[wxWidgets.git] / src / regex / rege_dfa.c

/*
 * DFA routines
 * This file is #included by regexec.c.
 *
 * Copyright (c) 1998, 1999 Henry Spencer.	All rights reserved.
 *
 * Development of this software was funded, in part, by Cray Research Inc.,
 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
 * Corporation, none of whom are responsible for the results.  The author
 * thanks all of them.
 *
 * Redistribution and use in source and binary forms -- with or without
 * modification -- are permitted for any purpose, provided that
 * redistributions in source form retain this entire copyright notice and
 * indicate the origin and nature of any modifications.
 *
 * I'd appreciate being given credit for this package in the documentation
 * of software which uses it, but that is not a requirement.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $Header$
 *
 */

/*
 * longest - longest-preferred matching engine
 */
static chr *					/* endpoint, or NULL */
longest(struct vars * v,		/* used only for debug and exec flags */
		struct dfa * d,
		chr *start,				/* where the match should start */
		chr *stop,				/* match must end at or before here */
		int *hitstopp)			/* record whether hit v->stop, if non-NULL */
{
	chr		   *cp;
	chr		   *realstop = (stop == v->stop) ? stop : stop + 1;
	color		co;
	struct sset *css;
	struct sset *ss;
	chr		   *post;
	int			i;
	struct colormap *cm = d->cm;

	/* initialize */
	css = initialize(v, d, start);
	cp = start;
	if (hitstopp != NULL)
		*hitstopp = 0;

	/* startup */
	FDEBUG(("+++ startup +++\n"));
	if (cp == v->start)
	{
		co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
		FDEBUG(("color %ld\n", (long) co));
	}
	else
	{
		co = GETCOLOR(cm, *(cp - 1));
		FDEBUG(("char %c, color %ld\n", (char) *(cp - 1), (long) co));
	}
	css = miss(v, d, css, co, cp, start);
	if (css == NULL)
		return NULL;
	css->lastseen = cp;

	/* main loop */
	if (v->eflags & REG_FTRACE)
		while (cp < realstop)
		{
			FDEBUG(("+++ at c%d +++\n", css - d->ssets));
			co = GETCOLOR(cm, *cp);
			FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
			ss = css->outs[co];
			if (ss == NULL)
			{
				ss = miss(v, d, css, co, cp + 1, start);
				if (ss == NULL)
					break;		/* NOTE BREAK OUT */
			}
			cp++;
			ss->lastseen = cp;
			css = ss;
		}
	else
		while (cp < realstop)
		{
			co = GETCOLOR(cm, *cp);
			ss = css->outs[co];
			if (ss == NULL)
			{
				ss = miss(v, d, css, co, cp + 1, start);
				if (ss == NULL)
					break;		/* NOTE BREAK OUT */
			}
			cp++;
			ss->lastseen = cp;
			css = ss;
		}

	/* shutdown */
	FDEBUG(("+++ shutdown at c%d +++\n", css - d->ssets));
	if (cp == v->stop && stop == v->stop)
	{
		if (hitstopp != NULL)
			*hitstopp = 1;
		co = d->cnfa->eos[(v->eflags & REG_NOTEOL) ? 0 : 1];
		FDEBUG(("color %ld\n", (long) co));
		ss = miss(v, d, css, co, cp, start);
		/* special case:  match ended at eol? */
		if (ss != NULL && (ss->flags & POSTSTATE))
			return cp;
		else if (ss != NULL)
			ss->lastseen = cp;	/* to be tidy */
	}

	/* find last match, if any */
	post = d->lastpost;
	for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
		if ((ss->flags & POSTSTATE) && post != ss->lastseen &&
			(post == NULL || post < ss->lastseen))
			post = ss->lastseen;
	if (post != NULL)			/* found one */
		return post - 1;

	return NULL;
}

/*
 * shortest - shortest-preferred matching engine
 */
static chr *					/* endpoint, or NULL */
shortest(struct vars * v,
		 struct dfa * d,
		 chr *start,			/* where the match should start */
		 chr *min,				/* match must end at or after here */
		 chr *max,				/* match must end at or before here */
		 chr **coldp,			/* store coldstart pointer here, if
								 * nonNULL */
		 int *hitstopp)			/* record whether hit v->stop, if non-NULL */
{
	chr		   *cp;
	chr		   *realmin = (min == v->stop) ? min : min + 1;
	chr		   *realmax = (max == v->stop) ? max : max + 1;
	color		co;
	struct sset *css;
	struct sset *ss;
	struct colormap *cm = d->cm;

	/* initialize */
	css = initialize(v, d, start);
	cp = start;
	if (hitstopp != NULL)
		*hitstopp = 0;

	/* startup */
	FDEBUG(("--- startup ---\n"));
	if (cp == v->start)
	{
		co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
		FDEBUG(("color %ld\n", (long) co));
	}
	else
	{
		co = GETCOLOR(cm, *(cp - 1));
		FDEBUG(("char %c, color %ld\n", (char) *(cp - 1), (long) co));
	}
	css = miss(v, d, css, co, cp, start);
	if (css == NULL)
		return NULL;
	css->lastseen = cp;
	ss = css;

