+/*
+ * 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.
+ *
+ * $Header$
+ *
+ *
+ * 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)
+ 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->post = newfstate(nfa, '@'); /* number 0 */
+ nfa->pre = newfstate(nfa, '>'); /* number 1 */
+ nfa->parent = parent;
+
+ 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 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 * /* NULL on error */
+newstate(struct nfa * nfa)
+{
+ struct state *s;
+
+ if (nfa->free != NULL)
+ {
+ s = nfa->free;
+ nfa->free = s->next;
+ }
+ else
+ {
+ s = (struct state *) MALLOC(sizeof(struct state));
+ if (s == NULL)
+ {
+ NERR(REG_ESPACE);
+ return NULL;
+ }
+ 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 * /* 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->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 * 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);
+ }
+ s->ins = NULL;
+ s->outs = NULL;
+ s->next = NULL;
+ FREE(s);
+}
+
+/*
+ * newarc - set up a new arc within an NFA
+ */
+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 duplicates */
+ for (a = from->outs; a != NULL; a = a->outchain)
+ if (a->to == to && a->co == co && a->type == t)
+ return;
+
+ 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. Not
+ * only is this easier, it has the very useful side effect that
+ * deleting the most-recently-added arc is the cheapest case rather
+ * than the most expensive one.
+ */
+ a->inchain = to->ins;
+ to->ins = a;
+ a->outchain = from->outs;
+ from->outs = a;
+
+ from->nouts++;
+ to->nins++;
+
+ if (COLORED(a) && nfa->parent == NULL)
+ colorchain(nfa->cm, a);
+
+ return;
+}
+
+/*
+ * allocarc - allocate a new out-arc within a state
+ */
+static struct arc * /* NULL for failure */
+allocarc(struct nfa * nfa,
+ struct state * s)
+{
+ struct arc *a;
+ struct arcbatch *new;
+ int i;
+
+ /* 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)
+ {
+ new = (struct arcbatch *) MALLOC(sizeof(struct arcbatch));
+ if (new == NULL)
+ {
+ NERR(REG_ESPACE);
+ return NULL;
+ }
+ new->next = s->oas.next;
+ s->oas.next = new;
+
+ for (i = 0; i < ABSIZE; i++)
+ {
+ new->a[i].type = 0;
+ new->a[i].freechain = &new->a[i + 1];
+ }
+ new->a[ABSIZE - 1].freechain = NULL;
+ s->free = &new->a[0];
+ }
+ assert(s->free != NULL);
+
+ a = s->free;
+ s->free = a->freechain;
+ 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 *a;
+
+ 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);
+ assert(from->outs != NULL);
+ a = from->outs;
+ if (a == victim) /* simple case: first in chain */
+ from->outs = victim->outchain;
+ else
+ {
+ for (; a != NULL && a->outchain != victim; a = a->outchain)
+ continue;
+ assert(a != NULL);
+ a->outchain = victim->outchain;
+ }
+ from->nouts--;
+
+ /* take it off target's in-chain */
+ assert(to != NULL);
+ assert(to->ins != NULL);
+ a = to->ins;
+ if (a == victim) /* simple case: first in chain */
+ to->ins = victim->inchain;
+ else
+ {
+ for (; a != NULL && a->inchain != victim; a = a->inchain)
+ continue;
+ assert(a != NULL);
+ a->inchain = victim->inchain;
+ }
+ to->nins--;
+
+ /* clean up and place on free list */
+ victim->type = 0;
+ victim->from = NULL; /* precautions... */
+ victim->to = NULL;
+ victim->inchain = NULL;
+ victim->outchain = NULL;
+ victim->freechain = from->free;
+ from->free = victim;
+}
+
+/*
+ * 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,
+ 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 * nfa,
+ struct arc * oa,
+ struct state * from,
+ struct state * to)
+{
+ newarc(nfa, oa->type, oa->co, from, to);
+}
+
+/*
+ * 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 desire
+ * for duplicate suppression, which makes it easier to just make new
+ * ones to exploit the suppression built into newarc.
