summaryrefslogtreecommitdiffstats
path: root/generic/regexec.c
blob: 94243854cad1cddf234b2dc7e311594f5c300346 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
/*
 * re_*exec and friends - match REs
 *
 * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
 * 
 * Development of this software was funded, in part, by Cray Research Inc.,
 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
 * Corporation, none of whom are responsible for the results.  The author
 * thanks all of them. 
 * 
 * Redistribution and use in source and binary forms -- with or without
 * modification -- are permitted for any purpose, provided that
 * redistributions in source form retain this entire copyright notice and
 * indicate the origin and nature of any modifications.
 * 
 * I'd appreciate being given credit for this package in the documentation
 * of software which uses it, but that is not a requirement.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "regguts.h"



/* internal variables, bundled for easy passing around */
struct vars {
	regex_t *re;
	struct guts *g;
	int eflags;		/* copies of arguments */
	size_t nmatch;
	regmatch_t *pmatch;
	rm_detail_t *details;
	chr *start;		/* start of string */
	chr *stop;		/* just past end of string */
	int err;		/* error code if any (0 none) */
	regoff_t *mem;		/* memory vector for backtracking */
};
#define	VISERR(vv)	((vv)->err != 0)	/* have we seen an error yet? */
#define	ISERR()	VISERR(v)
#define	VERR(vv,e)	(((vv)->err) ? (vv)->err : ((vv)->err = (e)))
#define	ERR(e)	VERR(v, e)		/* record an error */
#define	NOERR()	{if (ISERR()) return;}	/* if error seen, return */
#define	OFF(p)	((p) - v->start)
#define	LOFF(p)	((long)OFF(p))



/* lazy-DFA representation */
struct arcp {			/* "pointer" to an outarc */
	struct sset *ss;
	color co;
};

struct sset {			/* state set */
	unsigned *states;	/* pointer to bitvector */
	unsigned hash;		/* hash of bitvector */
#		define	HASH(bv, nw)	(((nw) == 1) ? *(bv) : hash(bv, nw))
#	define	HIT(h,bv,ss,nw)	((ss)->hash == (h) && ((nw) == 1 || \
		memcmp(VS(bv), VS((ss)->states), (nw)*sizeof(unsigned)) == 0))
	int flags;
#		define	STARTER		01	/* the initial state set */
#		define	POSTSTATE	02	/* includes the goal state */
#		define	LOCKED		04	/* locked in cache */
#		define	NOPROGRESS	010	/* zero-progress state set */
	struct arcp ins;	/* chain of inarcs pointing here */
	chr *lastseen;		/* last entered on arrival here */
	struct sset **outs;	/* outarc vector indexed by color */
	struct arcp *inchain;	/* chain-pointer vector for outarcs */
};

struct dfa {
	int nssets;		/* size of cache */
	int nssused;		/* how many entries occupied yet */
	int nstates;		/* number of states */
	int ncolors;		/* length of outarc and inchain vectors */
	int wordsper;		/* length of state-set bitvectors */
	struct sset *ssets;	/* state-set cache */
	unsigned *statesarea;	/* bitvector storage */
	unsigned *work;		/* pointer to work area within statesarea */
	struct sset **outsarea;	/* outarc-vector storage */
	struct arcp *incarea;	/* inchain storage */
	struct cnfa *cnfa;
	struct colormap *cm;
	chr *lastpost;		/* location of last cache-flushed success */
	chr *lastnopr;		/* location of last cache-flushed NOPROGRESS */
	struct sset *search;	/* replacement-search-pointer memory */
	int cptsmalloced;	/* were the areas individually malloced? */
	char *mallocarea;	/* self, or master malloced area, or NULL */
};

#define	WORK	1		/* number of work bitvectors needed */

/* setup for non-malloc allocation for small cases */
#define	FEWSTATES	20	/* must be less than UBITS */
#define	FEWCOLORS	15
struct smalldfa {
	struct dfa dfa;
	struct sset ssets[FEWSTATES*2];
	unsigned statesarea[FEWSTATES*2 + WORK];
	struct sset *outsarea[FEWSTATES*2 * FEWCOLORS];
	struct arcp incarea[FEWSTATES*2 * FEWCOLORS];
};




