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openldap/libraries/libldap/regex.c
Kurt Zeilenga 42e0d83cb3 Initial revision
1998-08-09 00:43:13 +00:00

907 lines
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#include "portable.h"
#if defined( MACOS ) || defined( DOS ) || defined( _WIN32 ) || defined( NEED_BSDREGEX )
#include "regex.h"
/*
* regex - Regular expression pattern matching and replacement
*
* By: Ozan S. Yigit (oz)
* Dept. of Computer Science
* York University
*
* These routines are the PUBLIC DOMAIN equivalents of regex
* routines as found in 4.nBSD UN*X, with minor extensions.
*
* These routines are derived from various implementations found
* in software tools books, and Conroy's grep. They are NOT derived
* from licensed/restricted software.
* For more interesting/academic/complicated implementations,
* see Henry Spencer's regexp routines, or GNU Emacs pattern
* matching module.
*
* Modification history:
*
* $Log: regex.c,v $
* Revision 1.12 1996/04/25 16:20:59 mcs
* make re_exec() match "" with ".*" and similar patterns
* hopefully this change doesn't break anything else!
*
* Revision 1.11 1994/12/14 21:33:45 mcs
* use new NEED_BSDREGEX
* fix pmatch() prototype
*
* Revision 1.10 1994/12/12 18:16:39 mcs
* use on NetBSD
*
* Revision 1.9 1994/11/15 19:16:35 mcs
* add (CHAR) cast to make VisualC++ happy
*
* Revision 1.8 1994/11/08 21:14:32 mcs
* WIN32 changes
*
* Revision 1.7 1994/07/23 19:51:24 mcs
* use ANSI-style inline function parameters
*
* Revision 1.6 1993/10/18 01:52:32 tim
* include for VMS
*
* Revision 1.5 1993/09/28 21:37:54 mcs
* HP/UX needs the regex we include (not in its libc)
*
* Revision 1.4 1993/08/27 15:59:52 mcs
* use CHAR for deftab
*
* Revision 1.3 1993/08/27 15:49:47 mcs
* added missing 0 to octal constants
* use unsigned char for CHAR under DOS
*
* Revision 1.2 1993/08/27 14:57:48 mcs
* add proto. for pmatch
*
* Revision 1.1 1993/08/18 21:20:02 mcs
* Initial revision
*
* Revision 1.4 1991/10/17 03:56:42 oz
* miscellaneous changes, small cleanups etc.
*
* Revision 1.3 1989/04/01 14:18:09 oz
* Change all references to a dfa: this is actually an nfa.
*
* Revision 1.2 88/08/28 15:36:04 oz
* Use a complement bitmap to represent NCL.
* This removes the need to have seperate
* code in the pmatch case block - it is
* just CCL code now.
*
* Use the actual CCL code in the CLO
* section of pmatch. No need for a recursive
* pmatch call.
*
* Use a bitmap table to set char bits in an
* 8-bit chunk.
*
* Interfaces:
* re_comp: compile a regular expression into a NFA.
*
* char *re_comp(s)
* char *s;
*
* re_exec: execute the NFA to match a pattern.
*
* int re_exec(s)
* char *s;
*
* re_modw change re_exec's understanding of what a "word"
* looks like (for \< and \>) by adding into the
* hidden word-syntax table.
*
* void re_modw(s)
* char *s;
*
* re_subs: substitute the matched portions in a new string.
*
* int re_subs(src, dst)
* char *src;
* char *dst;
*
* re_fail: failure routine for re_exec.
*
* void re_fail(msg, op)
* char *msg;
* char op;
*
* Regular Expressions:
*
* [1] char matches itself, unless it is a special
* character (metachar): . \ [ ] * + ^ $
*
* [2] . matches any character.
*
* [3] \ matches the character following it, except
* when followed by a left or right round bracket,
* a digit 1 to 9 or a left or right angle bracket.
* (see [7], [8] and [9])
* It is used as an escape character for all
* other meta-characters, and itself. When used
* in a set ([4]), it is treated as an ordinary
* character.
*
* [4] [set] matches one of the characters in the set.
* If the first character in the set is "^",
* it matches a character NOT in the set, i.e.
* complements the set. A shorthand S-E is
* used to specify a set of characters S upto
* E, inclusive. The special characters "]" and
* "-" have no special meaning if they appear
* as the first chars in the set.
