regex.c

vc环境下的pgp源码

					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)) != 0)
				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) != 0 && 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)) != 0)
					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++) != 0) {
		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]) != 0 && (ep = eopat[pin]) != 0) {
			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 */