+ */
+static void
+moveins(struct nfa * nfa,
+ struct state * old,
+ struct state * new)
+{
+ struct arc *a;
+
+ assert(old != new);
+
+ while ((a = old->ins) != NULL)
+ {
+ cparc(nfa, a, a->from, new);
+ freearc(nfa, a);
+ }
+ assert(old->nins == 0);
+ assert(old->ins == NULL);
+}
+
+/*
+ * copyins - copy all in arcs of a state to another state
+ */
+static void
+copyins(struct nfa * nfa,
+ struct state * old,
+ struct state * new)
+{
+ struct arc *a;
+
+ assert(old != new);
+
+ for (a = old->ins; a != NULL; a = a->inchain)
+ cparc(nfa, a, a->from, new);
+}
+
+/*
+ * moveouts - move all out arcs of a state to another state
+ */
+static void
+moveouts(struct nfa * nfa,
+ struct state * old,
+ struct state * new)
+{
+ struct arc *a;
+
+ assert(old != new);
+
+ while ((a = old->outs) != NULL)
+ {
+ cparc(nfa, a, new, a->to);
+ freearc(nfa, a);
+ }
+}
+
+/*
+ * copyouts - copy all out arcs of a state to another state
+ */
+static void
+copyouts(struct nfa * nfa,
+ struct state * old,
+ struct state * new)
+{
+ struct arc *a;
+
+ assert(old != new);
+
+ for (a = old->outs; a != NULL; a = a->outchain)
+ cparc(nfa, a, new, a->to);
+}
+
+/*
+ * cloneouts - copy out arcs of a state to another state pair, modifying type
+ */
+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 * 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 * 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 * 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;
+
+ 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);
+ 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 * 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 * 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 /* 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
+ 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 */
+ return analyze(nfa); /* and analysis */
+}
+
+/*
+ * pullback - pull back constraints backward to (with luck) 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;
+ 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;
+ for (a = s->outs; a != NULL && !NISERR(); a = nexta)
+ {
+ nexta = a->outchain;
+ if (a->type == '^' || a->type == BEHIND)
+ if (pull(nfa, a))
+ progress = 1;
+ assert(nexta == NULL || s->no != FREESTATE);
+ }
+ }
+ if (progress && f != NULL)
+ dumpnfa(nfa, f);
+ } while (progress && !NISERR());
+ if (NISERR())
+ return;
+
+ 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
+ * A significant property of this function is that it deletes at most
+ * one state -- the constraint's from state -- and only if the constraint
+ * was that state's last outarc.
+ */
+static int /* 0 couldn't, 1 could */
+pull(struct nfa * nfa,
+ struct arc * con)
+{
+ struct state *from = con->from;
+ struct state *to = con->to;
+ struct arc *a;
+ struct arc *nexta;
+ struct state *s;
+
+ if (from == to)
+ { /* circular constraint is pointless */
+ freearc(nfa, con);
+ return 1;
+ }
+ 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 */
+ if (from->nouts > 1)
+ {
+ s = newstate(nfa);
+ if (NISERR())
+ return 0;
+ assert(to != from); /* con is not an inarc */
+ copyins(nfa, from, s); /* duplicate inarcs */
+ cparc(nfa, con, s, to); /* move constraint arc */
+ freearc(nfa, con);
+ from = s;
+ con = from->outs;
+ }
+ assert(from->nouts == 1);
+
+ /* propagate the constraint into the from state's inarcs */
+ for (a = from->ins; a != NULL; 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 */
+ s = newstate(nfa);
+ if (NISERR())
+ return 0;
+ cparc(nfa, a, s, to); /* anticipate move */
+ cparc(nfa, con, a->from, s);
+ if (NISERR())
+ return 0;
+ freearc(nfa, a);
+ break;
+ default:
+ assert(NOTREACHED);
+ break;
+ }
+ }
+
+ /* remaining inarcs, if any, incorporate the constraint */
+ moveins(nfa, from, to);
+ dropstate(nfa, from); /* will free the constraint */
+ return 1;
+}
+
+/*
+ * pushfwd - push forward constraints forward to (with luck) 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;
+ 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;
+ for (a = s->ins; a != NULL && !NISERR(); a = nexta)
+ {
+ nexta = a->inchain;
+ if (a->type == '$' || a->type == AHEAD)
+ if (push(nfa, a))
+ progress = 1;
+ assert(nexta == NULL || s->no != FREESTATE);
+ }
+ }
+ if (progress && f != NULL)
+ dumpnfa(nfa, f);
+ } while (progress && !NISERR());
+ if (NISERR())
+ return;
+
+ for (a = nfa->post->ins; a != NULL; a = nexta)
+ {
+ nexta = a->inchain;
+ if (a->type == '$')
+ {
+ 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
+ * A significant property of this function is that it deletes at most
+ * one state -- the constraint's to state -- and only if the constraint
+ * was that state's last inarc.
