engine.c

regex-spencer-3.8-src.zip

			hard = 1;
			break;
		}
	if (!hard) {		/* that was it! */
		if (sp != stop)
			return(NULL);
		return(sp);
	}
	ss--;			/* adjust for the for's final increment */

	/* the hard stuff */
	AT("hard", sp, stop, ss, stopst);
	s = m->g->strip[ss];
	switch (OP(s)) {
	case OBACK_:		/* the vilest depths */
		i = OPND(s);
		assert(0 < i && i <= m->g->nsub);
		if (m->pmatch[i].rm_eo == -1)
			return(NULL);
		assert(m->pmatch[i].rm_so != -1);
		len = m->pmatch[i].rm_eo - m->pmatch[i].rm_so;
		assert(stop - m->beginp >= len);
		if (sp > stop - len)
			return(NULL);	/* not enough left to match */
		ssp = m->offp + m->pmatch[i].rm_so;
		if (memcmp(sp, ssp, len) != 0)
			return(NULL);
		while (m->g->strip[ss] != SOP(O_BACK, i))
			ss++;
		return(backref(m, sp+len, stop, ss+1, stopst, lev));
		break;
	case OQUEST_:		/* to null or not */
		dp = backref(m, sp, stop, ss+1, stopst, lev);
		if (dp != NULL)
			return(dp);	/* not */
		return(backref(m, sp, stop, ss+OPND(s)+1, stopst, lev));
		break;
	case OPLUS_:
		assert(m->lastpos != NULL);
		assert(lev+1 <= m->g->nplus);
		m->lastpos[lev+1] = sp;
		return(backref(m, sp, stop, ss+1, stopst, lev+1));
		break;
	case O_PLUS:
		if (sp == m->lastpos[lev])	/* last pass matched null */
			return(backref(m, sp, stop, ss+1, stopst, lev-1));
		/* try another pass */
		m->lastpos[lev] = sp;
		dp = backref(m, sp, stop, ss-OPND(s)+1, stopst, lev);
		if (dp == NULL)
			return(backref(m, sp, stop, ss+1, stopst, lev-1));
		else
			return(dp);
		break;
	case OCH_:		/* find the right one, if any */
		ssub = ss + 1;
		esub = ss + OPND(s) - 1;
		assert(OP(m->g->strip[esub]) == OOR1);
		for (;;) {	/* find first matching branch */
			dp = backref(m, sp, stop, ssub, esub, lev);
			if (dp != NULL)
				return(dp);
			/* that one missed, try next one */
			if (OP(m->g->strip[esub]) == O_CH)
				return(NULL);	/* there is none */
			esub++;
			assert(OP(m->g->strip[esub]) == OOR2);
			ssub = esub + 1;
			esub += OPND(m->g->strip[esub]);
			if (OP(m->g->strip[esub]) == OOR2)
				esub--;
			else
				assert(OP(m->g->strip[esub]) == O_CH);
		}
		break;
	case OLPAREN:		/* must undo assignment if rest fails */
		i = OPND(s);
		assert(0 < i && i <= m->g->nsub);
		offsave = m->pmatch[i].rm_so;
		m->pmatch[i].rm_so = sp - m->offp;
		dp = backref(m, sp, stop, ss+1, stopst, lev);
		if (dp != NULL)
			return(dp);
		m->pmatch[i].rm_so = offsave;
		return(NULL);
		break;
	case ORPAREN:		/* must undo assignment if rest fails */
		i = OPND(s);
		assert(0 < i && i <= m->g->nsub);
		offsave = m->pmatch[i].rm_eo;
		m->pmatch[i].rm_eo = sp - m->offp;
		dp = backref(m, sp, stop, ss+1, stopst, lev);
		if (dp != NULL)
			return(dp);
		m->pmatch[i].rm_eo = offsave;
		return(NULL);
		break;
	default:		/* uh oh */
		assert(nope);
		break;
	}

