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rege_dfa.c
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1 /*
2  * DFA routines
3  * This file is #included by regexec.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/rege_dfa.c
32  *
33  */
34 
35 /*
36  * longest - longest-preferred matching engine
37  *
38  * On success, returns match endpoint address. Returns NULL on no match.
39  * Internal errors also return NULL, with v->err set.
40  */
41 static chr *
42 longest(struct vars *v,
43  struct dfa *d,
44  chr *start, /* where the match should start */
45  chr *stop, /* match must end at or before here */
46  int *hitstopp) /* record whether hit v->stop, if non-NULL */
47 {
48  chr *cp;
49  chr *realstop = (stop == v->stop) ? stop : stop + 1;
50  color co;
51  struct sset *css;
52  struct sset *ss;
53  chr *post;
54  int i;
55  struct colormap *cm = d->cm;
56 
57  /* prevent "uninitialized variable" warnings */
58  if (hitstopp != NULL)
59  *hitstopp = 0;
60 
61  /* if this is a backref to a known string, just match against that */
62  if (d->backno >= 0)
63  {
64  assert((size_t) d->backno < v->nmatch);
65  if (v->pmatch[d->backno].rm_so >= 0)
66  {
67  cp = dfa_backref(v, d, start, start, stop, false);
68  if (cp == v->stop && stop == v->stop && hitstopp != NULL)
69  *hitstopp = 1;
70  return cp;
71  }
72  }
73 
74  /* fast path for matchall NFAs */
75  if (d->cnfa->flags & MATCHALL)
76  {
77  size_t nchr = stop - start;
78  size_t maxmatchall = d->cnfa->maxmatchall;
79 
80  if (nchr < d->cnfa->minmatchall)
81  return NULL;
82  if (maxmatchall == DUPINF)
83  {
84  if (stop == v->stop && hitstopp != NULL)
85  *hitstopp = 1;
86  }
87  else
88  {
89  if (stop == v->stop && nchr <= maxmatchall + 1 && hitstopp != NULL)
90  *hitstopp = 1;
91  if (nchr > maxmatchall)
92  return start + maxmatchall;
93  }
94  return stop;
95  }
96 
97  /* initialize */
98  css = initialize(v, d, start);
99  if (css == NULL)
100  return NULL;
101  cp = start;
102 
103  /* startup */
104  FDEBUG(("+++ startup +++\n"));
105  if (cp == v->start)
106  {
107  co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
108  FDEBUG(("color %ld\n", (long) co));
109  }
110  else
111  {
112  co = GETCOLOR(cm, *(cp - 1));
113  FDEBUG(("char %c, color %ld\n", (char) *(cp - 1), (long) co));
114  }
115  css = miss(v, d, css, co, cp, start);
116  if (css == NULL)
117  return NULL;
118  css->lastseen = cp;
119 
120  /*
121  * This is the main text-scanning loop. It seems worth having two copies
122  * to avoid the overhead of REG_FTRACE tests here, even in REG_DEBUG
123  * builds, when you're not actively tracing.
124  */
125 #ifdef REG_DEBUG
126  if (v->eflags & REG_FTRACE)
127  {
128  while (cp < realstop)
129  {
130  FDEBUG(("+++ at c%d +++\n", (int) (css - d->ssets)));
131  co = GETCOLOR(cm, *cp);
132  FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
133  ss = css->outs[co];
134  if (ss == NULL)
135  {
136  ss = miss(v, d, css, co, cp + 1, start);
137  if (ss == NULL)
138  break; /* NOTE BREAK OUT */
139  }
140  cp++;
141  ss->lastseen = cp;
142  css = ss;
143  }
144  }
145  else
146 #endif
147  {
148  while (cp < realstop)
149  {
150  co = GETCOLOR(cm, *cp);
151  ss = css->outs[co];
152  if (ss == NULL)
153  {
154  ss = miss(v, d, css, co, cp + 1, start);
155  if (ss == NULL)
156  break; /* NOTE BREAK OUT */
157  }
158  cp++;
159  ss->lastseen = cp;
160  css = ss;
161  }
162  }
163 
164  if (ISERR())
165  return NULL;
166 
167  /* shutdown */
168  FDEBUG(("+++ shutdown at c%d +++\n", (int) (css - d->ssets)));
169  if (cp == v->stop && stop == v->stop)
170  {
171  if (hitstopp != NULL)
172  *hitstopp = 1;
173  co = d->cnfa->eos[(v->eflags & REG_NOTEOL) ? 0 : 1];
174  FDEBUG(("color %ld\n", (long) co));
175  ss = miss(v, d, css, co, cp, start);
176  if (ISERR())
177  return NULL;
178  /* special case: match ended at eol? */
179  if (ss != NULL && (ss->flags & POSTSTATE))
180  return cp;
181  else if (ss != NULL)
182  ss->lastseen = cp; /* to be tidy */
183  }
184 
185  /* find last match, if any */
186  post = d->lastpost;
187  for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
188  if ((ss->flags & POSTSTATE) && post != ss->lastseen &&
189  (post == NULL || post < ss->lastseen))
190  post = ss->lastseen;
191  if (post != NULL) /* found one */
192  return post - 1;
193 
194  return NULL;
195 }
196 
197 /*
198  * shortest - shortest-preferred matching engine
199  *
200  * On success, returns match endpoint address. Returns NULL on no match.
201  * Internal errors also return NULL, with v->err set.