* examples: match:
*
* [a-z] any lowercase alpha
*
* [^]-] any char except ] and -
*
* [^A-Z] any char except uppercase
* alpha
*
* [a-zA-Z] any alpha
*
* [5] * any regular expression form [1] to [4], followed by
* closure char (*) matches zero or more matches of
* that form.
*
* [6] + same as [5], except it matches one or more.
*
* [7] a regular expression in the form [1] to [10], enclosed
* as \(form\) matches what form matches. The enclosure
* creates a set of tags, used for [8] and for
* pattern substution. The tagged forms are numbered
* starting from 1.
*
* [8] a \ followed by a digit 1 to 9 matches whatever a
* previously tagged regular expression ([7]) matched.
*
* [9] \< a regular expression starting with a \< construct
* \> and/or ending with a \> construct, restricts the
* pattern matching to the beginning of a word, and/or
* the end of a word. A word is defined to be a character
* string beginning and/or ending with the characters
* A-Z a-z 0-9 and _. It must also be preceded and/or
* followed by any character outside those mentioned.
*
* [10] a composite regular expression xy where x and y
* are in the form [1] to [10] matches the longest
* match of x followed by a match for y.
*
* [11] ^ a regular expression starting with a ^ character
* $ and/or ending with a $ character, restricts the
* pattern matching to the beginning of the line,
* or the end of line. [anchors] Elsewhere in the
* pattern, ^ and $ are treated as ordinary characters.
*
*
* Acknowledgements:
*
* HCR's Hugh Redelmeier has been most helpful in various
* stages of development. He convinced me to include BOW
* and EOW constructs, originally invented by Rob Pike at
* the University of Toronto.
*
* References:
* Software tools Kernighan & Plauger
* Software tools in Pascal Kernighan & Plauger
* Grep [rsx-11 C dist] David Conroy
* ed - text editor Un*x Programmer's Manual
* Advanced editing on Un*x B. W. Kernighan
* RegExp routines Henry Spencer
*
* Notes:
*
* This implementation uses a bit-set representation for character
* classes for speed and compactness. Each character is represented
* by one bit in a 128-bit block. Thus, CCL always takes a
* constant 16 bytes in the internal nfa, and re_exec does a single
* bit comparison to locate the character in the set.
*
* Examples:
*
* pattern: foo*.*
* compile: CHR f CHR o CLO CHR o END CLO ANY END END
* matches: fo foo fooo foobar fobar foxx ...
*
* pattern: fo[ob]a[rz]
* compile: CHR f CHR o CCL bitset CHR a CCL bitset END
* matches: fobar fooar fobaz fooaz
*
* pattern: foo\\+
* compile: CHR f CHR o CHR o CHR \ CLO CHR \ END END
* matches: foo\ foo\\ foo\\\ ...
*
* pattern: \(foo\)[1-3]\1 (same as foo[1-3]foo)
* compile: BOT 1 CHR f CHR o CHR o EOT 1 CCL bitset REF 1 END
* matches: foo1foo foo2foo foo3foo
*
* pattern: \(fo.*\)-\1
* compile: BOT 1 CHR f CHR o CLO ANY END EOT 1 CHR - REF 1 END
* matches: foo-foo fo-fo fob-fob foobar-foobar ...
*/
#define MAXNFA 1024
#define MAXTAG 10
#define OKP 1
#define NOP 0
#define CHR 1
#define ANY 2
#define CCL 3
#define BOL 4
#define EOL 5
#define BOT 6
#define EOT 7
#define BOW 8
#define EOW 9
#define REF 10
#define CLO 11
#define END 0
/*
* The following defines are not meant to be changeable.
* They are for readability only.
