5 * "One Ring to rule them all, One Ring to find them..."
8 /* NOTE: this is derived from Henry Spencer's regexp code, and should not
9 * confused with the original package (see point 3 below). Thanks, Henry!
12 /* Additional note: this code is very heavily munged from Henry's version
13 * in places. In some spots I've traded clarity for efficiency, so don't
14 * blame Henry for some of the lack of readability.
17 /* The names of the functions have been changed from regcomp and
18 * regexec to pregcomp and pregexec in order to avoid conflicts
19 * with the POSIX routines of the same names.
24 * pregcomp and pregexec -- regsub and regerror are not used in perl
26 * Copyright (c) 1986 by University of Toronto.
27 * Written by Henry Spencer. Not derived from licensed software.
29 * Permission is granted to anyone to use this software for any
30 * purpose on any computer system, and to redistribute it freely,
31 * subject to the following restrictions:
33 * 1. The author is not responsible for the consequences of use of
34 * this software, no matter how awful, even if they arise
37 * 2. The origin of this software must not be misrepresented, either
38 * by explicit claim or by omission.
40 * 3. Altered versions must be plainly marked as such, and must not
41 * be misrepresented as being the original software.
43 **** Alterations to Henry's code are...
45 **** Copyright (c) 1991-1994, Larry Wall
47 **** You may distribute under the terms of either the GNU General Public
48 **** License or the Artistic License, as specified in the README file.
50 * Beware that some of this code is subtly aware of the way operator
51 * precedence is structured in regular expressions. Serious changes in
52 * regular-expression syntax might require a total rethink.
63 static I32 regnarrate = 0;
64 static char* regprogram = 0;
67 /* Current curly descriptor */
68 typedef struct curcur CURCUR;
70 int parenfloor; /* how far back to strip paren data */
71 int cur; /* how many instances of scan we've matched */
72 int min; /* the minimal number of scans to match */
73 int max; /* the maximal number of scans to match */
74 int minmod; /* whether to work our way up or down */
75 char * scan; /* the thing to match */
76 char * next; /* what has to match after it */
77 char * lastloc; /* where we started matching this scan */
78 CURCUR * oldcc; /* current curly before we started this one */
83 typedef I32 CHECKPOINT;
85 CHECKPOINT regcppush _((I32 parenfloor));
86 char * regcppop _((void));
92 int retval = savestack_ix;
93 int i = (regsize - parenfloor) * 3;
97 for (p = regsize; p > parenfloor; p--) {
98 SSPUSHPTR(regendp[p]);
99 SSPUSHPTR(regstartp[p]);
103 SSPUSHINT(*reglastparen);
106 SSPUSHINT(SAVEt_REGCONTEXT);
117 assert(i == SAVEt_REGCONTEXT);
119 input = (char *) SSPOPPTR;
120 *reglastparen = SSPOPINT;
122 for (i -= 3; i > 0; i -= 3) {
123 paren = (U32)SSPOPINT;
124 regstartp[paren] = (char *) SSPOPPTR;
125 tmps = (char*)SSPOPPTR;
126 if (paren <= *reglastparen)
127 regendp[paren] = tmps;
129 for (paren = *reglastparen + 1; paren <= regnpar; paren++) {
131 regstartp[paren] = Nullch;
132 regendp[paren] = Nullch;
137 #define regcpblow(cp) leave_scope(cp)
140 * pregexec and friends
147 static I32 regmatch _((char *prog));
148 static I32 regrepeat _((char *p, I32 max));
149 static I32 regtry _((regexp *prog, char *startpos));
152 - pregexec - match a regexp against a string
155 pregexec(prog, stringarg, strend, strbeg, minend, screamer, safebase)
156 register regexp *prog;
158 register char *strend; /* pointer to null at end of string */
159 char *strbeg; /* real beginning of string */
160 I32 minend; /* end of match must be at least minend after stringarg */
162 I32 safebase; /* no need to remember string in subbase */
167 register char *startpos = stringarg;
169 I32 minlen = 0; /* must match at least this many chars */
170 I32 dontbother = 0; /* how many characters not to try at end */
177 regnarrate = debug & 512;
178 regprogram = prog->program;
182 if (prog == NULL || startpos == NULL) {
183 croak("NULL regexp parameter");
187 if (startpos == strbeg) /* is ^ valid at stringarg? */
190 regprev = stringarg[-1];
191 if (!multiline && regprev == '\n')
192 regprev = '\0'; /* force ^ to NOT match */
194 regprecomp = prog->precomp;
195 regnpar = prog->nparens;
196 /* Check validity of program. */
197 if (UCHARAT(prog->program) != MAGIC) {
198 FAIL("corrupted regexp program");
201 if (prog->do_folding) {
202 i = strend - startpos;
203 New(1101,c,i+1,char);
204 Copy(startpos, c, i+1, char);
206 strend = startpos + i;