/*
 * forward declarations
 */
/* =====^!^===== begin forwards =====^!^===== */
/* automatically gathered by fwd; do not hand-edit */
/* === regexec.c === */
int exec _ANSI_ARGS_((regex_t *, CONST chr *, size_t, rm_detail_t *, size_t, regmatch_t [], int));
static int find _ANSI_ARGS_((struct vars *, struct cnfa *, struct colormap *));
static int cfind _ANSI_ARGS_((struct vars *, struct cnfa *, struct colormap *));
static VOID zapsubs _ANSI_ARGS_((regmatch_t *, size_t));
static VOID zapmem _ANSI_ARGS_((struct vars *, struct subre *));
static VOID subset _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int dissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int condissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int altdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int cdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int ccondissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int crevdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int cbrdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
static int caltdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));
/* === rege_dfa.c === */
static chr *longest _ANSI_ARGS_((struct vars *, struct dfa *, chr *, chr *, int *));
static chr *shortest _ANSI_ARGS_((struct vars *, struct dfa *, chr *, chr *, chr *, chr **, int *));
static chr *lastcold _ANSI_ARGS_((struct vars *, struct dfa *));
static struct dfa *newdfa _ANSI_ARGS_((struct vars *, struct cnfa *, struct colormap *, struct smalldfa *));
static VOID freedfa _ANSI_ARGS_((struct dfa *));
static unsigned hash _ANSI_ARGS_((unsigned *, int));
static struct sset *initialize _ANSI_ARGS_((struct vars *, struct dfa *, chr *));
static struct sset *miss _ANSI_ARGS_((struct vars *, struct dfa *, struct sset *, pcolor, chr *, chr *));
static int lacon _ANSI_ARGS_((struct vars *, struct cnfa *, chr *, pcolor));
static struct sset *getvacant _ANSI_ARGS_((struct vars *, struct dfa *, chr *, chr *));
static struct sset *pickss _ANSI_ARGS_((struct vars *, struct dfa *, chr *, chr *));
/* automatically gathered by fwd; do not hand-edit */
/* =====^!^===== end forwards =====^!^===== */



/*
 - exec - match regular expression
 ^ int exec(regex_t *, CONST chr *, size_t, rm_detail_t *,
 ^					size_t, regmatch_t [], int);
 */
int
exec(re, string, len, details, nmatch, pmatch, flags)
regex_t *re;
CONST chr *string;
size_t len;
rm_detail_t *details;
size_t nmatch;
regmatch_t pmatch[];
int flags;
{
	struct vars var;
	register struct vars *v = &var;
	int st;
	size_t n;
	int complications;
#	define	LOCALMAT	20
	regmatch_t mat[LOCALMAT];
#	define	LOCALMEM	40
	regoff_t mem[LOCALMEM];

	/* sanity checks */
	if (re == NULL || string == NULL || re->re_magic != REMAGIC)
		return REG_INVARG;
	if (re->re_csize != sizeof(chr))
		return REG_MIXED;

