]>
Commit | Line | Data |
---|---|---|
fca65d4b FK |
1 | /* |
2 | * This file has been copied from commit e7ac713d^ in the GNU grep git | |
3 | * repository. A few small changes have been made to adapt the code to | |
4 | * Git. | |
5 | */ | |
6 | ||
05f3dbba FK |
7 | /* kwset.c - search for any of a set of keywords. |
8 | Copyright 1989, 1998, 2000, 2005 Free Software Foundation, Inc. | |
9 | ||
10 | This program is free software; you can redistribute it and/or modify | |
11 | it under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation; either version 2, or (at your option) | |
13 | any later version. | |
14 | ||
15 | This program is distributed in the hope that it will be useful, | |
16 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | GNU General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU General Public License | |
48425792 | 21 | along with this program; if not, see <http://www.gnu.org/licenses/>. */ |
05f3dbba FK |
22 | |
23 | /* Written August 1989 by Mike Haertel. | |
24 | The author may be reached (Email) at the address mike@ai.mit.edu, | |
25 | or (US mail) as Mike Haertel c/o Free Software Foundation. */ | |
26 | ||
2fec81cb | 27 | /* The algorithm implemented by these routines bears a startling resemblance |
05f3dbba FK |
28 | to one discovered by Beate Commentz-Walter, although it is not identical. |
29 | See "A String Matching Algorithm Fast on the Average," Technical Report, | |
30 | IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900 | |
31 | Heidelberg, Germany. See also Aho, A.V., and M. Corasick, "Efficient | |
32 | String Matching: An Aid to Bibliographic Search," CACM June 1975, | |
33 | Vol. 18, No. 6, which describes the failure function used below. */ | |
34 | ||
fca65d4b FK |
35 | #include "cache.h" |
36 | ||
05f3dbba | 37 | #include "kwset.h" |
d190a087 | 38 | #include "compat/obstack.h" |
05f3dbba | 39 | |
05f3dbba | 40 | #define NCHAR (UCHAR_MAX + 1) |
08e04506 JS |
41 | /* adapter for `xmalloc()`, which takes `size_t`, not `long` */ |
42 | static void *obstack_chunk_alloc(long size) | |
43 | { | |
44 | if (size < 0) | |
45 | BUG("Cannot allocate a negative amount: %ld", size); | |
46 | return xmalloc(size); | |
47 | } | |
05f3dbba FK |
48 | #define obstack_chunk_free free |
49 | ||
50 | #define U(c) ((unsigned char) (c)) | |
51 | ||
52 | /* Balanced tree of edges and labels leaving a given trie node. */ | |
53 | struct tree | |
54 | { | |
55 | struct tree *llink; /* Left link; MUST be first field. */ | |
56 | struct tree *rlink; /* Right link (to larger labels). */ | |
57 | struct trie *trie; /* Trie node pointed to by this edge. */ | |
58 | unsigned char label; /* Label on this edge. */ | |
59 | char balance; /* Difference in depths of subtrees. */ | |
60 | }; | |
61 | ||
62 | /* Node of a trie representing a set of reversed keywords. */ | |
63 | struct trie | |
64 | { | |
65 | unsigned int accepting; /* Word index of accepted word, or zero. */ | |
66 | struct tree *links; /* Tree of edges leaving this node. */ | |
67 | struct trie *parent; /* Parent of this node. */ | |
68 | struct trie *next; /* List of all trie nodes in level order. */ | |
69 | struct trie *fail; /* Aho-Corasick failure function. */ | |
70 | int depth; /* Depth of this node from the root. */ | |
71 | int shift; /* Shift function for search failures. */ | |
