forked from schacon/perl
/
regcomp.c
1396 lines (1315 loc) · 29.4 KB
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regcomp.c
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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: regcomp.c,v 4.0 91/03/20 01:39:01 lwall Locked $
*
* $Log: regcomp.c,v $
* Revision 4.0 91/03/20 01:39:01 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) 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 "INTERN.h"
#include "regcomp.h"
#ifdef MSDOS
# if defined(BUGGY_MSC6)
/* MSC 6.00A breaks on op/regexp.t test 85 unless we turn this off */
# pragma optimize("a",off)
/* But MSC 6.00A is happy with 'w', for aliases only across function calls*/
# pragma optimize("w",on )
# endif /* BUGGY_MSC6 */
#endif /* MSDOS */
#ifndef STATIC
#define STATIC static
#endif
#define ISMULT1(c) ((c) == '*' || (c) == '+' || (c) == '?')
#define ISMULT2(s) ((*s) == '*' || (*s) == '+' || (*s) == '?' || \
((*s) == '{' && regcurly(s)))
#define META "^$.[()|?+*\\"
/*
* Flags to be passed up and down.
*/
#define HASWIDTH 01 /* Known never to match null string. */
#define SIMPLE 02 /* Simple enough to be STAR/PLUS operand. */
#define SPSTART 04 /* Starts with * or +. */
#define WORST 0 /* Worst case. */
/*
* Global work variables for regcomp().
*/
static char *regprecomp; /* uncompiled string. */
static char *regparse; /* Input-scan pointer. */
static char *regxend; /* End of input for compile */
static int regnpar; /* () count. */
static char *regcode; /* Code-emit pointer; ®dummy = don't. */
static long regsize; /* Code size. */
static int regfold;
static int regsawbracket; /* Did we do {d,d} trick? */
/*
* Forward declarations for regcomp()'s friends.
*/
STATIC int regcurly();
STATIC char *reg();
STATIC char *regbranch();
STATIC char *regpiece();
STATIC char *regatom();
STATIC char *regclass();
STATIC char *regnode();
STATIC char *reganode();
STATIC void regc();
STATIC void reginsert();
STATIC void regtail();
STATIC void regoptail();
/*
- regcomp - compile a regular expression into internal code
*
* We can't allocate space until we know how big the compiled form will be,
* but we can't compile it (and thus know how big it is) until we've got a
* place to put the code. So we cheat: we compile it twice, once with code
* generation turned off and size counting turned on, and once "for real".
* This also means that we don't allocate space until we are sure that the
* thing really will compile successfully, and we never have to move the
* code and thus invalidate pointers into it. (Note that it has to be in
* one piece because free() must be able to free it all.) [NB: not true in perl]
*
* Beware that the optimization-preparation code in here knows about some
* of the structure of the compiled regexp. [I'll say.]
*/
regexp *
regcomp(exp,xend,fold)
char *exp;
char *xend;
int fold;
{
register regexp *r;
register char *scan;
register STR *longish;
STR *longest;
register int len;
register char *first;
int flags;
int backish;
int backest;
int curback;
extern char *safemalloc();
extern char *savestr();
int sawplus = 0;
if (exp == NULL)
fatal("NULL regexp argument");
/* First pass: determine size, legality. */
regfold = fold;
regparse = exp;
regxend = xend;
regprecomp = nsavestr(exp,xend-exp);
regsawbracket = 0;
regnpar = 1;
regsize = 0L;
regcode = ®dummy;
regc(MAGIC);
if (reg(0, &flags) == NULL) {
Safefree(regprecomp);
regprecomp = Nullch;
return(NULL);
}
/* Small enough for pointer-storage convention? */
if (regsize >= 32767L) /* Probably could be 65535L. */
FAIL("regexp too big");
/* Allocate space. */
Newc(1001, r, sizeof(regexp) + (unsigned)regsize, char, regexp);
if (r == NULL)
FAIL("regexp out of space");
/* Second pass: emit code. */
if (regsawbracket)
bcopy(regprecomp,exp,xend-exp);
r->precomp = regprecomp;
r->subbase = NULL;
regparse = exp;
regnpar = 1;
regcode = r->program;
regc(MAGIC);