	/* main loop */
	if (v->eflags & REG_FTRACE)
		while (cp < realmax)
		{
			FDEBUG(("--- at c%d ---\n", css - d->ssets));
			co = GETCOLOR(cm, *cp);
			FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
			ss = css->outs[co];
			if (ss == NULL)
			{
				ss = miss(v, d, css, co, cp + 1, start);
				if (ss == NULL)
					break;		/* NOTE BREAK OUT */
			}
			cp++;
			ss->lastseen = cp;
			css = ss;
			if ((ss->flags & POSTSTATE) && cp >= realmin)
				break;			/* NOTE BREAK OUT */
		}
	else
		while (cp < realmax)
		{
			co = GETCOLOR(cm, *cp);
			ss = css->outs[co];
			if (ss == NULL)
			{
				ss = miss(v, d, css, co, cp + 1, start);
				if (ss == NULL)
					break;		/* NOTE BREAK OUT */
			}
			cp++;
			ss->lastseen = cp;
			css = ss;
			if ((ss->flags & POSTSTATE) && cp >= realmin)
				break;			/* NOTE BREAK OUT */
		}

	if (ss == NULL)
		return NULL;

	if (coldp != NULL)			/* report last no-progress state set, if
								 * any */
		*coldp = lastcold(v, d);

	if ((ss->flags & POSTSTATE) && cp > min)
	{
		assert(cp >= realmin);
		cp--;
	}
	else if (cp == v->stop && max == v->stop)
	{
		co = d->cnfa->eos[(v->eflags & REG_NOTEOL) ? 0 : 1];
		FDEBUG(("color %ld\n", (long) co));
		ss = miss(v, d, css, co, cp, start);
		/* match might have ended at eol */
		if ((ss == NULL || !(ss->flags & POSTSTATE)) && hitstopp != NULL)
			*hitstopp = 1;
	}

	if (ss == NULL || !(ss->flags & POSTSTATE))
		return NULL;

	return cp;
}

/*
 * lastcold - determine last point at which no progress had been made
 */
static chr *					/* endpoint, or NULL */
lastcold(struct vars * v,
		 struct dfa * d)
{
	struct sset *ss;
	chr		   *nopr;
	int			i;

	nopr = d->lastnopr;
	if (nopr == NULL)
		nopr = v->start;
	for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
		if ((ss->flags & NOPROGRESS) && nopr < ss->lastseen)
			nopr = ss->lastseen;
	return nopr;
}

/*
 * newdfa - set up a fresh DFA
 */
static struct dfa *
newdfa(struct vars * v,
	   struct cnfa * cnfa,
	   struct colormap * cm,
	   struct smalldfa * small) /* preallocated space, may be NULL */
{
	struct dfa *d;
	size_t		nss = cnfa->nstates * 2;
	int			wordsper = (cnfa->nstates + UBITS - 1) / UBITS;
	struct smalldfa *smallwas = small;

	assert(cnfa != NULL && cnfa->nstates != 0);

	if (nss <= FEWSTATES && cnfa->ncolors <= FEWCOLORS)
	{
		assert(wordsper == 1);
		if (small == NULL)
		{
			small = (struct smalldfa *) MALLOC(
											   sizeof(struct smalldfa));
			if (small == NULL)
			{
				ERR(REG_ESPACE);
				return NULL;
			}
		}
		d = &small->dfa;
		d->ssets = small->ssets;
		d->statesarea = small->statesarea;
		d->work = &d->statesarea[nss];
		d->outsarea = small->outsarea;
		d->incarea = small->incarea;
		d->cptsmalloced = 0;
		d->mallocarea = (smallwas == NULL) ? (char *) small : NULL;
	}
	else
	{
		d = (struct dfa *) MALLOC(sizeof(struct dfa));
		if (d == NULL)
		{
			ERR(REG_ESPACE);
			return NULL;
		}
		d->ssets = (struct sset *) MALLOC(nss * sizeof(struct sset));
		d->statesarea = (unsigned *) MALLOC((nss + WORK) * wordsper *
											sizeof(unsigned));
		d->work = &d->statesarea[nss * wordsper];
		d->outsarea = (struct sset **) MALLOC(nss * cnfa->ncolors *
											  sizeof(struct sset *));
		d->incarea = (struct arcp *) MALLOC(nss * cnfa->ncolors *
											sizeof(struct arcp));
		d->cptsmalloced = 1;
		d->mallocarea = (char *) d;
		if (d->ssets == NULL || d->statesarea == NULL ||
			d->outsarea == NULL || d->incarea == NULL)
		{
			freedfa(d);
			ERR(REG_ESPACE);
			return NULL;
		}
	}

	d->nssets = (v->eflags & REG_SMALL) ? 7 : nss;
	d->nssused = 0;
	d->nstates = cnfa->nstates;
	d->ncolors = cnfa->ncolors;
	d->wordsper = wordsper;
	d->cnfa = cnfa;
	d->cm = cm;
	d->lastpost = NULL;
	d->lastnopr = NULL;
	d->search = d->ssets;

	/* initialization of sset fields is done as needed */

	return d;
}

/*
 * freedfa - free a DFA
 */
static void
freedfa(struct dfa * d)
{
	if (d->cptsmalloced)
	{
		if (d->ssets != NULL)
			FREE(d->ssets);
		if (d->statesarea != NULL)
			FREE(d->statesarea);
		if (d->outsarea != NULL)
			FREE(d->outsarea);
		if (d->incarea != NULL)
			FREE(d->incarea);
	}

	if (d->mallocarea != NULL)
		FREE(d->mallocarea);
}

/*
 * hash - construct a hash code for a bitvector
 *
 * There are probably better ways, but they're more expensive.
 */
static unsigned
hash(unsigned *uv,
	 int n)
{
	int			i;
	unsigned	h;

	h = 0;
	for (i = 0; i < n; i++)
		h ^= uv[i];
	return h;
}

/*
 * initialize - hand-craft a cache entry for startup, otherwise get ready
 */
static struct sset *
initialize(struct vars * v,		/* used only for debug flags */
		   struct dfa * d,
		   chr *start)
{
	struct sset *ss;
	int			i;