749f763d | 72 | int maxshift; /* Max shift of self and descendants. */ |
05f3dbba FK |
73 | }; |
74 | ||
75 | /* Structure returned opaquely to the caller, containing everything. */ | |
76 | struct kwset | |
77 | { | |
78 | struct obstack obstack; /* Obstack for node allocation. */ | |
79 | int words; /* Number of words in the trie. */ | |
80 | struct trie *trie; /* The trie itself. */ | |
81 | int mind; /* Minimum depth of an accepting node. */ | |
82 | int maxd; /* Maximum depth of any node. */ | |
83 | unsigned char delta[NCHAR]; /* Delta table for rapid search. */ | |
84 | struct trie *next[NCHAR]; /* Table of children of the root. */ | |
85 | char *target; /* Target string if there's only one. */ | |
86 | int mind2; /* Used in Boyer-Moore search for one string. */ | |
189c860c | 87 | unsigned char const *trans; /* Character translation table. */ |
05f3dbba FK |
88 | }; |
89 | ||
90 | /* Allocate and initialize a keyword set object, returning an opaque | |
91 | pointer to it. Return NULL if memory is not available. */ | |
92 | kwset_t | |
189c860c | 93 | kwsalloc (unsigned char const *trans) |
05f3dbba FK |
94 | { |
95 | struct kwset *kwset; | |
96 | ||
fca65d4b | 97 | kwset = (struct kwset *) xmalloc(sizeof (struct kwset)); |
05f3dbba FK |
98 | |
99 | obstack_init(&kwset->obstack); | |
100 | kwset->words = 0; | |
101 | kwset->trie | |
102 | = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie)); | |
103 | if (!kwset->trie) | |
104 | { | |
105 | kwsfree((kwset_t) kwset); | |
106 | return NULL; | |
107 | } | |
108 | kwset->trie->accepting = 0; | |
109 | kwset->trie->links = NULL; | |
110 | kwset->trie->parent = NULL; | |
111 | kwset->trie->next = NULL; | |
112 | kwset->trie->fail = NULL; | |
113 | kwset->trie->depth = 0; | |
114 | kwset->trie->shift = 0; | |
115 | kwset->mind = INT_MAX; | |
116 | kwset->maxd = -1; | |
117 | kwset->target = NULL; | |
118 | kwset->trans = trans; | |
119 | ||
120 | return (kwset_t) kwset; | |
121 | } | |
122 | ||
123 | /* This upper bound is valid for CHAR_BIT >= 4 and | |
124 | exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }. */ | |
125 | #define DEPTH_SIZE (CHAR_BIT + CHAR_BIT/2) | |
126 | ||
127 | /* Add the given string to the contents of the keyword set. Return NULL | |
128 | for success, an error message otherwise. */ | |
129 | const char * | |
130 | kwsincr (kwset_t kws, char const *text, size_t len) | |
131 | { | |
132 | struct kwset *kwset; | |
133 | register struct trie *trie; | |
134 | register unsigned char label; | |
135 | register struct tree *link; | |
136 | register int depth; | |
137 | struct tree *links[DEPTH_SIZE]; | |
138 | enum { L, R } dirs[DEPTH_SIZE]; | |
139 | struct tree *t, *r, *l, *rl, *lr; | |
140 | ||
141 | kwset = (struct kwset *) kws; | |
142 | trie = kwset->trie; | |
143 | text += len; | |
144 | ||
145 | /* Descend the trie (built of reversed keywords) character-by-character, | |
146 | installing new nodes when necessary. */ | |
147 | while (len--) | |
148 | { | |
149 | label = kwset->trans ? kwset->trans[U(*--text)] : *--text; | |
150 | ||
151 | /* Descend the tree of outgoing links for this trie node, | |
152 | looking for the current character and keeping track | |
153 | of the path followed. */ | |
154 | link = trie->links; | |
155 | links[0] = (struct tree *) &trie->links; | |
