common/regex/regnexec.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1985-2010 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped

/*
 * posix regex executor
 * single sized-record interface
 */

#include "reglib.h"

#if _AST_REGEX_DEBUG

#define DEBUG_TEST(f,y,n)   ((debug&(debug_flag=f))?(y):(n))
#define DEBUG_CODE(f,y,n)   do if(debug&(f)){y}else{n} while(0)
#define DEBUG_INIT()        do { char* t; if (!debug) { debug = 0x80000000; if (t = getenv("_AST_regex_exec_debug")) debug |= strtoul(t, NiL, 0); } } while (0)

static unsigned long    debug;
static unsigned long    debug_flag;

static const char*  rexnames[] =
{
    "REX_NULL",
    "REX_ALT",
    "REX_ALT_CATCH",
    "REX_BACK",
    "REX_BEG",
    "REX_BEG_STR",
    "REX_BM",
    "REX_CAT",
    "REX_CLASS",
    "REX_COLL_CLASS",
    "REX_CONJ",
    "REX_CONJ_LEFT",
    "REX_CONJ_RIGHT",
    "REX_DONE",
    "REX_DOT",
    "REX_END",
    "REX_END_STR",
    "REX_EXEC",
    "REX_FIN_STR",
    "REX_GROUP",
    "REX_GROUP_CATCH",
    "REX_GROUP_AHEAD",
    "REX_GROUP_AHEAD_CATCH",
    "REX_GROUP_AHEAD_NOT",
    "REX_GROUP_BEHIND",
    "REX_GROUP_BEHIND_CATCH",
    "REX_GROUP_BEHIND_NOT",
    "REX_GROUP_BEHIND_NOT_CATCH",
    "REX_GROUP_COND",
    "REX_GROUP_COND_CATCH",
    "REX_GROUP_CUT",
    "REX_GROUP_CUT_CATCH",
    "REX_KMP",
    "REX_NEG",
    "REX_NEG_CATCH",
    "REX_NEST",
    "REX_ONECHAR",
    "REX_REP",
    "REX_REP_CATCH",
    "REX_STRING",
    "REX_TRIE",
    "REX_WBEG",
    "REX_WEND",
    "REX_WORD",
    "REX_WORD_NOT"
};

static const char* rexname(Rex_t* rex)
{
    if (!rex)
        return "NIL";
    if (rex->type >= elementsof(rexnames))
        return "ERROR";
    return rexnames[rex->type];
}

#else

#define DEBUG_INIT()
#define DEBUG_TEST(f,y,n)   (n)
#define DEBUG_CODE(f,y,n)   do {n} while(0)

#endif

#define BEG_ALT     1   /* beginning of an alt          */
#define BEG_ONE     2   /* beginning of one iteration of a rep  */
#define BEG_REP     3   /* beginning of a repetition        */
#define BEG_SUB     4   /* beginning of a subexpression     */
#define END_ANY     5   /* end of any of above          */

/*
 * returns from parse()
 */

#define NONE        0   /* no parse found           */
#define GOOD        1   /* some parse was found         */
#define CUT     2   /* no match and no backtrack        */
#define BEST        3   /* an unbeatable parse was found    */
#define BAD     4   /* error ocurred            */

/*
 * REG_SHELL_DOT test
 */

#define LEADING(e,r,s)  (*(s)==(e)->leading&&((s)==(e)->beg||*((s)-1)==(r)->explicit))

/*
 * Pos_t is for comparing parses. An entry is made in the
 * array at the beginning and at the end of each Group_t,
 * each iteration in a Group_t, and each Binary_t.
 */

typedef struct
{
    unsigned char*  p;      /* where in string      */
    size_t      length;     /* length in string     */
    short       serial;     /* preorder subpattern number   */
    short       be;     /* which end of pair        */
} Pos_t;

/* ===== begin library support ===== */

#define vector(t,v,i)   (((i)<(v)->max)?(t*)((v)->vec+(i)*(v)->siz):(t*)vecseek(&(v),i))

static Vector_t*
vecopen(int inc, int siz)
{
    Vector_t*   v;
    Stk_t*      sp;

    if (inc <= 0)
        inc = 16;
    if (!(sp = stkopen(STK_SMALL|STK_NULL)))
        return 0;
    if (!(v = (Vector_t*)stkseek(sp, sizeof(Vector_t) + inc * siz)))
    {
        stkclose(sp);
        return 0;
    }
    v->stk = sp;
    v->vec = (char*)v + sizeof(Vector_t);
    v->max = v->inc = inc;
    v->siz = siz;
    v->cur = 0;
    return v;
}

static void*
vecseek(Vector_t** p, int index)
{
    Vector_t*   v = *p;

    if (index >= v->max)
    {
        while ((v->max += v->inc) <= index);
        if (!(v = (Vector_t*)stkseek(v->stk, sizeof(Vector_t) + v->max * v->siz)))
            return 0;
        *p = v;
        v->vec = (char*)v + sizeof(Vector_t);
    }
    return v->vec + index * v->siz;
}

static void
vecclose(Vector_t* v)
{
    if (v)
        stkclose(v->stk);
}

typedef struct
{
    Stk_pos_t   pos;
    char        data[1];
} Stk_frame_t;

#define stknew(s,p) ((p)->offset=stktell(s),(p)->base=stkfreeze(s,0))
#define stkold(s,p) stkset(s,(p)->base,(p)->offset)

#define stkframe(s) (*((Stk_frame_t**)stktop(s)-1))
#define stkdata(s,t)    ((t*)stkframe(s)->data)
#define stkpop(s)   stkold(s,&(stkframe(s)->pos))

static void*
stkpush(Stk_t* sp, size_t size)
{
    Stk_frame_t*    f;
    Stk_pos_t   p;

    stknew(sp, &p);
    size = sizeof(Stk_frame_t) + sizeof(size_t) + size - 1;
    if (!(f = (Stk_frame_t*)stkalloc(sp, sizeof(Stk_frame_t) + sizeof(Stk_frame_t*) + size - 1)))
        return 0;
    f->pos = p;
    stkframe(sp) = f;
    return f->data;
}

/* ===== end library support ===== */

/*
 * Match_frame_t is for saving and restoring match records
 * around alternate attempts, so that fossils will not be
 * left in the match array.  These are the only entries in
 * the match array that are not otherwise guaranteed to
 * have current data in them when they get used.
 */

typedef struct
{
    size_t          size;
    regmatch_t*     match;
    regmatch_t      save[1];
} Match_frame_t;

#define matchframe  stkdata(stkstd,Match_frame_t)
#define matchpush(e,x)  ((x)->re.group.number?_matchpush(e,x):0)
#define matchcopy(e,x)  ((x)->re.group.number?memcpy(matchframe->match,matchframe->save,matchframe->size):(void*)0)
#define matchpop(e,x)   ((x)->re.group.number?memcpy(matchframe->match,matchframe->save,matchframe->size),stkpop(stkstd):(void*)0)

#define pospop(e)   (--(e)->pos->cur)

/*
 * allocate a frame and push a match onto the stack
 */

static int
_matchpush(Env_t* env, Rex_t* rex)
{
    Match_frame_t*  f;
    regmatch_t* m;
    regmatch_t* e;
    regmatch_t* s;
    int     num;

    if (rex->re.group.number <= 0 || (num = rex->re.group.last - rex->re.group.number + 1) <= 0)
        num = 0;
    if (!(f = (Match_frame_t*)stkpush(stkstd, sizeof(Match_frame_t) + (num - 1) * sizeof(regmatch_t))))
    {
        env->error = REG_ESPACE;
        return 1;
    }
    f->size = num * sizeof(regmatch_t);
    f->match = m = env->match + rex->re.group.number;
    e = m + num;
    s = f->save;
    while (m < e)
    {
        *s++ = *m;
        *m++ = state.nomatch;
    }
    return 0;
}

