2
* The matching engine and friends. This file is #included by regexec.c
3
* after suitable #defines of a variety of macros used herein, so that
4
* different state representations can be used without duplicating masses
9
#define matcher smatcher
12
#define dissect sdissect
13
#define backref sbackref
20
#define matcher lmatcher
23
#define dissect ldissect
24
#define backref lbackref
31
/* another structure passed up and down to avoid zillions of parameters */
35
regmatch_t *pmatch; /* [nsub+1] (0 element unused) */
36
char *offp; /* offsets work from here */
37
char *beginp; /* start of string -- virtual NUL precedes */
38
char *endp; /* end of string -- virtual NUL here */
39
char *coldp; /* can be no match starting before here */
40
char **lastpos; /* [nplus+1] */
42
states st; /* current states */
43
states fresh; /* states for a fresh start */
44
states tmp; /* temporary */
45
states empty; /* empty set of states */
51
#define SP(t, s, c) print(m, t, s, c, stdout)
52
#define AT(t, p1, p2, s1, s2) at(m, t, p1, p2, s1, s2)
53
#define NOTE(str) { if (m->eflags®_TRACE) printf("=%s\n", (str)); }
55
#define SP(t, s, c) /* nothing */
56
#define AT(t, p1, p2, s1, s2) /* nothing */
57
#define NOTE(s) /* nothing */
61
- matcher - the actual matching engine
62
== static int matcher(register struct re_guts *g, char *string, \
63
== size_t nmatch, regmatch_t pmatch[], int eflags);
65
static int /* 0 success, REG_NOMATCH failure */
66
matcher(g, string, nmatch, pmatch, eflags)
67
register struct re_guts *g;
74
register unsigned int i;
76
register struct match *m = &mv;
78
register const sopno gf = g->firststate+1; /* +1 for OEND */
79
register const sopno gl = g->laststate;
83
/* simplify the situation where possible */
84
if (g->cflags®_NOSUB)
86
if (eflags®_STARTEND) {
87
start = string + pmatch[0].rm_so;
88
stop = string + pmatch[0].rm_eo;
91
stop = start + strlen(start);
96
/* prescreening; this does wonders for this rather slow code */
97
if (g->must != NULL) {
98
for (dp = start; dp < stop; dp++)
99
if (*dp == g->must[0] && stop - dp >= g->mlen &&
100
memcmp(dp, g->must, (size_t)g->mlen) == 0)
102
if (dp == stop) /* we didn't find g->must */
106
/* match struct setup */
121
/* this loop does only one repetition except for backrefs */
123
endp = fast(m, start, stop, gf, gl);
124
if (endp == NULL) { /* a miss */
128
if (nmatch == 0 && !g->backrefs)
129
break; /* no further info needed */
132
assert(m->coldp != NULL);
134
NOTE("finding start");
135
endp = slow(m, m->coldp, stop, gf, gl);
138
assert(m->coldp < m->endp);
141
if (nmatch == 1 && !g->backrefs)
142
break; /* no further info needed */
144
/* oh my, he wants the subexpressions... */
145
if (m->pmatch == NULL)
146
m->pmatch = (regmatch_t *)malloc((m->g->nsub + 1) *
148
if (m->pmatch == NULL) {
152
for (i = 1; i <= m->g->nsub; i++)
153
m->pmatch[i].rm_so = m->pmatch[i].rm_eo = -1;
154
if (!g->backrefs && !(m->eflags®_BACKR)) {
156
dp = dissect(m, m->coldp, endp, gf, gl);
158
if (g->nplus > 0 && m->lastpos == NULL)
159
m->lastpos = (char **)malloc((g->nplus+1) *
161
if (g->nplus > 0 && m->lastpos == NULL) {
166
NOTE("backref dissect");
167
dp = backref(m, m->coldp, endp, gf, gl, (sopno)0);
172
/* uh-oh... we couldn't find a subexpression-level match */
173
assert(g->backrefs); /* must be back references doing it */
174
assert(g->nplus == 0 || m->lastpos != NULL);
176
if (dp != NULL || endp <= m->coldp)
179
endp = slow(m, m->coldp, endp-1, gf, gl);
182
/* try it on a shorter possibility */
184
for (i = 1; i <= m->g->nsub; i++) {
185
assert(m->pmatch[i].rm_so == -1);
186
assert(m->pmatch[i].rm_eo == -1);
189
NOTE("backoff dissect");
190
dp = backref(m, m->coldp, endp, gf, gl, (sopno)0);
192
assert(dp == NULL || dp == endp);
193
