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Diffstat (limited to 'src/backend/regex/regc_nfa.c')
| -rw-r--r-- | src/backend/regex/regc_nfa.c | 3882 |
1 files changed, 3882 insertions, 0 deletions
diff --git a/src/backend/regex/regc_nfa.c b/src/backend/regex/regc_nfa.c new file mode 100644 index 0000000..60fb0be --- /dev/null +++ b/src/backend/regex/regc_nfa.c @@ -0,0 +1,3882 @@ +/* + * NFA utilities. + * This file is #included by regcomp.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/regc_nfa.c + * + * + * One or two things that technically ought to be in here + * are actually in color.c, thanks to some incestuous relationships in + * the color chains. + */ + +#define NISERR() VISERR(nfa->v) +#define NERR(e) VERR(nfa->v, (e)) + + +/* + * newnfa - set up an NFA + */ +static struct nfa * /* the NFA, or NULL */ +newnfa(struct vars *v, + struct colormap *cm, + struct nfa *parent) /* NULL if primary NFA */ +{ + struct nfa *nfa; + + nfa = (struct nfa *) MALLOC(sizeof(struct nfa)); + if (nfa == NULL) + { + ERR(REG_ESPACE); + return NULL; + } + + /* Make the NFA minimally valid, so freenfa() will behave sanely */ + nfa->states = NULL; + nfa->slast = NULL; + nfa->freestates = NULL; + nfa->freearcs = NULL; + nfa->lastsb = NULL; + nfa->lastab = NULL; + nfa->lastsbused = 0; + nfa->lastabused = 0; + nfa->nstates = 0; + nfa->cm = cm; + nfa->v = v; + nfa->bos[0] = nfa->bos[1] = COLORLESS; + nfa->eos[0] = nfa->eos[1] = COLORLESS; + nfa->flags = 0; + nfa->minmatchall = nfa->maxmatchall = -1; + nfa->parent = parent; /* Precedes newfstate so parent is valid. */ + + /* Create required infrastructure */ + nfa->post = newfstate(nfa, '@'); /* number 0 */ + nfa->pre = newfstate(nfa, '>'); /* number 1 */ + nfa->init = newstate(nfa); /* may become invalid later */ + nfa->final = newstate(nfa); + if (ISERR()) + { + freenfa(nfa); + return NULL; + } + rainbow(nfa, nfa->cm, PLAIN, COLORLESS, nfa->pre, nfa->init); + newarc(nfa, '^', 1, nfa->pre, nfa->init); + newarc(nfa, '^', 0, nfa->pre, nfa->init); + rainbow(nfa, nfa->cm, PLAIN, COLORLESS, nfa->final, nfa->post); + newarc(nfa, '$', 1, nfa->final, nfa->post); + newarc(nfa, '$', 0, nfa->final, nfa->post); + + if (ISERR()) + { + freenfa(nfa); + return NULL; + } + return nfa; +} + +/* + * freenfa - free an entire NFA + */ +static void +freenfa(struct nfa *nfa) +{ + struct statebatch *sb; + struct statebatch *sbnext; + struct arcbatch *ab; + struct arcbatch *abnext; + + for (sb = nfa->lastsb; sb != NULL; sb = sbnext) + { + sbnext = sb->next; + nfa->v->spaceused -= STATEBATCHSIZE(sb->nstates); + FREE(sb); + } + nfa->lastsb = NULL; + for (ab = nfa->lastab; ab != NULL; ab = abnext) + { + abnext = ab->next; + nfa->v->spaceused -= ARCBATCHSIZE(ab->narcs); + FREE(ab); + } + nfa->lastab = NULL; + + nfa->nstates = -1; + FREE(nfa); +} + +/* + * newstate - allocate an NFA state, with zero flag value + */ +static struct state * /* NULL on error */ +newstate(struct nfa *nfa) +{ + struct state *s; + + /* + * This is a handy place to check for operation cancel during regex + * compilation, since no code path will go very long without making a new + * state or arc. + */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return NULL; + } + + /* first, recycle anything that's on the freelist */ + if (nfa->freestates != NULL) + { + s = nfa->freestates; + nfa->freestates = s->next; + } + /* otherwise, is there anything left in the last statebatch? */ + else if (nfa->lastsb != NULL && nfa->lastsbused < nfa->lastsb->nstates) + { + s = &nfa->lastsb->s[nfa->lastsbused++]; + } + /* otherwise, need to allocate a new statebatch */ + else + { + struct statebatch *newSb; + size_t nstates; + + if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE) + { + NERR(REG_ETOOBIG); + return NULL; + } + nstates = (nfa->lastsb != NULL) ? nfa->lastsb->nstates * 2 : FIRSTSBSIZE; + if (nstates > MAXSBSIZE) + nstates = MAXSBSIZE; + newSb = (struct statebatch *) MALLOC(STATEBATCHSIZE(nstates)); + if (newSb == NULL) + { + NERR(REG_ESPACE); + return NULL; + } + nfa->v->spaceused += STATEBATCHSIZE(nstates); + newSb->nstates = nstates; + newSb->next = nfa->lastsb; + nfa->lastsb = newSb; + nfa->lastsbused = 1; + s = &newSb->s[0]; + } + + assert(nfa->nstates >= 0); + s->no = nfa->nstates++; + s->flag = 0; + if (nfa->states == NULL) + nfa->states = s; + s->nins = 0; + s->ins = NULL; + s->nouts = 0; + s->outs = NULL; + s->tmp = NULL; + s->next = NULL; + if (nfa->slast != NULL) + { + assert(nfa->slast->next == NULL); + nfa->slast->next = s; + } + s->prev = nfa->slast; + nfa->slast = s; + return s; +} + +/* + * newfstate - allocate an NFA state with a specified flag value + */ +static struct state * /* NULL on error */ +newfstate(struct nfa *nfa, int flag) +{ + struct state *s; + + s = newstate(nfa); + if (s != NULL) + s->flag = (char) flag; + return s; +} + +/* + * dropstate - delete a state's inarcs and outarcs and free it + */ +static void +dropstate(struct nfa *nfa, + struct state *s) +{ + struct arc *a; + + while ((a = s->ins) != NULL) + freearc(nfa, a); + while ((a = s->outs) != NULL) + freearc(nfa, a); + freestate(nfa, s); +} + +/* + * freestate - free a state, which has no in-arcs or out-arcs + */ +static void +freestate(struct nfa *nfa, + struct state *s) +{ + assert(s != NULL); + assert(s->nins == 0 && s->nouts == 0); + + s->no = FREESTATE; + s->flag = 0; + if (s->next != NULL) + s->next->prev = s->prev; + else + { + assert(s == nfa->slast); + nfa->slast = s->prev; + } + if (s->prev != NULL) + s->prev->next = s->next; + else + { + assert(s == nfa->states); + nfa->states = s->next; + } + s->prev = NULL; + s->next = nfa->freestates; /* don't delete it, put it on the free list */ + nfa->freestates = s; +} + +/* + * newarc - set up a new arc within an NFA + * + * This function checks to make sure that no duplicate arcs are created. + * In general we never want duplicates. + * + * However: in principle, a RAINBOW arc is redundant with any plain arc + * (unless that arc is for a pseudocolor). But we don't try to recognize + * that redundancy, either here or in allied operations such as moveins(). + * The pseudocolor consideration makes that more costly than it seems worth. + */ +static void +newarc(struct nfa *nfa, + int t, + color co, + struct state *from, + struct state *to) +{ + struct arc *a; + + assert(from != NULL && to != NULL); + + /* + * This is a handy place to check for operation cancel during regex + * compilation, since no code path will go very long without making a new + * state or arc. + */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return; + } + + /* check for duplicate arc, using whichever chain is shorter */ + if (from->nouts <= to->nins) + { + for (a = from->outs; a != NULL; a = a->outchain) + if (a->to == to && a->co == co && a->type == t) + return; + } + else + { + for (a = to->ins; a != NULL; a = a->inchain) + if (a->from == from && a->co == co && a->type == t) + return; + } + + /* no dup, so create the arc */ + createarc(nfa, t, co, from, to); +} + +/* + * createarc - create a new arc within an NFA + * + * This function must *only* be used after verifying that there is no existing + * identical arc (same type/color/from/to). + */ +static void +createarc(struct nfa *nfa, + int t, + color co, + struct state *from, + struct state *to) +{ + struct arc *a; + + a = allocarc(nfa); + if (NISERR()) + return; + assert(a != NULL); + + a->type = t; + a->co = co; + a->to = to; + a->from = from; + + /* + * Put the new arc on the beginning, not the end, of the chains; it's + * simpler here, and freearc() is the same cost either way. See also the + * logic in moveins() and its cohorts, as well as fixempties(). + */ + a->inchain = to->ins; + a->inchainRev = NULL; + if (to->ins) + to->ins->inchainRev = a; + to->ins = a; + a->outchain = from->outs; + a->outchainRev = NULL; + if (from->outs) + from->outs->outchainRev = a; + from->outs = a; + + from->nouts++; + to->nins++; + + if (COLORED(a) && nfa->parent == NULL) + colorchain(nfa->cm, a); +} + +/* + * allocarc - allocate a new arc within an NFA + */ +static struct arc * /* NULL for failure */ +allocarc(struct nfa *nfa) +{ + struct arc *a; + + /* first, recycle anything that's on the freelist */ + if (nfa->freearcs != NULL) + { + a = nfa->freearcs; + nfa->freearcs = a->freechain; + } + /* otherwise, is there anything left in the last arcbatch? */ + else if (nfa->lastab != NULL && nfa->lastabused < nfa->lastab->narcs) + { + a = &nfa->lastab->a[nfa->lastabused++]; + } + /* otherwise, need to allocate a new arcbatch */ + else + { + struct arcbatch *newAb; + size_t narcs; + + if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE) + { + NERR(REG_ETOOBIG); + return NULL; + } + narcs = (nfa->lastab != NULL) ? nfa->lastab->narcs * 2 : FIRSTABSIZE; + if (narcs > MAXABSIZE) + narcs = MAXABSIZE; + newAb = (struct arcbatch *) MALLOC(ARCBATCHSIZE(narcs)); + if (newAb == NULL) + { + NERR(REG_ESPACE); + return NULL; + } + nfa->v->spaceused += ARCBATCHSIZE(narcs); + newAb->narcs = narcs; + newAb->next = nfa->lastab; + nfa->lastab = newAb; + nfa->lastabused = 1; + a = &newAb->a[0]; + } + + return a; +} + +/* + * freearc - free an arc + */ +static void +freearc(struct nfa *nfa, + struct arc *victim) +{ + struct state *from = victim->from; + struct state *to = victim->to; + struct arc *predecessor; + + assert(victim->type != 0); + + /* take it off color chain if necessary */ + if (COLORED(victim) && nfa->parent == NULL) + uncolorchain(nfa->cm, victim); + + /* take it off source's out-chain */ + assert(from != NULL); + predecessor = victim->outchainRev; + if (predecessor == NULL) + { + assert(from->outs == victim); + from->outs = victim->outchain; + } + else + { + assert(predecessor->outchain == victim); + predecessor->outchain = victim->outchain; + } + if (victim->outchain != NULL) + { + assert(victim->outchain->outchainRev == victim); + victim->outchain->outchainRev = predecessor; + } + from->nouts--; + + /* take it off target's in-chain */ + assert(to != NULL); + predecessor = victim->inchainRev; + if (predecessor == NULL) + { + assert(to->ins == victim); + to->ins = victim->inchain; + } + else + { + assert(predecessor->inchain == victim); + predecessor->inchain = victim->inchain; + } + if (victim->inchain != NULL) + { + assert(victim->inchain->inchainRev == victim); + victim->inchain->inchainRev = predecessor; + } + to->nins--; + + /* clean up and place on NFA's free list */ + victim->type = 0; + victim->from = NULL; /* precautions... */ + victim->to = NULL; + victim->inchain = NULL; + victim->inchainRev = NULL; + victim->outchain = NULL; + victim->outchainRev = NULL; + victim->freechain = nfa->freearcs; + nfa->freearcs = victim; +} + +/* + * changearcsource - flip an arc to have a different from state + * + * Caller must have verified that there is no pre-existing duplicate arc. + */ +static void +changearcsource(struct arc *a, struct state *newfrom) +{ + struct state *oldfrom = a->from; + struct arc *predecessor; + + assert(oldfrom != newfrom); + + /* take it off old source's out-chain */ + assert(oldfrom != NULL); + predecessor = a->outchainRev; + if (predecessor == NULL) + { + assert(oldfrom->outs == a); + oldfrom->outs = a->outchain; + } + else + { + assert(predecessor->outchain == a); + predecessor->outchain = a->outchain; + } + if (a->outchain != NULL) + { + assert(a->outchain->outchainRev == a); + a->outchain->outchainRev = predecessor; + } + oldfrom->nouts--; + + a->from = newfrom; + + /* prepend it to new source's out-chain */ + a->outchain = newfrom->outs; + a->outchainRev = NULL; + if (newfrom->outs) + newfrom->outs->outchainRev = a; + newfrom->outs = a; + newfrom->nouts++; +} + +/* + * changearctarget - flip an arc to have a different to state + * + * Caller must have verified that there is no pre-existing duplicate arc. + */ +static void +changearctarget(struct arc *a, struct state *newto) +{ + struct state *oldto = a->to; + struct arc *predecessor; + + assert(oldto != newto); + + /* take it off old target's in-chain */ + assert(oldto != NULL); + predecessor = a->inchainRev; + if (predecessor == NULL) + { + assert(oldto->ins == a); + oldto->ins = a->inchain; + } + else + { + assert(predecessor->inchain == a); + predecessor->inchain = a->inchain; + } + if (a->inchain != NULL) + { + assert(a->inchain->inchainRev == a); + a->inchain->inchainRev = predecessor; + } + oldto->nins--; + + a->to = newto; + + /* prepend it to new target's in-chain */ + a->inchain = newto->ins; + a->inchainRev = NULL; + if (newto->ins) + newto->ins->inchainRev = a; + newto->ins = a; + newto->nins++; +} + +/* + * hasnonemptyout - Does state have a non-EMPTY out arc? + */ +static int +hasnonemptyout(struct state *s) +{ + struct arc *a; + + for (a = s->outs; a != NULL; a = a->outchain) + { + if (a->type != EMPTY) + return 1; + } + return 0; +} + +/* + * findarc - find arc, if any, from given source with given type and color + * If there is more than one such arc, the result is random. + */ +static struct arc * +findarc(struct state *s, + int type, + color co) +{ + struct arc *a; + + for (a = s->outs; a != NULL; a = a->outchain) + if (a->type == type && a->co == co) + return a; + return NULL; +} + +/* + * cparc - allocate a new arc within an NFA, copying details from old one + */ +static void +cparc(struct nfa *nfa, + struct arc *oa, + struct state *from, + struct state *to) +{ + newarc(nfa, oa->type, oa->co, from, to); +} + +/* + * sortins - sort the in arcs of a state by from/color/type + */ +static void +sortins(struct nfa *nfa, + struct state *s) +{ + struct arc **sortarray; + struct arc *a; + int n = s->nins; + int i; + + if (n <= 1) + return; /* nothing to do */ + /* make an array of arc pointers ... */ + sortarray = (struct arc **) MALLOC(n * sizeof(struct arc *)); + if (sortarray == NULL) + { + NERR(REG_ESPACE); + return; + } + i = 0; + for (a = s->ins; a != NULL; a = a->inchain) + sortarray[i++] = a; + assert(i == n); + /* ... sort the array */ + qsort(sortarray, n, sizeof(struct arc *), sortins_cmp); + /* ... and rebuild arc list in order */ + /* it seems worth special-casing first and last items to simplify loop */ + a = sortarray[0]; + s->ins = a; + a->inchain = sortarray[1]; + a->inchainRev = NULL; + for (i = 1; i < n - 1; i++) + { + a = sortarray[i]; + a->inchain = sortarray[i + 1]; + a->inchainRev = sortarray[i - 1]; + } + a = sortarray[i]; + a->inchain = NULL; + a->inchainRev = sortarray[i - 1]; + FREE(sortarray); +} + +static int +sortins_cmp(const void *a, const void *b) +{ + const struct arc *aa = *((const struct arc *const *) a); + const struct arc *bb = *((const struct arc *const *) b); + + /* we check the fields in the order they are most likely to be different */ + if (aa->from->no < bb->from->no) + return -1; + if (aa->from->no > bb->from->no) + return 1; + if (aa->co < bb->co) + return -1; + if (aa->co > bb->co) + return 1; + if (aa->type < bb->type) + return -1; + if (aa->type > bb->type) + return 1; + return 0; +} + +/* + * sortouts - sort the out arcs of a state by to/color/type + */ +static void +sortouts(struct nfa *nfa, + struct state *s) +{ + struct arc **sortarray; + struct arc *a; + int n = s->nouts; + int i; + + if (n <= 1) + return; /* nothing to do */ + /* make an array of arc pointers ... */ + sortarray = (struct arc **) MALLOC(n * sizeof(struct arc *)); + if (sortarray == NULL) + { + NERR(REG_ESPACE); + return; + } + i = 0; + for (a = s->outs; a != NULL; a = a->outchain) + sortarray[i++] = a; + assert(i == n); + /* ... sort the array */ + qsort(sortarray, n, sizeof(struct arc *), sortouts_cmp); + /* ... and rebuild arc list in order */ + /* it seems worth special-casing first and last items to simplify loop */ + a = sortarray[0]; + s->outs = a; + a->outchain = sortarray[1]; + a->outchainRev = NULL; + for (i = 1; i < n - 1; i++) + { + a = sortarray[i]; + a->outchain = sortarray[i + 1]; + a->outchainRev = sortarray[i - 1]; + } + a = sortarray[i]; + a->outchain = NULL; + a->outchainRev = sortarray[i - 1]; + FREE(sortarray); +} + +static int +sortouts_cmp(const void *a, const void *b) +{ + const struct arc *aa = *((const struct arc *const *) a); + const struct arc *bb = *((const struct arc *const *) b); + + /* we check the fields in the order they are most likely to be different */ + if (aa->to->no < bb->to->no) + return -1; + if (aa->to->no > bb->to->no) + return 1; + if (aa->co < bb->co) + return -1; + if (aa->co > bb->co) + return 1; + if (aa->type < bb->type) + return -1; + if (aa->type > bb->type) + return 1; + return 0; +} + +/* + * Common decision logic about whether to use arc-by-arc operations or + * sort/merge. If there's just a few source arcs we cannot recoup the + * cost of sorting the destination arc list, no matter how large it is. + * Otherwise, limit the number of arc-by-arc comparisons to about 1000 + * (a somewhat arbitrary choice, but the breakeven point would probably + * be machine dependent anyway). + */ +#define BULK_ARC_OP_USE_SORT(nsrcarcs, ndestarcs) \ + ((nsrcarcs) < 4 ? 0 : ((nsrcarcs) > 32 || (ndestarcs) > 32)) + +/* + * moveins - move all in arcs of a state to another state + * + * You might think this could be done better by just updating the + * existing arcs, and you would be right if it weren't for the need + * for duplicate suppression, which makes it easier to just make new + * ones to exploit the suppression built into newarc. + * + * However, if we have a whole lot of arcs to deal with, retail duplicate + * checks become too slow. In that case we proceed by sorting and merging + * the arc lists, and then we can indeed just update the arcs in-place. + * + * On the other hand, it's also true that this is frequently called with + * a brand-new newState that has no existing in-arcs. In that case, + * de-duplication is unnecessary, so we can just blindly move all the arcs. + */ +static void +moveins(struct nfa *nfa, + struct state *oldState, + struct state *newState) +{ + assert(oldState != newState); + + if (newState->nins == 0) + { + /* No need for de-duplication */ + struct arc *a; + + while ((a = oldState->ins) != NULL) + { + createarc(nfa, a->type, a->co, a->from, newState); + freearc(nfa, a); + } + } + else if (!BULK_ARC_OP_USE_SORT(oldState->nins, newState->nins)) + { + /* With not too many arcs, just do them one at a time */ + struct arc *a; + + while ((a = oldState->ins) != NULL) + { + cparc(nfa, a, a->from, newState); + freearc(nfa, a); + } + } + else + { + /* + * With many arcs, use a sort-merge approach. Note changearctarget() + * will put the arc onto the front of newState's chain, so it does not + * break our walk through the sorted part of the chain. + */ + struct arc *oa; + struct arc *na; + + /* + * Because we bypass newarc() in this code path, we'd better include a + * cancel check. + */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return; + } + + sortins(nfa, oldState); + sortins(nfa, newState); + if (NISERR()) + return; /* might have failed to sort */ + oa = oldState->ins; + na = newState->ins; + while (oa != NULL && na != NULL) + { + struct arc *a = oa; + + switch (sortins_cmp(&oa, &na)) + { + case -1: + /* newState does not have anything matching oa */ + oa = oa->inchain; + + /* + * Rather than doing createarc+freearc, we can just unlink + * and relink the existing arc struct. + */ + changearctarget(a, newState); + break; + case 0: + /* match, advance in both lists */ + oa = oa->inchain; + na = na->inchain; + /* ... and drop duplicate arc from oldState */ + freearc(nfa, a); + break; + case +1: + /* advance only na; oa might have a match later */ + na = na->inchain; + break; + default: + assert(NOTREACHED); + } + } + while (oa != NULL) + { + /* newState does not have anything matching oa */ + struct arc *a = oa; + + oa = oa->inchain; + changearctarget(a, newState); + } + } + + assert(oldState->nins == 0); + assert(oldState->ins == NULL); +} + +/* + * copyins - copy in arcs of a state to another state + * + * The comments for moveins() apply here as well. However, in current + * usage, this is *only* called with brand-new target states, so that + * only the "no need for de-duplication" code path is ever reached. + * We keep the rest #ifdef'd out in case it's needed in the future. + */ +static void +copyins(struct nfa *nfa, + struct state *oldState, + struct state *newState) +{ + assert(oldState != newState); + assert(newState->nins == 0); /* see comment above */ + + if (newState->nins == 0) + { + /* No need for de-duplication */ + struct arc *a; + + for (a = oldState->ins; a != NULL; a = a->inchain) + createarc(nfa, a->type, a->co, a->from, newState); + } +#ifdef NOT_USED /* see comment above */ + else if (!BULK_ARC_OP_USE_SORT(oldState->nins, newState->nins)) + { + /* With not too many arcs, just do them one at a time */ + struct arc *a; + + for (a = oldState->ins; a != NULL; a = a->inchain) + cparc(nfa, a, a->from, newState); + } + else + { + /* + * With many arcs, use a sort-merge approach. Note that createarc() + * will put new arcs onto the front of newState's chain, so it does + * not break our walk through the sorted part of the chain. + */ + struct arc *oa; + struct arc *na; + + /* + * Because we bypass newarc() in this code path, we'd better include a + * cancel check. + */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return; + } + + sortins(nfa, oldState); + sortins(nfa, newState); + if (NISERR()) + return; /* might have failed to sort */ + oa = oldState->ins; + na = newState->ins; + while (oa != NULL && na != NULL) + { + struct arc *a = oa; + + switch (sortins_cmp(&oa, &na)) + { + case -1: + /* newState does not have anything matching oa */ + oa = oa->inchain; + createarc(nfa, a->type, a->co, a->from, newState); + break; + case 0: + /* match, advance in both lists */ + oa = oa->inchain; + na = na->inchain; + break; + case +1: + /* advance only na; oa might have a match later */ + na = na->inchain; + break; + default: + assert(NOTREACHED); + } + } + while (oa != NULL) + { + /* newState does not have anything matching oa */ + struct arc *a = oa; + + oa = oa->inchain; + createarc(nfa, a->type, a->co, a->from, newState); + } + } +#endif /* NOT_USED */ +} + +/* + * mergeins - merge a list of inarcs into a state + * + * This is much like copyins, but the source arcs are listed in an array, + * and are not guaranteed unique. It's okay to clobber the array contents. + */ +static void +mergeins(struct nfa *nfa, + struct state *s, + struct arc **arcarray, + int arccount) +{ + struct arc *na; + int i; + int j; + + if (arccount <= 0) + return; + + /* + * Because we bypass newarc() in this code path, we'd better include a + * cancel check. + */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return; + } + + /* Sort existing inarcs as well as proposed new ones */ + sortins(nfa, s); + if (NISERR()) + return; /* might have failed to sort */ + + qsort(arcarray, arccount, sizeof(struct arc *), sortins_cmp); + + /* + * arcarray very likely includes dups, so we must eliminate them. (This + * could be folded into the next loop, but it's not worth the trouble.) + */ + j = 0; + for (i = 1; i < arccount; i++) + { + switch (sortins_cmp(&arcarray[j], &arcarray[i])) + { + case -1: + /* non-dup */ + arcarray[++j] = arcarray[i]; + break; + case 0: + /* dup */ + break; + default: + /* trouble */ + assert(NOTREACHED); + } + } + arccount = j + 1; + + /* + * Now merge into s' inchain. Note that createarc() will put new arcs + * onto the front of s's chain, so it does not break our walk through the + * sorted part of the chain. + */ + i = 0; + na = s->ins; + while (i < arccount && na != NULL) + { + struct arc *a = arcarray[i]; + + switch (sortins_cmp(&a, &na)) + { + case -1: + /* s does not have anything matching a */ + createarc(nfa, a->type, a->co, a->from, s); + i++; + break; + case 0: + /* match, advance in both lists */ + i++; + na = na->inchain; + break; + case +1: + /* advance only na; array might have a match later */ + na = na->inchain; + break; + default: + assert(NOTREACHED); + } + } + while (i < arccount) + { + /* s does not have anything matching a */ + struct arc *a = arcarray[i]; + + createarc(nfa, a->type, a->co, a->from, s); + i++; + } +} + +/* + * moveouts - move all out arcs of a state to another state + * + * See comments for moveins() + */ +static void +moveouts(struct nfa *nfa, + struct state *oldState, + struct state *newState) +{ + assert(oldState != newState); + + if (newState->nouts == 0) + { + /* No need for de-duplication */ + struct arc *a; + + while ((a = oldState->outs) != NULL) + { + createarc(nfa, a->type, a->co, newState, a->to); + freearc(nfa, a); + } + } + else if (!BULK_ARC_OP_USE_SORT(oldState->nouts, newState->nouts)) + { + /* With not too many arcs, just do them one at a time */ + struct arc *a; + + while ((a = oldState->outs) != NULL) + { + cparc(nfa, a, newState, a->to); + freearc(nfa, a); + } + } + else + { + /* + * With many arcs, use a sort-merge approach. Note changearcsource() + * will put the arc onto the front of newState's chain, so it does not + * break our walk through the sorted part