1 /* NOTE: this is derived from Henry Spencer's regexp code, and should not
2 * confused with the original package (see point 3 below). Thanks, Henry!
5 /* Additional note: this code is very heavily munged from Henry's version
6 * in places. In some spots I've traded clarity for efficiency, so don't
7 * blame Henry for some of the lack of readability.
10 /* $RCSfile: regexec.c,v $$Revision: 4.0.1.2 $$Date: 91/06/07 11:50:33 $
13 * Revision 4.0.1.2 91/06/07 11:50:33 lwall
14 * patch4: new copyright notice
15 * patch4: // wouldn't use previous pattern if it started with a null character
17 * Revision 4.0.1.1 91/04/12 09:07:39 lwall
18 * patch1: regexec only allocated space for 9 subexpresssions
20 * Revision 4.0 91/03/20 01:39:16 lwall
26 * regcomp and regexec -- regsub and regerror are not used in perl
28 * Copyright (c) 1986 by University of Toronto.
29 * Written by Henry Spencer. Not derived from licensed software.
31 * Permission is granted to anyone to use this software for any
32 * purpose on any computer system, and to redistribute it freely,
33 * subject to the following restrictions:
35 * 1. The author is not responsible for the consequences of use of
36 * this software, no matter how awful, even if they arise
39 * 2. The origin of this software must not be misrepresented, either
40 * by explicit claim or by omission.
42 * 3. Altered versions must be plainly marked as such, and must not
43 * be misrepresented as being the original software.
45 **** Alterations to Henry's code are...
47 **** Copyright (c) 1991, Larry Wall
49 **** You may distribute under the terms of either the GNU General Public
50 **** License or the Artistic License, as specified in the README file.
52 * Beware that some of this code is subtly aware of the way operator
53 * precedence is structured in regular expressions. Serious changes in
54 * regular-expression syntax might require a total rethink.
68 #define isALNUM(c) (isascii(c) && (isalpha(c) || isdigit(c) || c == '_'))
69 #define isSPACE(c) (isascii(c) && isspace(c))
70 #define isDIGIT(c) (isascii(c) && isdigit(c))
71 #define isUPPER(c) (isascii(c) && isupper(c))
78 * Global work variables for regexec().
80 static char *regprecomp;
81 static char *reginput; /* String-input pointer. */
82 static char regprev; /* char before regbol, \n if none */
83 static char *regbol; /* Beginning of input, for ^ check. */
84 static char *regeol; /* End of input, for $ check. */
85 static char **regstartp; /* Pointer to startp array. */
86 static char **regendp; /* Ditto for endp. */
87 static char *reglastparen; /* Similarly for lastparen. */
90 static int regmyp_size = 0;
91 static char **regmystartp = Null(char**);
92 static char **regmyendp = Null(char**);
98 STATIC int regmatch();
99 STATIC int regrepeat();
101 extern int multiline;
104 - regexec - match a regexp against a string
107 regexec(prog, stringarg, strend, strbeg, minend, screamer, safebase)
108 register regexp *prog;
110 register char *strend; /* pointer to null at end of string */
111 char *strbeg; /* real beginning of string */
112 int minend; /* end of match must be at least minend after stringarg */
114 int safebase; /* no need to remember string in subbase */
119 register char *string = stringarg;
121 int minlen = 0; /* must match at least this many chars */
122 int dontbother = 0; /* how many characters not to try at end */
125 if (prog == NULL || string == NULL) {
126 fatal("NULL regexp parameter");
130 if (string == strbeg) /* is ^ valid at stringarg? */
133 regprev = stringarg[-1];
134 if (!multiline && regprev == '\n')
135 regprev = '\0'; /* force ^ to NOT match */
137 regprecomp = prog->precomp;
138 /* Check validity of program. */
139 if (UCHARAT(prog->program) != MAGIC) {
140 FAIL("corrupted regexp program");
143 if (prog->do_folding) {
146 New(1101,c,i+1,char);
147 (void)bcopy(string, c, i+1);
150 for (s = string; s < strend; s++)
155 /* If there is a "must appear" string, look for it. */
157 if (prog->regmust != Nullstr &&
158 (!(prog->reganch & ROPT_ANCH)
159 || (multiline && prog->regback >= 0)) ) {
160 if (stringarg == strbeg && screamer) {
161 if (screamfirst[prog->regmust->str_rare] >= 0)
162 s = screaminstr(screamer,prog->regmust);
168 s = fbminstr((unsigned char*)s, (unsigned char*)strend,
172 ++prog->regmust->str_u.str_useful; /* hooray */
173 goto phooey; /* not present */