	/* is previous one still there? */
	if (d->nssused > 0 && (d->ssets[0].flags & STARTER))
		ss = &d->ssets[0];
	else
	{							/* no, must (re)build it */
		ss = getvacant(v, d, start, start);
		for (i = 0; i < d->wordsper; i++)
			ss->states[i] = 0;
		BSET(ss->states, d->cnfa->pre);
		ss->hash = HASH(ss->states, d->wordsper);
		assert(d->cnfa->pre != d->cnfa->post);
		ss->flags = STARTER | LOCKED | NOPROGRESS;
		/* lastseen dealt with below */
	}

	for (i = 0; i < d->nssused; i++)
		d->ssets[i].lastseen = NULL;
	ss->lastseen = start;		/* maybe untrue, but harmless */
	d->lastpost = NULL;
	d->lastnopr = NULL;
	return ss;
}

/*
 * miss - handle a cache miss
 */
static struct sset *			/* NULL if goes to empty set */
miss(struct vars * v,			/* used only for debug flags */
	 struct dfa * d,
	 struct sset * css,
	 pcolor co,
	 chr *cp,					/* next chr */
	 chr *start)				/* where the attempt got started */
{
	struct cnfa *cnfa = d->cnfa;
	int			i;
	unsigned	h;
	struct carc *ca;
	struct sset *p;
	int			ispost;
	int			noprogress;
	int			gotstate;
	int			dolacons;
	int			sawlacons;

	/* for convenience, we can be called even if it might not be a miss */
	if (css->outs[co] != NULL)
	{
		FDEBUG(("hit\n"));
		return css->outs[co];
	}
	FDEBUG(("miss\n"));

	/* first, what set of states would we end up in? */
	for (i = 0; i < d->wordsper; i++)
		d->work[i] = 0;
	ispost = 0;
	noprogress = 1;
	gotstate = 0;
	for (i = 0; i < d->nstates; i++)
		if (ISBSET(css->states, i))
			for (ca = cnfa->states[i] + 1; ca->co != COLORLESS; ca++)
				if (ca->co == co)
				{
					BSET(d->work, ca->to);
					gotstate = 1;
					if (ca->to == cnfa->post)
						ispost = 1;
					if (!cnfa->states[ca->to]->co)
						noprogress = 0;
					FDEBUG(("%d -> %d\n", i, ca->to));
				}
	dolacons = (gotstate) ? (cnfa->flags & HASLACONS) : 0;
	sawlacons = 0;
	while (dolacons)
	{							/* transitive closure */
		dolacons = 0;
		for (i = 0; i < d->nstates; i++)
			if (ISBSET(d->work, i))
				for (ca = cnfa->states[i] + 1; ca->co != COLORLESS;
					 ca++)
				{
					if (ca->co <= cnfa->ncolors)
						continue;		/* NOTE CONTINUE */
					sawlacons = 1;
					if (ISBSET(d->work, ca->to))
						continue;		/* NOTE CONTINUE */
					if (!lacon(v, cnfa, cp, ca->co))
						continue;		/* NOTE CONTINUE */
					BSET(d->work, ca->to);
					dolacons = 1;
					if (ca->to == cnfa->post)
						ispost = 1;
					if (!cnfa->states[ca->to]->co)
						noprogress = 0;
					FDEBUG(("%d :> %d\n", i, ca->to));
				}
	}
	if (!gotstate)
		return NULL;
	h = HASH(d->work, d->wordsper);

	/* next, is that in the cache? */
	for (p = d->ssets, i = d->nssused; i > 0; p++, i--)
		if (HIT(h, d->work, p, d->wordsper))
		{
			FDEBUG(("cached c%d\n", p - d->ssets));
			break;				/* NOTE BREAK OUT */
		}
	if (i == 0)
	{							/* nope, need a new cache entry */
		p = getvacant(v, d, cp, start);
		assert(p != css);
		for (i = 0; i < d->wordsper; i++)
			p->states[i] = d->work[i];
		p->hash = h;
		p->flags = (ispost) ? POSTSTATE : 0;
		if (noprogress)
			p->flags |= NOPROGRESS;
		/* lastseen to be dealt with by caller */
	}

	if (!sawlacons)
	{							/* lookahead conds. always cache miss */
		FDEBUG(("c%d[%d]->c%d\n", css - d->ssets, co, p - d->ssets));
		css->outs[co] = p;
		css->inchain[co] = p->ins;
		p->ins.ss = css;
		p->ins.co = (color) co;
	}
	return p;
}

/*
 * lacon - lookahead-constraint checker for miss()
 */
static int						/* predicate:  constraint satisfied? */
lacon(struct vars * v,
	  struct cnfa * pcnfa,		/* parent cnfa */
	  chr *cp,
	  pcolor co)				/* "color" of the lookahead constraint */
{
	int			n;
	struct subre *sub;
	struct dfa *d;
	struct smalldfa sd;
	chr		   *end;

	n = co - pcnfa->ncolors;
	assert(n < v->g->nlacons && v->g->lacons != NULL);
	FDEBUG(("=== testing lacon %d\n", n));
	sub = &v->g->lacons[n];
	d = newdfa(v, &sub->cnfa, &v->g->cmap, &sd);
	if (d == NULL)
	{
		ERR(REG_ESPACE);
		return 0;
	}
	end = longest(v, d, cp, v->stop, (int *) NULL);
	freedfa(d);
	FDEBUG(("=== lacon %d match %d\n", n, (end != NULL)));
	return (sub->subno) ? (end != NULL) : (end == NULL);
}