of the chain. + */ + struct arc *oa; + struct arc *na; + + /* + * Because we bypass newarc() in this code path, we'd better include a + * cancel check. + */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return; + } + + sortouts(nfa, oldState); + sortouts(nfa, newState); + if (NISERR()) + return; /* might have failed to sort */ + oa = oldState->outs; + na = newState->outs; + while (oa != NULL && na != NULL) + { + struct arc *a = oa; + + switch (sortouts_cmp(&oa, &na)) + { + case -1: + /* newState does not have anything matching oa */ + oa = oa->outchain; + + /* + * Rather than doing createarc+freearc, we can just unlink + * and relink the existing arc struct. + */ + changearcsource(a, newState); + break; + case 0: + /* match, advance in both lists */ + oa = oa->outchain; + na = na->outchain; + /* ... and drop duplicate arc from oldState */ + freearc(nfa, a); + break; + case +1: + /* advance only na; oa might have a match later */ + na = na->outchain; + break; + default: + assert(NOTREACHED); + } + } + while (oa != NULL) + { + /* newState does not have anything matching oa */ + struct arc *a = oa; + + oa = oa->outchain; + changearcsource(a, newState); + } + } + + assert(oldState->nouts == 0); + assert(oldState->outs == NULL); +} + +/* + * copyouts - copy out arcs of a state to another state + * + * See comments for copyins() + */ +static void +copyouts(struct nfa *nfa, + struct state *oldState, + struct state *newState) +{ + assert(oldState != newState); + assert(newState->nouts == 0); /* see comment above */ + + if (newState->nouts == 0) + { + /* No need for de-duplication */ + struct arc *a; + + for (a = oldState->outs; a != NULL; a = a->outchain) + createarc(nfa, a->type, a->co, newState, a->to); + } +#ifdef NOT_USED /* see comment above */ + else if (!BULK_ARC_OP_USE_SORT(oldState->nouts, newState->nouts)) + { + /* With not too many arcs, just do them one at a time */ + struct arc *a; + + for (a = oldState->outs; a != NULL; a = a->outchain) + cparc(nfa, a, newState, a->to); + } + else + { + /* + * With many arcs, use a sort-merge approach. Note that createarc() + * will put new arcs onto the front of newState's chain, so it does + * not break our walk through the sorted part of the chain. + */ + struct arc *oa; + struct arc *na; + + /* + * Because we bypass newarc() in this code path, we'd better include a + * cancel check. + */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return; + } + + sortouts(nfa, oldState); + sortouts(nfa, newState); + if (NISERR()) + return; /* might have failed to sort */ + oa = oldState->outs; + na = newState->outs; + while (oa != NULL && na != NULL) + { + struct arc *a = oa; + + switch (sortouts_cmp(&oa, &na)) + { + case -1: + /* newState does not have anything matching oa */ + oa = oa->outchain; + createarc(nfa, a->type, a->co, newState, a->to); + break; + case 0: + /* match, advance in both lists */ + oa = oa->outchain; + na = na->outchain; + break; + case +1: + /* advance only na; oa might have a match later */ + na = na->outchain; + break; + default: + assert(NOTREACHED); + } + } + while (oa != NULL) + { + /* newState does not have anything matching oa */ + struct arc *a = oa; + + oa = oa->outchain; + createarc(nfa, a->type, a->co, newState, a->to); + } + } +#endif /* NOT_USED */ +} + +/* + * cloneouts - copy out arcs of a state to another state pair, modifying type + * + * This is only used to convert PLAIN arcs to AHEAD/BEHIND arcs, which share + * the same interpretation of "co". It wouldn't be sensible with LACONs. + */ +static void +cloneouts(struct nfa *nfa, + struct state *old, + struct state *from, + struct state *to, + int type) +{ + struct arc *a; + + assert(old != from); + assert(type == AHEAD || type == BEHIND); + + for (a = old->outs; a != NULL; a = a->outchain) + { + assert(a->type == PLAIN); + newarc(nfa, type, a->co, from, to); + } +} + +/* + * delsub - delete a sub-NFA, updating subre pointers if necessary + * + * This uses a recursive traversal of the sub-NFA, marking already-seen + * states using their tmp pointer. + */ +static void +delsub(struct nfa *nfa, + struct state *lp, /* the sub-NFA goes from here... */ + struct state *rp) /* ...to here, *not* inclusive */ +{ + assert(lp != rp); + + rp->tmp = rp; /* mark end */ + + deltraverse(nfa, lp, lp); + if (NISERR()) + return; /* asserts might not hold after failure */ + assert(lp->nouts == 0 && rp->nins == 0); /* did the job */ + assert(lp->no != FREESTATE && rp->no != FREESTATE); /* no more */ + + rp->tmp = NULL; /* unmark end */ + lp->tmp = NULL; /* and begin, marked by deltraverse */ +} + +/* + * deltraverse - the recursive heart of delsub + * This routine's basic job is to destroy all out-arcs of the state. + */ +static void +deltraverse(struct nfa *nfa, + struct state *leftend, + struct state *s) +{ + struct arc *a; + struct state *to; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return; + } + + if (s->nouts == 0) + return; /* nothing to do */ + if (s->tmp != NULL) + return; /* already in progress */ + + s->tmp = s; /* mark as in progress */ + + while ((a = s->outs) != NULL) + { + to = a->to; + deltraverse(nfa, leftend, to); + if (NISERR()) + return; /* asserts might not hold after failure */ + assert(to->nouts == 0 || to->tmp != NULL); + freearc(nfa, a); + if (to->nins == 0 && to->tmp == NULL) + { + assert(to->nouts == 0); + freestate(nfa, to); + } + } + + assert(s->no != FREESTATE); /* we're still here */ + assert(s == leftend || s->nins != 0); /* and still reachable */ + assert(s->nouts == 0); /* but have no outarcs */ + + s->tmp = NULL; /* we're done here */ +} + +/* + * dupnfa - duplicate sub-NFA + * + * Another recursive traversal, this time using tmp to point to duplicates + * as well as mark already-seen states. (You knew there was a reason why + * it's a state pointer, didn't you? :-)) + */ +static void +dupnfa(struct nfa *nfa, + struct state *start, /* duplicate of subNFA starting here */ + struct state *stop, /* and stopping here */ + struct state *from, /* stringing duplicate from here */ + struct state *to) /* to here */ +{ + if (start == stop) + { + newarc(nfa, EMPTY, 0, from, to); + return; + } + + stop->tmp = to; + duptraverse(nfa, start, from); + /* done, except for clearing out the tmp pointers */ + + stop->tmp = NULL; + cleartraverse(nfa, start); +} + +/* + * duptraverse - recursive heart of dupnfa + */ +static void +duptraverse(struct nfa *nfa, + struct state *s, + struct state *stmp) /* s's duplicate, or NULL */ +{ + struct arc *a; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return; + } + + if (s->tmp != NULL) + return; /* already done */ + + s->tmp = (stmp == NULL) ? newstate(nfa) : stmp; + if (s->tmp == NULL) + { + assert(NISERR()); + return; + } + + for (a = s->outs; a != NULL && !NISERR(); a = a->outchain) + { + duptraverse(nfa, a->to, (struct state *) NULL); + if (NISERR()) + break; + assert(a->to->tmp != NULL); + cparc(nfa, a, s->tmp, a->to->tmp); + } +} + +/* + * removeconstraints - remove any constraints in an NFA + * + * Constraint arcs are replaced by empty arcs, essentially treating all + * constraints as automatically satisfied. + */ +static void +removeconstraints(struct nfa *nfa, + struct state *start, /* process subNFA starting here */ + struct state *stop) /* and stopping here */ +{ + if (start == stop) + return; + + stop->tmp = stop; + removetraverse(nfa, start); + /* done, except for clearing out the tmp pointers */ + + stop->tmp = NULL; + cleartraverse(nfa, start); +} + +/* + * removetraverse - recursive heart of removeconstraints + */ +static void +removetraverse(struct nfa *nfa, + struct state *s) +{ + struct arc *a; + struct arc *oa; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return; + } + + if (s->tmp != NULL) + return; /* already done */ + + s->tmp = s; + for (a = s->outs; a != NULL && !NISERR(); a = oa) + { + removetraverse(nfa, a->to); + if (NISERR()) + break; + oa = a->outchain; + switch (a->type) + { + case PLAIN: + case EMPTY: + /* nothing to do */ + break; + case AHEAD: + case BEHIND: + case '^': + case '$': + case LACON: + /* replace it */ + newarc(nfa, EMPTY, 0, s, a->to); + freearc(nfa, a); + break; + default: + NERR(REG_ASSERT); + break; + } + } +} + +/* + * cleartraverse - recursive cleanup for algorithms that leave tmp ptrs set + */ +static void +cleartraverse(struct nfa *nfa, + struct state *s) +{ + struct arc *a; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return; + } + + if (s->tmp == NULL) + return; + s->tmp = NULL; + + for (a = s->outs; a != NULL; a = a->outchain) + cleartraverse(nfa, a->to); +} + +/* + * single_color_transition - does getting from s1 to s2 cross one PLAIN arc? + * + * If traversing from s1 to s2 requires a single PLAIN match (possibly of any + * of a set of colors), return a state whose outarc list contains only PLAIN + * arcs of those color(s). Otherwise return NULL. + * + * This is used before optimizing the NFA, so there may be EMPTY arcs, which + * we should ignore; the possibility of an EMPTY is why the result state could + * be different from s1. + * + * It's worth troubling to handle multiple parallel PLAIN arcs here because a + * bracket construct such as [abc] might yield either one or several parallel + * PLAIN arcs depending on earlier atoms in the expression. We'd rather that + * that implementation detail not create user-visible performance differences. + */ +static struct state * +single_color_transition(struct state *s1, struct state *s2) +{ + struct arc *a; + + /* Ignore leading EMPTY arc, if any */ + if (s1->nouts == 1 && s1->outs->type == EMPTY) + s1 = s1->outs->to; + /* Likewise for any trailing EMPTY arc */ + if (s2->nins == 1 && s2->ins->type == EMPTY) + s2 = s2->ins->from; + /* Perhaps we could have a single-state loop in between, if so reject */ + if (s1 == s2) + return NULL; + /* s1 must have at least one outarc... */ + if (s1->outs == NULL) + return NULL; + /* ... and they must all be PLAIN arcs to s2 */ + for (a = s1->outs; a != NULL; a = a->outchain) + { + if (a->type != PLAIN || a->to != s2) + return NULL; + } + /* OK, return s1 as the possessor of the relevant outarcs */ + return s1; +} + +/* + * specialcolors - fill in special colors for an NFA + */ +static void +specialcolors(struct nfa *nfa) +{ + /* false colors for BOS, BOL, EOS, EOL */ + if (nfa->parent == NULL) + { + nfa->bos[0] = pseudocolor(nfa->cm); + nfa->bos[1] = pseudocolor(nfa->cm); + nfa->eos[0] = pseudocolor(nfa->cm); + nfa->eos[1] = pseudocolor(nfa->cm); + } + else + { + assert(nfa->parent->bos[0] != COLORLESS); + nfa->bos[0] = nfa->parent->bos[0]; + assert(nfa->parent->bos[1] != COLORLESS); + nfa->bos[1] = nfa->parent->bos[1]; + assert(nfa->parent->eos[0] != COLORLESS); + nfa->eos[0] = nfa->parent->eos[0]; + assert(nfa->parent->eos[1] != COLORLESS); + nfa->eos[1] = nfa->parent->eos[1]; + } +} + +/* + * optimize - optimize an NFA + * + * The main goal of this function is not so much "optimization" (though it + * does try to get rid of useless NFA states) as reducing the NFA to a form + * the regex executor can handle. The executor, and indeed the cNFA format + * that is its input, can only handle PLAIN and LACON arcs. The output of + * the regex parser also includes EMPTY (do-nothing) arcs, as well as + * ^, $, AHEAD, and BEHIND constraint arcs, which we must get rid of here. + * We first get rid of EMPTY arcs and then deal with the constraint arcs. + * The hardest part of either job is to get rid of circular loops of the + * target arc type. We would have to do that in any case, though, as such a + * loop would otherwise allow the executor to cycle through the loop endlessly + * without making any progress in the input string. + */ +static long /* re_info bits */ +optimize(struct nfa *nfa, + FILE *f) /* for debug output; NULL none */ +{ +#ifdef REG_DEBUG + int verbose = (f != NULL) ? 