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regc_nfa.c
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1/*
2 * NFA utilities.
3 * This file is #included by regcomp.c.
4 *
5 * Copyright (c) 1998, 1999 Henry Spencer. All rights reserved.
6 *
7 * Development of this software was funded, in part, by Cray Research Inc.,
8 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
9 * Corporation, none of whom are responsible for the results. The author
10 * thanks all of them.
11 *
12 * Redistribution and use in source and binary forms -- with or without
13 * modification -- are permitted for any purpose, provided that
14 * redistributions in source form retain this entire copyright notice and
15 * indicate the origin and nature of any modifications.
16 *
17 * I'd appreciate being given credit for this package in the documentation
18 * of software which uses it, but that is not a requirement.
19 *
20 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
21 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
22 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
23 * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
26 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
28 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
29 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 * src/backend/regex/regc_nfa.c
32 *
33 *
34 * One or two things that technically ought to be in here
35 * are actually in color.c, thanks to some incestuous relationships in
36 * the color chains.
37 */
38
39#define NISERR() VISERR(nfa->v)
40#define NERR(e) VERR(nfa->v, (e))
41
42
43/*
44 * newnfa - set up an NFA
45 */
46static struct nfa * /* the NFA, or NULL */
47newnfa(struct vars *v,
48 struct colormap *cm,
49 struct nfa *parent) /* NULL if primary NFA */
50{
51 struct nfa *nfa;
52
53 nfa = (struct nfa *) MALLOC(sizeof(struct nfa));
54 if (nfa == NULL)
55 {
56 ERR(REG_ESPACE);
57 return NULL;
58 }
59
60 /* Make the NFA minimally valid, so freenfa() will behave sanely */
61 nfa->states = NULL;
62 nfa->slast = NULL;
63 nfa->freestates = NULL;
64 nfa->freearcs = NULL;
65 nfa->lastsb = NULL;
66 nfa->lastab = NULL;
67 nfa->lastsbused = 0;
68 nfa->lastabused = 0;
69 nfa->nstates = 0;
70 nfa->cm = cm;
71 nfa->v = v;
72 nfa->bos[0] = nfa->bos[1] = COLORLESS;
73 nfa->eos[0] = nfa->eos[1] = COLORLESS;
74 nfa->flags = 0;
75 nfa->minmatchall = nfa->maxmatchall = -1;
76 nfa->parent = parent; /* Precedes newfstate so parent is valid. */
77
78 /* Create required infrastructure */
79 nfa->post = newfstate(nfa, '@'); /* number 0 */
80 nfa->pre = newfstate(nfa, '>'); /* number 1 */
81 nfa->init = newstate(nfa); /* may become invalid later */
82 nfa->final = newstate(nfa);
83 if (ISERR())
84 {
85 freenfa(nfa);
86 return NULL;
87 }
88 rainbow(nfa, nfa->cm, PLAIN, COLORLESS, nfa->pre, nfa->init);
89 newarc(nfa, '^', 1, nfa->pre, nfa->init);
90 newarc(nfa, '^', 0, nfa->pre, nfa->init);
91 rainbow(nfa, nfa->cm, PLAIN, COLORLESS, nfa->final, nfa->post);
92 newarc(nfa, '$', 1, nfa->final, nfa->post);
93 newarc(nfa, '$', 0, nfa->final, nfa->post);
94
95 if (ISERR())
96 {
97 freenfa(nfa);
98 return NULL;
99 }
100 return nfa;
101}
102
103/*
104 * freenfa - free an entire NFA
105 */
106static void
107freenfa(struct nfa *nfa)
108{
109 struct statebatch *sb;
110 struct statebatch *sbnext;
111 struct arcbatch *ab;
112 struct arcbatch *abnext;
113
114 for (sb = nfa->lastsb; sb != NULL; sb = sbnext)
115 {
116 sbnext = sb->next;
117 nfa->v->spaceused -= STATEBATCHSIZE(sb->nstates);
118 FREE(sb);
119 }
120 nfa->lastsb = NULL;
121 for (ab = nfa->lastab; ab != NULL; ab = abnext)
122 {
123 abnext = ab->next;
124 nfa->v->spaceused -= ARCBATCHSIZE(ab->narcs);
125 FREE(ab);
126 }
127 nfa->lastab = NULL;
128
129 nfa->nstates = -1;
130 FREE(nfa);
131}
132
133/*
134 * newstate - allocate an NFA state, with zero flag value
135 */
136static struct state * /* NULL on error */
137newstate(struct nfa *nfa)
138{
139 struct state *s;
140
141 /*
142 * This is a handy place to check for operation cancel during regex
143 * compilation, since no code path will go very long without making a new
144 * state or arc.
145 */
146 INTERRUPT(nfa->v->re);
147
148 /* first, recycle anything that's on the freelist */
149 if (nfa->freestates != NULL)
150 {
151 s = nfa->freestates;
152 nfa->freestates = s->next;
153 }
154 /* otherwise, is there anything left in the last statebatch? */
155 else if (nfa->lastsb != NULL && nfa->lastsbused < nfa->lastsb->nstates)
156 {
157 s = &nfa->lastsb->s[nfa->lastsbused++];
158 }
159 /* otherwise, need to allocate a new statebatch */
160 else
161 {
162 struct statebatch *newSb;
163 size_t nstates;
164
165 if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE)
166 {
167 NERR(REG_ETOOBIG);
168 return NULL;
169 }
170 nstates = (nfa->lastsb != NULL) ? nfa->lastsb->nstates * 2 : FIRSTSBSIZE;
171 if (nstates > MAXSBSIZE)
172 nstates = MAXSBSIZE;
173 newSb = (struct statebatch *) MALLOC(STATEBATCHSIZE(nstates));
174 if (newSb == NULL)
175 {
176 NERR(REG_ESPACE);
177 return NULL;
178 }
179 nfa->v->spaceused += STATEBATCHSIZE(nstates);
180 newSb->nstates = nstates;
181 newSb->next = nfa->lastsb;
182 nfa->lastsb = newSb;
183 nfa->lastsbused = 1;
184 s = &newSb->s[0];
185 }
186
187 assert(nfa->nstates >= 0);
188 s->no = nfa->nstates++;
189 s->flag = 0;
190 if (nfa->states == NULL)
191 nfa->states = s;
192 s->nins = 0;
193 s->ins = NULL;
194 s->nouts = 0;
195 s->outs = NULL;
196 s->tmp = NULL;
197 s->next = NULL;
198 if (nfa->slast != NULL)
199 {
200 assert(nfa->slast->next == NULL);
201 nfa->slast->next = s;
202 }
203 s->prev = nfa->slast;
204 nfa->slast = s;
205 return s;
206}
207
208/*
209 * newfstate - allocate an NFA state with a specified flag value
210 */
211static struct state * /* NULL on error */
212newfstate(struct nfa *nfa, int flag)
213{
214 struct state *s;
215
216 s = newstate(nfa);
217 if (s != NULL)
218 s->flag = (char) flag;
219 return s;
220}
221
222/*
223 * dropstate - delete a state's inarcs and outarcs and free it
224 */
225static void
226dropstate(struct nfa *nfa,
227 struct state *s)
228{
229 struct arc *a;
230
231 while ((a = s->ins) != NULL)
232 freearc(nfa, a);
233 while ((a = s->outs) != NULL)
234 freearc(nfa, a);
235 freestate(nfa, s);
236}
237
238/*
239 * freestate - free a state, which has no in-arcs or out-arcs
240 */
241static void
242freestate(struct nfa *nfa,
243 struct state *s)
244{
245 assert(s != NULL);
246 assert(s->nins == 0 && s->nouts == 0);
247
248 s->no = FREESTATE;
249 s->flag = 0;
250 if (s->next != NULL)
251 s->next->prev = s->prev;
252 else
253 {
254 assert(s == nfa->slast);
255 nfa->slast = s->prev;
256 }
257 if (s->prev != NULL)
258 s->prev->next = s->next;
259 else
260 {
261 assert(s == nfa->states);
262 nfa->states = s->next;
263 }
264 s->prev = NULL;
265 s->next = nfa->freestates; /* don't delete it, put it on the free list */
266 nfa->freestates = s;
267}
268
269/*
270 * newarc - set up a new arc within an NFA
271 *
272 * This function checks to make sure that no duplicate arcs are created.
273 * In general we never want duplicates.
274 *
275 * However: in principle, a RAINBOW arc is redundant with any plain arc
276 * (unless that arc is for a pseudocolor). But we don't try to recognize
277 * that redundancy, either here or in allied operations such as moveins().
278 * The pseudocolor consideration makes that more costly than it seems worth.
279 */
280static void
281newarc(struct nfa *nfa,
282 int t,
283 color co,
284 struct state *from,
285 struct state *to)
286{
287 struct arc *a;
288
289 assert(from != NULL && to != NULL);
290
291 /*
292 * This is a handy place to check for operation cancel during regex
293 * compilation, since no code path will go very long without making a new
294 * state or arc.
295 */
296 INTERRUPT(nfa->v->re);
297
298 /* check for duplicate arc, using whichever chain is shorter */
299 if (from->nouts <= to->nins)
300 {
301 for (a = from->outs; a != NULL; a = a->outchain)
302 if (a->to == to && a->co == co && a->type == t)
303 return;
304 }
305 else
306 {
307 for (a = to->ins; a != NULL; a = a->inchain)
308 if (a->from == from && a->co == co && a->type == t)
309 return;
310 }
311
312 /* no dup, so create the arc */
313 createarc(nfa, t, co, from, to);
314}
315
316/*
317 * createarc - create a new arc within an NFA
318 *
319 * This function must *only* be used after verifying that there is no existing
320 * identical arc (same type/color/from/to).
321 */
322static void
323createarc(struct nfa *nfa,
324 int t,
325 color co,
326 struct state *from,
327 struct state *to)
328{
329 struct arc *a;
330
331 a = allocarc(nfa);
332 if (NISERR())
333 return;
334 assert(a != NULL);
335
336 a->type = t;
337 a->co = co;
338 a->to = to;
339 a->from = from;
340
341 /*
342 * Put the new arc on the beginning, not the end, of the chains; it's
343 * simpler here, and freearc() is the same cost either way. See also the
344 * logic in moveins() and its cohorts, as well as fixempties().
345 */
346 a->inchain = to->ins;
347 a->inchainRev = NULL;
348 if (to->ins)
349 to->ins->inchainRev = a;
350 to->ins = a;
351 a->outchain = from->outs;
352 a->outchainRev = NULL;
353 if (from->outs)
354 from->outs->outchainRev = a;
355 from->outs = a;
356
357 from->nouts++;
358 to->nins++;
359
360 if (COLORED(a) && nfa->parent == NULL)
361 colorchain(nfa->cm, a);
362}
363
364/*
365 * allocarc - allocate a new arc within an NFA
366 */
367static struct arc * /* NULL for failure */
368allocarc(struct nfa *nfa)
369{
370 struct arc *a;
371
372 /* first, recycle anything that's on the freelist */
373 if (nfa->freearcs != NULL)
374 {
375 a = nfa->freearcs;
376 nfa->freearcs = a->freechain;
377 }
378 /* otherwise, is there anything left in the last arcbatch? */
379 else if (nfa->lastab != NULL && nfa->lastabused < nfa->lastab->narcs)
380 {
381 a = &nfa->lastab->a[nfa->lastabused++];
382 }
383 /* otherwise, need to allocate a new arcbatch */
384 else
385 {
386 struct arcbatch *newAb;
387 size_t narcs;
388
389 if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE)
390 {
391 NERR(REG_ETOOBIG);
392 return NULL;
393 }
394 narcs = (nfa->lastab != NULL) ? nfa->lastab->narcs * 2 : FIRSTABSIZE;
395 if (narcs > MAXABSIZE)
396 narcs = MAXABSIZE;
397 newAb = (struct arcbatch *) MALLOC(ARCBATCHSIZE(narcs));
398 if (newAb == NULL)
399 {
400 NERR(REG_ESPACE);
401 return NULL;
402 }
403 nfa->v->spaceused += ARCBATCHSIZE(narcs);
404 newAb->narcs = narcs;
405 newAb->next = nfa->lastab;
406 nfa->lastab = newAb;
407 nfa->lastabused = 1;
408 a = &newAb->a[0];
409 }
410
411 return a;
412}
413
414/*
415 * freearc - free an arc
416 */
417static void
418freearc(struct nfa *nfa,
419 struct arc *victim)
420{
421 struct state *from = victim->from;
422 struct state *to = victim->to;
423 struct arc *predecessor;
424
425 assert(victim->type != 0);
426
427 /* take it off color chain if necessary */
428 if (COLORED(victim) && nfa->parent == NULL)
429 uncolorchain(nfa->cm, victim);
430
431 /* take it off source's out-chain */
432 assert(from != NULL);
433 predecessor = victim->outchainRev;
434 if (predecessor == NULL)
435 {
436 assert(from->outs == victim);
437 from->outs = victim->outchain;
438 }
439 else
440 {
441 assert(predecessor->outchain == victim);
442 predecessor->outchain = victim->outchain;
443 }
444 if (victim->outchain != NULL)
445 {
446 assert(victim->outchain->outchainRev == victim);
447 victim->outchain->outchainRev = predecessor;
448 }
449 from->nouts--;
450
451 /* take it off target's in-chain */
452 assert(to != NULL);
453 predecessor = victim->inchainRev;
454 if (predecessor == NULL)
455 {
456 assert(to->ins == victim);
457 to->ins = victim->inchain;
458 }
459 else
460 {
461 assert(predecessor->inchain == victim);
462 predecessor->inchain = victim->inchain;
463 }
464 if (victim->inchain != NULL)
465 {
466 assert(victim->inchain->inchainRev == victim);
467 victim->inchain->inchainRev = predecessor;
468 }
469 to->nins--;
470
471 /* clean up and place on NFA's free list */
472 victim->type = 0;
473 victim->from = NULL; /* precautions... */
474 victim->to = NULL;
475 victim->inchain = NULL;
476 victim->inchainRev = NULL;
477 victim->outchain = NULL;
478 victim->outchainRev = NULL;
479 victim->freechain = nfa->freearcs;
480 nfa->freearcs = victim;
481}
482
483/*
484 * changearcsource - flip an arc to have a different from state
485 *
486 * Caller must have verified that there is no pre-existing duplicate arc.
487 */
488static void
489changearcsource(struct arc *a, struct state *newfrom)
490{
491 struct state *oldfrom = a->from;
492 struct arc *predecessor;
493
494 assert(oldfrom != newfrom);
495
496 /* take it off old source's out-chain */
497 assert(oldfrom != NULL);
498 predecessor = a->outchainRev;
499 if (predecessor == NULL)
500 {
501 assert(oldfrom->outs == a);
502 oldfrom->outs = a->outchain;
503 }
504 else
505 {
506 assert(predecessor->outchain == a);
507 predecessor->outchain = a->outchain;
508 }
509 if (a->outchain != NULL)
510 {
511 assert(a->outchain->outchainRev == a);
512 a->outchain->outchainRev = predecessor;
513 }
514 oldfrom->nouts--;
515
516 a->from = newfrom;
517
518 /* prepend it to new source's out-chain */
519 a->outchain = newfrom->outs;
520 a->outchainRev = NULL;
521 if (newfrom->outs)
522 newfrom->outs->outchainRev = a;
523 newfrom->outs = a;
524 newfrom->nouts++;
525}
526
527/*
528 * changearctarget - flip an arc to have a different to state
529 *
530 * Caller must have verified that there is no pre-existing duplicate arc.
531 */
532static void
533changearctarget(struct arc *a, struct state *newto)
534{
535 struct state *oldto = a->to;
536 struct arc *predecessor;
537
538 assert(oldto != newto);
539
540 /* take it off old target's in-chain */
541 assert(oldto != NULL);
542 predecessor = a->inchainRev;
543 if (predecessor == NULL)
544 {
545 assert(oldto->ins == a);
546 oldto->ins = a->inchain;
547 }
548 else
549 {
550 assert(predecessor->inchain == a);
551 predecessor->inchain = a->inchain;
552 }
553 if (a->inchain != NULL)
554 {
555 assert(a->inchain->inchainRev == a);
556 a->inchain->inchainRev = predecessor;
557 }
558 oldto->nins--;
559
560 a->to = newto;
561
562 /* prepend it to new target's in-chain */
563 a->inchain = newto->ins;
564 a->inchainRev = NULL;
565 if (newto->ins)
566 newto->ins->inchainRev = a;
567 newto->ins = a;
568 newto->nins++;
569}
570
571/*
572 * hasnonemptyout - Does state have a non-EMPTY out arc?
573 */
574static int
575hasnonemptyout(struct state *s)
576{
577 struct arc *a;
578
579 for (a = s->outs; a != NULL; a = a->outchain)
580 {
581 if (a->type != EMPTY)
582 return 1;
583 }
584 return 0;
585}
586
587/*
588 * findarc - find arc, if any, from given source with given type and color
589 * If there is more than one such arc, the result is random.