	/* setup */
	v->re = re;
	v->g = (struct guts *)re->re_guts;
	if ((v->g->cflags&REG_EXPECT) && details == NULL)
		return REG_INVARG;
	if (v->g->unmatchable)
		return REG_NOMATCH;
	complications = (v->g->info&REG_UBACKREF) ? 1 : 0;
	if (v->g->usedshorter)
		complications = 1;
	v->eflags = flags;
	if (v->g->cflags&REG_NOSUB)
		nmatch = 0;		/* override client */
	v->nmatch = nmatch;
	if (complications && v->nmatch < v->g->nsub + 1) {
		/* need work area bigger than what user gave us */
		if (v->g->nsub + 1 <= LOCALMAT)
			v->pmatch = mat;
		else
			v->pmatch = (regmatch_t *)MALLOC((v->g->nsub + 1) *
							sizeof(regmatch_t));
		if (v->pmatch == NULL)
			return REG_ESPACE;
		v->nmatch = v->g->nsub + 1;
	} else
		v->pmatch = pmatch;
	v->details = details;
	v->start = (chr *)string;
	v->stop = (chr *)string + len;
	v->err = 0;
	if (complications) {
		assert(v->g->ntree >= 0);
		n = (size_t)v->g->ntree;
		if (n <= LOCALMEM)
			v->mem = mem;
		else
			v->mem = (regoff_t *)MALLOC(n*sizeof(regoff_t));
		if (v->mem == NULL) {
			if (v->pmatch != pmatch && v->pmatch != mat)
				FREE(v->pmatch);
			return REG_ESPACE;
		}
	} else
		v->mem = NULL;

	/* do it */
	assert(v->g->tree != NULL);
	if (complications)
		st = cfind(v, &v->g->tree->cnfa, &v->g->cmap);
	else
		st = find(v, &v->g->tree->cnfa, &v->g->cmap);

	/* copy (portion of) match vector over if necessary */
	if (st == REG_OKAY && v->pmatch != pmatch && nmatch > 0) {
		zapsubs(pmatch, nmatch);
		n = (nmatch < v->nmatch) ? nmatch : v->nmatch;
		memcpy(VS(pmatch), VS(v->pmatch), n*sizeof(regmatch_t));
	}

	/* clean up */
	if (v->pmatch != pmatch && v->pmatch != mat)
		FREE(v->pmatch);
	if (v->mem != NULL && v->mem != mem)
		FREE(v->mem);
	return st;
}

/*
 - find - find a match for the main NFA (no-complications case)
 ^ static int find(struct vars *, struct cnfa *, struct colormap *);
 */
static int
find(v, cnfa, cm)
struct vars *v;
struct cnfa *cnfa;
struct colormap *cm;
{
	struct smalldfa da;
	struct dfa *d = newdfa(v, cnfa, cm, &da);
	struct smalldfa sa;
	struct dfa *s = newdfa(v, &v->g->search, cm, &sa);
	chr *begin;
	chr *end;
	chr *cold;
	chr *open;		/* open and close of range of possible starts */
	chr *close;
	int hitend;

	if (ISERR()) {		/* should be newdfa() failure */
		if (d != NULL)
			freedfa(d);
		if (s != NULL)
			freedfa(s);
		return v->err;
	}

	/* first, a shot with the search RE */
	MDEBUG(("\nsearch at %ld\n", LOFF(v->start)));
	cold = NULL;
	close = shortest(v, s, v->start, v->start, v->stop, &cold, (int *)NULL);
	freedfa(s);
	if (v->g->cflags&REG_EXPECT) {
		assert(v->details != NULL);
		if (cold != NULL)
			v->details->rm_extend.rm_so = OFF(cold);
		else
			v->details->rm_extend.rm_so = OFF(v->stop);
		v->details->rm_extend.rm_eo = OFF(v->stop);	/* unknown */
	}
	if (close == NULL) {		/* not found */
		freedfa(d);
		if (ISERR())
			return v->err;
		return REG_NOMATCH;
	}
	if (v->nmatch == 0) {		/* found, don't need exact location */
		freedfa(d);
		return REG_OKAY;
	}

	/* find starting point */
	assert(cold != NULL);
	open = cold;
	cold = NULL;
	MDEBUG(("between %ld and %ld\n", LOFF(open), LOFF(close)));
	for (begin = open; begin <= close; begin++) {
		MDEBUG(("\nfind trying at %ld\n", LOFF(begin)));
		end = longest(v, d, begin, v->stop, &hitend);
		if (hitend && cold == NULL)
			cold = begin;
		if (end != NULL)
			break;		/* NOTE BREAK OUT */
	}
	assert(end != NULL);		/* search RE succeeded so loop should */
	freedfa(d);