if (reg(0, &flags) == NULL)
return(NULL);
/* Dig out information for optimizations. */
r->regstart = Nullstr; /* Worst-case defaults. */
r->reganch = 0;
r->regmust = Nullstr;
r->regback = -1;
r->regstclass = Nullch;
scan = r->program+1; /* First BRANCH. */
if (OP(regnext(scan)) == END) {/* Only one top-level choice. */
scan = NEXTOPER(scan);
first = scan;
while (OP(first) == OPEN ||
(OP(first) == BRANCH && OP(regnext(first)) != BRANCH) ||
(OP(first) == PLUS) ||
(OP(first) == CURLY && ARG1(first) > 0) ) {
if (OP(first) == PLUS)
sawplus = 2;
else
first += regarglen[OP(first)];
first = NEXTOPER(first);
}
/* Starting-point info. */
if (OP(first) == EXACTLY) {
r->regstart =
str_make(OPERAND(first)+1,*OPERAND(first));
if (r->regstart->str_cur > !(sawstudy|fold))
fbmcompile(r->regstart,fold);
}
else if ((exp = index(simple,OP(first))) && exp > simple)
r->regstclass = first;
else if (OP(first) == BOUND || OP(first) == NBOUND)
r->regstclass = first;
else if (OP(first) == BOL ||
(OP(first) == STAR && OP(NEXTOPER(first)) == ANY) )
r->reganch = 1; /* kinda turn .* into ^.* */
r->reganch |= sawplus;
#ifdef DEBUGGING
if (debug & 512)
fprintf(stderr,"first %d next %d offset %d\n",
OP(first), OP(NEXTOPER(first)), first - scan);
#endif
/*
* If there's something expensive in the r.e., find the
* longest literal string that must appear and make it the
* regmust. Resolve ties in favor of later strings, since
* the regstart check works with the beginning of the r.e.
* and avoiding duplication strengthens checking. Not a
* strong reason, but sufficient in the absence of others.
* [Now we resolve ties in favor of the earlier string if
* it happens that curback has been invalidated, since the
* earlier string may buy us something the later one won't.]
*/
longish = str_make("",0);
longest = str_make("",0);
len = 0;
curback = 0;
backish = 0;
backest = 0;
while (OP(scan) != END) {
if (OP(scan) == BRANCH) {
if (OP(regnext(scan)) == BRANCH) {
curback = -30000;
while (OP(scan) == BRANCH)
scan = regnext(scan);
}
else /* single branch is ok */
scan = NEXTOPER(scan);
}
if (OP(scan) == EXACTLY) {
char *t;
first = scan;
while (OP(t = regnext(scan)) == CLOSE)
scan = t;
if (curback - backish == len) {
str_ncat(longish, OPERAND(first)+1,
*OPERAND(first));
len += *OPERAND(first);
curback += *OPERAND(first);
first = regnext(scan);
}
else if (*OPERAND(first) >= len + (curback >= 0)) {
len = *OPERAND(first);
str_nset(longish, OPERAND(first)+1,len);
backish = curback;
curback += len;
first = regnext(scan);
}
else
curback += *OPERAND(first);
}
else if (index(varies,OP(scan))) {
curback = -30000;
len = 0;
if (longish->str_cur > longest->str_cur) {
str_sset(longest,longish);
backest = backish;
}
str_nset(longish,"",0);
}
else if (index(simple,OP(scan))) {
curback++;
len = 0;
if (longish->str_cur > longest->str_cur) {
str_sset(longest,longish);
backest = backish;
}
str_nset(longish,"",0);
}
scan = regnext(scan);
}
/* Prefer earlier on tie, unless we can tail match latter */
if (longish->str_cur + (OP(first) == EOL) > longest->str_cur) {
str_sset(longest,longish);
backest = backish;
}
else
str_nset(longish,"",0);
if (longest->str_cur
&&
(!r->regstart
||
!fbminstr(r->regstart->str_ptr,
r->regstart->str_ptr + r->regstart->str_cur,
longest)
)
)
{
r->regmust = longest;
if (backest < 0)
backest = -1;
r->regback = backest;
if (longest->str_cur
> !(sawstudy || fold || OP(first) == EOL) )
fbmcompile(r->regmust,fold);
r->regmust->str_u.str_useful = 100;
if (OP(first) == EOL && longish->str_cur)
r->regmust->str_pok |= SP_TAIL;
}
else {
str_free(longest);
longest = Nullstr;
}
str_free(longish);
}
r->do_folding = fold;
r->nparens = regnpar - 1;
New(1002, r->startp, regnpar, char*);
New(1002, r->endp, regnpar, char*);
#ifdef DEBUGGING
if (debug & 512)
regdump(r);
#endif
return(r);
}
/*
- reg - regular expression, i.e. main body or parenthesized thing
*
* Caller must absorb opening parenthesis.
