Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1106 insertions, 0 deletions

diff --git a/src/backend/regex/rege_dfa.c b/src/backend/regex/rege_dfa.c
new file mode 100644
index 0000000..ba1289c
--- /dev/null
+++ b/src/backend/regex/rege_dfa.c
@@ -0,0 +1,1106 @@
+/*
+ * 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.
+ *
+ * src/backend/regex/rege_dfa.c
+ *
+ */
+
+/*
+ * longest - longest-preferred matching engine
+ *
+ * On success, returns match endpoint address.  Returns NULL on no match.
+ * Internal errors also return NULL, with v->err set.
+ */
+static chr *
+longest(struct vars *v,
+		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;
+
+	/* prevent "uninitialized variable" warnings */
+	if (hitstopp != NULL)
+		*hitstopp = 0;
+
+	/* if this is a backref to a known string, just match against that */
+	if (d->backno >= 0)
+	{
+		assert((size_t) d->backno < v->nmatch);
+		if (v->pmatch[d->backno].rm_so >= 0)
+		{
+			cp = dfa_backref(v, d, start, start, stop, false);
+			if (cp == v->stop && stop == v->stop && hitstopp != NULL)
+				*hitstopp = 1;
+			return cp;
+		}
+	}
+
+	/* fast path for matchall NFAs */
+	if (d->cnfa->flags & MATCHALL)
+	{
+		size_t		nchr = stop - start;
+		size_t		maxmatchall = d->cnfa->maxmatchall;
+
+		if (nchr < d->cnfa->minmatchall)
+			return NULL;
+		if (maxmatchall == DUPINF)
+		{
+			if (stop == v->stop && hitstopp != NULL)
+				*hitstopp = 1;
+		}
+		else
+		{
+			if (stop == v->stop && nchr <= maxmatchall + 1 && hitstopp != NULL)
+				*hitstopp = 1;
+			if (nchr > maxmatchall)
+				return start + maxmatchall;
+		}
+		return stop;
+	}
+
+	/* initialize */
+	css = initialize(v, d, start);
+	if (css == NULL)
+		return NULL;
+	cp = start;
+
+	/* 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;
+
+	/*
+	 * This is the main text-scanning loop.  It seems worth having two copies
+	 * to avoid the overhead of REG_FTRACE tests here, even in REG_DEBUG
+	 * builds, when you're not actively tracing.
+	 */
+#ifdef REG_DEBUG
+	if (v->eflags & REG_FTRACE)
+	{
+		while (cp < realstop)
+		{
+			FDEBUG(("+++ at c%d +++\n", (int) (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
+#endif
+	{
+		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;
+		}
+	}
+
+	if (ISERR())
+		return NULL;
+
+	/* shutdown */
+	FDEBUG(("+++ shutdown at c%d +++\n", (int) (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);
+		if (ISERR())
+			return NULL;
+		/* 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
+ *
+ * On success, returns match endpoint address.  Returns NULL on no match.
+ * Internal errors also return NULL, with v->err set.
+ */
+static chr *
+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 non-NULL */
+		 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;
+
+	/* prevent "uninitialized variable" warnings */
+	if (coldp != NULL)
+		*coldp = NULL;
+	if (hitstopp != NULL)
+		*hitstopp = 0;
+
+	/* if this is a backref to a known string, just match against that */
+	if (d->backno >= 0)
+	{
+		assert((size_t) d->backno < v->nmatch);
+		if (v->pmatch[d->backno].rm_so >= 0)
+		{
+			cp = dfa_backref(v, d, start, min, max, true);
+			if (cp != NULL && coldp != NULL)
+				*coldp = start;
+			/* there is no case where we should set *hitstopp */
+			return cp;
+		}
+	}
+
+	/* fast path for matchall NFAs */
+	if (d->cnfa->flags & MATCHALL)
+	{
+		size_t		nchr = min - start;
+
+		if (d->cnfa->maxmatchall != DUPINF &&
+			nchr > d->cnfa->maxmatchall)
+			return NULL;
+		if ((max - start) < d->cnfa->minmatchall)
+			return NULL;
+		if (nchr < d->cnfa->minmatchall)
+			min = start + d->cnfa->minmatchall;
+		if (coldp != NULL)
+			*coldp = start;
+		/* there is no case where we should set *hitstopp */
+		return min;
+	}
+
+	/* initialize */
+	css = initialize(v, d, start);
+	if (css == NULL)
+		return NULL;
+	cp = start;
+
+	/* 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;
+
+	/*
+	 * This is the main text-scanning loop.  It seems worth having two copies
+	 * to avoid the overhead of REG_FTRACE tests here, even in REG_DEBUG
+	 * builds, when you're not actively tracing.
