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PostgreSQL/src/backend/regex/regexec.c
Tom Lane ee3a81f0a0 Change regexp engine's ccondissect/crevdissect routines to perform DFA 
matching before recursing instead of after.  The DFA match eliminates
unworkable midpoint choices a lot faster than the recursive check, in most
cases, so doing it first can speed things up; particularly in pathological
cases such as recently exhibited by Michael Glaesemann.

In addition, apply some cosmetic changes that were applied upstream (in the
Tcl project) at the same time, in order to sync with upstream version 1.15
of regexec.c.

Upstream apparently intends to backpatch this, so I will too.  The
pathological behavior could be unpleasant if encountered in the field,
which seems to justify any risk of introducing new bugs.

Tom Lane, reviewed by Donal K. Fellows of Tcl project
2010-02-01 02:45:29 +00:00

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/*
* re_*exec and friends - match REs
*
* 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.
*
* $PostgreSQL: pgsql/src/backend/regex/regexec.c,v 1.28 2010/02/01 02:45:29 tgl Exp $
*
*/
#include "regex/regguts.h"
/* lazy-DFA representation */
struct arcp
{ /* "pointer" to an outarc */
struct sset *ss;
color co;
};
struct sset
{ /* state set */
unsigned *states; /* pointer to bitvector */
unsigned hash; /* hash of bitvector */
#define HASH(bv, nw) (((nw) == 1) ? *(bv) : hash(bv, nw))
#define HIT(h,bv,ss,nw) ((ss)->hash == (h) && ((nw) == 1 || \
memcmp(VS(bv), VS((ss)->states), (nw)*sizeof(unsigned)) == 0))
int flags;
#define STARTER 01 /* the initial state set */
#define POSTSTATE 02 /* includes the goal state */
#define LOCKED 04 /* locked in cache */
#define NOPROGRESS 010 /* zero-progress state set */
struct arcp ins; /* chain of inarcs pointing here */
chr *lastseen; /* last entered on arrival here */
struct sset **outs; /* outarc vector indexed by color */
struct arcp *inchain; /* chain-pointer vector for outarcs */
};
struct dfa
{
int nssets; /* size of cache */
int nssused; /* how many entries occupied yet */
int nstates; /* number of states */
int ncolors; /* length of outarc and inchain vectors */
int wordsper; /* length of state-set bitvectors */
struct sset *ssets; /* state-set cache */
unsigned *statesarea; /* bitvector storage */
unsigned *work; /* pointer to work area within statesarea */
struct sset **outsarea; /* outarc-vector storage */
struct arcp *incarea; /* inchain storage */
struct cnfa *cnfa;
struct colormap *cm;
chr *lastpost; /* location of last cache-flushed success */
chr *lastnopr; /* location of last cache-flushed NOPROGRESS */
struct sset *search; /* replacement-search-pointer memory */
int cptsmalloced; /* were the areas individually malloced? */
char *mallocarea; /* self, or master malloced area, or NULL */
};
#define WORK 1 /* number of work bitvectors needed */
/* setup for non-malloc allocation for small cases */
#define FEWSTATES 20 /* must be less than UBITS */
#define FEWCOLORS 15
struct smalldfa
{
struct dfa dfa;
struct sset ssets[FEWSTATES * 2];
unsigned statesarea[FEWSTATES * 2 + WORK];
struct sset *outsarea[FEWSTATES * 2 * FEWCOLORS];
struct arcp incarea[FEWSTATES * 2 * FEWCOLORS];
};
#define DOMALLOC ((struct smalldfa *)NULL) /* force malloc */
/* internal variables, bundled for easy passing around */
struct vars
{
regex_t *re;
struct guts *g;
int eflags; /* copies of arguments */
size_t nmatch;
regmatch_t *pmatch;
rm_detail_t *details;
chr *start; /* start of string */
chr *search_start; /* search start of string */
chr *stop; /* just past end of string */