if (dp != NULL) /* found a shorter one */
196
/* despite initial appearances, there is no match here */
198
start = m->coldp + 1; /* recycle starting later */
199
assert(start <= stop);
202
/* fill in the details if requested */
204
pmatch[0].rm_so = m->coldp - m->offp;
205
pmatch[0].rm_eo = endp - m->offp;
208
assert(m->pmatch != NULL);
209
for (i = 1; i < nmatch; i++)
211
pmatch[i] = m->pmatch[i];
213
pmatch[i].rm_so = -1;
214
pmatch[i].rm_eo = -1;
218
if (m->pmatch != NULL)
219
free((char *)m->pmatch);
220
if (m->lastpos != NULL)
221
free((char *)m->lastpos);
227
- dissect - figure out what matched what, no back references
228
== static char *dissect(register struct match *m, char *start, \
229
== char *stop, sopno startst, sopno stopst);
231
static char * /* == stop (success) always */
232
dissect(m, start, stop, startst, stopst)
233
register struct match *m;
240
register sopno ss; /* start sop of current subRE */
241
register sopno es; /* end sop of current subRE */
242
register char *sp; /* start of string matched by it */
243
register char *stp; /* string matched by it cannot pass here */
244
register char *rest; /* start of rest of string */
245
register char *tail; /* string unmatched by rest of RE */
246
register sopno ssub; /* start sop of subsubRE */
247
register sopno esub; /* end sop of subsubRE */
248
register char *ssp; /* start of string matched by subsubRE */
249
register char *sep; /* end of string matched by subsubRE */
250
register char *oldssp; /* previous ssp */
253
AT("diss", start, stop, startst, stopst);
255
for (ss = startst; ss < stopst; ss = es) {
256
/* identify end of subRE */
258
switch (OP(m->g->strip[es])) {
261
es += OPND(m->g->strip[es]);
264
while (OP(m->g->strip[es]) != O_CH)
265
es += OPND(m->g->strip[es]);
270
/* figure out what it matched */
271
switch (OP(m->g->strip[ss])) {
291
/* cases where length of match is hard to find */
295
/* how long could this one be? */
296
rest = slow(m, sp, stp, ss, es);
297
assert(rest != NULL); /* it did match */
298
/* could the rest match the rest? */
299
tail = slow(m, rest, stop, es, stopst);
302
/* no -- try a shorter match for this one */
304
assert(stp >= sp); /* it did work */
308
/* did innards match? */
309
if (slow(m, sp, rest, ssub, esub) != NULL) {
310
dp = dissect(m, sp, rest, ssub, esub);
319
/* how long could this one be? */
320
rest = slow(m, sp, stp, ss, es);
321
assert(rest != NULL); /* it did match */
322
/* could the rest match the rest? */
323
tail = slow(m, rest, stop, es, stopst);
326
/* no -- try a shorter match for this one */
328
assert(stp >= sp); /* it did work */
334
for (;;) { /* find last match of innards */
335
sep = slow(m, ssp, rest, ssub, esub);
336
if (sep == NULL || sep == ssp)
337
break; /* failed or matched null */
338
oldssp = ssp; /* on to next try */
342
/* last successful match */
346
assert(sep == rest); /* must exhaust substring */
347
assert(slow(m, ssp, sep, ssub, esub) == rest);
348
dp = dissect(m, ssp, sep, ssub, esub);
355
/* how long could this one be? */
356
rest = slow(m, sp, stp, ss, es);
357
assert(rest != NULL); /* it did match */
358
/* could the rest match the rest? */
359
tail = slow(m, rest, stop, es, stopst);
362
/* no -- try a shorter match for this one */
364
assert(stp >= sp); /* it did work */
367
esub = ss + OPND(m->g->strip[ss]) - 1;
368
assert(OP(m->g->strip[esub]) == OOR1);
369
for (;;) { /* find first matching branch */
370
if (slow(m, sp, rest, ssub, esub) == rest)
371
break; /* it matched all of it */
372
/* that one missed, try next one */
373
assert(OP(m->g->strip[esub]) == OOR1);
375
assert(OP(m->g->strip[esub]) == OOR2);
377
esub += OPND(m->g->strip[esub]);
378
if (OP(m->g->strip[esub]) == OOR2)
381
assert(OP(m->g->strip[esub]) == O_CH);
383