+	 */
+#ifdef REG_DEBUG
+	if (v->eflags & REG_FTRACE)
+	{
+		while (cp < realmax)
+		{
+			FDEBUG(("--- at c%d ---\n", (int) (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
+#endif
+	{
+		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;
+}
+
+/*
+ * matchuntil - incremental matching engine
+ *
+ * This is meant for use with a search-style NFA (that is, the pattern is
+ * known to act as though it had a leading .*).  We determine whether a
+ * match exists starting at v->start and ending at probe.  Multiple calls
+ * require only O(N) time not O(N^2) so long as the probe values are
+ * nondecreasing.  *lastcss and *lastcp must be initialized to NULL before
+ * starting a series of calls.
+ *
+ * Returns 1 if a match exists, 0 if not.
+ * Internal errors also return 0, with v->err set.
+ */
+static int
+matchuntil(struct vars *v,
+		   struct dfa *d,
+		   chr *probe,			/* we want to know if a match ends here */
+		   struct sset **lastcss,	/* state storage across calls */
+		   chr **lastcp)		/* state storage across calls */
+{
+	chr		   *cp = *lastcp;
+	color		co;
+	struct sset *css = *lastcss;
+	struct sset *ss;
+	struct colormap *cm = d->cm;
+
+	/* fast path for matchall NFAs */
+	if (d->cnfa->flags & MATCHALL)
+	{
+		size_t		nchr = probe - v->start;
+
+		if (nchr < d->cnfa->minmatchall)
+			return 0;
+		/* maxmatchall will always be infinity, cf. makesearch() */
+		assert(d->cnfa->maxmatchall == DUPINF);
+		return 1;
+	}
+
+	/* initialize and startup, or restart, if necessary */
+	if (cp == NULL || cp > probe)
+	{
+		cp = v->start;
+		css = initialize(v, d, cp);
+		if (css == NULL)
+			return 0;
+
+		FDEBUG((">>> startup >>>\n"));
+		co = d->cnfa->bos[(v->eflags & REG_NOTBOL) ? 0 : 1];
+		FDEBUG(("color %ld\n", (long) co));
+
+		css = miss(v, d, css, co, cp, v->start);
+		if (css == NULL)
+			return 0;
+		css->lastseen = cp;
+	}
+	else if (css == NULL)
+	{
+		/* we previously found that no match is possible beyond *lastcp */
+		return 0;
+	}
+	ss = css;
+
+	/*
+	 * This is the main text-scanning loop.  It seems worth having two copies
+	 * to avoid the overhead of REG_FTRACE tests here, even in REG_DEBUG
+	 * builds, when you're not actively tracing.
+	 */
+#ifdef REG_DEBUG
+	if (v->eflags & REG_FTRACE)
+	{
+		while (cp < probe)
+		{
+			FDEBUG((">>> at c%d >>>\n", (int) (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, v->start);
+				if (ss == NULL)
+					break;		/* NOTE BREAK OUT */
+			}
+			cp++;
+			ss->lastseen = cp;
+			css = ss;
+		}
+	}
+	else
+#endif
+	{
+		while (cp < probe)
+		{
+			co = GETCOLOR(cm, *cp);
+			ss = css->outs[co];
+			if (ss == NULL)
+			{
+				ss = miss(v, d, css, co, cp + 1, v->start);
+				if (ss == NULL)
+					break;		/* NOTE BREAK OUT */
+			}
+			cp++;
+			ss->lastseen = cp;
+			css = ss;
+		}
+	}
+
+	*lastcss = ss;
+	*lastcp = cp;
+
+	if (ss == NULL)
+		return 0;				/* impossible match, or internal error */
+
+	/* We need to process one more chr, or the EOS symbol, to check match */
+	if (cp < v->stop)
+	{
+		FDEBUG((">>> at c%d >>>\n", (int) (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, v->start);
+	}
+	else
+	{
+		assert(cp == 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, v->start);
+	}
+
+	if (ss == NULL || !(ss->flags & POSTSTATE))
+		return 0;
+
+	return 1;
+}
+
+/*
+ * dfa_backref - find best match length for a known backref string
+ *
+ * When the backref's referent is already available, we can deliver an exact
+ * answer with considerably less work than running the backref node's NFA.
