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author | William Joye <wjoye@cfa.harvard.edu> | 2017-09-22 18:51:12 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2017-09-22 18:51:12 (GMT) |
commit | 3fa8e6dc88e8041b6cb88d1b1e9c05676d3346b7 (patch) | |
tree | 69afbb41089c8358615879f7cd3c4cf7997f4c7e /tcl8.6/generic/regc_nfa.c | |
parent | a0e17db23c0fd7c771c0afce8cce350c98f90b02 (diff) | |
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update to tcl/tk 8.6.7
Diffstat (limited to 'tcl8.6/generic/regc_nfa.c')
-rw-r--r-- | tcl8.6/generic/regc_nfa.c | 3213 |
1 files changed, 0 insertions, 3213 deletions
diff --git a/tcl8.6/generic/regc_nfa.c b/tcl8.6/generic/regc_nfa.c deleted file mode 100644 index 088c6c0..0000000 --- a/tcl8.6/generic/regc_nfa.c +++ /dev/null @@ -1,3213 +0,0 @@ -/* - * 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. - * - * 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)) -#define STACK_TOO_DEEP(x) (0) -#define CANCEL_REQUESTED(x) (0) -#define REG_CANCEL 777 - -/* - - newnfa - set up an NFA - ^ static struct nfa *newnfa(struct vars *, struct colormap *, struct 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; - } - - nfa->states = NULL; - nfa->slast = NULL; - nfa->free = NULL; - nfa->nstates = 0; - nfa->cm = cm; - nfa->v = v; - nfa->bos[0] = nfa->bos[1] = COLORLESS; - nfa->eos[0] = nfa->eos[1] = COLORLESS; - nfa->parent = parent; /* Precedes newfstate so parent is valid. */ - 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 *); - */ -static void -freenfa( - struct nfa *nfa) -{ - struct state *s; - - while ((s = nfa->states) != NULL) { - s->nins = s->nouts = 0; /* don't worry about arcs */ - freestate(nfa, s); - } - while ((s = nfa->free) != NULL) { - nfa->free = s->next; - destroystate(nfa, s); - } - - nfa->slast = NULL; - nfa->nstates = -1; - nfa->pre = NULL; - nfa->post = NULL; - FREE(nfa); -} - -/* - - newstate - allocate an NFA state, with zero flag value - ^ static struct state *newstate(struct nfa *); - */ -static struct state * /* NULL on error */ -newstate( - struct nfa *nfa) -{ - struct state *s; - - if (nfa->free != NULL) { - s = nfa->free; - nfa->free = s->next; - } else { - if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE) { - NERR(REG_ETOOBIG); - return NULL; - } - s = (struct state *) MALLOC(sizeof(struct state)); - if (s == NULL) { - NERR(REG_ESPACE); - return NULL; - } - nfa->v->spaceused += sizeof(struct state); - s->oas.next = NULL; - s->free = NULL; - s->noas = 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 *newfstate(struct nfa *, int flag); - */ -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 *, struct state *); - */ -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 *, struct state *); - */ -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->free; /* don't delete it, put it on the free list */ - nfa->free = s; -} - -/* - - destroystate - really get rid of an already-freed state - ^ static void destroystate(struct nfa *, struct state *); - */ -static void -destroystate( - struct nfa *nfa, - struct state *s) -{ - struct arcbatch *ab; - struct arcbatch *abnext; - - assert(s->no == FREESTATE); - for (ab=s->oas.next ; ab!=NULL ; ab=abnext) { - abnext = ab->next; - FREE(ab); - nfa->v->spaceused -= sizeof(struct arcbatch); - } - s->ins = NULL; - s->outs = NULL; - s->next = NULL; - FREE(s); - nfa->v->spaceused -= sizeof(struct state); -} - -/* - - newarc - set up a new arc within an NFA - ^ static void newarc(struct nfa *, int, pcolor, struct state *, - ^ struct state *); - */ -/* - * This function checks to make sure that no duplicate arcs are created. - * In general we never want duplicates. - */ -static void -newarc( - struct nfa *nfa, - int t, - pcolor co, - struct state *from, - struct state *to) -{ - struct arc *a; - - assert(from != NULL && to != NULL); - - /* 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, - pcolor co, - struct state * from, - struct state * to) -{ - struct arc *a; - - /* the arc is physically allocated within its from-state */ - a = allocarc(nfa, from); - if (NISERR()) { - return; - } - assert(a != NULL); - - a->type = t; - a->co = (color) 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 out-arc within a state - ^ static struct arc *allocarc(struct nfa *, struct state *); - */ -static struct arc * /* NULL for failure */ -allocarc( - struct nfa *nfa, - struct state *s) -{ - struct arc *a; - - /* - * Shortcut - */ - - if (s->free == NULL && s->noas < ABSIZE) { - a = &s->oas.a[s->noas]; - s->noas++; - return a; - } - - /* - * if none at hand, get more - */ - - if (s->free == NULL) { - struct arcbatch *newAb; - int i; - - if (nfa->v->spaceused >= REG_MAX_COMPILE_SPACE) { - NERR(REG_ETOOBIG); - return NULL; - } - newAb = (struct arcbatch *) MALLOC(sizeof(struct arcbatch)); - if (newAb == NULL) { - NERR(REG_ESPACE); - return NULL; - } - nfa->v->spaceused += sizeof(struct arcbatch); - newAb->next = s->oas.next; - s->oas.next = newAb; - - for (i=0 ; i<ABSIZE ; i++) { - newAb->a[i].type = 0; - newAb->a[i].freechain = &newAb->a[i+1]; - } - newAb->a[ABSIZE-1].freechain = NULL; - s->free = &newAb->a[0]; - } - assert(s->free != NULL); - - a = s->free; - s->free = a->freechain; - return a; -} - -/* - - freearc - free an arc - ^ static void freearc(struct nfa *, struct 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 from-state'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 = from->free; - from->free = victim; -} - -/* - * changearctarget - flip an arc to have a different to state - * - * Caller must have verified that there is no pre-existing duplicate arc. - * - * Note that because we store arcs in their from state, we can't easily have - * a similar changearcsource function. - */ -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 *); - */ -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 *, int, pcolor); - */ -static struct arc * -findarc( - struct state *s, - int type, - pcolor 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 *, struct arc *, struct state *, - ^ struct state *); - */ -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. - * - ^ static void moveins(struct nfa *, struct state *, struct state *); - */ -static void -moveins( - struct nfa *nfa, - struct state *oldState, - struct state *newState) -{ - assert(oldState != newState); - - 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 - ^ static VOID copyins(struct nfa *, struct state *, struct state *, int); - */ -static void -copyins( - struct nfa *nfa, - struct state *oldState, - struct state *newState) -{ - assert(oldState != newState); - - 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); - } - } -} - -/* - * 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 - ^ static void moveouts(struct nfa *, struct state *, struct state *); - */ -static void -moveouts( - struct nfa *nfa, - struct state *oldState, - struct state *newState) -{ - assert(oldState != newState); - - 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 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); - freearc(nfa, a); - 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; - createarc(nfa, a->type, a->co, newState, a->to); - freearc(nfa, a); - } - } - - assert(oldState->nouts == 0); - assert(oldState->outs == NULL); -} - -/* - - copyouts - copy out arcs of a state to another state - ^ static VOID copyouts(struct nfa *, struct state *, struct state *, int); - */ -static void -copyouts( - struct nfa *nfa, - struct state *oldState, - struct state *newState) -{ - assert(oldState != newState); - - 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); - } - } -} - -/* - - cloneouts - copy out arcs of a state to another state pair, modifying type - ^ static void cloneouts(struct nfa *, struct state *, struct state *, - ^ struct state *, int); - */ -static void -cloneouts( - struct nfa *nfa, - struct state *old, - struct state *from, - struct state *to, - int type) -{ - struct arc *a; - - assert(old != from); - - for (a=old->outs ; a!