| /* |
| * 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. |
| * |
| * $PostgreSQL: pgsql/src/backend/regex/rege_dfa.c,v 1.8 2007/10/06 16:05:54 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", (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 |
| 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", (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); |
| /* 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", (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 |
| 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", (int) (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", |
| (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 = (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; |
| 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", (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, /* 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", (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")); |
| assert(NOTREACHED); |
| ERR(REG_ASSERT); |
| return d->ssets; |
| } |