int err; /* error code if any (0 none) */
regoff_t *mem; /* memory vector for backtracking */
struct smalldfa dfa1;
struct smalldfa dfa2;
};
#define VISERR(vv) ((vv)->err != 0) /* have we seen an error yet? */
#define ISERR() VISERR(v)
#define VERR(vv,e) (((vv)->err) ? (vv)->err : ((vv)->err = (e)))
#define ERR(e) VERR(v, e) /* record an error */
#define NOERR() {if (ISERR()) return v->err;} /* if error seen, return it */
#define OFF(p) ((p) - v->start)
#define LOFF(p) ((long)OFF(p))
/*
* forward declarations
*/
/* === regexec.c === */
static int find(struct vars *, struct cnfa *, struct colormap *);
static int cfind(struct vars *, struct cnfa *, struct colormap *);
static int cfindloop(struct vars *, struct cnfa *, struct colormap *, struct dfa *, struct dfa *, chr **);
static void zapsubs(regmatch_t *, size_t);
static void zapmem(struct vars *, struct subre *);
static void subset(struct vars *, struct subre *, chr *, chr *);
static int dissect(struct vars *, struct subre *, chr *, chr *);
static int condissect(struct vars *, struct subre *, chr *, chr *);
static int altdissect(struct vars *, struct subre *, chr *, chr *);
static int cdissect(struct vars *, struct subre *, chr *, chr *);
static int ccaptdissect(struct vars *, struct subre *, chr *, chr *);
static int ccondissect(struct vars *, struct subre *, chr *, chr *);
static int crevdissect(struct vars *, struct subre *, chr *, chr *);
static int cbrdissect(struct vars *, struct subre *, chr *, chr *);
static int caltdissect(struct vars *, struct subre *, chr *, chr *);
/* === rege_dfa.c === */
static chr *longest(struct vars *, struct dfa *, chr *, chr *, int *);
static chr *shortest(struct vars *, struct dfa *, chr *, chr *, chr *, chr **, int *);
static chr *lastcold(struct vars *, struct dfa *);
static struct dfa *newdfa(struct vars *, struct cnfa *, struct colormap *, struct smalldfa *);
static void freedfa(struct dfa *);
static unsigned hash(unsigned *, int);
static struct sset *initialize(struct vars *, struct dfa *, chr *);
static struct sset *miss(struct vars *, struct dfa *, struct sset *, pcolor, chr *, chr *);
static int lacon(struct vars *, struct cnfa *, chr *, pcolor);
static struct sset *getvacant(struct vars *, struct dfa *, chr *, chr *);
static struct sset *pickss(struct vars *, struct dfa *, chr *, chr *);
/*
* pg_regexec - match regular expression
*/
int
pg_regexec(regex_t *re,
const chr *string,
size_t len,
size_t search_start,
rm_detail_t *details,
size_t nmatch,
regmatch_t pmatch[],
int flags)
{
struct vars var;
register struct vars *v = &var;
int st;
size_t n;
int backref;
#define LOCALMAT 20
regmatch_t mat[LOCALMAT];
#define LOCALMEM 40
regoff_t mem[LOCALMEM];
/* sanity checks */
if (re == NULL || string == NULL || re->re_magic != REMAGIC)
return REG_INVARG;
if (re->re_csize != sizeof(chr))
return REG_MIXED;
/* setup */
v->re = re;
v->g = (struct guts *) re->re_guts;
if ((v->g->cflags & REG_EXPECT) && details == NULL)
return REG_INVARG;
if (v->g->info & REG_UIMPOSSIBLE)
return REG_NOMATCH;
backref = (v->g->info & REG_UBACKREF) ? 1 : 0;
v->eflags = flags;
if (v->g->cflags & REG_NOSUB)
nmatch = 0; /* override client */
v->nmatch = nmatch;
if (backref)
{
/* need work area */
if (v->g->nsub + 1 <= LOCALMAT)
v->pmatch = mat;
else
v->pmatch = (regmatch_t *) MALLOC((v->g->nsub + 1) *
sizeof(regmatch_t));
if (v->pmatch == NULL)
return REG_ESPACE;
v->nmatch = v->g->nsub + 1;
}
else
v->pmatch = pmatch;
v->details = details;
v->start = (chr *) string;
v->search_start = (chr *) string + search_start;
v->stop = (chr *) string + len;
v->err = 0;
if (backref)
{
/* need retry memory */