	/* and pin down details */
	assert(v->nmatch > 0);
	v->pmatch[0].rm_so = OFF(begin);
	v->pmatch[0].rm_eo = OFF(end);
	if (v->g->cflags&REG_EXPECT) {
		if (cold != NULL)
			v->details->rm_extend.rm_so = OFF(cold);
		else
			v->details->rm_extend.rm_eo = OFF(v->stop);
		v->details->rm_extend.rm_eo = OFF(v->stop);	/* unknown */
	}
	if (v->nmatch > 1) {
		zapsubs(v->pmatch, v->nmatch);
		return dissect(v, v->g->tree, begin, end);
	}
	if (ISERR())
		return v->err;
	return REG_OKAY;
}

/*
 - cfind - find a match for the main NFA (with complications)
 ^ static int cfind(struct vars *, struct cnfa *, struct colormap *);
 */
static int
cfind(v, cnfa, cm)
struct vars *v;
struct cnfa *cnfa;
struct colormap *cm;
{
	struct smalldfa da;
	struct dfa *d = newdfa(v, cnfa, cm, &da);
	struct smalldfa sa;
	struct dfa *s = newdfa(v, &v->g->search, cm, &sa);
	chr *begin;
	chr *end;
	chr *cold;
	chr *open;		/* open and close of range of possible starts */
	chr *close;
	chr *estart;
	chr *estop;
	int er;
	int shorter = v->g->tree->flags&SHORTER;
	int ret = REG_NOMATCH;
	int hitend;

	if (d == NULL)
		return v->err;
	if (s == NULL) {
		freedfa(d);
		return v->err;
	}

	cold = NULL;
	close = v->start;
	do {
		MDEBUG(("\ncsearch at %ld\n", LOFF(close)));
		close = shortest(v, s, close, close, v->stop, &cold, (int *)NULL);
		if (close == NULL)
			break;				/* NOTE BREAK */
		assert(cold != NULL);
		open = cold;
		cold = NULL;
		MDEBUG(("cbetween %ld and %ld\n", LOFF(open), LOFF(close)));
		for (begin = open; begin <= close; begin++) {
			MDEBUG(("\ncfind trying at %ld\n", LOFF(begin)));
			estart = begin;
			estop = v->stop;
			for (;;) {
				if (shorter)
					end = shortest(v, d, begin, estart,
						estop, (chr **)NULL, &hitend);
				else
					end = longest(v, d, begin, estop,
								&hitend);
				if (hitend && cold == NULL)
					cold = begin;
				if (end == NULL)
					break;		/* NOTE BREAK OUT */
				MDEBUG(("tentative end %ld\n", LOFF(end)));
				zapsubs(v->pmatch, v->nmatch);
				zapmem(v, v->g->tree);
				er = cdissect(v, v->g->tree, begin, end);
				if (er == REG_OKAY) {
					if (v->nmatch > 0) {
						v->pmatch[0].rm_so = OFF(begin);
						v->pmatch[0].rm_eo = OFF(end);
					}
					ret = REG_OKAY;
					break;		/* NOTE BREAK OUT */
				}
				if (er != REG_NOMATCH) {
					ERR(er);
					break;		/* NOTE BREAK OUT */
				}
				if ((shorter) ? end == estop : end == begin) {
					/* no point in trying again */
					break;		/* NOTE BREAK OUT */
				}
				/* go around and try again */
				if (shorter)
					estart = end + 1;
				else
					estop = end - 1;
			}
		}
	} while (close < v->stop);

	freedfa(d);
	freedfa(s);
	if (ISERR())
		return v->err;
	if (v->g->cflags&REG_EXPECT) {
		assert(v->details != NULL);
		if (cold != NULL)
			v->details->rm_extend.rm_so = OFF(cold);
		else
			v->details->rm_extend.rm_so = OFF(v->stop);
		v->details->rm_extend.rm_eo = OFF(v->stop);	/* unknown */
	}
	return ret;
}

