 | |
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405 | sym_create(&tbl); |
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406 | |
407 | for (;;) { |
408 | i = (unsigned)rand() % sz; |
409 | |
410 | switch (rand() % 5) |
411 | { |
412 | case 0: { |
413 | sym_word *w; |
414 | |
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415 | printf("? %s\n", line[i]); |
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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 | |
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430 | printf("+ %s\n", line[i]); |
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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; |
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465 | |
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466 | printf(".\n"); |
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467 | |
468 | ntbl = xmalloc(sz * sizeof(sym_word *)); |
469 | memcpy(ntbl, flag, sz * sizeof(sym_word *)); |
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470 | sym_mkiter(&it, &tbl); |
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471 | |
472 | while ((w = sym_next(&it)) != 0) { |
473 | if (ntbl[w->i] == 0) |
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474 | printf("*** error: iterate returned duff item %s\n", SYM_NAME(w)); |
475 | else { |
476 | printf(": %s\n", SYM_NAME(w)); |
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477 | ntbl[w->i] = 0; |
03d53b73 |
478 | } |
0875b58f |
479 | } |
480 | |
481 | for (i = 0; i < sz; i++) |
03d53b73 |
482 | if (ntbl[i]) printf("*** error: iterate didn't return item %s\n", |
483 | SYM_NAME(ntbl[i])); |
0875b58f |
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 | |
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494 | for (i = 0; i <= tbl.b.mask; i++) { |
495 | if (!tbl.b.v[i]) continue; |
0875b58f |
496 | if (v) printf(" %i: ", i); |
03d53b73 |
497 | b = (sym_base *)tbl.b.v[i]; |
0875b58f |
498 | while (b) { |
03d53b73 |
499 | if ((b->b.hash & tbl.b.mask) != i) |
0875b58f |
500 | printf("*** error: bad hash value found"); |
501 | if (v) printf("`%s'(%08lx:%lu) ", |
502 | line[((sym_word *)b)->i], |
03d53b73 |
503 | b->b.hash, |
504 | b->b.hash & tbl.b.mask); |
505 | b = (sym_base *)b->b.next; |
0875b58f |
506 | } |
507 | if (v) putchar('\n'); |
508 | } |
509 | } break; |
510 | |
511 | case 4: { |
512 | if (flag[i]) { |
03d53b73 |
513 | printf("- %s\n", SYM_NAME(&flag[i]->base)); |
0875b58f |
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 -------------------------------------------------*/ |