+ *
+ * Return match endpoint for longest or shortest valid repeated match,
+ * or NULL if there is no valid match.
+ *
+ * Should be in sync with cbrdissect(), although that has the different task
+ * of checking a match to a predetermined section of the string.
+ */
+static chr *
+dfa_backref(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 */
+			bool shortest)
+{
+	int			n = d->backno;
+	int			backmin = d->backmin;
+	int			backmax = d->backmax;
+	size_t		numreps;
+	size_t		minreps;
+	size_t		maxreps;
+	size_t		brlen;
+	chr		   *brstring;
+	chr		   *p;
+
+	/* get the backreferenced string (caller should have checked this) */
+	if (v->pmatch[n].rm_so == -1)
+		return NULL;
+	brstring = v->start + v->pmatch[n].rm_so;
+	brlen = v->pmatch[n].rm_eo - v->pmatch[n].rm_so;
+
+	/* special-case zero-length backreference to avoid divide by zero */
+	if (brlen == 0)
+	{
+		/*
+		 * matches only a zero-length string, but any number of repetitions
+		 * can be considered to be present
+		 */
+		if (min == start && backmin <= backmax)
+			return start;
+		return NULL;
+	}
+
+	/*
+	 * convert min and max into numbers of possible repetitions of the backref
+	 * string, rounding appropriately
+	 */
+	if (min <= start)
+		minreps = 0;
+	else
+		minreps = (min - start - 1) / brlen + 1;
+	maxreps = (max - start) / brlen;
+
+	/* apply bounds, then see if there is any allowed match length */
+	if (minreps < backmin)
+		minreps = backmin;
+	if (backmax != DUPINF && maxreps > backmax)
+		maxreps = backmax;
+	if (maxreps < minreps)
+		return NULL;
+
+	/* quick exit if zero-repetitions match is valid and preferred */
+	if (shortest && minreps == 0)
+		return start;
+
+	/* okay, compare the actual string contents */
+	p = start;
+	numreps = 0;
+	while (numreps < maxreps)
+	{
+		if ((*v->g->compare) (brstring, p, brlen) != 0)
+			break;
+		p += brlen;
+		numreps++;
+		if (shortest && numreps >= minreps)
+			break;
+	}
+
+	if (numreps >= minreps)
+		return p;
+	return NULL;
+}
+
+/*
+ * 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
+ *
+ * Returns NULL (and sets v->err) on failure.