/*
 - zapsubs - initialize the subexpression matches to "no match"
 ^ static VOID zapsubs(regmatch_t *, size_t);
 */
static VOID
zapsubs(p, n)
regmatch_t *p;
size_t n;
{
	size_t i;

	for (i = n-1; i > 0; i--) {
		p[i].rm_so = -1;
		p[i].rm_eo = -1;
	}
}

/*
 - zapmem - initialize the retry memory of a subtree to zeros
 ^ static VOID zapmem(struct vars *, struct subre *);
 */
static VOID
zapmem(v, t)
struct vars *v;
struct subre *t;
{
	if (t == NULL)
		return;

	assert(v->mem != NULL);
	v->mem[t->retry] = 0;
	if (t->op == '(') {
		assert(t->subno > 0);
		v->pmatch[t->subno].rm_so = -1;
		v->pmatch[t->subno].rm_eo = -1;
	}

	if (t->left != NULL)
		zapmem(v, t->left);
	if (t->right != NULL)
		zapmem(v, t->right);
}

/*
 - subset - set any subexpression relevant to a successful subre
 ^ static VOID subset(struct vars *, struct subre *, chr *, chr *);
 */
static VOID
subset(v, sub, begin, end)
struct vars *v;
struct subre *sub;
chr *begin;
chr *end;
{
	int n = sub->subno;

	assert(n > 0);
	if ((size_t)n >= v->nmatch)
		return;

	MDEBUG(("setting %d\n", n));
	v->pmatch[n].rm_so = OFF(begin);
	v->pmatch[n].rm_eo = OFF(end);
}

/*
 - dissect - determine subexpression matches (uncomplicated case)
 ^ static int dissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
dissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	assert(t != NULL);
	MDEBUG(("dissect %ld-%ld\n", LOFF(begin), LOFF(end)));

	switch (t->op) {
	case '=':		/* terminal node */
		assert(t->left == NULL && t->right == NULL);
		return REG_OKAY;	/* no action, parent did the work */
		break;
	case '|':		/* alternation */
		assert(t->left != NULL);
		return altdissect(v, t, begin, end);
		break;
	case 'b':		/* back ref -- shouldn't be calling us! */
		return REG_ASSERT;
		break;
	case '.':		/* concatenation */
		assert(t->left != NULL && t->right != NULL);
		return condissect(v, t, begin, end);
		break;
	case '(':		/* capturing */
		assert(t->left != NULL && t->right == NULL);
		assert(t->subno > 0);
		subset(v, t, begin, end);
		return dissect(v, t->left, begin, end);
		break;
	default:
		return REG_ASSERT;
		break;
	}
}

/*
 - condissect - determine concatenation subexpression matches (uncomplicated)
 ^ static int condissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
condissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	struct smalldfa da;
	struct dfa *d;
	struct smalldfa d2a;
	struct dfa *d2;
	chr *mid;
	int i;

	assert(t->op == '.');
	assert(t->left != NULL && t->left->cnfa.nstates > 0);
	assert(t->right != NULL && t->right->cnfa.nstates > 0);

	d = newdfa(v, &t->left->cnfa, &v->g->cmap, &da);
	if (ISERR())
		return v->err;
	d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, &d2a);
	if (ISERR()) {
		freedfa(d);
		return v->err;
	}

	/* pick a tentative midpoint */
	mid = longest(v, d, begin, end, (int *)NULL);
	if (mid == NULL) {
		freedfa(d);
		freedfa(d2);
		return REG_ASSERT;
	}
	MDEBUG(("tentative midpoint %ld\n", LOFF(mid)));

	/* iterate until satisfaction or failure */
	while (longest(v, d2, mid, end, (int *)NULL) != end) {
		/* that midpoint didn't work, find a new one */
		if (mid == begin) {
			/* all possibilities exhausted! */
			MDEBUG(("no midpoint!\n"));
			freedfa(d);
			freedfa(d2);
			return REG_ASSERT;
		}
		mid = longest(v, d, begin, mid-1, (int *)NULL);
		if (mid == NULL) {
			/* failed to find a new one! */
			MDEBUG(("failed midpoint!\n"));
			freedfa(d);
			freedfa(d2);
			return REG_ASSERT;
		}
		MDEBUG(("new midpoint %ld\n", LOFF(mid)));
	}

