regexp.h

来自「这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易」· C头文件 代码 · 共 411 行

#define	CBRA	2
#define	CCHR	4
#define	CDOT	8
#define	CCL	12
#define	CDOL	20
#define	CEOF	22
#define	CKET	24
#define	CBACK	36

#define	STAR	01
#define RNGE	03

#define	NBRA	9

#define PLACE(c)	ep[c >> 3] |= bittab[c & 07]
#define ISTHERE(c)	(ep[c >> 3] & bittab[c & 07])

char	*braslist[NBRA];
char	*braelist[NBRA];
int	nbra, ebra;
char *loc1, *loc2, *locs;
int	sed;

int	circf;
int	low;
int	size;

char	bittab[] = {
	1,
	2,
	4,
	8,
	16,
	32,
	64,
	128
};

char *
compile(instring, ep, endbuf, seof)
register char *ep;
char *instring, *endbuf;
{
	INIT	/* Dependent declarations and initializations */
	register c;
	register eof = seof;
	char *lastep = instring;
	int cclcnt;
	char bracket[NBRA], *bracketp;
	int closed;
	char neg;
	int lc;
	int i, cflg;

	lastep = 0;
	if((c = GETC()) == eof) {
		if(*ep == 0 && !sed)
			ERROR(41);
		RETURN(ep);
	}
	bracketp = bracket;
	circf = closed = nbra = ebra = 0;
	if (c == '^')
		circf++;
	else
		UNGETC(c);
	for (;;) {
		if (ep >= endbuf)
			ERROR(50);
		if((c = GETC()) != '*' && ((c != '\\') || (PEEKC() != '{')))
			lastep = ep;
		if (c == eof) {
			*ep++ = CEOF;
			RETURN(ep);
		}
		switch (c) {

		case '.':
			*ep++ = CDOT;
			continue;

		case '\n':
			ERROR(36);
		case '*':
			if (lastep==0 || *lastep==CBRA || *lastep==CKET)
				goto defchar;
			*lastep |= STAR;
			continue;

		case '$':
			if(PEEKC() != eof)
				goto defchar;
			*ep++ = CDOL;
			continue;

		case '[':
			if(&ep[17] >= endbuf)
				ERROR(50);

			*ep++ = CCL;
			lc = 0;
			for(i = 0; i < 16; i++)
				ep[i] = 0;

			neg = 0;
			if((c = GETC()) == '^') {
				neg = 1;
				c = GETC();
			}

			do {
				if(c == '\0' || c == '\n')
					ERROR(49);
				if(c == '-' && lc != 0) {
					if ((c = GETC()) == ']') {
						PLACE('-');
						break;
					}
					while(lc < c) {
						PLACE(lc);
						lc++;
					}
				}
				lc = c;
				PLACE(c);
			} while((c = GETC()) != ']');
			if(neg) {
				for(cclcnt = 0; cclcnt < 16; cclcnt++)
					ep[cclcnt] ^= -1;
				ep[0] &= 0376;
			}

			ep += 16;

			continue;

		case '\\':
			switch(c = GETC()) {

			case '(':
				if(nbra >= NBRA)
					ERROR(43);
				*bracketp++ = nbra;
				*ep++ = CBRA;
				*ep++ = nbra++;
				continue;

			case ')':
				if(bracketp <= bracket || ++ebra != nbra)
					ERROR(42);
				*ep++ = CKET;
				*ep++ = *--bracketp;
				closed++;
				continue;

			case '{':
				if(lastep == (char *) (0))
					goto defchar;
				*lastep |= RNGE;
				cflg = 0;
			nlim:
				c = GETC();
				i = 0;
				do {
					if ('0' <= c && c <= '9')
						i = 10 * i + c - '0';
					else
						ERROR(16);
				} while(((c = GETC()) != '\\') && (c != ','));
				if (i > 255)
					ERROR(11);
				*ep++ = i;
				if (c == ',') {
					if(cflg++)
						ERROR(44);
					if((c = GETC()) == '\\')
						*ep++ = 255;
					else {
						UNGETC(c);
						goto nlim; /* get 2'nd number */
					}
				}
				if(GETC() != '}')
					ERROR(45);
				if(!cflg)	/* one number */
					*ep++ = i;
				else if((ep[-1] & 0377) < (ep[-2] & 0377))
					ERROR(46);
				continue;

