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 static CHECKPOINT regcppush _((I32 parenfloor));
86 static 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));
150 static bool reginclass _((char *p, I32 c));
152 static bool regtainted; /* tainted information used? */
155 - pregexec - match a regexp against a string
158 pregexec(prog, stringarg, strend, strbeg, minend, screamer, safebase)
159 register regexp *prog;
161 register char *strend; /* pointer to null at end of string */
162 char *strbeg; /* real beginning of string */
163 I32 minend; /* end of match must be at least minend after stringarg */
165 I32 safebase; /* no need to remember string in subbase */
169 register char *startpos = stringarg;
171 I32 minlen = 0; /* must match at least this many chars */
172 I32 dontbother = 0; /* how many characters not to try at end */
180 regnarrate = debug & 512;
181 regprogram = prog->program;
185 if (prog == NULL || startpos == NULL) {
186 croak("NULL regexp parameter");
190 if (startpos == strbeg) /* is ^ valid at stringarg? */
193 regprev = stringarg[-1];
194 if (!multiline && regprev == '\n')
195 regprev = '\0'; /* force ^ to NOT match */
198 regprecomp = prog->precomp;
199 /* Check validity of program. */
200 if (UCHARAT(prog->program) != MAGIC) {
201 FAIL("corrupted regexp program");
204 regnpar = prog->nparens;
207 /* If there is a "must appear" string, look for it. */
209 if (prog->regmust != Nullsv &&
210 (!(prog->reganch & ROPT_ANCH)
211 || (multiline && prog->regback >= 0)) )
213 if (stringarg == strbeg && screamer) {
214 if (screamfirst[BmRARE(prog->regmust)] >= 0)
215 s = screaminstr(screamer,prog->regmust);
220 s = fbm_instr((unsigned char*)s, (unsigned char*)strend,
223 ++BmUSEFUL(prog->regmust); /* hooray */
224 goto phooey; /* not present */
226 else if (prog->regback >= 0) {
230 minlen = prog->regback + SvCUR(prog->regmust);
232 else if (!prog->naughty && --BmUSEFUL(prog->regmust) < 0) { /* boo */
233 SvREFCNT_dec(prog->regmust);
234 prog->regmust = Nullsv; /* disable regmust */
239 minlen = SvCUR(prog->regmust);
243 /* Mark beginning of line for ^ . */
246 /* Mark end of line for $ (and such) */
249 /* see how far we have to get to not match where we matched before */
250 regtill = startpos+minend;
252 /* Simplest case: anchored match need be tried only once. */
253 /* [unless multiline is set] */
254 if (prog->reganch & ROPT_ANCH) {
255 if (regtry(prog, startpos))
257 else if (multiline || (prog->reganch & ROPT_IMPLICIT)) {
259 dontbother = minlen - 1;
260 strend -= dontbother;
261 /* for multiline we only have to try after newlines */
266 if (s < strend && regtry(prog, s))
274 /* Messy cases: unanchored match. */
275 if (prog->regstart) {
276 if (prog->reganch & ROPT_SKIP) { /* we have /x+whatever/ */
277 /* it must be a one character string */
278 char ch = SvPVX(prog->regstart)[0];
284 while (s < strend && *s == ch)
290 else if (SvPOK(prog->regstart) == 3) {
291 /* We know what string it must start with. */
292 while ((s = fbm_instr((unsigned char*)s,
293 (unsigned char*)strend, prog->regstart)) != NULL)
301 c = SvPVX(prog->regstart);
302 while ((s = ninstr(s, strend, c, c + SvCUR(prog->regstart))) != NULL)
312 if (c = prog->regstclass) {
313 I32 doevery = (prog->reganch & ROPT_SKIP) == 0;
316 dontbother = minlen - 1;
317 strend -= dontbother; /* don't bother with what can't match */
319 /* We know what class it must start with. */
324 if (reginclass(c, *s)) {
325 if (tmp && regtry(prog, s))
340 dontbother++,strend--;
341 tmp = (s != startpos) ? UCHARAT(s - 1) : regprev;
342 tmp = ((OP(c) == BOUND ? isALNUM(tmp) : isALNUM_LC(tmp)) != 0);
344 if (tmp == !(OP(c) == BOUND ? isALNUM(*s) : isALNUM_LC(*s))) {
351 if ((minlen || tmp) && regtry(prog,s))
359 dontbother++,strend--;
360 tmp = (s != startpos) ? UCHARAT(s - 1) : regprev;
361 tmp = ((OP(c) == NBOUND ? isALNUM(tmp) : isALNUM_LC(tmp)) != 0);
363 if (tmp == !(OP(c) == NBOUND ? isALNUM(*s) : isALNUM_LC(*s)))