/*
 * getvacant - get a vacant state set
 * This routine clears out the inarcs and outarcs, but does not otherwise
 * clear the innards of the state set -- that's up to the caller.
 */
static struct sset *
getvacant(struct vars * v,		/* used only for debug flags */
		  struct dfa * d,
		  chr *cp,
		  chr *start)
{
	int			i;
	struct sset *ss;
	struct sset *p;
	struct arcp ap;
	struct arcp lastap;
	color		co;

	ss = pickss(v, d, cp, start);
	assert(!(ss->flags & LOCKED));

	/* clear out its inarcs, including self-referential ones */
	ap = ss->ins;
	while ((p = ap.ss) != NULL)
	{
		co = ap.co;
		FDEBUG(("zapping c%d's %ld outarc\n", p - d->ssets, (long) co));
		p->outs[co] = NULL;
		ap = p->inchain[co];
		p->inchain[co].ss = NULL;		/* paranoia */
	}
	ss->ins.ss = NULL;

	/* take it off the inarc chains of the ssets reached by its outarcs */
	for (i = 0; i < d->ncolors; i++)
	{
		p = ss->outs[i];
		assert(p != ss);		/* not self-referential */
		if (p == NULL)
			continue;			/* NOTE CONTINUE */
		FDEBUG(("del outarc %d from c%d's in chn\n", i, p - d->ssets));
		if (p->ins.ss == ss && p->ins.co == i)
			p->ins = ss->inchain[i];
		else
		{
			assert(p->ins.ss != NULL);
			for (ap = p->ins; ap.ss != NULL &&
				 !(ap.ss == ss && ap.co == i);
				 ap = ap.ss->inchain[ap.co])
				lastap = ap;
			assert(ap.ss != NULL);
			lastap.ss->inchain[lastap.co] = ss->inchain[i];
		}
		ss->outs[i] = NULL;
		ss->inchain[i].ss = NULL;
	}

	/* if ss was a success state, may need to remember location */
	if ((ss->flags & POSTSTATE) && ss->lastseen != d->lastpost &&
		(d->lastpost == NULL || d->lastpost < ss->lastseen))
		d->lastpost = ss->lastseen;

	/* likewise for a no-progress state */
	if ((ss->flags & NOPROGRESS) && ss->lastseen != d->lastnopr &&
		(d->lastnopr == NULL || d->lastnopr < ss->lastseen))
		d->lastnopr = ss->lastseen;

	return ss;
}

/*
 * pickss - pick the next stateset to be used
 */
static struct sset *
pickss(struct vars * v,			/* used only for debug flags */
	   struct dfa * d,
	   chr *cp,
	   chr *start)
{
	int			i;
	struct sset *ss;
	struct sset *end;
	chr		   *ancient;

	/* shortcut for cases where cache isn't full */
	if (d->nssused < d->nssets)
	{
		i = d->nssused;
		d->nssused++;
		ss = &d->ssets[i];
		FDEBUG(("new c%d\n", i));
		/* set up innards */
		ss->states = &d->statesarea[i * d->wordsper];
		ss->flags = 0;
		ss->ins.ss = NULL;
		ss->ins.co = WHITE;		/* give it some value */
		ss->outs = &d->outsarea[i * d->ncolors];
		ss->inchain = &d->incarea[i * d->ncolors];
		for (i = 0; i < d->ncolors; i++)
		{
			ss->outs[i] = NULL;
			ss->inchain[i].ss = NULL;
		}
		return ss;
	}

	/* look for oldest, or old enough anyway */
	if (cp - start > d->nssets * 2 / 3) /* oldest 33% are expendable */
		ancient = cp - d->nssets * 2 / 3;
	else
		ancient = start;
	for (ss = d->search, end = &d->ssets[d->nssets]; ss < end; ss++)
		if ((ss->lastseen == NULL || ss->lastseen < ancient) &&
			!(ss->flags & LOCKED))
		{
			d->search = ss + 1;
			FDEBUG(("replacing c%d\n", ss - d->ssets));
			return ss;
		}
	for (ss = d->ssets, end = d->search; ss < end; ss++)
		if ((ss->lastseen == NULL || ss->lastseen < ancient) &&
			!(ss->flags & LOCKED))
		{
			d->search = ss + 1;
			FDEBUG(("replacing c%d\n", ss - d->ssets));
			return ss;
		}