156 | dirs[0] = L; | |
157 | depth = 1; | |
158 | ||
159 | while (link && label != link->label) | |
160 | { | |
161 | links[depth] = link; | |
162 | if (label < link->label) | |
163 | dirs[depth++] = L, link = link->llink; | |
164 | else | |
165 | dirs[depth++] = R, link = link->rlink; | |
166 | } | |
167 | ||
168 | /* The current character doesn't have an outgoing link at | |
169 | this trie node, so build a new trie node and install | |
170 | a link in the current trie node's tree. */ | |
171 | if (!link) | |
172 | { | |
173 | link = (struct tree *) obstack_alloc(&kwset->obstack, | |
174 | sizeof (struct tree)); | |
175 | if (!link) | |
fca65d4b | 176 | return "memory exhausted"; |
05f3dbba FK |
177 | link->llink = NULL; |
178 | link->rlink = NULL; | |
179 | link->trie = (struct trie *) obstack_alloc(&kwset->obstack, | |
180 | sizeof (struct trie)); | |
181 | if (!link->trie) | |
182 | { | |
183 | obstack_free(&kwset->obstack, link); | |
fca65d4b | 184 | return "memory exhausted"; |
05f3dbba FK |
185 | } |
186 | link->trie->accepting = 0; | |
187 | link->trie->links = NULL; | |
188 | link->trie->parent = trie; | |
189 | link->trie->next = NULL; | |
190 | link->trie->fail = NULL; | |
191 | link->trie->depth = trie->depth + 1; | |
192 | link->trie->shift = 0; | |
193 | link->label = label; | |
194 | link->balance = 0; | |
195 | ||
196 | /* Install the new tree node in its parent. */ | |
197 | if (dirs[--depth] == L) | |
198 | links[depth]->llink = link; | |
199 | else | |
200 | links[depth]->rlink = link; | |
201 | ||
202 | /* Back up the tree fixing the balance flags. */ | |
203 | while (depth && !links[depth]->balance) | |
204 | { | |
205 | if (dirs[depth] == L) | |
206 | --links[depth]->balance; | |
207 | else | |
208 | ++links[depth]->balance; | |
209 | --depth; | |
210 | } | |
211 | ||
212 | /* Rebalance the tree by pointer rotations if necessary. */ | |
213 | if (depth && ((dirs[depth] == L && --links[depth]->balance) | |
214 | || (dirs[depth] == R && ++links[depth]->balance))) | |
215 | { | |
216 | switch (links[depth]->balance) | |
217 | { | |
218 | case (char) -2: | |
219 | switch (dirs[depth + 1]) | |
220 | { | |
221 | case L: | |
222 | r = links[depth], t = r->llink, rl = t->rlink; | |
223 | t->rlink = r, r->llink = rl; | |
224 | t->balance = r->balance = 0; | |
225 | break; | |
226 | case R: | |
227 | r = links[depth], l = r->llink, t = l->rlink; | |
228 | rl = t->rlink, lr = t->llink; | |
229 | t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl; | |
230 | l->balance = t->balance != 1 ? 0 : -1; | |
231 | r->balance = t->balance != (char) -1 ? 0 : 1; | |
232 | t->balance = 0; | |
233 | break; | |
234 | default: | |
235 | abort (); | |
236 | } | |
237 | break; | |
238 | case 2: | |
239 | switch (dirs[depth + 1]) | |
240 | { | |
241 | case R: | |
242 | l = links[depth], t = l->rlink, lr = t->llink; | |
243 | t->llink = l, l->rlink = lr; | |
244 | t->balance = l->balance = 0; | |
245 | break; | |
246 | case L: | |
247 | l = links[depth], r = l->rlink, t = r->llink; | |
248 | lr = t->llink, rl = t->rlink; | |
249 | t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl; | |
250 | l->balance = t->balance != 1 ? 0 : -1; | |
251 | r->balance = t->balance != (char) -1 ? 0 : 1; | |
252 | t->balance = 0; | |
253 | break; | |
254 | default: | |
255 | abort (); | |
256 | } | |
