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+/* NOTE: this is derived from Henry Spencer's regexp code, and should not
+ * confused with the original package (see point 3 below). Thanks, Henry!
+ */
+
+/* Additional note: this code is very heavily munged from Henry's version
+ * in places. In some spots I've traded clarity for efficiency, so don't
+ * blame Henry for some of the lack of readability.
+ */
+
+/* $Header: regexec.c,v 3.0 89/10/18 15:22:53 lwall Locked $
+ *
+ * $Log: regexec.c,v $
+ * Revision 3.0 89/10/18 15:22:53 lwall
+ * 3.0 baseline
+ *
+ */
+
+/*
+ * regcomp and regexec -- regsub and regerror are not used in perl
+ *
+ * Copyright (c) 1986 by University of Toronto.
+ * Written by Henry Spencer. Not derived from licensed software.
+ *
+ * Permission is granted to anyone to use this software for any
+ * purpose on any computer system, and to redistribute it freely,
+ * subject to the following restrictions:
+ *
+ * 1. The author is not responsible for the consequences of use of
+ * this software, no matter how awful, even if they arise
+ * from defects in it.
+ *
+ * 2. The origin of this software must not be misrepresented, either
+ * by explicit claim or by omission.
+ *
+ * 3. Altered versions must be plainly marked as such, and must not
+ * be misrepresented as being the original software.
+ *
+ **** Alterations to Henry's code are...
+ ****
+ **** Copyright (c) 1989, Larry Wall
+ ****
+ **** You may distribute under the terms of the GNU General Public License
+ **** as specified in the README file that comes with the perl 3.0 kit.
+ *
+ * Beware that some of this code is subtly aware of the way operator
+ * precedence is structured in regular expressions. Serious changes in
+ * regular-expression syntax might require a total rethink.
+ */
+#include "EXTERN.h"
+#include "perl.h"
+#include "regcomp.h"
+
+#ifndef STATIC
+#define STATIC static
+#endif
+
+#ifdef DEBUGGING
+int regnarrate = 0;
+#endif
+
+/*
+ * regexec and friends
+ */
+
+/*
+ * Global work variables for regexec().
+ */
+static char *regprecomp;
+static char *reginput; /* String-input pointer. */
+static char *regbol; /* Beginning of input, for ^ check. */
+static char *regeol; /* End of input, for $ check. */
+static char **regstartp; /* Pointer to startp array. */
+static char **regendp; /* Ditto for endp. */
+static char *reglastparen; /* Similarly for lastparen. */
+static char *regtill;
+
+static char *regmystartp[10]; /* For remembering backreferences. */
+static char *regmyendp[10];
+
+/*
+ * Forwards.
+ */
+STATIC int regtry();
+STATIC int regmatch();
+STATIC int regrepeat();
+
+extern int multiline;
+
+/*
+ - regexec - match a regexp against a string
+ */
+int
+regexec(prog, stringarg, strend, strbeg, minend, screamer, safebase)
+register regexp *prog;
+char *stringarg;
+register char *strend; /* pointer to null at end of string */
+char *strbeg; /* real beginning of string */
+int minend; /* end of match must be at least minend after stringarg */
+STR *screamer;
+int safebase; /* no need to remember string in subbase */
+{
+ register char *s;
+ register int i;
+ register char *c;
+ register char *string = stringarg;
+ register int tmp;
+ int minlen = 0; /* must match at least this many chars */
+ int dontbother = 0; /* how many characters not to try at end */
+ int beginning = (string == strbeg); /* is ^ valid at stringarg? */
+
+ /* Be paranoid... */
+ if (prog == NULL || string == NULL) {
+ fatal("NULL regexp parameter");
+ return(0);
+ }
+
+ regprecomp = prog->precomp;
+ /* Check validity of program. */
+ if (UCHARAT(prog->program) != MAGIC) {
