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openldap/contrib/tweb/regular.c
Kurt Spanier 884d6832d5 Initial revision
1999-09-10 17:33:39 +00:00

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/*_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
* *
* regular.c.. *
* *
* Function:..Routine for TWEB -> regular expressions *
* *
* *
* *
* Authors:...Dr. Kurt Spanier & Bernhard Winkler, *
* Zentrum fuer Datenverarbeitung, Bereich Entwicklung *
* neuer Dienste, Universitaet Tuebingen, GERMANY *
* *
* ZZZZZ DDD V V *
* Creation date: Z D D V V *
* January 20 1998 Z D D V V *
* Last modification: Z D D V V *
* December 31 1998 ZZZZZ DDD V *
* *
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_*/
/*
* $Id: regular.c,v 1.6 1999/09/10 15:01:19 zrnsk01 Exp $
*
*/
#include "tgeneral.h"
#include "tglobal.h"
#include "regular_exp.h"
#include "regular.h"
#include "support_exp.h"
PUBLIC void tweb_regerror(s)
char *s;
{
#ifdef ERRAVAIL
error("regexp: %s", s);
#else
/* fprintf(stderr, "regexp(3): %s", s);
exit(1);
*/
/* TWEB: error-logging by syslog */
if (dosyslog) syslog (LOG_INFO,
"ALLOW/DENY/GRANT/REFUSE - regexp-error: %s", s);
exit_tweb( 1 );
#endif
/* NOTREACHED */
}
/*
* tweb_regsub
*
* 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.
*/
#ifndef CHARBITS
#define UCHARAT(p) ((int)*(unsigned char *)(p))
#else
#define UCHARAT(p) ((int)*(p)&CHARBITS)
#endif
/*
- tweb_regsub - perform substitutions after a regexp match
*/
PUBLIC void tweb_regsub(prog, source, dest)
regexp *prog;
char *source;
char *dest;
{
register char *src;
register char *dst;
register char c;
register int no;
register int len;
extern char *strncpy();
if (prog == NULL || source == NULL || dest == NULL) {
tweb_regerror("NULL parm to tweb_regsub");
return;
}
if (UCHARAT(prog->program) != MAGIC) {
tweb_regerror("damaged regexp fed to tweb_regsub");
return;
}
src = source;
dst = dest;
while ((c = *src++) != '\0') {
if (c == '&')
no = 0;
else if (c == '\\' && '0' <= *src && *src <= '9')
no = *src++ - '0';
else
no = -1;
if (no < 0) { /* Ordinary character. */
if (c == '\\' && (*src == '\\' || *src == '&'))
c = *src++;
*dst++ = c;
} else if (prog->startp[no] != NULL && prog->endp[no] != NULL) {
len = prog->endp[no] - prog->startp[no];
(void) strncpy(dst, prog->startp[no], len);
dst += len;
if (len != 0 && *(dst-1) == '\0') { /* strncpy hit NUL. */
tweb_regerror("damaged match string");
return;
}
}
}
*dst++ = '\0';
}
/*
* tweb_regcomp and tweb_regexec -- tweb_regsub and tweb_regerror are elsewhere
*
* 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.
*
* 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.
*/
/*
* The "internal use only" fields in regexp.h are present to pass info from
* compile to execute that permits the execute phase to run lots faster on
* simple cases. They are:
*
* regstart char that must begin a match; '\0' if none obvious
* reganch is the match anchored (at beginning-of-line only)?
* regmust string (pointer into program) that match must include, or NULL
* regmlen length of regmust string
*
* Regstart and reganch permit very fast decisions on suitable starting points
* for a match, cutting down the work a lot. Regmust permits fast rejection
* of lines that cannot possibly match. The regmust tests are costly enough
* that tweb_regcomp() supplies a regmust only if the r.e. contains something
* potentially expensive (at present, the only such thing detected is * or +
* at the start of the r.e., which can involve a lot of backup). Regmlen is
* supplied because the test in tweb_regexec() needs it and tweb_regcomp() is computing
* it anyway.
*/
/*
* Structure for regexp "program". This is essentially a linear encoding
* of a nondeterministic finite-state machine (aka syntax charts or
* "railroad normal form" in parsing technology). Each node is an opcode
* plus a "next" pointer, possibly plus an operand. "Next" pointers of
* all nodes except BRANCH implement concatenation; a "next" pointer with
* a BRANCH on both ends of it is connecting two alternatives. (Here we
* have one of the subtle syntax dependencies: an individual BRANCH (as
* opposed to a collection of them) is never concatenated with anything
* because of operator precedence.) The operand of some types of node is
* a literal string; for others, it is a node leading into a sub-FSM. In
* particular, the operand of a BRANCH node is the first node of the branch.