202  */
203 static chr *
204 shortest(struct vars *v,
205  struct dfa *d,
206  chr *start, /* where the match should start */
207  chr *min, /* match must end at or after here */
208  chr *max, /* match must end at or before here */
209  chr **coldp, /* store coldstart pointer here, if non-NULL */
210  int *hitstopp) /* record whether hit v->stop, if non-NULL */
211 {
212  chr *cp;
213  chr *realmin = (min == v->stop) ? min : min + 1;
214  chr *realmax = (max == v->stop) ? max : max + 1;
215  color co;
216  struct sset *css;
217  struct sset *ss;
218  struct colormap *cm = d->cm;
219 
220  /* prevent "uninitialized variable" warnings */
221  if (coldp != NULL)
222  *coldp = NULL;
223  if (hitstopp != NULL)
224  *hitstopp = 0;
225 
226  /* if this is a backref to a known string, just match against that */
227  if (d->backno >= 0)
228  {
229  assert((size_t) d->backno < v->nmatch);
230  if (v->pmatch[d->backno].rm_so >= 0)
231  {
232  cp = dfa_backref(v, d, start, min, max, true);
233  if (cp != NULL && coldp != NULL)
234  *coldp = start;
235  /* there is no case where we should set *hitstopp */
236  return cp;
237  }
238  }
239 
240  /* fast path for matchall NFAs */
241  if (d->cnfa->flags & MATCHALL)
242  {
243  size_t nchr = min - start;
244 
245  if (d->cnfa->maxmatchall != DUPINF &&
246  nchr > d->cnfa->maxmatchall)
247  return NULL;
248  if ((max - start) < d->cnfa->minmatchall)
249  return NULL;
250  if (nchr < d->cnfa->minmatchall)
251  min = start + d->cnfa->minmatchall;
252  if (coldp != NULL)
253  *coldp = start;
254  /* there is no case where we should set *hitstopp */
255  return min;
256  }
257 
258  /* initialize */
259  css = initialize(v, d, start);
260  if (css == NULL)
261  return NULL;
262  cp = start;
263 
264  /* startup */
265  FDEBUG(("--- startup ---\n"));
266  if (cp == v->start)
267  {
268  co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
269  FDEBUG(("color %ld\n", (long) co));
270  }
271  else
272  {
273  co = GETCOLOR(cm, *(cp - 1));
274  FDEBUG(("char %c, color %ld\n", (char) *(cp - 1), (long) co));
275  }
276  css = miss(v, d, css, co, cp, start);
277  if (css == NULL)
278  return NULL;
279  css->lastseen = cp;
280  ss = css;
281 
282  /*
283  * This is the main text-scanning loop. It seems worth having two copies
284  * to avoid the overhead of REG_FTRACE tests here, even in REG_DEBUG
285  * builds, when you're not actively tracing.
286  */
287 #ifdef REG_DEBUG
288  if (v->eflags & REG_FTRACE)
289  {
290  while (cp < realmax)
291  {
292  FDEBUG(("--- at c%d ---\n", (int) (css - d->ssets)));
293  co = GETCOLOR(cm, *cp);
294  FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
295  ss = css->outs[co];
296  if (ss == NULL)
297  {
298  ss = miss(v, d, css, co, cp + 1, start);
299  if (ss == NULL)
300  break; /* NOTE BREAK OUT */
301  }
302  cp++;
303  ss->lastseen = cp;
304  css = ss;
305  if ((ss->flags & POSTSTATE) && cp >= realmin)
306  break; /* NOTE BREAK OUT */
307  }
308  }
309  else
310 #endif
311  {
312  while (cp < realmax)
313  {
314  co = GETCOLOR(cm, *cp);
315  ss = css->outs[co];
316  if (ss == NULL)
317  {
318  ss = miss(v, d, css, co, cp + 1, start);
319  if (ss == NULL)
320  break; /* NOTE BREAK OUT */
321  }
322  cp++;
323  ss->lastseen = cp;
324  css = ss;
325  if ((ss->flags & POSTSTATE) && cp >= realmin)
326  break; /* NOTE BREAK OUT */
327  }
328  }
329 
330  if (ss == NULL)
331  return NULL;
332 
333  if (coldp != NULL) /* report last no-progress state set, if any */
334  *coldp = lastcold(v, d);
335 
336  if ((ss->flags & POSTSTATE) && cp > min)
337  {
338  assert(cp >= realmin);
339  cp--;
340  }
341  else if (cp == v->stop && max == v->stop)
342  {
343  co = d->cnfa->eos[(v->eflags & REG_NOTEOL) ? 0 : 1];
344  FDEBUG(("color %ld\n", (long) co));
345  ss = miss(v, d, css, co, cp, start);
346  /* match might have ended at eol */
347  if ((ss == NULL || !(ss->flags & POSTSTATE)) && hitstopp != NULL)
348  *hitstopp = 1;
349  }
350 
351  if (ss == NULL || !(ss->flags & POSTSTATE))
352  return NULL;
353 
354  return cp;
355 }
356 
357 /*
358  * matchuntil - incremental matching engine
359  *
360  * This is meant for use with a search-style NFA (that is, the pattern is
361  * known to act as though it had a leading .*). We determine whether a
362  * match exists starting at v->start and ending at probe. Multiple calls
363  * require only O(N) time not O(N^2) so long as the probe values are
364  * nondecreasing. *lastcss and *lastcp must be initialized to NULL before
365  * starting a series of calls.