/*
 * allocate a frame and push a pos onto the stack
 */

static int
pospush(Env_t* env, Rex_t* rex, unsigned char* p, int be)
{
    Pos_t*  pos;

    if (!(pos = vector(Pos_t, env->pos, env->pos->cur)))
    {
        env->error = REG_ESPACE;
        return 1;
    }
    pos->serial = rex->serial;
    pos->p = p;
    pos->be = be;
    env->pos->cur++;
    return 0;
}

/*
 * two matches are known to have the same length
 * os is start of old pos array, ns is start of new,
 * oend and nend are end+1 pointers to ends of arrays.
 * oe and ne are ends (not end+1) of subarrays.
 * returns 1 if new is better, -1 if old, else 0.
 */

static int
better(Env_t* env, Pos_t* os, Pos_t* ns, Pos_t* oend, Pos_t* nend, int level)
{
    Pos_t*  oe;
    Pos_t*  ne;
    int k;
    int n;

    if (env->error)
        return -1;
    for (;;)
    {
        DEBUG_CODE(0x0080,{sfprintf(sfstdout, "   %-*.*sold ", (level + 3) * 4, (level + 3) * 4, "");for (oe = os; oe < oend; oe++)sfprintf(sfstdout, "<%d,%d,%d>", oe->p - env->beg, oe->serial, oe->be);sfprintf(sfstdout, "\n   %-*.*snew ", (level + 3) * 4, (level + 3) * 4, "");for (oe = ns; oe < nend; oe++)sfprintf(sfstdout, "<%d,%d,%d>", oe->p - env->beg, oe->serial, oe->be);sfprintf(sfstdout, "\n");},{0;});
        if (ns >= nend)
            return DEBUG_TEST(0x8000,(os < oend),(0));
        if (os >= oend)
            return DEBUG_TEST(0x8000,(-1),(1));
        n = os->serial;
        if (ns->serial > n)
            return -1;
        if (n > ns->serial)
        {
            env->error = REG_PANIC;
            return -1;
        }
        if (ns->p > os->p)
            return 1;
        if (os->p > ns->p)
            return -1;
        oe = os;
        k = 0;
        for (;;)
            if ((++oe)->serial == n)
            {
                if (oe->be != END_ANY)
                    k++;
                else if (k-- <= 0)
                    break;
            }
        ne = ns;
        k = 0;
        for (;;)
            if ((++ne)->serial == n)
            {
                if (ne->be != END_ANY)
                    k++;
                else if (k-- <= 0)
                    break;
            }
        if (ne->p > oe->p)
            return 1;
        if (oe->p > ne->p)
            return -1;
        if (k = better(env, os + 1, ns + 1, oe, ne, level + 1))
            return k;
        os = oe + 1;
        ns = ne + 1;
    }
}

#if _AST_REGEX_DEBUG

static void
showmatch(regmatch_t* p)
{
    sfputc(sfstdout, '(');
    if (p->rm_so < 0)
        sfputc(sfstdout, '?');
    else
        sfprintf(sfstdout, "%d", p->rm_so);
    sfputc(sfstdout, ',');
    if (p->rm_eo < 0)
        sfputc(sfstdout, '?');
    else
        sfprintf(sfstdout, "%d", p->rm_eo);
    sfputc(sfstdout, ')');
}

static int
_better(Env_t* env, Pos_t* os, Pos_t* ns, Pos_t* oend, Pos_t* nend, int level)
{
    int i;

    DEBUG_CODE(0x0040,{sfprintf(sfstdout, "AHA better old ");for (i = 0; i <= env->nsub; i++)showmatch(&env->best[i]);sfprintf(sfstdout, "\n           new ");for (i = 0; i <= env->nsub; i++)showmatch(&env->match[i]);sfprintf(sfstdout, "\n");},{0;});
    i = better(env, os, ns, oend, nend, 0);
    DEBUG_TEST(0x0040,(sfprintf(sfstdout, "           %s\n", i <= 0 ? "OLD" : "NEW")),(0));
    return i;
}

#define better  _better

#endif

#define follow(e,r,c,s) ((r)->next?parse(e,(r)->next,c,s):(c)?parse(e,c,0,s):BEST)

static int      parse(Env_t*, Rex_t*, Rex_t*, unsigned char*);

static int
parserep(Env_t* env, Rex_t* rex, Rex_t* cont, unsigned char* s, int n)
{
    int i;
    int r = NONE;
    Rex_t   catcher;

    DEBUG_TEST(0x0010,(sfprintf(sfstdout, "AHA#%04d 0x%04x parserep %s %d %d %d %d `%-.*s'\n", __LINE__, debug_flag, rexname(rex->re.group.expr.rex), rex->re.group.number, rex->lo, n, rex->hi, env->end - s, s)),(0));
    if ((rex->flags & REG_MINIMAL) && n >= rex->lo && n < rex->hi)
    {
        if (env->stack && pospush(env, rex, s, END_ANY))
            return BAD;
        i = follow(env, rex, cont, s);
        if (env->stack)
            pospop(env);
        switch (i)
        {
        case BAD:
            return BAD;
        case CUT:
            return CUT;
        case BEST:
        case GOOD:
            return BEST;
        }
    }
    if (n < rex->hi)
    {
        catcher.type = REX_REP_CATCH;
        catcher.serial = rex->serial;
        catcher.re.rep_catch.ref = rex;
        catcher.re.rep_catch.cont = cont;
        catcher.re.rep_catch.beg = s;
        catcher.re.rep_catch.n = n + 1;
        catcher.next = rex->next;
        if (n == 0)
            rex->re.rep_catch.beg = s;
        if (env->stack)
        {
            if (matchpush(env, rex))
                return BAD;
            if (pospush(env, rex, s, BEG_ONE))
                return BAD;
DEBUG_TEST(0x0004,(sfprintf(sfstdout,"AHA#%04d 0x%04x PUSH %d   (%d,%d)(%d,%d)(%d,%d) (%d,%d)(%d,%d)(%d,%d)\n", __LINE__, debug_flag, rex->re.group.number, env->best[0].rm_so, env->best[0].rm_eo, env->best[1].rm_so, env->best[1].rm_eo, env->best[2].rm_so, env->best[2].rm_eo, env->match[0].rm_so, env->match[0].rm_eo, env->match[1].rm_so, env->match[1].rm_eo, env->match[2].rm_so, env->match[2].rm_eo)),(0));
        }
        r = parse(env, rex->re.group.expr.rex, &catcher, s);
        DEBUG_TEST(0x0010,(sfprintf(sfstdout, "AHA#%04d 0x%04x parserep parse %d %d `%-.*s'\n", __LINE__, debug_flag, rex->re.group.number, r, env->end - s, s)),(0));
        if (env->stack)
        {
            pospop(env);
            matchpop(env, rex);
DEBUG_TEST(0x0004,(sfprintf(sfstdout,"AHA#%04d 0x%04x POP  %d %d (%d,%d)(%d,%d)(%d,%d) (%d,%d)(%d,%d)(%d,%d)\n", __LINE__, debug_flag, rex->re.group.number, r, env->best[0].rm_so, env->best[0].rm_eo, env->best[1].rm_so, env->best[1].rm_eo, env->best[2].rm_so, env->best[2].rm_eo, env->match[0].rm_so, env->match[0].rm_eo, env->match[1].rm_so, env->match[1].rm_eo, env->match[2].rm_so, env->match[2].rm_eo)),(0));
        }
        switch (r)
        {
        case BAD:
            return BAD;
        case BEST:
            return BEST;
        case CUT:
            r = NONE;
            break;
        case GOOD:
            if (rex->flags & REG_MINIMAL)
                return BEST;
            r = GOOD;
            break;
        }
    }
    if (n < rex->lo)
        return r;
    if (!(rex->flags & REG_MINIMAL) || n >= rex->hi)
    {
        if (env->stack && pospush(env, rex, s, END_ANY))
            return BAD;
        i = follow(env, rex, cont, s);
        if (env->stack)
            pospop(env);
        switch (i)
        {
        case BAD:
            r = BAD;
            break;
        case CUT:
            r = CUT;
            break;
        case BEST:
            r = BEST;
            break;
        case GOOD:
            r = (rex->flags & REG_MINIMAL) ? BEST : GOOD;
            break;
        }
    }
    return r;
}