175 else if (prog->regback >= 0) {
179 minlen = prog->regback + prog->regmust->str_cur;
181 else if (--prog->regmust->str_u.str_useful < 0) { /* boo */
182 str_free(prog->regmust);
183 prog->regmust = Nullstr; /* disable regmust */
188 minlen = prog->regmust->str_cur;
192 /* Mark beginning of line for ^ . */
195 /* Mark end of line for $ (and such) */
198 /* see how far we have to get to not match where we matched before */
199 regtill = string+minend;
201 /* Allocate our backreference arrays */
202 if ( regmyp_size < prog->nparens + 1 ) {
203 /* Allocate or enlarge the arrays */
204 regmyp_size = prog->nparens + 1;
205 if ( regmyp_size < 10 ) regmyp_size = 10; /* minimum */
207 /* reallocate larger */
208 Renew(regmystartp,regmyp_size,char*);
209 Renew(regmyendp, regmyp_size,char*);
212 /* Initial allocation */
213 New(1102,regmystartp,regmyp_size,char*);
214 New(1102,regmyendp, regmyp_size,char*);
219 /* Simplest case: anchored match need be tried only once. */
220 /* [unless multiline is set] */
221 if (prog->reganch & ROPT_ANCH) {
222 if (regtry(prog, string))
224 else if (multiline) {
226 dontbother = minlen - 1;
227 strend -= dontbother;
228 /* for multiline we only have to try after newlines */
233 if (s < strend && regtry(prog, s))
241 /* Messy cases: unanchored match. */
242 if (prog->regstart) {
243 if (prog->reganch & ROPT_SKIP) { /* we have /x+whatever/ */
244 /* it must be a one character string */
245 i = prog->regstart->str_ptr[0];
251 while (s < strend && *s == i)
257 else if (prog->regstart->str_pok == 3) {
258 /* We know what string it must start with. */
260 while ((s = fbminstr((unsigned char*)s,
261 (unsigned char*)strend, prog->regstart)) != NULL)
272 c = prog->regstart->str_ptr;
273 while ((s = ninstr(s, strend,
274 c, c + prog->regstart->str_cur )) != NULL) {
282 if (c = prog->regstclass) {
283 int doevery = (prog->reganch & ROPT_SKIP) == 0;
286 dontbother = minlen - 1;
287 strend -= dontbother; /* don't bother with what can't match */
289 /* We know what class it must start with. */
295 if (!(c[i >> 3] & (1 << (i&7)))) {
296 if (tmp && regtry(prog, s))
308 dontbother++,strend--;
314 tmp = isALNUM(regprev); /* assume not alphanumeric */
317 if (tmp != isALNUM(i)) {
324 if ((minlen || tmp) && regtry(prog,s))
329 dontbother++,strend--;
335 tmp = isALNUM(regprev); /* assume not alphanumeric */
338 if (tmp != isALNUM(i))
340 else if (regtry(prog, s))
344 if ((minlen || !tmp) && regtry(prog,s))
351 if (tmp && regtry(prog, s))
365 if (tmp && regtry(prog, s))
378 if (tmp && regtry(prog, s))
391 if (tmp && regtry(prog, s))
404 if (tmp && regtry(prog, s))
417 if (tmp && regtry(prog, s))
431 dontbother = minlen - 1;
432 strend -= dontbother;
433 /* We don't know much -- general case. */
437 } while (s++ < strend);
444 if ((!safebase && (prog->nparens || sawampersand)) || prog->do_folding){
445 strend += dontbother; /* uncheat */
446 if (safebase) /* no need for $digit later */
448 else if (strbeg != prog->subbase) {
449 i = strend - string + (stringarg - strbeg);
450 s = nsavestr(strbeg,i); /* so $digit will work later */
452 Safefree(prog->subbase);
453 prog->subbeg = prog->subbase = s;
458 s += (stringarg - strbeg);
459 for (i = 0; i <= prog->nparens; i++) {
461 prog->startp[i] = s + (prog->startp[i] - string);
462 prog->endp[i] = s + (prog->endp[i] - string);
465 if (prog->do_folding)
471 if (prog->do_folding)
477 - regtry - try match at specific point
479 static int /* 0 failure, 1 success */
489 regstartp = prog->startp;
490 regendp = prog->endp;
491 reglastparen = &prog->lastparen;
497 for (i = prog->nparens; i >= 0; i--) {
502 if (regmatch(prog->program + 1) && reginput >= regtill) {
503 prog->startp[0] = string;
504 prog->endp[0] = reginput;
511 - regmatch - main matching routine
513 * Conceptually the strategy is simple: check to see whether the current
514 * node matches, call self recursively to see whether the rest matches,
515 * and then act accordingly. In practice we make some effort to avoid
516 * recursion, in particular by going through "ordinary" nodes (that don't
517 * need to know whether the rest of the match failed) by a loop instead of
520 /* [lwall] I've hoisted the register declarations to the outer block in order to
521 * maybe save a little bit of pushing and popping on the stack. It also takes
522 * advantage of machines that use a register save mask on subroutine entry.
