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regexec.c
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regexec.c
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/* regexec.c
*/
/*
* "One Ring to rule them all, One Ring to find them..."
*/
/* 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.
*/
/*SUPPRESS 112*/
/*
* 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) 1991-1994, 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
static I32 regnarrate = 0;
static char* regprogram = 0;
#endif
/* Current curly descriptor */
typedef struct curcur CURCUR;
struct curcur {
int parenfloor; /* how far back to strip paren data */
int cur; /* how many instances of scan we've matched */
int min; /* the minimal number of scans to match */
int max; /* the maximal number of scans to match */
int minmod; /* whether to work our way up or down */
char * scan; /* the thing to match */
char * next; /* what has to match after it */
char * lastloc; /* where we started matching this scan */
CURCUR * oldcc; /* current curly before we started this one */
};
static CURCUR* regcc;
typedef I32 CHECKPOINT;
CHECKPOINT regcppush _((I32 parenfloor));
char * regcppop _((void));
CHECKPOINT
regcppush(parenfloor)
I32 parenfloor;
{
int retval = savestack_ix;
int i = (regsize - parenfloor) * 3;
int p;
SSCHECK(i + 5);
for (p = regsize; p > parenfloor; p--) {
SSPUSHPTR(regendp[p]);
SSPUSHPTR(regstartp[p]);
SSPUSHINT(p);
}
SSPUSHINT(regsize);
SSPUSHINT(*reglastparen);
SSPUSHPTR(reginput);
SSPUSHINT(i + 3);
SSPUSHINT(SAVEt_REGCONTEXT);
return retval;
}
char*
regcppop()
{
I32 i = SSPOPINT;
U32 paren = 0;
char *input;
char *tmps;
assert(i == SAVEt_REGCONTEXT);
i = SSPOPINT;
input = (char *) SSPOPPTR;
*reglastparen = SSPOPINT;
regsize = SSPOPINT;
for (i -= 3; i > 0; i -= 3) {
paren = (U32)SSPOPINT;
regstartp[paren] = (char *) SSPOPPTR;
tmps = (char*)SSPOPPTR;
if (paren <= *reglastparen)
regendp[paren] = tmps;
}
for (paren = *reglastparen + 1; paren <= regnpar; paren++) {
if (paren > regsize)
regstartp[paren] = Nullch;
regendp[paren] = Nullch;
}
return input;
}
#define regcpblow(cp) leave_scope(cp)
/*
* regexec and friends
*/
/*
* Forwards.
*/
static I32 regmatch _((char *prog));
static I32 regrepeat _((char *p, I32 max));
static I32 regtry _((regexp *prog, char *startpos));
/*
- regexec - match a regexp against a string
*/
I32
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 */
I32 minend; /* end of match must be at least minend after stringarg */
SV *screamer;
I32 safebase; /* no need to remember string in subbase */
{
register char *s;
register I32 i;
register char *c;
register char *startpos = stringarg;
register I32 tmp;
I32 minlen = 0; /* must match at least this many chars */
I32 dontbother = 0; /* how many characters not to try at end */
CURCUR cc;
cc.cur = 0;
regcc = &cc;
#ifdef DEBUGGING
regnarrate = debug & 512;
regprogram = prog->program;
#endif
/* Be paranoid... */
if (prog == NULL || startpos == NULL) {
croak("NULL regexp parameter");
return 0;
}
if (startpos == strbeg) /* is ^ valid at stringarg? */
regprev = '\n';
else {
regprev = stringarg[-1];
if (!multiline && regprev == '\n')
regprev = '\0'; /* force ^ to NOT match */
}
regprecomp = prog->precomp;
regnpar = prog->nparens;
/* Check validity of program. */
if (UCHARAT(prog->program) != MAGIC) {
FAIL("corrupted regexp program");
}
if (prog->do_folding) {
i = strend - startpos;
New(1101,c,i+1,char);
Copy(startpos, c, i+1, char);
startpos = c;
strend = startpos + i;
for (s = startpos; s < strend; s++)
if (isUPPER(*s))
*s = toLOWER(*s);
}
/* If there is a "must appear" string, look for it. */
s = startpos;
if (prog->regmust != Nullsv &&
(!(prog->reganch & ROPT_ANCH)
|| (multiline && prog->regback >= 0)) )
{
if (stringarg == strbeg && screamer) {
if (screamfirst[BmRARE(prog->regmust)] >= 0)
s = screaminstr(screamer,prog->regmust);
else
s = Nullch;
}
else
s = fbm_instr((unsigned char*)s, (unsigned char*)strend,
prog->regmust);
if (!s) {
++BmUSEFUL(prog->regmust); /* hooray */
goto phooey; /* not present */
}
else if (prog->regback >= 0) {
s -= prog->regback;
if (s < startpos)
s = startpos;
minlen = prog->regback + SvCUR(prog->regmust);
}
else if (!prog->naughty && --BmUSEFUL(prog->regmust) < 0) { /* boo */
SvREFCNT_dec(prog->regmust);
prog->regmust = Nullsv; /* disable regmust */
s = startpos;
}
else {
s = startpos;
minlen = SvCUR(prog->regmust);
}
}
/* Mark beginning of line for ^ . */
regbol = startpos;
/* Mark end of line for $ (and such) */
regeol = strend;
/* see how far we have to get to not match where we matched before */
regtill = startpos+minend;
/* Simplest case: anchored match need be tried only once. */
/* [unless multiline is set] */
if (prog->reganch & ROPT_ANCH) {
if (regtry(prog, startpos))