	/* nobody's old enough?!? -- something's really wrong */
	FDEBUG(("can't find victim to replace!\n"));
	assert(NOTREACHED);
	ERR(REG_ASSERT);
	return d->ssets;
}
Commit	Line	Data
48bf5def RN	1	/*
	2	* DFA routines
	3	* This file is #included by regexec.c.
	4	*
	5	* Copyright (c) 1998, 1999 Henry Spencer. All rights reserved.
	6	*
	7	* Development of this software was funded, in part, by Cray Research Inc.,
	8	* UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
	9	* Corporation, none of whom are responsible for the results. The author
	10	* thanks all of them.
	11	*
	12	* Redistribution and use in source and binary forms -- with or without
	13	* modification -- are permitted for any purpose, provided that
	14	* redistributions in source form retain this entire copyright notice and
	15	* indicate the origin and nature of any modifications.
	16	*
	17	* I'd appreciate being given credit for this package in the documentation
	18	* of software which uses it, but that is not a requirement.
	19	*
	20	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
	21	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
	22	* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
	23	* HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	24	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	25	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
	26	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
	27	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
	28	* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	29	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	30	*
	31	* $Header$
	32	*
	33	*/
	34
	35	/*
	36	* longest - longest-preferred matching engine
	37	*/
	38	static chr * /* endpoint, or NULL */
	39	longest(struct vars * v, /* used only for debug and exec flags */
	40	struct dfa * d,
	41	chr start, / where the match should start */
	42	chr stop, / match must end at or before here */
	43	int hitstopp) / record whether hit v->stop, if non-NULL */
	44	{
	45	chr *cp;
	46	chr *realstop = (stop == v->stop) ? stop : stop + 1;
	47	color co;
	48	struct sset *css;
	49	struct sset *ss;
	50	chr *post;
	51	int i;
	52	struct colormap *cm = d->cm;
	53
	54	/* initialize */
	55	css = initialize(v, d, start);
	56	cp = start;
	57	if (hitstopp != NULL)
	58	*hitstopp = 0;
	59
	60	/* startup */
	61	FDEBUG(("+++ startup +++\n"));
	62	if (cp == v->start)
	63	{
	64	co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
65	FDEBUG(("color %ld\n", (long) co));
66	}
67	else
68	{
69	co = GETCOLOR(cm, *(cp - 1));
70	FDEBUG(("char %c, color %ld\n", (char) *(cp - 1), (long) co));
71	}
72	css = miss(v, d, css, co, cp, start);
73	if (css == NULL)
74	return NULL;
75	css->lastseen = cp;
76
77	/* main loop */
78	if (v->eflags & REG_FTRACE)
79	while (cp < realstop)
80	{
81	FDEBUG(("+++ at c%d +++\n", css - d->ssets));
82	co = GETCOLOR(cm, *cp);
83	FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
84	ss = css->outs[co];
85	if (ss == NULL)
86	{
87	ss = miss(v, d, css, co, cp + 1, start);
88	if (ss == NULL)
89	break; /* NOTE BREAK OUT */
90	}
91	cp++;
92	ss->lastseen = cp;
93	css = ss;
94	}
95	else
96	while (cp < realstop)
97	{
98	co = GETCOLOR(cm, *cp);
99	ss = css->outs[co];
100	if (ss == NULL)
101	{
102	ss = miss(v, d, css, co, cp + 1, start);
103	if (ss == NULL)
104	break; /* NOTE BREAK OUT */
105	}
106	cp++;
107	ss->lastseen = cp;
108	css = ss;
109	}
110
111	/* shutdown */
112	FDEBUG(("+++ shutdown at c%d +++\n", css - d->ssets));
113	if (cp == v->stop && stop == v->stop)
114	{
115	if (hitstopp != NULL)
116	*hitstopp = 1;
117	co = d->cnfa->eos[(v->eflags & REG_NOTEOL) ? 0 : 1];
118	FDEBUG(("color %ld\n", (long) co));
119	ss = miss(v, d, css, co, cp, start);
120	/* special case: match ended at eol? */
121	if (ss != NULL && (ss->flags & POSTSTATE))
122	return cp;
123	else if (ss != NULL)
124	ss->lastseen = cp; /* to be tidy */
125	}
126
127	/* find last match, if any */
128	post = d->lastpost;
129	for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
130	if ((ss->flags & POSTSTATE) && post != ss->lastseen &&
131	(post == NULL \|\| post < ss->lastseen))
132	post = ss->lastseen;
133	if (post != NULL) /* found one */
134	return post - 1;
135
136	return NULL;
137	}
138
139	/*
140	* shortest - shortest-preferred matching engine
141	*/
142	static chr * /* endpoint, or NULL */
143	shortest(struct vars * v,
144	struct dfa * d,
145	chr start, / where the match should start */
146	chr min, / match must end at or after here */
147	chr max, / match must end at or before here */
148	chr *coldp, / store coldstart pointer here, if
149	* nonNULL */
150	int hitstopp) / record whether hit v->stop, if non-NULL */