257 | break; | |
258 | default: | |
259 | abort (); | |
260 | } | |
261 | ||
262 | if (dirs[depth - 1] == L) | |
263 | links[depth - 1]->llink = t; | |
264 | else | |
265 | links[depth - 1]->rlink = t; | |
266 | } | |
267 | } | |
268 | ||
269 | trie = link->trie; | |
270 | } | |
271 | ||
272 | /* Mark the node we finally reached as accepting, encoding the | |
273 | index number of this word in the keyword set so far. */ | |
274 | if (!trie->accepting) | |
275 | trie->accepting = 1 + 2 * kwset->words; | |
276 | ++kwset->words; | |
277 | ||
278 | /* Keep track of the longest and shortest string of the keyword set. */ | |
279 | if (trie->depth < kwset->mind) | |
280 | kwset->mind = trie->depth; | |
281 | if (trie->depth > kwset->maxd) | |
282 | kwset->maxd = trie->depth; | |
283 | ||
284 | return NULL; | |
285 | } | |
286 | ||
287 | /* Enqueue the trie nodes referenced from the given tree in the | |
288 | given queue. */ | |
289 | static void | |
290 | enqueue (struct tree *tree, struct trie **last) | |
291 | { | |
292 | if (!tree) | |
293 | return; | |
294 | enqueue(tree->llink, last); | |
295 | enqueue(tree->rlink, last); | |
296 | (*last) = (*last)->next = tree->trie; | |
297 | } | |
298 | ||
299 | /* Compute the Aho-Corasick failure function for the trie nodes referenced | |
300 | from the given tree, given the failure function for their parent as | |
301 | well as a last resort failure node. */ | |
302 | static void | |
303 | treefails (register struct tree const *tree, struct trie const *fail, | |
304 | struct trie *recourse) | |
305 | { | |
306 | register struct tree *link; | |
307 | ||
308 | if (!tree) | |
309 | return; | |
310 | ||
311 | treefails(tree->llink, fail, recourse); | |
312 | treefails(tree->rlink, fail, recourse); | |
313 | ||
314 | /* Find, in the chain of fails going back to the root, the first | |
749f763d | 315 | node that has a descendant on the current label. */ |
05f3dbba FK |
316 | while (fail) |
317 | { | |
318 | link = fail->links; | |
319 | while (link && tree->label != link->label) | |
320 | if (tree->label < link->label) | |
321 | link = link->llink; | |
322 | else | |
323 | link = link->rlink; | |
324 | if (link) | |
325 | { | |
326 | tree->trie->fail = link->trie; | |
327 | return; | |
328 | } | |
329 | fail = fail->fail; | |
330 | } | |
331 | ||
332 | tree->trie->fail = recourse; | |
333 | } | |
334 | ||
335 | /* Set delta entries for the links of the given tree such that | |
336 | the preexisting delta value is larger than the current depth. */ | |
337 | static void | |
338 | treedelta (register struct tree const *tree, | |
339 | register unsigned int depth, | |
340 | unsigned char delta[]) | |
341 | { | |
342 | if (!tree) | |
343 | return; | |
344 | treedelta(tree->llink, depth, delta); | |
345 | treedelta(tree->rlink, depth, delta); | |
346 | if (depth < delta[tree->label]) | |
347 | delta[tree->label] = depth; | |
348 | } | |
349 | ||
350 | /* Return true if A has every label in B. */ | |
351 | static int | |
352 | hasevery (register struct tree const *a, register struct tree const *b) | |
353 | { | |
354 | if (!b) | |
355 | return 1; | |
356 | if (!hasevery(a, b->llink)) | |
357 | return 0; | |
358 | if (!hasevery(a, b->rlink)) | |
359 | return 0; | |
360 | while (a && b->label != a->label) | |
361 | if (b->label < a->label) | |
362 | a = a->llink; | |