365 else if (regtry(prog, s))
369 if ((minlen || !tmp) && regtry(prog,s))
375 if (tmp && regtry(prog, s))
388 if (isALNUM_LC(*s)) {
389 if (tmp && regtry(prog, s))
402 if (tmp && regtry(prog, s))
415 if (!isALNUM_LC(*s)) {
416 if (tmp && regtry(prog, s))
429 if (tmp && regtry(prog, s))
442 if (isSPACE_LC(*s)) {
443 if (tmp && regtry(prog, s))
456 if (tmp && regtry(prog, s))
469 if (!isSPACE_LC(*s)) {
470 if (tmp && regtry(prog, s))
483 if (tmp && regtry(prog, s))
496 if (tmp && regtry(prog, s))
510 dontbother = minlen - 1;
511 strend -= dontbother;
512 /* We don't know much -- general case. */
516 } while (s++ < strend);
523 strend += dontbother; /* uncheat */
524 prog->subbeg = strbeg;
525 prog->subend = strend;
526 prog->exec_tainted = regtainted;
528 /* make sure $`, $&, $', and $digit will work later */
529 if (!safebase && (strbeg != prog->subbase)) {
530 I32 i = strend - startpos + (stringarg - strbeg);
531 s = savepvn(strbeg, i);
532 Safefree(prog->subbase);
534 prog->subbeg = prog->subbase;
535 prog->subend = prog->subbase + i;
536 s = prog->subbase + (stringarg - strbeg);
537 for (i = 0; i <= prog->nparens; i++) {
539 prog->startp[i] = s + (prog->startp[i] - startpos);
540 prog->endp[i] = s + (prog->endp[i] - startpos);
551 - regtry - try match at specific point
553 static I32 /* 0 failure, 1 success */
554 regtry(prog, startpos)
563 regstartp = prog->startp;
564 regendp = prog->endp;
565 reglastparen = &prog->lastparen;
572 for (i = prog->nparens; i >= 0; i--) {
577 if (regmatch(prog->program + 1) && reginput >= regtill) {
578 prog->startp[0] = startpos;
579 prog->endp[0] = reginput;
587 - regmatch - main matching routine
589 * Conceptually the strategy is simple: check to see whether the current
590 * node matches, call self recursively to see whether the rest matches,
591 * and then act accordingly. In practice we make some effort to avoid
592 * recursion, in particular by going through "ordinary" nodes (that don't
593 * need to know whether the rest of the match failed) by a loop instead of
596 /* [lwall] I've hoisted the register declarations to the outer block in order to
597 * maybe save a little bit of pushing and popping on the stack. It also takes
598 * advantage of machines that use a register save mask on subroutine entry.
600 static I32 /* 0 failure, 1 success */
604 register char *scan; /* Current node. */
605 char *next; /* Next node. */
606 register I32 nextchar;
607 register I32 n; /* no or next */
608 register I32 ln; /* len or last */
609 register char *s; /* operand or save */
610 register char *locinput = reginput;
611 register I32 c1, c2; /* case fold search */
614 static int regindent = 0;
618 nextchar = UCHARAT(locinput);
620 while (scan != NULL) {
622 #define sayYES goto yes
623 #define sayNO goto no
624 #define saySAME(x) if (x) goto yes; else goto no
626 PerlIO_printf(Perl_debug_log, "%*s%2d%-8.8s\t<%.10s>\n", regindent*2, "",
627 scan - regprogram, regprop(scan), locinput);
630 #define sayYES return 1
631 #define sayNO return 0
632 #define saySAME(x) return x
636 next = scan + NEXT(scan);
640 next = regnext(scan);
645 if (locinput == regbol
647 : ((nextchar || locinput < regeol) && locinput[-1] == '\n') )
649 /* regtill = regbol; */
654 if (locinput == regbol
656 : ((nextchar || locinput < regeol) && locinput[-1] == '\n') )
662 if (locinput == regbol && regprev == '\n')
666 if (locinput == regbol)
676 if ((nextchar || locinput < regeol) && nextchar != '\n')
681 if ((nextchar || locinput < regeol) && nextchar != '\n')
683 if (regeol - locinput > 1)
687 if (!nextchar && locinput >= regeol)
689 nextchar = UCHARAT(++locinput);
692 if (!nextchar && locinput >= regeol || nextchar == '\n')
694 nextchar = UCHARAT(++locinput);
699 /* Inline the first character, for speed. */
700 if (UCHARAT(s) != nextchar)
702 if (regeol - locinput < ln)
704 if (ln > 1 && memNE(s, locinput, ln))
707 nextchar = UCHARAT(locinput);