	/* "can't happen" */
	assert(nope);
	/* NOTREACHED */
	return((char *)NULL);	/* dummy */
}

/*
 - fast - step through the string at top speed
 == static char *fast(register struct match *m, char *start, \
 ==	char *stop, sopno startst, sopno stopst);
 */
static char *			/* where tentative match ended, or NULL */
fast(m, start, stop, startst, stopst)
register struct match *m;
char *start;
char *stop;
sopno startst;
sopno stopst;
{
	register states st = m->st;
	register states fresh = m->fresh;
	register states tmp = m->tmp;
	register char *p = start;
	register int c = (start == m->beginp) ? OUT : *(start-1);
	register int lastc;	/* previous c */
	register int flagch;
	register int i;
	register char *coldp;	/* last p after which no match was underway */

	CLEAR(st);
	SET1(st, startst);
	st = step(m->g, startst, stopst, st, NOTHING, st);
	ASSIGN(fresh, st);
	SP("start", st, *p);
	coldp = NULL;
	for (;;) {
		/* next character */
		lastc = c;
		c = (p == m->endp) ? OUT : *p;
		if (EQ(st, fresh))
			coldp = p;

		/* is there an EOL and/or BOL between lastc and c? */
		flagch = '\0';
		i = 0;
		if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
				(lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
			flagch = BOL;
			i = m->g->nbol;
		}
		if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
				(c == OUT && !(m->eflags&REG_NOTEOL)) ) {
			flagch = (flagch == BOL) ? BOLEOL : EOL;
			i += m->g->neol;
		}
		if (i != 0) {
			for (; i > 0; i--)
				st = step(m->g, startst, stopst, st, flagch, st);
			SP("boleol", st, c);
		}

		/* how about a word boundary? */
		if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
					(c != OUT && ISWORD(c)) ) {
			flagch = BOW;
		}
		if ( (lastc != OUT && ISWORD(lastc)) &&
				(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
			flagch = EOW;
		}
		if (flagch == BOW || flagch == EOW) {
			st = step(m->g, startst, stopst, st, flagch, st);
			SP("boweow", st, c);
		}

		/* are we done? */
		if (ISSET(st, stopst) || p == stop)
			break;		/* NOTE BREAK OUT */

		/* no, we must deal with this character */
		ASSIGN(tmp, st);
		ASSIGN(st, fresh);
		assert(c != OUT);
		st = step(m->g, startst, stopst, tmp, c, st);
		SP("aft", st, c);
		assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
		p++;
	}

	assert(coldp != NULL);
	m->coldp = coldp;
	if (ISSET(st, stopst))
		return(p+1);
	else
		return(NULL);
}

/*
 - slow - step through the string more deliberately
 == static char *slow(register struct match *m, char *start, \
 ==	char *stop, sopno startst, sopno stopst);
 */
static char *			/* where it ended */
slow(m, start, stop, startst, stopst)
register struct match *m;
char *start;
char *stop;
sopno startst;
sopno stopst;
{
	register states st = m->st;
	register states empty = m->empty;
	register states tmp = m->tmp;
	register char *p = start;
	register int c = (start == m->beginp) ? OUT : *(start-1);
	register int lastc;	/* previous c */
	register int flagch;
	register int i;
	register char *matchp;	/* last p at which a match ended */

	AT("slow", start, stop, startst, stopst);
	CLEAR(st);
	SET1(st, startst);
	SP("sstart", st, *p);
	st = step(m->g, startst, stopst, st, NOTHING, st);
	matchp = NULL;
	for (;;) {
		/* next character */
		lastc = c;
		c = (p == m->endp) ? OUT : *p;