=NULL ; a=a->outchain) { - 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 *, struct state *, struct state *); - */ -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); - 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 *, struct state *, struct state *); - */ -static void -deltraverse( - struct nfa *nfa, - struct state *leftend, - struct state *s) -{ - struct arc *a; - struct state *to; - - 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); - 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 *, struct state *, struct state *, - ^ struct state *, struct state *); - */ -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, 0); - /* done, except for clearing out the tmp pointers */ - - stop->tmp = NULL; - cleartraverse(nfa, start); -} - -/* - - duptraverse - recursive heart of dupnfa - ^ static void duptraverse(struct nfa *, struct state *, struct state *); - */ -static void -duptraverse( - struct nfa *nfa, - struct state *s, - struct state *stmp, /* s's duplicate, or NULL */ - int depth) -{ - struct arc *a; - - if (s->tmp != NULL) { - return; /* already done */ - } - - s->tmp = (stmp == NULL) ? newstate(nfa) : stmp; - if (s->tmp == NULL) { - assert(NISERR()); - return; - } - - /* - * Arbitrary depth limit. Needs tuning, but this value is sufficient to - * make all normal tests (not reg-33.14) pass. - */ -#ifndef DUPTRAVERSE_MAX_DEPTH -#define DUPTRAVERSE_MAX_DEPTH 15000 -#endif - - if (depth++ > DUPTRAVERSE_MAX_DEPTH) { - NERR(REG_ESPACE); - } - - for (a=s->outs ; a!=NULL && !NISERR() ; a=a->outchain) { - duptraverse(nfa, a->to, NULL, depth); - if (NISERR()) { - break; - } - assert(a->to->tmp != NULL); - cparc(nfa, a, s->tmp, a->to->tmp); - } -} - -/* - - cleartraverse - recursive cleanup for algorithms that leave tmp ptrs set - ^ static void cleartraverse(struct nfa *, struct state *); - */ -static void -cleartraverse( - struct nfa *nfa, - struct state *s) -{ - struct arc *a; - - if (s->tmp == NULL) { - return; - } - s->tmp = NULL; - - for (a=s->outs ; a!=NULL ; a=a->outchain) { - cleartraverse(nfa, a->to); - } -} - -/* - - specialcolors - fill in special colors for an NFA - ^ static void specialcolors(struct 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 - ^ static long optimize(struct nfa *, FILE *); - */ - - /* - * 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 */ -{ - int verbose = (f != NULL) ? 1 : 0; - - if (verbose) { - fprintf(f, "\ninitial cleanup:\n"); - } - cleanup(nfa); /* may simplify situation */ - if (verbose) { - dumpnfa(nfa, f); - } - if (verbose) { - fprintf(f, "\nempties:\n"); - } - fixempties(nfa, f); /* get rid of EMPTY arcs */ - if (verbose) { - fprintf(f, "\nconstraints:\n"); - } - fixconstraintloops(nfa, f); /* get rid of constraint loops */ - pullback(nfa, f); /* pull back constraints backward */ - pushfwd(nfa, f); /* push fwd constraints forward */ - if (verbose) { - fprintf(f, "\nfinal cleanup:\n"); - } - 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 *, FILE *); - */ -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; - } - } - assert(nexta == NULL || s->no != FREESTATE); - } - /* 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 *, struct arc *); - */ -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(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; - 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 *, FILE *); - */ -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 *, struct arc *); - */ -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(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; - 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 - ^ static int combine(struct arc *, struct arc *); - */ -static int -combine( - 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; - } - return INCOMPATIBLE; - break; - case CA('^', '^'): /* collision, similar constraints */ - case CA('$', '$'): - case CA(AHEAD, AHEAD): - case CA(BEHIND, BEHIND): - if (con->co == a->co) { /* true duplication */ - return SATISFIED; - } - 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 *, FILE *); - */ -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; - /* 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; - } - - /* - * 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, and in practice will be less than that. - ^ static struct state *emptyreachable(struct state *, struct state *); - */ -static struct state * -emptyreachable( - struct nfa *nfa, - struct state *s, - struct state *lastfound, - struct arc **inarcsorig) -{ - struct arc *a; - - 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, and in practice will be a lot less than that. - */ -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 *); - */ -static void -cleanup( - struct nfa *nfa) -{ - struct state *s; - struct state *nexts; - int n; - - /* - * Clear