207 for (s = startpos; s < strend; s++)
212 /* If there is a "must appear" string, look for it. */
214 if (prog->regmust != Nullsv &&
215 (!(prog->reganch & ROPT_ANCH)
216 || (multiline && prog->regback >= 0)) )
218 if (stringarg == strbeg && screamer) {
219 if (screamfirst[BmRARE(prog->regmust)] >= 0)
220 s = screaminstr(screamer,prog->regmust);
225 s = fbm_instr((unsigned char*)s, (unsigned char*)strend,
228 ++BmUSEFUL(prog->regmust); /* hooray */
229 goto phooey; /* not present */
231 else if (prog->regback >= 0) {
235 minlen = prog->regback + SvCUR(prog->regmust);
237 else if (!prog->naughty && --BmUSEFUL(prog->regmust) < 0) { /* boo */
238 SvREFCNT_dec(prog->regmust);
239 prog->regmust = Nullsv; /* disable regmust */
244 minlen = SvCUR(prog->regmust);
248 /* Mark beginning of line for ^ . */
251 /* Mark end of line for $ (and such) */
254 /* see how far we have to get to not match where we matched before */
255 regtill = startpos+minend;
257 /* Simplest case: anchored match need be tried only once. */
258 /* [unless multiline is set] */
259 if (prog->reganch & ROPT_ANCH) {
260 if (regtry(prog, startpos))
262 else if (multiline || (prog->reganch & ROPT_IMPLICIT)) {
264 dontbother = minlen - 1;
265 strend -= dontbother;
266 /* for multiline we only have to try after newlines */
271 if (s < strend && regtry(prog, s))
279 /* Messy cases: unanchored match. */
280 if (prog->regstart) {
281 if (prog->reganch & ROPT_SKIP) { /* we have /x+whatever/ */
282 /* it must be a one character string */
283 i = SvPVX(prog->regstart)[0];
289 while (s < strend && *s == i)
295 else if (SvPOK(prog->regstart) == 3) {
296 /* We know what string it must start with. */
297 while ((s = fbm_instr((unsigned char*)s,
298 (unsigned char*)strend, prog->regstart)) != NULL)
306 c = SvPVX(prog->regstart);
307 while ((s = ninstr(s, strend, c, c + SvCUR(prog->regstart))) != NULL)
317 if (c = prog->regstclass) {
318 I32 doevery = (prog->reganch & ROPT_SKIP) == 0;
321 dontbother = minlen - 1;
322 strend -= dontbother; /* don't bother with what can't match */
324 /* We know what class it must start with. */
330 if (!(c[i >> 3] & (1 << (i&7)))) {
331 if (tmp && regtry(prog, s))
343 dontbother++,strend--;
349 tmp = isALNUM(regprev); /* assume not alphanumeric */
352 if (tmp != isALNUM(i)) {
359 if ((minlen || tmp) && regtry(prog,s))
364 dontbother++,strend--;
370 tmp = isALNUM(regprev); /* assume not alphanumeric */
373 if (tmp != isALNUM(i))
375 else if (regtry(prog, s))
379 if ((minlen || !tmp) && regtry(prog,s))
386 if (tmp && regtry(prog, s))
400 if (tmp && regtry(prog, s))
413 if (tmp && regtry(prog, s))
426 if (tmp && regtry(prog, s))
439 if (tmp && regtry(prog, s))
452 if (tmp && regtry(prog, s))
466 dontbother = minlen - 1;
467 strend -= dontbother;
468 /* We don't know much -- general case. */
472 } while (s++ < strend);
479 strend += dontbother; /* uncheat */
480 prog->subbeg = strbeg;
481 prog->subend = strend;
482 if ((!safebase && (prog->nparens || sawampersand)) || prog->do_folding) {
483 i = strend - startpos + (stringarg - strbeg);
484 if (safebase) { /* no need for $digit later */
488 else if (strbeg != prog->subbase) {
489 s = savepvn(strbeg,i); /* so $digit will work later */
491 Safefree(prog->subbase);
492 prog->subbeg = prog->subbase = s;
496 prog->subbeg = s = prog->subbase;
499 s += (stringarg - strbeg);
500 for (i = 0; i <= prog->nparens; i++) {
502 prog->startp[i] = s + (prog->startp[i] - startpos);
503 prog->endp[i] = s + (prog->endp[i] - startpos);
506 if (prog->do_folding)
512 if (prog->do_folding)
518 - regtry - try match at specific point
520 static I32 /* 0 failure, 1 success */
521 regtry(prog, startpos)
530 regstartp = prog->startp;
531 regendp = prog->endp;
532 reglastparen = &prog->lastparen;
539 for (i = prog->nparens; i >= 0; i--) {
544 if (regmatch(prog->program + 1) && reginput >= regtill) {
545 prog->startp[0] = startpos;
546 prog->endp[0] = reginput;
554 - regmatch - main matching routine
556 * Conceptually the strategy is simple: check to see whether the current
557 * node matches, call self recursively to see whether the rest matches,
558 * and then act accordingly. In practice we make some effort to avoid
559 * recursion, in particular by going through "ordinary" nodes (that don't
560 * need to know whether the rest of the match failed) by a loop instead of
563 /* [lwall] I've hoisted the register declarations to the outer block in order to
564 * maybe save a little bit of pushing and popping on the stack. It also takes
565 * advantage of machines that use a register save mask on subroutine entry.