+ FAIL("corrupted regexp program");
+ }
+
+ if (prog->do_folding) {
+ safebase = FALSE;
+ i = strend - string;
+ New(1101,c,i+1,char);
+ (void)bcopy(string, c, i+1);
+ string = c;
+ strend = string + i;
+ for (s = string; s < strend; s++)
+ if (isupper(*s))
+ *s = tolower(*s);
+ }
+
+ /* If there is a "must appear" string, look for it. */
+ s = string;
+ if (prog->regmust != Nullstr) {
+ if (beginning && screamer) {
+ if (screamfirst[prog->regmust->str_rare] >= 0)
+ s = screaminstr(screamer,prog->regmust);
+ else
+ s = Nullch;
+ }
+#ifndef lint
+ else
+ s = fbminstr((unsigned char*)s, (unsigned char*)strend,
+ prog->regmust);
+#endif
+ if (!s) {
+ ++prog->regmust->str_u.str_useful; /* hooray */
+ goto phooey; /* not present */
+ }
+ else if (prog->regback >= 0) {
+ s -= prog->regback;
+ if (s < string)
+ s = string;
+ minlen = prog->regback + prog->regmust->str_cur;
+ }
+ else if (--prog->regmust->str_u.str_useful < 0) { /* boo */
+ str_free(prog->regmust);
+ prog->regmust = Nullstr; /* disable regmust */
+ s = string;
+ }
+ else {
+ s = string;
+ minlen = prog->regmust->str_cur;
+ }
+ }
+
+ /* Mark beginning of line for ^ . */
+ if (beginning)
+ regbol = string;
+ else
+ regbol = NULL;
+
+ /* Mark end of line for $ (and such) */
+ regeol = strend;
+
+ /* see how far we have to get to not match where we matched before */
+ regtill = string+minend;
+
+ /* Simplest case: anchored match need be tried only once. */
+ /* [unless multiline is set] */
+ if (prog->reganch) {
+ if (regtry(prog, string))
+ goto got_it;
+ else if (multiline) {
+ if (minlen)
+ dontbother = minlen - 1;
+ strend -= dontbother;
+ /* for multiline we only have to try after newlines */
+ if (s > string)
+ s--;
+ for (; s < strend; s++) {
+ if (*s == '\n') {
+ if (++s < strend && regtry(prog, s))
+ goto got_it;
+ }
+ }
+ }
+ goto phooey;
+ }
+
+ /* Messy cases: unanchored match. */
+ if (prog->regstart) {
+ /* We know what string it must start with. */
+ if (prog->regstart->str_pok == 3) {
+#ifndef lint
+ while ((s = fbminstr((unsigned char*)s,
+ (unsigned char*)strend, prog->regstart)) != NULL)
+#else
+ while (s = Nullch)
+#endif
+ {
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ }
+ else {
+ c = prog->regstart->str_ptr;
+ while ((s = ninstr(s, strend,
+ c, c + prog->regstart->str_cur )) != NULL) {
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ }
+ goto phooey;
+ }
+ if (c = prog->regstclass) {
+ if (minlen)
+ dontbother = minlen - 1;
+ strend -= dontbother; /* don't bother with what can't match */
+ /* We know what class it must start with. */
+ switch (OP(c)) {
+ case ANYOF: case ANYBUT:
+ c = OPERAND(c);
+ while (s < strend) {
+ i = *s;
+ if (!(c[i >> 3] & (1 << (i&7))))
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ break;
+ case BOUND:
+ if (minlen)
+ dontbother++,strend--;
+ if (s != string) {
+ i = s[-1];
+ tmp = (isalpha(i) || isdigit(i) || i == '_');
+ }
+ else
+ tmp = 0; /* assume not alphanumeric */
+ while (s < strend) {
+ i = *s;
+ if (tmp != (isalpha(i) || isdigit(i) || i == '_')) {
+ tmp = !tmp;
+ if (regtry(prog, s))
+ goto got_it;
+ }
+ s++;
+ }
+ if (tmp && regtry(prog,s))
+ goto got_it;
+ break;
+ case NBOUND:
+ if (minlen)
+ dontbother++,strend--;
+ if (s != string) {
+ i = s[-1];
+ tmp = (isalpha(i) || isdigit(i) || i == '_');
+ }
+ else
+ tmp = 0; /* assume not alphanumeric */
+ while (s < strend) {
+ i = *s;
+ if (tmp != (isalpha(i) || isdigit(i) || i == '_'))
+ tmp = !tmp;
+ else if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ if (!tmp && regtry(prog,s))
+ goto got_it;
+ break;
+ case ALNUM:
+ while (s < strend) {
+ i = *s;