1 : 0; + + if (verbose) + fprintf(f, "\ninitial cleanup:\n"); +#endif + cleanup(nfa); /* may simplify situation */ +#ifdef REG_DEBUG + if (verbose) + dumpnfa(nfa, f); + if (verbose) + fprintf(f, "\nempties:\n"); +#endif + fixempties(nfa, f); /* get rid of EMPTY arcs */ +#ifdef REG_DEBUG + if (verbose) + fprintf(f, "\nconstraints:\n"); +#endif + fixconstraintloops(nfa, f); /* get rid of constraint loops */ + pullback(nfa, f); /* pull back constraints backward */ + pushfwd(nfa, f); /* push fwd constraints forward */ +#ifdef REG_DEBUG + if (verbose) + fprintf(f, "\nfinal cleanup:\n"); +#endif + cleanup(nfa); /* final tidying */ +#ifdef REG_DEBUG + if (verbose) + dumpnfa(nfa, f); +#endif + return analyze(nfa); /* and analysis */ +} + +/* + * pullback - pull back constraints backward to eliminate them + */ +static void +pullback(struct nfa *nfa, + FILE *f) /* for debug output; NULL none */ +{ + struct state *s; + struct state *nexts; + struct arc *a; + struct arc *nexta; + struct state *intermediates; + int progress; + + /* find and pull until there are no more */ + do + { + progress = 0; + for (s = nfa->states; s != NULL && !NISERR(); s = nexts) + { + nexts = s->next; + intermediates = NULL; + for (a = s->outs; a != NULL && !NISERR(); a = nexta) + { + nexta = a->outchain; + if (a->type == '^' || a->type == BEHIND) + if (pull(nfa, a, &intermediates)) + progress = 1; + } + /* clear tmp fields of intermediate states created here */ + while (intermediates != NULL) + { + struct state *ns = intermediates->tmp; + + intermediates->tmp = NULL; + intermediates = ns; + } + /* if s is now useless, get rid of it */ + if ((s->nins == 0 || s->nouts == 0) && !s->flag) + dropstate(nfa, s); + } + if (progress && f != NULL) + dumpnfa(nfa, f); + } while (progress && !NISERR()); + if (NISERR()) + return; + + /* + * Any ^ constraints we were able to pull to the start state can now be + * replaced by PLAIN arcs referencing the BOS or BOL colors. There should + * be no other ^ or BEHIND arcs left in the NFA, though we do not check + * that here (compact() will fail if so). + */ + for (a = nfa->pre->outs; a != NULL; a = nexta) + { + nexta = a->outchain; + if (a->type == '^') + { + assert(a->co == 0 || a->co == 1); + newarc(nfa, PLAIN, nfa->bos[a->co], a->from, a->to); + freearc(nfa, a); + } + } +} + +/* + * pull - pull a back constraint backward past its source state + * + * Returns 1 if successful (which it always is unless the source is the + * start state or we have an internal error), 0 if nothing happened. + * + * A significant property of this function is that it deletes no pre-existing + * states, and no outarcs of the constraint's from state other than the given + * constraint arc. This makes the loops in pullback() safe, at the cost that + * we may leave useless states behind. Therefore, we leave it to pullback() + * to delete such states. + * + * If the from state has multiple back-constraint outarcs, and/or multiple + * compatible constraint inarcs, we only need to create one new intermediate + * state per combination of predecessor and successor states. *intermediates + * points to a list of such intermediate states for this from state (chained + * through their tmp fields). + */ +static int +pull(struct nfa *nfa, + struct arc *con, + struct state **intermediates) +{ + struct state *from = con->from; + struct state *to = con->to; + struct arc *a; + struct arc *nexta; + struct state *s; + + assert(from != to); /* should have gotten rid of this earlier */ + if (from->flag) /* can't pull back beyond start */ + return 0; + if (from->nins == 0) + { /* unreachable */ + freearc(nfa, con); + return 1; + } + + /* + * First, clone from state if necessary to avoid other outarcs. This may + * seem wasteful, but it simplifies the logic, and we'll get rid of the + * clone state again at the bottom. + */ + if (from->nouts > 1) + { + s = newstate(nfa); + if (NISERR()) + return 0; + copyins(nfa, from, s); /* duplicate inarcs */ + cparc(nfa, con, s, to); /* move constraint arc */ + freearc(nfa, con); + if (NISERR()) + return 0; + from = s; + con = from->outs; + } + assert(from->nouts == 1); + + /* propagate the constraint into the from state's inarcs */ + for (a = from->ins; a != NULL && !NISERR(); a = nexta) + { + nexta = a->inchain; + switch (combine(nfa, con, a)) + { + case INCOMPATIBLE: /* destroy the arc */ + freearc(nfa, a); + break; + case SATISFIED: /* no action needed */ + break; + case COMPATIBLE: /* swap the two arcs, more or less */ + /* need an intermediate state, but might have one already */ + for (s = *intermediates; s != NULL; s = s->tmp) + { + assert(s->nins > 0 && s->nouts > 0); + if (s->ins->from == a->from && s->outs->to == to) + break; + } + if (s == NULL) + { + s = newstate(nfa); + if (NISERR()) + return 0; + s->tmp = *intermediates; + *intermediates = s; + } + cparc(nfa, con, a->from, s); + cparc(nfa, a, s, to); + freearc(nfa, a); + break; + case REPLACEARC: /* replace arc's color */ + newarc(nfa, a->type, con->co, a->from, to); + freearc(nfa, a); + break; + default: + assert(NOTREACHED); + break; + } + } + + /* remaining inarcs, if any, incorporate the constraint */ + moveins(nfa, from, to); + freearc(nfa, con); + /* from state is now useless, but we leave it to pullback() to clean up */ + return 1; +} + +/* + * pushfwd - push forward constraints forward to eliminate them + */ +static void +pushfwd(struct nfa *nfa, + FILE *f) /* for debug output; NULL none */ +{ + struct state *s; + struct state *nexts; + struct arc *a; + struct arc *nexta; + struct state *intermediates; + int progress; + + /* find and push until there are no more */ + do + { + progress = 0; + for (s = nfa->states; s != NULL && !NISERR(); s = nexts) + { + nexts = s->next; + intermediates = NULL; + for (a = s->ins; a != NULL && !NISERR(); a = nexta) + { + nexta = a->inchain; + if (a->type == '$' || a->type == AHEAD) + if (push(nfa, a, &intermediates)) + progress = 1; + } + /* clear tmp fields of intermediate states created here */ + while (intermediates != NULL) + { + struct state *ns = intermediates->tmp; + + intermediates->tmp = NULL; + intermediates = ns; + } + /* if s is now useless, get rid of it */ + if ((s->nins == 0 || s->nouts == 0) && !s->flag) + dropstate(nfa, s); + } + if (progress && f != NULL) + dumpnfa(nfa, f); + } while (progress && !NISERR()); + if (NISERR()) + return; + + /* + * Any $ constraints we were able to push to the post state can now be + * replaced by PLAIN arcs referencing the EOS or EOL colors. There should + * be no other $ or AHEAD arcs left in the NFA, though we do not check + * that here (compact() will fail if so). + */ + for (a = nfa->post->ins; a != NULL; a = nexta) + { + nexta = a->inchain; + if (a->type == '$') + { + assert(a->co == 0 || a->co == 1); + newarc(nfa, PLAIN, nfa->eos[a->co], a->from, a->to); + freearc(nfa, a); + } + } +} + +/* + * push - push a forward constraint forward past its destination state + * + * Returns 1 if successful (which it always is unless the destination is the + * post state or we have an internal error), 0 if nothing happened. + * + * A significant property of this function is that it deletes no pre-existing + * states, and no inarcs of the constraint's to state other than the given + * constraint arc. This makes the loops in pushfwd() safe, at the cost that + * we may leave useless states behind. Therefore, we leave it to pushfwd() + * to delete such states. + * + * If the to state has multiple forward-constraint inarcs, and/or multiple + * compatible constraint outarcs, we only need to create one new intermediate + * state per combination of predecessor and successor states. *intermediates + * points to a list of such intermediate states for this to state (chained + * through their tmp fields). + */ +static int +push(struct nfa *nfa, + struct arc *con, + struct state **intermediates) +{ + struct state *from = con->from; + struct state *to = con->to; + struct arc *a; + struct arc *nexta; + struct state *s; + + assert(to != from); /* should have gotten rid of this earlier */ + if (to->flag) /* can't push forward beyond end */ + return 0; + if (to->nouts == 0) + { /* dead end */ + freearc(nfa, con); + return 1; + } + + /* + * First, clone to state if necessary to avoid other inarcs. This may + * seem wasteful, but it simplifies the logic, and we'll get rid of the + * clone state again at the bottom. + */ + if (to->nins > 1) + { + s = newstate(nfa); + if (NISERR()) + return 0; + copyouts(nfa, to, s); /* duplicate outarcs */ + cparc(nfa, con, from, s); /* move constraint arc */ + freearc(nfa, con); + if (NISERR()) + return 0; + to = s; + con = to->ins; + } + assert(to->nins == 1); + + /* propagate the constraint into the to state's outarcs */ + for (a = to->outs; a != NULL && !NISERR(); a = nexta) + { + nexta = a->outchain; + switch (combine(nfa, con, a)) + { + case INCOMPATIBLE: /* destroy the arc */ + freearc(nfa, a); + break; + case SATISFIED: /* no action needed */ + break; + case COMPATIBLE: /* swap the two arcs, more or less */ + /* need an intermediate state, but might have one already */ + for (s = *intermediates; s != NULL; s = s->tmp) + { + assert(s->nins > 0 && s->nouts > 0); + if (s->ins->from == from && s->outs->to == a->to) + break; + } + if (s == NULL) + { + s = newstate(nfa); + if (NISERR()) + return 0; + s->tmp = *intermediates; + *intermediates = s; + } + cparc(nfa, con, s, a->to); + cparc(nfa, a, from, s); + freearc(nfa, a); + break; + case REPLACEARC: /* replace arc's color */ + newarc(nfa, a->type, con->co, from, a->to); + freearc(nfa, a); + break; + default: + assert(NOTREACHED); + break; + } + } + + /* remaining outarcs, if any, incorporate the constraint */ + moveouts(nfa, to, from); + freearc(nfa, con); + /* to state is now useless, but we leave it to pushfwd() to clean up */ + return 1; +} + +/* + * combine - constraint lands on an arc, what happens? + * + * #def INCOMPATIBLE 1 // destroys arc + * #def SATISFIED 2 // constraint satisfied + * #def COMPATIBLE 3 // compatible but not satisfied yet + * #def REPLACEARC 4 // replace arc's color with constraint color + */ +static int +combine(struct nfa *nfa, + struct arc *con, + struct arc *a) +{ +#define CA(ct,at) (((ct)<<CHAR_BIT) | (at)) + + switch (CA(con->type, a->type)) + { + case CA('^', PLAIN): /* newlines are handled separately */ + case CA('$', PLAIN): + return INCOMPATIBLE; + break; + case CA(AHEAD, PLAIN): /* color constraints meet colors */ + case CA(BEHIND, PLAIN): + if (con->co == a->co) + return SATISFIED; + if (con->co == RAINBOW) + { + /* con is satisfied unless arc's color is a pseudocolor */ + if (!(nfa->cm->cd[a->co].flags & PSEUDO)) + return SATISFIED; + } + else if (a->co == RAINBOW) + { + /* con is incompatible if it's for a pseudocolor */ + /* (this is hypothetical; we make no such constraints today) */ + if (nfa->cm->cd[con->co].flags & PSEUDO) + return INCOMPATIBLE; + /* otherwise, constraint constrains arc to be only its color */ + return REPLACEARC; + } + return INCOMPATIBLE; + break; + case CA('^', '^'): /* collision, similar constraints */ + case CA('$', '$'): + if (con->co == a->co) /* true duplication */ + return SATISFIED; + return INCOMPATIBLE; + break; + case CA(AHEAD, AHEAD): /* collision, similar constraints */ + case CA(BEHIND, BEHIND): + if (con->co == a->co) /* true duplication */ + return SATISFIED; + if (con->co == RAINBOW) + { + /* con is satisfied unless arc's color is a pseudocolor */ + if (!