assert(v->g->ntree >= 0);
n = (size_t) v->g->ntree;
if (n <= LOCALMEM)
v->mem = mem;
else
v->mem = (regoff_t *) MALLOC(n * sizeof(regoff_t));
if (v->mem == NULL)
{
if (v->pmatch != pmatch && v->pmatch != mat)
FREE(v->pmatch);
return REG_ESPACE;
}
}
else
v->mem = NULL;
/* do it */
assert(v->g->tree != NULL);
if (backref)
st = cfind(v, &v->g->tree->cnfa, &v->g->cmap);
else
st = find(v, &v->g->tree->cnfa, &v->g->cmap);
/* copy (portion of) match vector over if necessary */
if (st == REG_OKAY && v->pmatch != pmatch && nmatch > 0)
{
zapsubs(pmatch, nmatch);
n = (nmatch < v->nmatch) ? nmatch : v->nmatch;
memcpy(VS(pmatch), VS(v->pmatch), n * sizeof(regmatch_t));
}
/* clean up */
if (v->pmatch != pmatch && v->pmatch != mat)
FREE(v->pmatch);
if (v->mem != NULL && v->mem != mem)
FREE(v->mem);
return st;
}
/*
* find - find a match for the main NFA (no-complications case)
*/
static int
find(struct vars * v,
struct cnfa * cnfa,
struct colormap * cm)
{
struct dfa *s;
struct dfa *d;
chr *begin;
chr *end = NULL;
chr *cold;
chr *open; /* open and close of range of possible starts */
chr *close;
int hitend;
int shorter = (v->g->tree->flags & SHORTER) ? 1 : 0;
/* first, a shot with the search RE */
s = newdfa(v, &v->g->search, cm, &v->dfa1);
assert(!(ISERR() && s != NULL));
NOERR();
MDEBUG(("\nsearch at %ld\n", LOFF(v->start)));
cold = NULL;
close = shortest(v, s, v->search_start, v->search_start, v->stop,
&cold, (int *) NULL);
freedfa(s);
NOERR();
if (v->g->cflags & REG_EXPECT)
{
assert(v->details != NULL);
if (cold != NULL)
v->details->rm_extend.rm_so = OFF(cold);
else
v->details->rm_extend.rm_so = OFF(v->stop);
v->details->rm_extend.rm_eo = OFF(v->stop); /* unknown */
}
if (close == NULL) /* not found */
return REG_NOMATCH;
if (v->nmatch == 0) /* found, don't need exact location */
return REG_OKAY;
/* find starting point and match */
assert(cold != NULL);
open = cold;
cold = NULL;
MDEBUG(("between %ld and %ld\n", LOFF(open), LOFF(close)));
d = newdfa(v, cnfa, cm, &v->dfa1);
assert(!(ISERR() && d != NULL));
NOERR();
for (begin = open; begin <= close; begin++)
{
MDEBUG(("\nfind trying at %ld\n", LOFF(begin)));
if (shorter)
end = shortest(v, d, begin, begin, v->stop,
(chr **) NULL, &hitend);
else
end = longest(v, d, begin, v->stop, &hitend);
NOERR();
if (hitend && cold == NULL)
cold = begin;
if (end != NULL)
break; /* NOTE BREAK OUT */
}
assert(end != NULL); /* search RE succeeded so loop should */
freedfa(d);
/* and pin down details */
assert(v->nmatch > 0);
v->pmatch[0].rm_so = OFF(begin);
v->pmatch[0].rm_eo = OFF(end);
if (v->g->cflags & REG_EXPECT)
{
if (cold != NULL)
v->details->rm_extend.rm_so = OFF(cold);
else
v->details->rm_extend.rm_so = OFF(v->stop);
v->details->rm_extend.rm_eo = OFF(v->stop); /* unknown */
}
if (v->nmatch == 1) /* no need for submatches */
return REG_OKAY;
/* submatches */
zapsubs(v->pmatch, v->nmatch);
return dissect(v, v->g->tree, begin, end);
}
/*
* cfind - find a match for the main NFA (with complications)
*/
static int
cfind(struct vars * v,
struct cnfa * cnfa,
struct colormap * cm)
{
struct dfa *s;
struct dfa *d;
chr *cold;
int ret;
s = newdfa(v, &v->g->search, cm, &v->dfa1);
NOERR();
d = newdfa(v, cnfa, cm, &v->dfa2);
if (ISERR())
{
assert(d == NULL);
freedfa(s);
return v->err;
}
ret = cfindloop(v, cnfa, cm, d, s, &cold);
freedfa(d);
freedfa(s);
NOERR();
if (v->g->cflags & REG_EXPECT)
{
assert(v->details != NULL);
if (cold != NULL)
v->details->rm_extend.rm_so = OFF(cold);
else
v->details->rm_extend.rm_so = OFF(v->stop);
v->details->rm_extend.rm_eo = OFF(v->stop); /* unknown */
}
return ret;
}
/*
* cfindloop - the heart of cfind
*/
static int
