diff options
Diffstat (limited to 'generic/rege_dfa.c')
| -rw-r--r-- | generic/rege_dfa.c | 627 |
1 files changed, 627 insertions, 0 deletions
diff --git a/generic/rege_dfa.c b/generic/rege_dfa.c new file mode 100644 index 0000000..eb31ffc6 --- /dev/null +++ b/generic/rege_dfa.c @@ -0,0 +1,627 @@ +/* + * DFA routines + * This file is #included by regexec.c. + */ + +/* + - longest - longest-preferred matching engine + ^ static chr *longest(struct vars *, struct dfa *, chr *, chr *); + */ +static chr * /* endpoint, or NULL */ +longest(v, d, start, stop) +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 */ +{ + 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; + + /* 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) { + 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 = 0; i < d->nssused; 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 **); + */ +static chr * /* endpoint, or NULL */ +shortest(v, d, start, min, max, coldp) +struct vars *v; /* used only for debug and exec flags */ +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 */ +{ + 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; + chr *nopr; + int i; + + /* initialize */ + css = initialize(v, d, start); + cp = start; + + /* 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; + else if (ss->flags&POSTSTATE) { + 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)) + return NULL; + + /* find last no-progress state set, if any */ + nopr = d->lastnopr; + for (ss = d->ssets, i = 0; i < d->nssused; ss++, i++) + if ((ss->flags&NOPROGRESS) && nopr != ss->lastseen && + (nopr == NULL || nopr < ss->lastseen)) + nopr = ss->lastseen; + assert(nopr != NULL); + if (coldp != NULL) + *coldp = (nopr == v->start) ? nopr : nopr-1; + return cp; +} + +/* + - newdfa - set up a fresh DFA + ^ static struct dfa *newdfa(struct vars *, struct cnfa *, + ^ struct colormap *, struct smalldfa *); + */ +static struct dfa * +newdfa(v, cnfa, cm, small) +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®_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(d) +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(uv, n) +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(v, d, start) +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(v, d, css, co, cp, start) +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 didlacons; + + /* 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; + didlacons = 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 && + !ISBSET(d->work, ca->to) && + lacon(v, cnfa, cp, + ca->co)) { + BSET(d->work, ca->to); + dolacons = 1; + didlacons = 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)) { +#ifndef xxx +p->hash == h && +memcmp(VS(d->work), VS(p->states), + d->wordsper*sizeof(unsigned)) == 0) { +#endif + 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 (!didlacons) { /* lookahead conds. always cache miss */ + 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(v, pcnfa, cp, co) +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); + 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(v, d, cp, start) +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 *, struct dfa *, chr *, chr *); + */ +static struct sset * +pickss(v, d, cp, start) +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; +} |