715 /* Inline the first character, for speed. */
716 if (UCHARAT(s) != nextchar &&
717 UCHARAT(s) != ((OP(scan) == EXACTF)
718 ? fold : fold_locale)[nextchar])
720 if (regeol - locinput < ln)
722 if (ln > 1 && (OP(scan) == EXACTF
723 ? ibcmp(s, locinput, ln)
724 : ibcmp_locale(s, locinput, ln)))
727 nextchar = UCHARAT(locinput);
732 nextchar = UCHARAT(locinput);
733 if (!reginclass(s, nextchar))
735 if (!nextchar && locinput >= regeol)
737 nextchar = UCHARAT(++locinput);
745 if (!(OP(scan) == ALNUM
746 ? isALNUM(nextchar) : isALNUM_LC(nextchar)))
748 nextchar = UCHARAT(++locinput);
754 if (!nextchar && locinput >= regeol)
756 if (OP(scan) == NALNUM
757 ? isALNUM(nextchar) : isALNUM_LC(nextchar))
759 nextchar = UCHARAT(++locinput);
767 /* was last char in word? */
768 ln = (locinput != regbol) ? UCHARAT(locinput - 1) : regprev;
769 if (OP(scan) == BOUND || OP(scan) == NBOUND) {
771 n = isALNUM(nextchar);
775 n = isALNUM_LC(nextchar);
777 if (((!ln) == (!n)) == (OP(scan) == BOUND || OP(scan) == BOUNDL))
784 if (!nextchar && locinput >= regeol)
786 if (!(OP(scan) == SPACE
787 ? isSPACE(nextchar) : isSPACE_LC(nextchar)))
789 nextchar = UCHARAT(++locinput);
797 if (OP(scan) == SPACE
798 ? isSPACE(nextchar) : isSPACE_LC(nextchar))
800 nextchar = UCHARAT(++locinput);
803 if (!isDIGIT(nextchar))
805 nextchar = UCHARAT(++locinput);
808 if (!nextchar && locinput >= regeol)
810 if (isDIGIT(nextchar))
812 nextchar = UCHARAT(++locinput);
815 n = ARG1(scan); /* which paren pair */
823 /* Inline the first character, for speed. */
824 if (UCHARAT(s) != nextchar)
827 if (locinput + ln > regeol)
829 if (ln > 1 && memNE(s, locinput, ln))
832 nextchar = UCHARAT(locinput);
840 n = ARG1(scan); /* which paren pair */
841 regstartp[n] = locinput;
846 n = ARG1(scan); /* which paren pair */
847 regendp[n] = locinput;
848 if (n > *reglastparen)
853 CHECKPOINT cp = savestack_ix;
856 cc.parenfloor = *reglastparen;
860 cc.scan = NEXTOPER(scan) + 4;
865 n = regmatch(PREVOPER(next)); /* start on the WHILEM */
873 * This is really hard to understand, because after we match
874 * what we're trying to match, we must make sure the rest of
875 * the RE is going to match for sure, and to do that we have
876 * to go back UP the parse tree by recursing ever deeper. And
877 * if it fails, we have to reset our parent's current state
878 * that we can try again after backing off.
883 n = cc->cur + 1; /* how many we know we matched */
888 PerlIO_printf(Perl_debug_log, "%*s %d %lx\n", regindent*2, "",
892 /* If degenerate scan matches "", assume scan done. */
894 if (locinput == cc->lastloc && n >= cc->min) {
897 if (regmatch(cc->next))
904 /* First just match a string of min scans. */
908 cc->lastloc = locinput;
909 if (regmatch(cc->scan))
915 /* Prefer next over scan for minimal matching. */
920 cp = regcppush(cc->parenfloor);
921 if (regmatch(cc->next)) {
923 sayYES; /* All done. */
929 if (n >= cc->max) /* Maximum greed exceeded? */
932 /* Try scanning more and see if it helps. */
935 cc->lastloc = locinput;
936 cp = regcppush(cc->parenfloor);
937 if (regmatch(cc->scan)) {
946 /* Prefer scan over next for maximal matching. */
948 if (n < cc->max) { /* More greed allowed? */
949 cp = regcppush(cc->parenfloor);
951 cc->lastloc = locinput;
952 if (regmatch(cc->scan)) {
956 regcppop(); /* Restore some previous $<digit>s? */
960 /* Failed deeper matches of scan, so see if this one works. */
963 if (regmatch(cc->next))
972 if (OP(next) != BRANCH) /* No choice. */
973 next = NEXTOPER(scan);/* Avoid recursion. */
975 int lastparen = *reglastparen;
978 if (regmatch(NEXTOPER(scan)))
980 for (n = *reglastparen; n > lastparen; n--)
991 scan = regnext(scan);
993 } while (scan != NULL && OP(scan) == BRANCH);
1003 ln = ARG1(scan); /* min to match */
1004 n = ARG2(scan); /* max to match */
1005 scan = NEXTOPER(scan) + 4;
1010 scan = NEXTOPER(scan);
1014 * Lookahead to avoid useless match attempts
1015 * when we know what character comes next.