567 static I32 /* 0 failure, 1 success */
571 register char *scan; /* Current node. */
572 char *next; /* Next node. */
573 register I32 nextchar;
574 register I32 n; /* no or next */
575 register I32 ln; /* len or last */
576 register char *s; /* operand or save */
577 register char *locinput = reginput;
580 nextchar = *locinput;
582 while (scan != NULL) {
585 fprintf(stderr, "%2d%-8.8s\t<%.10s>\n",
586 scan - regprogram, regprop(scan), locinput);
590 next = scan + NEXT(scan);
594 next = regnext(scan);
599 if (locinput == regbol
601 : ((nextchar || locinput < regeol) && locinput[-1] == '\n') )
603 /* regtill = regbol; */
608 if (locinput == regbol
610 : ((nextchar || locinput < regeol) && locinput[-1] == '\n') )
616 if (locinput == regbol && regprev == '\n')
620 if (locinput == regbol)
630 if ((nextchar || locinput < regeol) && nextchar != '\n')
635 if ((nextchar || locinput < regeol) && nextchar != '\n')
637 if (regeol - locinput > 1)
641 if (!nextchar && locinput >= regeol)
643 nextchar = *++locinput;
646 if (!nextchar && locinput >= regeol || nextchar == '\n')
648 nextchar = *++locinput;
653 /* Inline the first character, for speed. */
656 if (regeol - locinput < ln)
658 if (ln > 1 && bcmp(s, locinput, ln) != 0)
661 nextchar = *locinput;
666 nextchar = UCHARAT(locinput);
667 if (s[nextchar >> 3] & (1 << (nextchar&7)))
669 if (!nextchar && locinput >= regeol)
671 nextchar = *++locinput;
676 if (!isALNUM(nextchar))
678 nextchar = *++locinput;
681 if (!nextchar && locinput >= regeol)
683 if (isALNUM(nextchar))
685 nextchar = *++locinput;
689 if (locinput == regbol) /* was last char in word? */
690 ln = isALNUM(regprev);
692 ln = isALNUM(locinput[-1]);
693 n = isALNUM(nextchar); /* is next char in word? */
694 if ((ln == n) == (OP(scan) == BOUND))
698 if (!nextchar && locinput >= regeol)
700 if (!isSPACE(nextchar))
702 nextchar = *++locinput;
707 if (isSPACE(nextchar))
709 nextchar = *++locinput;
712 if (!isDIGIT(nextchar))
714 nextchar = *++locinput;
717 if (!nextchar && locinput >= regeol)
719 if (isDIGIT(nextchar))
721 nextchar = *++locinput;
724 n = ARG1(scan); /* which paren pair */
732 /* Inline the first character, for speed. */
736 if (locinput + ln > regeol)
738 if (ln > 1 && bcmp(s, locinput, ln) != 0)
741 nextchar = *locinput;
749 n = ARG1(scan); /* which paren pair */
750 regstartp[n] = locinput;
755 n = ARG1(scan); /* which paren pair */
756 regendp[n] = locinput;
757 if (n > *reglastparen)
762 CHECKPOINT cp = savestack_ix;
765 cc.parenfloor = *reglastparen;
769 cc.scan = NEXTOPER(scan) + 4;
774 n = regmatch(PREVOPER(next)); /* start on the WHILEM */
782 * This is really hard to understand, because after we match
783 * what we're trying to match, we must make sure the rest of
784 * the RE is going to match for sure, and to do that we have
785 * to go back UP the parse tree by recursing ever deeper. And
786 * if it fails, we have to reset our parent's current state
787 * that we can try again after backing off.