(nfa->cm->cd[a->co].flags & PSEUDO)) + return SATISFIED; + } + else if (a->co == RAINBOW) + { + /* con is incompatible if it's for a pseudocolor */ + /* (this is hypothetical; we make no such constraints today) */ + if (nfa->cm->cd[con->co].flags & PSEUDO) + return INCOMPATIBLE; + /* otherwise, constraint constrains arc to be only its color */ + return REPLACEARC; + } + return INCOMPATIBLE; + break; + case CA('^', BEHIND): /* collision, dissimilar constraints */ + case CA(BEHIND, '^'): + case CA('$', AHEAD): + case CA(AHEAD, '$'): + return INCOMPATIBLE; + break; + case CA('^', '$'): /* constraints passing each other */ + case CA('^', AHEAD): + case CA(BEHIND, '$'): + case CA(BEHIND, AHEAD): + case CA('$', '^'): + case CA('$', BEHIND): + case CA(AHEAD, '^'): + case CA(AHEAD, BEHIND): + case CA('^', LACON): + case CA(BEHIND, LACON): + case CA('$', LACON): + case CA(AHEAD, LACON): + return COMPATIBLE; + break; + } + assert(NOTREACHED); + return INCOMPATIBLE; /* for benefit of blind compilers */ +} + +/* + * fixempties - get rid of EMPTY arcs + */ +static void +fixempties(struct nfa *nfa, + FILE *f) /* for debug output; NULL none */ +{ + struct state *s; + struct state *s2; + struct state *nexts; + struct arc *a; + struct arc *nexta; + int totalinarcs; + struct arc **inarcsorig; + struct arc **arcarray; + int arccount; + int prevnins; + int nskip; + + /* + * First, get rid of any states whose sole out-arc is an EMPTY, since + * they're basically just aliases for their successor. The parsing + * algorithm creates enough of these that it's worth special-casing this. + */ + for (s = nfa->states; s != NULL && !NISERR(); s = nexts) + { + nexts = s->next; + if (s->flag || s->nouts != 1) + continue; + a = s->outs; + assert(a != NULL && a->outchain == NULL); + if (a->type != EMPTY) + continue; + if (s != a->to) + moveins(nfa, s, a->to); + dropstate(nfa, s); + } + + /* + * Similarly, get rid of any state with a single EMPTY in-arc, by folding + * it into its predecessor. + */ + for (s = nfa->states; s != NULL && !NISERR(); s = nexts) + { + nexts = s->next; + /* while we're at it, ensure tmp fields are clear for next step */ + assert(s->tmp == NULL); + if (s->flag || s->nins != 1) + continue; + a = s->ins; + assert(a != NULL && a->inchain == NULL); + if (a->type != EMPTY) + continue; + if (s != a->from) + moveouts(nfa, s, a->from); + dropstate(nfa, s); + } + + if (NISERR()) + return; + + /* + * For each remaining NFA state, find all other states from which it is + * reachable by a chain of one or more EMPTY arcs. Then generate new arcs + * that eliminate the need for each such chain. + * + * We could replace a chain of EMPTY arcs that leads from a "from" state + * to a "to" state either by pushing non-EMPTY arcs forward (linking + * directly from "from"'s predecessors to "to") or by pulling them back + * (linking directly from "from" to "to"'s successors). We choose to + * always do the former; this choice is somewhat arbitrary, but the + * approach below requires that we uniformly do one or the other. + * + * Suppose we have a chain of N successive EMPTY arcs (where N can easily + * approach the size of the NFA). All of the intermediate states must + * have additional inarcs and outarcs, else they'd have been removed by + * the steps above. Assuming their inarcs are mostly not empties, we will + * add O(N^2) arcs to the NFA, since a non-EMPTY inarc leading to any one + * state in the chain must be duplicated to lead to all its successor + * states as well. So there is no hope of doing less than O(N^2) work; + * however, we should endeavor to keep the big-O cost from being even + * worse than that, which it can easily become without care. In + * particular, suppose we were to copy all S1's inarcs forward to S2, and + * then also to S3, and then later we consider pushing S2's inarcs forward + * to S3. If we include the arcs already copied from S1 in that, we'd be + * doing O(N^3) work. (The duplicate-arc elimination built into newarc() + * and its cohorts would get rid of the extra arcs, but not without cost.) + * + * We can avoid this cost by treating only arcs that existed at the start + * of this phase as candidates to be pushed forward. To identify those, + * we remember the first inarc each state had to start with. We rely on + * the fact that newarc() and friends put new arcs on the front of their + * to-states' inchains, and that this phase never deletes arcs, so that + * the original arcs must be the last arcs in their to-states' inchains. + * + * So the process here is that, for each state in the NFA, we gather up + * all non-EMPTY inarcs of states that can reach the target state via + * EMPTY arcs. We then sort, de-duplicate, and merge these arcs into the + * target state's inchain. (We can safely use sort-merge for this as long + * as we update each state's original-arcs pointer after we add arcs to + * it; the sort step of mergeins probably changed the order of the old + * arcs.) + * + * Another refinement worth making is that, because we only add non-EMPTY + * arcs during this phase, and all added arcs have the same from-state as + * the non-EMPTY arc they were cloned from, we know ahead of time that any + * states having only EMPTY outarcs will be useless for lack of outarcs + * after we drop the EMPTY arcs. (They cannot gain non-EMPTY outarcs if + * they had none to start with.) So we need not bother to update the + * inchains of such states at all. + */ + + /* Remember the states' first original inarcs */ + /* ... and while at it, count how many old inarcs there are altogether */ + inarcsorig = (struct arc **) MALLOC(nfa->nstates * sizeof(struct arc *)); + if (inarcsorig == NULL) + { + NERR(REG_ESPACE); + return; + } + totalinarcs = 0; + for (s = nfa->states; s != NULL; s = s->next) + { + inarcsorig[s->no] = s->ins; + totalinarcs += s->nins; + } + + /* + * Create a workspace for accumulating the inarcs to be added to the + * current target state. totalinarcs is probably a considerable + * overestimate of the space needed, but the NFA is unlikely to be large + * enough at this point to make it worth being smarter. + */ + arcarray = (struct arc **) MALLOC(totalinarcs * sizeof(struct arc *)); + if (arcarray == NULL) + { + NERR(REG_ESPACE); + FREE(inarcsorig); + return; + } + + /* And iterate over the target states */ + for (s = nfa->states; s != NULL && !NISERR(); s = s->next) + { + /* Ignore target states without non-EMPTY outarcs, per note above */ + if (!s->flag && !hasnonemptyout(s)) + continue; + + /* Find predecessor states and accumulate their original inarcs */ + arccount = 0; + for (s2 = emptyreachable(nfa, s, s, inarcsorig); s2 != s; s2 = nexts) + { + /* Add s2's original inarcs to arcarray[], but ignore empties */ + for (a = inarcsorig[s2->no]; a != NULL; a = a->inchain) + { + if (a->type != EMPTY) + arcarray[arccount++] = a; + } + + /* Reset the tmp fields as we walk back */ + nexts = s2->tmp; + s2->tmp = NULL; + } + s->tmp = NULL; + assert(arccount <= totalinarcs); + + /* Remember how many original inarcs this state has */ + prevnins = s->nins; + + /* Add non-duplicate inarcs to target state */ + mergeins(nfa, s, arcarray, arccount); + + /* Now we must update the state's inarcsorig pointer */ + nskip = s->nins - prevnins; + a = s->ins; + while (nskip-- > 0) + a = a->inchain; + inarcsorig[s->no] = a; + } + + FREE(arcarray); + FREE(inarcsorig); + + if (NISERR()) + return; + + /* + * Now remove all the EMPTY arcs, since we don't need them anymore. + */ + for (s = nfa->states; s != NULL; s = s->next) + { + for (a = s->outs; a != NULL; a = nexta) + { + nexta = a->outchain; + if (a->type == EMPTY) + freearc(nfa, a); + } + } + + /* + * And remove any states that have become useless. (This cleanup is not + * very thorough, and would be even less so if we tried to combine it with + * the previous step; but cleanup() will take care of anything we miss.) + */ + for (s = nfa->states; s != NULL; s = nexts) + { + nexts = s->next; + if ((s->nins == 0 || s->nouts == 0) && !s->flag) + dropstate(nfa, s); + } + + if (f != NULL) + dumpnfa(nfa, f); +} + +/* + * emptyreachable - recursively find all states that can reach s by EMPTY arcs + * + * The return value is the last such state found. Its tmp field links back + * to the next-to-last such state, and so on back to s, so that all these + * states can be located without searching the whole NFA. + * + * Since this is only used in fixempties(), we pass in the inarcsorig[] array + * maintained by that function. This lets us skip over all new inarcs, which + * are certainly not EMPTY arcs. + * + * The maximum recursion depth here is equal to the length of the longest + * loop-free chain of EMPTY arcs, which is surely no more than the size of + * the NFA ... but that could still be enough to cause trouble. + */ +static struct state * +emptyreachable(struct nfa *nfa, + struct state *s, + struct state *lastfound, + struct arc **inarcsorig) +{ + struct arc *a; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return lastfound; + } + + s->tmp = lastfound; + lastfound = s; + for (a = inarcsorig[s->no]; a != NULL; a = a->inchain) + { + if (a->type == EMPTY && a->from->tmp == NULL) + lastfound = emptyreachable(nfa, a->from, lastfound, inarcsorig); + } + return lastfound; +} + +/* + * isconstraintarc - detect whether an arc is of a constraint type + */ +static inline int +isconstraintarc(struct arc *a) +{ + switch (a->type) + { + case '^': + case '$': + case BEHIND: + case AHEAD: + case LACON: + return 1; + } + return 0; +} + +/* + * hasconstraintout - does state have a constraint out arc? + */ +static int +hasconstraintout(struct state *s) +{ + struct arc *a; + + for (a = s->outs; a != NULL; a = a->outchain) + { + if (isconstraintarc(a)) + return 1; + } + return 0; +} + +/* + * fixconstraintloops - get rid of loops containing only constraint arcs + * + * A loop of states that contains only constraint arcs is useless, since + * passing around the loop represents no forward progress. Moreover, it + * would cause infinite looping in pullback/pushfwd, so we need to get rid + * of such loops before doing that. + */ +static void +fixconstraintloops(struct nfa *nfa, + FILE *f) /* for debug output; NULL none */ +{ + struct state *s; + struct state *nexts; + struct arc *a; + struct arc *nexta; + int hasconstraints; + + /* + * In the trivial case of a state that loops to itself, we can just drop + * the constraint arc altogether. This is worth special-casing because + * such loops are far more common than loops containing multiple states. + * While we're at it, note whether any constraint arcs survive. + */ + hasconstraints = 0; + for (s = nfa->states; s != NULL && !NISERR(); s = nexts) + { + nexts = s->next; + /* while we're at it, ensure tmp fields are clear for next step */ + assert(s->tmp == NULL); + for (a = s->outs; a != NULL && !NISERR(); a = nexta) + { + nexta = a->outchain; + if (isconstraintarc(a)) + { + if (a->to == s) + freearc(nfa, a); + else + hasconstraints = 1; + } + } + /* If we removed all the outarcs, the state is useless. */ + if (s->nouts == 0 && !s->flag) + dropstate(nfa, s); + } + + /* Nothing to do if no remaining constraint arcs */ + if (NISERR() || !hasconstraints) + return; + + /* + * Starting from each remaining NFA state, search outwards for a + * constraint loop. If we find a loop, break the loop, then start the + * search over. (We could possibly retain some state from the first scan, + * but it would complicate things greatly, and multi-state constraint + * loops are rare enough that it's not worth optimizing the case.) + */ +restart: + for (s = nfa->states; s != NULL && !NISERR(); s = s->next) + { + if (findconstraintloop(nfa, s)) + goto restart; + } + + if (NISERR()) + return; + + /* + * Now remove any states that have become useless. (This cleanup is not + * very thorough, and would be even less so if we tried to combine it with + * the previous step; but cleanup() will take care of anything we miss.) + * + * Because findconstraintloop intentionally doesn't reset all tmp fields, + * we have to clear them after it's done. This is a convenient place to + * do that, too. + */ + for (s = nfa->states; s != NULL; s = nexts) + { + nexts = s->next; + s->tmp = NULL; + if ((s->nins == 0 || s->nouts == 0) && !s->flag) + dropstate(nfa, s); + } + + if (f != NULL) + dumpnfa(nfa, f); +} + +/* + * findconstraintloop - recursively find a loop of constraint arcs + * + * If we find a loop, break it by calling breakconstraintloop(), then + * return 1; otherwise return 0. + * + * State tmp fields are guaranteed all NULL on a success return, because + * breakconstraintloop does that. After a failure return, any state that + * is known not to be part of a loop is marked with s->tmp == s; this allows + * us not to have to re-prove that fact on later calls. (This convention is + * workable because we already eliminated single-state loops.) + * + * Note that the found loop doesn't necessarily include the first state we + * are called on. Any loop reachable from that state will do. + * + * The maximum recursion depth here is one more than the length of the longest + * loop-free chain of constraint arcs, which is surely no more than the size + * of the NFA ... but that could still be enough to cause trouble. + */ +static int +findconstraintloop(struct nfa *nfa, struct state *s) +{ + struct arc *a; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return 1; /* to exit as quickly as possible */ + } + + if (s->tmp != NULL) + { + /* Already proven uninteresting? */ + if (s->tmp == s) + return 0; + /* Found a loop involving s */ + breakconstraintloop(nfa, s); + /* The tmp fields have been cleaned up by breakconstraintloop */ + return 1; + } + for (a = s->outs; a != NULL; a = a->outchain) + { + if (isconstraintarc(a)) + { + struct state *sto = a->to; + + assert(sto != s); + s->tmp = sto; + if (findconstraintloop(nfa, sto)) + return 1; + } + } + + /* + * If we get here, no constraint loop exists leading out from s. Mark it + * with s->tmp == s so we need not rediscover that fact again later. + */ + s->tmp = s; + return 0; +} + +/* + * breakconstraintloop - break a loop of constraint arcs + * + * sinitial is any one member state of the loop. Each loop