static int
parsetrie(Env_t* env, Trie_node_t* x, Rex_t* rex, Rex_t* cont, unsigned char* s)
{
    unsigned char*  p;
    int     r;

    if (p = rex->map)
    {
        for (;;)
        {
            if (s >= env->end)
                return NONE;
            while (x->c != p[*s])
                if (!(x = x->sib))
                    return NONE;
            if (x->end)
                break;
            x = x->son;
            s++;
        }
    }
    else
    {
        for (;;)
        {
            if (s >= env->end)
                return NONE;
            while (x->c != *s)
                if (!(x = x->sib))
                    return NONE;
            if (x->end)
                break;
            x = x->son;
            s++;
        }
    }
    s++;
    if (rex->flags & REG_MINIMAL)
        switch (follow(env, rex, cont, s))
        {
        case BAD:
            return BAD;
        case CUT:
            return CUT;
        case BEST:
        case GOOD:
            return BEST;
        }
    if (x->son)
        switch (parsetrie(env, x->son, rex, cont, s))
        {
        case BAD:
            return BAD;
        case CUT:
            return CUT;
        case BEST:
            return BEST;
        case GOOD:
            if (rex->flags & REG_MINIMAL)
                return BEST;
            r = GOOD;
            break;
        default:
            r = NONE;
            break;
        }
    else
        r = NONE;
    if (!(rex->flags & REG_MINIMAL))
        switch (follow(env, rex, cont, s))
        {
        case BAD:
            return BAD;
        case CUT:
            return CUT;
        case BEST:
            return BEST;
        case GOOD:
            return GOOD;
    }
    return r;
}

static int
collelt(register Celt_t* ce, char* key, int c, int x)
{
    Ckey_t  elt;

    mbxfrm(elt, key, COLL_KEY_MAX);
    for (;; ce++)
    {
        switch (ce->typ)
        {
        case COLL_call:
            if (!x && (*ce->fun)(c))
                return 1;
            continue;
        case COLL_char:
            if (!strcmp((char*)ce->beg, (char*)elt))
                return 1;
            continue;
        case COLL_range:
            if (strcmp((char*)ce->beg, (char*)elt) <= ce->min && strcmp((char*)elt, (char*)ce->end) <= ce->max)
                return 1;
            continue;
        case COLL_range_lc:
            if (strcmp((char*)ce->beg, (char*)elt) <= ce->min && strcmp((char*)elt, (char*)ce->end) <= ce->max && (iswlower(c) || !iswupper(c)))
                return 1;
            continue;
        case COLL_range_uc:
            if (strcmp((char*)ce->beg, (char*)elt) <= ce->min && strcmp((char*)elt, (char*)ce->end) <= ce->max && (iswupper(c) || !iswlower(c)))
                return 1;
            continue;
        }
        break;
    }
    return 0;
}

static int
collic(register Celt_t* ce, char* key, register char* nxt, int c, int x)
{
    if (!x)
    {
        if (collelt(ce, key, c, x))
            return 1;
        if (iswlower(c))
            c = towupper(c);
        else if (iswupper(c))
            c = towlower(c);
        else
            return 0;
        x = mbconv(key, c);
        key[x] = 0;
        return collelt(ce, key, c, 0);
    }
    while (*nxt)
    {
        if (collic(ce, key, nxt + 1, c, x))
            return 1;
        if (islower(*nxt))
            *nxt = toupper(*nxt);
        else if (isupper(*nxt))
            *nxt = tolower(*nxt);
        else
            return 0;
        nxt++;
    }
    return collelt(ce, key, c, x);
}

static int
collmatch(Rex_t* rex, unsigned char* s, unsigned char* e, unsigned char** p)
{
    unsigned char*      t;
    wchar_t         c;
    int         w;
    int         r;
    int         x;
    int         ic;
    Ckey_t          key;
    Ckey_t          elt;

    ic = (rex->flags & REG_ICASE);
    if ((w = MBSIZE(s)) > 1)
    {
        memcpy((char*)key, (char*)s, w);
        key[w] = 0;
        t = s;
        c = mbchar(t);
#if !_lib_wctype
        c &= 0xff;
#endif
        x = 0;
    }
    else
    {
        c = s[0];
        if (ic && isupper(c))
            c = tolower(c);
        key[0] = c;
        key[1] = 0;
        if (isalpha(c))
        {
            x = e - s;
            if (x > COLL_KEY_MAX)
                x = COLL_KEY_MAX;
            while (w < x)
            {
                c = s[w];
                if (!isalpha(c))
                    break;
                r = mbxfrm(elt, key, COLL_KEY_MAX);
                if (ic && isupper(c))
                    c = tolower(c);
                key[w] = c;
                key[w + 1] = 0;
                if (mbxfrm(elt, key, COLL_KEY_MAX) != r)
                    break;
                w++;
            }
        }
        key[w] = 0;
        c = key[0];
        x = w - 1;
    }
    r = 1;
    for (;;)
    {
        if (ic ? collic(rex->re.collate.elements, (char*)key, (char*)key, c, x) : collelt(rex->re.collate.elements, (char*)key, c, x))
            break;
        if (!x)
        {
            r = 0;
            break;
        }
        w = x--;
        key[w] = 0;
    }
    *p = s + w;
    return rex->re.collate.invert ? !r : r;
}

static unsigned char*
nestmatch(register unsigned char* s, register unsigned char* e, const unsigned short* type, register int co)
{
    register int    c;
    register int    cc;
    unsigned int    n;
    int     oc;

    if (type[co] & (REX_NEST_literal|REX_NEST_quote))
    {
        n = (type[co] & REX_NEST_literal) ? REX_NEST_terminator : (REX_NEST_escape|REX_NEST_terminator);
        while (s < e)
        {
            c = *s++;
            if (c == co)
                return s;
            else if (type[c] & n)
            {
                if (s >= e || (type[c] & REX_NEST_terminator))
                    break;
                s++;
            }
        }
    }
    else
    {
        cc = type[co] >> REX_NEST_SHIFT;
        oc = type[co] & (REX_NEST_open|REX_NEST_close);
        n = 1;
        while (s < e)
        {
            c = *s++;
            switch (type[c] & (REX_NEST_escape|REX_NEST_open|REX_NEST_close|REX_NEST_delimiter|REX_NEST_separator|REX_NEST_terminator))
            {
            case REX_NEST_delimiter:
            case REX_NEST_terminator:
                return oc ? 0 : s;
            case REX_NEST_separator:
                if (!oc)
                    return s;
                break;
            case REX_NEST_escape:
                if (s >= e)
                    return 0;
                s++;
                break;
            case REX_NEST_open|REX_NEST_close:
                if (c == cc)
                {
                    if (!--n)
                        return s;
                }
                /*FALLTHROUGH*/
            case REX_NEST_open:
                if (c == co)
                {
                    if (!++n)
                        return 0;
                }
                else if (!(s = nestmatch(s, e, type, c)))
                    return 0;
                break;
            case REX_NEST_close:
                if (c != cc)
                    return 0;
                if (!--n)
                    return s;
                break;
            }
        }
        return (oc || !(type[UCHAR_MAX+1] & REX_NEST_terminator)) ? 0 : s;
    }
    return 0;
}