590 */
591static struct arc *
592findarc(struct state *s,
593 int type,
594 color co)
595{
596 struct arc *a;
597
598 for (a = s->outs; a != NULL; a = a->outchain)
599 if (a->type == type && a->co == co)
600 return a;
601 return NULL;
602}
603
604/*
605 * cparc - allocate a new arc within an NFA, copying details from old one
606 */
607static void
608cparc(struct nfa *nfa,
609 struct arc *oa,
610 struct state *from,
611 struct state *to)
612{
613 newarc(nfa, oa->type, oa->co, from, to);
614}
615
616/*
617 * sortins - sort the in arcs of a state by from/color/type
618 */
619static void
620sortins(struct nfa *nfa,
621 struct state *s)
622{
623 struct arc **sortarray;
624 struct arc *a;
625 int n = s->nins;
626 int i;
627
628 if (n <= 1)
629 return; /* nothing to do */
630 /* make an array of arc pointers ... */
631 sortarray = (struct arc **) MALLOC(n * sizeof(struct arc *));
632 if (sortarray == NULL)
633 {
634 NERR(REG_ESPACE);
635 return;
636 }
637 i = 0;
638 for (a = s->ins; a != NULL; a = a->inchain)
639 sortarray[i++] = a;
640 assert(i == n);
641 /* ... sort the array */
642 qsort(sortarray, n, sizeof(struct arc *), sortins_cmp);
643 /* ... and rebuild arc list in order */
644 /* it seems worth special-casing first and last items to simplify loop */
645 a = sortarray[0];
646 s->ins = a;
647 a->inchain = sortarray[1];
648 a->inchainRev = NULL;
649 for (i = 1; i < n - 1; i++)
650 {
651 a = sortarray[i];
652 a->inchain = sortarray[i + 1];
653 a->inchainRev = sortarray[i - 1];
654 }
655 a = sortarray[i];
656 a->inchain = NULL;
657 a->inchainRev = sortarray[i - 1];
658 FREE(sortarray);
659}
660
661static int
662sortins_cmp(const void *a, const void *b)
663{
664 const struct arc *aa = *((const struct arc *const *) a);
665 const struct arc *bb = *((const struct arc *const *) b);
666
667 /* we check the fields in the order they are most likely to be different */
668 if (aa->from->no < bb->from->no)
669 return -1;
670 if (aa->from->no > bb->from->no)
671 return 1;
672 if (aa->co < bb->co)
673 return -1;
674 if (aa->co > bb->co)
675 return 1;
676 if (aa->type < bb->type)
677 return -1;
678 if (aa->type > bb->type)
679 return 1;
680 return 0;
681}
682
683/*
684 * sortouts - sort the out arcs of a state by to/color/type
685 */
686static void
687sortouts(struct nfa *nfa,
688 struct state *s)
689{
690 struct arc **sortarray;
691 struct arc *a;
692 int n = s->nouts;
693 int i;
694
695 if (n <= 1)
696 return; /* nothing to do */
697 /* make an array of arc pointers ... */
698 sortarray = (struct arc **) MALLOC(n * sizeof(struct arc *));
699 if (sortarray == NULL)
700 {
701 NERR(REG_ESPACE);
702 return;
703 }
704 i = 0;
705 for (a = s->outs; a != NULL; a = a->outchain)
706 sortarray[i++] = a;
707 assert(i == n);
708 /* ... sort the array */
709 qsort(sortarray, n, sizeof(struct arc *), sortouts_cmp);
710 /* ... and rebuild arc list in order */
711 /* it seems worth special-casing first and last items to simplify loop */
712 a = sortarray[0];
713 s->outs = a;
714 a->outchain = sortarray[1];
715 a->outchainRev = NULL;
716 for (i = 1; i < n - 1; i++)
717 {
718 a = sortarray[i];
719 a->outchain = sortarray[i + 1];
720 a->outchainRev = sortarray[i - 1];
721 }
722 a = sortarray[i];
723 a->outchain = NULL;
724 a->outchainRev = sortarray[i - 1];
725 FREE(sortarray);
726}
727
728static int
729sortouts_cmp(const void *a, const void *b)
730{
731 const struct arc *aa = *((const struct arc *const *) a);
732 const struct arc *bb = *((const struct arc *const *) b);
733
734 /* we check the fields in the order they are most likely to be different */
735 if (aa->to->no < bb->to->no)
736 return -1;
737 if (aa->to->no > bb->to->no)
738 return 1;
739 if (aa->co < bb->co)
740 return -1;
741 if (aa->co > bb->co)
742 return 1;
743 if (aa->type < bb->type)
744 return -1;
745 if (aa->type > bb->type)
746 return 1;
747 return 0;
748}
749
750/*
751 * Common decision logic about whether to use arc-by-arc operations or
752 * sort/merge. If there's just a few source arcs we cannot recoup the
753 * cost of sorting the destination arc list, no matter how large it is.
754 * Otherwise, limit the number of arc-by-arc comparisons to about 1000
755 * (a somewhat arbitrary choice, but the breakeven point would probably
756 * be machine dependent anyway).
757 */
758#define BULK_ARC_OP_USE_SORT(nsrcarcs, ndestarcs) \
759 ((nsrcarcs) < 4 ? 0 : ((nsrcarcs) > 32 || (ndestarcs) > 32))
760
761/*
762 * moveins - move all in arcs of a state to another state
763 *
764 * You might think this could be done better by just updating the
765 * existing arcs, and you would be right if it weren't for the need
766 * for duplicate suppression, which makes it easier to just make new
767 * ones to exploit the suppression built into newarc.
768 *
769 * However, if we have a whole lot of arcs to deal with, retail duplicate
770 * checks become too slow. In that case we proceed by sorting and merging
771 * the arc lists, and then we can indeed just update the arcs in-place.
772 *
773 * On the other hand, it's also true that this is frequently called with
774 * a brand-new newState that has no existing in-arcs. In that case,
775 * de-duplication is unnecessary, so we can just blindly move all the arcs.
776 */
777static void
778moveins(struct nfa *nfa,
779 struct state *oldState,
780 struct state *newState)
781{
782 assert(oldState != newState);
783
784 if (newState->nins == 0)
785 {
786 /* No need for de-duplication */
787 struct arc *a;
788
789 while ((a = oldState->ins) != NULL)
790 {
791 createarc(nfa, a->type, a->co, a->from, newState);
792 freearc(nfa, a);
793 }
794 }
795 else if (!BULK_ARC_OP_USE_SORT(oldState->nins, newState->nins))
796 {
797 /* With not too many arcs, just do them one at a time */
798 struct arc *a;
799
800 while ((a = oldState->ins) != NULL)
801 {
802 cparc(nfa, a, a->from, newState);
803 freearc(nfa, a);
804 }
805 }
806 else
807 {
808 /*
809 * With many arcs, use a sort-merge approach. Note changearctarget()
810 * will put the arc onto the front of newState's chain, so it does not
811 * break our walk through the sorted part of the chain.
812 */
813 struct arc *oa;
814 struct arc *na;
815
816 /*
817 * Because we bypass newarc() in this code path, we'd better include a
818 * cancel check.
819 */
820 INTERRUPT(nfa->v->re);
821
822 sortins(nfa, oldState);
823 sortins(nfa, newState);
824 if (NISERR())
825 return; /* might have failed to sort */
826 oa = oldState->ins;
827 na = newState->ins;
828 while (oa != NULL && na != NULL)
829 {
830 struct arc *a = oa;
831
832 switch (sortins_cmp(&oa, &na))
833 {
834 case -1:
835 /* newState does not have anything matching oa */
836 oa = oa->inchain;
837
838 /*
839 * Rather than doing createarc+freearc, we can just unlink
840 * and relink the existing arc struct.
841 */
842 changearctarget(a, newState);
843 break;
844 case 0:
845 /* match, advance in both lists */
846 oa = oa->inchain;
847 na = na->inchain;
848 /* ... and drop duplicate arc from oldState */
849 freearc(nfa, a);
850 break;
851 case +1:
852 /* advance only na; oa might have a match later */
853 na = na->inchain;
854 break;
855 default:
856 assert(NOTREACHED);
857 }
858 }
859 while (oa != NULL)
860 {
861 /* newState does not have anything matching oa */
862 struct arc *a = oa;
863
864 oa = oa->inchain;
865 changearctarget(a, newState);
866 }
867 }
868
869 assert(oldState->nins == 0);
870 assert(oldState->ins == NULL);
871}
872
873/*
874 * copyins - copy in arcs of a state to another state
875 *
876 * The comments for moveins() apply here as well. However, in current
877 * usage, this is *only* called with brand-new target states, so that
878 * only the "no need for de-duplication" code path is ever reached.
879 * We keep the rest #ifdef'd out in case it's needed in the future.
880 */
881static void
882copyins(struct nfa *nfa,
883 struct state *oldState,
884 struct state *newState)
885{
886 assert(oldState != newState);
887 assert(newState->nins == 0); /* see comment above */
888
889 if (newState->nins == 0)
890 {
891 /* No need for de-duplication */
892 struct arc *a;
893
894 for (a = oldState->ins; a != NULL; a = a->inchain)
895 createarc(nfa, a->type, a->co, a->from, newState);
896 }
897#ifdef NOT_USED /* see comment above */
898 else if (!BULK_ARC_OP_USE_SORT(oldState->nins, newState->nins))
899 {
900 /* With not too many arcs, just do them one at a time */
901 struct arc *a;
902
903 for (a = oldState->ins; a != NULL; a = a->inchain)
904 cparc(nfa, a, a->from, newState);
905 }
906 else
907 {
908 /*
909 * With many arcs, use a sort-merge approach. Note that createarc()
910 * will put new arcs onto the front of newState's chain, so it does
911 * not break our walk through the sorted part of the chain.
912 */
913 struct arc *oa;
914 struct arc *na;
915
916 /*
917 * Because we bypass newarc() in this code path, we'd better include a
918 * cancel check.
919 */
920 INTERRUPT(nfa->v->re);
921
922 sortins(nfa, oldState);
923 sortins(nfa, newState);
924 if (NISERR())
925 return; /* might have failed to sort */
926 oa = oldState->ins;
927 na = newState->ins;
928 while (oa != NULL && na != NULL)
929 {
930 struct arc *a = oa;
931
932 switch (sortins_cmp(&oa, &na))
933 {
934 case -1:
935 /* newState does not have anything matching oa */
936 oa = oa->inchain;
937 createarc(nfa, a->type, a->co, a->from, newState);
938 break;
939 case 0:
940 /* match, advance in both lists */
941 oa = oa->inchain;
942 na = na->inchain;
943 break;
944 case +1:
945 /* advance only na; oa might have a match later */
946 na = na->inchain;
947 break;
948 default:
949 assert(NOTREACHED);
950 }
951 }
952 while (oa != NULL)
953 {
954 /* newState does not have anything matching oa */
955 struct arc *a = oa;
956
957 oa = oa->inchain;
958 createarc(nfa, a->type, a->co, a->from, newState);
959 }
960 }
961#endif /* NOT_USED */
962}
963
964/*
965 * mergeins - merge a list of inarcs into a state
966 *
967 * This is much like copyins, but the source arcs are listed in an array,
968 * and are not guaranteed unique. It's okay to clobber the array contents.
969 */
970static void
971mergeins(struct nfa *nfa,
972 struct state *s,
973 struct arc **arcarray,
974 int arccount)
975{
976 struct arc *na;
977 int i;
978 int j;
979
980 if (arccount <= 0)
981 return;
982
983 /*
984 * Because we bypass newarc() in this code path, we'd better include a
985 * cancel check.
986 */
987 INTERRUPT(nfa->v->re);
988
989 /* Sort existing inarcs as well as proposed new ones */
990 sortins(nfa, s);
991 if (NISERR())
992 return; /* might have failed to sort */
993
994 qsort(arcarray, arccount, sizeof(struct arc *), sortins_cmp);
995
996 /*
997 * arcarray very likely includes dups, so we must eliminate them. (This
998 * could be folded into the next loop, but it's not worth the trouble.)
999 */
1000 j = 0;
1001 for (i = 1; i < arccount; i++)
1002 {
1003 switch (sortins_cmp(&arcarray[j], &arcarray[i]))
1004 {
1005 case -1:
1006 /* non-dup */
1007 arcarray[++j] = arcarray[i];
1008 break;
1009 case 0:
1010 /* dup */
1011 break;
1012 default:
1013 /* trouble */
1014 assert(NOTREACHED);
1015 }
1016 }
1017 arccount = j + 1;
1018
1019 /*
1020 * Now merge into s' inchain. Note that createarc() will put new arcs
1021 * onto the front of s's chain, so it does not break our walk through the
1022 * sorted part of the chain.
1023 */
1024 i = 0;
1025 na = s->ins;
1026 while (i < arccount && na != NULL)
1027 {
1028 struct arc *a = arcarray[i];
1029
1030 switch (sortins_cmp(&a, &na))
1031 {
1032 case -1:
1033 /* s does not have anything matching a */
1034 createarc(nfa, a->type, a->co, a->from, s);
1035 i++;
1036 break;
1037 case 0:
1038 /* match, advance in both lists */
1039 i++;
1040 na = na->inchain;
1041 break;
1042 case +1:
1043 /* advance only na; array might have a match later */
1044 na = na->inchain;
1045 break;
1046 default:
1047 assert(NOTREACHED);
1048 }
1049 }
1050 while (i < arccount)
1051 {
1052 /* s does not have anything matching a */
1053 struct arc *a = arcarray[i];
1054
1055 createarc(nfa, a->type, a->co, a->from, s);
1056 i++;
1057 }
1058}
1059
1060/*
1061 * moveouts - move all out arcs of a state to another state
1062 *
1063 * See comments for moveins()
1064 */
1065static void
1066moveouts(struct nfa *nfa,
1067 struct state *oldState,
1068 struct state *newState)
1069{
1070 assert(oldState != newState);
1071
1072 if (newState->nouts == 0)
1073 {
1074 /* No need for de-duplication */
1075 struct arc *a;
1076
1077 while ((a = oldState->outs) != NULL)
1078 {
1079 createarc(nfa, a->type, a->co, newState, a->to);
1080 freearc(nfa, a);
1081 }
1082 }
1083 else if (!BULK_ARC_OP_USE_SORT(oldState->nouts, newState->nouts))
1084 {
1085 /* With not too many arcs, just do them one at a time */
1086 struct arc *a;
1087
1088 while ((a = oldState->outs) != NULL)
1089 {
1090 cparc(nfa, a, newState, a->to);
1091 freearc(nfa, a);
1092 }
1093 }
1094 else
1095 {
1096 /*
1097 * With many arcs, use a sort-merge approach. Note changearcsource()
1098 * will put the arc onto the front of newState's chain, so it does not
1099 * break our walk through the sorted part of the chain.
1100 */
1101 struct arc *oa;
1102 struct arc *na;
1103
1104 /*
1105 * Because we bypass newarc() in this code path, we'd better include a
1106 * cancel check.
1107 */
1108 INTERRUPT(nfa->v->re);
1109
1110 sortouts(nfa, oldState);
1111 sortouts(nfa, newState);
1112 if (NISERR())
1113 return; /* might have failed to sort */
1114 oa = oldState->outs;
1115 na = newState->outs;
1116 while (oa != NULL && na != NULL)
1117 {
1118 struct arc *a = oa;
1119
1120 switch (sortouts_cmp(&oa, &na))
1121 {
1122 case -1:
1123 /* newState does not have anything matching oa */
1124 oa = oa->outchain;
1125
1126 /*
1127 * Rather than doing createarc+freearc, we can just unlink
1128 * and relink the existing arc struct.
1129 */
1130 changearcsource(a, newState);
1131 break;
1132 case 0:
1133 /* match, advance in both lists */
1134 oa = oa->outchain;
1135 na = na->outchain;
1136 /* ... and drop duplicate arc from oldState */
1137 freearc(nfa, a);
1138 break;
1139 case +1:
1140 /* advance only na; oa might have a match later */
1141 na = na->outchain;
1142 break;
1143 default:
1144 assert(NOTREACHED);
1145 }
1146 }
1147 while (oa != NULL)
1148 {
1149 /* newState does not have anything matching oa */
1150 struct arc *a = oa;
1151
1152 oa = oa->outchain;
1153 changearcsource(a, newState);
1154 }
1155 }
1156
1157 assert(oldState->nouts == 0);
1158 assert(oldState->outs == NULL);
1159}
1160
1161/*
1162 * copyouts - copy out arcs of a state to another state
1163 *
1164 * See comments for copyins()
1165 */
1166static void
1167copyouts(struct nfa *nfa,
1168 struct state *oldState,
1169 struct state *newState)
1170{
1171 assert(oldState != newState);
1172 assert(newState->nouts == 0); /* see comment above */
1173
1174 if (newState->nouts == 0)
1175 {
1176 /* No need for de-duplication */
1177 struct arc *a;
1178
1179 for (a = oldState->outs; a != NULL; a = a->outchain)
1180 createarc(nfa, a->type, a->co, newState, a->to);
1181 }
1182#ifdef NOT_USED /* see comment above */
1183 else if (!BULK_ARC_OP_USE_SORT(oldState->nouts, newState->nouts))
1184 {
1185 /* With not too many arcs, just do them one at a time */
1186 struct arc *a;
1187
1188 for (a = oldState->outs; a != NULL; a = a->outchain)
1189 cparc(nfa, a, newState, a->to);
1190 }
1191 else
1192 {
1193 /*
1194 * With many arcs, use a sort-merge approach. Note that createarc()
1195 * will put new arcs onto the front of newState's chain, so it does
1196 * not break our walk through the sorted part of the chain.
1197 */
1198 struct arc *oa;
1199 struct arc *na;
1200
1201 /*
1202 * Because we bypass newarc() in this code path, we'd better include a
1203 * cancel check.
1204 */
1205 INTERRUPT(nfa->v->re);
1206
1207 sortouts(nfa, oldState);
1208 sortouts(nfa, newState);
1209 if (NISERR())
1210 return; /* might have failed to sort */
1211 oa = oldState->outs;
1212 na = newState->outs;
1213 while (oa != NULL && na != NULL)
1214 {
1215 struct arc *a = oa;
1216
1217 switch (sortouts_cmp(&oa, &na))
1218 {
1219 case -1:
1220 /* newState does not have anything matching oa */
1221 oa = oa->outchain;
1222 createarc(nfa, a->type, a->co, newState, a->to);
1223 break;
1224 case 0:
1225 /* match, advance in both lists */
1226 oa = oa->outchain;
1227 na = na->outchain;
1228 break;
1229 case +1:
1230 /* advance only na; oa might have a match later */
1231 na = na->outchain;
1232 break;
1233 default:
1234 assert(NOTREACHED);
1235 }
1236 }
1237 while (oa != NULL)
1238 {
1239 /* newState does not have anything matching oa */
1240 struct arc *a = oa;
1241
1242 oa = oa->outchain;
1243 createarc(nfa, a->type, a->co, newState, a->to);
1244 }
1245 }
1246#endif /* NOT_USED */
1247}
1248
1249/*
1250 * cloneouts - copy out arcs of a state to another state pair, modifying type
1251 *
1252 * This is only used to convert PLAIN arcs to AHEAD/BEHIND arcs, which share
1253 * the same interpretation of "co". It wouldn't be sensible with LACONs.