151	{
152	chr *cp;
153	chr *realmin = (min == v->stop) ? min : min + 1;
154	chr *realmax = (max == v->stop) ? max : max + 1;
155	color co;
156	struct sset *css;
157	struct sset *ss;
158	struct colormap *cm = d->cm;
159
160	/* initialize */
161	css = initialize(v, d, start);
162	cp = start;
163	if (hitstopp != NULL)
164	*hitstopp = 0;
165
166	/* startup */
167	FDEBUG(("--- startup ---\n"));
168	if (cp == v->start)
169	{
170	co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
171	FDEBUG(("color %ld\n", (long) co));
172	}
173	else
174	{
175	co = GETCOLOR(cm, *(cp - 1));
176	FDEBUG(("char %c, color %ld\n", (char) *(cp - 1), (long) co));
177	}
178	css = miss(v, d, css, co, cp, start);
179	if (css == NULL)
180	return NULL;
181	css->lastseen = cp;
182	ss = css;
183
184	/* main loop */
185	if (v->eflags & REG_FTRACE)
186	while (cp < realmax)
187	{
188	FDEBUG(("--- at c%d ---\n", css - d->ssets));
189	co = GETCOLOR(cm, *cp);
190	FDEBUG(("char %c, color %ld\n", (char) *cp, (long) co));
191	ss = css->outs[co];
192	if (ss == NULL)
193	{
194	ss = miss(v, d, css, co, cp + 1, start);
195	if (ss == NULL)
196	break; /* NOTE BREAK OUT */
197	}
198	cp++;
199	ss->lastseen = cp;
200	css = ss;
201	if ((ss->flags & POSTSTATE) && cp >= realmin)
202	break; /* NOTE BREAK OUT */
203	}
204	else
205	while (cp < realmax)
206	{
207	co = GETCOLOR(cm, *cp);
208	ss = css->outs[co];
209	if (ss == NULL)
210	{
211	ss = miss(v, d, css, co, cp + 1, start);
212	if (ss == NULL)
213	break; /* NOTE BREAK OUT */
214	}
215	cp++;
216	ss->lastseen = cp;
217	css = ss;
218	if ((ss->flags & POSTSTATE) && cp >= realmin)
219	break; /* NOTE BREAK OUT */
220	}
221
222	if (ss == NULL)
223	return NULL;
224
225	if (coldp != NULL) /* report last no-progress state set, if
226	* any */
227	*coldp = lastcold(v, d);
228
229	if ((ss->flags & POSTSTATE) && cp > min)
230	{
231	assert(cp >= realmin);
232	cp--;
233	}
234	else if (cp == v->stop && max == v->stop)
235	{
236	co = d->cnfa->eos[(v->eflags & REG_NOTEOL) ? 0 : 1];
237	FDEBUG(("color %ld\n", (long) co));
238	ss = miss(v, d, css, co, cp, start);
239	/* match might have ended at eol */
240	if ((ss == NULL \|\| !(ss->flags & POSTSTATE)) && hitstopp != NULL)
241	*hitstopp = 1;
242	}
243
244	if (ss == NULL \|\| !(ss->flags & POSTSTATE))
245	return NULL;
246
247	return cp;
248	}
249
250	/*
251	* lastcold - determine last point at which no progress had been made
252	*/
253	static chr * /* endpoint, or NULL */
254	lastcold(struct vars * v,
255	struct dfa * d)
256	{
257	struct sset *ss;
258	chr *nopr;
259	int i;
260
261	nopr = d->lastnopr;
262	if (nopr == NULL)
263	nopr = v->start;
264	for (ss = d->ssets, i = d->nssused; i > 0; ss++, i--)
265	if ((ss->flags & NOPROGRESS) && nopr < ss->lastseen)
266	nopr = ss->lastseen;
267	return nopr;
268	}
269
270	/*
271	* newdfa - set up a fresh DFA
272	*/
273	static struct dfa *
274	newdfa(struct vars * v,
275	struct cnfa * cnfa,
276	struct colormap * cm,
277	struct smalldfa * small) /* preallocated space, may be NULL */
278	{
279	struct dfa *d;
280	size_t nss = cnfa->nstates * 2;
281	int wordsper = (cnfa->nstates + UBITS - 1) / UBITS;
282	struct smalldfa *smallwas = small;
283
284	assert(cnfa != NULL && cnfa->nstates != 0);
285
286	if (nss <= FEWSTATES && cnfa->ncolors <= FEWCOLORS)
287	{
288	assert(wordsper == 1);
289	if (small == NULL)
290	{
291	small = (struct smalldfa *) MALLOC(
292	sizeof(struct smalldfa));
293	if (small == NULL)
294	{
295	ERR(REG_ESPACE);
296	return NULL;
297	}
298	}
299	d = &small->dfa;
300	d->ssets = small->ssets;
301	d->statesarea = small->statesarea;
302	d->work = &d->statesarea[nss];
303	d->outsarea = small->outsarea;
304	d->incarea = small->incarea;
305	d->cptsmalloced = 0;
306	d->mallocarea = (smallwas == NULL) ? (char *) small : NULL;
307	}
308	else
309	{
310	d = (struct dfa *) MALLOC(sizeof(struct dfa));
311	if (d == NULL)
312	{
313	ERR(REG_ESPACE);
314	return NULL;
315	}
316	d->ssets = (struct sset ) MALLOC(nss sizeof(struct sset));
317	d->statesarea = (unsigned ) MALLOC((nss + WORK) wordsper *
318	sizeof(unsigned));
319	d->work = &d->statesarea[nss * wordsper];
320	d->outsarea = (struct sset *) MALLOC(nss cnfa->ncolors *
321	sizeof(struct sset *));
322	d->incarea = (struct arcp ) MALLOC(nss cnfa->ncolors *
323	sizeof(struct arcp));
324	d->cptsmalloced = 1;
325	d->mallocarea = (char *) d;
326	if (d->ssets == NULL \|\| d->statesarea == NULL \|\|
327	d->outsarea == NULL \|\| d->incarea == NULL)
328	{
329	freedfa(d);
330	ERR(REG_ESPACE);
331	return NULL;
332	}
333	}
334
335	d->nssets = (v->eflags & REG_SMALL) ? 7 : nss;
336	d->nssused = 0;
337	d->nstates = cnfa->nstates;
338	d->ncolors = cnfa->ncolors;