static int
parse(Env_t* env, Rex_t* rex, Rex_t* cont, unsigned char* s)
{
    int     c;
    int     d;
    int     i;
    int     m;
    int     n;
    int     r;
    int*        f;
    unsigned char*  p;
    unsigned char*  t;
    unsigned char*  b;
    unsigned char*  e;
    char*       u;
    regmatch_t* o;
    Trie_node_t*    x;
    Rex_t*      q;
    Rex_t       catcher;
    Rex_t       next;

    for (;;)
    {
DEBUG_TEST(0x0008,(sfprintf(sfstdout, "AHA#%04d 0x%04x parse %s `%-.*s'\n", __LINE__, debug_flag, rexname(rex), env->end - s, s)),(0));
        switch (rex->type)
        {
        case REX_ALT:
            if (env->stack)
            {
                if (matchpush(env, rex))
                    return BAD;
                if (pospush(env, rex, s, BEG_ALT))
                    return BAD;
                catcher.type = REX_ALT_CATCH;
                catcher.serial = rex->serial;
                catcher.re.alt_catch.cont = cont;
                catcher.next = rex->next;
                r = parse(env, rex->re.group.expr.binary.left, &catcher, s);
                if (r < BEST || (rex->flags & REG_MINIMAL))
                {
                    matchcopy(env, rex);
                    ((Pos_t*)env->pos->vec + env->pos->cur - 1)->serial = catcher.serial = rex->re.group.expr.binary.serial;
                    n = parse(env, rex->re.group.expr.binary.right, &catcher, s);
                    if (n != NONE)
                        r = n;
                }
                pospop(env);
                matchpop(env, rex);
            }
            else
            {
                if ((r = parse(env, rex->re.group.expr.binary.left, cont, s)) == NONE)
                    r = parse(env, rex->re.group.expr.binary.right, cont, s);
                if (r == GOOD)
                    r = BEST;
            }
            return r;
        case REX_ALT_CATCH:
            if (pospush(env, rex, s, END_ANY))
                return BAD;
            r = follow(env, rex, rex->re.alt_catch.cont, s);
            pospop(env);
            return r;
        case REX_BACK:
            o = &env->match[rex->lo];
            if (o->rm_so < 0)
                return NONE;
            i = o->rm_eo - o->rm_so;
            e = s + i;
            if (e > env->end)
                return NONE;
            t = env->beg + o->rm_so;
            if (!(p = rex->map))
            {
                while (s < e)
                    if (*s++ != *t++)
                        return NONE;
            }
            else if (!mbwide())
            {
                while (s < e)
                    if (p[*s++] != p[*t++])
                        return NONE;
            }
            else
            {
                while (s < e)
                {
                    c = mbchar(s);
                    d = mbchar(t);
                    if (towupper(c) != towupper(d))
                        return NONE;
                }
            }
            break;
        case REX_BEG:
            if ((!(rex->flags & REG_NEWLINE) || s <= env->beg || *(s - 1) != '\n') && ((env->flags & REG_NOTBOL) || s != env->beg))
                return NONE;
            break;
        case REX_CLASS:
            if (LEADING(env, rex, s))
                return NONE;
            n = rex->hi;
            if (n > env->end - s)
                n = env->end - s;
            m = rex->lo;
            if (m > n)
                return NONE;
            r = NONE;
            if (!(rex->flags & REG_MINIMAL))
            {
                for (i = 0; i < n; i++)
                    if (!settst(rex->re.charclass, s[i]))
                    {
                        n = i;
                        break;
                    }
                for (s += n; n-- >= m; s--)
                    switch (follow(env, rex, cont, s))
                    {
                    case BAD:
                        return BAD;
                    case CUT:
                        return CUT;
                    case BEST:
                        return BEST;
                    case GOOD:
                        r = GOOD;
                        break;
                    }
            }
            else
            {
                for (e = s + m; s < e; s++)
                    if (!settst(rex->re.charclass, *s))
                        return r;
                e += n - m;
                for (;;)
                {
                    switch (follow(env, rex, cont, s))
                    {
                    case BAD:
                        return BAD;
                    case CUT:
                        return CUT;
                    case BEST:
                    case GOOD:
                        return BEST;
                    }
                    if (s >= e || !settst(rex->re.charclass, *s))
                        break;
                    s++;
                }
            }
            return r;
        case REX_COLL_CLASS:
            if (LEADING(env, rex, s))
                return NONE;
            n = rex->hi;
            if (n > env->end - s)
                n = env->end - s;
            m = rex->lo;
            if (m > n)
                return NONE;
            r = NONE;
            e = env->end;
            if (!(rex->flags & REG_MINIMAL))
            {
                if (!(b = (unsigned char*)stkpush(stkstd, n)))
                {
                    env->error = REG_ESPACE;
                    return BAD;
                }
                for (i = 0; s < e && i < n && collmatch(rex, s, e, &t); i++)
                {
                    b[i] = t - s;
                    s = t;
                }
                for (; i-- >= rex->lo; s -= b[i])
                    switch (follow(env, rex, cont, s))
                    {
                    case BAD:
                        stkpop(stkstd);
                        return BAD;
                    case CUT:
                        stkpop(stkstd);
                        return CUT;
                    case BEST:
                        stkpop(stkstd);
                        return BEST;
                    case GOOD:
                        r = GOOD;
                        break;
                    }
                stkpop(stkstd);
            }
            else
            {
                for (i = 0; i < m && s < e; i++, s = t)
                    if (!collmatch(rex, s, e, &t))
                        return r;
                while (i++ <= n)
                {
                    switch (follow(env, rex, cont, s))
                    {
                    case BAD:
                        return BAD;
                    case CUT:
                        return CUT;
                    case BEST:
                    case GOOD:
                        return BEST;
                    }
                    if (s >= e || !collmatch(rex, s, e, &s))
                        break;
                }
            }
            return r;
        case REX_CONJ:
            next.type = REX_CONJ_RIGHT;
            next.re.conj_right.cont = cont;
            next.next = rex->next;
            catcher.type = REX_CONJ_LEFT;
            catcher.re.conj_left.right = rex->re.group.expr.binary.right;
            catcher.re.conj_left.cont = &next;
            catcher.re.conj_left.beg = s;
            catcher.next = 0;
            return parse(env, rex->re.group.expr.binary.left, &catcher, s);
        case REX_CONJ_LEFT:
            rex->re.conj_left.cont->re.conj_right.end = s;
            cont = rex->re.conj_left.cont;
            s = rex->re.conj_left.beg;
            rex = rex->re.conj_left.right;
            continue;
        case REX_CONJ_RIGHT:
            if (rex->re.conj_right.end != s)
                return NONE;
            cont = rex->re.conj_right.cont;
            break;
        case REX_DONE:
            if (!env->stack)
                return BEST;
            n = s - env->beg;
            r = env->nsub;
            DEBUG_TEST(0x0100,(sfprintf(sfstdout,"AHA#%04d 0x%04x %s (%d,%d)(%d,%d)(%d,%d)(%d,%d) (%d,%d)(%d,%d)\n", __LINE__, debug_flag, rexname(rex), env->best[0].rm_so, env->best[0].rm_eo, env->best[1].rm_so, env->best[1].rm_eo, env->best[2].rm_so, env->best[2].rm_eo, env->best[3].rm_so, env->best[3].rm_eo, env->match[0].rm_so, env->match[0].rm_eo, env->match[1].rm_so, env->match[1].rm_eo)),(0));
            if ((i = env->best[0].rm_eo) >= 0)
            {
                if (rex->flags & REG_MINIMAL)
                {
                    if (n > i)
                        return GOOD;
                }
                else
                {
                    if (n < i)
                        return GOOD;
                }
                if (n == i && better(env,
                             (Pos_t*)env->bestpos->vec,
                             (Pos_t*)env->pos->vec,
                             (Pos_t*)env->bestpos->vec+env->bestpos->cur,
                             (Pos_t*)env->pos->vec+env->pos->cur,
                             0) <= 0)
                    return GOOD;
            }
            env->best[0].rm_eo = n;
            memcpy(&env->best[1], &env->match[1], r * sizeof(regmatch_t));
            n = env->pos->cur;
            if (!vector(Pos_t, env->bestpos, n))
            {
                env->error = REG_ESPACE;
                return BAD;
            }
            env->bestpos->cur = n;
            memcpy(env->bestpos->vec, env->pos->vec, n * sizeof(Pos_t));
            DEBUG_TEST(0x0100,(sfprintf(sfstdout,"AHA#%04d 0x%04x %s (%d,%d)(%d,%d)(%d,%d)(%d,%d) (%d,%d)(%d,%d)\n", __LINE__, debug_flag, rexname(rex), env->best[0].rm_so, env->best[0].rm_eo, env->best[1].rm_so, env->best[1].rm_eo, env->best[2].rm_so, env->best[2].rm_eo, env->best[3].rm_so, env->best[3].rm_eo, env->match[0].rm_so, env->match[0].rm_eo, env->match[1].rm_so, env->match[1].rm_eo)),(0));
            return GOOD;
        case REX_DOT:
            if (LEADING(env, rex, s))
                return NONE;
            n = rex->hi;
            if (n > env->end - s)
                n = env->end - s;
            m = rex->lo;
            if (m > n)
                return NONE;
            if ((c = rex->explicit) >= 0 && !mbwide())
                for (i = 0; i < n; i++)
                    if (s[i] == c)
                    {
                        n = i;
                        break;
                    }
            r = NONE;
            if (!(rex->flags & REG_MINIMAL))
            {
                if (!mbwide())
                {
                    for (s += n; n-- >= m; s--)
                        switch (follow(env, rex, cont, s))
                        {
                        case BAD:
                            return BAD;
                        case CUT:
                            return CUT;
                        case BEST:
                            return BEST;
                        case GOOD:
                            r = GOOD;
                            break;
                        }
                }
                else
                {
                    if (!(b = (unsigned char*)stkpush(stkstd, n)))
                    {
                        env->error = REG_ESPACE;
                        return BAD;
                    }
                    e = env->end;
                    for (i = 0; s < e && i < n && *s != c; i++)
                        s += b[i] = MBSIZE(s);
                    for (; i-- >= m; s -= b[i])
                        switch (follow(env, rex, cont, s))
                        {
                        case BAD:
                            stkpop(stkstd);
                            return BAD;
                        case CUT:
                            stkpop(stkstd);
                            return CUT;
                        case BEST:
                            stkpop(stkstd);
                            return BEST;
                        case GOOD:
                            r = GOOD;
                            break;
                        }
                    stkpop(stkstd);
                }
            }
            else
            {
                if (!mbwide())
                {
                    e = s + n;
                    for (s += m; s <= e; s++)
                        switch (follow(env, rex, cont, s))
                        {
                        case BAD:
                            return BAD;
                        case CUT:
                            return CUT;
                        case BEST:
                        case GOOD:
                            return BEST;
                        }
                }
                else
                {
                    e = env->end;
                    for (i = 0; s < e && i < m && *s != c; i++)
                        s += MBSIZE(s);
                    if (i >= m)
                        for (; s <= e && i <= n; s += MBSIZE(s), i++)
                            switch (follow(env, rex, cont, s))
                            {
                            case BAD:
                                return BAD;
                            case CUT:
                                return CUT;
                            case BEST:
                            case GOOD:
                                return BEST;
                            }
                }
            }
            return r;
        case REX_END:
            if ((!(rex->flags & REG_NEWLINE) || *s != '\n') && ((env->flags & REG_NOTEOL) || s < env->end))
                return NONE;
            break;
        case REX_GROUP:
DEBUG_TEST(0x0200,(sfprintf(sfstdout,"AHA#%04d 0x%04x parse %s `%-.*s'\n", __LINE__, debug_flag, rexname(rex), env->end - s, s)),(0));
            if (env->stack)
            {
                if (rex->re.group.number)
                    env->match[rex->re.group.number].rm_so = s - env->beg;
                if (pospush(env, rex, s, BEG_SUB))
                    return BAD;
                catcher.re.group_catch.eo = rex->re.group.number ? &env->match[rex->re.group.number].rm_eo : (regoff_t*)0;
            }
            catcher.type = REX_GROUP_CATCH;
            catcher.serial = rex->serial;
            catcher.re.group_catch.cont = cont;
            catcher.next = rex->next;
            r = parse(env, rex->re.group.expr.rex, &catcher, s);
            if (env->stack)
            {
                pospop(env);
                if (rex->re.group.number)
                    env->match[rex->re.group.number].rm_so = -1;
            }
            return r;
        case REX_GROUP_CATCH:
DEBUG_TEST(0x0200,(sfprintf(sfstdout,"AHA#%04d 0x%04x parse %s=>%s `%-.*s'\n", __LINE__, debug_flag, rexname(rex), rexname(rex->re.group_catch.cont), env->end - s, s)),(0));
            if (env->stack)
            {
                if (rex->re.group_catch.eo)
                    *rex->re.group_catch.eo = s - env->beg;
                if (pospush(env, rex, s, END_ANY))
                    return BAD;
            }
            r = follow(env, rex, rex->re.group_catch.cont, s);
            if (env->stack)
            {
                pospop(env);
                if (rex->re.group_catch.eo)
                    *rex->re.group_catch.eo = -1;
            }
            return r;
        case REX_GROUP_AHEAD:
            catcher.type = REX_GROUP_AHEAD_CATCH;
            catcher.flags = rex->flags;
            catcher.serial = rex->serial;
            catcher.re.rep_catch.beg = s;
            catcher.re.rep_catch.cont = cont;
            catcher.next = rex->next;
            return parse(env, rex->re.group.expr.rex, &catcher, s);
        case REX_GROUP_AHEAD_CATCH:
            return follow(env, rex, rex->re.rep_catch.cont, rex->re.rep_catch.beg);
        case REX_GROUP_AHEAD_NOT:
            r = parse(env, rex->re.group.expr.rex, NiL, s);
            if (r == NONE)
                r = follow(env, rex, cont, s);
            else if (r != BAD)
                r = NONE;
            return r;
        case REX_GROUP_BEHIND:
            if ((s - env->beg) < rex->re.group.size)
                return NONE;
            catcher.type = REX_GROUP_BEHIND_CATCH;
            catcher.flags = rex->flags;
            catcher.serial = rex->serial;
            catcher.re.behind_catch.beg = s;
            catcher.re.behind_catch.end = e = env->end;
            catcher.re.behind_catch.cont = cont;
            catcher.next = rex->next;
            for (t = s - rex->re.group.size; t >= env->beg; t--)
            {
                env->end = s;
                r = parse(env, rex->re.group.expr.rex, &catcher, t);
                env->end = e;
                if (r != NONE)
                    return r;
            }
            return NONE;
        case REX_GROUP_BEHIND_CATCH:
            if (s != rex->re.behind_catch.beg)
                return NONE;
            env->end = rex->re.behind_catch.end;
            return follow(env, rex, rex->re.behind_catch.cont, rex->re.behind_catch.beg);
        case REX_GROUP_BEHIND_NOT:
            if ((s - env->beg) < rex->re.group.size)
                r = NONE;
            else
            {
                catcher.type = REX_GROUP_BEHIND_NOT_CATCH;
                catcher.re.neg_catch.beg = s;
                catcher.next = 0;
                e = env->end;
                env->end = s;
                for (t = s - rex->re.group.size; t >= env->beg; t--)
                {
                    r = parse(env, rex->re.group.expr.rex, &catcher, t);
                    if (r != NONE)
                        break;
                }
                env->end = e;
            }
            if (r == NONE)
                r = follow(env, rex, cont, s);
            else if (r != BAD)
                r = NONE;
            return r;
        case REX_GROUP_BEHIND_NOT_CATCH:
            return s == rex->re.neg_catch.beg ? GOOD : NONE;
        case REX_GROUP_COND:
            if (q = rex->re.group.expr.binary.right)
            {
                catcher.re.cond_catch.next[0] = q->re.group.expr.binary.right;
                catcher.re.cond_catch.next[1] = q->re.group.expr.binary.left;
            }
            else
                catcher.re.cond_catch.next[0] = catcher.re.cond_catch.next[1] = 0;
            if (q = rex->re.group.expr.binary.left)
            {
                catcher.type = REX_GROUP_COND_CATCH;
                catcher.flags = rex->flags;
                catcher.serial = rex->serial;
                catcher.re.cond_catch.yes = 0;
                catcher.re.cond_catch.beg = s;
                catcher.re.cond_catch.cont = cont;
                catcher.next = rex->next;
                r = parse(env, q, &catcher, s);
                if (r == BAD || catcher.re.cond_catch.yes)
                    return r;
            }
            else if (!rex->re.group.size || rex->re.group.size > 0 && env->match[rex->re.group.size].rm_so >= 0)
                r = GOOD;
            else
                r = NONE;
            if (q = catcher.re.cond_catch.next[r != NONE])
            {
                catcher.type = REX_CAT;
                catcher.flags = q->flags;
                catcher.serial = q->serial;
                catcher.re.group_catch.cont = cont;
                catcher.next = rex->next;
                return parse(env, q, &catcher, s);
            }
            return follow(env, rex, cont, s);
        case REX_GROUP_COND_CATCH:
            rex->re.cond_catch.yes = 1;
            catcher.type = REX_CAT;
            catcher.flags = rex->flags;
            catcher.serial = rex->serial;
            catcher.re.group_catch.cont = rex->re.cond_catch.cont;
            catcher.next = rex->next;
            return parse(env, rex->re.cond_catch.next[1], &catcher, rex->re.cond_catch.beg);
        case REX_CAT:
            return follow(env, rex, rex->re.group_catch.cont, s);
        case REX_GROUP_CUT:
            catcher.type = REX_GROUP_CUT_CATCH;
            catcher.flags = rex->flags;
            catcher.serial = rex->serial;
            catcher.re.group_catch.cont = cont;
            catcher.next = rex->next;
            return parse(env, rex->re.group.expr.rex, &catcher, s);
        case REX_GROUP_CUT_CATCH:
            switch (r = follow(env, rex, rex->re.group_catch.cont, s))
            {
            case GOOD:
                r = BEST;
                break;
            case NONE:
                r = CUT;
                break;
            }
            return r;
        case REX_KMP:
            f = rex->re.string.fail;
            b = rex->re.string.base;
            n = rex->re.string.size;
            t = s;
            e = env->end;
            if (p = rex->map)
            {
                while (t + n <= e)
                {
                    for (i = -1; t < e; t++)
                    {
                        while (i >= 0 && b[i+1] != p[*t])
                            i = f[i];
                        if (b[i+1] == p[*t])
                            i++;
                        if (i + 1 == n)
                        {
                            t++;
                            if (env->stack)
                                env->best[0].rm_so = t - s - n;
                            switch (follow(env, rex, cont, t))
                            {
                            case BAD:
                                return BAD;
                            case CUT:
                                return CUT;
                            case BEST:
                            case GOOD:
                                return BEST;
                            }
                            t -= n - 1;
                            break;
                        }
                    }
                }
            }
            else
            {
                while (t + n <= e)
                {
