Replace regular expression package with Henry Spencer's latest version

(extracted from Tcl 8.4.1 release, as Henry still hasn't got round to
making it a separate library).  This solves a performance problem for
multibyte, as well as upgrading our regexp support to match recent Tcl
and nearly match recent Perl.

1 files changed, 655 insertions, 0 deletions

diff --git a/src/backend/regex/rege_dfa.c b/src/backend/regex/rege_dfa.c
new file mode 100644
index 00000000000..3bdfc2ab182
--- /dev/null
+++ b/src/backend/regex/rege_dfa.c
@@ -0,0 +1,655 @@
+/*
+ * 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: /cvsroot/pgsql/src/backend/regex/rege_dfa.c,v 1.1 2003/02/05 17:41:33 tgl Exp $
+ *
+ */
+
+/*
+ * 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;
+}