/*
* 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))
/*
- 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) {
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 *);
*/
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);
}
}
/*
- 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 ; i<ABSIZE ; i++) {
newAb->a[i].type = 0;
newAb->a[i].freechain = &newAb->a[i+1];
}
newAb->a[ABSIZE-1].freechain = NULL;
s->free = &newAb->a[0];
}
assert(s->free != NULL);
a = s->free;
s->free = a->freechain;
return a;
}
/*
- freearc - free an arc
^ static VOID freearc(struct nfa *, struct arc *);
*/
static void
freearc(
struct nfa *nfa,
struct arc *victim)
{
struct state *from = victim->from;
struct state *to = victim->to;
struct arc *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->inchain!=victim ; a=a->inchain) {
assert(a->inchain != NULL);
continue;
}
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 *, 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);
}
/*
- 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 *, struct state *, struct state *);
*/
static void
moveins(
struct nfa *nfa,
struct state *oldState,
struct state *newState)
{
struct arc *a;
assert(oldState != newState);
while ((a = oldState->ins) != NULL) {
cparc(nfa, a, a->from, newState);
freearc(nfa, a);
}
assert(oldState->nins == 0);
assert(oldState->ins == NULL);
}
/*
- copyins - copy all in arcs of a state to another state
^ static VOID copyins(struct nfa *, struct state *, struct state *);
*/
static void
copyins(
struct nfa *nfa,
struct state *oldState,
struct state *newState)
{
struct arc *a;
assert(oldState != newState);
for (a=oldState->ins ; a!=NULL ; a=a->inchain) {
cparc(nfa, a, a->from, newState);
}
}
/*
- 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)
{
struct arc *a;
assert(oldState != newState);
while ((a = oldState->outs) != NULL) {
cparc(nfa, a, newState, a->to);
freearc(nfa, a);
}
}
/*
- copyouts - copy all out arcs of a state to another state
^ static VOID copyouts(struct nfa *, struct state *, struct state *);
*/
static void
copyouts(
struct nfa *nfa,
struct state *oldState,
struct state *newState)
{
struct arc *a;
assert(oldState != newState);
for (a=oldState->outs ; a!=NULL ; a=a->outchain) {
cparc(nfa, a, 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 *);
*/
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");
}
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 */
return analyze(nfa); /* and analysis */
}
/*
- pullback - pull back constraints backward to (with luck) 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;
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 pull(struct nfa *, struct arc *);
*/
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;
}
/*
* DGP 2007-11-15: Cloning a state with a circular constraint on its list
* of outs can lead to trouble [Bug 1810038], so get rid of them first.
*/
for (a = from->outs; a != NULL; a = nexta) {
nexta = a->outchain;
switch (a->type) {
case '^':
case '$':
case BEHIND:
case AHEAD:
if (from == a->to) {
freearc(nfa, a);
}
break;
}
}
/*
* First, clone from state if necessary to avoid other outarcs.
*/
if (from->nouts > 1) {
s = newstate(nfa);
if (NISERR()) {
return 0;
}
assert(to != from); /* con is not an inarc */
copyins(nfa, from, s); /* duplicate inarcs */
cparc(nfa, con, s, to); /* move constraint arc */
freearc(nfa, con);
from = s;
con = from->outs;
}
assert(from->nouts == 1);
/*
* Propagate the constraint into the from state's inarcs.
*/
for (a=from->ins ; a!=NULL ; a=nexta) {
nexta = a->inchain;
switch (combine(con, a)) {
case INCOMPATIBLE: /* destroy the arc */
freearc(nfa, a);
break;
case SATISFIED: /* no action needed */
break;
case COMPATIBLE: /* swap the two arcs, more or less */
s = newstate(nfa);
if (NISERR()) {
return 0;
}
cparc(nfa, a, s, to); /* anticipate move */
cparc(nfa, con, a->from, s);
if (NISERR()) {
return 0;
}
freearc(nfa, a);
break;
default:
assert(NOTREACHED);
break;
}
}
/*
* Remaining inarcs, if any, incorporate the constraint.