                    for (i = -1; t < e; t++)
                    {
                        while (i >= 0 && b[i+1] != *t)
                            i = f[i];
                        if (b[i+1] == *t)
                            i++;
                        if (i + 1 == n)
                        {
                            t++;
                            if (env->stack)
                                env->best[0].rm_so = t - s - n;
                            switch (follow(env, rex, cont, t))
                            {
                            case BAD:
                                return BAD;
                            case CUT:
                                return CUT;
                            case BEST:
                            case GOOD:
                                return BEST;
                            }
                            t -= n - 1;
                            break;
                        }
                    }
                }
            }
            return NONE;
        case REX_NEG:
            if (LEADING(env, rex, s))
                return NONE;
            i = env->end - s;
            n = ((i + 7) >> 3) + 1;
            catcher.type = REX_NEG_CATCH;
            catcher.re.neg_catch.beg = s;
            if (!(p = (unsigned char*)stkpush(stkstd, n)))
                return BAD;
            memset(catcher.re.neg_catch.index = p, 0, n);
            catcher.next = rex->next;
            if (parse(env, rex->re.group.expr.rex, &catcher, s) == BAD)
                r = BAD;
            else
            {
                r = NONE;
                for (; i >= 0; i--)
                    if (!bittst(p, i))
                    {
                        switch (follow(env, rex, cont, s + i))
                        {
                        case BAD:
                            r = BAD;
                            break;
                        case BEST:
                            r = BEST;
                            break;
                        case CUT:
                            r = CUT;
                            break;
                        case GOOD:
                            r = GOOD;
                            /*FALLTHROUGH*/
                        default:
                            continue;
                        }
                        break;
                    }
            }
            stkpop(stkstd);
            return r;
        case REX_NEG_CATCH:
            bitset(rex->re.neg_catch.index, s - rex->re.neg_catch.beg);
            return NONE;
        case REX_NEST:
            if (s >= env->end)
                return NONE;
            do
            {
                if ((c = *s++) == rex->re.nest.primary)
                {
                    if (s >= env->end || !(s = nestmatch(s, env->end, rex->re.nest.type, c)))
                        return NONE;
                    break;
                }
                if (rex->re.nest.primary >= 0)
                    return NONE;
                    if (rex->re.nest.type[c] & (REX_NEST_delimiter|REX_NEST_separator|REX_NEST_terminator))
                    break;
                    if (!(s = nestmatch(s, env->end, rex->re.nest.type, c)))
                    return NONE;
            } while (s < env->end && !(rex->re.nest.type[*(s-1)] & (REX_NEST_delimiter|REX_NEST_separator|REX_NEST_terminator)));
            break;
        case REX_NULL:
            break;
        case REX_ONECHAR:
            n = rex->hi;
            if (n > env->end - s)
                n = env->end - s;
            m = rex->lo;
            if (m > n)
                return NONE;
            r = NONE;
            c = rex->re.onechar;
            if (!(rex->flags & REG_MINIMAL))
            {
                if (!mbwide())
                {
                    if (p = rex->map)
                    {
                        for (i = 0; i < n; i++, s++)
                            if (p[*s] != c)
                                break;
                    }
                    else
                    {
                        for (i = 0; i < n; i++, s++)
                            if (*s != c)
                                break;
                    }
                    for (; i-- >= m; s--)
                        switch (follow(env, rex, cont, s))
                        {
                        case BAD:
                            return BAD;
                        case BEST:
                            return BEST;
                        case CUT:
                            return CUT;
                        case GOOD:
                            r = GOOD;
                            break;
                        }
                }
                else
                {
                    if (!(b = (unsigned char*)stkpush(stkstd, n)))
                    {
                        env->error = REG_ESPACE;
                        return BAD;
                    }
                    e = env->end;
                    if (!(rex->flags & REG_ICASE))
                    {
                        for (i = 0; s < e && i < n; i++, s = t)
                        {
                            t = s;
                            if (mbchar(t) != c)
                                break;
                            b[i] = t - s;
                        }
                    }
                    else
                    {
                        for (i = 0; s < e && i < n; i++, s = t)
                        {
                            t = s;
                            if (towupper(mbchar(t)) != c)
                                break;
                            b[i] = t - s;
                        }
                    }
                    for (; i-- >= m; s -= b[i])
                        switch (follow(env, rex, cont, s))
                        {
                        case BAD:
                            stkpop(stkstd);
                            return BAD;
                        case BEST:
                            stkpop(stkstd);
                            return BEST;
                        case CUT:
                            stkpop(stkstd);
                            return CUT;
                        case GOOD:
                            r = GOOD;
                            break;
                        }
                    stkpop(stkstd);
                }
            }
            else
            {
                if (!mbwide())
                {
                    e = s + m;
                    if (p = rex->map)
                    {
                        for (; s < e; s++)
                            if (p[*s] != c)
                                return r;
                        e += n - m;
                        for (;;)
                        {
                            switch (follow(env, rex, cont, s))
                            {
                            case BAD:
                                return BAD;
                            case CUT:
                                return CUT;
                            case BEST:
                            case GOOD:
                                return BEST;
                            }
                            if (s >= e || p[*s++] != c)
                                break;
                        }
                    }
                    else
                    {
                        for (; s < e; s++)
                            if (*s != c)
                                return r;
                        e += n - m;
                        for (;;)
                        {
                            switch (follow(env, rex, cont, s))
                            {
                            case BAD:
                                return BAD;
                            case CUT:
                                return CUT;
                            case BEST:
                            case GOOD:
                                return BEST;
                            }
                            if (s >= e || *s++ != c)
                                break;
                        }
                    }
                }
                else
                {
                    if (!(rex->flags & REG_ICASE))
                    {
                        for (i = 0; i < m && s < e; i++, s = t)
                        {
                            t = s;
                            if (mbchar(t) != c)
                                return r;
                        }
                        while (i++ <= n)
                        {
                            switch (follow(env, rex, cont, s))
                            {
                            case BAD:
                                return BAD;
                            case CUT:
                                return CUT;
                            case BEST:
                            case GOOD:
                                return BEST;
                            }
                            if (s >= e || mbchar(s) != c)
                                break;
                        }
                    }
                    else
                    {
                        for (i = 0; i < m && s < e; i++, s = t)
                        {
                            t = s;
                            if (towupper(mbchar(t)) != c)
                                return r;
                        }
                        while (i++ <= n)
                        {
                            switch (follow(env, rex, cont, s))
                            {
                            case BAD:
                                return BAD;
                            case CUT:
                                return CUT;
                            case BEST:
                            case GOOD:
                                return BEST;
                            }
                            if (s >= e || towupper(mbchar(s)) != c)
                                break;
                        }
                    }
                }
            }
            return r;
        case REX_REP:
            if (env->stack && pospush(env, rex, s, BEG_REP))
                return BAD;
            r = parserep(env, rex, cont, s, 0);
            if (env->stack)
                pospop(env);
            return r;
        case REX_REP_CATCH:
            DEBUG_TEST(0x0020,(sfprintf(sfstdout, "AHA#%04d 0x%04x %s n %d len %d s `%-.*s'\n", __LINE__, debug_flag, rexname(rex), rex->re.rep_catch.n, s - rex->re.rep_catch.beg, env->end - s, s)),(0));
            if (env->stack && pospush(env, rex, s, END_ANY))
                return BAD;
            if (s == rex->re.rep_catch.beg && rex->re.rep_catch.n > rex->re.rep_catch.ref->lo)
            {
                /*
                 * optional empty iteration
                 */