+ if (isalpha(i) || isdigit(i) || i == '_')
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ break;
+ case NALNUM:
+ while (s < strend) {
+ i = *s;
+ if (!isalpha(i) && !isdigit(i) && i != '_')
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ break;
+ case SPACE:
+ while (s < strend) {
+ if (isspace(*s))
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ break;
+ case NSPACE:
+ while (s < strend) {
+ if (!isspace(*s))
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ break;
+ case DIGIT:
+ while (s < strend) {
+ if (isdigit(*s))
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ break;
+ case NDIGIT:
+ while (s < strend) {
+ if (!isdigit(*s))
+ if (regtry(prog, s))
+ goto got_it;
+ s++;
+ }
+ break;
+ }
+ }
+ else {
+ dontbother = minend;
+ strend -= dontbother;
+ /* We don't know much -- general case. */
+ do {
+ if (regtry(prog, s))
+ goto got_it;
+ } while (s++ < strend);
+ }
+
+ /* Failure. */
+ goto phooey;
+
+ got_it:
+ if ((!safebase && (prog->nparens || sawampersand)) || prog->do_folding){
+ strend += dontbother; /* uncheat */
+ if (safebase) /* no need for $digit later */
+ s = strbeg;
+ else if (strbeg != prog->subbase) {
+ i = strend - string + (stringarg - strbeg);
+ s = nsavestr(strbeg,i); /* so $digit will work later */
+ if (prog->subbase)
+ Safefree(prog->subbase);
+ prog->subbase = s;
+ }
+ else
+ s = prog->subbase;
+ s += (stringarg - strbeg);
+ for (i = 0; i <= prog->nparens; i++) {
+ if (prog->endp[i]) {
+ prog->startp[i] = s + (prog->startp[i] - string);
+ prog->endp[i] = s + (prog->endp[i] - string);
+ }
+ }
+ if (prog->do_folding)
+ Safefree(string);
+ }
+ return(1);
+
+ phooey:
+ if (prog->do_folding)
+ Safefree(string);
+ return(0);
+}
+
+/*
+ - regtry - try match at specific point
+ */
+static int /* 0 failure, 1 success */
+regtry(prog, string)
+regexp *prog;
+char *string;
+{
+ register int i;
+ register char **sp;
+ register char **ep;
+
+ reginput = string;
+ regstartp = prog->startp;
+ regendp = prog->endp;
+ reglastparen = &prog->lastparen;
+ prog->lastparen = 0;
+
+ sp = prog->startp;
+ ep = prog->endp;
+ if (prog->nparens) {
+ for (i = NSUBEXP; i > 0; i--) {
+ *sp++ = NULL;
+ *ep++ = NULL;
+ }
+ }
+ if (regmatch(prog->program + 1) && reginput >= regtill) {
+ prog->startp[0] = string;
+ prog->endp[0] = reginput;
+ return(1);
+ } else
+ return(0);
+}
+
+/*
+ - regmatch - main matching routine
+ *
+ * Conceptually the strategy is simple: check to see whether the current
+ * node matches, call self recursively to see whether the rest matches,
+ * and then act accordingly. In practice we make some effort to avoid
+ * recursion, in particular by going through "ordinary" nodes (that don't
+ * need to know whether the rest of the match failed) by a loop instead of
+ * by recursion.
+ */
+/* [lwall] I've hoisted the register declarations to the outer block in order to
+ * maybe save a little bit of pushing and popping on the stack. It also takes
+ * advantage of machines that use a register save mask on subroutine entry.
+ */
+static int /* 0 failure, 1 success */
+regmatch(prog)
+char *prog;
+{
+ register char *scan; /* Current node. */
+ char *next; /* Next node. */
+ register int nextchar;
+ register int n; /* no or next */
+ register int ln; /* len or last */
+ register char *s; /* operand or save */
+ register char *locinput = reginput;
+
+ nextchar = *locinput;
+ scan = prog;
+#ifdef DEBUGGING
+ if (scan != NULL && regnarrate)
+ fprintf(stderr, "%s(\n", regprop(scan));
+#endif
+ while (scan != NULL) {
+#ifdef DEBUGGING
+ if (regnarrate)
+ fprintf(stderr, "%s...\n", regprop(scan));
+#endif
+
+#ifdef REGALIGN