1254 */
1255static void
1256cloneouts(struct nfa *nfa,
1257 struct state *old,
1258 struct state *from,
1259 struct state *to,
1260 int type)
1261{
1262 struct arc *a;
1263
1264 assert(old != from);
1265 assert(type == AHEAD || type == BEHIND);
1266
1267 for (a = old->outs; a != NULL; a = a->outchain)
1268 {
1269 assert(a->type == PLAIN);
1270 newarc(nfa, type, a->co, from, to);
1271 }
1272}
1273
1274/*
1275 * delsub - delete a sub-NFA, updating subre pointers if necessary
1276 *
1277 * This uses a recursive traversal of the sub-NFA, marking already-seen
1278 * states using their tmp pointer.
1279 */
1280static void
1281delsub(struct nfa *nfa,
1282 struct state *lp, /* the sub-NFA goes from here... */
1283 struct state *rp) /* ...to here, *not* inclusive */
1284{
1285 assert(lp != rp);
1286
1287 rp->tmp = rp; /* mark end */
1288
1289 deltraverse(nfa, lp, lp);
1290 if (NISERR())
1291 return; /* asserts might not hold after failure */
1292 assert(lp->nouts == 0 && rp->nins == 0); /* did the job */
1293 assert(lp->no != FREESTATE && rp->no != FREESTATE); /* no more */
1294
1295 rp->tmp = NULL; /* unmark end */
1296 lp->tmp = NULL; /* and begin, marked by deltraverse */
1297}
1298
1299/*
1300 * deltraverse - the recursive heart of delsub
1301 * This routine's basic job is to destroy all out-arcs of the state.
1302 */
1303static void
1304deltraverse(struct nfa *nfa,
1305 struct state *leftend,
1306 struct state *s)
1307{
1308 struct arc *a;
1309 struct state *to;
1310
1311 /* Since this is recursive, it could be driven to stack overflow */
1312 if (STACK_TOO_DEEP(nfa->v->re))
1313 {
1314 NERR(REG_ETOOBIG);
1315 return;
1316 }
1317
1318 if (s->nouts == 0)
1319 return; /* nothing to do */
1320 if (s->tmp != NULL)
1321 return; /* already in progress */
1322
1323 s->tmp = s; /* mark as in progress */
1324
1325 while ((a = s->outs) != NULL)
1326 {
1327 to = a->to;
1328 deltraverse(nfa, leftend, to);
1329 if (NISERR())
1330 return; /* asserts might not hold after failure */
1331 assert(to->nouts == 0 || to->tmp != NULL);
1332 freearc(nfa, a);
1333 if (to->nins == 0 && to->tmp == NULL)
1334 {
1335 assert(to->nouts == 0);
1336 freestate(nfa, to);
1337 }
1338 }
1339
1340 assert(s->no != FREESTATE); /* we're still here */
1341 assert(s == leftend || s->nins != 0); /* and still reachable */
1342 assert(s->nouts == 0); /* but have no outarcs */
1343
1344 s->tmp = NULL; /* we're done here */
1345}
1346
1347/*
1348 * dupnfa - duplicate sub-NFA
1349 *
1350 * Another recursive traversal, this time using tmp to point to duplicates
1351 * as well as mark already-seen states. (You knew there was a reason why
1352 * it's a state pointer, didn't you? :-))
1353 */
1354static void
1355dupnfa(struct nfa *nfa,
1356 struct state *start, /* duplicate of subNFA starting here */
1357 struct state *stop, /* and stopping here */
1358 struct state *from, /* stringing duplicate from here */
1359 struct state *to) /* to here */
1360{
1361 if (start == stop)
1362 {
1363 newarc(nfa, EMPTY, 0, from, to);
1364 return;
1365 }
1366
1367 stop->tmp = to;
1368 duptraverse(nfa, start, from);
1369 /* done, except for clearing out the tmp pointers */
1370
1371 stop->tmp = NULL;
1372 cleartraverse(nfa, start);
1373}
1374
1375/*
1376 * duptraverse - recursive heart of dupnfa
1377 */
1378static void
1379duptraverse(struct nfa *nfa,
1380 struct state *s,
1381 struct state *stmp) /* s's duplicate, or NULL */
1382{
1383 struct arc *a;
1384
1385 /* Since this is recursive, it could be driven to stack overflow */
1386 if (STACK_TOO_DEEP(nfa->v->re))
1387 {
1388 NERR(REG_ETOOBIG);
1389 return;
1390 }
1391
1392 if (s->tmp != NULL)
1393 return; /* already done */
1394
1395 s->tmp = (stmp == NULL) ? newstate(nfa) : stmp;
1396 if (s->tmp == NULL)
1397 {
1398 assert(NISERR());
1399 return;
1400 }
1401
1402 for (a = s->outs; a != NULL && !NISERR(); a = a->outchain)
1403 {
1404 duptraverse(nfa, a->to, (struct state *) NULL);
1405 if (NISERR())
1406 break;
1407 assert(a->to->tmp != NULL);
1408 cparc(nfa, a, s->tmp, a->to->tmp);
1409 }
1410}
1411
1412/*
1413 * removeconstraints - remove any constraints in an NFA
1414 *
1415 * Constraint arcs are replaced by empty arcs, essentially treating all
1416 * constraints as automatically satisfied.
1417 */
1418static void
1419removeconstraints(struct nfa *nfa,
1420 struct state *start, /* process subNFA starting here */
1421 struct state *stop) /* and stopping here */
1422{
1423 if (start == stop)
1424 return;
1425
1426 stop->tmp = stop;
1427 removetraverse(nfa, start);
1428 /* done, except for clearing out the tmp pointers */
1429
1430 stop->tmp = NULL;
1431 cleartraverse(nfa, start);
1432}
1433
1434/*
1435 * removetraverse - recursive heart of removeconstraints
1436 */
1437static void
1438removetraverse(struct nfa *nfa,
1439 struct state *s)
1440{
1441 struct arc *a;
1442 struct arc *oa;
1443
1444 /* Since this is recursive, it could be driven to stack overflow */
1445 if (STACK_TOO_DEEP(nfa->v->re))
1446 {
1447 NERR(REG_ETOOBIG);
1448 return;
1449 }
1450
1451 if (s->tmp != NULL)
1452 return; /* already done */
1453
1454 s->tmp = s;
1455 for (a = s->outs; a != NULL && !NISERR(); a = oa)
1456 {
1457 removetraverse(nfa, a->to);
1458 if (NISERR())
1459 break;
1460 oa = a->outchain;
1461 switch (a->type)
1462 {
1463 case PLAIN:
1464 case EMPTY:
1465 case CANTMATCH:
1466 /* nothing to do */
1467 break;
1468 case AHEAD:
1469 case BEHIND:
1470 case '^':
1471 case '$':
1472 case LACON:
1473 /* replace it */
1474 newarc(nfa, EMPTY, 0, s, a->to);
1475 freearc(nfa, a);
1476 break;
1477 default:
1478 NERR(REG_ASSERT);
1479 break;
1480 }
1481 }
1482}
1483
1484/*
1485 * cleartraverse - recursive cleanup for algorithms that leave tmp ptrs set
1486 */
1487static void
1488cleartraverse(struct nfa *nfa,
1489 struct state *s)
1490{
1491 struct arc *a;
1492
1493 /* Since this is recursive, it could be driven to stack overflow */
1494 if (STACK_TOO_DEEP(nfa->v->re))
1495 {
1496 NERR(REG_ETOOBIG);
1497 return;
1498 }
1499
1500 if (s->tmp == NULL)
1501 return;
1502 s->tmp = NULL;
1503
1504 for (a = s->outs; a != NULL; a = a->outchain)
1505 cleartraverse(nfa, a->to);
1506}
1507
1508/*
1509 * single_color_transition - does getting from s1 to s2 cross one PLAIN arc?
1510 *
1511 * If traversing from s1 to s2 requires a single PLAIN match (possibly of any
1512 * of a set of colors), return a state whose outarc list contains only PLAIN
1513 * arcs of those color(s). Otherwise return NULL.
1514 *
1515 * This is used before optimizing the NFA, so there may be EMPTY arcs, which
1516 * we should ignore; the possibility of an EMPTY is why the result state could
1517 * be different from s1.
1518 *
1519 * It's worth troubling to handle multiple parallel PLAIN arcs here because a
1520 * bracket construct such as [abc] might yield either one or several parallel
1521 * PLAIN arcs depending on earlier atoms in the expression. We'd rather that
1522 * that implementation detail not create user-visible performance differences.
1523 */
1524static struct state *
1525single_color_transition(struct state *s1, struct state *s2)
1526{
1527 struct arc *a;
1528
1529 /* Ignore leading EMPTY arc, if any */
1530 if (s1->nouts == 1 && s1->outs->type == EMPTY)
1531 s1 = s1->outs->to;
1532 /* Likewise for any trailing EMPTY arc */
1533 if (s2->nins == 1 && s2->ins->type == EMPTY)
1534 s2 = s2->ins->from;
1535 /* Perhaps we could have a single-state loop in between, if so reject */
1536 if (s1 == s2)
1537 return NULL;
1538 /* s1 must have at least one outarc... */
1539 if (s1->outs == NULL)
1540 return NULL;
1541 /* ... and they must all be PLAIN arcs to s2 */
1542 for (a = s1->outs; a != NULL; a = a->outchain)
1543 {
1544 if (a->type != PLAIN || a->to != s2)
1545 return NULL;
1546 }
1547 /* OK, return s1 as the possessor of the relevant outarcs */
1548 return s1;
1549}
1550
1551/*
1552 * specialcolors - fill in special colors for an NFA
1553 */
1554static void
1555specialcolors(struct nfa *nfa)
1556{
1557 /* false colors for BOS, BOL, EOS, EOL */
1558 if (nfa->parent == NULL)
1559 {
1560 nfa->bos[0] = pseudocolor(nfa->cm);
1561 nfa->bos[1] = pseudocolor(nfa->cm);
1562 nfa->eos[0] = pseudocolor(nfa->cm);
1563 nfa->eos[1] = pseudocolor(nfa->cm);
1564 }
1565 else
1566 {
1567 assert(nfa->parent->bos[0] != COLORLESS);
1568 nfa->bos[0] = nfa->parent->bos[0];
1569 assert(nfa->parent->bos[1] != COLORLESS);
1570 nfa->bos[1] = nfa->parent->bos[1];
1571 assert(nfa->parent->eos[0] != COLORLESS);
1572 nfa->eos[0] = nfa->parent->eos[0];
1573 assert(nfa->parent->eos[1] != COLORLESS);
1574 nfa->eos[1] = nfa->parent->eos[1];
1575 }
1576}
1577
1578/*
1579 * optimize - optimize an NFA
1580 *
1581 * The main goal of this function is not so much "optimization" (though it
1582 * does try to get rid of useless NFA states) as reducing the NFA to a form
1583 * the regex executor can handle. The executor, and indeed the cNFA format
1584 * that is its input, can only handle PLAIN and LACON arcs. The output of
1585 * the regex parser also includes EMPTY (do-nothing) arcs, as well as
1586 * ^, $, AHEAD, and BEHIND constraint arcs, which we must get rid of here.
1587 * We first get rid of EMPTY arcs and then deal with the constraint arcs.
1588 * The hardest part of either job is to get rid of circular loops of the
1589 * target arc type. We would have to do that in any case, though, as such a
1590 * loop would otherwise allow the executor to cycle through the loop endlessly
1591 * without making any progress in the input string.
1592 */
1593static long /* re_info bits */
1594optimize(struct nfa *nfa,
1595 FILE *f) /* for debug output; NULL none */
1596{
1597#ifdef REG_DEBUG
1598 int verbose = (f != NULL) ? 1 : 0;
1599
1600 if (verbose)
1601 fprintf(f, "\ninitial cleanup:\n");
1602#endif
1603 /* If we have any CANTMATCH arcs, drop them; but this is uncommon */
1604 if (nfa->flags & HASCANTMATCH)
1605 {
1606 removecantmatch(nfa);
1607 nfa->flags &= ~HASCANTMATCH;
1608 }
1609 cleanup(nfa); /* may simplify situation */
1610#ifdef REG_DEBUG
1611 if (verbose)
1612 dumpnfa(nfa, f);
1613 if (verbose)
1614 fprintf(f, "\nempties:\n");
1615#endif
1616 fixempties(nfa, f); /* get rid of EMPTY arcs */
1617#ifdef REG_DEBUG
1618 if (verbose)
1619 fprintf(f, "\nconstraints:\n");
1620#endif
1621 fixconstraintloops(nfa, f); /* get rid of constraint loops */
1622 pullback(nfa, f); /* pull back constraints backward */
1623 pushfwd(nfa, f); /* push fwd constraints forward */
1624#ifdef REG_DEBUG
1625 if (verbose)
1626 fprintf(f, "\nfinal cleanup:\n");
1627#endif
1628 cleanup(nfa); /* final tidying */
1629#ifdef REG_DEBUG
1630 if (verbose)
1631 dumpnfa(nfa, f);
1632#endif
1633 return analyze(nfa); /* and analysis */
1634}
1635
1636/*
1637 * pullback - pull back constraints backward to eliminate them
1638 */
1639static void
1640pullback(struct nfa *nfa,
1641 FILE *f) /* for debug output; NULL none */
1642{
1643 struct state *s;
1644 struct state *nexts;
1645 struct arc *a;
1646 struct arc *nexta;
1647 struct state *intermediates;
1648 int progress;
1649
1650 /* find and pull until there are no more */
1651 do
1652 {
1653 progress = 0;
1654 for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
1655 {
1656 nexts = s->next;
1657 intermediates = NULL;
1658 for (a = s->outs; a != NULL && !NISERR(); a = nexta)
1659 {
1660 nexta = a->outchain;
1661 if (a->type == '^' || a->type == BEHIND)
1662 if (pull(nfa, a, &intermediates))
1663 progress = 1;
1664 }
1665 /* clear tmp fields of intermediate states created here */
1666 while (intermediates != NULL)
1667 {
1668 struct state *ns = intermediates->tmp;
1669
1670 intermediates->tmp = NULL;
1671 intermediates = ns;
1672 }
1673 /* if s is now useless, get rid of it */
1674 if ((s->nins == 0 || s->nouts == 0) && !s->flag)
1675 dropstate(nfa, s);
1676 }
1677 if (progress && f != NULL)
1678 dumpnfa(nfa, f);
1679 } while (progress && !NISERR());
1680 if (NISERR())
1681 return;
1682
1683 /*
1684 * Any ^ constraints we were able to pull to the start state can now be
1685 * replaced by PLAIN arcs referencing the BOS or BOL colors. There should
1686 * be no other ^ or BEHIND arcs left in the NFA, though we do not check
1687 * that here (compact() will fail if so).
1688 */
1689 for (a = nfa->pre->outs; a != NULL; a = nexta)
1690 {
1691 nexta = a->outchain;
1692 if (a->type == '^')
1693 {
1694 assert(a->co == 0 || a->co == 1);
1695 newarc(nfa, PLAIN, nfa->bos[a->co], a->from, a->to);
1696 freearc(nfa, a);
1697 }
1698 }
1699}
1700
1701/*
1702 * pull - pull a back constraint backward past its source state
1703 *
1704 * Returns 1 if successful (which it always is unless the source is the
1705 * start state or we have an internal error), 0 if nothing happened.
1706 *
1707 * A significant property of this function is that it deletes no pre-existing
1708 * states, and no outarcs of the constraint's from state other than the given
1709 * constraint arc. This makes the loops in pullback() safe, at the cost that
1710 * we may leave useless states behind. Therefore, we leave it to pullback()
1711 * to delete such states.
1712 *
1713 * If the from state has multiple back-constraint outarcs, and/or multiple
1714 * compatible constraint inarcs, we only need to create one new intermediate
1715 * state per combination of predecessor and successor states. *intermediates
1716 * points to a list of such intermediate states for this from state (chained
1717 * through their tmp fields).
1718 */
1719static int
1720pull(struct nfa *nfa,
1721 struct arc *con,
1722 struct state **intermediates)
1723{
1724 struct state *from = con->from;
1725 struct state *to = con->to;
1726 struct arc *a;
1727 struct arc *nexta;
1728 struct state *s;
1729
1730 assert(from != to); /* should have gotten rid of this earlier */
1731 if (from->flag) /* can't pull back beyond start */
1732 return 0;
1733 if (from->nins == 0)
1734 { /* unreachable */
1735 freearc(nfa, con);
1736 return 1;
1737 }
1738
1739 /*
1740 * First, clone from state if necessary to avoid other outarcs. This may
1741 * seem wasteful, but it simplifies the logic, and we'll get rid of the
1742 * clone state again at the bottom.