*
* Combining parenthesis handling with the base level of regular expression
* is a trifle forced, but the need to tie the tails of the branches to what
* follows makes it hard to avoid.
*/
static char *
reg(paren, flagp)
int paren; /* Parenthesized? */
int *flagp;
{
register char *ret;
register char *br;
register char *ender;
register int parno;
int flags;
*flagp = HASWIDTH; /* Tentatively. */
/* Make an OPEN node, if parenthesized. */
if (paren) {
parno = regnpar;
regnpar++;
ret = reganode(OPEN, parno);
} else
ret = NULL;
/* Pick up the branches, linking them together. */
br = regbranch(&flags);
if (br == NULL)
return(NULL);
if (ret != NULL)
regtail(ret, br); /* OPEN -> first. */
else
ret = br;
if (!(flags&HASWIDTH))
*flagp &= ~HASWIDTH;
*flagp |= flags&SPSTART;
while (*regparse == '|') {
regparse++;
br = regbranch(&flags);
if (br == NULL)
return(NULL);
regtail(ret, br); /* BRANCH -> BRANCH. */
if (!(flags&HASWIDTH))
*flagp &= ~HASWIDTH;
*flagp |= flags&SPSTART;
}
/* Make a closing node, and hook it on the end. */
if (paren)
ender = reganode(CLOSE, parno);
else
ender = regnode(END);
regtail(ret, ender);
/* Hook the tails of the branches to the closing node. */
for (br = ret; br != NULL; br = regnext(br))
regoptail(br, ender);
/* Check for proper termination. */
if (paren && *regparse++ != ')') {
FAIL("unmatched () in regexp");
} else if (!paren && regparse < regxend) {
if (*regparse == ')') {
FAIL("unmatched () in regexp");
} else
FAIL("junk on end of regexp"); /* "Can't happen". */
/* NOTREACHED */
}
return(ret);
}
/*
- regbranch - one alternative of an | operator
*
* Implements the concatenation operator.
*/
static char *
regbranch(flagp)
int *flagp;
{
register char *ret;
register char *chain;
register char *latest;
int flags;
*flagp = WORST; /* Tentatively. */
ret = regnode(BRANCH);
chain = NULL;
while (regparse < regxend && *regparse != '|' && *regparse != ')') {
latest = regpiece(&flags);
if (latest == NULL)
return(NULL);
*flagp |= flags&HASWIDTH;
if (chain == NULL) /* First piece. */
*flagp |= flags&SPSTART;
else
regtail(chain, latest);
chain = latest;
}
if (chain == NULL) /* Loop ran zero times. */
(void) regnode(NOTHING);
return(ret);
}
/*
- regpiece - something followed by possible [*+?]
*
* Note that the branching code sequences used for ? and the general cases
* of * and + are somewhat optimized: they use the same NOTHING node as
* both the endmarker for their branch list and the body of the last branch.
* It might seem that this node could be dispensed with entirely, but the
* endmarker role is not redundant.
