/*
* 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->size = 0;
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;
}
/*
- TooManyStates - checks if the max states exceeds the compile-time value
^ static int TooManyStates(struct nfa *);
*/
static int
TooManyStates(
struct nfa *nfa)
{
struct nfa *parent = nfa->parent;
size_t sz = nfa->size;
while (parent != NULL) {
sz = parent->size;
parent = parent->parent;
}
if (sz > REG_MAX_STATES) {
return 1;
}
return 0;
}
/*
- IncrementSize - increases the tracked size of the NFA and its parents.
^ static void IncrementSize(struct nfa *);
*/
static void
IncrementSize(
struct nfa *nfa)
{
struct nfa *parent = nfa->parent;
nfa->size++;
while (parent != NULL) {
parent->size++;
parent = parent->parent;
}
}
/*
- DecrementSize - increases the tracked size of the NFA and its parents.
^ static void DecrementSize(struct nfa *);
*/
static void
DecrementSize(
struct nfa *nfa)
{
struct nfa *parent = nfa->parent;
nfa->size--;
while (parent != NULL) {
parent->size--;
parent = parent->parent;
}
}
/*
- 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 (TooManyStates(nfa)) {
/* XXX: add specific error for this */
NERR(REG_ETOOBIG);
return NULL;
}
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;
/*
* Track the current size and the parent size.
*/
IncrementSize(nfa);
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;
DecrementSize(nfa);
}
/*
- 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);
}
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 *, 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 = (struct arcbatch *)
MALLOC(sizeof(struct arcbatch));
int i;
if (newAb == NULL) {
NERR(REG_ESPACE);
return NULL;
}
newAb->next = s->oas.next;
s->oas.next = newAb;
for (i=0 ; ia[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);
/* 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 */
{
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, NULL);
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)<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 += 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:
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->states[a->to->no]->co = 1;
}
cnfa->states[nfa->pre->no]->co = 1;
}
/*
- 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->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->states[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 carc *, struct cnfa *, FILE *);
*/
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
*/
#endif /* ifdef REG_DEBUG */
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/