cfindloop(struct vars * v,
struct cnfa * cnfa,
struct colormap * cm,
struct dfa * d,
struct dfa * s,
chr **coldp) /* where to put coldstart pointer */
{
chr *begin;
chr *end;
chr *cold;
chr *open; /* open and close of range of possible starts */
chr *close;
chr *estart;
chr *estop;
int er;
int shorter = v->g->tree->flags & SHORTER;
int hitend;
assert(d != NULL && s != NULL);
cold = NULL;
close = v->search_start;
do
{
MDEBUG(("\ncsearch at %ld\n", LOFF(close)));
close = shortest(v, s, close, close, v->stop, &cold, (int *) NULL);
if (close == NULL)
break; /* NOTE BREAK */
assert(cold != NULL);
open = cold;
cold = NULL;
MDEBUG(("cbetween %ld and %ld\n", LOFF(open), LOFF(close)));
for (begin = open; begin <= close; begin++)
{
MDEBUG(("\ncfind trying at %ld\n", LOFF(begin)));
estart = begin;
estop = v->stop;
for (;;)
{
if (shorter)
end = shortest(v, d, begin, estart,
estop, (chr **) NULL, &hitend);
else
end = longest(v, d, begin, estop,
&hitend);
if (hitend && cold == NULL)
cold = begin;
if (end == NULL)
break; /* NOTE BREAK OUT */
MDEBUG(("tentative end %ld\n", LOFF(end)));
zapsubs(v->pmatch, v->nmatch);
zapmem(v, v->g->tree);
er = cdissect(v, v->g->tree, begin, end);
if (er == REG_OKAY)
{
if (v->nmatch > 0)
{
v->pmatch[0].rm_so = OFF(begin);
v->pmatch[0].rm_eo = OFF(end);
}
*coldp = cold;
return REG_OKAY;
}
if (er != REG_NOMATCH)
{
ERR(er);
*coldp = cold;
return er;
}
if ((shorter) ? end == estop : end == begin)
{
/* no point in trying again */
*coldp = cold;
return REG_NOMATCH;
}
/* go around and try again */
if (shorter)
estart = end + 1;
else
estop = end - 1;
}
}
} while (close < v->stop);
*coldp = cold;
return REG_NOMATCH;
}
/*
* zapsubs - initialize the subexpression matches to "no match"
*/
static void
zapsubs(regmatch_t *p,
size_t n)
{
size_t i;
for (i = n - 1; i > 0; i--)
{
p[i].rm_so = -1;
p[i].rm_eo = -1;
}
}
/*
* zapmem - initialize the retry memory of a subtree to zeros
*/
static void
zapmem(struct vars * v,
struct subre * t)
{
if (t == NULL)
return;
assert(v->mem != NULL);
v->mem[t->retry] = 0;
if (t->op == '(')
{
assert(t->subno > 0);
v->pmatch[t->subno].rm_so = -1;
v->pmatch[t->subno].rm_eo = -1;
}
if (t->left != NULL)
zapmem(v, t->left);
if (t->right != NULL)
zapmem(v, t->right);
}
/*
* subset - set any subexpression relevant to a successful subre
*/
static void
subset(struct vars * v,
struct subre * sub,
chr *begin,
chr *end)
{
int n = sub->subno;
assert(n > 0);
if ((size_t) n >= v->nmatch)
return;
MDEBUG(("setting %d\n", n));
v->pmatch[n].rm_so = OFF(begin);
v->pmatch[n].rm_eo = OFF(end);
}
/*
* dissect - determine subexpression matches (uncomplicated case)
*/
static int /* regexec return code */
dissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
assert(t != NULL);
MDEBUG(("dissect %ld-%ld\n", LOFF(begin), LOFF(end)));
switch (t->op)
{
case '=': /* terminal node */
assert(t->left == NULL && t->right == NULL);
return REG_OKAY; /* no action, parent did the work */
case '|': /* alternation */
assert(t->left != NULL);
return altdissect(v, t, begin, end);
case 'b': /* back ref -- shouldn't be calling us! */
return REG_ASSERT;
case '.': /* concatenation */
assert(t->left != NULL && t->right != NULL);
return condissect(v, t, begin, end);
case '(': /* capturing */
assert(t->left != NULL && t->right == NULL);
assert(t->subno > 0);
subset(v, t, begin, end);
return dissect(v, t->left, begin, end);
default:
return REG_ASSERT;
}
}
/*
* condissect - determine concatenation subexpression matches (uncomplicated)
*/
static int /* regexec return code */
condissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
struct dfa *d;
struct dfa *d2;
chr *mid;