*/
#define MAXCHR 128
#define CHRBIT 8
#define BITBLK MAXCHR/CHRBIT
#define BLKIND 0170
#define BITIND 07
#define ASCIIB 0177
#if defined( DOS ) || defined( _WIN32 )
typedef unsigned char CHAR;
#else /* DOS */
typedef /*unsigned*/ char CHAR;
#endif /* DOS */
static int tagstk[MAXTAG]; /* subpat tag stack..*/
static CHAR nfa[MAXNFA]; /* automaton.. */
static int sta = NOP; /* status of lastpat */
static CHAR bittab[BITBLK]; /* bit table for CCL */
/* pre-set bits... */
static CHAR bitarr[] = {1,2,4,8,16,32,64,128};
static void
chset(CHAR c)
{
bittab[((c) & BLKIND) >> 3] |= bitarr[(c) & BITIND];
}
#define badpat(x) (*nfa = END, x)
#define store(x) *mp++ = x
char *
re_comp( char *pat )
{
register char *p; /* pattern pointer */
register CHAR *mp=nfa; /* nfa pointer */
register CHAR *lp; /* saved pointer.. */
register CHAR *sp=nfa; /* another one.. */
register int tagi = 0; /* tag stack index */
register int tagc = 1; /* actual tag count */
register int n;
register CHAR mask; /* xor mask -CCL/NCL */
int c1, c2;
if (!pat || !*pat)
if (sta)
return 0;
else
return badpat("No previous regular expression");
sta = NOP;
for (p = pat; *p; p++) {
lp = mp;
switch(*p) {
case '.': /* match any char.. */
store(ANY);
break;
case '^': /* match beginning.. */
if (p == pat)
store(BOL);
else {
store(CHR);
store(*p);
}
break;
case '$': /* match endofline.. */
if (!*(p+1))
store(EOL);
else {
store(CHR);
store(*p);
}
break;
case '[': /* match char class..*/
store(CCL);
if (*++p == '^') {
mask = 0377;
p++;
}
else
mask = 0;
if (*p == '-') /* real dash */
chset(*p++);
if (*p == ']') /* real brac */
chset(*p++);
while (*p && *p != ']') {
if (*p == '-' && *(p+1) && *(p+1) != ']') {
p++;
c1 = *(p-2) + 1;
c2 = *p++;
while (c1 <= c2)
chset((CHAR)c1++);
}
#ifdef EXTEND
else if (*p == '\\' && *(p+1)) {
p++;
chset(*p++);
}
#endif
else
chset(*p++);
}
if (!*p)
return badpat("Missing ]");
for (n = 0; n < BITBLK; bittab[n++] = (char) 0)
store(mask ^ bittab[n]);
break;
case '*': /* match 0 or more.. */
case '+': /* match 1 or more.. */
if (p == pat)
return badpat("Empty closure");
lp = sp; /* previous opcode */
if (*lp == CLO) /* equivalence.. */
break;
switch(*lp) {
case BOL:
case BOT:
case EOT:
case BOW:
case EOW:
case REF:
return badpat("Illegal closure");
default:
break;
}
if (*p == '+')
for (sp = mp; lp < sp; lp++)
store(*lp);
store(END);
store(END);
sp = mp;
while (--mp > lp)
*mp = mp[-1];
store(CLO);
mp = sp;
break;
case '\\': /* tags, backrefs .. */
switch(*++p) {
case '(':
if (tagc < MAXTAG) {
tagstk[++tagi] = tagc;
store(BOT);
store(tagc++);
}
else
return badpat("Too many \\(\\) pairs");
break;
case ')':
if (*sp == BOT)
return badpat("Null pattern inside \\(\\)");
if (tagi > 0) {
store(EOT);
store(tagstk[tagi--]);
}
else
return badpat("Unmatched \\)");
break;
case '<':
store(BOW);
break;
case '>':
if (*sp == BOW)
return badpat("Null pattern inside \\<\\>");
store(EOW);
break;
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
n = *p-'0';
if (tagi > 0 && tagstk[tagi] == n)
return badpat("Cyclical reference");
if (tagc > n) {
store(REF);
store(n);
}
else
return badpat("Undetermined reference");
break;
#ifdef EXTEND
case 'b':
store(CHR);
store('\b');
break;
case 'n':
store(CHR);
store('\n');
break;
case 'f':
store(CHR);
store('\f');
break;
case 'r':
store(CHR);
store('\r');
break;
case 't':
store(CHR);
store('\t');
break;
#endif
default:
store(CHR);
store(*p);
}
break;
default : /* an ordinary char */
store(CHR);
store(*p);
break;
}
sp = lp;
}
if (tagi > 0)
return badpat("Unmatched \\(");
store(END);
sta = OKP;
return 0;
}
static char *bol;
char *bopat[MAXTAG];
char *eopat[MAXTAG];
#ifdef NEEDPROTOS
static char *pmatch( char *lp, CHAR *ap );
#else /* NEEDPROTOS */
static char *pmatch();
#endif /* NEEDPROTOS */
/*
* re_exec:
* execute nfa to find a match.