339	d->wordsper = wordsper;
340	d->cnfa = cnfa;
341	d->cm = cm;
342	d->lastpost = NULL;
343	d->lastnopr = NULL;
344	d->search = d->ssets;
345
346	/* initialization of sset fields is done as needed */
347
348	return d;
349	}
350
351	/*
352	* freedfa - free a DFA
353	*/
354	static void
355	freedfa(struct dfa * d)
356	{
357	if (d->cptsmalloced)
358	{
359	if (d->ssets != NULL)
360	FREE(d->ssets);
361	if (d->statesarea != NULL)
362	FREE(d->statesarea);
363	if (d->outsarea != NULL)
364	FREE(d->outsarea);
365	if (d->incarea != NULL)
366	FREE(d->incarea);
367	}
368
369	if (d->mallocarea != NULL)
370	FREE(d->mallocarea);
371	}
372
373	/*
374	* hash - construct a hash code for a bitvector
375	*
376	* There are probably better ways, but they're more expensive.
377	*/
378	static unsigned
379	hash(unsigned *uv,
380	int n)
381	{
382	int i;
383	unsigned h;
384
385	h = 0;
386	for (i = 0; i < n; i++)
387	h ^= uv[i];
388	return h;
389	}
390
391	/*
392	* initialize - hand-craft a cache entry for startup, otherwise get ready
393	*/
394	static struct sset *
395	initialize(struct vars * v, /* used only for debug flags */
396	struct dfa * d,
397	chr *start)
398	{
399	struct sset *ss;
400	int i;
401
402	/* is previous one still there? */
403	if (d->nssused > 0 && (d->ssets[0].flags & STARTER))
404	ss = &d->ssets[0];
405	else
406	{ /* no, must (re)build it */
407	ss = getvacant(v, d, start, start);
408	for (i = 0; i < d->wordsper; i++)
409	ss->states[i] = 0;
410	BSET(ss->states, d->cnfa->pre);
411	ss->hash = HASH(ss->states, d->wordsper);
412	assert(d->cnfa->pre != d->cnfa->post);
413	ss->flags = STARTER \| LOCKED \| NOPROGRESS;
414	/* lastseen dealt with below */
415	}
416
417	for (i = 0; i < d->nssused; i++)
418	d->ssets[i].lastseen = NULL;
419	ss->lastseen = start; /* maybe untrue, but harmless */
420	d->lastpost = NULL;
421	d->lastnopr = NULL;
422	return ss;
423	}
424
425	/*
426	* miss - handle a cache miss
427	*/
428	static struct sset * /* NULL if goes to empty set */
429	miss(struct vars * v, /* used only for debug flags */
430	struct dfa * d,
431	struct sset * css,
432	pcolor co,
433	chr cp, / next chr */
434	chr start) / where the attempt got started */
435	{
436	struct cnfa *cnfa = d->cnfa;
437	int i;
438	unsigned h;
439	struct carc *ca;
440	struct sset *p;
441	int ispost;
442	int noprogress;
443	int gotstate;
444	int dolacons;
445	int sawlacons;
446
447	/* for convenience, we can be called even if it might not be a miss */
448	if (css->outs[co] != NULL)
449	{
450	FDEBUG(("hit\n"));
451	return css->outs[co];
452	}
453	FDEBUG(("miss\n"));
454
455	/* first, what set of states would we end up in? */
456	for (i = 0; i < d->wordsper; i++)
457	d->work[i] = 0;
458	ispost = 0;
459	noprogress = 1;
460	gotstate = 0;
461	for (i = 0; i < d->nstates; i++)
462	if (ISBSET(css->states, i))
463	for (ca = cnfa->states[i] + 1; ca->co != COLORLESS; ca++)
464	if (ca->co == co)
465	{
466	BSET(d->work, ca->to);
467	gotstate = 1;
468	if (ca->to == cnfa->post)
469	ispost = 1;
470	if (!cnfa->states[ca->to]->co)
471	noprogress = 0;
472	FDEBUG(("%d -> %d\n", i, ca->to));
473	}
474	dolacons = (gotstate) ? (cnfa->flags & HASLACONS) : 0;
475	sawlacons = 0;
476	while (dolacons)
477	{ /* transitive closure */
478	dolacons = 0;
479	for (i = 0; i < d->nstates; i++)
480	if (ISBSET(d->work, i))
481	for (ca = cnfa->states[i] + 1; ca->co != COLORLESS;
482	ca++)
483	{
484	if (ca->co <= cnfa->ncolors)
485	continue; /* NOTE CONTINUE */
486	sawlacons = 1;
487	if (ISBSET(d->work, ca->to))
488	continue; /* NOTE CONTINUE */
489	if (!lacon(v, cnfa, cp, ca->co))
490	continue; /* NOTE CONTINUE */
491	BSET(d->work, ca->to);
492	dolacons = 1;
493	if (ca->to == cnfa->post)
494	ispost = 1;
495	if (!cnfa->states[ca->to]->co)
496	noprogress = 0;
497	FDEBUG(("%d :> %d\n", i, ca->to));
498	}
499	}
500	if (!gotstate)
501	return NULL;
502	h = HASH(d->work, d->wordsper);
503
504	/* next, is that in the cache? */
505	for (p = d->ssets, i = d->nssused; i > 0; p++, i--)
506	if (HIT(h, d->work, p, d->wordsper))
507	{
508	FDEBUG(("cached c%d\n", p - d->ssets));
509	break; /* NOTE BREAK OUT */
510	}
511	if (i == 0)
512	{ /* nope, need a new cache entry */
513	p = getvacant(v, d, cp, start);
514	assert(p != css);
515	for (i = 0; i < d->wordsper; i++)
516	p->states[i] = d->work[i];
517	p->hash = h;
518	p->flags = (ispost) ? POSTSTATE : 0;
519	if (noprogress)
520	p->flags \|= NOPROGRESS;
521	/* lastseen to be dealt with by caller */
522	}
523
524	if (!sawlacons)
525	{ /* lookahead conds. always cache miss */
526	FDEBUG(("c%d[%d]->c%d\n", css - d->ssets, co, p - d->ssets));
527	css->outs[co] = p;
528	css->inchain[co] = p->ins;