363 | else | |
364 | a = a->rlink; | |
365 | return !!a; | |
366 | } | |
367 | ||
368 | /* Compute a vector, indexed by character code, of the trie nodes | |
369 | referenced from the given tree. */ | |
370 | static void | |
371 | treenext (struct tree const *tree, struct trie *next[]) | |
372 | { | |
373 | if (!tree) | |
374 | return; | |
375 | treenext(tree->llink, next); | |
376 | treenext(tree->rlink, next); | |
377 | next[tree->label] = tree->trie; | |
378 | } | |
379 | ||
380 | /* Compute the shift for each trie node, as well as the delta | |
381 | table and next cache for the given keyword set. */ | |
382 | const char * | |
383 | kwsprep (kwset_t kws) | |
384 | { | |
385 | register struct kwset *kwset; | |
386 | register int i; | |
387 | register struct trie *curr; | |
189c860c | 388 | register unsigned char const *trans; |
05f3dbba FK |
389 | unsigned char delta[NCHAR]; |
390 | ||
391 | kwset = (struct kwset *) kws; | |
392 | ||
393 | /* Initial values for the delta table; will be changed later. The | |
394 | delta entry for a given character is the smallest depth of any | |
395 | node at which an outgoing edge is labeled by that character. */ | |
396 | memset(delta, kwset->mind < UCHAR_MAX ? kwset->mind : UCHAR_MAX, NCHAR); | |
397 | ||
398 | /* Check if we can use the simple boyer-moore algorithm, instead | |
399 | of the hairy commentz-walter algorithm. */ | |
400 | if (kwset->words == 1 && kwset->trans == NULL) | |
401 | { | |
402 | char c; | |
403 | ||
404 | /* Looking for just one string. Extract it from the trie. */ | |
405 | kwset->target = obstack_alloc(&kwset->obstack, kwset->mind); | |
406 | if (!kwset->target) | |
fca65d4b | 407 | return "memory exhausted"; |
05f3dbba FK |
408 | for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i) |
409 | { | |
410 | kwset->target[i] = curr->links->label; | |
411 | curr = curr->links->trie; | |
412 | } | |
413 | /* Build the Boyer Moore delta. Boy that's easy compared to CW. */ | |
414 | for (i = 0; i < kwset->mind; ++i) | |
415 | delta[U(kwset->target[i])] = kwset->mind - (i + 1); | |
416 | /* Find the minimal delta2 shift that we might make after | |
417 | a backwards match has failed. */ | |
418 | c = kwset->target[kwset->mind - 1]; | |
419 | for (i = kwset->mind - 2; i >= 0; --i) | |
420 | if (kwset->target[i] == c) | |
421 | break; | |
422 | kwset->mind2 = kwset->mind - (i + 1); | |
423 | } | |
424 | else | |
425 | { | |
426 | register struct trie *fail; | |
427 | struct trie *last, *next[NCHAR]; | |
428 | ||
429 | /* Traverse the nodes of the trie in level order, simultaneously | |
430 | computing the delta table, failure function, and shift function. */ | |
431 | for (curr = last = kwset->trie; curr; curr = curr->next) | |
432 | { | |
749f763d | 433 | /* Enqueue the immediate descendants in the level order queue. */ |
05f3dbba FK |
434 | enqueue(curr->links, &last); |
435 | ||
436 | curr->shift = kwset->mind; | |
437 | curr->maxshift = kwset->mind; | |
438 | ||
749f763d | 439 | /* Update the delta table for the descendants of this node. */ |
05f3dbba FK |
440 | treedelta(curr->links, curr->depth, delta); |
441 | ||
2fec81cb | 442 | /* Compute the failure function for the descendants of this node. */ |
05f3dbba FK |
443 | treefails(curr->links, curr->fail, kwset->trie); |
444 | ||