	/* satisfaction */
	MDEBUG(("successful\n"));
	freedfa(d);
	freedfa(d2);
	i = dissect(v, t->left, begin, mid);
	if (i != REG_OKAY)
		return i;
	return dissect(v, t->right, mid, end);
}

/*
 - altdissect - determine alternative subexpression matches (uncomplicated)
 ^ static int altdissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
altdissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	struct smalldfa da;
	struct dfa *d;
	int i;

	assert(t != NULL);
	assert(t->op == '|');

	for (i = 0; t != NULL; t = t->right, i++) {
		MDEBUG(("trying %dth\n", i));
		assert(t->left != NULL && t->left->cnfa.nstates > 0);
		d = newdfa(v, &t->left->cnfa, &v->g->cmap, &da);
		if (ISERR())
			return v->err;
		if (longest(v, d, begin, end, (int *)NULL) == end) {
			MDEBUG(("success\n"));
			freedfa(d);
			return dissect(v, t->left, begin, end);
		}
		freedfa(d);
	}
	return REG_ASSERT;	/* none of them matched?!? */
}

/*
 - cdissect - determine subexpression matches (with complications)
 * The retry memory stores the offset of the trial midpoint from begin, 
 * plus 1 so that 0 uniquely means "clean slate".
 ^ static int cdissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
cdissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	int er;

	assert(t != NULL);
	MDEBUG(("cdissect %ld-%ld\n", LOFF(begin), LOFF(end)));

	switch (t->op) {
	case '=':		/* terminal node */
		assert(t->left == NULL && t->right == NULL);
		return REG_OKAY;	/* no action, parent did the work */
		break;
	case '|':		/* alternation */
		assert(t->left != NULL);
		return caltdissect(v, t, begin, end);
		break;
	case 'b':		/* back ref -- shouldn't be calling us! */
		assert(t->left == NULL && t->right == NULL);
		return cbrdissect(v, t, begin, end);
		break;
	case '.':		/* concatenation */
		assert(t->left != NULL && t->right != NULL);
		return ccondissect(v, t, begin, end);
		break;
	case '(':		/* capturing */
		assert(t->left != NULL && t->right == NULL);
		assert(t->subno > 0);
		er = cdissect(v, t->left, begin, end);
		if (er == REG_OKAY)
			subset(v, t, begin, end);
		return er;
		break;
	default:
		return REG_ASSERT;
		break;
	}
}

/*
 - ccondissect - concatenation subexpression matches (with complications)
 * The retry memory stores the offset of the trial midpoint from begin, 
 * plus 1 so that 0 uniquely means "clean slate".
 ^ static int ccondissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
ccondissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	struct smalldfa da;
	struct dfa *d;
	struct smalldfa d2a;
	struct dfa *d2;
	chr *mid;
	int er;

	assert(t->op == '.');
	assert(t->left != NULL && t->left->cnfa.nstates > 0);
	assert(t->right != NULL && t->right->cnfa.nstates > 0);

	if (t->left->flags&SHORTER)		/* reverse scan */
		return crevdissect(v, t, begin, end);

	d = newdfa(v, &t->left->cnfa, &v->g->cmap, &da);
	if (ISERR())
		return v->err;
	d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, &d2a);
	if (ISERR()) {
		freedfa(d);
		return v->err;
	}
	MDEBUG(("cconcat %d\n", t->retry));

	/* pick a tentative midpoint */
	if (v->mem[t->retry] == 0) {
		mid = longest(v, d, begin, end, (int *)NULL);
		if (mid == NULL) {
			freedfa(d);
			freedfa(d2);
			return REG_NOMATCH;
		}
		MDEBUG(("tentative midpoint %ld\n", LOFF(mid)));
		v->mem[t->retry] = (mid - begin) + 1;
	} else {
		mid = begin + (v->mem[t->retry] - 1);
		MDEBUG(("working midpoint %ld\n", LOFF(mid)));
	}