529	p->ins.ss = css;
530	p->ins.co = (color) co;
531	}
532	return p;
533	}
534
535	/*
536	* lacon - lookahead-constraint checker for miss()
537	*/
538	static int /* predicate: constraint satisfied? */
539	lacon(struct vars * v,
540	struct cnfa * pcnfa, /* parent cnfa */
541	chr *cp,
542	pcolor co) /* "color" of the lookahead constraint */
543	{
544	int n;
545	struct subre *sub;
546	struct dfa *d;
547	struct smalldfa sd;
548	chr *end;
549
550	n = co - pcnfa->ncolors;
551	assert(n < v->g->nlacons && v->g->lacons != NULL);
552	FDEBUG(("=== testing lacon %d\n", n));
553	sub = &v->g->lacons[n];
554	d = newdfa(v, &sub->cnfa, &v->g->cmap, &sd);
555	if (d == NULL)
556	{
557	ERR(REG_ESPACE);
558	return 0;
559	}
560	end = longest(v, d, cp, v->stop, (int *) NULL);
561	freedfa(d);
562	FDEBUG(("=== lacon %d match %d\n", n, (end != NULL)));
563	return (sub->subno) ? (end != NULL) : (end == NULL);
564	}
565
566	/*
567	* getvacant - get a vacant state set
568	* This routine clears out the inarcs and outarcs, but does not otherwise
569	* clear the innards of the state set -- that's up to the caller.
570	*/
571	static struct sset *
572	getvacant(struct vars * v, /* used only for debug flags */
573	struct dfa * d,
574	chr *cp,
575	chr *start)
576	{
577	int i;
578	struct sset *ss;
579	struct sset *p;
580	struct arcp ap;
581	struct arcp lastap;
582	color co;
583
584	ss = pickss(v, d, cp, start);
585	assert(!(ss->flags & LOCKED));
586
587	/* clear out its inarcs, including self-referential ones */
588	ap = ss->ins;
589	while ((p = ap.ss) != NULL)
590	{
591	co = ap.co;
592	FDEBUG(("zapping c%d's %ld outarc\n", p - d->ssets, (long) co));
593	p->outs[co] = NULL;
594	ap = p->inchain[co];
595	p->inchain[co].ss = NULL; /* paranoia */
596	}
597	ss->ins.ss = NULL;
598
599	/* take it off the inarc chains of the ssets reached by its outarcs */
600	for (i = 0; i < d->ncolors; i++)
601	{
602	p = ss->outs[i];
603	assert(p != ss); /* not self-referential */
604	if (p == NULL)
605	continue; /* NOTE CONTINUE */
606	FDEBUG(("del outarc %d from c%d's in chn\n", i, p - d->ssets));
607	if (p->ins.ss == ss && p->ins.co == i)
608	p->ins = ss->inchain[i];
609	else
610	{
611	assert(p->ins.ss != NULL);
612	for (ap = p->ins; ap.ss != NULL &&
613	!(ap.ss == ss && ap.co == i);
614	ap = ap.ss->inchain[ap.co])
615	lastap = ap;
616	assert(ap.ss != NULL);
617	lastap.ss->inchain[lastap.co] = ss->inchain[i];
618	}
619	ss->outs[i] = NULL;
620	ss->inchain[i].ss = NULL;
621	}
622
623	/* if ss was a success state, may need to remember location */
624	if ((ss->flags & POSTSTATE) && ss->lastseen != d->lastpost &&
625	(d->lastpost == NULL \|\| d->lastpost < ss->lastseen))
626	d->lastpost = ss->lastseen;
627
628	/* likewise for a no-progress state */
629	if ((ss->flags & NOPROGRESS) && ss->lastseen != d->lastnopr &&
630	(d->lastnopr == NULL \|\| d->lastnopr < ss->lastseen))
631	d->lastnopr = ss->lastseen;
632
633	return ss;
634	}
635
636	/*
637	* pickss - pick the next stateset to be used
638	*/
639	static struct sset *
640	pickss(struct vars * v, /* used only for debug flags */
641	struct dfa * d,
642	chr *cp,
643	chr *start)
644	{
645	int i;
646	struct sset *ss;
647	struct sset *end;
648	chr *ancient;
649
650	/* shortcut for cases where cache isn't full */
651	if (d->nssused < d->nssets)
652	{
653	i = d->nssused;
654	d->nssused++;
655	ss = &d->ssets[i];
656	FDEBUG(("new c%d\n", i));
657	/* set up innards */
658	ss->states = &d->statesarea[i * d->wordsper];
659	ss->flags = 0;
660	ss->ins.ss = NULL;
661	ss->ins.co = WHITE; /* give it some value */
662	ss->outs = &d->outsarea[i * d->ncolors];
663	ss->inchain = &d->incarea[i * d->ncolors];
664	for (i = 0; i < d->ncolors; i++)
665	{
666	ss->outs[i] = NULL;
667	ss->inchain[i].ss = NULL;
668	}
669	return ss;
670	}
671
672	/* look for oldest, or old enough anyway */
673	if (cp - start > d->nssets * 2 / 3) /* oldest 33% are expendable */
674	ancient = cp - d->nssets * 2 / 3;
675	else
676	ancient = start;
677	for (ss = d->search, end = &d->ssets[d->nssets]; ss < end; ss++)
678	if ((ss->lastseen == NULL \|\| ss->lastseen < ancient) &&
679	!(ss->flags & LOCKED))
680	{
681	d->search = ss + 1;
682	FDEBUG(("replacing c%d\n", ss - d->ssets));
683	return ss;
684	}
685	for (ss = d->ssets, end = d->search; ss < end; ss++)
686	if ((ss->lastseen == NULL \|\| ss->lastseen < ancient) &&
687	!(ss->flags & LOCKED))
688	{
689	d->search = ss + 1;
690	FDEBUG(("replacing c%d\n", ss - d->ssets));
691	return ss;
692	}
693
694	/* nobody's old enough?!? -- something's really wrong */
695	FDEBUG(("can't find victim to replace!\n"));
696	assert(NOTREACHED);
697	ERR(REG_ASSERT);
698	return d->ssets;
699	}