445 | /* Update the shifts at each node in the current node's chain | |
446 | of fails back to the root. */ | |
447 | for (fail = curr->fail; fail; fail = fail->fail) | |
448 | { | |
449 | /* If the current node has some outgoing edge that the fail | |
450 | doesn't, then the shift at the fail should be no larger | |
451 | than the difference of their depths. */ | |
452 | if (!hasevery(fail->links, curr->links)) | |
453 | if (curr->depth - fail->depth < fail->shift) | |
454 | fail->shift = curr->depth - fail->depth; | |
455 | ||
456 | /* If the current node is accepting then the shift at the | |
749f763d | 457 | fail and its descendants should be no larger than the |
05f3dbba FK |
458 | difference of their depths. */ |
459 | if (curr->accepting && fail->maxshift > curr->depth - fail->depth) | |
460 | fail->maxshift = curr->depth - fail->depth; | |
461 | } | |
462 | } | |
463 | ||
464 | /* Traverse the trie in level order again, fixing up all nodes whose | |
465 | shift exceeds their inherited maxshift. */ | |
466 | for (curr = kwset->trie->next; curr; curr = curr->next) | |
467 | { | |
468 | if (curr->maxshift > curr->parent->maxshift) | |
469 | curr->maxshift = curr->parent->maxshift; | |
470 | if (curr->shift > curr->maxshift) | |
471 | curr->shift = curr->maxshift; | |
472 | } | |
473 | ||
474 | /* Create a vector, indexed by character code, of the outgoing links | |
475 | from the root node. */ | |
476 | for (i = 0; i < NCHAR; ++i) | |
477 | next[i] = NULL; | |
478 | treenext(kwset->trie->links, next); | |
479 | ||
afe8a907 | 480 | if ((trans = kwset->trans)) |
05f3dbba FK |
481 | for (i = 0; i < NCHAR; ++i) |
482 | kwset->next[i] = next[U(trans[i])]; | |
483 | else | |
921d49be | 484 | COPY_ARRAY(kwset->next, next, NCHAR); |
05f3dbba FK |
485 | } |
486 | ||
487 | /* Fix things up for any translation table. */ | |
afe8a907 | 488 | if ((trans = kwset->trans)) |
05f3dbba FK |
489 | for (i = 0; i < NCHAR; ++i) |
490 | kwset->delta[i] = delta[U(trans[i])]; | |
491 | else | |
492 | memcpy(kwset->delta, delta, NCHAR); | |
493 | ||
494 | return NULL; | |
495 | } | |
496 | ||
497 | /* Fast boyer-moore search. */ | |
498 | static size_t | |
499 | bmexec (kwset_t kws, char const *text, size_t size) | |
500 | { | |
501 | struct kwset const *kwset; | |
502 | register unsigned char const *d1; | |
503 | register char const *ep, *sp, *tp; | |
504 | register int d, gc, i, len, md2; | |
505 | ||
506 | kwset = (struct kwset const *) kws; | |
507 | len = kwset->mind; | |
508 | ||
509 | if (len == 0) | |
510 | return 0; | |
511 | if (len > size) | |
512 | return -1; | |
513 | if (len == 1) | |
514 | { | |
515 | tp = memchr (text, kwset->target[0], size); | |
516 | return tp ? tp - text : -1; | |
517 | } | |
518 | ||
519 | d1 = kwset->delta; | |
520 | sp = kwset->target + len; | |
521 | gc = U(sp[-2]); | |
522 | md2 = kwset->mind2; | |
523 | tp = text + len; | |
524 | ||
525 | /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */ | |
526 | if (size > 12 * len) | |
527 | /* 11 is not a bug, the initial offset happens only once. */ | |
528 | for (ep = text + size - 11 * len;;) | |
529 | { | |
530 | while (tp <= ep) | |
531 | { | |
532 | d = d1[U(tp[-1])], tp += d; | |
533 | d = d1[U(tp[-1])], tp += d; | |
534 | if (d == 0) | |
535 | goto found; | |
536 | d = d1[U(tp[-1])], tp += d; | |
537 | d = d1[U(tp[-1])], tp += d; | |