dp = dissect(m, sp, rest, ssub, esub);
395
i = OPND(m->g->strip[ss]);
396
assert(0 < i && i <= m->g->nsub);
397
m->pmatch[i].rm_so = sp - m->offp;
400
i = OPND(m->g->strip[ss]);
401
assert(0 < i && i <= m->g->nsub);
402
m->pmatch[i].rm_eo = sp - m->offp;
415
- backref - figure out what matched what, figuring in back references
416
== static char *backref(register struct match *m, char *start, \
417
== char *stop, sopno startst, sopno stopst, sopno lev);
419
static char * /* == stop (success) or NULL (failure) */
420
backref(m, start, stop, startst, stopst, lev)
421
register struct match *m;
426
sopno lev; /* PLUS nesting level */
429
register sopno ss; /* start sop of current subRE */
430
register char *sp; /* start of string matched by it */
431
register sopno ssub; /* start sop of subsubRE */
432
register sopno esub; /* end sop of subsubRE */
433
register char *ssp; /* start of string matched by subsubRE */
438
register regoff_t offsave;
441
AT("back", start, stop, startst, stopst);
444
/* get as far as we can with easy stuff */
446
for (ss = startst; !hard && ss < stopst; ss++)
447
switch (OP(s = m->g->strip[ss])) {
449
if (sp == stop || *sp++ != (char)OPND(s))
458
cs = &m->g->sets[OPND(s)];
459
if (sp == stop || !CHIN(cs, *sp++))
463
if ( (sp == m->beginp && !(m->eflags®_NOTBOL)) ||
464
(sp < m->endp && *(sp-1) == '\n' &&
465
(m->g->cflags®_NEWLINE)) )
471
if ( (sp == m->endp && !(m->eflags®_NOTEOL)) ||
472
(sp < m->endp && *sp == '\n' &&
473
(m->g->cflags®_NEWLINE)) )
479
if (( (sp == m->beginp && !(m->eflags®_NOTBOL)) ||
480
(sp < m->endp && *(sp-1) == '\n' &&
481
(m->g->cflags®_NEWLINE)) ||
483
!ISWORD(*(sp-1))) ) &&
484
(sp < m->endp && ISWORD(*sp)) )
490
if (( (sp == m->endp && !(m->eflags®_NOTEOL)) ||
491
(sp < m->endp && *sp == '\n' &&
492
(m->g->cflags®_NEWLINE)) ||
493
(sp < m->endp && !ISWORD(*sp)) ) &&
494
(sp > m->beginp && ISWORD(*(sp-1))) )
501
case OOR1: /* matches null but needs to skip */
505
assert(OP(s) == OOR2);
507
} while (OP(s = m->g->strip[ss]) != O_CH);
508
/* note that the ss++ gets us past the O_CH */
510
default: /* have to make a choice */
514
if (!hard) { /* that was it! */
519
ss--; /* adjust for the for's final increment */
522
AT("hard", sp, stop, ss, stopst);
525
case OBACK_: /* the vilest depths */
527
assert(0 < i && i <= m->g->nsub);
528
if (m->pmatch[i].rm_eo == -1)
530
assert(m->pmatch[i].rm_so != -1);
531
len = m->pmatch[i].rm_eo - m->pmatch[i].rm_so;
532
assert(stop - m->beginp >= len);
534
return(NULL); /* not enough left to match */
535
ssp = m->offp + m->pmatch[i].rm_so;
536
if (memcmp(sp, ssp, len) != 0)
538
while (m->g->strip[ss] != SOP(O_BACK, i))
540
return(backref(m, sp+len, stop, ss+1, stopst, lev));
542
case OQUEST_: /* to null or not */
543
dp = backref(m, sp, stop, ss+1, stopst, lev);
545
return(dp); /* not */
546
return(backref(m, sp, stop, ss+OPND(s)+1, stopst, lev));
549
assert(m->lastpos != NULL);
550
assert(lev+1 <= m->g->nplus);
551
m->lastpos[lev+1] = sp;
552
return(backref(m, sp, stop, ss+1, stopst, lev+1));
555
if (sp == m->lastpos[lev]) /* last pass matched null */
556
return(backref(m, sp, stop, ss+1, stopst, lev-1));
557
/* try another pass */
558
m->lastpos[lev] = sp;
559
dp = backref(m, sp, stop, ss-OPND(s)+1, stopst, lev);
561
return(backref(m, sp, stop, ss+1, stopst, lev-1));
565
case OCH_: /* find the right one, if any */
567
esub = ss + OPND(s) - 1;
568
assert(OP(m->g->strip[esub]) == OOR1);
569
for (;;) { /* find first matching branch */
570
dp = backref(m, sp, stop, ssub, esub, lev);
573
/* that one missed, try next one */
574
if (OP(m->g->strip[esub]) == O_CH)
575
return(NULL); /* there is none */
577
assert(OP(m->g->strip[esub]) == OOR2);
579
esub += OPND(m->g->strip[esub]);
580
if (OP(m->g->strip[esub]) == OOR2)