+ */
+static struct dfa *
+newdfa(struct vars *v,
+	   struct cnfa *cnfa,
+	   struct colormap *cm,
+	   struct smalldfa *sml)	/* preallocated space, may be NULL */
+{
+	struct dfa *d;
+	size_t		nss = cnfa->nstates * 2;
+	int			wordsper = (cnfa->nstates + UBITS - 1) / UBITS;
+	bool		ismalloced = false;
+
+	assert(cnfa != NULL && cnfa->nstates != 0);
+
+	if (nss <= FEWSTATES && cnfa->ncolors <= FEWCOLORS)
+	{
+		assert(wordsper == 1);
+		if (sml == NULL)
+		{
+			sml = (struct smalldfa *) MALLOC(sizeof(struct smalldfa));
+			if (sml == NULL)
+			{
+				ERR(REG_ESPACE);
+				return NULL;
+			}
+			ismalloced = true;
+		}
+		d = &sml->dfa;
+		d->ssets = sml->ssets;
+		d->statesarea = sml->statesarea;
+		d->work = &d->statesarea[nss];
+		d->outsarea = sml->outsarea;
+		d->incarea = sml->incarea;
+		d->ismalloced = ismalloced;
+		d->arraysmalloced = false;	/* not separately allocated, anyway */
+	}
+	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->ismalloced = true;
+		d->arraysmalloced = true;
+		/* now freedfa() will behave sanely */
+		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;
+	d->backno = -1;				/* may be set by caller */
+	d->backmin = d->backmax = 0;
+
+	/* initialization of sset fields is done as needed */
+
+	return d;
+}
+
+/*
+ * freedfa - free a DFA
+ */
+static void
+freedfa(struct dfa *d)
+{
+	if (d->arraysmalloced)
+	{
+		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->ismalloced)
+		FREE(d);
+}
+
+/*
+ * 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,
+		   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);
+		if (ss == NULL)
+			return NULL;
+		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 stateset cache miss
+ *
+ * css is the current stateset, co is the color of the current input character,
+ * cp points to the character after that (which is where we may need to test
+ * LACONs).  start does not affect matching behavior but is needed for pickss'
+ * heuristics about which stateset cache entry to replace.
+ *
+ * Ordinarily, returns the address of the next stateset (the one that is
+ * valid after consuming the input character).  Returns NULL if no valid
+ * NFA states remain, ie we have a certain match failure.
+ * Internal errors also return NULL, with v->err set.
+ */
+static struct sset *
+miss(struct vars *v,
+	 struct dfa *d,
+	 struct sset *css,
+	 color 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			ispseudocolor;
+	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"));
+
+	/*
+	 * Checking for operation cancel in the inner text search loop seems
+	 * unduly expensive.  As a compromise, check during cache misses.
+	 */
+	if (CANCEL_REQUESTED(v->re))
+	{
+		ERR(REG_CANCEL);
+		return NULL;
+	}
+
+	/*
+	 * What set of states would we end up in after consuming the co character?
+	 * We first consider PLAIN arcs that consume the character, and then look
+	 * to see what LACON arcs could be traversed after consuming it.
+	 */
+	for (i = 0; i < d->wordsper; i++)
+		d->work[i] = 0;			/* build new stateset bitmap in d->work */
+	ispseudocolor = d->cm->cd[co].flags & PSEUDO;
+	ispost = 0;
+	noprogress = 1;
+	gotstate = 0;
+	for (i = 0; i < d->nstates; i++)
+		if (ISBSET(css->states, i))
+			for (ca = cnfa->states[i]; ca->co != COLORLESS; ca++)
+				if (ca->co == co ||
+					(ca->co == RAINBOW && !ispseudocolor))
+				{
+					BSET(d->work, ca->to);
+					gotstate = 1;
+					if (ca->to == cnfa->post)
+						ispost = 1;
+					if (!(cnfa->stflags[ca->to] & CNFA_NOPROGRESS))
+						noprogress = 0;
+					FDEBUG(("%d -> %d\n", i, ca->to));
+				}
+	if (!gotstate)
+		return NULL;			/* character cannot reach any new state */
+	dolacons = (cnfa->flags & HASLACONS);
+	sawlacons = 0;
+	/* outer loop handles transitive closure of reachable-by-LACON states */
+	while (dolacons)
+	{
+		dolacons = 0;
+		for (i = 0; i < d->nstates; i++)
+			if (ISBSET(d->work, i))
+				for (ca = cnfa->states[i]; ca->co != COLORLESS; ca++)
+				{
+					if (ca->co < cnfa->ncolors)
+						continue;	/* not a LACON arc */
+					if (ISBSET(d->work, ca->to))
+						continue;	/* arc would be a no-op anyway */
+					sawlacons = 1;	/* this LACON affects our result */
+					if (!lacon(v, cnfa, cp, ca->co))
+					{
+						if (ISERR())
+							return NULL;
+						continue;	/* LACON arc cannot be traversed */
+					}
+					if (ISERR())
+						return NULL;
+					BSET(d->work, ca->to);
+					dolacons = 1;
+					if (ca->to == cnfa->post)
+						ispost = 1;
+					if (!(cnfa->stflags[ca->to] & CNFA_NOPROGRESS))
+						noprogress = 0;
+					FDEBUG(("%d :> %d\n", i, ca->to));
+				}
+	}
+	h = HASH(d->work, d->wordsper);
+
+	/* Is this stateset already 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", (int) (p - d->ssets)));
+			break;				/* NOTE BREAK OUT */
+		}
+	if (i == 0)
+	{							/* nope, need a new cache entry */
+		p = getvacant(v, d, cp, start);
+		if (p == NULL)
+			return NULL;
+		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 */
+	}
+
+	/*
+	 * Link new stateset to old, unless a LACON affected the result, in which
+	 * case we don't create the link.  That forces future transitions across
+	 * this same arc (same prior stateset and character color) to come through
+	 * miss() again, so that we can recheck the LACON(s), which might or might
+	 * not pass since context will be different.