538 | d = d1[U(tp[-1])], tp += d; | |
539 | if (d == 0) | |
540 | goto found; | |
541 | d = d1[U(tp[-1])], tp += d; | |
542 | d = d1[U(tp[-1])], tp += d; | |
543 | d = d1[U(tp[-1])], tp += d; | |
544 | if (d == 0) | |
545 | goto found; | |
546 | d = d1[U(tp[-1])], tp += d; | |
547 | d = d1[U(tp[-1])], tp += d; | |
548 | } | |
549 | break; | |
550 | found: | |
551 | if (U(tp[-2]) == gc) | |
552 | { | |
553 | for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i) | |
554 | ; | |
555 | if (i > len) | |
556 | return tp - len - text; | |
557 | } | |
558 | tp += md2; | |
559 | } | |
560 | ||
561 | /* Now we have only a few characters left to search. We | |
562 | carefully avoid ever producing an out-of-bounds pointer. */ | |
563 | ep = text + size; | |
564 | d = d1[U(tp[-1])]; | |
565 | while (d <= ep - tp) | |
566 | { | |
567 | d = d1[U((tp += d)[-1])]; | |
568 | if (d != 0) | |
569 | continue; | |
570 | if (U(tp[-2]) == gc) | |
571 | { | |
572 | for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i) | |
573 | ; | |
574 | if (i > len) | |
575 | return tp - len - text; | |
576 | } | |
577 | d = md2; | |
578 | } | |
579 | ||
580 | return -1; | |
581 | } | |
582 | ||
583 | /* Hairy multiple string search. */ | |
584 | static size_t | |
585 | cwexec (kwset_t kws, char const *text, size_t len, struct kwsmatch *kwsmatch) | |
586 | { | |
587 | struct kwset const *kwset; | |
588 | struct trie * const *next; | |
589 | struct trie const *trie; | |
590 | struct trie const *accept; | |
591 | char const *beg, *lim, *mch, *lmch; | |
592 | register unsigned char c; | |
593 | register unsigned char const *delta; | |
594 | register int d; | |
595 | register char const *end, *qlim; | |
596 | register struct tree const *tree; | |
189c860c | 597 | register unsigned char const *trans; |
05f3dbba | 598 | |
05f3dbba | 599 | accept = NULL; |
05f3dbba FK |
600 | |
601 | /* Initialize register copies and look for easy ways out. */ | |
602 | kwset = (struct kwset *) kws; | |
603 | if (len < kwset->mind) | |
604 | return -1; | |
605 | next = kwset->next; | |
606 | delta = kwset->delta; | |
607 | trans = kwset->trans; | |
608 | lim = text + len; | |
609 | end = text; | |
610 | if ((d = kwset->mind) != 0) | |
611 | mch = NULL; | |
612 | else | |
613 | { | |
614 | mch = text, accept = kwset->trie; | |
615 | goto match; | |
616 | } | |
617 | ||
618 | if (len >= 4 * kwset->mind) | |
619 | qlim = lim - 4 * kwset->mind; | |
620 | else | |
621 | qlim = NULL; | |
622 | ||
623 | while (lim - end >= d) | |
624 | { | |
625 | if (qlim && end <= qlim) | |
626 | { | |
627 | end += d - 1; | |
628 | while ((d = delta[c = *end]) && end < qlim) | |
629 | { | |
630 | end += d; | |
631 | end += delta[U(*end)]; | |
632 | end += delta[U(*end)]; | |
633 | } | |
634 | ++end; | |
635 | } | |
636 | else | |
637 | d = delta[c = (end += d)[-1]]; | |
638 | if (d) | |
639 | continue; | |
640 | beg = end - 1; | |
641 | trie = next[c]; | |
642 | if (trie->accepting) | |
643 | { | |
644 | mch = beg; | |
645 | accept = trie; | |
646 | } | |
647 | d = trie->shift; | |
648 | while (beg > text) | |
649 | { | |
650 | c = trans ? trans[U(*--beg)] : *--beg; | |
651 | tree = trie->links; | |
652 | while (tree && c != tree->label) | |
653 | if (c < tree->label) | |
654 | tree = tree->llink; | |
655 | else | |
656 | tree = tree->rlink; | |