member's tmp + * field links to its successor within the loop. (Note that this function + * will reset all the tmp fields to NULL.) + * + * We can break the loop by, for any one state S1 in the loop, cloning its + * loop successor state S2 (and possibly following states), and then moving + * all S1->S2 constraint arcs to point to the cloned S2. The cloned S2 should + * copy any non-constraint outarcs of S2. Constraint outarcs should be + * dropped if they point back to S1, else they need to be copied as arcs to + * similarly cloned states S3, S4, etc. In general, each cloned state copies + * non-constraint outarcs, drops constraint outarcs that would lead to itself + * or any earlier cloned state, and sends other constraint outarcs to newly + * cloned states. No cloned state will have any inarcs that aren't constraint + * arcs or do not lead from S1 or earlier-cloned states. It's okay to drop + * constraint back-arcs since they would not take us to any state we've not + * already been in; therefore, no new constraint loop is created. In this way + * we generate a modified NFA that can still represent every useful state + * sequence, but not sequences that represent state loops with no consumption + * of input data. Note that the set of cloned states will certainly include + * all of the loop member states other than S1, and it may also include + * non-loop states that are reachable from S2 via constraint arcs. This is + * important because there is no guarantee that findconstraintloop found a + * maximal loop (and searching for one would be NP-hard, so don't try). + * Frequently the "non-loop states" are actually part of a larger loop that + * we didn't notice, and indeed there may be several overlapping loops. + * This technique ensures convergence in such cases, while considering only + * the originally-found loop does not. + * + * If there is only one S1->S2 constraint arc, then that constraint is + * certainly satisfied when we enter any of the clone states. This means that + * in the common case where many of the constraint arcs are identically + * labeled, we can merge together clone states linked by a similarly-labeled + * constraint: if we can get to the first one we can certainly get to the + * second, so there's no need to distinguish. This greatly reduces the number + * of new states needed, so we preferentially break the given loop at a state + * pair where this is true. + * + * Furthermore, it's fairly common to find that a cloned successor state has + * no outarcs, especially if we're a bit aggressive about removing unnecessary + * outarcs. If that happens, then there is simply not any interesting state + * that can be reached through the predecessor's loop arcs, which means we can + * break the loop just by removing those loop arcs, with no new states added. + */ +static void +breakconstraintloop(struct nfa *nfa, struct state *sinitial) +{ + struct state *s; + struct state *shead; + struct state *stail; + struct state *sclone; + struct state *nexts; + struct arc *refarc; + struct arc *a; + struct arc *nexta; + + /* + * Start by identifying which loop step we want to break at. + * Preferentially this is one with only one constraint arc. (XXX are + * there any other secondary heuristics we want to use here?) Set refarc + * to point to the selected lone constraint arc, if there is one. + */ + refarc = NULL; + s = sinitial; + do + { + nexts = s->tmp; + assert(nexts != s); /* should not see any one-element loops */ + if (refarc == NULL) + { + int narcs = 0; + + for (a = s->outs; a != NULL; a = a->outchain) + { + if (a->to == nexts && isconstraintarc(a)) + { + refarc = a; + narcs++; + } + } + assert(narcs > 0); + if (narcs > 1) + refarc = NULL; /* multiple constraint arcs here, no good */ + } + s = nexts; + } while (s != sinitial); + + if (refarc) + { + /* break at the refarc */ + shead = refarc->from; + stail = refarc->to; + assert(stail == shead->tmp); + } + else + { + /* for lack of a better idea, break after sinitial */ + shead = sinitial; + stail = sinitial->tmp; + } + + /* + * Reset the tmp fields so that we can use them for local storage in + * clonesuccessorstates. (findconstraintloop won't mind, since it's just + * going to abandon its search anyway.) + */ + for (s = nfa->states; s != NULL; s = s->next) + s->tmp = NULL; + + /* + * Recursively build clone state(s) as needed. + */ + sclone = newstate(nfa); + if (sclone == NULL) + { + assert(NISERR()); + return; + } + + clonesuccessorstates(nfa, stail, sclone, shead, refarc, + NULL, NULL, nfa->nstates); + + if (NISERR()) + return; + + /* + * It's possible that sclone has no outarcs at all, in which case it's + * useless. (We don't try extremely hard to get rid of useless states + * here, but this is an easy and fairly common case.) + */ + if (sclone->nouts == 0) + { + freestate(nfa, sclone); + sclone = NULL; + } + + /* + * Move shead's constraint-loop arcs to point to sclone, or just drop them + * if we discovered we don't need sclone. + */ + for (a = shead->outs; a != NULL; a = nexta) + { + nexta = a->outchain; + if (a->to == stail && isconstraintarc(a)) + { + if (sclone) + cparc(nfa, a, shead, sclone); + freearc(nfa, a); + if (NISERR()) + break; + } + } +} + +/* + * clonesuccessorstates - create a tree of constraint-arc successor states + * + * ssource is the state to be cloned, and sclone is the state to copy its + * outarcs into. sclone's inarcs, if any, should already be set up. + * + * spredecessor is the original predecessor state that we are trying to build + * successors for (it may not be the immediate predecessor of ssource). + * refarc, if not NULL, is the original constraint arc that is known to have + * been traversed out of spredecessor to reach the successor(s). + * + * For each cloned successor state, we transiently create a "donemap" that is + * a boolean array showing which source states we've already visited for this + * clone state. This prevents infinite recursion as well as useless repeat + * visits to the same state subtree (which can add up fast, since typical NFAs + * have multiple redundant arc pathways). Each donemap is a char array + * indexed by state number. The donemaps are all of the same size "nstates", + * which is nfa->nstates as of the start of the recursion. This is enough to + * have entries for all pre-existing states, but *not* entries for clone + * states created during the recursion. That's okay since we have no need to + * mark those. + * + * curdonemap is NULL when recursing to a new sclone state, or sclone's + * donemap when we are recursing without having created a new state (which we + * do when we decide we can merge a successor state into the current clone + * state). outerdonemap is NULL at the top level and otherwise the parent + * clone state's donemap. + * + * The successor states we create and fill here form a strict tree structure, + * with each state having exactly one predecessor, except that the toplevel + * state has no inarcs as yet (breakconstraintloop will add its inarcs from + * spredecessor after we're done). Thus, we can examine sclone's inarcs back + * to the root, plus refarc if any, to identify the set of constraints already + * known valid at the current point. This allows us to avoid generating extra + * successor states. + */ +static void +clonesuccessorstates(struct nfa *nfa, + struct state *ssource, + struct state *sclone, + struct state *spredecessor, + struct arc *refarc, + char *curdonemap, + char *outerdonemap, + int nstates) +{ + char *donemap; + struct arc *a; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return; + } + + /* If this state hasn't already got a donemap, create one */ + donemap = curdonemap; + if (donemap == NULL) + { + donemap = (char *) MALLOC(nstates * sizeof(char)); + if (donemap == NULL) + { + NERR(REG_ESPACE); + return; + } + + if (outerdonemap != NULL) + { + /* + * Not at outermost recursion level, so copy the outer level's + * donemap; this ensures that we see states in process of being + * visited at outer levels, or already merged into predecessor + * states, as ones we shouldn't traverse back to. + */ + memcpy(donemap, outerdonemap, nstates * sizeof(char)); + } + else + { + /* At outermost level, only spredecessor is off-limits */ + memset(donemap, 0, nstates * sizeof(char)); + assert(spredecessor->no < nstates); + donemap[spredecessor->no] = 1; + } + } + + /* Mark ssource as visited in the donemap */ + assert(ssource->no < nstates); + assert(donemap[ssource->no] == 0); + donemap[ssource->no] = 1; + + /* + * We proceed by first cloning all of ssource's outarcs, creating new + * clone states as needed but not doing more with them than that. Then in + * a second pass, recurse to process the child clone states. This allows + * us to have only one child clone state per reachable source state, even + * when there are multiple outarcs leading to the same state. Also, when + * we do visit a child state, its set of inarcs is known exactly, which + * makes it safe to apply the constraint-is-already-checked optimization. + * Also, this ensures that we've merged all the states we can into the + * current clone before we recurse to any children, thus possibly saving + * them from making extra images of those states. + * + * While this function runs, child clone states of the current state are + * marked by setting their tmp fields to point to the original state they + * were cloned from. This makes it possible to detect multiple outarcs + * leading to the same state, and also makes it easy to distinguish clone + * states from original states (which will have tmp == NULL). + */ + for (a = ssource->outs; a != NULL && !NISERR(); a = a->outchain) + { + struct state *sto = a->to; + + /* + * We do not consider cloning successor states that have no constraint + * outarcs; just link to them as-is. They cannot be part of a + * constraint loop so there is no need to make copies. In particular, + * this rule keeps us from trying to clone the post state, which would + * be a bad idea. + */ + if (isconstraintarc(a) && hasconstraintout(sto)) + { + struct state *prevclone; + int canmerge; + struct arc *a2; + + /* + * Back-link constraint arcs must not be followed. Nor is there a + * need to revisit states previously merged into this clone. + */ + assert(sto->no < nstates); + if (donemap[sto->no] != 0) + continue; + + /* + * Check whether we already have a child clone state for this + * source state. + */ + prevclone = NULL; + for (a2 = sclone->outs; a2 != NULL; a2 = a2->outchain) + { + if (a2->to->tmp == sto) + { + prevclone = a2->to; + break; + } + } + + /* + * If this arc is labeled the same as refarc, or the same as any + * arc we must have traversed to get to sclone, then no additional + * constraints need to be met to get to sto, so we should just + * merge its outarcs into sclone. + */ + if (refarc && a->type == refarc->type && a->co == refarc->co) + canmerge = 1; + else + { + struct state *s; + + canmerge = 0; + for (s = sclone; s->ins; s = s->ins->from) + { + if (s->nins == 1 && + a->type == s->ins->type && a->co == s->ins->co) + { + canmerge = 1; + break; + } + } + } + + if (canmerge) + { + /* + * We can merge into sclone. If we previously made a child + * clone state, drop it; there's no need to visit it. (This + * can happen if ssource has multiple pathways to sto, and we + * only just now found one that is provably a no-op.) + */ + if (prevclone) + dropstate(nfa, prevclone); /* kills our outarc, too */ + + /* Recurse to merge sto's outarcs into sclone */ + clonesuccessorstates(nfa, + sto, + sclone, + spredecessor, + refarc, + donemap, + outerdonemap, + nstates); + /* sto should now be marked as previously visited */ + assert(NISERR() || donemap[sto->no] == 1); + } + else if (prevclone) + { + /* + * We already have a clone state for this successor, so just + * make another arc to it. + */ + cparc(nfa, a, sclone, prevclone); + } + else + { + /* + * We need to create a new successor clone state. + */ + struct state *stoclone; + + stoclone = newstate(nfa); + if (stoclone == NULL) + { + assert(NISERR()); + break; + } + /* Mark it as to what it's a clone of */ + stoclone->tmp = sto; + /* ... and add the outarc leading to it */ + cparc(nfa, a, sclone, stoclone); + } + } + else + { + /* + * Non-constraint outarcs just get copied to sclone, as do outarcs + * leading to states with no constraint outarc. + */ + cparc(nfa, a, sclone, sto); + } + } + + /* + * If we are at outer level for this clone state, recurse to all its child + * clone states, clearing their tmp fields as we go. (If we're not + * outermost for sclone, leave this to be done by the outer call level.) + * Note that if we have multiple outarcs leading to the same clone state, + * it will only be recursed-to once. + */ + if (curdonemap == NULL) + { + for (a = sclone->outs; a != NULL && !NISERR(); a = a->outchain) + { + struct state *stoclone = a->to; + struct state *sto = stoclone->tmp; + + if (sto != NULL) + { + stoclone->tmp = NULL; + clonesuccessorstates(nfa, + sto, + stoclone, + spredecessor, + refarc, + NULL, + donemap, + nstates); + } + } + + /* Don't forget to free sclone's donemap when done with it */ + FREE(donemap); + } +} + +/* + * cleanup - clean up NFA after optimizations + */ +static void +cleanup(struct nfa *nfa) +{ + struct state *s; + struct state *nexts; + int n; + + if (NISERR()) + return; + + /* clear out unreachable or dead-end states */ + /* use pre to mark reachable, then post to mark can-reach-post */ + markreachable(nfa, nfa->pre, (struct state *) NULL, nfa->pre); + markcanreach(nfa, nfa->post, nfa->pre, nfa->post); + for (s = nfa->states; s != NULL && !NISERR(); s = nexts) + { + nexts = s->next; + if (s->tmp != nfa->post && !s->flag) + dropstate(nfa, s); + } + assert(NISERR() || nfa->post->nins == 0 || nfa->post->tmp == nfa->post); + cleartraverse(nfa, nfa->pre); + assert(NISERR() || nfa->post->nins == 0 || nfa->post->tmp == NULL); + /* the nins==0 (final unreachable) case will be caught later */ + + /* renumber surviving states */ + n = 0; + for (s = nfa->states; s != NULL; s = s->next) + s->no = n++; + nfa->nstates = n; +} + +/* + * markreachable - recursive marking of reachable states + */ +static void +markreachable(struct nfa *nfa, + struct state *s, + struct state *okay, /* consider only states with this mark */ + struct state *mark) /* the value to mark with */ +{ + struct arc *a; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return; + } + + if (s->tmp != okay) + return; + s->tmp = mark; + + for (a = s->outs; a != NULL; a = a->outchain) + markreachable(nfa, a->to, okay, mark); +} + +/* + * markcanreach - recursive marking of states which can reach here + */ +static void +markcanreach(struct nfa *nfa, + struct state *s, + struct state *okay, /* consider only states with this mark */ + struct state *mark) /* the value to mark with */ +{ + struct arc *a; + + /* Since this is recursive, it could be driven to stack overflow */ + if (STACK_TOO_DEEP(nfa->v->re)) + { + NERR(REG_ETOOBIG); + return; + } + + if (s->tmp != okay) + return; + s->tmp = mark; + + for (a = s->ins; a != NULL; a = a->inchain) + markcanreach(nfa, a->from, okay, mark); +} + +/* + * analyze - ascertain potentially-useful facts about an optimized NFA + */ +static long /* re_info bits to be ORed in */ +analyze(struct nfa *nfa) +{ + struct arc *a; + struct arc *aa; + + if (NISERR()) + return 0; + + /* Detect whether NFA can't match anything */ + if (nfa->pre->outs == NULL) + return REG_UIMPOSSIBLE; + + /* Detect whether NFA matches all strings (possibly with length bounds) */ + checkmatchall(nfa); + + /* Detect whether NFA can possibly match a zero-length string */ + for (a = nfa->pre->outs; a != NULL; a = a->outchain) + for (aa = a->to->outs; aa != NULL; aa = aa->outchain) + if (aa->to == nfa->post) + return REG_UEMPTYMATCH; + return 0; +} + +/* + * checkmatchall - does the NFA represent no more than a string length test? + * + * If so, set nfa->minmatchall and nfa->maxmatchall correctly (they are -1 + * to begin with) and set the MATCHALL bit in nfa->flags. + * + * To succeed, we require all arcs to be PLAIN RAINBOW arcs, except for those + * for pseudocolors (i.e., BOS/BOL/EOS/EOL). We must be able to reach the + * post state via RAINBOW arcs, and if there are any loops in the graph, they + * must be loop-to-self arcs, ensuring that each loop iteration consumes + * exactly one character. (Longer loops are problematic because they create + * non-consecutive possible match lengths; we have no good way to represent + * that situation for lengths beyond the DUPINF limit.) + * + * Pseudocolor arcs complicate things a little. We know that they can only + * appear as pre-state outarcs (for BOS/BOL) or post-state inarcs (for + * EOS/EOL). There, they must exactly replicate the parallel RAINBOW arcs, + * e.g. if the pre state has one RAINBOW outarc to state 2, it must have BOS + * and BOL outarcs to state 2, and no others. Missing or extra pseudocolor + * arcs can occur, meaning that the NFA involves some constraint on the + * adjacent characters, which makes it not a matchall NFA. + */ +static void +checkmatchall(struct nfa *nfa) +{ + bool **haspaths; + struct state *s; + int i; + + /* + * If there are too many states, don't bother trying to detect matchall. + * This limit serves to bound the time and memory we could consume below. + * Note that even if the graph is all-RAINBOW, if there are significantly + * more than DUPINF states then it's likely that there are paths of length + * more than DUPINF, which would force us to fail anyhow. In practice, + * plausible ways of writing a matchall regex with maximum finite path + * length K tend not to have very many more than K states. + */ + if (nfa->nstates > DUPINF * 2) + return; + + /* + * First, scan all the states to verify that only RAINBOW arcs appear, + * plus pseudocolor arcs adjacent to the pre and post states. This lets + * us quickly eliminate most cases that aren't matchall NFAs. + */ + for (s = nfa->states; s != NULL; s = s->next) + { + struct arc *a; + + for (a = s->outs; a != NULL; a = a->outchain) + { + if (a->type != PLAIN) + return; /* any LACONs make it non-matchall */ + if (a->co != RAINBOW) + { + if (nfa->cm->cd[a->co].flags & PSEUDO) + { + /* + * Pseudocolor arc: verify it's in a valid place (this + * seems quite unlikely to fail, but let's be sure). + */ + if (s == nfa->pre && + (a->co == nfa->bos[0] || a->co == nfa->bos[1])) + /* okay BOS/BOL arc */ ; + else if (a->to == nfa->post && + (a->co == nfa->eos[0] || a->co == nfa->eos[1])) + /* okay EOS/EOL arc */ ; + else + return; /* unexpected pseudocolor arc */ + /* We'll check these arcs some more below. */ + } + else + return; /* any other color makes it non-matchall */ + } + } + /* Also, assert that the tmp fields are available for use. */ + assert(s->tmp == NULL); + } + + /* + * The next cheapest check we can make is to verify that the BOS/BOL + * outarcs of the pre state reach the same states as its RAINBOW outarcs. + * If they don't, the NFA expresses some constraints on the character + * before the matched string, making it non-matchall. Likewise, the + * EOS/EOL inarcs of the post state must match its RAINBOW inarcs. + */ + if (!check_out_colors_match(nfa->pre, RAINBOW, nfa->bos[0]) || + !check_out_colors_match(nfa->pre, RAINBOW, nfa->bos[1]) || + !check_in_colors_match(nfa->post, RAINBOW, nfa->eos[0]) || + !check_in_colors_match(nfa->post, RAINBOW, nfa->eos[1])) + return; + + /* + * Initialize an array of path-length arrays, in which + * checkmatchall_recurse will return per-state results. This lets us + * memo-ize the recursive search and avoid exponential time consumption. + */ + haspaths = (bool **) MALLOC(nfa->nstates * sizeof(bool *)); + if (haspaths == NULL) + return; /* fail quietly */ + memset(haspaths, 0, nfa->nstates * sizeof(bool *)); + + /* + * Recursively search the graph for all-RAINBOW paths to the "post" state, + * starting at the "pre" state, and computing the lengths of the paths. + * (Given the preceding checks, there should be at least one such path. + * However we could get back a false result anyway, in case there are + * multi-state loops, paths exceeding DUPINF+1 length, or non-algorithmic + * failures such as ENOMEM.) + */ + if (checkmatchall_recurse(nfa, nfa->pre, haspaths)) + { + /* The useful result is the path length array for the pre state */ + bool *haspath = haspaths[nfa->pre->no]; + int minmatch, + maxmatch, + morematch; + + assert(haspath != NULL); + + /* + * haspath[] now represents the set of possible path lengths; but we + * want to reduce that to a min and max value, because it doesn't seem + * worth complicating regexec.c to deal with nonconsecutive possible + * match lengths. Find min and max of first run of lengths, then + * verify there are no nonconsecutive lengths. + */ + for (minmatch = 0; minmatch <= DUPINF + 1; minmatch++) + { + if (haspath[minmatch]) + break; + } + assert(minmatch <= DUPINF + 1); /* else checkmatchall_recurse lied */ + for (maxmatch = minmatch; maxmatch < DUPINF + 1; maxmatch++) + { + if (!haspath[maxmatch + 1]) + break; + } + for (morematch = maxmatch + 1; morematch <= DUPINF + 1; morematch++) + { + if (haspath[morematch]) + { + haspath = NULL; /* fail, there are nonconsecutive lengths */ + break; + } + } + + if (haspath != NULL) + { + /* + * Success, so record the info. Here we have a fine point: the + * path length from the pre state includes the pre-to-initial + * transition, so it's one more than the actually matched string + * length. (We avoided counting the final-to-post transition + * within checkmatchall_recurse, but not this one.) This is why + * checkmatchall_recurse allows one more level of path length than + * might seem necessary. This decrement also takes care of + * converting checkmatchall_recurse's definition of "infinity" as + * "DUPINF+1" to our normal representation as "DUPINF". + */ + assert(minmatch > 0); /* else pre and post states were adjacent */ + nfa->minmatchall = minmatch - 1; + nfa->maxmatchall = maxmatch - 1; + nfa->flags |= MATCHALL; + } + } + + /* Clean up */ + for (i = 0; i < nfa->nstates; i++) + { + if (haspaths[i] != NULL) + FREE(haspaths[i]); + } + FREE(haspaths); +} + +/* + * checkmatchall_recurse - recursive search for checkmatchall + * + * s is the state to be examined in this recursion level. + * haspaths[] is an array of per-state exit path length arrays. + * + * We return true if the search was performed successfully, false if + * we had to fail because of multi-state loops or other internal reasons. + * (Because "dead" states that can't reach the post state have been + * eliminated, and we already verified that only RAINBOW and matching + * pseudocolor arcs exist, every state should have RAINBOW path(s) to + * the post state. Hence we take a false result from recursive calls + * as meaning that we'd better fail altogether, not just that that + * particular state can't reach the post state.) + * + * On success, we store a malloc'd result array in haspaths[s->no], + * showing the possible path lengths from s to the post state. + * Each state's haspath[] array is of length DUPINF+2. The entries from + * k = 0 to DUPINF are true if there is an all-RAINBOW path of length k + * from this state to the string end. haspath[DUPINF+1] is true if all + * path lengths >= DUPINF+1 are possible. (Situations that cannot be + * represented under these rules cause failure.) + * + * checkmatchall is responsible for eventually freeing the haspath[] arrays. + */ +static bool +checkmatchall_recurse(struct nfa *nfa, struct state *s, bool **haspaths) +{ + bool result = false; + bool foundloop = false; + bool *haspath; + struct arc *a; + + /* + * Since this is recursive, it could be driven to stack overflow. But we + * need not treat that as a hard failure; just deem the NFA non-matchall. + */ + if (STACK_TOO_DEEP(nfa->v->re)) + return false; + + /* In case the search takes a long time, check for cancel */ + if (CANCEL_REQUESTED(nfa->v->re)) + { + NERR(REG_CANCEL); + return false; + } + + /* Create a haspath array for this state */ + haspath = (bool *) MALLOC((DUPINF + 2) * sizeof(bool)); + if (haspath == NULL) + return false; /* again, treat as non-matchall */ + memset(haspath, 0, (DUPINF + 2) * sizeof(bool)); + + /* Mark this state as being visited */ + assert(s->tmp == NULL); + s->tmp = s; + + for (a = s->outs; a != NULL; a = a->outchain) + { + if (a->co != RAINBOW) + continue; /* ignore pseudocolor arcs */ + if (a->to == nfa->post) + { + /* We found an all-RAINBOW path to the post state */ + result = true; + + /* + * Mark this state as being zero steps away from the string end + * (the transition to the post state isn't counted). + */ + haspath[0] = true; + } + else if (a->to == s) + { + /* We found a cycle of length 1, which we'll deal with below. */ + foundloop = true; + } + else if (a->to->tmp != NULL) + { + /* It's busy, so we found a cycle of length > 1, so fail. */ + result = false; + break; + } + else + { + /* Consider