1743 */
1744 if (from->nouts > 1)
1745 {
1746 s = newstate(nfa);
1747 if (NISERR())
1748 return 0;
1749 copyins(nfa, from, s); /* duplicate inarcs */
1750 cparc(nfa, con, s, to); /* move constraint arc */
1751 freearc(nfa, con);
1752 if (NISERR())
1753 return 0;
1754 from = s;
1755 con = from->outs;
1756 }
1757 assert(from->nouts == 1);
1758
1759 /* propagate the constraint into the from state's inarcs */
1760 for (a = from->ins; a != NULL && !NISERR(); a = nexta)
1761 {
1762 nexta = a->inchain;
1763 switch (combine(nfa, con, a))
1764 {
1765 case INCOMPATIBLE: /* destroy the arc */
1766 freearc(nfa, a);
1767 break;
1768 case SATISFIED: /* no action needed */
1769 break;
1770 case COMPATIBLE: /* swap the two arcs, more or less */
1771 /* need an intermediate state, but might have one already */
1772 for (s = *intermediates; s != NULL; s = s->tmp)
1773 {
1774 assert(s->nins > 0 && s->nouts > 0);
1775 if (s->ins->from == a->from && s->outs->to == to)
1776 break;
1777 }
1778 if (s == NULL)
1779 {
1780 s = newstate(nfa);
1781 if (NISERR())
1782 return 0;
1783 s->tmp = *intermediates;
1784 *intermediates = s;
1785 }
1786 cparc(nfa, con, a->from, s);
1787 cparc(nfa, a, s, to);
1788 freearc(nfa, a);
1789 break;
1790 case REPLACEARC: /* replace arc's color */
1791 newarc(nfa, a->type, con->co, a->from, to);
1792 freearc(nfa, a);
1793 break;
1794 default:
1795 assert(NOTREACHED);
1796 break;
1797 }
1798 }
1799
1800 /* remaining inarcs, if any, incorporate the constraint */
1801 moveins(nfa, from, to);
1802 freearc(nfa, con);
1803 /* from state is now useless, but we leave it to pullback() to clean up */
1804 return 1;
1805}
1806
1807/*
1808 * pushfwd - push forward constraints forward to eliminate them
1809 */
1810static void
1811pushfwd(struct nfa *nfa,
1812 FILE *f) /* for debug output; NULL none */
1813{
1814 struct state *s;
1815 struct state *nexts;
1816 struct arc *a;
1817 struct arc *nexta;
1818 struct state *intermediates;
1819 int progress;
1820
1821 /* find and push until there are no more */
1822 do
1823 {
1824 progress = 0;
1825 for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
1826 {
1827 nexts = s->next;
1828 intermediates = NULL;
1829 for (a = s->ins; a != NULL && !NISERR(); a = nexta)
1830 {
1831 nexta = a->inchain;
1832 if (a->type == '$' || a->type == AHEAD)
1833 if (push(nfa, a, &intermediates))
1834 progress = 1;
1835 }
1836 /* clear tmp fields of intermediate states created here */
1837 while (intermediates != NULL)
1838 {
1839 struct state *ns = intermediates->tmp;
1840
1841 intermediates->tmp = NULL;
1842 intermediates = ns;
1843 }
1844 /* if s is now useless, get rid of it */
1845 if ((s->nins == 0 || s->nouts == 0) && !s->flag)
1846 dropstate(nfa, s);
1847 }
1848 if (progress && f != NULL)
1849 dumpnfa(nfa, f);
1850 } while (progress && !NISERR());
1851 if (NISERR())
1852 return;
1853
1854 /*
1855 * Any $ constraints we were able to push to the post state can now be
1856 * replaced by PLAIN arcs referencing the EOS or EOL colors. There should
1857 * be no other $ or AHEAD arcs left in the NFA, though we do not check
1858 * that here (compact() will fail if so).
1859 */
1860 for (a = nfa->post->ins; a != NULL; a = nexta)
1861 {
1862 nexta = a->inchain;
1863 if (a->type == '$')
1864 {
1865 assert(a->co == 0 || a->co == 1);
1866 newarc(nfa, PLAIN, nfa->eos[a->co], a->from, a->to);
1867 freearc(nfa, a);
1868 }
1869 }
1870}
1871
1872/*
1873 * push - push a forward constraint forward past its destination state
1874 *
1875 * Returns 1 if successful (which it always is unless the destination is the
1876 * post state or we have an internal error), 0 if nothing happened.
1877 *
1878 * A significant property of this function is that it deletes no pre-existing
1879 * states, and no inarcs of the constraint's to state other than the given
1880 * constraint arc. This makes the loops in pushfwd() safe, at the cost that
1881 * we may leave useless states behind. Therefore, we leave it to pushfwd()
1882 * to delete such states.
1883 *
1884 * If the to state has multiple forward-constraint inarcs, and/or multiple
1885 * compatible constraint outarcs, we only need to create one new intermediate
1886 * state per combination of predecessor and successor states. *intermediates
1887 * points to a list of such intermediate states for this to state (chained
1888 * through their tmp fields).
1889 */
1890static int
1891push(struct nfa *nfa,
1892 struct arc *con,
1893 struct state **intermediates)
1894{
1895 struct state *from = con->from;
1896 struct state *to = con->to;
1897 struct arc *a;
1898 struct arc *nexta;
1899 struct state *s;
1900
1901 assert(to != from); /* should have gotten rid of this earlier */
1902 if (to->flag) /* can't push forward beyond end */
1903 return 0;
1904 if (to->nouts == 0)
1905 { /* dead end */
1906 freearc(nfa, con);
1907 return 1;
1908 }
1909
1910 /*
1911 * First, clone to state if necessary to avoid other inarcs. This may
1912 * seem wasteful, but it simplifies the logic, and we'll get rid of the
1913 * clone state again at the bottom.
1914 */
1915 if (to->nins > 1)
1916 {
1917 s = newstate(nfa);
1918 if (NISERR())
1919 return 0;
1920 copyouts(nfa, to, s); /* duplicate outarcs */
1921 cparc(nfa, con, from, s); /* move constraint arc */
1922 freearc(nfa, con);
1923 if (NISERR())
1924 return 0;
1925 to = s;
1926 con = to->ins;
1927 }
1928 assert(to->nins == 1);
1929
1930 /* propagate the constraint into the to state's outarcs */
1931 for (a = to->outs; a != NULL && !NISERR(); a = nexta)
1932 {
1933 nexta = a->outchain;
1934 switch (combine(nfa, con, a))
1935 {
1936 case INCOMPATIBLE: /* destroy the arc */
1937 freearc(nfa, a);
1938 break;
1939 case SATISFIED: /* no action needed */
1940 break;
1941 case COMPATIBLE: /* swap the two arcs, more or less */
1942 /* need an intermediate state, but might have one already */
1943 for (s = *intermediates; s != NULL; s = s->tmp)
1944 {
1945 assert(s->nins > 0 && s->nouts > 0);
1946 if (s->ins->from == from && s->outs->to == a->to)
1947 break;
1948 }
1949 if (s == NULL)
1950 {
1951 s = newstate(nfa);
1952 if (NISERR())
1953 return 0;
1954 s->tmp = *intermediates;
1955 *intermediates = s;
1956 }
1957 cparc(nfa, con, s, a->to);
1958 cparc(nfa, a, from, s);
1959 freearc(nfa, a);
1960 break;
1961 case REPLACEARC: /* replace arc's color */
1962 newarc(nfa, a->type, con->co, from, a->to);
1963 freearc(nfa, a);
1964 break;
1965 default:
1966 assert(NOTREACHED);
1967 break;
1968 }
1969 }
1970
1971 /* remaining outarcs, if any, incorporate the constraint */
1972 moveouts(nfa, to, from);
1973 freearc(nfa, con);
1974 /* to state is now useless, but we leave it to pushfwd() to clean up */
1975 return 1;
1976}
1977
1978/*
1979 * combine - constraint lands on an arc, what happens?
1980 *
1981 * #def INCOMPATIBLE 1 // destroys arc
1982 * #def SATISFIED 2 // constraint satisfied
1983 * #def COMPATIBLE 3 // compatible but not satisfied yet
1984 * #def REPLACEARC 4 // replace arc's color with constraint color
1985 */
1986static int
1987combine(struct nfa *nfa,
1988 struct arc *con,
1989 struct arc *a)
1990{
1991#define CA(ct,at) (((ct)<<CHAR_BIT) | (at))
1992
1993 switch (CA(con->type, a->type))
1994 {
1995 case CA('^', PLAIN): /* newlines are handled separately */
1996 case CA('$', PLAIN):
1997 return INCOMPATIBLE;
1998 break;
1999 case CA(AHEAD, PLAIN): /* color constraints meet colors */
2000 case CA(BEHIND, PLAIN):
2001 if (con->co == a->co)
2002 return SATISFIED;
2003 if (con->co == RAINBOW)
2004 {
2005 /* con is satisfied unless arc's color is a pseudocolor */
2006 if (!(nfa->cm->cd[a->co].flags & PSEUDO))
2007 return SATISFIED;
2008 }
2009 else if (a->co == RAINBOW)
2010 {
2011 /* con is incompatible if it's for a pseudocolor */
2012 /* (this is hypothetical; we make no such constraints today) */
2013 if (nfa->cm->cd[con->co].flags & PSEUDO)
2014 return INCOMPATIBLE;
2015 /* otherwise, constraint constrains arc to be only its color */
2016 return REPLACEARC;
2017 }
2018 return INCOMPATIBLE;
2019 break;
2020 case CA('^', '^'): /* collision, similar constraints */
2021 case CA('$', '$'):
2022 if (con->co == a->co) /* true duplication */
2023 return SATISFIED;
2024 return INCOMPATIBLE;
2025 break;
2026 case CA(AHEAD, AHEAD): /* collision, similar constraints */
2027 case CA(BEHIND, BEHIND):
2028 if (con->co == a->co) /* true duplication */
2029 return SATISFIED;
2030 if (con->co == RAINBOW)
2031 {
2032 /* con is satisfied unless arc's color is a pseudocolor */
2033 if (!(nfa->cm->cd[a->co].flags & PSEUDO))
2034 return SATISFIED;
2035 }
2036 else if (a->co == RAINBOW)
2037 {
2038 /* con is incompatible if it's for a pseudocolor */
2039 /* (this is hypothetical; we make no such constraints today) */
2040 if (nfa->cm->cd[con->co].flags & PSEUDO)
2041 return INCOMPATIBLE;
2042 /* otherwise, constraint constrains arc to be only its color */
2043 return REPLACEARC;
2044 }
2045 return INCOMPATIBLE;
2046 break;
2047 case CA('^', BEHIND): /* collision, dissimilar constraints */
2048 case CA(BEHIND, '^'):
2049 case CA('$', AHEAD):
2050 case CA(AHEAD, '$'):
2051 return INCOMPATIBLE;
2052 break;
2053 case CA('^', '$'): /* constraints passing each other */
2054 case CA('^', AHEAD):
2055 case CA(BEHIND, '$'):
2056 case CA(BEHIND, AHEAD):
2057 case CA('$', '^'):
2058 case CA('$', BEHIND):
2059 case CA(AHEAD, '^'):
2060 case CA(AHEAD, BEHIND):
2061 case CA('^', LACON):
2062 case CA(BEHIND, LACON):
2063 case CA('$', LACON):
2064 case CA(AHEAD, LACON):
2065 return COMPATIBLE;
2066 break;
2067 }
2068 assert(NOTREACHED);
2069 return INCOMPATIBLE; /* for benefit of blind compilers */
2070}
2071
2072/*
2073 * fixempties - get rid of EMPTY arcs
2074 */
2075static void
2076fixempties(struct nfa *nfa,
2077 FILE *f) /* for debug output; NULL none */
2078{
2079 struct state *s;
2080 struct state *s2;
2081 struct state *nexts;
2082 struct arc *a;
2083 struct arc *nexta;
2084 int totalinarcs;
2085 struct arc **inarcsorig;
2086 struct arc **arcarray;
2087 int arccount;
2088 int prevnins;
2089 int nskip;
2090
2091 /*
2092 * First, get rid of any states whose sole out-arc is an EMPTY, since
2093 * they're basically just aliases for their successor. The parsing
2094 * algorithm creates enough of these that it's worth special-casing this.
2095 */
2096 for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
2097 {
2098 nexts = s->next;
2099 if (s->flag || s->nouts != 1)
2100 continue;
2101 a = s->outs;
2102 assert(a != NULL && a->outchain == NULL);
2103 if (a->type != EMPTY)
2104 continue;
2105 if (s != a->to)
2106 moveins(nfa, s, a->to);
2107 dropstate(nfa, s);
2108 }
2109
2110 /*
2111 * Similarly, get rid of any state with a single EMPTY in-arc, by folding
2112 * it into its predecessor.
2113 */
2114 for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
2115 {
2116 nexts = s->next;
2117 /* while we're at it, ensure tmp fields are clear for next step */
2118 assert(s->tmp == NULL);
2119 if (s->flag || s->nins != 1)
2120 continue;
2121 a = s->ins;
2122 assert(a != NULL && a->inchain == NULL);
2123 if (a->type != EMPTY)
2124 continue;
2125 if (s != a->from)
2126 moveouts(nfa, s, a->from);
2127 dropstate(nfa, s);
2128 }
2129
2130 if (NISERR())
2131 return;
2132
2133 /*
2134 * For each remaining NFA state, find all other states from which it is
2135 * reachable by a chain of one or more EMPTY arcs. Then generate new arcs
2136 * that eliminate the need for each such chain.
2137 *
2138 * We could replace a chain of EMPTY arcs that leads from a "from" state
2139 * to a "to" state either by pushing non-EMPTY arcs forward (linking
2140 * directly from "from"'s predecessors to "to") or by pulling them back
2141 * (linking directly from "from" to "to"'s successors). We choose to
2142 * always do the former; this choice is somewhat arbitrary, but the
2143 * approach below requires that we uniformly do one or the other.
2144 *
2145 * Suppose we have a chain of N successive EMPTY arcs (where N can easily
2146 * approach the size of the NFA). All of the intermediate states must
2147 * have additional inarcs and outarcs, else they'd have been removed by
2148 * the steps above. Assuming their inarcs are mostly not empties, we will
2149 * add O(N^2) arcs to the NFA, since a non-EMPTY inarc leading to any one
2150 * state in the chain must be duplicated to lead to all its successor
2151 * states as well. So there is no hope of doing less than O(N^2) work;
2152 * however, we should endeavor to keep the big-O cost from being even
2153 * worse than that, which it can easily become without care. In
2154 * particular, suppose we were to copy all S1's inarcs forward to S2, and
2155 * then also to S3, and then later we consider pushing S2's inarcs forward
2156 * to S3. If we include the arcs already copied from S1 in that, we'd be
2157 * doing O(N^3) work. (The duplicate-arc elimination built into newarc()
2158 * and its cohorts would get rid of the extra arcs, but not without cost.)
2159 *
2160 * We can avoid this cost by treating only arcs that existed at the start
2161 * of this phase as candidates to be pushed forward. To identify those,
2162 * we remember the first inarc each state had to start with. We rely on
2163 * the fact that newarc() and friends put new arcs on the front of their
2164 * to-states' inchains, and that this phase never deletes arcs, so that
2165 * the original arcs must be the last arcs in their to-states' inchains.
2166 *
2167 * So the process here is that, for each state in the NFA, we gather up
2168 * all non-EMPTY inarcs of states that can reach the target state via
2169 * EMPTY arcs. We then sort, de-duplicate, and merge these arcs into the
2170 * target state's inchain. (We can safely use sort-merge for this as long
2171 * as we update each state's original-arcs pointer after we add arcs to
2172 * it; the sort step of mergeins probably changed the order of the old
2173 * arcs.)
2174 *
2175 * Another refinement worth making is that, because we only add non-EMPTY
2176 * arcs during this phase, and all added arcs have the same from-state as
2177 * the non-EMPTY arc they were cloned from, we know ahead of time that any
2178 * states having only EMPTY outarcs will be useless for lack of outarcs
2179 * after we drop the EMPTY arcs. (They cannot gain non-EMPTY outarcs if
2180 * they had none to start with.) So we need not bother to update the
2181 * inchains of such states at all.
2182 */
2183
2184 /* Remember the states' first original inarcs */
2185 /* ... and while at it, count how many old inarcs there are altogether */
2186 inarcsorig = (struct arc **) MALLOC(nfa->nstates * sizeof(struct arc *));
2187 if (inarcsorig == NULL)
2188 {
2189 NERR(REG_ESPACE);
2190 return;
2191 }
2192 totalinarcs = 0;
2193 for (s = nfa->states; s != NULL; s = s->next)
2194 {
2195 inarcsorig[s->no] = s->ins;
2196 totalinarcs += s->nins;
2197 }
2198
2199 /*
2200 * Create a workspace for accumulating the inarcs to be added to the
2201 * current target state. totalinarcs is probably a considerable
2202 * overestimate of the space needed, but the NFA is unlikely to be large
2203 * enough at this point to make it worth being smarter.
2204 */
2205 arcarray = (struct arc **) MALLOC(totalinarcs * sizeof(struct arc *));
2206 if (arcarray == NULL)
2207 {
2208 NERR(REG_ESPACE);
2209 FREE(inarcsorig);
2210 return;
2211 }
2212
2213 /* And iterate over the target states */
2214 for (s = nfa->states; s != NULL && !NISERR(); s = s->next)
2215 {
2216 /* Ignore target states without non-EMPTY outarcs, per note above */
2217 if (!s->flag && !hasnonemptyout(s))
2218 continue;
2219
2220 /* Find predecessor states and accumulate their original inarcs */
2221 arccount = 0;
2222 for (s2 = emptyreachable(nfa, s, s, inarcsorig); s2 != s; s2 = nexts)
2223 {
2224 /* Add s2's original inarcs to arcarray[], but ignore empties */
2225 for (a = inarcsorig[s2->no]; a != NULL; a = a->inchain)
2226 {
2227 if (a->type != EMPTY)
2228 arcarray[arccount++] = a;
2229 }
2230
2231 /* Reset the tmp fields as we walk back */
2232 nexts = s2->tmp;
2233 s2->tmp = NULL;
2234 }
2235 s->tmp = NULL;
2236 assert(arccount <= totalinarcs);
2237
2238 /* Remember how many original inarcs this state has */
2239 prevnins = s->nins;
2240
2241 /* Add non-duplicate inarcs to target state */
2242 mergeins(nfa, s, arcarray, arccount);
2243
2244 /* Now we must update the state's inarcsorig pointer */
2245 nskip = s->nins - prevnins;
2246 a = s->ins;
2247 while (nskip-- > 0)
2248 a = a->inchain;
2249 inarcsorig[s->no] = a;
2250 }
2251
2252 FREE(arcarray);
2253 FREE(inarcsorig);
2254
2255 if (NISERR())
2256 return;
2257
2258 /*
2259 * Now remove all the EMPTY arcs, since we don't need them anymore.
2260 */
2261 for (s = nfa->states; s != NULL; s = s->next)
2262 {
2263 for (a = s->outs; a != NULL; a = nexta)
2264 {
2265 nexta = a->outchain;
2266 if (a->type == EMPTY)
2267 freearc(nfa, a);
2268 }
2269 }
2270
2271 /*
2272 * And remove any states that have become useless. (This cleanup is not
2273 * very thorough, and would be even less so if we tried to combine it with
2274 * the previous step; but cleanup() will take care of anything we miss.)
2275 */
2276 for (s = nfa->states; s != NULL; s = nexts)
2277 {
2278 nexts = s->next;
2279 if ((s->nins == 0 || s->nouts == 0) && !s->flag)
2280 dropstate(nfa, s);
2281 }
2282
2283 if (f != NULL)
2284 dumpnfa(nfa, f);
2285}
2286
2287/*
2288 * emptyreachable - recursively find all states that can reach s by EMPTY arcs
2289 *
2290 * The return value is the last such state found. Its tmp field links back
2291 * to the next-to-last such state, and so on back to s, so that all these
2292 * states can be located without searching the whole NFA.