657 | if (tree) | |
658 | { | |
659 | trie = tree->trie; | |
660 | if (trie->accepting) | |
661 | { | |
662 | mch = beg; | |
663 | accept = trie; | |
664 | } | |
665 | } | |
666 | else | |
667 | break; | |
668 | d = trie->shift; | |
669 | } | |
670 | if (mch) | |
671 | goto match; | |
672 | } | |
673 | return -1; | |
674 | ||
675 | match: | |
676 | /* Given a known match, find the longest possible match anchored | |
677 | at or before its starting point. This is nearly a verbatim | |
678 | copy of the preceding main search loops. */ | |
679 | if (lim - mch > kwset->maxd) | |
680 | lim = mch + kwset->maxd; | |
a946ef55 | 681 | lmch = NULL; |
05f3dbba FK |
682 | d = 1; |
683 | while (lim - end >= d) | |
684 | { | |
685 | if ((d = delta[c = (end += d)[-1]]) != 0) | |
686 | continue; | |
687 | beg = end - 1; | |
688 | if (!(trie = next[c])) | |
689 | { | |
690 | d = 1; | |
691 | continue; | |
692 | } | |
693 | if (trie->accepting && beg <= mch) | |
694 | { | |
695 | lmch = beg; | |
696 | accept = trie; | |
697 | } | |
698 | d = trie->shift; | |
699 | while (beg > text) | |
700 | { | |
701 | c = trans ? trans[U(*--beg)] : *--beg; | |
702 | tree = trie->links; | |
703 | while (tree && c != tree->label) | |
704 | if (c < tree->label) | |
705 | tree = tree->llink; | |
706 | else | |
707 | tree = tree->rlink; | |
708 | if (tree) | |
709 | { | |
710 | trie = tree->trie; | |
711 | if (trie->accepting && beg <= mch) | |
712 | { | |
713 | lmch = beg; | |
714 | accept = trie; | |
715 | } | |
716 | } | |
717 | else | |
718 | break; | |
719 | d = trie->shift; | |
720 | } | |
721 | if (lmch) | |
722 | { | |
723 | mch = lmch; | |
724 | goto match; | |
725 | } | |
726 | if (!d) | |
727 | d = 1; | |
728 | } | |
729 | ||
730 | if (kwsmatch) | |
731 | { | |
732 | kwsmatch->index = accept->accepting / 2; | |
733 | kwsmatch->offset[0] = mch - text; | |
734 | kwsmatch->size[0] = accept->depth; | |
735 | } | |
736 | return mch - text; | |
737 | } | |
738 | ||
739 | /* Search through the given text for a match of any member of the | |
740 | given keyword set. Return a pointer to the first character of | |
741 | the matching substring, or NULL if no match is found. If FOUNDLEN | |
742 | is non-NULL store in the referenced location the length of the | |
743 | matching substring. Similarly, if FOUNDIDX is non-NULL, store | |
744 | in the referenced location the index number of the particular | |
745 | keyword matched. */ | |
746 | size_t | |
747 | kwsexec (kwset_t kws, char const *text, size_t size, | |
748 | struct kwsmatch *kwsmatch) | |
749 | { | |
750 | struct kwset const *kwset = (struct kwset *) kws; | |
751 | if (kwset->words == 1 && kwset->trans == NULL) | |
752 | { | |
753 | size_t ret = bmexec (kws, text, size); | |
754 | if (kwsmatch != NULL && ret != (size_t) -1) | |
755 | { | |
756 | kwsmatch->index = 0; | |
757 | kwsmatch->offset[0] = ret; | |
758 | kwsmatch->size[0] = kwset->mind; | |
759 | } | |
760 | return ret; | |
761 | } | |
762 | else | |
763 | return cwexec(kws, text, size, kwsmatch); | |
764 | } | |
765 | ||
766 | /* Free the components of the given keyword set. */ | |
767 | void | |
768 | kwsfree (kwset_t kws) | |
769 | { | |
770 | struct kwset *kwset; | |
771 | ||
772 | kwset = (struct kwset *) kws; | |
773 | obstack_free(&kwset->obstack, NULL); | |
774 | free(kws); | |
775 | } |