* (NB this is *not* a tree structure: the tail of the branch connects
* to the thing following the set of BRANCHes.) The opcodes are:
*/
/*#include "regular.h"*/
/*
- tweb_regcomp - compile a regular expression into internal code
e*
* 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.)
*
* Beware that the optimization-preparation code in here knows about some
* of the structure of the compiled regexp.
*/
PUBLIC regexp * tweb_regcomp(exp)
char *exp;
{
register regexp *r;
register char *scan;
register char *longest;
register int len;
int flags;
if (exp == NULL)
FAIL("NULL argument");
/* First pass: determine size, legality. */
regparse = exp;
regnpar = 1;
regsize = 0L;
regcode = &regdummy;
tweb_regc(MAGIC);
if (tweb_reg(0, &flags) == NULL)
return(NULL);
/* Small enough for pointer-storage convention? */
if (regsize >= 32767L) /* Probably could be 65535L. */
FAIL("regexp too big");
/* Allocate space. */
r = (regexp *)malloc(sizeof(regexp) + (unsigned)regsize);
if (r == NULL)
FAIL("out of space");
/* Second pass: emit code. */
regparse = exp;
regnpar = 1;
regcode = r->program;
tweb_regc(MAGIC);
if (tweb_reg(0, &flags) == NULL)
return(NULL);
/* Dig out information for optimizations. */
r->regstart = '\0'; /* Worst-case defaults. */
r->reganch = 0;
r->regmust = NULL;
r->regmlen = 0;
scan = r->program+1; /* First BRANCH. */
if (OP(tweb_regnext(scan)) == END) { /* Only one top-level choice. */
scan = OPERAND(scan);
/* Starting-point info. */
if (OP(scan) == EXACTLY)
r->regstart = *OPERAND(scan);
else if (OP(scan) == BOL)
r->reganch++;
/*
* 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.
*/
if (flags&SPSTART) {
longest = NULL;
len = 0;
for (; scan != NULL; scan = tweb_regnext(scan))
if (OP(scan) == EXACTLY && strlen(OPERAND(scan)) >= len) {
longest = OPERAND(scan);
len = strlen(OPERAND(scan));
}
r->regmust = longest;
r->regmlen = len;
}
}
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.
*/
PRIVATE char * tweb_reg(paren, flagp)
int paren; /* Parenthesized? */
int *flagp;
{
register char *ret;
register char *br;
register char *ender;
register int parno = 0;
int flags;
*flagp = HASWIDTH; /* Tentatively. */
/* Make an OPEN node, if parenthesized. */
if (paren) {
if (regnpar >= NSUBEXP)
FAIL("too many ()");
parno = regnpar;
regnpar++;
ret = tweb_regnode(OPEN+parno);
} else
ret = NULL;
/* Pick up the branches, linking them together. */
br = tweb_regbranch(&flags);
if (br == NULL)
return(NULL);
if (ret != NULL)
tweb_regtail(ret, br); /* OPEN -> first. */
else
ret = br;
if (!(flags&HASWIDTH))
*flagp &= ~HASWIDTH;
*flagp |= flags&SPSTART;
while (*regparse == '|') {
regparse++;
br = tweb_regbranch(&flags);
if (br == NULL)
return(NULL);
tweb_regtail(ret, br); /* BRANCH -> BRANCH. */
if (!(flags&HASWIDTH))
*flagp &= ~HASWIDTH;
*flagp |= flags&SPSTART;
}
/* Make a closing node, and hook it on the end. */
ender = tweb_regnode((paren) ? CLOSE+parno : END);
tweb_regtail(ret, ender);
/* Hook the tails of the branches to the closing node. */
for (br = ret; br != NULL; br = tweb_regnext(br))
tweb_regoptail(br, ender);
/* Check for proper termination. */
if (paren && *regparse++ != ')') {
FAIL("unmatched ()");
} else if (!paren && *regparse != '\0') {
if (*regparse == ')') {
FAIL("unmatched ()");
} else
FAIL("junk on end"); /* "Can't happen". */
/* NOTREACHED */
}
return(ret);
}
/*
- tweb_regbranch - one alternative of an | operator
*
* Implements the concatenation operator.