366  *
367  * Returns 1 if a match exists, 0 if not.
368  * Internal errors also return 0, with v->err set.
369  */
370 static int
371 matchuntil(struct vars *v,
372  struct dfa *d,
373  chr *probe, /* we want to know if a match ends here */
374  struct sset **lastcss, /* state storage across calls */
375  chr **lastcp) /* state storage across calls */
376 {
377  chr *cp = *lastcp;
378  color co;
379  struct sset *css = *lastcss;
380  struct sset *ss;
381  struct colormap *cm = d->cm;
382 
383  /* fast path for matchall NFAs */
384  if (d->cnfa->flags & MATCHALL)
385  {
386  size_t nchr = probe - v->start;
387 
388  if (nchr < d->cnfa->minmatchall)
389  return 0;
390  /* maxmatchall will always be infinity, cf. makesearch() */
391  assert(d->cnfa->maxmatchall == DUPINF);
392  return 1;
393  }
394 
395  /* initialize and startup, or restart, if necessary */
396  if (cp == NULL || cp > probe)
397  {
398  cp = v->start;
399  css = initialize(v, d, cp);
400  if (css == NULL)
401  return 0;
402 
403  FDEBUG((">>> startup >>>\n"));
404  co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
405  FDEBUG(("color %ld\n", (long) co));
406 
407  css = miss(v, d, css, co, cp, v->start);
408  if (css == NULL)
409  return 0;
410  css->lastseen = cp;
411  }
412  else if (css == NULL)
413  {
414  /* we previously found that no match is possible beyond *lastcp */
415  return 0;
416  }
417  ss = css;
418 
419  /*
420  * This is the main text-scanning loop. It seems worth having two copies
421  * to avoid the overhead of REG_FTRACE tests here, even in REG_DEBUG
422  * builds, when you're not actively tracing.
423  */
424 #ifdef REG_DEBUG
425  if (v->eflags & REG_FTRACE)
426  {
427  while (cp < probe)
428  {
429  FDEBUG((">>> at c%d >>>\n", (int) (css - d->ssets)));
430  co = GETCOLOR(cm, *cp);
431  FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
432  ss = css->outs[co];
433  if (ss == NULL)
434  {
435  ss = miss(v, d, css, co, cp + 1, v->start);
436  if (ss == NULL)
437  break; /* NOTE BREAK OUT */
438  }
439  cp++;
440  ss->lastseen = cp;
441  css = ss;
442  }
443  }
444  else
445 #endif
446  {
447  while (cp < probe)
448  {
449  co = GETCOLOR(cm, *cp);
450  ss = css->outs[co];
451  if (ss == NULL)
452  {
453  ss = miss(v, d, css, co, cp + 1, v->start);
454  if (ss == NULL)
455  break; /* NOTE BREAK OUT */
456  }
457  cp++;
458  ss->lastseen = cp;
459  css = ss;
460  }
461  }
462 
463  *lastcss = ss;
464  *lastcp = cp;
465 
466  if (ss == NULL)
467  return 0; /* impossible match, or internal error */
468 
469  /* We need to process one more chr, or the EOS symbol, to check match */
470  if (cp < v->stop)
471  {
472  FDEBUG((">>> at c%d >>>\n", (int) (css - d->ssets)));
473  co = GETCOLOR(cm, *cp);
474  FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
475  ss = css->outs[co];
476  if (ss == NULL)
477  ss = miss(v, d, css, co, cp + 1, v->start);
478  }
479  else
480  {
481  assert(cp == v->stop);
482  co = d->cnfa->eos[(v->eflags & REG_NOTEOL) ? 0 : 1];
483  FDEBUG(("color %ld\n", (long) co));
484  ss = miss(v, d, css, co, cp, v->start);
485  }
486 
487  if (ss == NULL || !(ss->flags & POSTSTATE))
488  return 0;
489 
490  return 1;
491 }
492 
493 /*
494  * dfa_backref - find best match length for a known backref string
495  *
496  * When the backref's referent is already available, we can deliver an exact
497  * answer with considerably less work than running the backref node's NFA.
498  *
499  * Return match endpoint for longest or shortest valid repeated match,
500  * or NULL if there is no valid match.
501  *
502  * Should be in sync with cbrdissect(), although that has the different task
503  * of checking a match to a predetermined section of the string.