int i;
int shorter = (t->left->flags & SHORTER) ? 1 : 0;
chr *stop = (shorter) ? end : begin;
assert(t->op == '.');
assert(t->left != NULL && t->left->cnfa.nstates > 0);
assert(t->right != NULL && t->right->cnfa.nstates > 0);
d = newdfa(v, &t->left->cnfa, &v->g->cmap, &v->dfa1);
NOERR();
d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, &v->dfa2);
if (ISERR())
{
assert(d2 == NULL);
freedfa(d);
return v->err;
}
/* pick a tentative midpoint */
if (shorter)
mid = shortest(v, d, begin, begin, end, (chr **) NULL,
(int *) NULL);
else
mid = longest(v, d, begin, end, (int *) NULL);
if (mid == NULL)
{
freedfa(d);
freedfa(d2);
return REG_ASSERT;
}
MDEBUG(("tentative midpoint %ld\n", LOFF(mid)));
/* iterate until satisfaction or failure */
while (longest(v, d2, mid, end, (int *) NULL) != end)
{
/* that midpoint didn't work, find a new one */
if (mid == stop)
{
/* all possibilities exhausted! */
MDEBUG(("no midpoint!\n"));
freedfa(d);
freedfa(d2);
return REG_ASSERT;
}
if (shorter)
mid = shortest(v, d, begin, mid + 1, end, (chr **) NULL,
(int *) NULL);
else
mid = longest(v, d, begin, mid - 1, (int *) NULL);
if (mid == NULL)
{
/* failed to find a new one! */
MDEBUG(("failed midpoint!\n"));
freedfa(d);
freedfa(d2);
return REG_ASSERT;
}
MDEBUG(("new midpoint %ld\n", LOFF(mid)));
}
/* satisfaction */
MDEBUG(("successful\n"));
freedfa(d);
freedfa(d2);
i = dissect(v, t->left, begin, mid);
if (i != REG_OKAY)
return i;
return dissect(v, t->right, mid, end);
}
/*
* altdissect - determine alternative subexpression matches (uncomplicated)
*/
static int /* regexec return code */
altdissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
struct dfa *d;
int i;
assert(t != NULL);
assert(t->op == '|');
for (i = 0; t != NULL; t = t->right, i++)
{
MDEBUG(("trying %dth\n", i));
assert(t->left != NULL && t->left->cnfa.nstates > 0);
d = newdfa(v, &t->left->cnfa, &v->g->cmap, &v->dfa1);
if (ISERR())
return v->err;
if (longest(v, d, begin, end, (int *) NULL) == end)
{
MDEBUG(("success\n"));
freedfa(d);
return dissect(v, t->left, begin, end);
}
freedfa(d);
}
return REG_ASSERT; /* none of them matched?!? */
}
/*
* cdissect - determine subexpression matches (with complications)
* The retry memory stores the offset of the trial midpoint from begin,
* plus 1 so that 0 uniquely means "clean slate".
*/
static int /* regexec return code */
cdissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
assert(t != NULL);
MDEBUG(("cdissect %ld-%ld %c\n", LOFF(begin), LOFF(end), t->op));
switch (t->op)
{
case '=': /* terminal node */
assert(t->left == NULL && t->right == NULL);
return REG_OKAY; /* no action, parent did the work */
case '|': /* alternation */
assert(t->left != NULL);
return caltdissect(v, t, begin, end);
case 'b': /* back ref -- shouldn't be calling us! */
assert(t->left == NULL && t->right == NULL);
return cbrdissect(v, t, begin, end);
case '.': /* concatenation */
assert(t->left != NULL && t->right != NULL);
return ccondissect(v, t, begin, end);
case '(': /* capturing */
assert(t->left != NULL && t->right == NULL);
return ccaptdissect(v, t, begin, end);
default:
return REG_ASSERT;
}
}
/*
* ccaptdissect - capture subexpression matches (with complications)
*/
static int /* regexec return code */
ccaptdissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
int er;
assert(t->subno > 0);
er = cdissect(v, t->left, begin, end);
if (er == REG_OKAY)
subset(v, t, begin, end);
return er;
}
/*
* ccondissect - concatenation subexpression matches (with complications)
* The retry memory stores the offset of the trial midpoint from begin,
* plus 1 so that 0 uniquely means "clean slate".