*
* special cases: (nfa[0])
* BOL
* Match only once, starting from the
* beginning.
* CHR
* First locate the character without
* calling pmatch, and if found, call
* pmatch for the remaining string.
* END
* re_comp failed, poor luser did not
* check for it. Fail fast.
*
* If a match is found, bopat[0] and eopat[0] are set
* to the beginning and the end of the matched fragment,
* respectively.
*
*/
int
re_exec( char *lp )
{
register char c;
register char *ep = 0;
register CHAR *ap = nfa;
bol = lp;
bopat[0] = 0;
bopat[1] = 0;
bopat[2] = 0;
bopat[3] = 0;
bopat[4] = 0;
bopat[5] = 0;
bopat[6] = 0;
bopat[7] = 0;
bopat[8] = 0;
bopat[9] = 0;
switch(*ap) {
case BOL: /* anchored: match from BOL only */
ep = pmatch(lp,ap);
break;
case CHR: /* ordinary char: locate it fast */
c = *(ap+1);
while (*lp && *lp != c)
lp++;
if (!*lp) /* if EOS, fail, else fall thru. */
return 0;
default: /* regular matching all the way. */
do {
if ((ep = pmatch(lp,ap)))
break;
lp++;
} while (*lp);
break;
case END: /* munged automaton. fail always */
return 0;
}
if (!ep)
return 0;
bopat[0] = lp;
eopat[0] = ep;
return 1;
}
/*
* pmatch: internal routine for the hard part
*
* This code is partly snarfed from an early grep written by
* David Conroy. The backref and tag stuff, and various other
* innovations are by oz.
*
* special case optimizations: (nfa[n], nfa[n+1])
* CLO ANY
* We KNOW .* will match everything upto the
* end of line. Thus, directly go to the end of
* line, without recursive pmatch calls. As in
* the other closure cases, the remaining pattern
* must be matched by moving backwards on the
* string recursively, to find a match for xy
* (x is ".*" and y is the remaining pattern)
* where the match satisfies the LONGEST match for
* x followed by a match for y.
* CLO CHR
* We can again scan the string forward for the
* single char and at the point of failure, we
* execute the remaining nfa recursively, same as
* above.
*
* At the end of a successful match, bopat[n] and eopat[n]
* are set to the beginning and end of subpatterns matched
* by tagged expressions (n = 1 to 9).
*
*/
#ifndef re_fail
extern void re_fail();
#endif /* re_fail */
/*
* character classification table for word boundary operators BOW
* and EOW. the reason for not using ctype macros is that we can
* let the user add into our own table. see re_modw. This table
* is not in the bitset form, since we may wish to extend it in the
* future for other character classifications.
*
* TRUE for 0-9 A-Z a-z _
*/
static char chrtyp[MAXCHR] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 0, 0, 0, 0, 1, 0, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 0, 0, 0, 0, 0
};
#define inascii(x) (0177&(x))
#define iswordc(x) chrtyp[inascii(x)]
#define isinset(x,y) ((x)[((y)&BLKIND)>>3] & bitarr[(y)&BITIND])
/*
* skip values for CLO XXX to skip past the closure
*/
#define ANYSKIP 2 /* [CLO] ANY END ... */
#define CHRSKIP 3 /* [CLO] CHR chr END ... */
#define CCLSKIP 18 /* [CLO] CCL 16bytes END ... */
static char *
pmatch( char *lp, CHAR *ap)
{
register int op, c, n;
register char *e; /* extra pointer for CLO */
register char *bp; /* beginning of subpat.. */
register char *ep; /* ending of subpat.. */
char *are; /* to save the line ptr. */
while ((op = *ap++) != END)
switch(op) {
case CHR:
if (*lp++ != *ap++)
return 0;
break;
case ANY:
if (!*lp++)
return 0;
break;
case CCL:
c = *lp++;
if (!isinset(ap,c))
return 0;
ap += BITBLK;
break;
case BOL:
if (lp != bol)
return 0;
break;
case EOL:
if (*lp)
return 0;
break;
case BOT:
bopat[*ap++] = lp;
break;
case EOT:
eopat[*ap++] = lp;
break;
case BOW:
if (lp!=bol && iswordc(lp[-1]) || !iswordc(*lp))
return 0;
break;
case EOW:
if (lp==bol || !iswordc(lp[-1]) || iswordc(*lp))
return 0;
break;
case REF:
n = *ap++;
bp = bopat[n];
ep = eopat[n];
while (bp < ep)
if (*bp++ != *lp++)
return 0;
break;
case CLO:
are = lp;
switch(*ap) {
case ANY:
while (*lp)
lp++;
n = ANYSKIP;
break;
case CHR:
c = *(ap+1);
while (*lp && c == *lp)
lp++;
n = CHRSKIP;
break;
case CCL:
while ((c = *lp) && isinset(ap+1,c))
lp++;
n = CCLSKIP;
break;
default:
re_fail("closure: bad nfa.", *ap);
return 0;
}
ap += n;
while (lp >= are) {
if (e = pmatch(lp, ap))
return e;
--lp;
}
return 0;
default:
re_fail("re_exec: bad nfa.", op);
return 0;
}
return lp;
}
/*
* re_modw:
* add new characters into the word table to change re_exec's
* understanding of what a word should look like. Note that we
* only accept additions into the word definition.