+ */
+static int /* 0 couldn't, 1 could */
+push(struct nfa * nfa,
+ struct arc * con)
+{
+ struct state *from = con->from;
+ struct state *to = con->to;
+ struct arc *a;
+ struct arc *nexta;
+ struct state *s;
+
+ if (to == from)
+ { /* circular constraint is pointless */
+ freearc(nfa, con);
+ return 1;
+ }
+ 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 */
+ if (to->nins > 1)
+ {
+ s = newstate(nfa);
+ if (NISERR())
+ return 0;
+ copyouts(nfa, to, s); /* duplicate outarcs */
+ cparc(nfa, con, from, s); /* move constraint */
+ freearc(nfa, con);
+ to = s;
+ con = to->ins;
+ }
+ assert(to->nins == 1);
+
+ /* propagate the constraint into the to state's outarcs */
+ for (a = to->outs; a != NULL; 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 */
+ s = newstate(nfa);
+ if (NISERR())
+ return 0;
+ cparc(nfa, con, s, a->to); /* anticipate move */
+ cparc(nfa, a, from, s);
+ if (NISERR())
+ return 0;
+ freearc(nfa, a);
+ break;
+ default:
+ assert(NOTREACHED);
+ break;
+ }
+ }
+
+ /* remaining outarcs, if any, incorporate the constraint */
+ moveouts(nfa, to, from);
+ dropstate(nfa, to); /* will free the constraint */
+ 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 * 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 * nfa,
+ FILE *f) /* for debug output; NULL none */
+{
+ struct state *s;
+ struct state *nexts;
+ struct arc *a;
+ struct arc *nexta;
+ int progress;
+
+ /* find and eliminate empties until there are no more */
+ do
+ {
+ progress = 0;
+ for (s = nfa->states; s != NULL && !NISERR(); s = nexts)
+ {
+ nexts = s->next;
+ for (a = s->outs; a != NULL && !NISERR(); a = nexta)
+ {
+ nexta = a->outchain;
+ if (a->type == EMPTY && unempty(nfa, a))
+ progress = 1;
+ assert(nexta == NULL || s->no != FREESTATE);
+ }
+ }
+ if (progress && f != NULL)
+ dumpnfa(nfa, f);
+ } while (progress && !NISERR());
+}
+
+/*
+ * unempty - optimize out an EMPTY arc, if possible
+ *
+ * Actually, as it stands this function always succeeds, but the return
+ * value is kept with an eye on possible future changes.
+ */
+static int /* 0 couldn't, 1 could */
+unempty(struct nfa * nfa,
+ struct arc * a)
+{
+ struct state *from = a->from;
+ struct state *to = a->to;
+ int usefrom; /* work on from, as opposed to to? */
+
+ assert(a->type == EMPTY);
+ assert(from != nfa->pre && to != nfa->post);
+
+ if (from == to)
+ { /* vacuous loop */
+ freearc(nfa, a);
+ return 1;
+ }
+
+ /* decide which end to work on */
+ usefrom = 1; /* default: attack from */
+ if (from->nouts > to->nins)
+ usefrom = 0;
+ else if (from->nouts == to->nins)
+ {
+ /* decide on secondary issue: move/copy fewest arcs */
+ if (from->nins > to->nouts)
+ usefrom = 0;
+ }
+
+ freearc(nfa, a);
+ if (usefrom)
+ {
+ if (from->nouts == 0)
+ {
+ /* was the state's only outarc */
+ moveins(nfa, from, to);
+ freestate(nfa, from);
+ }
+ else
+ copyins(nfa, from, to);
+ }
+ else
+ {
+ if (to->nins == 0)
+ {
+ /* was the state's only inarc */
+ moveouts(nfa, to, from);
+ freestate(nfa, to);
+ }
+ else
+ copyouts(nfa, to, from);
+ }
+
+ return 1;
+}
+
+/*
+ * cleanup - clean up NFA after optimizations
+ */
+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, (struct state *) 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 * 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 * 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 /* 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 - compact 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 += 1 + s->nouts + 1;
+ /* 1 as a fake for flags, nouts for arcs, 1 as endmarker */
+ }
+
+ cnfa->states = (struct carc **) MALLOC(nstates * sizeof(struct carc *));
+ cnfa->arcs = (struct carc *) MALLOC(narcs * sizeof(struct carc));
+ if (cnfa->states == NULL || cnfa->arcs == NULL)
+ {
+ 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->states[s->no] = ca;
+ ca->co = 0; /* clear and skip flags "arc" */
+ 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:
+ assert(NOTREACHED);
+ break;
+ }
+ carcsort(first, ca - 1);
+ 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->states[a->to->no]->co = 1;
+ cnfa->states[nfa->pre->no]->co = 1;
+}
+
+/*
+ * carcsort - sort compacted-NFA arcs by color
+ *
+ * Really dumb algorithm, but if the list is long enough for that to matter,
+ * you're in real trouble anyway.