*/
static int /* regexec return code */
ccondissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
struct dfa *d;
struct dfa *d2;
chr *mid;
int er;
assert(t->op == '.');
assert(t->left != NULL && t->left->cnfa.nstates > 0);
assert(t->right != NULL && t->right->cnfa.nstates > 0);
if (t->left->flags & SHORTER) /* reverse scan */
return crevdissect(v, t, begin, end);
d = newdfa(v, &t->left->cnfa, &v->g->cmap, DOMALLOC);
if (ISERR())
return v->err;
d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, DOMALLOC);
if (ISERR())
{
freedfa(d);
return v->err;
}
MDEBUG(("cconcat %d\n", t->retry));
/* pick a tentative midpoint */
if (v->mem[t->retry] == 0)
{
mid = longest(v, d, begin, end, (int *) NULL);
if (mid == NULL)
{
freedfa(d);
freedfa(d2);
return REG_NOMATCH;
}
MDEBUG(("tentative midpoint %ld\n", LOFF(mid)));
v->mem[t->retry] = (mid - begin) + 1;
}
else
{
mid = begin + (v->mem[t->retry] - 1);
MDEBUG(("working midpoint %ld\n", LOFF(mid)));
}
/* iterate until satisfaction or failure */
for (;;)
{
/* try this midpoint on for size */
if (longest(v, d2, mid, end, (int *) NULL) == end)
{
er = cdissect(v, t->left, begin, mid);
if (er == REG_OKAY)
{
er = cdissect(v, t->right, mid, end);
if (er == REG_OKAY)
{
/* satisfaction */
MDEBUG(("successful\n"));
freedfa(d);
freedfa(d2);
return REG_OKAY;
}
}
if (er != REG_OKAY && er != REG_NOMATCH)
{
freedfa(d);
freedfa(d2);
return er;
}
}
/* that midpoint didn't work, find a new one */
if (mid == begin)
{
/* all possibilities exhausted */
MDEBUG(("%d no midpoint\n", t->retry));
freedfa(d);
freedfa(d2);
return REG_NOMATCH;
}
mid = longest(v, d, begin, mid - 1, (int *) NULL);
if (mid == NULL)
{
/* failed to find a new one */
MDEBUG(("%d failed midpoint\n", t->retry));
freedfa(d);
freedfa(d2);
return REG_NOMATCH;
}
MDEBUG(("%d: new midpoint %ld\n", t->retry, LOFF(mid)));
v->mem[t->retry] = (mid - begin) + 1;
zapmem(v, t->left);
zapmem(v, t->right);
}
/* can't get here */
return REG_ASSERT;
}
/*
* crevdissect - determine backref shortest-first subexpression matches
* The retry memory stores the offset of the trial midpoint from begin,
* plus 1 so that 0 uniquely means "clean slate".