	/* iterate until satisfaction or failure */
	for (;;) {
		/* try this midpoint on for size */
		er = cdissect(v, t->left, begin, mid);
		if (er == REG_OKAY &&
				longest(v, d2, mid, end, (int *)NULL) == end &&
				(er = cdissect(v, t->right, mid, end)) == 
								REG_OKAY)
			break;			/* NOTE BREAK OUT */
		if (er != REG_OKAY && er != REG_NOMATCH) {
			freedfa(d);
			freedfa(d2);
			return er;
		}

		/* that midpoint didn't work, find a new one */
		if (mid == begin) {
			/* all possibilities exhausted */
			MDEBUG(("%d no midpoint\n", t->retry));
			freedfa(d);
			freedfa(d2);
			return REG_NOMATCH;
		}
		mid = longest(v, d, begin, mid-1, (int *)NULL);
		if (mid == NULL) {
			/* failed to find a new one */
			MDEBUG(("%d failed midpoint\n", t->retry));
			freedfa(d);
			freedfa(d2);
			return REG_NOMATCH;
		}
		MDEBUG(("%d: new midpoint %ld\n", t->retry, LOFF(mid)));
		v->mem[t->retry] = (mid - begin) + 1;
		zapmem(v, t->left);
		zapmem(v, t->right);
	}

	/* satisfaction */
	MDEBUG(("successful\n"));
	freedfa(d);
	freedfa(d2);
	return REG_OKAY;
}

/*
 - crevdissect - determine shortest-first subexpression matches
 * The retry memory stores the offset of the trial midpoint from begin, 
 * plus 1 so that 0 uniquely means "clean slate".
 ^ static int crevdissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
crevdissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	struct smalldfa da;
	struct dfa *d;
	struct smalldfa d2a;
	struct dfa *d2;
	chr *mid;
	int er;

	assert(t->op == '.');
	assert(t->left != NULL && t->left->cnfa.nstates > 0);
	assert(t->right != NULL && t->right->cnfa.nstates > 0);
	assert(t->left->flags&SHORTER);

	/* concatenation -- need to split the substring between parts */
	d = newdfa(v, &t->left->cnfa, &v->g->cmap, &da);
	if (ISERR())
		return v->err;
	d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, &d2a);
	if (ISERR()) {
		freedfa(d);
		return v->err;
	}
	MDEBUG(("crev %d\n", t->retry));

	/* pick a tentative midpoint */
	if (v->mem[t->retry] == 0) {
		mid = shortest(v, d, begin, begin, end, (chr **)NULL, (int *)NULL);
		if (mid == NULL) {
			freedfa(d);
			freedfa(d2);
			return REG_NOMATCH;
		}
		MDEBUG(("tentative midpoint %ld\n", LOFF(mid)));
		v->mem[t->retry] = (mid - begin) + 1;
	} else {
		mid = begin + (v->mem[t->retry] - 1);
		MDEBUG(("working midpoint %ld\n", LOFF(mid)));
	}

	/* iterate until satisfaction or failure */
	for (;;) {
		/* try this midpoint on for size */
		er = cdissect(v, t->left, begin, mid);
		if (er == REG_OKAY &&
				longest(v, d2, mid, end, (int *)NULL) == end &&
				(er = cdissect(v, t->right, mid, end)) == 
								REG_OKAY)
			break;			/* NOTE BREAK OUT */
		if (er != REG_OKAY && er != REG_NOMATCH) {
			freedfa(d);
			freedfa(d2);
			return er;
		}