+ next = scan + NEXT(scan);
+ if (next == scan)
+ next = NULL;
+#else
+ next = regnext(scan);
+#endif
+
+ switch (OP(scan)) {
+ case BOL:
+ if (locinput == regbol ||
+ ((nextchar || locinput < regeol) &&
+ locinput[-1] == '\n') )
+ {
+ regtill--;
+ break;
+ }
+ return(0);
+ case EOL:
+ if ((nextchar || locinput < regeol) && nextchar != '\n')
+ return(0);
+ regtill--;
+ break;
+ case ANY:
+ if ((nextchar == '\0' && locinput >= regeol) ||
+ nextchar == '\n')
+ return(0);
+ nextchar = *++locinput;
+ break;
+ case EXACTLY:
+ s = OPERAND(scan);
+ ln = *s++;
+ /* Inline the first character, for speed. */
+ if (*s != nextchar)
+ return(0);
+ if (locinput + ln > regeol)
+ return 0;
+ if (ln > 1 && bcmp(s, locinput, ln) != 0)
+ return(0);
+ locinput += ln;
+ nextchar = *locinput;
+ break;
+ case ANYOF:
+ case ANYBUT:
+ s = OPERAND(scan);
+ if (nextchar < 0)
+ nextchar = UCHARAT(locinput);
+ if (s[nextchar >> 3] & (1 << (nextchar&7)))
+ return(0);
+ nextchar = *++locinput;
+ if (!nextchar && locinput > regeol)
+ return 0;
+ break;
+ case ALNUM:
+ if (!nextchar)
+ return(0);
+ if (!isalpha(nextchar) && !isdigit(nextchar) &&
+ nextchar != '_')
+ return(0);
+ nextchar = *++locinput;
+ break;
+ case NALNUM:
+ if (!nextchar && locinput >= regeol)
+ return(0);
+ if (isalpha(nextchar) || isdigit(nextchar) ||
+ nextchar == '_')
+ return(0);
+ nextchar = *++locinput;
+ break;
+ case NBOUND:
+ case BOUND:
+ if (locinput == regbol) /* was last char in word? */
+ ln = 0;
+ else
+ ln = (isalpha(locinput[-1]) ||
+ isdigit(locinput[-1]) ||
+ locinput[-1] == '_' );
+ n = (isalpha(nextchar) || isdigit(nextchar) ||
+ nextchar == '_' ); /* is next char in word? */
+ if ((ln == n) == (OP(scan) == BOUND))
+ return(0);
+ break;
+ case SPACE:
+ if (!nextchar && locinput >= regeol)
+ return(0);
+ if (!isspace(nextchar))
+ return(0);
+ nextchar = *++locinput;
+ break;
+ case NSPACE:
+ if (!nextchar)
+ return(0);
+ if (isspace(nextchar))
+ return(0);
+ nextchar = *++locinput;
+ break;
+ case DIGIT:
+ if (!isdigit(nextchar))
+ return(0);
+ nextchar = *++locinput;
+ break;
+ case NDIGIT:
+ if (!nextchar && locinput >= regeol)
+ return(0);
+ if (isdigit(nextchar))
+ return(0);
+ nextchar = *++locinput;
+ break;
+ case REF:
+ case REF+1:
+ case REF+2:
+ case REF+3:
+ case REF+4:
+ case REF+5:
+ case REF+6:
+ case REF+7:
+ case REF+8:
+ case REF+9:
+ n = OP(scan) - REF;
+ s = regmystartp[n];
+ if (!s)
+ return(0);
+ if (!regmyendp[n])
+ return(0);
+ if (s == regmyendp[n])
+ break;
+ /* Inline the first character, for speed. */
+ if (*s != nextchar)
+ return(0);
+ ln = regmyendp[n] - s;
+ if (locinput + ln > regeol)
+ return 0;
+ if (ln > 1 && bcmp(s, locinput, ln) != 0)
+ return(0);
+ locinput += ln;
+ nextchar = *locinput;
+ break;
+
+ case NOTHING:
+ break;
+ case BACK:
+ break;
+ case OPEN+1:
+ case OPEN+2:
+ case OPEN+3:
+ case OPEN+4:
+ case OPEN+5:
+ case OPEN+6:
+ case OPEN+7:
+ case OPEN+8:
+ case OPEN+9:
+ n = OP(scan) - OPEN;
+ reginput = locinput;
+
+ regmystartp[n] = locinput; /* for REF */
+ if (regmatch(next)) {
+ /*
+ * Don't set startp if some later
+ * invocation of the same parentheses
+ * already has.
+ */
+ if (regstartp[n] == NULL)
+ regstartp[n] = locinput;
+ return(1);
+ } else
+ return(0);
+ /* NOTREACHED */
+ case CLOSE+1:
+ case CLOSE+2:
+ case CLOSE+3:
+ case CLOSE+4:
+ case CLOSE+5:
+ case CLOSE+6:
+ case CLOSE+7:
+ case CLOSE+8:
+ case CLOSE+9: {
+ n = OP(scan) - CLOSE;
+ reginput = locinput;
+
+ regmyendp[n] = locinput; /* for REF */
+ if (regmatch(next)) {
+ /*
+ * Don't set endp if some later
+ * invocation of the same parentheses
+ * already has.