			case '\n':
				ERROR(36);

			case 'n':
				c = '\n';
				goto defchar;

			default:
				if(c >= '1' && c <= '9') {
					if((c -= '1') >= closed)
						ERROR(25);
					*ep++ = CBACK;
					*ep++ = c;
					continue;
				}
			}
			/* Drop through to default to use \ to turn off special chars */

		defchar:
		default:
			lastep = ep;
			*ep++ = CCHR;
			*ep++ = c;
		}
	}
}

step(p1, p2)
register char *p1, *p2;
{
	register c;

	if (circf) {
		loc1 = p1;
		return(advance(p1, p2));
	}
	/* fast check for first character */
	if (*p2==CCHR) {
		c = p2[1];
		do {
			if (*p1 != c)
				continue;
			if (advance(p1, p2)) {
				loc1 = p1;
				return(1);
			}
		} while (*p1++);
		return(0);
	}
		/* regular algorithm */
	do {
		if (advance(p1, p2)) {
			loc1 = p1;
			return(1);
		}
	} while (*p1++);
	return(0);
}

advance(lp, ep)
register char *lp, *ep;
{
	register char *curlp;
	char c;
	char *bbeg;
	int ct;

	for (;;) switch (*ep++) {

	case CCHR:
		if (*ep++ == *lp++)
			continue;
		return(0);

	case CDOT:
		if (*lp++)
			continue;
		return(0);

	case CDOL:
		if (*lp==0)
			continue;
		return(0);

	case CEOF:
		loc2 = lp;
		return(1);

	case CCL:
		c = *lp++ & 0177;
		if(ISTHERE(c)) {
			ep += 16;
			continue;
		}
		return(0);
	case CBRA:
		braslist[*ep++] = lp;
		continue;

	case CKET:
		braelist[*ep++] = lp;
		continue;

	case CCHR|RNGE:
		c = *ep++;
		getrnge(ep);
		while(low--)
			if(*lp++ != c)
				return(0);
		curlp = lp;
		while(size--) 
			if(*lp++ != c)
				break;
		if(size < 0)
			lp++;
		ep += 2;
		goto star;

	case CDOT|RNGE:
		getrnge(ep);
		while(low--)
			if(*lp++ == '\0')
				return(0);
		curlp = lp;
		while(size--)
			if(*lp++ == '\0')
				break;
		if(size < 0)
			lp++;
		ep += 2;
		goto star;

	case CCL|RNGE:
		getrnge(ep + 16);
		while(low--) {
			c = *lp++ & 0177;
			if(!ISTHERE(c))
				return(0);
		}
		curlp = lp;
		while(size--) {
			c = *lp++ & 0177;
			if(!ISTHERE(c))
				break;
		}
		if(size < 0)
			lp++;
		ep += 18;		/* 16 + 2 */
		goto star;

	case CBACK:
		bbeg = braslist[*ep];
		ct = braelist[*ep++] - bbeg;

		if(ecmp(bbeg, lp, ct)) {
			lp += ct;
			continue;
		}
		return(0);

	case CBACK|STAR:
		bbeg = braslist[*ep];
		ct = braelist[*ep++] - bbeg;
		curlp = lp;
		while(ecmp(bbeg, lp, ct))
			lp += ct;

		while(lp >= curlp) {
			if(advance(lp, ep))	return(1);
			lp -= ct;
		}
		return(0);


	case CDOT|STAR:
		curlp = lp;
		while (*lp++);
		goto star;

	case CCHR|STAR:
		curlp = lp;
		while (*lp++ == *ep);
		ep++;
		goto star;

	case CCL|STAR:
		curlp = lp;
		do {
			c = *lp++ & 0177;
		} while(ISTHERE(c));
		ep += 16;
		goto star;

	star:
		do {
			if(--lp == locs)
				break;
			if (advance(lp, ep))
				return(1);
		} while (lp > curlp);
		return(0);

	}
}

getrnge(str)
register char *str;
{
	low = *str++ & 0377;
	size = *str == 255 ? 20000 : (*str &0377) - low;
}

ecmp(a, b, count)
register char	*a, *b;
register	count;
{
	while(count--)
		if(*a++ != *b++)	return(0);
	return(1);
}