goto got_it;
else if (multiline || (prog->reganch & ROPT_IMPLICIT)) {
if (minlen)
dontbother = minlen - 1;
strend -= dontbother;
/* for multiline we only have to try after newlines */
if (s > startpos)
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 = SvPVX(prog->regstart)[0];
while (s < strend) {
if (*s == i) {
if (regtry(prog, s))
goto got_it;
s++;
while (s < strend && *s == i)
s++;
}
s++;
}
}
else if (SvPOK(prog->regstart) == 3) {
/* We know what string it must start with. */
while ((s = fbm_instr((unsigned char*)s,
(unsigned char*)strend, prog->regstart)) != NULL)
{
if (regtry(prog, s))
goto got_it;
s++;
}
}
else {
c = SvPVX(prog->regstart);
while ((s = ninstr(s, strend, c, c + SvCUR(prog->regstart))) != NULL)
{
if (regtry(prog, s))
goto got_it;
s++;
}
}
goto phooey;
}
/*SUPPRESS 560*/
if (c = prog->regstclass) {
I32 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 != startpos) {
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 != startpos) {
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:
prog->subbeg = strbeg;
prog->subend = strend;
if ((!safebase && (prog->nparens || sawampersand)) || prog->do_folding) {
strend += dontbother; /* uncheat */
i = strend - startpos + (stringarg - strbeg);
if (safebase) { /* no need for $digit later */
s = strbeg;
prog->subend = s+i;
}
else if (strbeg != prog->subbase) {
s = savepvn(strbeg,i); /* so $digit will work later */
if (prog->subbase)
Safefree(prog->subbase);
prog->subbeg = prog->subbase = s;
prog->subend = s+i;
}
else {
prog->subbeg = s = prog->subbase;
prog->subend = s+i;
}
s += (stringarg - strbeg);
for (i = 0; i <= prog->nparens; i++) {
if (prog->endp[i]) {
prog->startp[i] = s + (prog->startp[i] - startpos);
prog->endp[i] = s + (prog->endp[i] - startpos);
}
}
if (prog->do_folding)
Safefree(startpos);
}
return 1;
phooey:
if (prog->do_folding)
Safefree(startpos);
return 0;
}
/*
- regtry - try match at specific point
*/
static I32 /* 0 failure, 1 success */
regtry(prog, startpos)
regexp *prog;
char *startpos;
{
register I32 i;
register char **sp;
register char **ep;
reginput = startpos;
regstartp = prog->startp;
regendp = prog->endp;
reglastparen = &prog->lastparen;
prog->lastparen = 0;
regsize = 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] = startpos;
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 I32 /* 0 failure, 1 success */
regmatch(prog)
char *prog;
{
register char *scan; /* Current node. */
char *next; /* Next node. */
register I32 nextchar;
register I32 n; /* no or next */
register I32 ln; /* len or last */
register char *s; /* operand or save */
register char *locinput = reginput;
int minmod = 0;
nextchar = *locinput;
scan = prog;
while (scan != NULL) {
#ifdef DEBUGGING
if (regnarrate)
fprintf(stderr, "%2d%-8.8s\t<%.10s>\n",
scan - regprogram, regprop(scan), locinput);
#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 MBOL:
if (locinput == regbol
? regprev == '\n'
: ((nextchar || locinput < regeol) && locinput[-1] == '\n') )
{
break;
}
return 0;
case SBOL:
if (locinput == regbol && regprev == '\n')
break;
return 0;
case GBOL:
if (locinput == regbol)
break;
return 0;
case EOL:
if (multiline)
goto meol;
else
goto seol;
case MEOL:
meol:
if ((nextchar || locinput < regeol) && nextchar != '\n')
return 0;
break;
case SEOL:
seol:
if ((nextchar || locinput < regeol) && nextchar != '\n')
return 0;
if (regeol - locinput > 1)
return 0;
break;
case SANY:
if (!nextchar && locinput >= regeol)
return 0;
nextchar = *++locinput;
break;
case ANY:
if (!nextchar && 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 = regstartp[n];
if (!s)
return 0;
if (!regendp[n])
return 0;
if (s == regendp[n])
break;
/* Inline the first character, for speed. */
if (*s != nextchar)
return 0;
ln = regendp[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 */
regstartp[n] = locinput;
if (n > regsize)
regsize = n;
break;
case CLOSE:
n = ARG1(scan); /* which paren pair */
regendp[n] = locinput;
if (n > *reglastparen)
*reglastparen = n;
break;
case CURLYX: {
CURCUR cc;
CHECKPOINT cp = savestack_ix;
cc.oldcc = regcc;
regcc = &cc;
cc.parenfloor = *reglastparen;
cc.cur = -1;
cc.min = ARG1(scan);
cc.max = ARG2(scan);
cc.scan = NEXTOPER(scan) + 4;
cc.next = next;
cc.minmod = minmod;
cc.lastloc = 0;
reginput = locinput;
n = regmatch(PREVOPER(next)); /* start on the WHILEM */
regcpblow(cp);
regcc = cc.oldcc;
return n;
}
/* NOT REACHED */
case WHILEM: {
/*
* This is really hard to understand, because after we match
* what we're trying to match, we must make sure the rest of
* the RE is going to match for sure, and to do that we have
* to go back UP the parse tree by recursing ever deeper. And
* if it fails, we have to reset our parent's current state
* that we can try again after backing off.