2293 *
2294 * Since this is only used in fixempties(), we pass in the inarcsorig[] array
2295 * maintained by that function. This lets us skip over all new inarcs, which
2296 * are certainly not EMPTY arcs.
2297 *
2298 * The maximum recursion depth here is equal to the length of the longest
2299 * loop-free chain of EMPTY arcs, which is surely no more than the size of
2300 * the NFA ... but that could still be enough to cause trouble.
2301 */
2302static struct state *
2303emptyreachable(struct nfa *nfa,
2304 struct state *s,
2305 struct state *lastfound,
2306 struct arc **inarcsorig)
2307{
2308 struct arc *a;
2309
2310 /* Since this is recursive, it could be driven to stack overflow */
2311 if (STACK_TOO_DEEP(nfa->v->re))
2312 {
2313 NERR(REG_ETOOBIG);
2314 return lastfound;
2315 }
2316
2317 s->tmp = lastfound;
2318 lastfound = s;
2319 for (a = inarcsorig[s->no]; a != NULL; a = a->inchain)
2320 {
2321 if (a->type == EMPTY && a->from->tmp == NULL)
2322 lastfound = emptyreachable(nfa, a->from, lastfound, inarcsorig);
2323 }
2324 return lastfound;
2325}
2326
2327/*
2328 * isconstraintarc - detect whether an arc is of a constraint type
2329 */
2330static inline int
2331isconstraintarc(struct arc *a)
2332{
2333 switch (a->type)
2334 {
2335 case '^':
2336 case '$':
2337 case BEHIND:
2338 case AHEAD:
2339 case LACON:
2340 return 1;
2341 }
2342 return 0;
2343}
2344
2345/*
2346 * hasconstraintout - does state have a constraint out arc?
2347 */
2348static int
2349hasconstraintout(struct state *s)
2350{
2351 struct arc *a;
2352
2353 for (a = s->outs; a != NULL; a = a->outchain)
2354 {
2355 if (isconstraintarc(a))
2356 return 1;
2357 }
2358 return 0;
2359}
2360
2361/*
2362 * fixconstraintloops - get rid of loops containing only constraint arcs
2363 *
2364 * A loop of states that contains only constraint arcs is useless, since
2365 * passing around the loop represents no forward progress. Moreover, it
2366 * would cause infinite looping in pullback/pushfwd, so we need to get rid
2367 * of such loops before doing that.
2368 */
2369static void
2370fixconstraintloops(struct nfa *nfa,
2371 FILE *f) /* for debug output; NULL none */
2372{
2373 struct state *s;
2374 struct state *nexts;
2375 struct arc *a;
2376 struct arc *nexta;
2377 int hasconstraints;
2378
2379 /*
2380 * In the trivial case of a state that loops to itself, we can just drop
2381 * the constraint arc altogether. This is worth special-casing because
2382 * such loops are far more common than loops containing multiple states.
2383 * While we're at it, note whether any constraint arcs survive.
2384 */
2385 hasconstraints = 0;
2386 for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
2387 {
2388 nexts = s->next;
2389 /* while we're at it, ensure tmp fields are clear for next step */
2390 assert(s->tmp == NULL);
2391 for (a = s->outs; a != NULL && !NISERR(); a = nexta)
2392 {
2393 nexta = a->outchain;
2394 if (isconstraintarc(a))
2395 {
2396 if (a->to == s)
2397 freearc(nfa, a);
2398 else
2399 hasconstraints = 1;
2400 }
2401 }
2402 /* If we removed all the outarcs, the state is useless. */
2403 if (s->nouts == 0 && !s->flag)
2404 dropstate(nfa, s);
2405 }
2406
2407 /* Nothing to do if no remaining constraint arcs */
2408 if (NISERR() || !hasconstraints)
2409 return;
2410
2411 /*
2412 * Starting from each remaining NFA state, search outwards for a
2413 * constraint loop. If we find a loop, break the loop, then start the
2414 * search over. (We could possibly retain some state from the first scan,
2415 * but it would complicate things greatly, and multi-state constraint
2416 * loops are rare enough that it's not worth optimizing the case.)
2417 */
2418restart:
2419 for (s = nfa->states; s != NULL && !NISERR(); s = s->next)
2420 {
2421 if (findconstraintloop(nfa, s))
2422 goto restart;
2423 }
2424
2425 if (NISERR())
2426 return;
2427
2428 /*
2429 * Now remove any states that have become useless. (This cleanup is not
2430 * very thorough, and would be even less so if we tried to combine it with
2431 * the previous step; but cleanup() will take care of anything we miss.)
2432 *
2433 * Because findconstraintloop intentionally doesn't reset all tmp fields,
2434 * we have to clear them after it's done. This is a convenient place to
2435 * do that, too.
2436 */
2437 for (s = nfa->states; s != NULL; s = nexts)
2438 {
2439 nexts = s->next;
2440 s->tmp = NULL;
2441 if ((s->nins == 0 || s->nouts == 0) && !s->flag)
2442 dropstate(nfa, s);
2443 }
2444
2445 if (f != NULL)
2446 dumpnfa(nfa, f);
2447}
2448
2449/*
2450 * findconstraintloop - recursively find a loop of constraint arcs
2451 *
2452 * If we find a loop, break it by calling breakconstraintloop(), then
2453 * return 1; otherwise return 0.
2454 *
2455 * State tmp fields are guaranteed all NULL on a success return, because
2456 * breakconstraintloop does that. After a failure return, any state that
2457 * is known not to be part of a loop is marked with s->tmp == s; this allows
2458 * us not to have to re-prove that fact on later calls. (This convention is
2459 * workable because we already eliminated single-state loops.)
2460 *
2461 * Note that the found loop doesn't necessarily include the first state we
2462 * are called on. Any loop reachable from that state will do.
2463 *
2464 * The maximum recursion depth here is one more than the length of the longest
2465 * loop-free chain of constraint arcs, which is surely no more than the size
2466 * of the NFA ... but that could still be enough to cause trouble.
2467 */
2468static int
2469findconstraintloop(struct nfa *nfa, struct state *s)
2470{
2471 struct arc *a;
2472
2473 /* Since this is recursive, it could be driven to stack overflow */
2474 if (STACK_TOO_DEEP(nfa->v->re))
2475 {
2476 NERR(REG_ETOOBIG);
2477 return 1; /* to exit as quickly as possible */
2478 }
2479
2480 if (s->tmp != NULL)
2481 {
2482 /* Already proven uninteresting? */
2483 if (s->tmp == s)
2484 return 0;
2485 /* Found a loop involving s */
2486 breakconstraintloop(nfa, s);
2487 /* The tmp fields have been cleaned up by breakconstraintloop */
2488 return 1;
2489 }
2490 for (a = s->outs; a != NULL; a = a->outchain)
2491 {
2492 if (isconstraintarc(a))
2493 {
2494 struct state *sto = a->to;
2495
2496 assert(sto != s);
2497 s->tmp = sto;
2498 if (findconstraintloop(nfa, sto))
2499 return 1;
2500 }
2501 }
2502
2503 /*
2504 * If we get here, no constraint loop exists leading out from s. Mark it
2505 * with s->tmp == s so we need not rediscover that fact again later.
2506 */
2507 s->tmp = s;
2508 return 0;
2509}
2510
2511/*
2512 * breakconstraintloop - break a loop of constraint arcs
2513 *
2514 * sinitial is any one member state of the loop. Each loop member's tmp
2515 * field links to its successor within the loop. (Note that this function
2516 * will reset all the tmp fields to NULL.)
2517 *
2518 * We can break the loop by, for any one state S1 in the loop, cloning its
2519 * loop successor state S2 (and possibly following states), and then moving
2520 * all S1->S2 constraint arcs to point to the cloned S2. The cloned S2 should
2521 * copy any non-constraint outarcs of S2. Constraint outarcs should be
2522 * dropped if they point back to S1, else they need to be copied as arcs to
2523 * similarly cloned states S3, S4, etc. In general, each cloned state copies
2524 * non-constraint outarcs, drops constraint outarcs that would lead to itself
2525 * or any earlier cloned state, and sends other constraint outarcs to newly
2526 * cloned states. No cloned state will have any inarcs that aren't constraint
2527 * arcs or do not lead from S1 or earlier-cloned states. It's okay to drop
2528 * constraint back-arcs since they would not take us to any state we've not
2529 * already been in; therefore, no new constraint loop is created. In this way
2530 * we generate a modified NFA that can still represent every useful state
2531 * sequence, but not sequences that represent state loops with no consumption
2532 * of input data. Note that the set of cloned states will certainly include
2533 * all of the loop member states other than S1, and it may also include
2534 * non-loop states that are reachable from S2 via constraint arcs. This is
2535 * important because there is no guarantee that findconstraintloop found a
2536 * maximal loop (and searching for one would be NP-hard, so don't try).
2537 * Frequently the "non-loop states" are actually part of a larger loop that
2538 * we didn't notice, and indeed there may be several overlapping loops.
2539 * This technique ensures convergence in such cases, while considering only
2540 * the originally-found loop does not.
2541 *
2542 * If there is only one S1->S2 constraint arc, then that constraint is
2543 * certainly satisfied when we enter any of the clone states. This means that
2544 * in the common case where many of the constraint arcs are identically
2545 * labeled, we can merge together clone states linked by a similarly-labeled
2546 * constraint: if we can get to the first one we can certainly get to the
2547 * second, so there's no need to distinguish. This greatly reduces the number
2548 * of new states needed, so we preferentially break the given loop at a state
2549 * pair where this is true.
2550 *
2551 * Furthermore, it's fairly common to find that a cloned successor state has
2552 * no outarcs, especially if we're a bit aggressive about removing unnecessary
2553 * outarcs. If that happens, then there is simply not any interesting state
2554 * that can be reached through the predecessor's loop arcs, which means we can
2555 * break the loop just by removing those loop arcs, with no new states added.
2556 */
2557static void
2558breakconstraintloop(struct nfa *nfa, struct state *sinitial)
2559{
2560 struct state *s;
2561 struct state *shead;
2562 struct state *stail;
2563 struct state *sclone;
2564 struct state *nexts;
2565 struct arc *refarc;
2566 struct arc *a;
2567 struct arc *nexta;
2568
2569 /*
2570 * Start by identifying which loop step we want to break at.
2571 * Preferentially this is one with only one constraint arc. (XXX are
2572 * there any other secondary heuristics we want to use here?) Set refarc
2573 * to point to the selected lone constraint arc, if there is one.
2574 */
2575 refarc = NULL;
2576 s = sinitial;
2577 do
2578 {
2579 nexts = s->tmp;
2580 assert(nexts != s); /* should not see any one-element loops */
2581 if (refarc == NULL)
2582 {
2583 int narcs = 0;
2584
2585 for (a = s->outs; a != NULL; a = a->outchain)
2586 {
2587 if (a->to == nexts && isconstraintarc(a))
2588 {
2589 refarc = a;
2590 narcs++;
2591 }
2592 }
2593 assert(narcs > 0);
2594 if (narcs > 1)
2595 refarc = NULL; /* multiple constraint arcs here, no good */
2596 }
2597 s = nexts;
2598 } while (s != sinitial);
2599
2600 if (refarc)
2601 {
2602 /* break at the refarc */
2603 shead = refarc->from;
2604 stail = refarc->to;
2605 assert(stail == shead->tmp);
2606 }
2607 else
2608 {
2609 /* for lack of a better idea, break after sinitial */
2610 shead = sinitial;
2611 stail = sinitial->tmp;
2612 }
2613
2614 /*
2615 * Reset the tmp fields so that we can use them for local storage in
2616 * clonesuccessorstates. (findconstraintloop won't mind, since it's just
2617 * going to abandon its search anyway.)
2618 */
2619 for (s = nfa->states; s != NULL; s = s->next)
2620 s->tmp = NULL;
2621
2622 /*
2623 * Recursively build clone state(s) as needed.
2624 */
2625 sclone = newstate(nfa);
2626 if (sclone == NULL)
2627 {
2628 assert(NISERR());
2629 return;
2630 }
2631
2632 clonesuccessorstates(nfa, stail, sclone, shead, refarc,
2633 NULL, NULL, nfa->nstates);
2634
2635 if (NISERR())
2636 return;
2637
2638 /*
2639 * It's possible that sclone has no outarcs at all, in which case it's
2640 * useless. (We don't try extremely hard to get rid of useless states
2641 * here, but this is an easy and fairly common case.)
2642 */
2643 if (sclone->nouts == 0)
2644 {
2645 freestate(nfa, sclone);
2646 sclone = NULL;
2647 }
2648
2649 /*
2650 * Move shead's constraint-loop arcs to point to sclone, or just drop them
2651 * if we discovered we don't need sclone.
2652 */
2653 for (a = shead->outs; a != NULL; a = nexta)
2654 {
2655 nexta = a->outchain;
2656 if (a->to == stail && isconstraintarc(a))
2657 {
2658 if (sclone)
2659 cparc(nfa, a, shead, sclone);
2660 freearc(nfa, a);
2661 if (NISERR())
2662 break;
2663 }
2664 }
2665}
2666
2667/*
2668 * clonesuccessorstates - create a tree of constraint-arc successor states
2669 *
2670 * ssource is the state to be cloned, and sclone is the state to copy its
2671 * outarcs into. sclone's inarcs, if any, should already be set up.
2672 *
2673 * spredecessor is the original predecessor state that we are trying to build
2674 * successors for (it may not be the immediate predecessor of ssource).
2675 * refarc, if not NULL, is the original constraint arc that is known to have
2676 * been traversed out of spredecessor to reach the successor(s).
2677 *
2678 * For each cloned successor state, we transiently create a "donemap" that is
2679 * a boolean array showing which source states we've already visited for this
2680 * clone state. This prevents infinite recursion as well as useless repeat
2681 * visits to the same state subtree (which can add up fast, since typical NFAs
2682 * have multiple redundant arc pathways). Each donemap is a char array
2683 * indexed by state number. The donemaps are all of the same size "nstates",
2684 * which is nfa->nstates as of the start of the recursion. This is enough to
2685 * have entries for all pre-existing states, but *not* entries for clone
2686 * states created during the recursion. That's okay since we have no need to
2687 * mark those.
2688 *
2689 * curdonemap is NULL when recursing to a new sclone state, or sclone's
2690 * donemap when we are recursing without having created a new state (which we
2691 * do when we decide we can merge a successor state into the current clone
2692 * state). outerdonemap is NULL at the top level and otherwise the parent
2693 * clone state's donemap.
2694 *
2695 * The successor states we create and fill here form a strict tree structure,
2696 * with each state having exactly one predecessor, except that the toplevel
2697 * state has no inarcs as yet (breakconstraintloop will add its inarcs from
2698 * spredecessor after we're done). Thus, we can examine sclone's inarcs back
2699 * to the root, plus refarc if any, to identify the set of constraints already
2700 * known valid at the current point. This allows us to avoid generating extra
2701 * successor states.
2702 */
2703static void
2704clonesuccessorstates(struct nfa *nfa,
2705 struct state *ssource,
2706 struct state *sclone,
2707 struct state *spredecessor,
2708 struct arc *refarc,
2709 char *curdonemap,
2710 char *outerdonemap,
2711 int nstates)
2712{
2713 char *donemap;
2714 struct arc *a;
2715
2716 /* Since this is recursive, it could be driven to stack overflow */
2717 if (STACK_TOO_DEEP(nfa->v->re))
2718 {
2719 NERR(REG_ETOOBIG);
2720 return;
2721 }
2722
2723 /* If this state hasn't already got a donemap, create one */
2724 donemap = curdonemap;
2725 if (donemap == NULL)
2726 {
2727 donemap = (char *) MALLOC(nstates * sizeof(char));
2728 if (donemap == NULL)
2729 {
2730 NERR(REG_ESPACE);
2731 return;
2732 }
2733
2734 if (outerdonemap != NULL)
2735 {
2736 /*
2737 * Not at outermost recursion level, so copy the outer level's
2738 * donemap; this ensures that we see states in process of being
2739 * visited at outer levels, or already merged into predecessor
2740 * states, as ones we shouldn't traverse back to.
2741 */
2742 memcpy(donemap, outerdonemap, nstates * sizeof(char));
2743 }
2744 else
2745 {
2746 /* At outermost level, only spredecessor is off-limits */
2747 memset(donemap, 0, nstates * sizeof(char));
2748 assert(spredecessor->no < nstates);
2749 donemap[spredecessor->no] = 1;
2750 }
2751 }
2752
2753 /* Mark ssource as visited in the donemap */
2754 assert(ssource->no < nstates);
2755 assert(donemap[ssource->no] == 0);
2756 donemap[ssource->no] = 1;
2757
2758 /*
2759 * We proceed by first cloning all of ssource's outarcs, creating new
2760 * clone states as needed but not doing more with them than that. Then in
2761 * a second pass, recurse to process the child clone states. This allows
2762 * us to have only one child clone state per reachable source state, even
2763 * when there are multiple outarcs leading to the same state. Also, when
2764 * we do visit a child state, its set of inarcs is known exactly, which
2765 * makes it safe to apply the constraint-is-already-checked optimization.
2766 * Also, this ensures that we've merged all the states we can into the
2767 * current clone before we recurse to any children, thus possibly saving
2768 * them from making extra images of those states.
2769 *
2770 * While this function runs, child clone states of the current state are
2771 * marked by setting their tmp fields to point to the original state they
2772 * were cloned from. This makes it possible to detect multiple outarcs
2773 * leading to the same state, and also makes it easy to distinguish clone
2774 * states from original states (which will have tmp == NULL).
2775 */
2776 for (a = ssource->outs; a != NULL && !NISERR(); a = a->outchain)
2777 {
2778 struct state *sto = a->to;
2779
2780 /*
2781 * We do not consider cloning successor states that have no constraint
2782 * outarcs; just link to them as-is. They cannot be part of a
2783 * constraint loop so there is no need to make copies. In particular,
2784 * this rule keeps us from trying to clone the post state, which would
2785 * be a bad idea.