out unreachable or dead-end states. Use pre to mark reachable, - * then post to mark can-reach-post. - */ - - markreachable(nfa, nfa->pre, NULL, nfa->pre); - markcanreach(nfa, nfa->post, nfa->pre, nfa->post); - for (s = nfa->states; s != NULL; s = nexts) { - nexts = s->next; - if (s->tmp != nfa->post && !s->flag) { - dropstate(nfa, s); - } - } - assert(nfa->post->nins == 0 || nfa->post->tmp == nfa->post); - cleartraverse(nfa, nfa->pre); - assert(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 *, struct state *, struct state *, - ^ struct state *); - */ -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; - - 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 *, struct state *, struct state *, - ^ struct state *); - */ -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; - - 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 analyze(struct nfa *); - */ -static long /* re_info bits to be ORed in */ -analyze( - struct nfa *nfa) -{ - struct arc *a; - struct arc *aa; - - if (nfa->pre->outs == NULL) { - return REG_UIMPOSSIBLE; - } - 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; -} - -/* - - compact - construct the compact representation of an NFA - ^ static void compact(struct nfa *, struct cnfa *); - */ -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 = 0; - - 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); - ca->co = (color) (cnfa->ncolors + a->co); - ca->to = a->to->no; - ca++; - cnfa->flags |= HASLACONS; - break; - default: - NERR(REG_ASSERT); - break; - } - } - 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 *, struct carc *); - */ -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; - } - return 0; -} - -/* - - freecnfa - free a compacted NFA - ^ static void freecnfa(struct cnfa *); - */ -static void -freecnfa( - struct cnfa *cnfa) -{ - assert(cnfa->nstates != 0); /* not empty already */ - cnfa->nstates = 0; - FREE(cnfa->stflags); - FREE(cnfa->states); - FREE(cnfa->arcs); -} - -/* - - dumpnfa - dump an NFA in human-readable form - ^ static void dumpnfa(struct nfa *, FILE *); - */ -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]); - } - 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 */ -/* - ^ #ifdef REG_DEBUG - */ - -/* - - dumpstate - dump an NFA state in human-readable form - ^ static void dumpstate(struct state *, FILE *); - */ -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); - } - fflush(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); - } - } -} - -/* - - dumparcs - dump out-arcs in human-readable form - ^ static void dumparcs(struct state *, FILE *); - */ -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 *, struct state *, FILE *); - */ -static void -dumparc( - struct arc *a, - struct state *s, - FILE *f) -{ - struct arc *aa; - struct arcbatch *ab; - - fprintf(f, "\t"); - switch (a->type) { - case PLAIN: - fprintf(f, "[%ld]", (long) a->co); - break; - case AHEAD: - fprintf(f, ">%ld>", (long) a->co); - break; - case BEHIND: - 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 (ab = &a->from->oas; ab != NULL; ab = ab->next) { - for (aa = &ab->a[0]; aa < &ab->a[ABSIZE]; aa++) { - if (aa == a) { - break; /* NOTE BREAK OUT */ - } - } - if (aa < &ab->a[ABSIZE]) { /* propagate break */ - break; /* NOTE BREAK OUT */ - } - } - if (ab == NULL) { - fprintf(f, "?!?"); /* not in allocated space */ - } - 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 - */ -#endif /* ifdef REG_DEBUG */ - -/* - - dumpcnfa - dump a compacted NFA in human-readable form - ^ static void dumpcnfa(struct cnfa *, FILE *); - */ -static void -dumpcnfa( - struct cnfa *cnfa, - FILE *f) -{ -#ifdef REG_DEBUG - 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"); - } - fprintf(f, "\n"); - for (st = 0; st < cnfa->nstates; st++) { - dumpcstate(st, cnfa, f); - } - fflush(f); -#endif -} - -#ifdef REG_DEBUG /* subordinates of dumpcnfa */ -/* - ^ #ifdef REG_DEBUG - */ - -/* - - dumpcstate - dump a compacted-NFA state in human-readable form - ^ static void dumpcstate(int, struct cnfa *, FILE *); - */ -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 < 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 - */ -#endif /* ifdef REG_DEBUG */ - -/* - * Local Variables: - * mode: c - * c-basic-offset: 4 - * fill-column: 78 - * End: - */ |