*/
static char *
regpiece(flagp)
int *flagp;
{
register char *ret;
register char op;
register char *next;
int flags;
char *origparse = regparse;
int orignpar = regnpar;
char *max;
int iter;
char ch;
ret = regatom(&flags);
if (ret == NULL)
return(NULL);
op = *regparse;
/* Here's a total kludge: if after the atom there's a {\d+,?\d*}
* then we decrement the first number by one and reset our
* parsing back to the beginning of the same atom. If the first number
* is down to 0, decrement the second number instead and fake up
* a ? after it. Given the way this compiler doesn't keep track
* of offsets on the first pass, this is the only way to replicate
* a piece of code. Sigh.
*/
if (op == '{' && regcurly(regparse)) {
next = regparse + 1;
max = Nullch;
while (isdigit(*next) || *next == ',') {
if (*next == ',') {
if (max)
break;
else
max = next;
}
next++;
}
if (*next == '}') { /* got one */
if (!max)
max = next;
regparse++;
iter = atoi(regparse);
if (flags&SIMPLE) { /* we can do it right after all */
int tmp;
reginsert(CURLY, ret);
if (iter > 0)
*flagp = (WORST|HASWIDTH);
if (*max == ',')
max++;
else
max = regparse;
tmp = atoi(max);
if (tmp && tmp < iter)
fatal("Can't do {n,m} with n > m");
if (regcode != ®dummy) {
#ifdef REGALIGN
*(unsigned short *)(ret+3) = iter;
*(unsigned short *)(ret+5) = tmp;
#else
ret[3] = iter >> 8; ret[4] = iter & 0377;
ret[5] = tmp >> 8; ret[6] = tmp & 0377;
#endif
}
regparse = next;
goto nest_check;
}
regsawbracket++; /* remember we clobbered exp */
if (iter > 0) {
ch = *max;
sprintf(regparse,"%.*d", max-regparse, iter - 1);
*max = ch;
if (*max == ',' && max[1] != '}') {
if (atoi(max+1) <= 0)
fatal("Can't do {n,m} with n > m");
ch = *next;
sprintf(max+1,"%.*d", next-(max+1), atoi(max+1) - 1);
*next = ch;
}
if (iter != 1 || *max == ',') {
regparse = origparse; /* back up input pointer */
regnpar = orignpar; /* don't make more parens */
}
else {
regparse = next;
goto nest_check;
}
*flagp = flags;
return ret;
}
if (*max == ',') {
max++;
iter = atoi(max);
if (max == next) { /* any number more? */
regparse = next;
op = '*'; /* fake up one with a star */
}
else if (iter > 0) {
op = '?'; /* fake up optional atom */
ch = *next;
sprintf(max,"%.*d", next-max, iter - 1);
*next = ch;
if (iter == 1)
regparse = next;
else {
regparse = origparse - 1; /* offset ++ below */
regnpar = orignpar;
}
}
else
fatal("Can't do {n,0}");
}
else
fatal("Can't do {0}");
}
}
if (!ISMULT1(op)) {
*flagp = flags;
return(ret);
}
if (!(flags&HASWIDTH) && op != '?')
FAIL("regexp *+ operand could be empty");
*flagp = (op != '+') ? (WORST|SPSTART) : (WORST|HASWIDTH);
if (op == '*' && (flags&SIMPLE))
reginsert(STAR, ret);
else if (op == '*') {
/* Emit x* as (x&|), where & means "self". */
reginsert(BRANCH, ret); /* Either x */
regoptail(ret, regnode(BACK)); /* and loop */
regoptail(ret, ret); /* back */
regtail(ret, regnode(BRANCH)); /* or */
regtail(ret, regnode(NOTHING)); /* null. */
} else if (op == '+' && (flags&SIMPLE))
reginsert(PLUS, ret);
else if (op == '+') {
/* Emit x+ as x(&|), where & means "self". */
next = regnode(BRANCH); /* Either */
regtail(ret, next);
regtail(regnode(BACK), ret); /* loop back */
regtail(next, regnode(BRANCH)); /* or */
regtail(ret, regnode(NOTHING)); /* null. */
} else if (op == '?') {
/* Emit x? as (x|) */
reginsert(BRANCH, ret); /* Either x */
regtail(ret, regnode(BRANCH)); /* or */
next = regnode(NOTHING); /* null. */
regtail(ret, next);
regoptail(ret, next);
}
nest_check:
regparse++;
if (ISMULT2(regparse))
FAIL("nested *?+ in regexp");
return(ret);
}
/*
- regatom - the lowest level
*
* Optimization: gobbles an entire sequence of ordinary characters so that
* it can turn them into a single node, which is smaller to store and
* faster to run. Backslashed characters are exceptions, each becoming a
* separate node; the code is simpler that way and it's not worth fixing.