*
* If the string parameter is 0 or null string, the table is
* reset back to the default containing A-Z a-z 0-9 _. [We use
* the compact bitset representation for the default table]
*/
static CHAR deftab[16] = {
0, 0, 0, 0, 0, 0, 0377, 003, 0376, 0377, 0377, 0207,
0376, 0377, 0377, 007
};
void
re_modw( char *s )
{
register int i;
if (!s || !*s) {
for (i = 0; i < MAXCHR; i++)
if (!isinset(deftab,i))
iswordc(i) = 0;
}
else
while(*s)
iswordc(*s++) = 1;
}
/*
* re_subs:
* substitute the matched portions of the src in dst.
*
* & substitute the entire matched pattern.
*
* \digit substitute a subpattern, with the given tag number.
* Tags are numbered from 1 to 9. If the particular
* tagged subpattern does not exist, null is substituted.
*/
int
re_subs( char *src, char *dst)
{
register char c;
register int pin;
register char *bp;
register char *ep;
if (!*src || !bopat[0])
return 0;
while (c = *src++) {
switch(c) {
case '&':
pin = 0;
break;
case '\\':
c = *src++;
if (c >= '0' && c <= '9') {
pin = c - '0';
break;
}
default:
*dst++ = c;
continue;
}
if ((bp = bopat[pin]) && (ep = eopat[pin])) {
while (*bp && bp < ep)
*dst++ = *bp++;
if (bp < ep)
return 0;
}
}
*dst = (char) 0;
return 1;
}
#ifdef DEBUG
/*
* symbolic - produce a symbolic dump of the nfa
*/
symbolic( char *s )
{
printf("pattern: %s\n", s);
printf("nfacode:\n");
nfadump(nfa);
}
static
nfadump( CHAR *ap)
{
register int n;
while (*ap != END)
switch(*ap++) {
case CLO:
printf("CLOSURE");
nfadump(ap);
switch(*ap) {
case CHR:
n = CHRSKIP;
break;
case ANY:
n = ANYSKIP;
break;
case CCL:
n = CCLSKIP;
break;
}
ap += n;
break;
case CHR:
printf("\tCHR %c\n",*ap++);
break;
case ANY:
printf("\tANY .\n");
break;
case BOL:
printf("\tBOL -\n");
break;
case EOL:
printf("\tEOL -\n");
break;
case BOT:
printf("BOT: %d\n",*ap++);
break;
case EOT:
printf("EOT: %d\n",*ap++);
break;
case BOW:
printf("BOW\n");
break;
case EOW:
printf("EOW\n");
break;
case REF:
printf("REF: %d\n",*ap++);
break;
case CCL:
printf("\tCCL [");
for (n = 0; n < MAXCHR; n++)
if (isinset(ap,(CHAR)n)) {
if (n < ' ')
printf("^%c", n ^ 0x040);
else
printf("%c", n);
}
printf("]\n");
ap += BITBLK;
break;
default:
printf("bad nfa. opcode %o\n", ap[-1]);
exit(1);
break;
}
}
#endif
#endif /* MACOS or DOS or NEED_BSDREGEX */
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