+ */
+ if (regendp[n] == NULL) {
+ regendp[n] = locinput;
+ if (n > *reglastparen)
+ *reglastparen = n;
+ }
+ return(1);
+ } else
+ return(0);
+ }
+ /*NOTREACHED*/
+ case BRANCH: {
+ if (OP(next) != BRANCH) /* No choice. */
+ next = NEXTOPER(scan); /* Avoid recursion. */
+ else {
+ do {
+ reginput = locinput;
+ if (regmatch(NEXTOPER(scan)))
+ return(1);
+#ifdef REGALIGN
+ if (n = NEXT(scan))
+ scan += n;
+ else
+ scan = NULL;
+#else
+ scan = regnext(scan);
+#endif
+ } while (scan != NULL && OP(scan) == BRANCH);
+ return(0);
+ /* NOTREACHED */
+ }
+ }
+ break;
+ case STAR:
+ case PLUS:
+ /*
+ * Lookahead to avoid useless match attempts
+ * when we know what character comes next.
+ */
+ if (OP(next) == EXACTLY)
+ nextchar = *(OPERAND(next)+1);
+ else
+ nextchar = -1000;
+ ln = (OP(scan) == STAR) ? 0 : 1;
+ reginput = locinput;
+ n = regrepeat(NEXTOPER(scan));
+ while (n >= ln) {
+ /* If it could work, try it. */
+ if (nextchar == -1000 || *reginput == nextchar)
+ if (regmatch(next))
+ return(1);
+ /* Couldn't or didn't -- back up. */
+ n--;
+ reginput = locinput + n;
+ }
+ return(0);
+ case END:
+ reginput = locinput; /* put where regtry can find it */
+ return(1); /* Success! */
+ default:
+ printf("%x %d\n",scan,scan[1]);
+ FAIL("regexp memory corruption");
+ }
+
+ scan = next;
+ }
+
+ /*
+ * We get here only if there's trouble -- normally "case END" is
+ * the terminating point.
+ */
+ FAIL("corrupted regexp pointers");
+ /*NOTREACHED*/
+#ifdef lint
+ return 0;
+#endif
+}
+
+/*
+ - regrepeat - repeatedly match something simple, report how many
+ */
+/*
+ * [This routine now assumes that it will only match on things of length 1.
+ * That was true before, but now we assume scan - reginput is the count,
+ * rather than incrementing count on every character.]
+ */
+static int
+regrepeat(p)
+char *p;
+{
+ register char *scan;
+ register char *opnd;
+ register int c;
+ register char *loceol = regeol;
+
+ scan = reginput;
+ opnd = OPERAND(p);
+ switch (OP(p)) {
+ case ANY:
+ while (scan < loceol && *scan != '\n')
+ scan++;
+ break;
+ case EXACTLY: /* length of string is 1 */
+ opnd++;
+ while (scan < loceol && *opnd == *scan)
+ scan++;
+ break;
+ case ANYOF:
+ case ANYBUT:
+ c = UCHARAT(scan);
+ while (scan < loceol && !(opnd[c >> 3] & (1 << (c & 7)))) {
+ scan++;
+ c = UCHARAT(scan);
+ }
+ break;
+ case ALNUM:
+ while (isalpha(*scan) || isdigit(*scan) || *scan == '_')
+ scan++;
+ break;
+ case NALNUM:
+ while (scan < loceol && (!isalpha(*scan) && !isdigit(*scan) &&
+ *scan != '_'))
+ scan++;
+ break;
+ case SPACE:
+ while (scan < loceol && isspace(*scan))
+ scan++;
+ break;
+ case NSPACE:
+ while (scan < loceol && !isspace(*scan))
+ scan++;
+ break;
+ case DIGIT:
+ while (isdigit(*scan))
+ scan++;
+ break;
+ case NDIGIT:
+ while (scan < loceol && !isdigit(*scan))
+ scan++;
+ break;
+ default: /* Oh dear. Called inappropriately. */
+ FAIL("internal regexp foulup");
+ /* NOTREACHED */
+ }
+
+ c = scan - reginput;
+ reginput = scan;
+
+ return(c);
+}
+
+/*
+ - regnext - dig the "next" pointer out of a node
+ *
+ * [Note, when REGALIGN is defined there are two places in regmatch()
+ * that bypass this code for speed.]
+ */
+char *
+regnext(p)
+register char *p;
+{
+ register int offset;
+
+ if (p == &regdummy)
+ return(NULL);
+
+ offset = NEXT(p);
+ if (offset == 0)
+ return(NULL);
+
+#ifdef REGALIGN
+ return(p+offset);
+#else
+ if (OP(p) == BACK)
+ return(p-offset);
+ else
+ return(p+offset);
+#endif
+}
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