*/
CURCUR* cc = regcc;
n = cc->cur + 1;
reginput = locinput;
/* If degenerate scan matches "", assume scan done. */
if (locinput == cc->lastloc) {
regcc = cc->oldcc;
ln = regcc->cur;
if (regmatch(cc->next))
return TRUE;
regcc->cur = ln;
regcc = cc;
return FALSE;
}
/* First just match a string of min scans. */
if (n < cc->min) {
cc->cur = n;
cc->lastloc = locinput;
return regmatch(cc->scan);
}
/* Prefer next over scan for minimal matching. */
if (cc->minmod) {
regcc = cc->oldcc;
ln = regcc->cur;
if (regmatch(cc->next))
return TRUE; /* All done. */
regcc->cur = ln;
regcc = cc;
if (n >= cc->max) /* Maximum greed exceeded? */
return FALSE;
/* Try scanning more and see if it helps. */
reginput = locinput;
cc->cur = n;
cc->lastloc = locinput;
return regmatch(cc->scan);
}
/* Prefer scan over next for maximal matching. */
if (n < cc->max) { /* More greed allowed? */
regcppush(cc->parenfloor);
cc->cur = n;
cc->lastloc = locinput;
if (regmatch(cc->scan))
return TRUE;
regcppop(); /* Restore some previous $<digit>s? */
reginput = locinput;
}
/* Failed deeper matches of scan, so see if this one works. */
regcc = cc->oldcc;
ln = regcc->cur;
if (regmatch(cc->next))
return TRUE;
regcc->cur = ln;
regcc = cc;
return FALSE;
}
/* NOT REACHED */
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
/*SUPPRESS 560*/
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 MINMOD:
minmod = 1;
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 = 32767;
scan = NEXTOPER(scan);
goto repeat;
case PLUS:
/*
* Lookahead to avoid useless match attempts
* when we know what character comes next.
*/
ln = 1;
n = 32767;
scan = NEXTOPER(scan);
repeat:
if (OP(next) == EXACTLY)
nextchar = *(OPERAND(next)+1);
else
nextchar = -1000;
reginput = locinput;
if (minmod) {
minmod = 0;
if (ln && regrepeat(scan, ln) < ln)
return 0;
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. */
if (regrepeat(scan, 1)) {
ln++;
reginput = locinput + ln;
}
else
return 0;
}
}
else {
n = regrepeat(scan, n);
if (ln < n && regkind[(U8)OP(next)] == EOL &&
(!multiline || OP(next) == SEOL))
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 SUCCEED:
case END:
reginput = locinput; /* put where regtry can find it */
return 1; /* Success! */
case IFMATCH:
reginput = locinput;
scan = NEXTOPER(scan);
if (!regmatch(scan))
return 0;
break;
case UNLESSM:
reginput = locinput;
scan = NEXTOPER(scan);
if (regmatch(scan))
return 0;
break;
default:
fprintf(stderr, "%x %d\n",(unsigned)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*/
return 0;
}
/*
- 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 I32
regrepeat(p, max)
char *p;
I32 max;
{
register char *scan;
register char *opnd;
register I32 c;
register char *loceol = regeol;
scan = reginput;
if (max != 32767 && max < loceol - scan)
loceol = scan + max;
opnd = OPERAND(p);
switch (OP(p)) {
case ANY:
while (scan < loceol && *scan != '\n')
scan++;
break;
case SANY:
scan = loceol;
break;
case EXACTLY: /* length of string is 1 */
opnd++;
while (scan < loceol && *opnd == *scan)
scan++;