+	 */
+	if (!sawlacons)
+	{
+		FDEBUG(("c%d[%d]->c%d\n",
+				(int) (css - d->ssets), co, (int) (p - d->ssets)));
+		css->outs[co] = p;
+		css->inchain[co] = p->ins;
+		p->ins.ss = css;
+		p->ins.co = co;
+	}
+	return p;
+}
+
+/*
+ * lacon - lookaround-constraint checker for miss()
+ */
+static int						/* predicate:  constraint satisfied? */
+lacon(struct vars *v,
+	  struct cnfa *pcnfa,		/* parent cnfa */
+	  chr *cp,
+	  color co)					/* "color" of the lookaround constraint */
+{
+	int			n;
+	struct subre *sub;
+	struct dfa *d;
+	chr		   *end;
+	int			satisfied;
+
+	/* Since this is recursive, it could be driven to stack overflow */
+	if (STACK_TOO_DEEP(v->re))
+	{
+		ERR(REG_ETOOBIG);
+		return 0;
+	}
+
+	n = co - pcnfa->ncolors;
+	assert(n > 0 && n < v->g->nlacons && v->g->lacons != NULL);
+	FDEBUG(("=== testing lacon %d\n", n));
+	sub = &v->g->lacons[n];
+	d = getladfa(v, n);
+	if (d == NULL)
+		return 0;
+	if (LATYPE_IS_AHEAD(sub->latype))
+	{
+		/* used to use longest() here, but shortest() could be much cheaper */
+		end = shortest(v, d, cp, cp, v->stop,
+					   (chr **) NULL, (int *) NULL);
+		satisfied = LATYPE_IS_POS(sub->latype) ? (end != NULL) : (end == NULL);
+	}
+	else
+	{
+		/*
+		 * To avoid doing O(N^2) work when repeatedly testing a lookbehind
+		 * constraint in an N-character string, we use matchuntil() which can
+		 * cache the DFA state across calls.  We only need to restart if the
+		 * probe point decreases, which is not common.  The NFA we're using is
+		 * a search NFA, so it doesn't mind scanning over stuff before the
+		 * nominal match.
+		 */
+		satisfied = matchuntil(v, d, cp, &v->lblastcss[n], &v->lblastcp[n]);
+		if (!LATYPE_IS_POS(sub->latype))
+			satisfied = !satisfied;
+	}
+	FDEBUG(("=== lacon %d satisfied %d\n", n, satisfied));
+	return satisfied;
+}
+
+/*
+ * 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,
+		  struct dfa *d,
+		  chr *cp,
+		  chr *start)
+{
+	int			i;
+	struct sset *ss;
+	struct sset *p;
+	struct arcp ap;
+	color		co;
+
+	ss = pickss(v, d, cp, start);
+	if (ss == NULL)
+		return NULL;
+	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", (int) (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, (int) (p - d->ssets)));
+		if (p->ins.ss == ss && p->ins.co == i)
+			p->ins = ss->inchain[i];
+		else
+		{
+			struct arcp lastap = {NULL, 0};
+
+			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,
+	   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", (int) (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", (int) (ss - d->ssets)));
+			return ss;
+		}
+
+	/* nobody's old enough?!? -- something's really wrong */
+	FDEBUG(("cannot find victim to replace!\n"));
+	ERR(REG_ASSERT);
+	return NULL;
+}