583
assert(OP(m->g->strip[esub]) == O_CH);
586
case OLPAREN: /* must undo assignment if rest fails */
588
assert(0 < i && i <= m->g->nsub);
589
offsave = m->pmatch[i].rm_so;
590
m->pmatch[i].rm_so = sp - m->offp;
591
dp = backref(m, sp, stop, ss+1, stopst, lev);
594
m->pmatch[i].rm_so = offsave;
597
case ORPAREN: /* must undo assignment if rest fails */
599
assert(0 < i && i <= m->g->nsub);
600
offsave = m->pmatch[i].rm_eo;
601
m->pmatch[i].rm_eo = sp - m->offp;
602
dp = backref(m, sp, stop, ss+1, stopst, lev);
605
m->pmatch[i].rm_eo = offsave;
620
- fast - step through the string at top speed
621
== static char *fast(register struct match *m, char *start, \
622
== char *stop, sopno startst, sopno stopst);
624
static char * /* where tentative match ended, or NULL */
625
fast(m, start, stop, startst, stopst)
626
register struct match *m;
632
register states st = m->st;
633
register states fresh = m->fresh;
634
register states tmp = m->tmp;
635
register char *p = start;
636
register int c = (start == m->beginp) ? OUT : *(start-1);
637
register int lastc; /* previous c */
640
register char *coldp; /* last p after which no match was underway */
644
st = step(m->g, startst, stopst, st, NOTHING, st);
651
c = (p == m->endp) ? OUT : *p;
655
/* is there an EOL and/or BOL between lastc and c? */
658
if ( (lastc == '\n' && m->g->cflags®_NEWLINE) ||
659
(lastc == OUT && !(m->eflags®_NOTBOL)) ) {
663
if ( (c == '\n' && m->g->cflags®_NEWLINE) ||
664
(c == OUT && !(m->eflags®_NOTEOL)) ) {
665
flagch = (flagch == BOL) ? BOLEOL : EOL;
670
st = step(m->g, startst, stopst, st, flagch, st);
674
/* how about a word boundary? */
675
if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
676
(c != OUT && ISWORD(c)) ) {
679
if ( (lastc != OUT && ISWORD(lastc)) &&
680
(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
683
if (flagch == BOW || flagch == EOW) {
684
st = step(m->g, startst, stopst, st, flagch, st);
689
if (ISSET(st, stopst) || p == stop)
690
break; /* NOTE BREAK OUT */
692
/* no, we must deal with this character */
696
st = step(m->g, startst, stopst, tmp, c, st);
698
assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
702
assert(coldp != NULL);
704
if (ISSET(st, stopst))
711
- slow - step through the string more deliberately
712
== static char *slow(register struct match *m, char *start, \
713
== char *stop, sopno startst, sopno stopst);
715
static char * /* where it ended */
716
slow(m, start, stop, startst, stopst)
717
register struct match *m;
723
register states st = m->st;
724
register states empty = m->empty;
725
register states tmp = m->tmp;
726
register char *p = start;
727
register int c = (start == m->beginp) ? OUT : *(start-1);
728
register int lastc; /* previous c */
731
register char *matchp; /* last p at which a match ended */
733
AT("slow", start, stop, startst, stopst);
736
SP("sstart", st, *p);
737
st = step(m->g, startst, stopst, st, NOTHING, st);
742
c = (p == m->endp) ? OUT : *p;
744
/* is there an EOL and/or BOL between lastc and c? */
747
if ( (lastc == '\n' && m->g->cflags®_NEWLINE) ||
748
(lastc == OUT && !(m->eflags®_NOTBOL)) ) {
752
if ( (c == '\n' && m->g->cflags®_NEWLINE) ||
753
(c == OUT && !(m->eflags®_NOTEOL)) ) {
754
flagch = (flagch == BOL) ? BOLEOL : EOL;
759
st = step(m->g, startst, stopst, st, flagch, st);
760
SP("sboleol", st, c);
763
/* how about a word boundary? */
764
if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
765
(c != OUT && ISWORD(c)) ) {
768
if ( (lastc != OUT && ISWORD(lastc)) &&
769
(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
772
if (flagch == BOW || flagch == EOW) {
773
st = step(m->g, startst, stopst, st, flagch, st);
774
SP("sboweow", st, c);
778
if (ISSET(st, stopst))
780
if (EQ(st, empty) || p == stop)