504  */
505 static chr *
507  struct dfa *d,
508  chr *start, /* where the match should start */
509  chr *min, /* match must end at or after here */
510  chr *max, /* match must end at or before here */
511  bool shortest)
512 {
513  int n = d->backno;
514  int backmin = d->backmin;
515  int backmax = d->backmax;
516  size_t numreps;
517  size_t minreps;
518  size_t maxreps;
519  size_t brlen;
520  chr *brstring;
521  chr *p;
522 
523  /* get the backreferenced string (caller should have checked this) */
524  if (v->pmatch[n].rm_so == -1)
525  return NULL;
526  brstring = v->start + v->pmatch[n].rm_so;
527  brlen = v->pmatch[n].rm_eo - v->pmatch[n].rm_so;
528 
529  /* special-case zero-length backreference to avoid divide by zero */
530  if (brlen == 0)
531  {
532  /*
533  * matches only a zero-length string, but any number of repetitions
534  * can be considered to be present
535  */
536  if (min == start && backmin <= backmax)
537  return start;
538  return NULL;
539  }
540 
541  /*
542  * convert min and max into numbers of possible repetitions of the backref
543  * string, rounding appropriately
544  */
545  if (min <= start)
546  minreps = 0;
547  else
548  minreps = (min - start - 1) / brlen + 1;
549  maxreps = (max - start) / brlen;
550 
551  /* apply bounds, then see if there is any allowed match length */
552  if (minreps < backmin)
553  minreps = backmin;
554  if (backmax != DUPINF && maxreps > backmax)
555  maxreps = backmax;
556  if (maxreps < minreps)
557  return NULL;
558 
559  /* quick exit if zero-repetitions match is valid and preferred */
560  if (shortest && minreps == 0)
561  return start;
562 
563  /* okay, compare the actual string contents */
564  p = start;
565  numreps = 0;
566  while (numreps < maxreps)
567  {
568  if ((*v->g->compare) (brstring, p, brlen) != 0)
569  break;
570  p += brlen;
571  numreps++;
572  if (shortest && numreps >= minreps)
573  break;
574  }
575 
576  if (numreps >= minreps)
577  return p;
578  return NULL;
579 }
580 
581 /*
582  * lastcold - determine last point at which no progress had been made
583  */
584 static chr * /* endpoint, or NULL */
585 lastcold(struct vars *v,
586  struct dfa *d)
587 {
588  struct sset *ss;
589  chr *nopr;
590  int i;
591 
592  nopr = d->lastnopr;
593  if (nopr == NULL)
594  nopr = v->start;
595  for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
596  if ((ss->flags & NOPROGRESS) && nopr < ss->lastseen)
597  nopr = ss->lastseen;
598  return nopr;
599 }
600 
601 /*
602  * newdfa - set up a fresh DFA
603  *
604  * Returns NULL (and sets v->err) on failure.
605  */
606 static struct dfa *
607 newdfa(struct vars *v,
608  struct cnfa *cnfa,
609  struct colormap *cm,
610  struct smalldfa *sml) /* preallocated space, may be NULL */
611 {
612  struct dfa *d;
613  size_t nss = cnfa->nstates * 2;
614  int wordsper = (cnfa->nstates + UBITS - 1) / UBITS;
615  bool ismalloced = false;
616 
617  assert(cnfa != NULL && cnfa->nstates != 0);
618 
619  if (nss <= FEWSTATES && cnfa->ncolors <= FEWCOLORS)
620  {
621  assert(wordsper == 1);
622  if (sml == NULL)
623  {
624  sml = (struct smalldfa *) MALLOC(sizeof(struct smalldfa));
625  if (sml == NULL)
626  {
627  ERR(REG_ESPACE);
628  return NULL;
629  }
630  ismalloced = true;
631  }
632  d = &sml->dfa;
633  d->ssets = sml->ssets;
634  d->statesarea = sml->statesarea;
635  d->work = &d->statesarea[nss];
636  d->outsarea = sml->outsarea;
637  d->incarea = sml->incarea;
638  d->ismalloced = ismalloced;
639  d->arraysmalloced = false; /* not separately allocated, anyway */
640  }
641  else
642  {
643  d = (struct dfa *) MALLOC(sizeof(struct dfa));
644  if (d == NULL)
645  {
646  ERR(REG_ESPACE);
647  return NULL;
648  }
649  d->ssets = (struct sset *) MALLOC(nss * sizeof(struct sset));
650  d->statesarea = (unsigned *) MALLOC((nss + WORK) * wordsper *
651  sizeof(unsigned));
652  d->work = &d->statesarea[nss * wordsper];
653  d->outsarea = (struct sset **) MALLOC(nss * cnfa->ncolors *
654  sizeof(struct sset *));
655  d->incarea = (struct arcp *) MALLOC(nss * cnfa->ncolors *
656  sizeof(struct arcp));
657  d->ismalloced = true;
658  d->arraysmalloced = true;
659  /* now freedfa() will behave sanely */
660  if (d->ssets == NULL || d->statesarea == NULL ||
661  d->outsarea == NULL || d->incarea == NULL)
662  {
663  freedfa(d);
664  ERR(REG_ESPACE);
665  return NULL;
666  }
667  }
668 
669  d->nssets = (v->eflags & REG_SMALL) ? 7 : nss;
670  d->nssused = 0;
671  d->nstates = cnfa->nstates;
672  d->ncolors = cnfa->ncolors;
673  d->wordsper = wordsper;
674  d->cnfa = cnfa;
675  d->cm = cm;
676  d->lastpost = NULL;
677  d->lastnopr = NULL;
678  d->search = d->ssets;
679  d->backno = -1; /* may be set by caller */
680  d->backmin = d->backmax = 0;
681 
682  /* initialization of sset fields is done as needed */
683 
684  return d;
685 }
686 
687 /*
688  * freedfa - free a DFA
689  */
690 static void
691 freedfa(struct dfa *d)
692 {
693  if (d->arraysmalloced)
694  {
695  if (d->ssets != NULL)
696  FREE(d->ssets);
697  if (d->statesarea != NULL)
698  FREE(d->statesarea);
699  if (d->outsarea != NULL)
700  FREE(d->outsarea);
701  if (d->incarea != NULL)
702  FREE(d->incarea);
703  }
704 
705  if (d->ismalloced)
706  FREE(d);
707 }
708 
709 /*
710  * hash - construct a hash code for a bitvector
711  *
712  * There are probably better ways, but they're more expensive.