*/
PRIVATE char * tweb_regbranch(flagp)
int *flagp;
{
register char *ret;
register char *chain;
register char *latest;
int flags;
*flagp = WORST; /* Tentatively. */
ret = tweb_regnode(BRANCH);
chain = NULL;
while (*regparse != '\0' && *regparse != '|' && *regparse != ')') {
latest = tweb_regpiece(&flags);
if (latest == NULL)
return(NULL);
*flagp |= flags&HASWIDTH;
if (chain == NULL) /* First piece. */
*flagp |= flags&SPSTART;
else
tweb_regtail(chain, latest);
chain = latest;
}
if (chain == NULL) /* Loop ran zero times. */
(void) tweb_regnode(NOTHING);
return(ret);
}
/*
- tweb_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.
*/
PRIVATE char * tweb_regpiece(flagp)
int *flagp;
{
register char *ret;
register char op;
register char *next;
int flags;
ret = tweb_regatom(&flags);
if (ret == NULL)
return(NULL);
op = *regparse;
if (!ISMULT(op)) {
*flagp = flags;
return(ret);
}
if (!(flags&HASWIDTH) && op != '?')
FAIL("*+ operand could be empty");
*flagp = (op != '+') ? (WORST|SPSTART) : (WORST|HASWIDTH);
if (op == '*' && (flags&SIMPLE))
tweb_reginsert(STAR, ret);
else if (op == '*') {
/* Emit x* as (x&|), where & means "self". */
tweb_reginsert(BRANCH, ret); /* Either x */
tweb_regoptail(ret, tweb_regnode(BACK)); /* and loop */
tweb_regoptail(ret, ret); /* back */
tweb_regtail(ret, tweb_regnode(BRANCH)); /* or */
tweb_regtail(ret, tweb_regnode(NOTHING)); /* null. */
} else if (op == '+' && (flags&SIMPLE))
tweb_reginsert(PLUS, ret);
else if (op == '+') {
/* Emit x+ as x(&|), where & means "self". */
next = tweb_regnode(BRANCH); /* Either */
tweb_regtail(ret, next);
tweb_regtail(tweb_regnode(BACK), ret); /* loop back */
tweb_regtail(next, tweb_regnode(BRANCH)); /* or */
tweb_regtail(ret, tweb_regnode(NOTHING)); /* null. */
} else if (op == '?') {
/* Emit x? as (x|) */
tweb_reginsert(BRANCH, ret); /* Either x */
tweb_regtail(ret, tweb_regnode(BRANCH)); /* or */
next = tweb_regnode(NOTHING); /* null. */
tweb_regtail(ret, next);
tweb_regoptail(ret, next);
}
regparse++;
if (ISMULT(*regparse))
FAIL("nested *?+");
return(ret);
}
/*
- tweb_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.
*/
PRIVATE char * tweb_regatom(flagp)
int *flagp;
{
register char *ret;
int flags;
*flagp = WORST; /* Tentatively. */
switch (*regparse++) {
case '^':
ret = tweb_regnode(BOL);
break;
case '$':
ret = tweb_regnode(EOL);
break;
case '.':
ret = tweb_regnode(ANY);
*flagp |= HASWIDTH|SIMPLE;
break;
case '[': {
register int class;
register int classend;
if (*regparse == '^') { /* Complement of range. */
ret = tweb_regnode(ANYBUT);
regparse++;
} else
ret = tweb_regnode(ANYOF);
if (*regparse == ']' || *regparse == '-')
tweb_regc(*regparse++);
while (*regparse != '\0' && *regparse != ']') {
if (*regparse == '-') {
regparse++;
if (*regparse == ']' || *regparse == '\0')
tweb_regc('-');
else {
class = UCHARAT(regparse-2)+1;
classend = UCHARAT(regparse);
if (class > classend+1)
FAIL("invalid [] range");
for (; class <= classend; class++)
tweb_regc(class);
regparse++;