2786 */
2787 if (isconstraintarc(a) && hasconstraintout(sto))
2788 {
2789 struct state *prevclone;
2790 int canmerge;
2791 struct arc *a2;
2792
2793 /*
2794 * Back-link constraint arcs must not be followed. Nor is there a
2795 * need to revisit states previously merged into this clone.
2796 */
2797 assert(sto->no < nstates);
2798 if (donemap[sto->no] != 0)
2799 continue;
2800
2801 /*
2802 * Check whether we already have a child clone state for this
2803 * source state.
2804 */
2805 prevclone = NULL;
2806 for (a2 = sclone->outs; a2 != NULL; a2 = a2->outchain)
2807 {
2808 if (a2->to->tmp == sto)
2809 {
2810 prevclone = a2->to;
2811 break;
2812 }
2813 }
2814
2815 /*
2816 * If this arc is labeled the same as refarc, or the same as any
2817 * arc we must have traversed to get to sclone, then no additional
2818 * constraints need to be met to get to sto, so we should just
2819 * merge its outarcs into sclone.
2820 */
2821 if (refarc && a->type == refarc->type && a->co == refarc->co)
2822 canmerge = 1;
2823 else
2824 {
2825 struct state *s;
2826
2827 canmerge = 0;
2828 for (s = sclone; s->ins; s = s->ins->from)
2829 {
2830 if (s->nins == 1 &&
2831 a->type == s->ins->type && a->co == s->ins->co)
2832 {
2833 canmerge = 1;
2834 break;
2835 }
2836 }
2837 }
2838
2839 if (canmerge)
2840 {
2841 /*
2842 * We can merge into sclone. If we previously made a child
2843 * clone state, drop it; there's no need to visit it. (This
2844 * can happen if ssource has multiple pathways to sto, and we
2845 * only just now found one that is provably a no-op.)
2846 */
2847 if (prevclone)
2848 dropstate(nfa, prevclone); /* kills our outarc, too */
2849
2850 /* Recurse to merge sto's outarcs into sclone */
2851 clonesuccessorstates(nfa,
2852 sto,
2853 sclone,
2854 spredecessor,
2855 refarc,
2856 donemap,
2857 outerdonemap,
2858 nstates);
2859 /* sto should now be marked as previously visited */
2860 assert(NISERR() || donemap[sto->no] == 1);
2861 }
2862 else if (prevclone)
2863 {
2864 /*
2865 * We already have a clone state for this successor, so just
2866 * make another arc to it.
2867 */
2868 cparc(nfa, a, sclone, prevclone);
2869 }
2870 else
2871 {
2872 /*
2873 * We need to create a new successor clone state.
2874 */
2875 struct state *stoclone;
2876
2877 stoclone = newstate(nfa);
2878 if (stoclone == NULL)
2879 {
2880 assert(NISERR());
2881 break;
2882 }
2883 /* Mark it as to what it's a clone of */
2884 stoclone->tmp = sto;
2885 /* ... and add the outarc leading to it */
2886 cparc(nfa, a, sclone, stoclone);
2887 }
2888 }
2889 else
2890 {
2891 /*
2892 * Non-constraint outarcs just get copied to sclone, as do outarcs
2893 * leading to states with no constraint outarc.
2894 */
2895 cparc(nfa, a, sclone, sto);
2896 }
2897 }
2898
2899 /*
2900 * If we are at outer level for this clone state, recurse to all its child
2901 * clone states, clearing their tmp fields as we go. (If we're not
2902 * outermost for sclone, leave this to be done by the outer call level.)
2903 * Note that if we have multiple outarcs leading to the same clone state,
2904 * it will only be recursed-to once.
2905 */
2906 if (curdonemap == NULL)
2907 {
2908 for (a = sclone->outs; a != NULL && !NISERR(); a = a->outchain)
2909 {
2910 struct state *stoclone = a->to;
2911 struct state *sto = stoclone->tmp;
2912
2913 if (sto != NULL)
2914 {
2915 stoclone->tmp = NULL;
2916 clonesuccessorstates(nfa,
2917 sto,
2918 stoclone,
2919 spredecessor,
2920 refarc,
2921 NULL,
2922 donemap,
2923 nstates);
2924 }
2925 }
2926
2927 /* Don't forget to free sclone's donemap when done with it */
2928 FREE(donemap);
2929 }
2930}
2931
2932/*
2933 * removecantmatch - remove CANTMATCH arcs, which are no longer useful
2934 * once we are done with the parsing phase. (We need them only to
2935 * preserve connectedness of NFA subgraphs during parsing.)
2936 */
2937static void
2938removecantmatch(struct nfa *nfa)
2939{
2940 struct state *s;
2941
2942 for (s = nfa->states; s != NULL; s = s->next)
2943 {
2944 struct arc *a;
2945 struct arc *nexta;
2946
2947 for (a = s->outs; a != NULL; a = nexta)
2948 {
2949 nexta = a->outchain;
2950 if (a->type == CANTMATCH)
2951 {
2952 freearc(nfa, a);
2953 if (NISERR())
2954 return;
2955 }
2956 }
2957 }
2958}
2959
2960/*
2961 * cleanup - clean up NFA after optimizations
2962 */
2963static void
2964cleanup(struct nfa *nfa)
2965{
2966 struct state *s;
2967 struct state *nexts;
2968 int n;
2969
2970 if (NISERR())
2971 return;
2972
2973 /* clear out unreachable or dead-end states */
2974 /* use pre to mark reachable, then post to mark can-reach-post */
2975 markreachable(nfa, nfa->pre, (struct state *) NULL, nfa->pre);
2976 markcanreach(nfa, nfa->post, nfa->pre, nfa->post);
2977 for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
2978 {
2979 nexts = s->next;
2980 if (s->tmp != nfa->post && !s->flag)
2981 dropstate(nfa, s);
2982 }
2983 assert(NISERR() || nfa->post->nins == 0 || nfa->post->tmp == nfa->post);
2984 cleartraverse(nfa, nfa->pre);
2985 assert(NISERR() || nfa->post->nins == 0 || nfa->post->tmp == NULL);
2986 /* the nins==0 (final unreachable) case will be caught later */
2987
2988 /* renumber surviving states */
2989 n = 0;
2990 for (s = nfa->states; s != NULL; s = s->next)
2991 s->no = n++;
2992 nfa->nstates = n;
2993}
2994
2995/*
2996 * markreachable - recursive marking of reachable states
2997 */
2998static void
2999markreachable(struct nfa *nfa,
3000 struct state *s,
3001 struct state *okay, /* consider only states with this mark */
3002 struct state *mark) /* the value to mark with */
3003{
3004 struct arc *a;
3005
3006 /* Since this is recursive, it could be driven to stack overflow */
3007 if (STACK_TOO_DEEP(nfa->v->re))
3008 {
3009 NERR(REG_ETOOBIG);
3010 return;
3011 }
3012
3013 if (s->tmp != okay)
3014 return;
3015 s->tmp = mark;
3016
3017 for (a = s->outs; a != NULL; a = a->outchain)
3018 markreachable(nfa, a->to, okay, mark);
3019}
3020
3021/*
3022 * markcanreach - recursive marking of states which can reach here
3023 */
3024static void
3025markcanreach(struct nfa *nfa,
3026 struct state *s,
3027 struct state *okay, /* consider only states with this mark */
3028 struct state *mark) /* the value to mark with */
3029{
3030 struct arc *a;
3031
3032 /* Since this is recursive, it could be driven to stack overflow */
3033 if (STACK_TOO_DEEP(nfa->v->re))
3034 {
3035 NERR(REG_ETOOBIG);
3036 return;
3037 }
3038
3039 if (s->tmp != okay)
3040 return;
3041 s->tmp = mark;
3042
3043 for (a = s->ins; a != NULL; a = a->inchain)
3044 markcanreach(nfa, a->from, okay, mark);
3045}
3046
3047/*
3048 * analyze - ascertain potentially-useful facts about an optimized NFA
3049 */
3050static long /* re_info bits to be ORed in */
3051analyze(struct nfa *nfa)
3052{
3053 struct arc *a;
3054 struct arc *aa;
3055
3056 if (NISERR())
3057 return 0;
3058
3059 /* Detect whether NFA can't match anything */
3060 if (nfa->pre->outs == NULL)
3061 return REG_UIMPOSSIBLE;
3062
3063 /* Detect whether NFA matches all strings (possibly with length bounds) */
3064 checkmatchall(nfa);
3065
3066 /* Detect whether NFA can possibly match a zero-length string */
3067 for (a = nfa->pre->outs; a != NULL; a = a->outchain)
3068 for (aa = a->to->outs; aa != NULL; aa = aa->outchain)
3069 if (aa->to == nfa->post)
3070 return REG_UEMPTYMATCH;
3071 return 0;
3072}
3073
3074/*
3075 * checkmatchall - does the NFA represent no more than a string length test?
3076 *
3077 * If so, set nfa->minmatchall and nfa->maxmatchall correctly (they are -1
3078 * to begin with) and set the MATCHALL bit in nfa->flags.
3079 *
3080 * To succeed, we require all arcs to be PLAIN RAINBOW arcs, except for those
3081 * for pseudocolors (i.e., BOS/BOL/EOS/EOL). We must be able to reach the
3082 * post state via RAINBOW arcs, and if there are any loops in the graph, they
3083 * must be loop-to-self arcs, ensuring that each loop iteration consumes
3084 * exactly one character. (Longer loops are problematic because they create
3085 * non-consecutive possible match lengths; we have no good way to represent
3086 * that situation for lengths beyond the DUPINF limit.)
3087 *
3088 * Pseudocolor arcs complicate things a little. We know that they can only
3089 * appear as pre-state outarcs (for BOS/BOL) or post-state inarcs (for
3090 * EOS/EOL). There, they must exactly replicate the parallel RAINBOW arcs,
3091 * e.g. if the pre state has one RAINBOW outarc to state 2, it must have BOS
3092 * and BOL outarcs to state 2, and no others. Missing or extra pseudocolor
3093 * arcs can occur, meaning that the NFA involves some constraint on the
3094 * adjacent characters, which makes it not a matchall NFA.
3095 */
3096static void
3097checkmatchall(struct nfa *nfa)
3098{
3099 bool **haspaths;
3100 struct state *s;
3101 int i;
3102
3103 /*
3104 * If there are too many states, don't bother trying to detect matchall.
3105 * This limit serves to bound the time and memory we could consume below.
3106 * Note that even if the graph is all-RAINBOW, if there are significantly
3107 * more than DUPINF states then it's likely that there are paths of length
3108 * more than DUPINF, which would force us to fail anyhow. In practice,
3109 * plausible ways of writing a matchall regex with maximum finite path
3110 * length K tend not to have very many more than K states.
3111 */
3112 if (nfa->nstates > DUPINF * 2)
3113 return;
3114
3115 /*
3116 * First, scan all the states to verify that only RAINBOW arcs appear,
3117 * plus pseudocolor arcs adjacent to the pre and post states. This lets
3118 * us quickly eliminate most cases that aren't matchall NFAs.
3119 */
3120 for (s = nfa->states; s != NULL; s = s->next)
3121 {
3122 struct arc *a;
3123
3124 for (a = s->outs; a != NULL; a = a->outchain)
3125 {
3126 if (a->type != PLAIN)
3127 return; /* any LACONs make it non-matchall */
3128 if (a->co != RAINBOW)
3129 {
3130 if (nfa->cm->cd[a->co].flags & PSEUDO)
3131 {
3132 /*
3133 * Pseudocolor arc: verify it's in a valid place (this
3134 * seems quite unlikely to fail, but let's be sure).
3135 */
3136 if (s == nfa->pre &&
3137 (a->co == nfa->bos[0] || a->co == nfa->bos[1]))
3138 /* okay BOS/BOL arc */ ;
3139 else if (a->to == nfa->post &&
3140 (a->co == nfa->eos[0] || a->co == nfa->eos[1]))
3141 /* okay EOS/EOL arc */ ;
3142 else
3143 return; /* unexpected pseudocolor arc */
3144 /* We'll check these arcs some more below. */
3145 }
3146 else
3147 return; /* any other color makes it non-matchall */
3148 }
3149 }
3150 /* Also, assert that the tmp fields are available for use. */
3151 assert(s->tmp == NULL);
3152 }
3153
3154 /*
3155 * The next cheapest check we can make is to verify that the BOS/BOL
3156 * outarcs of the pre state reach the same states as its RAINBOW outarcs.
3157 * If they don't, the NFA expresses some constraints on the character
3158 * before the matched string, making it non-matchall. Likewise, the
3159 * EOS/EOL inarcs of the post state must match its RAINBOW inarcs.
3160 */
3161 if (!check_out_colors_match(nfa->pre, RAINBOW, nfa->bos[0]) ||
3162 !check_out_colors_match(nfa->pre, RAINBOW, nfa->bos[1]) ||
3163 !check_in_colors_match(nfa->post, RAINBOW, nfa->eos[0]) ||
3164 !check_in_colors_match(nfa->post, RAINBOW, nfa->eos[1]))
3165 return;
3166
3167 /*
3168 * Initialize an array of path-length arrays, in which
3169 * checkmatchall_recurse will return per-state results. This lets us
3170 * memo-ize the recursive search and avoid exponential time consumption.
3171 */
3172 haspaths = (bool **) MALLOC(nfa->nstates * sizeof(bool *));
3173 if (haspaths == NULL)
3174 return; /* fail quietly */
3175 memset(haspaths, 0, nfa->nstates * sizeof(bool *));
3176
3177 /*
3178 * Recursively search the graph for all-RAINBOW paths to the "post" state,
3179 * starting at the "pre" state, and computing the lengths of the paths.
3180 * (Given the preceding checks, there should be at least one such path.
3181 * However we could get back a false result anyway, in case there are
3182 * multi-state loops, paths exceeding DUPINF+1 length, or non-algorithmic
3183 * failures such as ENOMEM.)
3184 */
3185 if (checkmatchall_recurse(nfa, nfa->pre, haspaths))
3186 {
3187 /* The useful result is the path length array for the pre state */
3188 bool *haspath = haspaths[nfa->pre->no];
3189 int minmatch,
3190 maxmatch,
3191 morematch;
3192
3193 assert(haspath != NULL);
3194
3195 /*
3196 * haspath[] now represents the set of possible path lengths; but we
3197 * want to reduce that to a min and max value, because it doesn't seem
3198 * worth complicating regexec.c to deal with nonconsecutive possible
3199 * match lengths. Find min and max of first run of lengths, then
3200 * verify there are no nonconsecutive lengths.
3201 */
3202 for (minmatch = 0; minmatch <= DUPINF + 1; minmatch++)
3203 {
3204 if (haspath[minmatch])
3205 break;
3206 }
3207 assert(minmatch <= DUPINF + 1); /* else checkmatchall_recurse lied */
3208 for (maxmatch = minmatch; maxmatch < DUPINF + 1; maxmatch++)
3209 {
3210 if (!haspath[maxmatch + 1])
3211 break;
3212 }
3213 for (morematch = maxmatch + 1; morematch <= DUPINF + 1; morematch++)
3214 {
3215 if (haspath[morematch])
3216 {
3217 haspath = NULL; /* fail, there are nonconsecutive lengths */
3218 break;
3219 }
3220 }
3221
3222 if (haspath != NULL)
3223 {
3224 /*
3225 * Success, so record the info. Here we have a fine point: the
3226 * path length from the pre state includes the pre-to-initial
3227 * transition, so it's one more than the actually matched string
3228 * length. (We avoided counting the final-to-post transition
3229 * within checkmatchall_recurse, but not this one.) This is why
3230 * checkmatchall_recurse allows one more level of path length than
3231 * might seem necessary. This decrement also takes care of
3232 * converting checkmatchall_recurse's definition of "infinity" as
3233 * "DUPINF+1" to our normal representation as "DUPINF".
3234 */
3235 assert(minmatch > 0); /* else pre and post states were adjacent */
3236 nfa->minmatchall = minmatch - 1;
3237 nfa->maxmatchall = maxmatch - 1;
3238 nfa->flags |= MATCHALL;
3239 }
3240 }
3241
3242 /* Clean up */
3243 for (i = 0; i < nfa->nstates; i++)
3244 {
3245 if (haspaths[i] != NULL)
3246 FREE(haspaths[i]);
3247 }
3248 FREE(haspaths);
3249}
3250
3251/*
3252 * checkmatchall_recurse - recursive search for checkmatchall
3253 *
3254 * s is the state to be examined in this recursion level.
3255 * haspaths[] is an array of per-state exit path length arrays.
3256 *
3257 * We return true if the search was performed successfully, false if
3258 * we had to fail because of multi-state loops or other internal reasons.
3259 * (Because "dead" states that can't reach the post state have been
3260 * eliminated, and we already verified that only RAINBOW and matching
3261 * pseudocolor arcs exist, every state should have RAINBOW path(s) to
3262 * the post state. Hence we take a false result from recursive calls
3263 * as meaning that we'd better fail altogether, not just that that
3264 * particular state can't reach the post state.)
3265 *
3266 * On success, we store a malloc'd result array in haspaths[s->no],
3267 * showing the possible path lengths from s to the post state.
3268 * Each state's haspath[] array is of length DUPINF+2. The entries from
3269 * k = 0 to DUPINF are true if there is an all-RAINBOW path of length k
3270 * from this state to the string end. haspath[DUPINF+1] is true if all
3271 * path lengths >= DUPINF+1 are possible. (Situations that cannot be
3272 * represented under these rules cause failure.)
3273 *
3274 * checkmatchall is responsible for eventually freeing the haspath[] arrays.
3275 */
3276static bool
3277checkmatchall_recurse(struct nfa *nfa, struct state *s, bool **haspaths)
3278{
3279 bool result = false;
3280 bool foundloop = false;
3281 bool *haspath;
3282 struct arc *a;
3283
3284 /*
3285 * Since this is recursive, it could be driven to stack overflow. But we
3286 * need not treat that as a hard failure; just deem the NFA non-matchall.