DEBUG_TEST(0x0002,(sfprintf(sfstdout, "AHA#%04d %p re.group.back=%d re.group.expr.rex=%s\n", __LINE__, rex->re.rep_catch.ref->re.group.expr.rex, rex->re.rep_catch.ref->re.group.expr.rex->re.group.back, rexname(rex->re.rep_catch.ref->re.group.expr.rex))),(0));
                if (!env->stack || s != rex->re.rep_catch.ref->re.rep_catch.beg && !rex->re.rep_catch.ref->re.group.expr.rex->re.group.back)
                    r = NONE;
                else if (pospush(env, rex, s, END_ANY))
                    r = BAD;
                else
                {
                    r = follow(env, rex, rex->re.rep_catch.cont, s);
                    pospop(env);
                }
            }
            else
                r = parserep(env, rex->re.rep_catch.ref, rex->re.rep_catch.cont, s, rex->re.rep_catch.n);
            if (env->stack)
                pospop(env);
            return r;
        case REX_STRING:
DEBUG_TEST(0x0200,(sfprintf(sfstdout,"AHA#%04d 0x%04x parse %s \"%-.*s\" `%-.*s'\n", __LINE__, debug_flag, rexname(rex), rex->re.string.size, rex->re.string.base, env->end - s, s)),(0));
            if (rex->re.string.size > (env->end - s))
                return NONE;
            t = rex->re.string.base;
            e = t + rex->re.string.size;
            if (!(p = rex->map))
            {
                while (t < e)
                    if (*s++ != *t++)
                        return NONE;
            }
            else if (!mbwide())
            {
                while (t < e)
                    if (p[*s++] != *t++)
                        return NONE;
            }
            else
            {
                while (t < e)
                {
                    c = mbchar(s);
                    d = mbchar(t);
                    if (towupper(c) != d)
                        return NONE;
                }
            }
            break;
        case REX_TRIE:
            if (((s + rex->re.trie.min) > env->end) || !(x = rex->re.trie.root[rex->map ? rex->map[*s] : *s]))
                return NONE;
            return parsetrie(env, x, rex, cont, s);
        case REX_EXEC:
            u = 0;
            r = (*env->disc->re_execf)(env->regex, rex->re.exec.data, rex->re.exec.text, rex->re.exec.size, (const char*)s, env->end - s, &u, env->disc);
            e = (unsigned char*)u;
            if (e >= s && e <= env->end)
                s = e;
            switch (r)
            {
            case 0:
                break;
            case REG_NOMATCH:
                return NONE;
            default:
                env->error = r;
                return BAD;
            }
            break;
        case REX_WBEG:
            if (!isword(*s) || s > env->beg && isword(*(s - 1)))
                return NONE;
            break;
        case REX_WEND:
            if (isword(*s) || s > env->beg && !isword(*(s - 1)))
                return NONE;
            break;
        case REX_WORD:
            if (s > env->beg && isword(*(s - 1)) == isword(*s))
                return NONE;
            break;
        case REX_WORD_NOT:
            if (s == env->beg || isword(*(s - 1)) != isword(*s))
                return NONE;
            break;
        case REX_BEG_STR:
            if (s != env->beg)
                return NONE;
            break;
        case REX_END_STR:
            for (t = s; t < env->end && *t == '\n'; t++);
            if (t < env->end)
                return NONE;
            break;
        case REX_FIN_STR:
            if (s < env->end)
                return NONE;
            break;
        }
        if (!(rex = rex->next))
        {
            if (!(rex = cont))
                break;
            cont = 0;
        }
    }
    return GOOD;
}