713  */
714 static unsigned
715 hash(unsigned *uv,
716  int n)
717 {
718  int i;
719  unsigned h;
720 
721  h = 0;
722  for (i = 0; i < n; i++)
723  h ^= uv[i];
724  return h;
725 }
726 
727 /*
728  * initialize - hand-craft a cache entry for startup, otherwise get ready
729  */
730 static struct sset *
731 initialize(struct vars *v,
732  struct dfa *d,
733  chr *start)
734 {
735  struct sset *ss;
736  int i;
737 
738  /* is previous one still there? */
739  if (d->nssused > 0 && (d->ssets[0].flags & STARTER))
740  ss = &d->ssets[0];
741  else
742  { /* no, must (re)build it */
743  ss = getvacant(v, d, start, start);
744  if (ss == NULL)
745  return NULL;
746  for (i = 0; i < d->wordsper; i++)
747  ss->states[i] = 0;
748  BSET(ss->states, d->cnfa->pre);
749  ss->hash = HASH(ss->states, d->wordsper);
750  assert(d->cnfa->pre != d->cnfa->post);
751  ss->flags = STARTER | LOCKED | NOPROGRESS;
752  /* lastseen dealt with below */
753  }
754 
755  for (i = 0; i < d->nssused; i++)
756  d->ssets[i].lastseen = NULL;
757  ss->lastseen = start; /* maybe untrue, but harmless */
758  d->lastpost = NULL;
759  d->lastnopr = NULL;
760  return ss;
761 }
762 
763 /*
764  * miss - handle a stateset cache miss
765  *
766  * css is the current stateset, co is the color of the current input character,
767  * cp points to the character after that (which is where we may need to test
768  * LACONs). start does not affect matching behavior but is needed for pickss'
769  * heuristics about which stateset cache entry to replace.
770  *
771  * Ordinarily, returns the address of the next stateset (the one that is
772  * valid after consuming the input character). Returns NULL if no valid
773  * NFA states remain, ie we have a certain match failure.
774  * Internal errors also return NULL, with v->err set.
775  */
776 static struct sset *
777 miss(struct vars *v,
778  struct dfa *d,
779  struct sset *css,
780  color co,
781  chr *cp, /* next chr */
782  chr *start) /* where the attempt got started */
783 {
784  struct cnfa *cnfa = d->cnfa;
785  int i;
786  unsigned h;
787  struct carc *ca;
788  struct sset *p;
789  int ispseudocolor;
790  int ispost;
791  int noprogress;
792  int gotstate;
793  int dolacons;
794  int sawlacons;
795 
796  /* for convenience, we can be called even if it might not be a miss */
797  if (css->outs[co] != NULL)
798  {
799  FDEBUG(("hit\n"));
800  return css->outs[co];
801  }
802  FDEBUG(("miss\n"));
803 
804  /*
805  * Checking for operation cancel in the inner text search loop seems
806  * unduly expensive. As a compromise, check during cache misses.
807  */
808  if (CANCEL_REQUESTED(v->re))
809  {
810  ERR(REG_CANCEL);
811  return NULL;
812  }
813 
814  /*
815  * What set of states would we end up in after consuming the co character?
816  * We first consider PLAIN arcs that consume the character, and then look
817  * to see what LACON arcs could be traversed after consuming it.
818  */
819  for (i = 0; i < d->wordsper; i++)
820  d->work[i] = 0; /* build new stateset bitmap in d->work */
821  ispseudocolor = d->cm->cd[co].flags & PSEUDO;
822  ispost = 0;
823  noprogress = 1;
824  gotstate = 0;
825  for (i = 0; i < d->nstates; i++)
826  if (ISBSET(css->states, i))
827  for (ca = cnfa->states[i]; ca->co != COLORLESS; ca++)
828  if (ca->co == co ||
829  (ca->co == RAINBOW && !ispseudocolor))
830  {
831  BSET(d->work, ca->to);
832  gotstate = 1;
833  if (ca->to == cnfa->post)
834  ispost = 1;
835  if (!(cnfa->stflags[ca->to] & CNFA_NOPROGRESS))
836  noprogress = 0;
837  FDEBUG(("%d -> %d\n", i, ca->to));
838  }
839  if (!gotstate)
840  return NULL; /* character cannot reach any new state */
841  dolacons = (cnfa->flags & HASLACONS);
842  sawlacons = 0;
843  /* outer loop handles transitive closure of reachable-by-LACON states */
844  while (dolacons)
845  {
846  dolacons = 0;
847  for (i = 0; i < d->nstates; i++)
848  if (ISBSET(d->work, i))
849  for (ca = cnfa->states[i]; ca->co != COLORLESS; ca++)
850  {
851  if (ca->co < cnfa->ncolors)
852  continue; /* not a LACON arc */
853  if (ISBSET(d->work, ca->to))
854  continue; /* arc would be a no-op anyway */
855  sawlacons = 1; /* this LACON affects our result */
856  if (!lacon(v, cnfa, cp, ca->co))
857  {
858  if (ISERR())
859  return NULL;
860  continue; /* LACON arc cannot be traversed */
861  }
862  if (ISERR())
863  return NULL;
864  BSET(d->work, ca->to);
865  dolacons = 1;
866  if (ca->to == cnfa->post)
867  ispost = 1;
868  if (!(cnfa->stflags[ca->to] & CNFA_NOPROGRESS))
869  noprogress = 0;
870  FDEBUG(("%d :> %d\n", i, ca->to));
871  }
872  }
873  h = HASH(d->work, d->wordsper);
874 
875  /* Is this stateset already in the cache? */
876  for (p = d->ssets, i = d->nssused; i > 0; p++, i--)
877  if (HIT(h, d->work, p, d->wordsper))
878  {
879  FDEBUG(("cached c%d\n", (int) (p - d->ssets)));
880  break; /* NOTE BREAK OUT */
881  }
882  if (i == 0)
883  { /* nope, need a new cache entry */
884  p = getvacant(v, d, cp, start);
885  if (p == NULL)
886  return NULL;
887  assert(p != css);
888  for (i = 0; i < d->wordsper; i++)
889  p->states[i] = d->work[i];
890  p->hash = h;
891  p->flags = (ispost) ? POSTSTATE : 0;
892  if (noprogress)
893  p->flags |= NOPROGRESS;
894  /* lastseen to be dealt with by caller */
895  }
896 
897  /*
898  * Link new stateset to old, unless a LACON affected the result, in which
899  * case we don't create the link. That forces future transitions across
900  * this same arc (same prior stateset and character color) to come through
901  * miss() again, so that we can recheck the LACON(s), which might or might
902  * not pass since context will be different.
