/*
* miss - handle a stateset cache miss
*
* css is the current stateset, co is the color of the current input character,
* cp points to the character after that (which is where we may need to test
* LACONs). start does not affect matching behavior but is needed for pickss'
* heuristics about which stateset cache entry to replace.
*
* Ordinarily, returns the address of the next stateset (the one that is
* valid after consuming the input character). Returns NULL if no valid
* NFA states remain, ie we have a certain match failure.
* Internal errors also return NULL, with v->err set.
*/
static struct sset *
miss(struct vars * v,
struct dfa * d,
struct sset * css,
pcolor co,
chr *cp, /* next chr */
chr *start) /* where the attempt got started */
{
struct cnfa *cnfa = d->cnfa;
int i;
unsigned h;
struct carc *ca;
struct sset *p;
int ispost;
int noprogress;
int gotstate;
int dolacons;
int sawlacons;
/* for convenience, we can be called even if it might not be a miss */
if (css->outs[co] != NULL)
{
FDEBUG(("hit\n"));
return css->outs[co];
}
FDEBUG(("miss\n"));
/*
* Checking for operation cancel in the inner text search loop seems
* unduly expensive. As a compromise, check during cache misses.
*/
if (CANCEL_REQUESTED(v->re))
{
ERR(REG_CANCEL);
return NULL;
}
/*
* What set of states would we end up in after consuming the co character?
* We first consider PLAIN arcs that consume the character, and then look
* to see what LACON arcs could be traversed after consuming it.
*/
for (i = 0; i < d->wordsper; i++)
d->work[i] = 0; /* build new stateset bitmap in d->work */
ispost = 0;
noprogress = 1;
gotstate = 0;
for (i = 0; i < d->nstates; i++)
if (ISBSET(css->states, i))
for (ca = cnfa->states[i]; ca->co != COLORLESS; ca++)
if (ca->co == co)
{
BSET(d->work, ca->to);
gotstate = 1;
if (ca->to == cnfa->post)
ispost = 1;
if (!(cnfa->stflags[ca->to] & CNFA_NOPROGRESS))
noprogress = 0;
FDEBUG(("%d -> %d\n", i, ca->to));
}
if (!gotstate)
return NULL; /* character cannot reach any new state */
dolacons = (cnfa->flags & HASLACONS);
sawlacons = 0;
/* outer loop handles transitive closure of reachable-by-LACON states */
while (dolacons)
{
dolacons = 0;
for (i = 0; i < d->nstates; i++)
if (ISBSET(d->work, i))
for (ca = cnfa->states[i]; ca->co != COLORLESS; ca++)
{
if (ca->co < cnfa->ncolors)
continue; /* not a LACON arc */
if (ISBSET(d->work, ca->to))
continue; /* arc would be a no-op anyway */
sawlacons = 1; /* this LACON affects our result */
if (!lacon(v, cnfa, cp, ca->co))
{
if (ISERR())
return NULL;
continue; /* LACON arc cannot be traversed */
}
if (ISERR())
return NULL;
BSET(d->work, ca->to);
dolacons = 1;
if (ca->to == cnfa->post)
ispost = 1;
if (!(cnfa->stflags[ca->to] & CNFA_NOPROGRESS))
noprogress = 0;
FDEBUG(("%d :> %d\n", i, ca->to));
}
}
h = HASH(d->work, d->wordsper);
/* Is this stateset already in the cache? */
for (p = d->ssets, i = d->nssused; i > 0; p++, i--)
if (HIT(h, d->work, p, d->wordsper))
{
FDEBUG(("cached c%d\n", (int) (p - d->ssets)));
break; /* NOTE BREAK OUT */
}
if (i == 0)
{ /* nope, need a new cache entry */
p = getvacant(v, d, cp, start);
if (p == NULL)
return NULL;
assert(p != css);
for (i = 0; i < d->wordsper; i++)
p->states[i] = d->work[i];
p->hash = h;
p->flags = (ispost) ? POSTSTATE : 0;
if (noprogress)
p->flags |= NOPROGRESS;
/* lastseen to be dealt with by caller */
}
/*
* Link new stateset to old, unless a LACON affected the result, in which
* case we don't create the link. That forces future transitions across
* this same arc (same prior stateset and character color) to come through
* miss() again, so that we can recheck the LACON(s), which might or might
* not pass since context will be different.
*/
if (!sawlacons)
{
FDEBUG(("c%d[%d]->c%d\n",
(int) (css - d->ssets), co, (int) (p - d->ssets)));
css->outs[co] = p;
css->inchain[co] = p->ins;
p->ins.ss = css;
p->ins.co = (color) co;
}
return p;
}
/*
* cdissect - check backrefs and determine subexpression matches
*
* cdissect recursively processes a subre tree to check matching of backrefs
* and/or identify submatch boundaries for capture nodes. The proposed match
* runs from "begin" to "end" (not including "end"), and we are basically
* "dissecting" it to see where the submatches are.
*
* Before calling any level of cdissect, the caller must have run the node's
* DFA and found that the proposed substring satisfies the DFA. (We make
* the caller do that because in concatenation and iteration nodes, it's
* much faster to check all the substrings against the child DFAs before we
* recurse.) Also, caller must have cleared subexpression match data via
* zaptreesubs (or zapallsubs at the top level).
*/
static int /* regexec return code */
cdissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
int er;
assert(t != NULL);
MDEBUG(("cdissect %ld-%ld %c\n", LOFF(begin), LOFF(end), t->op));
/* handy place to check for operation cancel */
if (CANCEL_REQUESTED(v->re))
return REG_CANCEL;
switch (t->op)
{
case '=': /* terminal node */
assert(t->left == NULL && t->right == NULL);
er = REG_OKAY; /* no action, parent did the work */
break;
case 'b': /* back reference */
assert(t->left == NULL && t->right == NULL);
er = cbrdissect(v, t, begin, end);
break;
case '.': /* concatenation */
assert(t->left != NULL && t->right != NULL);
if (t->left->flags & SHORTER) /* reverse scan */
er = crevcondissect(v, t, begin, end);
else
er = ccondissect(v, t, begin, end);
break;
case '|': /* alternation */
assert(t->left != NULL);
er = caltdissect(v, t, begin, end);
break;
case '*': /* iteration */
assert(t->left != NULL);
if (t->left->flags & SHORTER) /* reverse scan */
er = creviterdissect(v, t, begin, end);
else
er = citerdissect(v, t, begin, end);
break;
case '(': /* capturing */
assert(t->left != NULL && t->right == NULL);
assert(t->subno > 0);
er = cdissect(v, t->left, begin, end);
if (er == REG_OKAY)
subset(v, t, begin, end);
break;
default:
er = REG_ASSERT;
break;
}
/*
* We should never have a match failure unless backrefs lurk below;
* otherwise, either caller failed to check the DFA, or there's some
* inconsistency between the DFA and the node's innards.
*/
assert(er != REG_NOMATCH || (t->flags & BACKR));
return er;
}