		/* is there an EOL and/or BOL between lastc and c? */
		flagch = '\0';
		i = 0;
		if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
				(lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
			flagch = BOL;
			i = m->g->nbol;
		}
		if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
				(c == OUT && !(m->eflags&REG_NOTEOL)) ) {
			flagch = (flagch == BOL) ? BOLEOL : EOL;
			i += m->g->neol;
		}
		if (i != 0) {
			for (; i > 0; i--)
				st = step(m->g, startst, stopst, st, flagch, st);
			SP("sboleol", st, c);
		}

		/* how about a word boundary? */
		if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
					(c != OUT && ISWORD(c)) ) {
			flagch = BOW;
		}
		if ( (lastc != OUT && ISWORD(lastc)) &&
				(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
			flagch = EOW;
		}
		if (flagch == BOW || flagch == EOW) {
			st = step(m->g, startst, stopst, st, flagch, st);
			SP("sboweow", st, c);
		}

		/* are we done? */
		if (ISSET(st, stopst))
			matchp = p;
		if (EQ(st, empty) || p == stop)
			break;		/* NOTE BREAK OUT */

		/* no, we must deal with this character */
		ASSIGN(tmp, st);
		ASSIGN(st, empty);
		assert(c != OUT);
		st = step(m->g, startst, stopst, tmp, c, st);
		SP("saft", st, c);
		assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
		p++;
	}

	return(matchp);
}


/*
 - step - map set of states reachable before char to set reachable after
 == static states step(register struct re_guts *g, sopno start, sopno stop, \
 ==	register states bef, int ch, register states aft);
 == #define	BOL	(OUT+1)
 == #define	EOL	(BOL+1)
 == #define	BOLEOL	(BOL+2)
 == #define	NOTHING	(BOL+3)
 == #define	BOW	(BOL+4)
 == #define	EOW	(BOL+5)
 == #define	CODEMAX	(BOL+5)		// highest code used
 == #define	NONCHAR(c)	((c) > CHAR_MAX)
 == #define	NNONCHAR	(CODEMAX-CHAR_MAX)
 */
static states
step(g, start, stop, bef, ch, aft)
register struct re_guts *g;
sopno start;			/* start state within strip */
sopno stop;			/* state after stop state within strip */
register states bef;		/* states reachable before */
int ch;				/* character or NONCHAR code */
register states aft;		/* states already known reachable after */
{
	register cset *cs;
	register sop s;
	register sopno pc;
	register onestate here;		/* note, macros know this name */
	register sopno look;
	register long i;

	for (pc = start, INIT(here, pc); pc != stop; pc++, INC(here)) {
		s = g->strip[pc];
		switch (OP(s)) {
		case OEND:
			assert(pc == stop-1);
			break;
		case OCHAR:
			/* only characters can match */
			assert(!NONCHAR(ch) || ch != (char)OPND(s));
			if (ch == (char)OPND(s))
				FWD(aft, bef, 1);
			break;
		case OBOL:
			if (ch == BOL || ch == BOLEOL)
				FWD(aft, bef, 1);
			break;
		case OEOL:
			if (ch == EOL || ch == BOLEOL)
				FWD(aft, bef, 1);
			break;
		case OBOW:
			if (ch == BOW)
				FWD(aft, bef, 1);
			break;
		case OEOW:
			if (ch == EOW)
				FWD(aft, bef, 1);
			break;
		case OANY:
			if (!NONCHAR(ch))
				FWD(aft, bef, 1);
			break;
		case OANYOF:
			cs = &g->sets[OPND(s)];
			if (!NONCHAR(ch) && CHIN(cs, ch))
				FWD(aft, bef, 1);
			break;
		case OBACK_:		/* ignored here */
		case O_BACK:
			FWD(aft, aft, 1);
			break;
		case OPLUS_:		/* forward, this is just an empty */
			FWD(aft, aft, 1);
			break;
		case O_PLUS:		/* both forward and back */
			FWD(aft, aft, 1);
			i = ISSETBACK(aft, OPND(s));
			BACK(aft, aft, OPND(s));
			if (!i && ISSETBACK(aft, OPND(s))) {
				/* oho, must reconsider loop body */
				pc -= OPND(s) + 1;
				INIT(here, pc);
			}
			break;
		case OQUEST_:		/* two branches, both forward */
			FWD(aft, aft, 1);
			FWD(aft, aft, OPND(s));
			break;
		case O_QUEST:		/* just an empty */
			FWD(aft, aft, 1);
			break;
		case OLPAREN:		/* not significant here */
		case ORPAREN:
			FWD(aft, aft, 1);
			break;
		case OCH_:		/* mark the first two branches */
			FWD(aft, aft, 1);
			assert(OP(g->strip[pc+OPND(s)]) == OOR2);
			FWD(aft, aft, OPND(s));
			break;
		case OOR1:		/* done a branch, find the O_CH */
			if (ISSTATEIN(aft, here)) {
				for (look = 1;
						OP(s = g->strip[pc+look]) != O_CH;
						look += OPND(s))
					assert(OP(s) == OOR2);
				FWD(aft, aft, look);
			}
			break;
		case OOR2:		/* propagate OCH_'s marking */
			FWD(aft, aft, 1);
			if (OP(g->strip[pc+OPND(s)]) != O_CH) {
				assert(OP(g->strip[pc+OPND(s)]) == OOR2);
				FWD(aft, aft, OPND(s));
			}
			break;
		case O_CH:		/* just empty */
			FWD(aft, aft, 1);
			break;
		default:		/* ooooops... */
			assert(nope);
			break;
		}
	}