+ */
+static void
+carcsort(struct carc * first,
+ struct carc * last)
+{
+ struct carc *p;
+ struct carc *q;
+ struct carc tmp;
+
+ if (last - first <= 1)
+ return;
+
+ for (p = first; p <= last; p++)
+ for (q = p; q <= last; q++)
+ if (p->co > q->co ||
+ (p->co == q->co && p->to > q->to))
+ {
+ assert(p != q);
+ tmp = *p;
+ *p = *q;
+ *q = tmp;
+ }
+}
+
+/*
+ * freecnfa - free a compacted NFA
+ */
+static void
+freecnfa(struct cnfa * cnfa)
+{
+ assert(cnfa->nstates != 0); /* not empty already */
+ cnfa->nstates = 0;
+ FREE(cnfa->states);
+ FREE(cnfa->arcs);
+}
+
+/*
+ * dumpnfa - dump an NFA in human-readable form
+ */
+static void
+dumpnfa(struct nfa * nfa,
+ FILE *f)
+{
+#ifdef REG_DEBUG
+ struct state *s;
+
+ 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);
+ 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);
+ 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 * s,
+ FILE *f)
+{
+ int pos;
+
+ assert(s->nouts > 0);
+ /* printing arcs in reverse order is usually clearer */
+ pos = dumprarcs(s->outs, s, f, 1);
+ if (pos != 1)
+ fprintf(f, "\n");
+}
+
+/*
+ * dumprarcs - dump remaining outarcs, recursively, in reverse order
+ */
+static int /* resulting print position */
+dumprarcs(struct arc * a,
+ struct state * s,
+ FILE *f,
+ int pos) /* initial print position */
+{
+ if (a->outchain != NULL)
+ pos = dumprarcs(a->outchain, s, f, pos);
+ dumparc(a, s, f);
+ if (pos == 5)
+ {
+ fprintf(f, "\n");
+ pos = 1;
+ }
+ else
+ pos++;
+ return pos;
+}
+
+/*
+ * dumparc - dump one outarc in readable form, including prefixing tab
+ */
+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 /* 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");
+ fprintf(f, "\n");
+ for (st = 0; st < cnfa->nstates; st++)
+ dumpcstate(st, cnfa->states[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 carc * ca,
+ struct cnfa * cnfa,
+ FILE *f)
+{
+ int i;
+ int pos;
+
+ fprintf(f, "%d%s", st, (ca[0].co) ? ":" : ".");
+ pos = 1;
+ for (i = 1; ca[i].co != COLORLESS; i++)
+ {
+ if (ca[i].co < cnfa->ncolors)
+ fprintf(f, "\t[%ld]->%d", (long) ca[i].co, ca[i].to);
+ else
+ fprintf(f, "\t:%ld:->%d", (long) ca[i].co - cnfa->ncolors,
+ ca[i].to);
+ if (pos == 5)
+ {
+ fprintf(f, "\n");
+ pos = 1;
+ }
+ else
+ pos++;
+ }
+ if (i == 1 || pos != 1)
+ fprintf(f, "\n");
+ fflush(f);
+}
+
+#endif /* REG_DEBUG */
projects / wxWidgets.git / commitdiff