*
* [Yes, it is worth fixing, some scripts can run twice the speed.]
*/
static char *
regatom(flagp)
int *flagp;
{
register char *ret;
int flags;
*flagp = WORST; /* Tentatively. */
switch (*regparse++) {
case '^':
ret = regnode(BOL);
break;
case '$':
ret = regnode(EOL);
break;
case '.':
ret = regnode(ANY);
*flagp |= HASWIDTH|SIMPLE;
break;
case '[':
ret = regclass();
*flagp |= HASWIDTH|SIMPLE;
break;
case '(':
ret = reg(1, &flags);
if (ret == NULL)
return(NULL);
*flagp |= flags&(HASWIDTH|SPSTART);
break;
case '|':
case ')':
FAIL("internal urp in regexp"); /* Supposed to be caught earlier. */
break;
case '?':
case '+':
case '*':
FAIL("?+* follows nothing in regexp");
break;
case '\\':
switch (*regparse) {
case 'w':
ret = regnode(ALNUM);
*flagp |= HASWIDTH|SIMPLE;
regparse++;
break;
case 'W':
ret = regnode(NALNUM);
*flagp |= HASWIDTH|SIMPLE;
regparse++;
break;
case 'b':
ret = regnode(BOUND);
*flagp |= SIMPLE;
regparse++;
break;
case 'B':
ret = regnode(NBOUND);
*flagp |= SIMPLE;
regparse++;
break;
case 's':
ret = regnode(SPACE);
*flagp |= HASWIDTH|SIMPLE;
regparse++;
break;
case 'S':
ret = regnode(NSPACE);
*flagp |= HASWIDTH|SIMPLE;
regparse++;
break;
case 'd':
ret = regnode(DIGIT);
*flagp |= HASWIDTH|SIMPLE;
regparse++;
break;
case 'D':
ret = regnode(NDIGIT);
*flagp |= HASWIDTH|SIMPLE;
regparse++;
break;
case 'n':
case 'r':
case 't':
case 'f':
case 'e':
case 'a':
case 'x':
case 'c':
case '0':
goto defchar;
case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
{
int num = atoi(regparse);
if (num > 9 && num >= regnpar)
goto defchar;
else {
ret = reganode(REF, num);
while (isascii(*regparse) && isdigit(*regparse))
regparse++;
*flagp |= SIMPLE;
}
}
break;
case '\0':
if (regparse >= regxend)
FAIL("trailing \\ in regexp");
/* FALL THROUGH */
default:
goto defchar;
}
break;
default: {
register int len;
register char ender;
register char *p;
char *oldp;
int numlen;
defchar:
ret = regnode(EXACTLY);
regc(0); /* save spot for len */
for (len=0, p=regparse-1;
len < 127 && p < regxend;
len++)
{
oldp = p;
switch (*p) {
case '^':
case '$':
case '.':
case '[':
case '(':
case ')':
case '|':
goto loopdone;
case '\\':
switch (*++p) {
case 'w':
case 'W':
case 'b':
case 'B':
case 's':
case 'S':
case 'd':
case 'D':
--p;
goto loopdone;
case 'n':
ender = '\n';
p++;
break;
case 'r':
ender = '\r';
p++;
break;
case 't':
ender = '\t';
p++;
break;
case 'f':
ender = '\f';
p++;
break;
case 'e':
ender = '\033';
p++;
break;
case 'a':
ender = '\007';
p++;
break;
case 'x':
ender = scanhex(++p, 2, &numlen);
p += numlen;
break;
case 'c':
p++;
ender = *p++;
if (islower(ender))
ender = toupper(ender);
ender ^= 64;
break;
case '0': case '1': case '2': case '3':case '4':
case '5': case '6': case '7': case '8':case '9':
if (*p == '0' ||
(isdigit(p[1]) && atoi(p) >= regnpar) ) {