	return(aft);
}

#ifdef REDEBUG
/*
 - print - print a set of states
 == #ifdef REDEBUG
 == static void print(struct match *m, char *caption, states st, \
 ==	int ch, FILE *d);
 == #endif
 */
static void
print(m, caption, st, ch, d)
struct match *m;
char *caption;
states st;
int ch;
FILE *d;
{
	register struct re_guts *g = m->g;
	register int i;
	register int first = 1;

	if (!(m->eflags&REG_TRACE))
		return;

	fprintf(d, "%s", caption);
	if (ch != '\0')
		fprintf(d, " %s", pchar(ch));
	for (i = 0; i < g->nstates; i++)
		if (ISSET(st, i)) {
			fprintf(d, "%s%d", (first) ? "\t" : ", ", i);
			first = 0;
		}
	fprintf(d, "\n");
}

/* 
 - at - print current situation
 == #ifdef REDEBUG
 == static void at(struct match *m, char *title, char *start, char *stop, \
 ==						sopno startst, sopno stopst);
 == #endif
 */
static void
at(m, title, start, stop, startst, stopst)
struct match *m;
char *title;
char *start;
char *stop;
sopno startst;
sopno stopst;
{
	if (!(m->eflags&REG_TRACE))
		return;

	printf("%s %s-", title, pchar(*start));
	printf("%s ", pchar(*stop));
	printf("%ld-%ld\n", (long)startst, (long)stopst);
}

#ifndef PCHARDONE
#define	PCHARDONE	/* never again */
/*
 - pchar - make a character printable
 == #ifdef REDEBUG
 == static char *pchar(int ch);
 == #endif
 *
 * Is this identical to regchar() over in debug.c?  Well, yes.  But a
 * duplicate here avoids having a debugging-capable regexec.o tied to
 * a matching debug.o, and this is convenient.  It all disappears in
 * the non-debug compilation anyway, so it doesn't matter much.
 */
static char *			/* -> representation */
pchar(ch)
int ch;
{
	static char pbuf[10];

	if (isprint(ch) || ch == ' ')
		sprintf(pbuf, "%c", ch);
	else
		sprintf(pbuf, "\\%o", ch);
	return(pbuf);
}
#endif
#endif

#undef	matcher
#undef	fast
#undef	slow
#undef	dissect
#undef	backref
#undef	step
#undef	print
#undef	at
#undef	match