903  */
904  if (!sawlacons)
905  {
906  FDEBUG(("c%d[%d]->c%d\n",
907  (int) (css - d->ssets), co, (int) (p - d->ssets)));
908  css->outs[co] = p;
909  css->inchain[co] = p->ins;
910  p->ins.ss = css;
911  p->ins.co = co;
912  }
913  return p;
914 }
915 
916 /*
917  * lacon - lookaround-constraint checker for miss()
918  */
919 static int /* predicate: constraint satisfied? */
920 lacon(struct vars *v,
921  struct cnfa *pcnfa, /* parent cnfa */
922  chr *cp,
923  color co) /* "color" of the lookaround constraint */
924 {
925  int n;
926  struct subre *sub;
927  struct dfa *d;
928  chr *end;
929  int satisfied;
930 
931  /* Since this is recursive, it could be driven to stack overflow */
932  if (STACK_TOO_DEEP(v->re))
933  {
934  ERR(REG_ETOOBIG);
935  return 0;
936  }
937 
938  n = co - pcnfa->ncolors;
939  assert(n > 0 && n < v->g->nlacons && v->g->lacons != NULL);
940  FDEBUG(("=== testing lacon %d\n", n));
941  sub = &v->g->lacons[n];
942  d = getladfa(v, n);
943  if (d == NULL)
944  return 0;
945  if (LATYPE_IS_AHEAD(sub->latype))
946  {
947  /* used to use longest() here, but shortest() could be much cheaper */
948  end = shortest(v, d, cp, cp, v->stop,
949  (chr **) NULL, (int *) NULL);
950  satisfied = LATYPE_IS_POS(sub->latype) ? (end != NULL) : (end == NULL);
951  }
952  else
953  {
954  /*
955  * To avoid doing O(N^2) work when repeatedly testing a lookbehind
956  * constraint in an N-character string, we use matchuntil() which can
957  * cache the DFA state across calls. We only need to restart if the
958  * probe point decreases, which is not common. The NFA we're using is
959  * a search NFA, so it doesn't mind scanning over stuff before the
960  * nominal match.
961  */
962  satisfied = matchuntil(v, d, cp, &v->lblastcss[n], &v->lblastcp[n]);
963  if (!LATYPE_IS_POS(sub->latype))
964  satisfied = !satisfied;
965  }
966  FDEBUG(("=== lacon %d satisfied %d\n", n, satisfied));
967  return satisfied;
968 }
969 
970 /*
971  * getvacant - get a vacant state set
972  *
973  * This routine clears out the inarcs and outarcs, but does not otherwise
974  * clear the innards of the state set -- that's up to the caller.