794 /* If degenerate scan matches "", assume scan done. */
796 if (locinput == cc->lastloc) {
799 if (regmatch(cc->next))
806 /* First just match a string of min scans. */
810 cc->lastloc = locinput;
811 return regmatch(cc->scan);
814 /* Prefer next over scan for minimal matching. */
819 if (regmatch(cc->next))
820 return TRUE; /* All done. */
824 if (n >= cc->max) /* Maximum greed exceeded? */
827 /* Try scanning more and see if it helps. */
830 cc->lastloc = locinput;
831 return regmatch(cc->scan);
834 /* Prefer scan over next for maximal matching. */
836 if (n < cc->max) { /* More greed allowed? */
837 regcppush(cc->parenfloor);
839 cc->lastloc = locinput;
840 if (regmatch(cc->scan))
842 regcppop(); /* Restore some previous $<digit>s? */
846 /* Failed deeper matches of scan, so see if this one works. */
849 if (regmatch(cc->next))
857 if (OP(next) != BRANCH) /* No choice. */
858 next = NEXTOPER(scan);/* Avoid recursion. */
860 int lastparen = *reglastparen;
863 if (regmatch(NEXTOPER(scan)))
865 for (n = *reglastparen; n > lastparen; n--)
876 scan = regnext(scan);
878 } while (scan != NULL && OP(scan) == BRANCH);
888 ln = ARG1(scan); /* min to match */
889 n = ARG2(scan); /* max to match */
890 scan = NEXTOPER(scan) + 4;
895 scan = NEXTOPER(scan);
899 * Lookahead to avoid useless match attempts
900 * when we know what character comes next.
904 scan = NEXTOPER(scan);
906 if (OP(next) == EXACTLY)
907 nextchar = *(OPERAND(next)+1);
913 if (ln && regrepeat(scan, ln) < ln)
915 while (n >= ln || (n == 32767 && ln > 0)) { /* ln overflow ? */
916 /* If it could work, try it. */
917 if (nextchar == -1000 || *reginput == nextchar)
920 /* Couldn't or didn't -- back up. */
921 reginput = locinput + ln;
922 if (regrepeat(scan, 1)) {
924 reginput = locinput + ln;
931 n = regrepeat(scan, n);
932 if (ln < n && regkind[(U8)OP(next)] == EOL &&
933 (!multiline || OP(next) == SEOL))
934 ln = n; /* why back off? */
936 /* If it could work, try it. */
937 if (nextchar == -1000 || *reginput == nextchar)
940 /* Couldn't or didn't -- back up. */
942 reginput = locinput + n;
948 reginput = locinput; /* put where regtry can find it */
949 return 1; /* Success! */
952 scan = NEXTOPER(scan);
958 scan = NEXTOPER(scan);
963 fprintf(stderr, "%x %d\n",(unsigned)scan,scan[1]);
964 FAIL("regexp memory corruption");
970 * We get here only if there's trouble -- normally "case END" is
971 * the terminating point.
973 FAIL("corrupted regexp pointers");
979 - regrepeat - repeatedly match something simple, report how many
982 * [This routine now assumes that it will only match on things of length 1.
983 * That was true before, but now we assume scan - reginput is the count,
984 * rather than incrementing count on every character.]
994 register char *loceol = regeol;
997 if (max != 32767 && max < loceol - scan)
1002 while (scan < loceol && *scan != '\n')
1008 case EXACTLY: /* length of string is 1 */
1010 while (scan < loceol && *opnd == *scan)
1015 while (scan < loceol && !(opnd[c >> 3] & (1 << (c & 7)))) {
1021 while (scan < loceol && isALNUM(*scan))
1025 while (scan < loceol && !isALNUM(*scan))
1029 while (scan < loceol && isSPACE(*scan))
1033 while (scan < loceol && !isSPACE(*scan))
1037 while (scan < loceol && isDIGIT(*scan))
1041 while (scan < loceol && !isDIGIT(*scan))
1044 default: /* Called on something of 0 width. */
1045 break; /* So match right here or not at all. */
1048 c = scan - reginput;
1055 - regnext - dig the "next" pointer out of a node
1057 * [Note, when REGALIGN is defined there are two places in regmatch()
1058 * that bypass this code for speed.]
1064 register I32 offset;