#if _AST_REGEX_DEBUG

static void
listnode(Rex_t* e, int level)
{
    int i;

    if (e)
    {
        do
        {
            for (i = 0; i < level; i++)
                sfprintf(sfstderr, "  ");
            sfprintf(sfstderr, "%s\n", rexname(e));
            switch (e->type)
            {
            case REX_ALT:
            case REX_CONJ:
                listnode(e->re.group.expr.binary.left, level + 1);
                listnode(e->re.group.expr.binary.right, level + 1);
                break;
            case REX_GROUP:
            case REX_GROUP_AHEAD:
            case REX_GROUP_AHEAD_NOT:
            case REX_GROUP_BEHIND:
            case REX_GROUP_BEHIND_NOT:
            case REX_GROUP_CUT:
            case REX_NEG:
            case REX_REP:
                listnode(e->re.group.expr.rex, level + 1);
                break;
            }
        } while (e = e->next);
    }
}

static int
list(Env_t* env, Rex_t* rex)
{
    sfprintf(sfstderr, "AHA regex hard=%d stack=%p\n", env->hard, env->stack);
    if (rex)
        listnode(rex, 1);
    return 0;
}

#endif

/*
 * returning REG_BADPAT or REG_ESPACE is not explicitly
 * countenanced by the standard
 */

int
regnexec(const regex_t* p, const char* s, size_t len, size_t nmatch, regmatch_t* match, regflags_t flags)
{
    register int    n;
    register int    i;
    int     j;
    int     k;
    int     m;
    int     advance;
    Env_t*      env;
    Rex_t*      e;

    DEBUG_INIT();
    DEBUG_TEST(0x0001,(sfprintf(sfstdout, "AHA#%04d 0x%04x regnexec %d 0x%08x `%-.*s'\n", __LINE__, debug_flag, nmatch, flags, len, s)),(0));
    if (!p || !(env = p->env))
        return REG_BADPAT;
    if (!s)
        return fatal(env->disc, REG_BADPAT, NiL);
    if (len < env->min)
    {
        DEBUG_TEST(0x0080,(sfprintf(sfstdout, "AHA#%04d REG_NOMATCH %d %d\n", __LINE__, len, env->min)),(0));
        return REG_NOMATCH;
    }
    env->regex = p;
    env->beg = (unsigned char*)s;
    env->end = env->beg + len;
    stknew(stkstd, &env->stk);
    env->flags &= ~REG_EXEC;
    env->flags |= (flags & REG_EXEC);
    advance = 0;
    if (env->stack = env->hard || !(env->flags & REG_NOSUB) && nmatch)
    {
        n = env->nsub;
        if (!(env->match = (regmatch_t*)stkpush(stkstd, 2 * (n + 1) * sizeof(regmatch_t))) ||
            !env->pos && !(env->pos = vecopen(16, sizeof(Pos_t))) ||
            !env->bestpos && !(env->bestpos = vecopen(16, sizeof(Pos_t))))
        {
            k = REG_ESPACE;
            goto done;
        }
        env->pos->cur = env->bestpos->cur = 0;
        env->best = &env->match[n + 1];
        env->best[0].rm_so = 0;
        env->best[0].rm_eo = -1;
        for (i = 0; i <= n; i++)
            env->match[i] = state.nomatch;
        if (flags & REG_ADVANCE)
            advance = 1;
    }
    DEBUG_TEST(0x1000,(list(env,env->rex)),(0));
    k = REG_NOMATCH;
    if ((e = env->rex)->type == REX_BM)
    {
        DEBUG_TEST(0x0080,(sfprintf(sfstdout, "AHA#%04d REX_BM\n", __LINE__)),(0));
        if (len < e->re.bm.right)
        {
            DEBUG_TEST(0x0080,(sfprintf(sfstdout, "AHA#%04d REG_NOMATCH %d %d\n", __LINE__, len, e->re.bm.right)),(0));
            goto done;
        }
        else if (!(flags & REG_LEFT))
        {
            register unsigned char* buf = (unsigned char*)s;
            register size_t     index = e->re.bm.left + e->re.bm.size;
            register size_t     mid = len - e->re.bm.right;
            register size_t*    skip = e->re.bm.skip;
            register size_t*    fail = e->re.bm.fail;
            register Bm_mask_t**    mask = e->re.bm.mask;
            Bm_mask_t       m;
            size_t          x;

            DEBUG_TEST(0x0080,(sfprintf(sfstdout, "AHA#%04d REX_BM len=%d right=%d left=%d size=%d %d %d\n", __LINE__, len, e->re.bm.right, e->re.bm.left, e->re.bm.size, index, mid)),(0));
            for (;;)
            {
                while ((index += skip[buf[index]]) < mid);
                if (index < HIT)
                {
                    DEBUG_TEST(0x0080,(sfprintf(sfstdout, "AHA#%04d REG_NOMATCH %d %d\n", __LINE__, index, HIT)),(0));
                    goto done;
                }
                index -= HIT;
                m = mask[n = e->re.bm.size - 1][buf[index]];
                do
                {
                    if (!n--)
                    {
                        if (e->re.bm.back < 0)
                            goto possible;
                        if (advance)
                        {
                            i = index - e->re.bm.back;
                            s += i;
                            if (env->stack)
                                env->best[0].rm_so += i;
                            goto possible;
                        }
                        x = index;
                        if (index < e->re.bm.back)
                            index = 0;
                        else
                            index -= e->re.bm.back;
                        while (index <= x)
                        {
                            if ((i = parse(env, e->next, &env->done, buf + index)) != NONE)
                            {
                                if (env->stack)
                                    env->best[0].rm_so = index;
                                n = env->nsub;
                                goto hit;
                            }
                            index++;
                        }
                        index += e->re.bm.size;
                        break;
                    }
                } while (m &= mask[n][buf[--index]]);
                if ((index += fail[n + 1]) >= len)
                    goto done;
            }
        }
 possible:
        n = env->nsub;
        e = e->next;
    }
    j = env->once || (flags & REG_LEFT);
    DEBUG_TEST(0x0080,(sfprintf(sfstdout, "AHA#%04d parse once=%d\n", __LINE__, j)),(0));
    while ((i = parse(env, e, &env->done, (unsigned char*)s)) == NONE || advance && !env->best[0].rm_eo && !(advance = 0))
    {
        if (j)
            goto done;
        i = MBSIZE(s);
        s += i;
        if ((unsigned char*)s > env->end - env->min)
            goto done;
        if (env->stack)
            env->best[0].rm_so += i;
    }
    if ((flags & REG_LEFT) && env->stack && env->best[0].rm_so)
        goto done;
 hit:
    if (k = env->error)
        goto done;
    if (i == CUT)
    {
        k = env->error = REG_NOMATCH;
        goto done;
    }
    if (!(env->flags & REG_NOSUB))
    {
        k = (env->flags & (REG_SHELL|REG_AUGMENTED)) == (REG_SHELL|REG_AUGMENTED);
        for (i = j = m = 0; j < nmatch; i++)
            if (!i || !k || (i & 1))
            {
                if (i > n)
                    match[j] = state.nomatch;
                else
                    match[m = j] = env->best[i];
                j++;
            }
        if (k)
        {
            while (m > 0 && match[m].rm_so == -1 && match[m].rm_eo == -1)
                m--;
            ((regex_t*)p)->re_nsub = m;
        }
    }
    k = 0;
 done:
    stkold(stkstd, &env->stk);
    env->stk.base = 0;
    if (k > REG_NOMATCH)
        fatal(p->env->disc, k, NiL);
    return k;
}

void
regfree(regex_t* p)
{
    Env_t*  env;

    if (p && (env = p->env))
    {
#if _REG_subcomp
        if (env->sub)
        {
            regsubfree(p);
            p->re_sub = 0;
        }
#endif
        p->env = 0;
        if (--env->refs <= 0 && !(env->disc->re_flags & REG_NOFREE))
        {
            drop(env->disc, env->rex);
            if (env->pos)
                vecclose(env->pos);
            if (env->bestpos)
                vecclose(env->bestpos);
            if (env->stk.base)
                stkold(stkstd, &env->stk);
            alloc(env->disc, env, 0);
        }
    }
}