975  */
976 static struct sset *
977 getvacant(struct vars *v,
978  struct dfa *d,
979  chr *cp,
980  chr *start)
981 {
982  int i;
983  struct sset *ss;
984  struct sset *p;
985  struct arcp ap;
986  color co;
987 
988  ss = pickss(v, d, cp, start);
989  if (ss == NULL)
990  return NULL;
991  assert(!(ss->flags & LOCKED));
992 
993  /* clear out its inarcs, including self-referential ones */
994  ap = ss->ins;
995  while ((p = ap.ss) != NULL)
996  {
997  co = ap.co;
998  FDEBUG(("zapping c%d's %ld outarc\n", (int) (p - d->ssets), (long) co));
999  p->outs[co] = NULL;
1000  ap = p->inchain[co];
1001  p->inchain[co].ss = NULL; /* paranoia */
1002  }
1003  ss->ins.ss = NULL;
1004 
1005  /* take it off the inarc chains of the ssets reached by its outarcs */
1006  for (i = 0; i < d->ncolors; i++)
1007  {
1008  p = ss->outs[i];
1009  assert(p != ss); /* not self-referential */
1010  if (p == NULL)
1011  continue; /* NOTE CONTINUE */
1012  FDEBUG(("del outarc %d from c%d's in chn\n", i, (int) (p - d->ssets)));
1013  if (p->ins.ss == ss && p->ins.co == i)
1014  p->ins = ss->inchain[i];
1015  else
1016  {
1017  struct arcp lastap = {NULL, 0};
1018 
1019  assert(p->ins.ss != NULL);
1020  for (ap = p->ins; ap.ss != NULL &&
1021  !(ap.ss == ss && ap.co == i);
1022  ap = ap.ss->inchain[ap.co])
1023  lastap = ap;
1024  assert(ap.ss != NULL);
1025  lastap.ss->inchain[lastap.co] = ss->inchain[i];
1026  }
1027  ss->outs[i] = NULL;
1028  ss->inchain[i].ss = NULL;
1029  }
1030 
1031  /* if ss was a success state, may need to remember location */
1032  if ((ss->flags & POSTSTATE) && ss->lastseen != d->lastpost &&
1033  (d->lastpost == NULL || d->lastpost < ss->lastseen))
1034  d->lastpost = ss->lastseen;
1035 
1036  /* likewise for a no-progress state */
1037  if ((ss->flags & NOPROGRESS) && ss->lastseen != d->lastnopr &&
1038  (d->lastnopr == NULL || d->lastnopr < ss->lastseen))
1039  d->lastnopr = ss->lastseen;
1040 
1041  return ss;
1042 }
1043 
1044 /*
1045  * pickss - pick the next stateset to be used
1046  */
1047 static struct sset *
1048 pickss(struct vars *v,
1049  struct dfa *d,
1050  chr *cp,
1051  chr *start)
1052 {
1053  int i;
1054  struct sset *ss;
1055  struct sset *end;
1056  chr *ancient;
1057 
1058  /* shortcut for cases where cache isn't full */
1059  if (d->nssused < d->nssets)
1060  {
1061  i = d->nssused;
1062  d->nssused++;
1063  ss = &d->ssets[i];
1064  FDEBUG(("new c%d\n", i));
1065  /* set up innards */
1066  ss->states = &d->statesarea[i * d->wordsper];
1067  ss->flags = 0;
1068  ss->ins.ss = NULL;
1069  ss->ins.co = WHITE; /* give it some value */
1070  ss->outs = &d->outsarea[i * d->ncolors];
1071  ss->inchain = &d->incarea[i * d->ncolors];
1072  for (i = 0; i < d->ncolors; i++)
1073  {
1074  ss->outs[i] = NULL;
1075  ss->inchain[i].ss = NULL;
1076  }
1077  return ss;
1078  }
1079 
1080  /* look for oldest, or old enough anyway */
1081  if (cp - start > d->nssets * 2 / 3) /* oldest 33% are expendable */
1082  ancient = cp - d->nssets * 2 / 3;
1083  else
1084  ancient = start;
1085  for (ss = d->search, end = &d->ssets[d->nssets]; ss < end; ss++)
1086  if ((ss->lastseen == NULL || ss->lastseen < ancient) &&
1087  !(ss->flags & LOCKED))
1088  {
1089  d->search = ss + 1;
1090  FDEBUG(("replacing c%d\n", (int) (ss - d->ssets)));
1091  return ss;
1092  }
1093  for (ss = d->ssets, end = d->search; ss < end; ss++)
1094  if ((ss->lastseen == NULL || ss->lastseen < ancient) &&
1095  !(ss->flags & LOCKED))
1096  {
1097  d->search = ss + 1;
1098  FDEBUG(("replacing c%d\n", (int) (ss - d->ssets)));
1099  return ss;
1100  }
1101 
1102  /* nobody's old enough?!? -- something's really wrong */
1103  FDEBUG(("cannot find victim to replace!\n"));
1104  ERR(REG_ASSERT);
1105  return NULL;
1106 }
struct sset * ssets
Definition: regexec.c:70
#define STARTER
Definition: regexec.c:53
#define LATYPE_IS_POS(la)
Definition: regguts.h:103
static int matchuntil(struct vars *v, struct dfa *d, chr *probe, struct sset **lastcss, chr **lastcp)
Definition: rege_dfa.c:371
chr * lastseen
Definition: regexec.c:58
#define REG_NOTBOL
Definition: regex.h:126
struct sset ** outs
Definition: regexec.c:59
#define ERR
Definition: _int.h:161
short backmin
Definition: regexec.c:81
struct arcp * incarea
Definition: regexec.c:74
int maxmatchall
Definition: regguts.h:419
struct subre * lacons
Definition: regguts.h:539
struct colormap * cm
Definition: regexec.c:76
#define CNFA_NOPROGRESS
Definition: regguts.h:413
#define REG_ESPACE
Definition: regex.h:151
struct cnfa * cnfa
Definition: regexec.c:75
#define RAINBOW
Definition: regguts.h:154
regoff_t rm_so
Definition: regex.h:87
Definition: regguts.h:401
short color
Definition: regguts.h:150
static chr * dfa_backref(struct vars *v, struct dfa *d, chr *start, chr *min, chr *max, bool shortest)
Definition: rege_dfa.c:506
int pre
Definition: regguts.h:408
#define WORK
Definition: regexec.c:87
static struct sset * pickss(struct vars *v, struct dfa *d, chr *cp, chr *start)
Definition: rege_dfa.c:1048
#define REG_FTRACE
Definition: regex.h:129
unsigned * work
Definition: regexec.c:72
#define FREE(ptr)
Definition: cryptohash.c:37
struct sset * search
Definition: regexec.c:79