ender = scanoct(p, 3, &numlen);
p += numlen;
}
else {
--p;
goto loopdone;
}
break;
case '\0':
if (p >= regxend)
FAIL("trailing \\ in regexp");
/* FALL THROUGH */
default:
ender = *p++;
break;
}
break;
default:
ender = *p++;
break;
}
if (regfold && isupper(ender))
ender = tolower(ender);
if (ISMULT2(p)) { /* Back off on ?+*. */
if (len)
p = oldp;
else {
len++;
regc(ender);
}
break;
}
regc(ender);
}
loopdone:
regparse = p;
if (len <= 0)
FAIL("internal disaster in regexp");
*flagp |= HASWIDTH;
if (len == 1)
*flagp |= SIMPLE;
if (regcode != ®dummy)
*OPERAND(ret) = len;
regc('\0');
}
break;
}
return(ret);
}
static void
regset(bits,def,c)
char *bits;
int def;
register int c;
{
if (regcode == ®dummy)
return;
c &= 255;
if (def)
bits[c >> 3] &= ~(1 << (c & 7));
else
bits[c >> 3] |= (1 << (c & 7));
}
static char *
regclass()
{
register char *bits;
register int class;
register int lastclass;
register int range = 0;
register char *ret;
register int def;
int numlen;
ret = regnode(ANYOF);
if (*regparse == '^') { /* Complement of range. */
regparse++;
def = 0;
} else {
def = 255;
}
bits = regcode;
for (class = 0; class < 32; class++)
regc(def);
if (*regparse == ']' || *regparse == '-')
goto skipcond; /* allow 1st char to be ] or - */
while (regparse < regxend && *regparse != ']') {
skipcond:
class = UCHARAT(regparse++);
if (class == '\\') {
class = UCHARAT(regparse++);
switch (class) {
case 'w':
for (class = 'a'; class <= 'z'; class++)
regset(bits,def,class);
for (class = 'A'; class <= 'Z'; class++)
regset(bits,def,class);
for (class = '0'; class <= '9'; class++)
regset(bits,def,class);
regset(bits,def,'_');
lastclass = 1234;
continue;
case 's':
regset(bits,def,' ');
regset(bits,def,'\t');
regset(bits,def,'\r');
regset(bits,def,'\f');
regset(bits,def,'\n');
lastclass = 1234;
continue;
case 'd':
for (class = '0'; class <= '9'; class++)
regset(bits,def,class);
lastclass = 1234;
continue;
case 'n':
class = '\n';
break;
case 'r':
class = '\r';
break;
case 't':
class = '\t';
break;
case 'f':
class = '\f';
break;
case 'b':
class = '\b';
break;
case 'e':
class = '\033';
break;
case 'a':
class = '\007';
break;
case 'x':
class = scanhex(regparse, 2, &numlen);
regparse += numlen;
break;
case 'c':
class = *regparse++;
if (islower(class))
class = toupper(class);
class ^= 64;
break;
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
class = scanoct(--regparse, 3, &numlen);
regparse += numlen;
break;
}
}
if (range) {
if (lastclass > class)
FAIL("invalid [] range in regexp");
range = 0;
}
else {
lastclass = class;
if (*regparse == '-' && regparse+1 < regxend &&
regparse[1] != ']') {
regparse++;
range = 1;
continue; /* do it next time */
}
}
for ( ; lastclass <= class; lastclass++) {
regset(bits,def,lastclass);
if (regfold && isupper(lastclass))