/* 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. */ /* $RCSfile: regexec.c,v $$Revision: 4.0.1.2 $$Date: 91/06/07 11:50:33 $ * * $Log: regexec.c,v $ * Revision 4.0.1.2 91/06/07 11:50:33 lwall * patch4: new copyright notice * patch4: // wouldn't use previous pattern if it started with a null character * * Revision 4.0.1.1 91/04/12 09:07:39 lwall * patch1: regexec only allocated space for 9 subexpresssions * * Revision 4.0 91/03/20 01:39:16 lwall * 4.0 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) 1991, Larry Wall **** **** You may distribute under the terms of either the GNU General Public **** License or the Artistic License, as specified in the README file. * * 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 #define isALNUM(c) (isascii(c) && (isalpha(c) || isdigit(c) || c == '_')) #define isSPACE(c) (isascii(c) && isspace(c)) #define isDIGIT(c) (isascii(c) && isdigit(c)) #define isUPPER(c) (isascii(c) && isupper(c)) /* * regexec and friends */ /* * Global work variables for regexec(). */ static char *regprecomp; static char *reginput; /* String-input pointer. */ static char regprev; /* char before regbol, \n if none */ 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 int regmyp_size = 0; static char **regmystartp = Null(char**); static char **regmyendp = Null(char**); /* * 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 */ /* Be paranoid... */ if (prog == NULL || string == NULL) { fatal("NULL regexp parameter"); return(0); } if (string == strbeg) /* is ^ valid at stringarg? */ regprev = '\n'; else { regprev = stringarg[-1]; if (!multiline && regprev == '\n') regprev = '\0'; /* force ^ to NOT match */ } 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 && (!(prog->reganch & ROPT_ANCH) || (multiline && prog->regback >= 0)) ) { if (stringarg == strbeg && 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 ^ . */ regbol = string; /* 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; /* Allocate our backreference arrays */ if ( regmyp_size < prog->nparens + 1 ) { /* Allocate or enlarge the arrays */ regmyp_size = prog->nparens + 1; if ( regmyp_size < 10 ) regmyp_size = 10; /* minimum */ if ( regmystartp ) { /* reallocate larger */ Renew(regmystartp,regmyp_size,char*); Renew(regmyendp, regmyp_size,char*); } else { /* Initial allocation */ New(1102,regmystartp,regmyp_size,char*); New(1102,regmyendp, regmyp_size,char*); } } /* Simplest case: anchored match need be tried only once. */ /* [unless multiline is set] */ if (prog->reganch & ROPT_ANCH) { 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--; while (s < strend) { if (*s++ == '\n') { if (s < strend && regtry(prog, s)) goto got_it; } } } goto phooey; } /* Messy cases: unanchored match. */ if (prog->regstart) { if (prog->reganch & ROPT_SKIP) { /* we have /x+whatever/ */ /* it must be a one character string */ i = prog->regstart->str_ptr[0]; while (s < strend) { if (*s == i) { if (regtry(prog, s)) goto got_it; s++; while (s < strend && *s == i) s++; } s++; } } else if (prog->regstart->str_pok == 3) { /* We know what string it must start with. */ #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) { int doevery = (prog->reganch & ROPT_SKIP) == 0; if (minlen) dontbother = minlen - 1; strend -= dontbother; /* don't bother with what can't match */ tmp = 1; /* We know what class it must start with. */ switch (OP(c)) { case ANYOF: c = OPERAND(c); while (s < strend) { i = UCHARAT(s); if (!(c[i >> 3] & (1 << (i&7)))) { if (tmp && regtry(prog, s)) goto got_it; else tmp = doevery; } else tmp = 1; s++; } break; case BOUND: if (minlen) dontbother++,strend--; if (s != string) { i = s[-1]; tmp = isALNUM(i); } else tmp = isALNUM(regprev); /* assume not alphanumeric */ while (s < strend) { i = *s; if (tmp != isALNUM(i)) { tmp = !tmp; if (regtry(prog, s)) goto got_it; } s++; } if ((minlen || tmp) && regtry(prog,s)) goto got_it; break; case NBOUND: if (minlen) dontbother++,strend--; if (s != string) { i = s[-1]; tmp = isALNUM(i); } else tmp = isALNUM(regprev); /* assume not alphanumeric */ while (s < strend) { i = *s; if (tmp != isALNUM(i)) tmp = !tmp; else if (regtry(prog, s)) goto got_it; s++; } if ((minlen || !tmp) && regtry(prog,s)) goto got_it; break; case ALNUM: while (s < strend) { i = *s; if (isALNUM(i)) { if (tmp && regtry(prog, s)) goto got_it; else tmp = doevery; } else tmp = 1; s++; } break; case NALNUM: while (s < strend) { i = *s; if (!isALNUM(i)) { if (tmp && regtry(prog, s)) goto got_it; else tmp = doevery; } else tmp = 1; s++; } break; case SPACE: while (s < strend) { if (isSPACE(*s)) { if (tmp && regtry(prog, s)) goto got_it; else tmp = doevery; } else tmp = 1; s++; } break; case NSPACE: while (s < strend) { if (!isSPACE(*s)) { if (tmp && regtry(prog, s)) goto got_it; else tmp = doevery; } else tmp = 1; s++; } break; case DIGIT: while (s < strend) { if (isDIGIT(*s)) { if (tmp && regtry(prog, s)) goto got_it; else tmp = doevery; } else tmp = 1; s++; } break; case NDIGIT: while (s < strend) { if (!isDIGIT(*s)) { if (tmp && regtry(prog, s)) goto got_it; else tmp = doevery; } else tmp = 1; s++; } break; } } else { if (minlen) dontbother = minlen - 1; 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->subbeg = prog->subbase = s; prog->subend = s+i; } 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 = prog->nparens; 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 ? regprev == '\n' : ((nextchar || locinput < regeol) && locinput[-1] == '\n') ) { /* regtill = regbol; */ break; } return(0); case EOL: if ((nextchar || locinput < regeol) && nextchar != '\n') return(0); if (!multiline && regeol - locinput > 1) return 0; /* regtill = regbol; */ 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 (regeol - locinput < ln) return 0; if (ln > 1 && bcmp(s, locinput, ln) != 0) return(0); locinput += ln; nextchar = *locinput; break; case ANYOF: s = OPERAND(scan); if (nextchar < 0) nextchar = UCHARAT(locinput); if (s[nextchar >> 3] & (1 << (nextchar&7))) return(0); if (!nextchar && locinput >= regeol) return 0; nextchar = *++locinput; break; case ALNUM: if (!nextchar) return(0); if (!isALNUM(nextchar)) return(0); nextchar = *++locinput; break; case NALNUM: if (!nextchar && locinput >= regeol) return(0); if (isALNUM(nextchar)) return(0); nextchar = *++locinput; break; case NBOUND: case BOUND: if (locinput == regbol) /* was last char in word? */ ln = isALNUM(regprev); else ln = isALNUM(locinput[-1]); n = isALNUM(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: n = ARG1(scan); /* which paren pair */ 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: n = ARG1(scan); /* which paren pair */ 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: { n = ARG1(scan); /* which paren pair */ 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 CURLY: ln = ARG1(scan); /* min to match */ n = ARG2(scan); /* max to match */ scan = NEXTOPER(scan) + 4; goto repeat; case STAR: ln = 0; n = 0; scan = NEXTOPER(scan); goto repeat; case PLUS: /* * Lookahead to avoid useless match attempts * when we know what character comes next. */ ln = 1; n = 0; scan = NEXTOPER(scan); repeat: if (OP(next) == EXACTLY) nextchar = *(OPERAND(next)+1); else nextchar = -1000; reginput = locinput; n = regrepeat(scan, n); if (!multiline && OP(next) == EOL && ln < n) ln = n; /* why back off? */ 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, max) char *p; int max; { register char *scan; register char *opnd; register int c; register char *loceol = regeol; scan = reginput; if (max && max < loceol - scan) loceol = scan + max; 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: c = UCHARAT(scan); while (scan < loceol && !(opnd[c >> 3] & (1 << (c & 7)))) { scan++; c = UCHARAT(scan); } break; case ALNUM: while (scan < loceol && isALNUM(*scan)) scan++; break; case NALNUM: while (scan < loceol && !isALNUM(*scan)) scan++; break; case SPACE: while (scan < loceol && isSPACE(*scan)) scan++; break; case NSPACE: while (scan < loceol && !isSPACE(*scan)) scan++; break; case DIGIT: while (scan < loceol && 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 == ®dummy) 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 }