static void freedfa(struct dfa *d)
Definition: rege_dfa.c:691
#define ISERR()
Definition: regcomp.c:273
static struct sset * initialize(struct vars *v, struct dfa *d, chr *start)
Definition: rege_dfa.c:731
char latype
Definition: regguts.h:490
#define FEWCOLORS
Definition: regexec.c:91
struct carc ** states
Definition: regguts.h:414
struct colordesc * cd
Definition: regguts.h:231
#define HIT(h, bv, ss, nw)
Definition: regexec.c:50
chr * start
Definition: regexec.c:114
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Definition: regex.h:88
#define MALLOC(n)
Definition: regcustom.h:60
Definition: regexec.c:63
struct sset ** lblastcss
Definition: regexec.c:120
static struct sset * getvacant(struct vars *v, struct dfa *d, chr *cp, chr *start)
Definition: rege_dfa.c:977
int nstates
Definition: regguts.h:403
static struct dfa * newdfa(struct vars *v, struct cnfa *cnfa, struct colormap *cm, struct smalldfa *sml)
Definition: rege_dfa.c:607
#define HASH(sign, val, siglen)
Definition: hstore_gist.c:45
pg_wchar chr
Definition: regcustom.h:66
unsigned statesarea[FEWSTATES *2+WORK]
Definition: regexec.c:96
unsigned * states
Definition: regexec.c:47
static chr * lastcold(struct vars *v, struct dfa *d)
Definition: rege_dfa.c:585
bool ismalloced
Definition: regexec.c:83
regex_t * re
Definition: regcomp.c:239
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Definition: regexec.c:60
struct dfa dfa
Definition: regexec.c:94
#define NOPROGRESS
Definition: regexec.c:56
bool arraysmalloced
Definition: regexec.c:84
#define assert(TEST)
Definition: imath.c:73
int ncolors
Definition: regexec.c:68
#define LATYPE_IS_AHEAD(la)
Definition: regguts.h:104
char * stflags
Definition: regguts.h:412
int nstates
Definition: regexec.c:67
int nssets
Definition: regexec.c:65
int nssused
Definition: regexec.c:66
int wordsper
Definition: regexec.c:69
struct guts * g
Definition: regexec.c:109
#define MATCHALL
Definition: regguts.h:407
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Definition: regexec.c:110
#define UBITS
Definition: regguts.h:125
color bos[2]
Definition: regguts.h:410
struct arcp incarea[FEWSTATES *2 *FEWCOLORS]
Definition: regexec.c:98
chr * lastnopr
Definition: regexec.c:78
#define REG_SMALL
Definition: regex.h:131
#define FDEBUG(arglist)
Definition: regguts.h:116
static struct sset * miss(struct vars *v, struct dfa *d, struct sset *css, color co, chr *cp, chr *start)
Definition: rege_dfa.c:777
static chr * shortest(struct vars *v, struct dfa *d, chr *start, chr *min, chr *max, chr **coldp, int *hitstopp)
Definition: rege_dfa.c:204
Definition: regexec.c:39
int to
Definition: regguts.h:398
struct sset ssets[FEWSTATES *2]
Definition: regexec.c:95
#define DUPINF
Definition: regguts.h:94
#define REG_ASSERT
Definition: regex.h:153
#define ISBSET(uv, sn)
Definition: regguts.h:127
int backno
Definition: regexec.c:80
int flags
Definition: regguts.h:179
regmatch_t * pmatch
Definition: regexec.c:112
int flags
Definition: regguts.h:405
short backmax
Definition: regexec.c:82
struct sset * outsarea[FEWSTATES *2 *FEWCOLORS]
Definition: regexec.c:97
#define POSTSTATE
Definition: regexec.c:54
#define REG_ETOOBIG
Definition: regex.h:157
#define WHITE
Definition: regguts.h:155
int minmatchall
Definition: regguts.h:418
static chr * longest(struct vars *v, struct dfa *d, chr *start, chr *stop, int *hitstopp)
Definition: rege_dfa.c:42
Definition: regguts.h:471
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Definition: regexec.c:111
struct arcp ins
Definition: regexec.c:57
int post
Definition: regguts.h:409
const chr * stop
Definition: regcomp.c:241
struct vars * v
Definition: regguts.h:227
#define BSET(uv, sn)
Definition: regguts.h:126
struct sset ** outsarea
Definition: regexec.c:73
#define PSEUDO
Definition: regguts.h:181
#define LOCKED
Definition: regexec.c:55
color co
Definition: regguts.h:397
Definition: regexec.c:45
#define CANCEL_REQUESTED(re)
Definition: regguts.h:517
int i
#define COLORLESS
Definition: regguts.h:153
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Definition: regexec.c:77
chr ** lblastcp
Definition: regexec.c:121
static int lacon(struct vars *v, struct cnfa *pcnfa, chr *cp, color co)
Definition: rege_dfa.c:920
unsigned hash
Definition: regexec.c:48
struct sset * ss
Definition: regexec.c:41
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Definition: regexec.c:71
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Definition: regexec.c:391
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Definition: regexec.c:52
Definition: regcomp.c:237
static unsigned hash(unsigned *uv, int n)
Definition: rege_dfa.c:715
#define HASLACONS
Definition: regguts.h:406
#define REG_NOTEOL
Definition: regex.h:127
#define GETCOLOR(cm, c)
Definition: regguts.h:252
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Definition: regguts.h:229
#define STACK_TOO_DEEP(re)
Definition: regguts.h:520
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Definition: regguts.h:411
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Definition: regguts.h:404
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Definition: regexec.c:42
#define REG_CANCEL
Definition: regex.h:159
Definition: regguts.h:395