		/* that midpoint didn't work, find a new one */
		if (mid == end) {
			/* all possibilities exhausted */
			MDEBUG(("%d no midpoint\n", t->retry));
			freedfa(d);
			freedfa(d2);
			return REG_NOMATCH;
		}
		mid = shortest(v, d, begin, mid+1, end, (chr **)NULL, (int *)NULL);
		if (mid == NULL) {
			/* failed to find a new one */
			MDEBUG(("%d failed midpoint\n", t->retry));
			freedfa(d);
			freedfa(d2);
			return REG_NOMATCH;
		}
		MDEBUG(("%d: new midpoint %ld\n", t->retry, LOFF(mid)));
		v->mem[t->retry] = (mid - begin) + 1;
		zapmem(v, t->left);
		zapmem(v, t->right);
	}

	/* satisfaction */
	MDEBUG(("successful\n"));
	freedfa(d);
	freedfa(d2);
	return REG_OKAY;
}

/*
 - cbrdissect - determine backref subexpression matches
 ^ static int cbrdissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
cbrdissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	int i;
	int n = t->subno;
	size_t len;
	chr *paren;
	chr *p;
	chr *stop;
	int min = t->min;
	int max = t->max;

	assert(t != NULL);
	assert(t->op == 'b');
	assert(n >= 0);
	assert((size_t)n < v->nmatch);

	MDEBUG(("cbackref n%d %d{%d-%d}\n", t->retry, n, min, max));

	if (v->pmatch[n].rm_so == -1)
		return REG_NOMATCH;
	paren = v->start + v->pmatch[n].rm_so;
	len = v->pmatch[n].rm_eo - v->pmatch[n].rm_so;

	/* no room to maneuver -- retries are pointless */
	if (v->mem[t->retry])
		return REG_NOMATCH;
	v->mem[t->retry] = 1;

	/* special-case zero-length string */
	if (len == 0) {
		if (begin == end)
			return REG_OKAY;
		return REG_NOMATCH;
	}

	/* and too-short string */
	assert(end >= begin);
	if ((size_t)(end - begin) < len)
		return REG_NOMATCH;
	stop = end - len;

	/* count occurrences */
	i = 0;
	for (p = begin; p <= stop && (i < max || max == INFINITY); p += len) {
		if ((*v->g->compare)(paren, p, len) != 0)
				break;
		i++;
	}
	MDEBUG(("cbackref found %d\n", i));

	/* and sort it out */
	if (p != end)			/* didn't consume all of it */
		return REG_NOMATCH;
	if (min <= i && (i <= max || max == INFINITY))
		return REG_OKAY;
	return REG_NOMATCH;		/* out of range */
}

/*
 - caltdissect - determine alternative subexpression matches (w. complications)
 ^ static int caltdissect(struct vars *, struct subre *, chr *, chr *);
 */
static int			/* regexec return code */
caltdissect(v, t, begin, end)
struct vars *v;
struct subre *t;
chr *begin;			/* beginning of relevant substring */
chr *end;			/* end of same */
{
	struct smalldfa da;
	struct dfa *d;
	int er;
#	define	UNTRIED	0	/* not yet tried at all */
#	define	TRYING	1	/* top matched, trying submatches */
#	define	TRIED	2	/* top didn't match or submatches exhausted */

	if (t == NULL)
		return REG_NOMATCH;
	assert(t->op == '|');
	if (v->mem[t->retry] == TRIED)
		return caltdissect(v, t->right, begin, end);

	MDEBUG(("calt n%d\n", t->retry));
	assert(t->left != NULL);

	if (v->mem[t->retry] == UNTRIED) {
		d = newdfa(v, &t->left->cnfa, &v->g->cmap, &da);
		if (ISERR())
			return v->err;
		if (longest(v, d, begin, end, (int *)NULL) != end) {
			freedfa(d);
			v->mem[t->retry] = TRIED;
			return caltdissect(v, t->right, begin, end);
		}
		freedfa(d);
		MDEBUG(("calt matched\n"));
		v->mem[t->retry] = TRYING;
	}

	er = cdissect(v, t->left, begin, end);
	if (er != REG_NOMATCH)
		return er;

	v->mem[t->retry] = TRIED;
	return caltdissect(v, t->right, begin, end);
}



#include "rege_dfa.c"