}
} else
tweb_regc(*regparse++);
}
tweb_regc('\0');
if (*regparse != ']')
FAIL("unmatched []");
regparse++;
*flagp |= HASWIDTH|SIMPLE;
}
break;
case '(':
ret = tweb_reg(1, &flags);
if (ret == NULL)
return(NULL);
*flagp |= flags&(HASWIDTH|SPSTART);
break;
case '\0':
case '|':
case ')':
FAIL("internal urp"); /* Supposed to be caught earlier. */
break;
case '?':
case '+':
case '*':
FAIL("?+* follows nothing");
break;
case '\\':
if (*regparse == '\0')
FAIL("trailing \\");
ret = tweb_regnode(EXACTLY);
tweb_regc(*regparse++);
tweb_regc('\0');
*flagp |= HASWIDTH|SIMPLE;
break;
default: {
register int len;
register char ender;
regparse--;
len = strcspn(regparse, META);
if (len <= 0)
FAIL("internal disaster");
ender = *(regparse+len);
if (len > 1 && ISMULT(ender))
len--; /* Back off clear of ?+* operand. */
*flagp |= HASWIDTH;
if (len == 1)
*flagp |= SIMPLE;
ret = tweb_regnode(EXACTLY);
while (len > 0) {
tweb_regc(*regparse++);
len--;
}
tweb_regc('\0');
}
break;
}
return(ret);
}
/*
- tweb_regnode - emit a node
*/
PRIVATE char * tweb_regnode(op)
char op;
{
register char *ret;
register char *ptr;
ret = regcode;
if (ret == &regdummy) {
regsize += 3;
return(ret);
}
ptr = ret;
*ptr++ = op;
*ptr++ = '\0'; /* Null "next" pointer. */
*ptr++ = '\0';
regcode = ptr;
return(ret);
}
/*
- regc - emit (if appropriate) a byte of code
*/
PRIVATE void tweb_regc(b)
char b;
{
if (regcode != &regdummy)
*regcode++ = b;
else
regsize++;
}
/*
- tweb_reginsert - insert an operator in front of already-emitted operand
*
* Means relocating the operand.
*/
PRIVATE void tweb_reginsert(op, opnd)
char op;
char *opnd;
{
register char *src;
register char *dst;
register char *place;
if (regcode == &regdummy) {
regsize += 3;
return;
}
src = regcode;
regcode += 3;
dst = regcode;
while (src > opnd)
*--dst = *--src;
place = opnd; /* Op node, where operand used to be. */
*place++ = op;
*place++ = '\0';
*place++ = '\0';
}
/*
- tweb_regtail - set the next-pointer at the end of a node chain
*/
PRIVATE void tweb_regtail(p, val)
char *p;
char *val;
{
register char *scan;
register char *temp;
register int offset;
if (p == &regdummy)
return;
/* Find last node. */
scan = p;
for (;;) {
temp = tweb_regnext(scan);
if (temp == NULL)
break;
scan = temp;
}
if (OP(scan) == BACK)
offset = scan - val;
else
offset = val - scan;
*(scan+1) = (offset>>8)&0377;
*(scan+2) = offset&0377;
}
/*
- tweb_regoptail - tweb_regtail on operand of first argument; nop if operandless
*/
PRIVATE void tweb_regoptail(p, val)
char *p;
char *val;
{
/* "Operandless" and "op != BRANCH" are synonymous in practice. */
if (p == NULL || p == &regdummy || OP(p) != BRANCH)
return;
tweb_regtail(OPERAND(p), val);
}
/*
* tweb_regexec and friends
*/
/*
* Global work variables for tweb_regexec().
*/
static char *reginput; /* String-input pointer. */
static char *regbol; /* Beginning of input, for ^ check. */
static char **regstartp; /* Pointer to startp array. */
static char **regendp; /* Ditto for endp. */
/*
* Forwards.