524 static int /* 0 failure, 1 success */
528 register char *scan; /* Current node. */
529 char *next; /* Next node. */
530 register int nextchar;
531 register int n; /* no or next */
532 register int ln; /* len or last */
533 register char *s; /* operand or save */
534 register char *locinput = reginput;
536 nextchar = *locinput;
539 if (scan != NULL && regnarrate)
540 fprintf(stderr, "%s(\n", regprop(scan));
542 while (scan != NULL) {
545 fprintf(stderr, "%s...\n", regprop(scan));
549 next = scan + NEXT(scan);
553 next = regnext(scan);
558 if (locinput == regbol ? regprev == '\n' :
559 ((nextchar || locinput < regeol) &&
560 locinput[-1] == '\n') )
562 /* regtill = regbol; */
567 if ((nextchar || locinput < regeol) && nextchar != '\n')
569 if (!multiline && regeol - locinput > 1)
571 /* regtill = regbol; */
574 if ((nextchar == '\0' && locinput >= regeol) ||
577 nextchar = *++locinput;
582 /* Inline the first character, for speed. */
585 if (regeol - locinput < ln)
587 if (ln > 1 && bcmp(s, locinput, ln) != 0)
590 nextchar = *locinput;
595 nextchar = UCHARAT(locinput);
596 if (s[nextchar >> 3] & (1 << (nextchar&7)))
598 if (!nextchar && locinput >= regeol)
600 nextchar = *++locinput;
605 if (!isALNUM(nextchar))
607 nextchar = *++locinput;
610 if (!nextchar && locinput >= regeol)
612 if (isALNUM(nextchar))
614 nextchar = *++locinput;
618 if (locinput == regbol) /* was last char in word? */
619 ln = isALNUM(regprev);
621 ln = isALNUM(locinput[-1]);
622 n = isALNUM(nextchar); /* is next char in word? */
623 if ((ln == n) == (OP(scan) == BOUND))
627 if (!nextchar && locinput >= regeol)
629 if (!isSPACE(nextchar))
631 nextchar = *++locinput;
636 if (isSPACE(nextchar))
638 nextchar = *++locinput;
641 if (!isDIGIT(nextchar))
643 nextchar = *++locinput;
646 if (!nextchar && locinput >= regeol)
648 if (isDIGIT(nextchar))
650 nextchar = *++locinput;
653 n = ARG1(scan); /* which paren pair */
659 if (s == regmyendp[n])
661 /* Inline the first character, for speed. */
664 ln = regmyendp[n] - s;
665 if (locinput + ln > regeol)
667 if (ln > 1 && bcmp(s, locinput, ln) != 0)
670 nextchar = *locinput;
678 n = ARG1(scan); /* which paren pair */
681 regmystartp[n] = locinput; /* for REF */
682 if (regmatch(next)) {
684 * Don't set startp if some later
685 * invocation of the same parentheses
688 if (regstartp[n] == NULL)
689 regstartp[n] = locinput;
695 n = ARG1(scan); /* which paren pair */
698 regmyendp[n] = locinput; /* for REF */
699 if (regmatch(next)) {
701 * Don't set endp if some later
702 * invocation of the same parentheses
705 if (regendp[n] == NULL) {
706 regendp[n] = locinput;
707 if (n > *reglastparen)
716 if (OP(next) != BRANCH) /* No choice. */
717 next = NEXTOPER(scan); /* Avoid recursion. */
721 if (regmatch(NEXTOPER(scan)))
729 scan = regnext(scan);
731 } while (scan != NULL && OP(scan) == BRANCH);
738 ln = ARG1(scan); /* min to match */
739 n = ARG2(scan); /* max to match */
740 scan = NEXTOPER(scan) + 4;
745 scan = NEXTOPER(scan);
749 * Lookahead to avoid useless match attempts
750 * when we know what character comes next.
754 scan = NEXTOPER(scan);
756 if (OP(next) == EXACTLY)
757 nextchar = *(OPERAND(next)+1);
761 n = regrepeat(scan, n);
762 if (!multiline && OP(next) == EOL && ln < n)
763 ln = n; /* why back off? */
765 /* If it could work, try it. */
766 if (nextchar == -1000 || *reginput == nextchar)
769 /* Couldn't or didn't -- back up. */
771 reginput = locinput + n;
775 reginput = locinput; /* put where regtry can find it */
776 return(1); /* Success! */
778 printf("%x %d\n",scan,scan[1]);
779 FAIL("regexp memory corruption");
786 * We get here only if there's trouble -- normally "case END" is
787 * the terminating point.
789 FAIL("corrupted regexp pointers");
797 - regrepeat - repeatedly match something simple, report how many
800 * [This routine now assumes that it will only match on things of length 1.
801 * That was true before, but now we assume scan - reginput is the count,
802 * rather than incrementing count on every character.]
812 register char *loceol = regeol;
815 if (max && max < loceol - scan)
820 while (scan < loceol && *scan != '\n')
823 case EXACTLY: /* length of string is 1 */
825 while (scan < loceol && *opnd == *scan)
830 while (scan < loceol && !(opnd[c >> 3] & (1 << (c & 7)))) {
836 while (scan < loceol && isALNUM(*scan))
840 while (scan < loceol && !isALNUM(*scan))
844 while (scan < loceol && isSPACE(*scan))
848 while (scan < loceol && !isSPACE(*scan))
852 while (scan < loceol && isDIGIT(*scan))
856 while (scan < loceol && !isDIGIT(*scan))
859 default: /* Oh dear. Called inappropriately. */
860 FAIL("internal regexp foulup");
871 - regnext - dig the "next" pointer out of a node
873 * [Note, when REGALIGN is defined there are two places in regmatch()
874 * that bypass this code for speed.]