781
break; /* NOTE BREAK OUT */
783
/* no, we must deal with this character */
787
st = step(m->g, startst, stopst, tmp, c, st);
789
assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
798
- step - map set of states reachable before char to set reachable after
799
== static states step(register struct re_guts *g, sopno start, sopno stop, \
800
== register states bef, int ch, register states aft);
801
== #define BOL (OUT+1)
802
== #define EOL (BOL+1)
803
== #define BOLEOL (BOL+2)
804
== #define NOTHING (BOL+3)
805
== #define BOW (BOL+4)
806
== #define EOW (BOL+5)
807
== #define CODEMAX (BOL+5) // highest code used
808
== #define NONCHAR(c) ((c) > CHAR_MAX)
809
== #define NNONCHAR (CODEMAX-CHAR_MAX)
812
step(g, start, stop, bef, ch, aft)
813
register struct re_guts *g;
814
sopno start; /* start state within strip */
815
sopno stop; /* state after stop state within strip */
816
register states bef; /* states reachable before */
817
int ch; /* character or NONCHAR code */
818
register states aft; /* states already known reachable after */
823
register onestate here; /* note, macros know this name */
827
for (pc = start, INIT(here, pc); pc != stop; pc++, INC(here)) {
831
assert(pc == stop-1);
834
/* only characters can match */
835
assert(!NONCHAR(ch) || ch != (char)OPND(s));
836
if (ch == (char)OPND(s))
840
if (ch == BOL || ch == BOLEOL)
844
if (ch == EOL || ch == BOLEOL)
860
cs = &g->sets[OPND(s)];
861
if (!NONCHAR(ch) && CHIN(cs, ch))
864
case OBACK_: /* ignored here */
868
case OPLUS_: /* forward, this is just an empty */
871
case O_PLUS: /* both forward and back */
873
i = ISSETBACK(aft, OPND(s));
874
BACK(aft, aft, OPND(s));
875
if (!i && ISSETBACK(aft, OPND(s))) {
876
/* oho, must reconsider loop body */
881
case OQUEST_: /* two branches, both forward */
883
FWD(aft, aft, OPND(s));
885
case O_QUEST: /* just an empty */
888
case OLPAREN: /* not significant here */
892
case OCH_: /* mark the first two branches */
894
assert(OP(g->strip[pc+OPND(s)]) == OOR2);
895
FWD(aft, aft, OPND(s));
897
case OOR1: /* done a branch, find the O_CH */
898
if (ISSTATEIN(aft, here)) {
900
OP(s = g->strip[pc+look]) != O_CH;
902
assert(OP(s) == OOR2);
906
case OOR2: /* propagate OCH_'s marking */
908
if (OP(g->strip[pc+OPND(s)]) != O_CH) {
909
assert(OP(g->strip[pc+OPND(s)]) == OOR2);
910
FWD(aft, aft, OPND(s));
913
case O_CH: /* just empty */
916
default: /* ooooops... */
927
- print - print a set of states
929
== static void print(struct match *m, char *caption, states st, \
934
print(m, caption, st, ch, d)
941
register struct re_guts *g = m->g;
943
register int first = 1;
945
if (!(m->eflags®_TRACE))
948
fprintf(d, "%s", caption);
950
fprintf(d, " %s", pchar(ch));
951
for (i = 0; i < g->nstates; i++)
953
fprintf(d, "%s%d", (first) ? "\t" : ", ", i);
960
- at - print current situation
962
== static void at(struct match *m, char *title, char *start, char *stop, \
963
== sopno startst, sopno stopst);
967
at(m, title, start, stop, startst, stopst)
975
if (!(m->eflags®_TRACE))
978
printf("%s %s-", title, pchar(*start));
979
printf("%s ", pchar(*stop));
980
printf("%ld-%ld\n", (long)startst, (long)stopst);
984
#define PCHARDONE /* never again */
986
- pchar - make a character printable
988
== static char *pchar(int ch);
991
* Is this identical to regchar() over in debug.c? Well, yes. But a
992
* duplicate here avoids having a debugging-capable regexec.o tied to
993
* a matching debug.o, and this is convenient. It all disappears in
994
* the non-debug compilation anyway, so it doesn't matter much.
996
static char * /* -> representation */
1000
static char pbuf[10];
1002
if (isprint(ch) || ch == ' ')
1003
sprintf(pbuf, "%c", ch);
1005
sprintf(pbuf, "\\%o", ch);
added
removed
plug-ins/script-fu/re/engine.c