*/
STATIC int tweb_regtry();
STATIC int tweb_regmatch();
STATIC int tweb_regrepeat();
#ifdef DEBUG
int regnarrate = 0;
void tweb_regdump();
STATIC char *tweb_regprop();
#endif
/*
- tweb_regexec - match a regexp against a string
*/
int
PUBLIC tweb_regexec(prog, string)
register regexp *prog;
register char *string;
{
register char *s;
extern char *strchr();
/* Be paranoid... */
if (prog == NULL || string == NULL) {
tweb_regerror("NULL parameter");
return(0);
}
/* Check validity of program. */
if (UCHARAT(prog->program) != MAGIC) {
tweb_regerror("corrupted program");
return(0);
}
/* If there is a "must appear" string, look for it. */
if (prog->regmust != NULL) {
s = string;
while ((s = strchr(s, prog->regmust[0])) != NULL) {
if (strncmp(s, prog->regmust, prog->regmlen) == 0)
break; /* Found it. */
s++;
}
if (s == NULL) /* Not present. */
return(0);
}
/* Mark beginning of line for ^ . */
regbol = string;
/* Simplest case: anchored match need be tried only once. */
if (prog->reganch)
return(tweb_regtry(prog, string));
/* Messy cases: unanchored match. */
s = string;
if (prog->regstart != '\0')
/* We know what char it must start with. */
while ((s = strchr(s, prog->regstart)) != NULL) {
if (tweb_regtry(prog, s))
return(1);
s++;
}
else
/* We don't -- general case. */
do {
if (tweb_regtry(prog, s))
return(1);
} while (*s++ != '\0');
/* Failure. */
return(0);
}
/*
- tweb_regtry - try match at specific point
*/
PRIVATE int tweb_regtry(prog, string)
regexp *prog;
char *string;
{
register int i;
register char **sp;
register char **ep;
reginput = string;
regstartp = prog->startp;
regendp = prog->endp;
sp = prog->startp;
ep = prog->endp;
for (i = NSUBEXP; i > 0; i--) {
*sp++ = NULL;
*ep++ = NULL;
}
if (tweb_regmatch(prog->program + 1)) {
prog->startp[0] = string;
prog->endp[0] = reginput;
return(1);
} else
return(0);
}
/*
- tweb_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.
*/
PRIVATE int tweb_regmatch(prog)
char *prog;
{
register char *scan; /* Current node. */
char *next; /* Next node. */
extern char *strchr();
scan = prog;
#ifdef DEBUG
if (scan != NULL && regnarrate)
fprintf(stderr, "%s(\n", tweb_regprop(scan));
#endif
while (scan != NULL) {
#ifdef DEBUG
if (regnarrate)
fprintf(stderr, "%s...\n", tweb_regprop(scan));
#endif
next = tweb_regnext(scan);
switch (OP(scan)) {
case BOL:
if (reginput != regbol)
return(0);
break;
case EOL:
if (*reginput != '\0')
return(0);
break;
case ANY:
if (*reginput == '\0')
return(0);
reginput++;
break;
case EXACTLY: {
register int len;
register char *opnd;
opnd = OPERAND(scan);
/* Inline the first character, for speed. */
if (*opnd != *reginput)
return(0);
len = strlen(opnd);
if (len > 1 && strncmp(opnd, reginput, len) != 0)
return(0);
reginput += len;
}
break;
case ANYOF:
if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) == NULL)
return(0);
reginput++;
break;
case ANYBUT:
if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != NULL)
return(0);
reginput++;
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: {
register int no;
register char *save;
no = OP(scan) - OPEN;
save = reginput;
if (tweb_regmatch(next)) {
/*
* Don't set startp if some later
* invocation of the same parentheses
* already has.
*/
if (regstartp[no] == NULL)
regstartp[no] = save;
return(1);
} else
return(0);
}
break;
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: {
register int no;
register char *save;
no = OP(scan) - CLOSE;
save = reginput;
if (tweb_regmatch(next)) {
/*
* Don't set endp if some later
* invocation of the same parentheses
* already has.
*/
if (regendp[no] == NULL)
regendp[no] = save;
return(1);
} else
return(0);
}
break;
case BRANCH: {
register char *save;
if (OP(next) != BRANCH) /* No choice. */
next = OPERAND(scan); /* Avoid recursion. */
else {
do {
save = reginput;
if (tweb_regmatch(OPERAND(scan)))
return(1);
reginput = save;
scan = tweb_regnext(scan);
} while (scan != NULL && OP(scan) == BRANCH);
return(0);
/* NOTREACHED */
}
}
break;
case STAR:
case PLUS: {
register char nextch;
register int no;
register char *save;
register int min;
/*
* Lookahead to avoid useless match attempts
* when we know what character comes next.
*/
nextch = '\0';
if (OP(next) == EXACTLY)
nextch = *OPERAND(next);
min = (OP(scan) == STAR) ? 0 : 1;
save = reginput;
no = tweb_regrepeat(OPERAND(scan));
while (no >= min) {
/* If it could work, try it. */
if (nextch == '\0' || *reginput == nextch)
if (tweb_regmatch(next))
return(1);
/* Couldn't or didn't -- back up. */
no--;
reginput = save + no;
}
return(0);
}
break;
case END:
return(1); /* Success! */
break;
default:
tweb_regerror("memory corruption");
return(0);
break;
}
scan = next;
}
/*
* We get here only if there's trouble -- normally "case END" is
* the terminating point.