1019 scan = NEXTOPER(scan);
1021 if (regkind[(U8)OP(next)] == EXACT) {
1022 c1 = UCHARAT(OPERAND(next) + 1);
1023 if (OP(next) == EXACTF)
1025 else if (OP(next) == EXACTFL)
1026 c2 = fold_locale[c1];
1032 reginput = locinput;
1035 if (ln && regrepeat(scan, ln) < ln)
1037 while (n >= ln || (n == 32767 && ln > 0)) { /* ln overflow ? */
1038 /* If it could work, try it. */
1040 UCHARAT(reginput) == c1 ||
1041 UCHARAT(reginput) == c2)
1046 /* Couldn't or didn't -- back up. */
1047 reginput = locinput + ln;
1048 if (regrepeat(scan, 1)) {
1050 reginput = locinput + ln;
1057 n = regrepeat(scan, n);
1058 if (ln < n && regkind[(U8)OP(next)] == EOL &&
1059 (!multiline || OP(next) == SEOL))
1060 ln = n; /* why back off? */
1062 /* If it could work, try it. */
1064 UCHARAT(reginput) == c1 ||
1065 UCHARAT(reginput) == c2)
1070 /* Couldn't or didn't -- back up. */
1072 reginput = locinput + n;
1078 reginput = locinput; /* put where regtry can find it */
1079 sayYES; /* Success! */
1081 reginput = locinput;
1082 scan = NEXTOPER(scan);
1083 if (!regmatch(scan))
1087 reginput = locinput;
1088 scan = NEXTOPER(scan);
1093 PerlIO_printf(PerlIO_stderr(), "%x %d\n",(unsigned)scan,scan[1]);
1094 FAIL("regexp memory corruption");
1100 * We get here only if there's trouble -- normally "case END" is
1101 * the terminating point.
1103 FAIL("corrupted regexp pointers");
1121 - regrepeat - repeatedly match something simple, report how many
1124 * [This routine now assumes that it will only match on things of length 1.
1125 * That was true before, but now we assume scan - reginput is the count,
1126 * rather than incrementing count on every character.]
1133 register char *scan;
1134 register char *opnd;
1136 register char *loceol = regeol;
1139 if (max != 32767 && max < loceol - scan)
1140 loceol = scan + max;
1144 while (scan < loceol && *scan != '\n')
1150 case EXACT: /* length of string is 1 */
1151 c = UCHARAT(++opnd);
1152 while (scan < loceol && UCHARAT(scan) == c)
1155 case EXACTF: /* length of string is 1 */
1156 c = UCHARAT(++opnd);
1157 while (scan < loceol &&
1158 (UCHARAT(scan) == c || UCHARAT(scan) == fold[c]))
1161 case EXACTFL: /* length of string is 1 */
1163 c = UCHARAT(++opnd);
1164 while (scan < loceol &&
1165 (UCHARAT(scan) == c || UCHARAT(scan) == fold_locale[c]))
1169 while (scan < loceol && reginclass(opnd, *scan))
1173 while (scan < loceol && isALNUM(*scan))
1178 while (scan < loceol && isALNUM_LC(*scan))
1182 while (scan < loceol && !isALNUM(*scan))
1187 while (scan < loceol && !isALNUM_LC(*scan))
1191 while (scan < loceol && isSPACE(*scan))
1196 while (scan < loceol && isSPACE_LC(*scan))
1200 while (scan < loceol && !isSPACE(*scan))
1205 while (scan < loceol && !isSPACE_LC(*scan))
1209 while (scan < loceol && isDIGIT(*scan))
1213 while (scan < loceol && !isDIGIT(*scan))
1216 default: /* Called on something of 0 width. */
1217 break; /* So match right here or not at all. */
1220 c = scan - reginput;
1227 - regclass - determine if a character falls into a character class
1239 if (p[1 + (c >> 3)] & (1 << (c & 7)))
1241 else if (flags & ANYOF_FOLD) {
1243 if (flags & ANYOF_LOCALE) {
1245 cf = fold_locale[c];
1249 if (p[1 + (cf >> 3)] & (1 << (cf & 7)))
1253 if (!match && (flags & ANYOF_ISA)) {
1256 if (((flags & ANYOF_ALNUML) && isALNUM_LC(c)) ||
1257 ((flags & ANYOF_NALNUML) && !isALNUM_LC(c)) ||
1258 ((flags & ANYOF_SPACEL) && isSPACE_LC(c)) ||
1259 ((flags & ANYOF_NSPACEL) && !isSPACE_LC(c)))
1265 return match ^ ((flags & ANYOF_INVERT) != 0);
1269 - regnext - dig the "next" pointer out of a node
1271 * [Note, when REGALIGN is defined there are two places in regmatch()
1272 * that bypass this code for speed.]
1278 register I32 offset;