3287 */
3288 if (STACK_TOO_DEEP(nfa->v->re))
3289 return false;
3290
3291 /* In case the search takes a long time, check for cancel */
3292 INTERRUPT(nfa->v->re);
3293
3294 /* Create a haspath array for this state */
3295 haspath = (bool *) MALLOC((DUPINF + 2) * sizeof(bool));
3296 if (haspath == NULL)
3297 return false; /* again, treat as non-matchall */
3298 memset(haspath, 0, (DUPINF + 2) * sizeof(bool));
3299
3300 /* Mark this state as being visited */
3301 assert(s->tmp == NULL);
3302 s->tmp = s;
3303
3304 for (a = s->outs; a != NULL; a = a->outchain)
3305 {
3306 if (a->co != RAINBOW)
3307 continue; /* ignore pseudocolor arcs */
3308 if (a->to == nfa->post)
3309 {
3310 /* We found an all-RAINBOW path to the post state */
3311 result = true;
3312
3313 /*
3314 * Mark this state as being zero steps away from the string end
3315 * (the transition to the post state isn't counted).
3316 */
3317 haspath[0] = true;
3318 }
3319 else if (a->to == s)
3320 {
3321 /* We found a cycle of length 1, which we'll deal with below. */
3322 foundloop = true;
3323 }
3324 else if (a->to->tmp != NULL)
3325 {
3326 /* It's busy, so we found a cycle of length > 1, so fail. */
3327 result = false;
3328 break;
3329 }
3330 else
3331 {
3332 /* Consider paths forward through this to-state. */
3333 bool *nexthaspath;
3334 int i;
3335
3336 /* If to-state was not already visited, recurse */
3337 if (haspaths[a->to->no] == NULL)
3338 {
3339 result = checkmatchall_recurse(nfa, a->to, haspaths);
3340 /* Fail if any recursive path fails */
3341 if (!result)
3342 break;
3343 }
3344 else
3345 {
3346 /* The previous visit must have found path(s) to the end */
3347 result = true;
3348 }
3349 assert(a->to->tmp == NULL);
3350 nexthaspath = haspaths[a->to->no];
3351 assert(nexthaspath != NULL);
3352
3353 /*
3354 * Now, for every path of length i from a->to to the string end,
3355 * there is a path of length i + 1 from s to the string end.
3356 */
3357 if (nexthaspath[DUPINF] != nexthaspath[DUPINF + 1])
3358 {
3359 /*
3360 * a->to has a path of length exactly DUPINF, but not longer;
3361 * or it has paths of all lengths > DUPINF but not one of
3362 * exactly that length. In either case, we cannot represent
3363 * the possible path lengths from s correctly, so fail.
3364 */
3365 result = false;
3366 break;
3367 }
3368 /* Merge knowledge of these path lengths into what we have */
3369 for (i = 0; i < DUPINF; i++)
3370 haspath[i + 1] |= nexthaspath[i];
3371 /* Infinity + 1 is still infinity */
3372 haspath[DUPINF + 1] |= nexthaspath[DUPINF + 1];
3373 }
3374 }
3375
3376 if (result && foundloop)
3377 {
3378 /*
3379 * If there is a length-1 loop at this state, then find the shortest
3380 * known path length to the end. The loop means that every larger
3381 * path length is possible, too. (It doesn't matter whether any of
3382 * the longer lengths were already known possible.)
3383 */
3384 int i;
3385
3386 for (i = 0; i <= DUPINF; i++)
3387 {
3388 if (haspath[i])
3389 break;
3390 }
3391 for (i++; i <= DUPINF + 1; i++)
3392 haspath[i] = true;
3393 }
3394
3395 /* Report out the completed path length map */
3396 assert(s->no < nfa->nstates);
3397 assert(haspaths[s->no] == NULL);
3398 haspaths[s->no] = haspath;
3399
3400 /* Mark state no longer busy */
3401 s->tmp = NULL;
3402
3403 return result;
3404}
3405
3406/*
3407 * check_out_colors_match - subroutine for checkmatchall
3408 *
3409 * Check whether the set of states reachable from s by arcs of color co1
3410 * is equivalent to the set reachable by arcs of color co2.
3411 * checkmatchall already verified that all of the NFA's arcs are PLAIN,
3412 * so we need not examine arc types here.
3413 */
3414static bool
3415check_out_colors_match(struct state *s, color co1, color co2)
3416{
3417 bool result = true;
3418 struct arc *a;
3419
3420 /*
3421 * To do this in linear time, we assume that the NFA contains no duplicate
3422 * arcs. Run through the out-arcs, marking states reachable by arcs of
3423 * color co1. Run through again, un-marking states reachable by arcs of
3424 * color co2; if we see a not-marked state, we know this co2 arc is
3425 * unmatched. Then run through again, checking for still-marked states,
3426 * and in any case leaving all the tmp fields reset to NULL.
3427 */
3428 for (a = s->outs; a != NULL; a = a->outchain)
3429 {
3430 if (a->co == co1)
3431 {
3432 assert(a->to->tmp == NULL);
3433 a->to->tmp = a->to;
3434 }
3435 }
3436 for (a = s->outs; a != NULL; a = a->outchain)
3437 {
3438 if (a->co == co2)
3439 {
3440 if (a->to->tmp != NULL)
3441 a->to->tmp = NULL;
3442 else
3443 result = false; /* unmatched co2 arc */
3444 }
3445 }
3446 for (a = s->outs; a != NULL; a = a->outchain)
3447 {
3448 if (a->co == co1)
3449 {
3450 if (a->to->tmp != NULL)
3451 {
3452 result = false; /* unmatched co1 arc */
3453 a->to->tmp = NULL;
3454 }
3455 }
3456 }
3457 return result;
3458}
3459
3460/*
3461 * check_in_colors_match - subroutine for checkmatchall
3462 *
3463 * Check whether the set of states that can reach s by arcs of color co1
3464 * is equivalent to the set that can reach s by arcs of color co2.
3465 * checkmatchall already verified that all of the NFA's arcs are PLAIN,
3466 * so we need not examine arc types here.
3467 */
3468static bool
3469check_in_colors_match(struct state *s, color co1, color co2)
3470{
3471 bool result = true;
3472 struct arc *a;
3473
3474 /*
3475 * Identical algorithm to check_out_colors_match, except examine the
3476 * from-states of s' inarcs.
3477 */
3478 for (a = s->ins; a != NULL; a = a->inchain)
3479 {
3480 if (a->co == co1)
3481 {
3482 assert(a->from->tmp == NULL);
3483 a->from->tmp = a->from;
3484 }
3485 }
3486 for (a = s->ins; a != NULL; a = a->inchain)
3487 {
3488 if (a->co == co2)
3489 {
3490 if (a->from->tmp != NULL)
3491 a->from->tmp = NULL;
3492 else
3493 result = false; /* unmatched co2 arc */
3494 }
3495 }
3496 for (a = s->ins; a != NULL; a = a->inchain)
3497 {
3498 if (a->co == co1)
3499 {
3500 if (a->from->tmp != NULL)
3501 {
3502 result = false; /* unmatched co1 arc */
3503 a->from->tmp = NULL;
3504 }
3505 }
3506 }
3507 return result;
3508}
3509
3510/*
3511 * compact - construct the compact representation of an NFA
3512 */
3513static void
3514compact(struct nfa *nfa,
3515 struct cnfa *cnfa)
3516{
3517 struct state *s;
3518 struct arc *a;
3519 size_t nstates;
3520 size_t narcs;
3521 struct carc *ca;
3522 struct carc *first;
3523
3524 assert(!NISERR());
3525
3526 nstates = 0;
3527 narcs = 0;
3528 for (s = nfa->states; s != NULL; s = s->next)
3529 {
3530 nstates++;
3531 narcs += s->nouts + 1; /* need one extra for endmarker */
3532 }
3533
3534 cnfa->stflags = (char *) MALLOC(nstates * sizeof(char));
3535 cnfa->states = (struct carc **) MALLOC(nstates * sizeof(struct carc *));
3536 cnfa->arcs = (struct carc *) MALLOC(narcs * sizeof(struct carc));
3537 if (cnfa->stflags == NULL || cnfa->states == NULL || cnfa->arcs == NULL)
3538 {
3539 if (cnfa->stflags != NULL)
3540 FREE(cnfa->stflags);
3541 if (cnfa->states != NULL)
3542 FREE(cnfa->states);
3543 if (cnfa->arcs != NULL)
3544 FREE(cnfa->arcs);
3545 NERR(REG_ESPACE);
3546 return;
3547 }
3548 cnfa->nstates = nstates;
3549 cnfa->pre = nfa->pre->no;
3550 cnfa->post = nfa->post->no;
3551 cnfa->bos[0] = nfa->bos[0];
3552 cnfa->bos[1] = nfa->bos[1];
3553 cnfa->eos[0] = nfa->eos[0];
3554 cnfa->eos[1] = nfa->eos[1];
3555 cnfa->ncolors = maxcolor(nfa->cm) + 1;
3556 cnfa->flags = nfa->flags;
3557 cnfa->minmatchall = nfa->minmatchall;
3558 cnfa->maxmatchall = nfa->maxmatchall;
3559
3560 ca = cnfa->arcs;
3561 for (s = nfa->states; s != NULL; s = s->next)
3562 {
3563 assert((size_t) s->no < nstates);
3564 cnfa->stflags[s->no] = 0;
3565 cnfa->states[s->no] = ca;
3566 first = ca;
3567 for (a = s->outs; a != NULL; a = a->outchain)
3568 switch (a->type)
3569 {
3570 case PLAIN:
3571 ca->co = a->co;
3572 ca->to = a->to->no;
3573 ca++;
3574 break;
3575 case LACON:
3576 assert(s->no != cnfa->pre);
3577 assert(a->co >= 0);
3578 ca->co = (color) (cnfa->ncolors + a->co);
3579 ca->to = a->to->no;
3580 ca++;
3581 cnfa->flags |= HASLACONS;
3582 break;
3583 default:
3584 NERR(REG_ASSERT);
3585 return;
3586 }
3587 carcsort(first, ca - first);
3588 ca->co = COLORLESS;
3589 ca->to = 0;
3590 ca++;
3591 }
3592 assert(ca == &cnfa->arcs[narcs]);
3593 assert(cnfa->nstates != 0);
3594
3595 /* mark no-progress states */
3596 for (a = nfa->pre->outs; a != NULL; a = a->outchain)
3597 cnfa->stflags[a->to->no] = CNFA_NOPROGRESS;
3598 cnfa->stflags[nfa->pre->no] = CNFA_NOPROGRESS;
3599}
3600
3601/*
3602 * carcsort - sort compacted-NFA arcs by color
3603 */
3604static void
3605carcsort(struct carc *first, size_t n)
3606{
3607 if (n > 1)
3608 qsort(first, n, sizeof(struct carc), carc_cmp);
3609}
3610
3611static int
3612carc_cmp(const void *a, const void *b)
3613{
3614 const struct carc *aa = (const struct carc *) a;
3615 const struct carc *bb = (const struct carc *) b;
3616
3617 if (aa->co < bb->co)
3618 return -1;
3619 if (aa->co > bb->co)
3620 return +1;
3621 if (aa->to < bb->to)
3622 return -1;
3623 if (aa->to > bb->to)
3624 return +1;
3625 /* This is unreached, since there should be no duplicate arcs now: */
3626 return 0;
3627}
3628
3629/*
3630 * freecnfa - free a compacted NFA
3631 */
3632static void
3633freecnfa(struct cnfa *cnfa)
3634{
3635 assert(!NULLCNFA(*cnfa)); /* not empty already */
3636 FREE(cnfa->stflags);
3637 FREE(cnfa->states);
3638 FREE(cnfa->arcs);
3639 ZAPCNFA(*cnfa);
3640}
3641
3642/*
3643 * dumpnfa - dump an NFA in human-readable form
3644 */
3645static void
3646dumpnfa(struct nfa *nfa,
3647 FILE *f)
3648{
3649#ifdef REG_DEBUG
3650 struct state *s;
3651 int nstates = 0;
3652 int narcs = 0;
3653
3654 fprintf(f, "pre %d, post %d", nfa->pre->no, nfa->post->no);
3655 if (nfa->bos[0] != COLORLESS)
3656 fprintf(f, ", bos [%ld]", (long) nfa->bos[0]);
3657 if (nfa->bos[1] != COLORLESS)
3658 fprintf(f, ", bol [%ld]", (long) nfa->bos[1]);
3659 if (nfa->eos[0] != COLORLESS)
3660 fprintf(f, ", eos [%ld]", (long) nfa->eos[0]);
3661 if (nfa->eos[1] != COLORLESS)
3662 fprintf(f, ", eol [%ld]", (long) nfa->eos[1]);
3663 if (nfa->flags & HASLACONS)
3664 fprintf(f, ", haslacons");
3665 if (nfa->flags & HASCANTMATCH)
3666 fprintf(f, ", hascantmatch");
3667 if (nfa->flags & MATCHALL)
3668 {
3669 fprintf(f, ", minmatchall %d", nfa->minmatchall);
3670 if (nfa->maxmatchall == DUPINF)
3671 fprintf(f, ", maxmatchall inf");
3672 else
3673 fprintf(f, ", maxmatchall %d", nfa->maxmatchall);
3674 }
3675 fprintf(f, "\n");
3676 for (s = nfa->states; s != NULL; s = s->next)
3677 {
3678 dumpstate(s, f);
3679 nstates++;
3680 narcs += s->nouts;
3681 }
3682 fprintf(f, "total of %d states, %d arcs\n", nstates, narcs);
3683 if (nfa->parent == NULL)
3684 dumpcolors(nfa->cm, f);
3685 fflush(f);
3686#endif
3687}
3688
3689#ifdef REG_DEBUG /* subordinates of dumpnfa */
3690
3691/*
3692 * dumpstate - dump an NFA state in human-readable form
3693 */
3694static void
3695dumpstate(struct state *s,
3696 FILE *f)
3697{
3698 struct arc *a;
3699
3700 fprintf(f, "%d%s%c", s->no, (s->tmp != NULL) ? "T" : "",
3701 (s->flag) ? s->flag : '.');
3702 if (s->prev != NULL && s->prev->next != s)
3703 fprintf(f, "\tstate chain bad\n");
3704 if (s->nouts == 0)
3705 fprintf(f, "\tno out arcs\n");
3706 else
3707 dumparcs(s, f);
3708 for (a = s->ins; a != NULL; a = a->inchain)
3709 {
3710 if (a->to != s)
3711 fprintf(f, "\tlink from %d to %d on %d's in-chain\n",
3712 a->from->no, a->to->no, s->no);
3713 }
3714 fflush(f);
3715}
3716
3717/*
3718 * dumparcs - dump out-arcs in human-readable form
3719 */
3720static void
3721dumparcs(struct state *s,
3722 FILE *f)
3723{
3724 int pos;
3725 struct arc *a;
3726
3727 /* printing oldest arcs first is usually clearer */
3728 a = s->outs;
3729 assert(a != NULL);
3730 while (a->outchain != NULL)
3731 a = a->outchain;
3732 pos = 1;
3733 do
3734 {
3735 dumparc(a, s, f);
3736 if (pos == 5)
3737 {
3738 fprintf(f, "\n");
3739 pos = 1;
3740 }
3741 else
3742 pos++;
3743 a = a->outchainRev;
3744 } while (a != NULL);
3745 if (pos != 1)
3746 fprintf(f, "\n");
3747}
3748
3749/*
3750 * dumparc - dump one outarc in readable form, including prefixing tab
3751 */
3752static void
3753dumparc(struct arc *a,
3754 struct state *s,
3755 FILE *f)
3756{
3757 struct arc *aa;
3758
3759 fprintf(f, "\t");
3760 switch (a->type)
3761 {
3762 case PLAIN:
3763 if (a->co == RAINBOW)
3764 fprintf(f, "[*]");
3765 else
3766 fprintf(f, "[%ld]", (long) a->co);
3767 break;
3768 case AHEAD:
3769 if (a->co == RAINBOW)
3770 fprintf(f, ">*>");
3771 else
3772 fprintf(f, ">%ld>", (long) a->co);
3773 break;
3774 case BEHIND:
3775 if (a->co == RAINBOW)
3776 fprintf(f, "<*<");
3777 else
3778 fprintf(f, "<%ld<", (long) a->co);
3779 break;
3780 case LACON:
3781 fprintf(f, ":%ld:", (long) a->co);
3782 break;
3783 case '^':
3784 case '$':
3785 fprintf(f, "%c%d", a->type, (int) a->co);
3786 break;
3787 case EMPTY:
3788 break;
3789 case CANTMATCH:
3790 fprintf(f, "X");
3791 break;
3792 default:
3793 fprintf(f, "0x%x/0%lo", a->type, (long) a->co);
3794 break;
3795 }
3796 if (a->from != s)
3797 fprintf(f, "?%d?", a->from->no);
3798 for (aa = a->from->outs; aa != NULL; aa = aa->outchain)
3799 if (aa == a)
3800 break; /* NOTE BREAK OUT */
3801 if (aa == NULL)
3802 fprintf(f, "?!?"); /* missing from out-chain */
3803 fprintf(f, "->");
3804 if (a->to == NULL)
3805 {
3806 fprintf(f, "NULL");
3807 return;
3808 }
3809 fprintf(f, "%d", a->to->no);
3810 for (aa = a->to->ins; aa != NULL; aa = aa->inchain)
3811 if (aa == a)
3812 break; /* NOTE BREAK OUT */
3813 if (aa == NULL)
3814 fprintf(f, "?!?"); /* missing from in-chain */
3815}
3816#endif /* REG_DEBUG */
3817
3818/*
3819 * dumpcnfa - dump a compacted NFA in human-readable form
3820 */
3821#ifdef REG_DEBUG
3822static void
3823dumpcnfa(struct cnfa *cnfa,
3824 FILE *f)
3825{
3826 int st;
3827
3828 fprintf(f, "pre %d, post %d", cnfa->pre, cnfa->post);
3829 if (cnfa->bos[0] != COLORLESS)
3830 fprintf(f, ", bos [%ld]", (long) cnfa->bos[0]);
3831 if (cnfa->bos[1] != COLORLESS)
3832 fprintf(f, ", bol [%ld]", (long) cnfa->bos[1]);
3833 if (cnfa->eos[0] != COLORLESS)
3834 fprintf(f, ", eos [%ld]", (long) cnfa->eos[0]);
3835 if (cnfa->eos[1] != COLORLESS)
3836 fprintf(f, ", eol [%ld]", (long) cnfa->eos[1]);
3837 if (cnfa->flags & HASLACONS)
3838 fprintf(f, ", haslacons");
3839 if (cnfa->flags & MATCHALL)
3840 {
3841 fprintf(f, ", minmatchall %d", cnfa->minmatchall);
3842 if (cnfa->maxmatchall == DUPINF)
3843 fprintf(f, ", maxmatchall inf");
3844 else
3845 fprintf(f, ", maxmatchall %d", cnfa->maxmatchall);
3846 }
3847 fprintf(f, "\n");
3848 for (st = 0; st < cnfa->nstates; st++)
3849 dumpcstate(st, cnfa, f);
3850 fflush(f);
3851}
3852#endif
3853
