/*
* 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.
*
*/
/*
- longest - longest-preferred matching engine
^ static chr *longest(struct vars *, struct dfa *, chr *, chr *, int *);
*/
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®_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®_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®_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 *shortest(struct vars *, struct dfa *, chr *, chr *, chr *,
^ chr **, int *);
*/
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®_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®_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®_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 *lastcold(struct vars *, struct dfa *);
*/
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 *, struct cnfa *,
^ struct colormap *, struct smalldfa *);
*/
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;
struct smalldfa *smallwas = sml;
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;
}
}
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->cptsmalloced = 0;
d->mallocarea = (smallwas == NULL) ? (char *)sml : 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®_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 *);
*/
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 *, int);
*/
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 *, struct dfa *, chr *);
*/
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 *miss(struct vars *, struct dfa *, struct sset *,
^ pcolor, chr *, chr *);
*/
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 lacon(struct vars *, struct cnfa *, chr *, pcolor);
*/
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 *, struct dfa *, chr *, chr *);
*/
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 = {NULL, 0}; /* silence gcc 4 warning */
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 *, struct dfa *, chr *, chr *);
*/
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;
}
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/
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