*/
static int /* regexec return code */
crevdissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
struct dfa *d;
struct dfa *d2;
chr *mid;
int er;
assert(t->op == '.');
assert(t->left != NULL && t->left->cnfa.nstates > 0);
assert(t->right != NULL && t->right->cnfa.nstates > 0);
assert(t->left->flags & SHORTER);
/* concatenation -- need to split the substring between parts */
d = newdfa(v, &t->left->cnfa, &v->g->cmap, DOMALLOC);
if (ISERR())
return v->err;
d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, DOMALLOC);
if (ISERR())
{
freedfa(d);
return v->err;
}
MDEBUG(("crev %d\n", t->retry));
/* pick a tentative midpoint */
if (v->mem[t->retry] == 0)
{
mid = shortest(v, d, begin, begin, end, (chr **) NULL, (int *) NULL);
if (mid == NULL)
{
freedfa(d);
freedfa(d2);
return REG_NOMATCH;
}
MDEBUG(("tentative midpoint %ld\n", LOFF(mid)));
v->mem[t->retry] = (mid - begin) + 1;
}
else
{
mid = begin + (v->mem[t->retry] - 1);
MDEBUG(("working midpoint %ld\n", LOFF(mid)));
}
/* iterate until satisfaction or failure */
for (;;)
{
/* try this midpoint on for size */
if (longest(v, d2, mid, end, (int *) NULL) == end)
{
er = cdissect(v, t->left, begin, mid);
if (er == REG_OKAY)
{
er = cdissect(v, t->right, mid, end);
if (er == REG_OKAY)
{
/* satisfaction */
MDEBUG(("successful\n"));
freedfa(d);
freedfa(d2);
return REG_OKAY;
}
}
if (er != REG_OKAY && er != REG_NOMATCH)
{
freedfa(d);
freedfa(d2);
return er;
}
}
/* that midpoint didn't work, find a new one */
if (mid == end)
{
/* all possibilities exhausted */
MDEBUG(("%d no midpoint\n", t->retry));
freedfa(d);
freedfa(d2);
return REG_NOMATCH;
}
mid = shortest(v, d, begin, mid + 1, end, (chr **) NULL, (int *) NULL);
if (mid == NULL)
{
/* failed to find a new one */
MDEBUG(("%d failed midpoint\n", t->retry));
freedfa(d);
freedfa(d2);
return REG_NOMATCH;
}
MDEBUG(("%d: new midpoint %ld\n", t->retry, LOFF(mid)));
v->mem[t->retry] = (mid - begin) + 1;
zapmem(v, t->left);
zapmem(v, t->right);
}
/* can't get here */
return REG_ASSERT;
}
/*
* cbrdissect - determine backref subexpression matches
*/
static int /* regexec return code */
cbrdissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
int i;
int n = t->subno;
size_t len;
chr *paren;
chr *p;
chr *stop;
int min = t->min;
int max = t->max;
assert(t != NULL);
assert(t->op == 'b');
assert(n >= 0);
assert((size_t) n < v->nmatch);
MDEBUG(("cbackref n%d %d{%d-%d}\n", t->retry, n, min, max));
if (v->pmatch[n].rm_so == -1)
return REG_NOMATCH;
paren = v->start + v->pmatch[n].rm_so;
len = v->pmatch[n].rm_eo - v->pmatch[n].rm_so;
/* no room to maneuver -- retries are pointless */
if (v->mem[t->retry])
return REG_NOMATCH;
v->mem[t->retry] = 1;
/* special-case zero-length string */
if (len == 0)
{
if (begin == end)
return REG_OKAY;
return REG_NOMATCH;
}
/* and too-short string */
assert(end >= begin);
if ((size_t) (end - begin) < len)
return REG_NOMATCH;
stop = end - len;
/* count occurrences */
i = 0;
for (p = begin; p <= stop && (i < max || max == INFINITY); p += len)
{
if ((*v->g->compare) (paren, p, len) != 0)
break;
i++;
}
MDEBUG(("cbackref found %d\n", i));
/* and sort it out */
if (p != end) /* didn't consume all of it */
return REG_NOMATCH;
if (min <= i && (i <= max || max == INFINITY))
return REG_OKAY;
return REG_NOMATCH; /* out of range */
}
/*
* caltdissect - determine alternative subexpression matches (w. complications)
*/
static int /* regexec return code */
caltdissect(struct vars * v,
struct subre * t,
chr *begin, /* beginning of relevant substring */
chr *end) /* end of same */
{
struct dfa *d;
int er;
#define UNTRIED 0 /* not yet tried at all */
#define TRYING 1 /* top matched, trying submatches */
#define TRIED 2 /* top didn't match or submatches exhausted */
if (t == NULL)
return REG_NOMATCH;
assert(t->op == '|');
if (v->mem[t->retry] == TRIED)
return caltdissect(v, t->right, begin, end);
MDEBUG(("calt n%d\n", t->retry));
assert(t->left != NULL);
if (v->mem[t->retry] == UNTRIED)
{
d = newdfa(v, &t->left->cnfa, &v->g->cmap, DOMALLOC);
if (ISERR())
return v->err;
if (longest(v, d, begin, end, (int *) NULL) != end)
{
freedfa(d);
v->mem[t->retry] = TRIED;
return caltdissect(v, t->right, begin, end);
}
freedfa(d);
MDEBUG(("calt matched\n"));
v->mem[t->retry] = TRYING;
}
er = cdissect(v, t->left, begin, end);
if (er != REG_NOMATCH)
return er;
v->mem[t->retry] = TRIED;
return caltdissect(v, t->right, begin, end);
}
#include "rege_dfa.c"
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