paths forward through this to-state. */ + bool *nexthaspath; + int i; + + /* If to-state was not already visited, recurse */ + if (haspaths[a->to->no] == NULL) + { + result = checkmatchall_recurse(nfa, a->to, haspaths); + /* Fail if any recursive path fails */ + if (!result) + break; + } + else + { + /* The previous visit must have found path(s) to the end */ + result = true; + } + assert(a->to->tmp == NULL); + nexthaspath = haspaths[a->to->no]; + assert(nexthaspath != NULL); + + /* + * Now, for every path of length i from a->to to the string end, + * there is a path of length i + 1 from s to the string end. + */ + if (nexthaspath[DUPINF] != nexthaspath[DUPINF + 1]) + { + /* + * a->to has a path of length exactly DUPINF, but not longer; + * or it has paths of all lengths > DUPINF but not one of + * exactly that length. In either case, we cannot represent + * the possible path lengths from s correctly, so fail. + */ + result = false; + break; + } + /* Merge knowledge of these path lengths into what we have */ + for (i = 0; i < DUPINF; i++) + haspath[i + 1] |= nexthaspath[i]; + /* Infinity + 1 is still infinity */ + haspath[DUPINF + 1] |= nexthaspath[DUPINF + 1]; + } + } + + if (result && foundloop) + { + /* + * If there is a length-1 loop at this state, then find the shortest + * known path length to the end. The loop means that every larger + * path length is possible, too. (It doesn't matter whether any of + * the longer lengths were already known possible.) + */ + int i; + + for (i = 0; i <= DUPINF; i++) + { + if (haspath[i]) + break; + } + for (i++; i <= DUPINF + 1; i++) + haspath[i] = true; + } + + /* Report out the completed path length map */ + assert(s->no < nfa->nstates); + assert(haspaths[s->no] == NULL); + haspaths[s->no] = haspath; + + /* Mark state no longer busy */ + s->tmp = NULL; + + return result; +} + +/* + * check_out_colors_match - subroutine for checkmatchall + * + * Check whether the set of states reachable from s by arcs of color co1 + * is equivalent to the set reachable by arcs of color co2. + * checkmatchall already verified that all of the NFA's arcs are PLAIN, + * so we need not examine arc types here. + */ +static bool +check_out_colors_match(struct state *s, color co1, color co2) +{ + bool result = true; + struct arc *a; + + /* + * To do this in linear time, we assume that the NFA contains no duplicate + * arcs. Run through the out-arcs, marking states reachable by arcs of + * color co1. Run through again, un-marking states reachable by arcs of + * color co2; if we see a not-marked state, we know this co2 arc is + * unmatched. Then run through again, checking for still-marked states, + * and in any case leaving all the tmp fields reset to NULL. + */ + for (a = s->outs; a != NULL; a = a->outchain) + { + if (a->co == co1) + { + assert(a->to->tmp == NULL); + a->to->tmp = a->to; + } + } + for (a = s->outs; a != NULL; a = a->outchain) + { + if (a->co == co2) + { + if (a->to->tmp != NULL) + a->to->tmp = NULL; + else + result = false; /* unmatched co2 arc */ + } + } + for (a = s->outs; a != NULL; a = a->outchain) + { + if (a->co == co1) + { + if (a->to->tmp != NULL) + { + result = false; /* unmatched co1 arc */ + a->to->tmp = NULL; + } + } + } + return result; +} + +/* + * check_in_colors_match - subroutine for checkmatchall + * + * Check whether the set of states that can reach s by arcs of color co1 + * is equivalent to the set that can reach s by arcs of color co2. + * checkmatchall already verified that all of the NFA's arcs are PLAIN, + * so we need not examine arc types here. + */ +static bool +check_in_colors_match(struct state *s, color co1, color co2) +{ + bool result = true; + struct arc *a; + + /* + * Identical algorithm to check_out_colors_match, except examine the + * from-states of s' inarcs. + */ + for (a = s->ins; a != NULL; a = a->inchain) + { + if (a->co == co1) + { + assert(a->from->tmp == NULL); + a->from->tmp = a->from; + } + } + for (a = s->ins; a != NULL; a = a->inchain) + { + if (a->co == co2) + { + if (a->from->tmp != NULL) + a->from->tmp = NULL; + else + result = false; /* unmatched co2 arc */ + } + } + for (a = s->ins; a != NULL; a = a->inchain) + { + if (a->co == co1) + { + if (a->from->tmp != NULL) + { + result = false; /* unmatched co1 arc */ + a->from->tmp = NULL; + } + } + } + return result; +} + +/* + * compact - construct the compact representation of an NFA + */ +static void +compact(struct nfa *nfa, + struct cnfa *cnfa) +{ + struct state *s; + struct arc *a; + size_t nstates; + size_t narcs; + struct carc *ca; + struct carc *first; + + assert(!NISERR()); + + nstates = 0; + narcs = 0; + for (s = nfa->states; s != NULL; s = s->next) + { + nstates++; + narcs += s->nouts + 1; /* need one extra for endmarker */ + } + + cnfa->stflags = (char *) MALLOC(nstates * sizeof(char)); + cnfa->states = (struct carc **) MALLOC(nstates * sizeof(struct carc *)); + cnfa->arcs = (struct carc *) MALLOC(narcs * sizeof(struct carc)); + if (cnfa->stflags == NULL || cnfa->states == NULL || cnfa->arcs == NULL) + { + if (cnfa->stflags != NULL) + FREE(cnfa->stflags); + if (cnfa->states != NULL) + FREE(cnfa->states); + if (cnfa->arcs != NULL) + FREE(cnfa->arcs); + NERR(REG_ESPACE); + return; + } + cnfa->nstates = nstates; + cnfa->pre = nfa->pre->no; + cnfa->post = nfa->post->no; + cnfa->bos[0] = nfa->bos[0]; + cnfa->bos[1] = nfa->bos[1]; + cnfa->eos[0] = nfa->eos[0]; + cnfa->eos[1] = nfa->eos[1]; + cnfa->ncolors = maxcolor(nfa->cm) + 1; + cnfa->flags = nfa->flags; + cnfa->minmatchall = nfa->minmatchall; + cnfa->maxmatchall = nfa->maxmatchall; + + ca = cnfa->arcs; + for (s = nfa->states; s != NULL; s = s->next) + { + assert((size_t) s->no < nstates); + cnfa->stflags[s->no] = 0; + cnfa->states[s->no] = ca; + first = ca; + for (a = s->outs; a != NULL; a = a->outchain) + switch (a->type) + { + case PLAIN: + ca->co = a->co; + ca->to = a->to->no; + ca++; + break; + case LACON: + assert(s->no != cnfa->pre); + assert(a->co >= 0); + ca->co = (color) (cnfa->ncolors + a->co); + ca->to = a->to->no; + ca++; + cnfa->flags |= HASLACONS; + break; + default: + NERR(REG_ASSERT); + return; + } + carcsort(first, ca - first); + ca->co = COLORLESS; + ca->to = 0; + ca++; + } + assert(ca == &cnfa->arcs[narcs]); + assert(cnfa->nstates != 0); + + /* mark no-progress states */ + for (a = nfa->pre->outs; a != NULL; a = a->outchain) + cnfa->stflags[a->to->no] = CNFA_NOPROGRESS; + cnfa->stflags[nfa->pre->no] = CNFA_NOPROGRESS; +} + +/* + * carcsort - sort compacted-NFA arcs by color + */ +static void +carcsort(struct carc *first, size_t n) +{ + if (n > 1) + qsort(first, n, sizeof(struct carc), carc_cmp); +} + +static int +carc_cmp(const void *a, const void *b) +{ + const struct carc *aa = (const struct carc *) a; + const struct carc *bb = (const struct carc *) b; + + if (aa->co < bb->co) + return -1; + if (aa->co > bb->co) + return +1; + if (aa->to < bb->to) + return -1; + if (aa->to > bb->to) + return +1; + /* This is unreached, since there should be no duplicate arcs now: */ + return 0; +} + +/* + * freecnfa - free a compacted NFA + */ +static void +freecnfa(struct cnfa *cnfa) +{ + assert(!NULLCNFA(*cnfa)); /* not empty already */ + FREE(cnfa->stflags); + FREE(cnfa->states); + FREE(cnfa->arcs); + ZAPCNFA(*cnfa); +} + +/* + * dumpnfa - dump an NFA in human-readable form + */ +static void +dumpnfa(struct nfa *nfa, + FILE *f) +{ +#ifdef REG_DEBUG + struct state *s; + int nstates = 0; + int narcs = 0; + + fprintf(f, "pre %d, post %d", nfa->pre->no, nfa->post->no); + if (nfa->bos[0] != COLORLESS) + fprintf(f, ", bos [%ld]", (long) nfa->bos[0]); + if (nfa->bos[1] != COLORLESS) + fprintf(f, ", bol [%ld]", (long) nfa->bos[1]); + if (nfa->eos[0] != COLORLESS) + fprintf(f, ", eos [%ld]", (long) nfa->eos[0]); + if (nfa->eos[1] != COLORLESS) + fprintf(f, ", eol [%ld]", (long) nfa->eos[1]); + if (nfa->flags & HASLACONS) + fprintf(f, ", haslacons"); + if (nfa->flags & MATCHALL) + { + fprintf(f, ", minmatchall %d", nfa->minmatchall); + if (nfa->maxmatchall == DUPINF) + fprintf(f, ", maxmatchall inf"); + else + fprintf(f, ", maxmatchall %d", nfa->maxmatchall); + } + fprintf(f, "\n"); + for (s = nfa->states; s != NULL; s = s->next) + { + dumpstate(s, f); + nstates++; + narcs += s->nouts; + } + fprintf(f, "total of %d states, %d arcs\n", nstates, narcs); + if (nfa->parent == NULL) + dumpcolors(nfa->cm, f); + fflush(f); +#endif +} + +#ifdef REG_DEBUG /* subordinates of dumpnfa */ + +/* + * dumpstate - dump an NFA state in human-readable form + */ +static void +dumpstate(struct state *s, + FILE *f) +{ + struct arc *a; + + fprintf(f, "%d%s%c", s->no, (s->tmp != NULL) ? "T" : "", + (s->flag) ? s->flag : '.'); + if (s->prev != NULL && s->prev->next != s) + fprintf(f, "\tstate chain bad\n"); + if (s->nouts == 0) + fprintf(f, "\tno out arcs\n"); + else + dumparcs(s, f); + for (a = s->ins; a != NULL; a = a->inchain) + { + if (a->to != s) + fprintf(f, "\tlink from %d to %d on %d's in-chain\n", + a->from->no, a->to->no, s->no); + } + fflush(f); +} + +/* + * dumparcs - dump out-arcs in human-readable form + */ +static void +dumparcs(struct state *s, + FILE *f) +{ + int pos; + struct arc *a; + + /* printing oldest arcs first is usually clearer */ + a = s->outs; + assert(a != NULL); + while (a->outchain != NULL) + a = a->outchain; + pos = 1; + do + { + dumparc(a, s, f); + if (pos == 5) + { + fprintf(f, "\n"); + pos = 1; + } + else + pos++; + a = a->outchainRev; + } while (a != NULL); + if (pos != 1) + fprintf(f, "\n"); +} + +/* + * dumparc - dump one outarc in readable form, including prefixing tab + */ +static void +dumparc(struct arc *a, + struct state *s, + FILE *f) +{ + struct arc *aa; + + fprintf(f, "\t"); + switch (a->type) + { + case PLAIN: + if (a->co == RAINBOW) + fprintf(f, "[*]"); + else + fprintf(f, "[%ld]", (long) a->co); + break; + case AHEAD: + if (a->co == RAINBOW) + fprintf(f, ">*>"); + else + fprintf(f, ">%ld>", (long) a->co); + break; + case BEHIND: + if (a->co == RAINBOW) + fprintf(f, "<*<"); + else + fprintf(f, "<%ld<", (long) a->co); + break; + case LACON: + fprintf(f, ":%ld:", (long) a->co); + break; + case '^': + case '$': + fprintf(f, "%c%d", a->type, (int) a->co); + break; + case EMPTY: + break; + default: + fprintf(f, "0x%x/0%lo", a->type, (long) a->co); + break; + } + if (a->from != s) + fprintf(f, "?%d?", a->from->no); + for (aa = a->from->outs; aa != NULL; aa = aa->outchain) + if (aa == a) + break; /* NOTE BREAK OUT */ + if (aa == NULL) + fprintf(f, "?!?"); /* missing from out-chain */ + fprintf(f, "->"); + if (a->to == NULL) + { + fprintf(f, "NULL"); + return; + } + fprintf(f, "%d", a->to->no); + for (aa = a->to->ins; aa != NULL; aa = aa->inchain) + if (aa == a) + break; /* NOTE BREAK OUT */ + if (aa == NULL) + fprintf(f, "?!?"); /* missing from in-chain */ +} +#endif /* REG_DEBUG */ + +/* + * dumpcnfa - dump a compacted NFA in human-readable form + */ +#ifdef REG_DEBUG +static void +dumpcnfa(struct cnfa *cnfa, + FILE *f) +{ + int st; + + fprintf(f, "pre %d, post %d", cnfa->pre, cnfa->post); + if (cnfa->bos[0] != COLORLESS) + fprintf(f, ", bos [%ld]", (long) cnfa->bos[0]); + if (cnfa->bos[1] != COLORLESS) + fprintf(f, ", bol [%ld]", (long) cnfa->bos[1]); + if (cnfa->eos[0] != COLORLESS) + fprintf(f, ", eos [%ld]", (long) cnfa->eos[0]); + if (cnfa->eos[1] != COLORLESS) + fprintf(f, ", eol [%ld]", (long) cnfa->eos[1]); + if (cnfa->flags & HASLACONS) + fprintf(f, ", haslacons"); + if (cnfa->flags & MATCHALL) + { + fprintf(f, ", minmatchall %d", cnfa->minmatchall); + if (cnfa->maxmatchall == DUPINF) + fprintf(f, ", maxmatchall inf"); + else + fprintf(f, ", maxmatchall %d", cnfa->maxmatchall); + } + fprintf(f, "\n"); + for (st = 0; st < cnfa->nstates; st++) + dumpcstate(st, cnfa, f); + fflush(f); +} +#endif + +#ifdef REG_DEBUG /* subordinates of dumpcnfa */ + +/* + * dumpcstate - dump a compacted-NFA state in human-readable form + */ +static void +dumpcstate(int st, + struct cnfa *cnfa, + FILE *f) +{ + struct carc *ca; + int pos; + + fprintf(f, "%d%s", st, (cnfa->stflags[st] & CNFA_NOPROGRESS) ? ":" : "."); + pos = 1; + for (ca = cnfa->states[st]; ca->co != COLORLESS; ca++) + { + if (ca->co == RAINBOW) + fprintf(f, "\t[*]->%d", ca->to); + else if (ca->co < cnfa->ncolors) + fprintf(f, "\t[%ld]->%d", (long) ca->co, ca->to); + else + fprintf(f, "\t:%ld:->%d", (long) (ca->co - cnfa->ncolors), ca->to); + if (pos == 5) + { + fprintf(f, "\n"); + pos = 1; + } + else + pos++; + } + if (ca == cnfa->states[st] || pos != 1) + fprintf(f, "\n"); + fflush(f); +} + +#endif /* REG_DEBUG */ |