3854#ifdef REG_DEBUG /* subordinates of dumpcnfa */
3855
3856/*
3857 * dumpcstate - dump a compacted-NFA state in human-readable form
3858 */
3859static void
3860dumpcstate(int st,
3861 struct cnfa *cnfa,
3862 FILE *f)
3863{
3864 struct carc *ca;
3865 int pos;
3866
3867 fprintf(f, "%d%s", st, (cnfa->stflags[st] & CNFA_NOPROGRESS) ? ":" : ".");
3868 pos = 1;
3869 for (ca = cnfa->states[st]; ca->co != COLORLESS; ca++)
3870 {
3871 if (ca->co == RAINBOW)
3872 fprintf(f, "\t[*]->%d", ca->to);
3873 else if (ca->co < cnfa->ncolors)
3874 fprintf(f, "\t[%ld]->%d", (long) ca->co, ca->to);
3875 else
3876 fprintf(f, "\t:%ld:->%d", (long) (ca->co - cnfa->ncolors), ca->to);
3877 if (pos == 5)
3878 {
3879 fprintf(f, "\n");
3880 pos = 1;
3881 }
3882 else
3883 pos++;
3884 }
3885 if (ca == cnfa->states[st] || pos != 1)
3886 fprintf(f, "\n");
3887 fflush(f);
3888}
3889
3890#endif /* REG_DEBUG */
ERR
#define ERR
Definition _int.h:161
cleanup
static void cleanup(void)
Definition bootstrap.c:717
FREE
#define FREE(ptr)
Definition cryptohash.c:37
fprintf
#define fprintf(file, fmt, msg)
Definition cubescan.l:21
start
return str start
Definition hashfn_unstable.h:289
a2
static const FormData_pg_attribute a2
Definition heap.c:157
b
int b
Definition isn.c:74
a
int a
Definition isn.c:73
j
int j
Definition isn.c:78
i
int i
Definition isn.c:77
verbose
static int verbose
Definition pg_basebackup.c:140
progress
static int progress
Definition pgbench.c:262
qsort
#define qsort(a, b, c, d)
Definition port.h:495
fb
static int fb(int x)
Definition preproc-init.c:92
s1
char * s1
Definition preproc-strings.c:46
s2
char * s2
Definition preproc-strings.c:43
colorchain
static void colorchain(struct colormap *cm, struct arc *a)
Definition regc_color.c:984
uncolorchain
static void uncolorchain(struct colormap *cm, struct arc *a)
Definition regc_color.c:1001
maxcolor
static color maxcolor(struct colormap *cm)
Definition regc_color.c:172
pseudocolor
static color pseudocolor(struct colormap *cm)
Definition regc_color.c:312
rainbow
static void rainbow(struct nfa *nfa, struct colormap *cm, int type, color but, struct state *from, struct state *to)
Definition regc_color.c:1031
emptyreachable
static struct state * emptyreachable(struct nfa *nfa, struct state *s, struct state *lastfound, struct arc **inarcsorig)
Definition regc_nfa.c:2303
mergeins
static void mergeins(struct nfa *nfa, struct state *s, struct arc **arcarray, int arccount)
Definition regc_nfa.c:971
NERR
#define NERR(e)
Definition regc_nfa.c:40
cleartraverse
static void cleartraverse(struct nfa *nfa, struct state *s)
Definition regc_nfa.c:1488
cparc
static void cparc(struct nfa *nfa, struct arc *oa, struct state *from, struct state *to)
Definition regc_nfa.c:608
clonesuccessorstates
static void clonesuccessorstates(struct nfa *nfa, struct state *ssource, struct state *sclone, struct state *spredecessor, struct arc *refarc, char *curdonemap, char *outerdonemap, int nstates)
Definition regc_nfa.c:2704
combine
static int combine(struct nfa *nfa, struct arc *con, struct arc *a)
Definition regc_nfa.c:1987
copyouts
static void copyouts(struct nfa *nfa, struct state *oldState, struct state *newState)
Definition regc_nfa.c:1167
findarc
static struct arc * findarc(struct state *s, int type, color co)
Definition regc_nfa.c:592
sortins_cmp
static int sortins_cmp(const void *a, const void *b)
Definition regc_nfa.c:662
BULK_ARC_OP_USE_SORT
#define BULK_ARC_OP_USE_SORT(nsrcarcs, ndestarcs)
Definition regc_nfa.c:758
NISERR
#define NISERR()
Definition regc_nfa.c:39
findconstraintloop
static int findconstraintloop(struct nfa *nfa, struct state *s)
Definition regc_nfa.c:2469
allocarc
static struct arc * allocarc(struct nfa *nfa)
Definition regc_nfa.c:368
compact
static void compact(struct nfa *nfa, struct cnfa *cnfa)
Definition regc_nfa.c:3514
specialcolors
static void specialcolors(struct nfa *nfa)
Definition regc_nfa.c:1555
dupnfa
static void dupnfa(struct nfa *nfa, struct state *start, struct state *stop, struct state *from, struct state *to)
Definition regc_nfa.c:1355
analyze
static long analyze(struct nfa *nfa)
Definition regc_nfa.c:3051
duptraverse
static void duptraverse(struct nfa *nfa, struct state *s, struct state *stmp)
Definition regc_nfa.c:1379
newarc
static void newarc(struct nfa *nfa, int t, color co, struct state *from, struct state *to)
Definition regc_nfa.c:281
checkmatchall_recurse
static bool checkmatchall_recurse(struct nfa *nfa, struct state *s, bool **haspaths)
Definition regc_nfa.c:3277
freenfa
static void freenfa(struct nfa *nfa)
Definition regc_nfa.c:107
single_color_transition
static struct state * single_color_transition(struct state *s1, struct state *s2)
Definition regc_nfa.c:1525
newnfa
static struct nfa * newnfa(struct vars *v, struct colormap *cm, struct nfa *parent)
Definition regc_nfa.c:47
createarc
static void createarc(struct nfa *nfa, int t, color co, struct state *from, struct state *to)
Definition regc_nfa.c:323
isconstraintarc
static int isconstraintarc(struct arc *a)
Definition regc_nfa.c:2331
fixempties
static void fixempties(struct nfa *nfa, FILE *f)
Definition regc_nfa.c:2076
copyins
static void copyins(struct nfa *nfa, struct state *oldState, struct state *newState)
Definition regc_nfa.c:882
push
static int push(struct nfa *nfa, struct arc *con, struct state **intermediates)
Definition regc_nfa.c:1891
moveouts
static void moveouts(struct nfa *nfa, struct state *oldState, struct state *newState)
Definition regc_nfa.c:1066
hasconstraintout
static int hasconstraintout(struct state *s)
Definition regc_nfa.c:2349
freearc
static void freearc(struct nfa *nfa, struct arc *victim)
Definition regc_nfa.c:418
checkmatchall
static void checkmatchall(struct nfa *nfa)
Definition regc_nfa.c:3097
sortins
static void sortins(struct nfa *nfa, struct state *s)
Definition regc_nfa.c:620
cloneouts
static void cloneouts(struct nfa *nfa, struct state *old, struct state *from, struct state *to, int type)
Definition regc_nfa.c:1256
carc_cmp
static int carc_cmp(const void *a, const void *b)
Definition regc_nfa.c:3612
optimize
static long optimize(struct nfa *nfa, FILE *f)
Definition regc_nfa.c:1594
newfstate
static struct state * newfstate(struct nfa *nfa, int flag)
Definition regc_nfa.c:212
removecantmatch
static void removecantmatch(struct nfa *nfa)
Definition regc_nfa.c:2938
sortouts
static void sortouts(struct nfa *nfa, struct state *s)
Definition regc_nfa.c:687
deltraverse
static void deltraverse(struct nfa *nfa, struct state *leftend, struct state *s)
Definition regc_nfa.c:1304
dropstate
static void dropstate(struct nfa *nfa, struct state *s)
Definition regc_nfa.c:226
removetraverse
static void removetraverse(struct nfa *nfa, struct state *s)
Definition regc_nfa.c:1438
pushfwd
static void pushfwd(struct nfa *nfa, FILE *f)
Definition regc_nfa.c:1811
hasnonemptyout
static int hasnonemptyout(struct state *s)
Definition regc_nfa.c:575
pullback
static void pullback(struct nfa *nfa, FILE *f)
Definition regc_nfa.c:1640
markcanreach
static void markcanreach(struct nfa *nfa, struct state *s, struct state *okay, struct state *mark)
Definition regc_nfa.c:3025
delsub
static void delsub(struct nfa *nfa, struct state *lp, struct state *rp)
Definition regc_nfa.c:1281
moveins
static void moveins(struct nfa *nfa, struct state *oldState, struct state *newState)
Definition regc_nfa.c:778
check_in_colors_match
static bool check_in_colors_match(struct state *s, color co1, color co2)
Definition regc_nfa.c:3469
removeconstraints
static void removeconstraints(struct nfa *nfa, struct state *start, struct state *stop)
Definition regc_nfa.c:1419
newstate
static struct state * newstate(struct nfa *nfa)
Definition regc_nfa.c:137
sortouts_cmp
static int sortouts_cmp(const void *a, const void *b)
Definition regc_nfa.c:729
CA
#define CA(ct, at)
carcsort
static void carcsort(struct carc *first, size_t n)
Definition regc_nfa.c:3605
pull
static int pull(struct nfa *nfa, struct arc *con, struct state **intermediates)
Definition regc_nfa.c:1720
changearctarget
static void changearctarget(struct arc *a, struct state *newto)
Definition regc_nfa.c:533
changearcsource
static void changearcsource(struct arc *a, struct state *newfrom)
Definition regc_nfa.c:489
freestate
static void freestate(struct nfa *nfa, struct state *s)
Definition regc_nfa.c:242
dumpnfa
static void dumpnfa(struct nfa *nfa, FILE *f)
Definition regc_nfa.c:3646
markreachable
static void markreachable(struct nfa *nfa, struct state *s, struct state *okay, struct state *mark)
Definition regc_nfa.c:2999
fixconstraintloops
static void fixconstraintloops(struct nfa *nfa, FILE *f)
Definition regc_nfa.c:2370
check_out_colors_match
static bool check_out_colors_match(struct state *s, color co1, color co2)
Definition regc_nfa.c:3415
breakconstraintloop
static void breakconstraintloop(struct nfa *nfa, struct state *sinitial)
Definition regc_nfa.c:2558
freecnfa
static void freecnfa(struct cnfa *cnfa)
Definition regc_nfa.c:3633
SATISFIED
#define SATISFIED
Definition regcomp.c:200
CANTMATCH
#define CANTMATCH
Definition regcomp.c:346
INCOMPATIBLE
#define INCOMPATIBLE
Definition regcomp.c:199
COMPATIBLE
#define COMPATIBLE
Definition regcomp.c:201
EMPTY
#define EMPTY
Definition regcomp.c:329
ISERR
#define ISERR()
Definition regcomp.c:317
REPLACEARC
#define REPLACEARC
Definition regcomp.c:202
BEHIND
#define BEHIND
Definition regcomp.c:343
LACON
#define LACON
Definition regcomp.c:341
AHEAD
#define AHEAD
Definition regcomp.c:342
PLAIN
#define PLAIN
Definition regcomp.c:331
COLORED
#define COLORED(a)
Definition regcomp.c:352
INTERRUPT
#define INTERRUPT(re)
Definition regcustom.h:55
MALLOC
#define MALLOC(n)
Definition regcustom.h:52
assert
#define assert(x)
Definition regcustom.h:57
REG_UEMPTYMATCH
#define REG_UEMPTYMATCH
Definition regex.h:149
REG_ASSERT
#define REG_ASSERT
Definition regex.h:229
REG_UIMPOSSIBLE
#define REG_UIMPOSSIBLE
Definition regex.h:150
REG_ETOOBIG
#define REG_ETOOBIG
Definition regex.h:233
REG_ESPACE
#define REG_ESPACE
Definition regex.h:227
MAXSBSIZE
#define MAXSBSIZE
Definition regguts.h:346
FIRSTSBSIZE
#define FIRSTSBSIZE
Definition regguts.h:345
ARCBATCHSIZE
#define ARCBATCHSIZE(n)
Definition regguts.h:317
PSEUDO
#define PSEUDO
Definition regguts.h:186
RAINBOW
#define RAINBOW
Definition regguts.h:159
STACK_TOO_DEEP
#define STACK_TOO_DEEP(re)
Definition regguts.h:523
ZAPCNFA
#define ZAPCNFA(cnfa)
Definition regguts.h:436
color
short color
Definition regguts.h:155
CNFA_NOPROGRESS
#define CNFA_NOPROGRESS
Definition regguts.h:420
NOTREACHED
#define NOTREACHED
Definition regguts.h:96
COLORLESS
#define COLORLESS
Definition regguts.h:158
DUPINF
#define DUPINF
Definition regguts.h:99
MAXABSIZE
#define MAXABSIZE
Definition regguts.h:320
NULLCNFA
#define NULLCNFA(cnfa)
Definition regguts.h:438
HASCANTMATCH
#define HASCANTMATCH
Definition regguts.h:413
FIRSTABSIZE
#define FIRSTABSIZE
Definition regguts.h:319
HASLACONS
#define HASLACONS
Definition regguts.h:411
REG_MAX_COMPILE_SPACE
#define REG_MAX_COMPILE_SPACE
Definition regguts.h:451
STATEBATCHSIZE
#define STATEBATCHSIZE(n)
Definition regguts.h:343
MATCHALL
#define MATCHALL
Definition regguts.h:412
arc
Definition regguts.h:296
arc::outchain
struct arc * outchain
Definition regguts.h:301
arc::outchainRev
struct arc * outchainRev
Definition regguts.h:302
arc::from
struct state * from
Definition regguts.h:299
arc::type
int type
Definition regguts.h:297
arc::co
color co
Definition regguts.h:298
arc::to
struct state * to
Definition regguts.h:300
arc::inchainRev
struct arc * inchainRev
Definition regguts.h:305
arc::inchain
struct arc * inchain
Definition regguts.h:304
arcbatch::next
struct arcbatch * next
Definition regguts.h:313
arcbatch::narcs
size_t narcs
Definition regguts.h:314
arcbatch::a
struct arc a[FLEXIBLE_ARRAY_MEMBER]
Definition regguts.h:315
carc::co
color co
Definition regguts.h:402
cnfa::pre
int pre
Definition regguts.h:415
cnfa::eos
color eos[2]
Definition regguts.h:418
cnfa::states
struct carc ** states
Definition regguts.h:421
cnfa::ncolors
int ncolors
Definition regguts.h:409
cnfa::maxmatchall
int maxmatchall
Definition regguts.h:426
cnfa::flags
int flags
Definition regguts.h:410
cnfa::post
int post
Definition regguts.h:416
cnfa::minmatchall
int minmatchall
Definition regguts.h:425
cnfa::arcs
struct carc * arcs
Definition regguts.h:423
cnfa::bos
color bos[2]
Definition regguts.h:417
cnfa::nstates
int nstates
Definition regguts.h:408
cnfa::stflags
char * stflags
Definition regguts.h:419
colordesc::flags
int flags
Definition regguts.h:184
colormap::cd
struct colordesc * cd
Definition regguts.h:236
nfa
Definition regguts.h:349
nfa::v
struct vars * v
Definition regguts.h:369
nfa::lastsb
struct statebatch * lastsb
Definition regguts.h:359
nfa::final
struct state * final
Definition regguts.h:352
nfa::lastabused
size_t lastabused
Definition regguts.h:362
nfa::minmatchall
int minmatchall
Definition regguts.h:367
nfa::freearcs
struct arc * freearcs
Definition regguts.h:358
nfa::maxmatchall
int maxmatchall
Definition regguts.h:368
nfa::slast
struct state * slast
Definition regguts.h:356
nfa::bos
color bos[2]
Definition regguts.h:364
nfa::lastsbused
size_t lastsbused
Definition regguts.h:361
nfa::nstates
int nstates
Definition regguts.h:354
nfa::eos
color eos[2]
Definition regguts.h:365
nfa::lastab
struct arcbatch * lastab
Definition regguts.h:360
nfa::states
struct state * states
Definition regguts.h:355
nfa::flags
int flags
Definition regguts.h:366
nfa::post
struct state * post
Definition regguts.h:353
nfa::pre
struct state * pre
Definition regguts.h:350
nfa::cm
struct colormap * cm
Definition regguts.h:363
nfa::parent
struct nfa * parent
Definition regguts.h:370
nfa::freestates
struct state * freestates
Definition regguts.h:357
nfa::init
struct state * init
Definition regguts.h:351
state::nins
int nins
Definition regguts.h:327
state::nouts
int nouts
Definition regguts.h:328
state::flag
char flag
Definition regguts.h:326
state::prev
struct state * prev
Definition regguts.h:334
state::tmp
struct state * tmp
Definition regguts.h:331
state::outs
struct arc * outs
Definition regguts.h:330
state::next
struct state * next
Definition regguts.h:332
state::ins
struct arc * ins
Definition regguts.h:329
state::no
int no
Definition regguts.h:324
statebatch::s
struct state s[FLEXIBLE_ARRAY_MEMBER]
Definition regguts.h:341
statebatch::next
struct statebatch * next
Definition regguts.h:339
statebatch::nstates
size_t nstates
Definition regguts.h:340
vars::spaceused
size_t spaceused
Definition regcomp.c:309
vars::re
regex_t * re
Definition regcomp.c:283
flag
char * flag(int b)
Definition test-ctype.c:33
FREESTATE
#define FREESTATE(state)
Definition tuplesort.c:396
type
const char * type
Definition wait_event_funcs.c:27