*/
tweb_regerror("corrupted pointers");
return(0);
}
/*
- tweb_regrepeat - repeatedly match something simple, report how many
*/
PRIVATE int tweb_regrepeat(p)
char *p;
{
register int count = 0;
register char *scan;
register char *opnd;
extern char *strchr();
scan = reginput;
opnd = OPERAND(p);
switch (OP(p)) {
case ANY:
count = strlen(scan);
scan += count;
break;
case EXACTLY:
while (*opnd == *scan) {
count++;
scan++;
}
break;
case ANYOF:
while (*scan != '\0' && strchr(opnd, *scan) != NULL) {
count++;
scan++;
}
break;
case ANYBUT:
while (*scan != '\0' && strchr(opnd, *scan) == NULL) {
count++;
scan++;
}
break;
default: /* Oh dear. Called inappropriately. */
tweb_regerror("internal foulup");
count = 0; /* Best compromise. */
break;
}
reginput = scan;
return(count);
}
/*
- tweb_regnext - dig the "next" pointer out of a node
*/
PRIVATE char * tweb_regnext(p)
register char *p;
{
register int offset;
if (p == &regdummy)
return(NULL);
offset = NEXT(p);
if (offset == 0)
return(NULL);
if (OP(p) == BACK)
return(p-offset);
else
return(p+offset);
}
#ifdef DEBUG
PRIVATE char *tweb_regprop();
/*
- tweb_regdump - dump a regexp onto stdout in vaguely comprehensible form
*/
PUBLIC void tweb_regdump(r)
regexp *r;
{
register char *s;
register char op = EXACTLY; /* Arbitrary non-END op. */
register char *next;
extern char *strchr();
s = r->program + 1;
while (op != END) { /* While that wasn't END last time... */
op = OP(s);
printf("%2d%s", s-r->program, tweb_regprop(s)); /* Where, what. */
next = tweb_regnext(s);
if (next == NULL) /* Next ptr. */
printf("(0)");
else
printf("(%d)", (s-r->program)+(next-s));
s += 3;
if (op == ANYOF || op == ANYBUT || op == EXACTLY) {
/* Literal string, where present. */
while (*s != '\0') {
putchar(*s);
s++;
}
s++;
}
putchar('\n');
}
/* Header fields of interest. */
if (r->regstart != '\0')
printf("start `%c' ", r->regstart);
if (r->reganch)
printf("anchored ");
if (r->regmust != NULL)
printf("must have \"%s\"", r->regmust);
printf("\n");
}
/*
- tweb_regprop - printable representation of opcode
*/
PRIVATE char * tweb_regprop(op)
char *op;
{
register char *p;
static char buf[50];
(void) strcpy(buf, ":");
switch (OP(op)) {
case BOL:
p = "BOL";
break;
case EOL:
p = "EOL";
break;
case ANY:
p = "ANY";
break;
case ANYOF:
p = "ANYOF";
break;
case ANYBUT:
p = "ANYBUT";
break;
case BRANCH:
p = "BRANCH";
break;
case EXACTLY:
p = "EXACTLY";
break;
case NOTHING:
p = "NOTHING";
break;
case BACK:
p = "BACK";
break;
case END:
p = "END";
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:
sprintf(buf+strlen(buf), "OPEN%d", OP(op)-OPEN);
p = NULL;
break;
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:
sprintf(buf+strlen(buf), "CLOSE%d", OP(op)-CLOSE);
p = NULL;
break;
case STAR:
p = "STAR";
break;
case PLUS:
p = "PLUS";
break;
default:
tweb_regerror("corrupted opcode");
break;
}
if (p != NULL)
(void) strcat(buf, p);
return(buf);
}
#endif
/*
* The following is provided for those people who do not have strcspn() in
* their C libraries. They should get off their butts and do something
* about it; at least one public-domain implementation of those (highly
* useful) string routines has been published on Usenet.
*/
#ifdef strcspn
/*
* strcspn - find length of initial segment of s1 consisting entirely
* of characters not from s2
*/
PRIVATE int strcspn(s1, s2)
char *s1;
char *s2;
{
register char *scan1;
register char *scan2;
register int count;
count = 0;
for (scan1 = s1; *scan1 != '\0'; scan1++) {
for (scan2 = s2; *scan2 != '\0';) /* ++ moved down. */
if (*scan1 == *scan2++)
return(count);
count++;
}
return(count);
}
#endif
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