*/
moveins(nfa, from, to);
dropstate(nfa, from); /* will free the constraint */
return 1;
}
/*
- pushfwd - push forward constraints forward to (with luck) eliminate them
^ static VOID pushfwd(struct nfa *, FILE *);
*/
static void
pushfwd(
struct nfa *nfa,
FILE *f) /* for debug output; NULL none */
{
struct state *s;
struct state *nexts;
struct arc *a;
struct arc *nexta;
int progress;
/*
* Find and push until there are no more.
*/
do {
progress = 0;
for (s=nfa->states ; s!=NULL && !NISERR() ; s=nexts) {
nexts = s->next;
for (a = s->ins; a != NULL && !NISERR(); a = nexta) {
nexta = a->inchain;
if (a->type == '$' || 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 == '$') {
assert(a->co == 0 || a->co == 1);
newarc(nfa, PLAIN, nfa->eos[a->co], a->from, a->to);
freearc(nfa, a);
}
}
}
/*
- push - push a forward constraint forward past its destination state
* A significant property of this function is that it deletes at most
* one state -- the constraint's to state -- and only if the constraint
* was that state's last inarc.
^ static int push(struct nfa *, struct arc *);
*/
static int /* 0 couldn't, 1 could */
push(
struct nfa *nfa,
struct arc *con)
{
struct state *from = con->from;
struct state *to = con->to;
struct arc *a;
struct arc *nexta;
struct state *s;
if (to == from) { /* circular constraint is pointless */
freearc(nfa, con);
return 1;
}
if (to->flag) { /* can't push forward beyond end */
return 0;
}
if (to->nouts == 0) { /* dead end */
freearc(nfa, con);
return 1;
}
/*
* DGP 2007-11-15: Here we duplicate the same protections as appear
* in pull() above to avoid troubles with cloning a state with a
* circular constraint on its list of ins. It is not clear whether
* this is necessary, or is protecting against a "can't happen".
* Any test case that actually leads to a freearc() call here would
* be a welcome addition to the test suite.
*/
for (a = to->ins; a != NULL; a = nexta) {
nexta = a->inchain;
switch (a->type) {
case '^':
case '$':
case BEHIND:
case AHEAD:
if (a->from == to) {
freearc(nfa, a);
}
break;
}
}
/*
* 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 *, struct arc *);
*/
static int
combine(
struct arc *con,
struct arc *a)
{
#define CA(ct,at) (((ct)<<CHAR_BIT) | (at))
switch (CA(con->type, a->type)) {
case CA('^', PLAIN): /* newlines are handled separately */
case CA('$', PLAIN):
return INCOMPATIBLE;
break;
case CA(AHEAD, PLAIN): /* color constraints meet colors */
case CA(BEHIND, PLAIN):
if (con->co == a->co) {
return SATISFIED;
}
return INCOMPATIBLE;
break;
case CA('^', '^'): /* collision, similar constraints */
case CA('$', '$'):
case CA(AHEAD, AHEAD):
case CA(BEHIND, BEHIND):
if (con->co == a->co) { /* true duplication */
return SATISFIED;
}
return INCOMPATIBLE;
break;
case CA('^', BEHIND): /* collision, dissimilar constraints */
case CA(BEHIND, '^'):
case CA('$', AHEAD):
case CA(AHEAD, '$'):
return INCOMPATIBLE;
break;
case CA('^', '$'): /* constraints passing each other */
case CA('^', AHEAD):
case CA(BEHIND, '$'):
case CA(BEHIND, AHEAD):
case CA('$', '^'):
case CA('$', BEHIND):
case CA(AHEAD, '^'):
case CA(AHEAD, BEHIND):
case CA('^', LACON):
case CA(BEHIND, LACON):
case CA('$', LACON):
case CA(AHEAD, LACON):
return COMPATIBLE;
break;
}
assert(NOTREACHED);
return INCOMPATIBLE; /* for benefit of blind compilers */
}
/*
- fixempties - get rid of EMPTY arcs
^ static VOID fixempties(struct nfa *, FILE *);
*/
static void
fixempties(
struct nfa *nfa,
FILE *f) /* for debug output; NULL none */
{
struct state *s;
struct state *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->no != FREESTATE; 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 unempty(struct nfa *, struct arc *);
*/
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 *);
*/
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 - compact 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:
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 *, struct carc *);
*/
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 *);
*/
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;
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 */
/*
^ #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;
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 dumprarcs(struct arc *, struct state *, FILE *, int);
*/
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 *, 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:
*/
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