The R Project SVN R

/*-
 * Copyright (c) 1992, 1993, 1994 Henry Spencer.
 * Copyright (c) 1992, 1993, 1994
 *  The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Henry Spencer.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by the University of
 *  California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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.
 *
 *  @(#)regcomp.c   8.5 (Berkeley) 3/20/94
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)regcomp.c   8.5 (Berkeley) 3/20/94";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <stdlib.h>
#include <regex.h>

#include "collate.h"

#include "utils.h"
#include "regex2.h"

#include "cclass.h"
#include "cname.h"

/*
 * parse structure, passed up and down to avoid global variables and
 * other clumsinesses
 */
struct parse {
    char *next;     /* next character in RE */
    char *end;      /* end of string (-> NUL normally) */
    int error;      /* has an error been seen? */
    sop *strip;     /* malloced strip */
    sopno ssize;        /* malloced strip size (allocated) */
    sopno slen;     /* malloced strip length (used) */
    int ncsalloc;       /* number of csets allocated */
    struct re_guts *g;
#   define  NPAREN  10  /* we need to remember () 1-9 for back refs */
    sopno pbegin[NPAREN];   /* -> ( ([0] unused) */
    sopno pend[NPAREN]; /* -> ) ([0] unused) */
};

/* ========= begin header generated by ./mkh ========= */
#ifdef __cplusplus
extern "C" {
#endif

/* === regcomp.c === */
static void p_ere __P((struct parse *p, int stop));
static void p_ere_exp __P((struct parse *p));
static void p_str __P((struct parse *p));
static void p_bre __P((struct parse *p, int end1, int end2));
static int p_simp_re __P((struct parse *p, int starordinary));
static int p_count __P((struct parse *p));
static void p_bracket __P((struct parse *p));
static void p_b_term __P((struct parse *p, cset *cs));
static void p_b_cclass __P((struct parse *p, cset *cs));
static void p_b_eclass __P((struct parse *p, cset *cs));
static char p_b_symbol __P((struct parse *p));
static char p_b_coll_elem __P((struct parse *p, int endc));
static char othercase __P((int ch));
static void bothcases __P((struct parse *p, int ch));
static void ordinary __P((struct parse *p, int ch));
static void nonnewline __P((struct parse *p));
static void repeat __P((struct parse *p, sopno start, int from, int to));
static int seterr __P((struct parse *p, int e));
static cset *allocset __P((struct parse *p));
static void freeset __P((struct parse *p, cset *cs));
static int freezeset __P((struct parse *p, cset *cs));
static int firstch __P((struct parse *p, cset *cs));
static int nch __P((struct parse *p, cset *cs));
static void mcadd __P((struct parse *p, cset *cs, char *cp));
#if used
static void mcsub __P((cset *cs, char *cp));
static int mcin __P((cset *cs, char *cp));
static char *mcfind __P((cset *cs, char *cp));
#endif
static void mcinvert __P((struct parse *p, cset *cs));
static void mccase __P((struct parse *p, cset *cs));
static int isinsets __P((struct re_guts *g, int c));
static int samesets __P((struct re_guts *g, int c1, int c2));
static void categorize __P((struct parse *p, struct re_guts *g));
static sopno dupl __P((struct parse *p, sopno start, sopno finish));
static void doemit __P((struct parse *p, sop op, size_t opnd));
static void doinsert __P((struct parse *p, sop op, size_t opnd, sopno pos));
static void dofwd __P((struct parse *p, sopno pos, sop value));
static void enlarge __P((struct parse *p, sopno size));
static void stripsnug __P((struct parse *p, struct re_guts *g));
static void findmust __P((struct parse *p, struct re_guts *g));
static sopno pluscount __P((struct parse *p, struct re_guts *g));

#ifdef __cplusplus
}
#endif
/* ========= end header generated by ./mkh ========= */

static char nuls[10];       /* place to point scanner in event of error */

/*
 * macros for use with parse structure
 * BEWARE:  these know that the parse structure is named `p' !!!
 */
#define PEEK()  (*p->next)
#define PEEK2() (*(p->next+1))
#define MORE()  (p->next < p->end)
#define MORE2() (p->next+1 < p->end)
#define SEE(c)  (MORE() && PEEK() == (c))
#define SEETWO(a, b)    (MORE() && MORE2() && PEEK() == (a) && PEEK2() == (b))
#define EAT(c)  ((SEE(c)) ? (NEXT(), 1) : 0)
#define EATTWO(a, b)    ((SEETWO(a, b)) ? (NEXT2(), 1) : 0)
#define NEXT()  (p->next++)
#define NEXT2() (p->next += 2)
#define NEXTn(n)    (p->next += (n))
#define GETNEXT()   (*p->next++)
#define SETERROR(e) seterr(p, (e))
#define REQUIRE(co, e)  ((co) || SETERROR(e))
#define MUSTSEE(c, e)   (REQUIRE(MORE() && PEEK() == (c), e))
#define MUSTEAT(c, e)   (REQUIRE(MORE() && GETNEXT() == (c), e))
#define MUSTNOTSEE(c, e)    (REQUIRE(!MORE() || PEEK() != (c), e))
#define EMIT(op, sopnd) doemit(p, (sop)(op), (size_t)(sopnd))
#define INSERT(op, pos) doinsert(p, (sop)(op), HERE()-(pos)+1, pos)
#define AHEAD(pos)      dofwd(p, pos, HERE()-(pos))
#define ASTERN(sop, pos)    EMIT(sop, HERE()-pos)
#define HERE()      (p->slen)
#define THERE()     (p->slen - 1)
#define THERETHERE()    (p->slen - 2)
#define DROP(n) (p->slen -= (n))

#ifndef NDEBUG
static int never = 0;       /* for use in asserts; shuts lint up */
#else
#define never   0        /* some <assert.h>s have bugs too */
#endif

/*
 - regcomp - interface for parser and compilation
 = extern int regcomp(regex_t *, const char *, int);
 = #define  REG_BASIC   0000
 = #define  REG_EXTENDED    0001
 = #define  REG_ICASE   0002
 = #define  REG_NOSUB   0004
 = #define  REG_NEWLINE 0010
 = #define  REG_NOSPEC  0020
 = #define  REG_PEND    0040
 = #define  REG_DUMP    0200
 */
int             /* 0 success, otherwise REG_something */
regcomp(preg, pattern, cflags)
regex_t *preg;
const char *pattern;
int cflags;
{
    struct parse pa;
    register struct re_guts *g;
    register struct parse *p = &pa;
    register int i;
    register size_t len;
#ifdef REDEBUG
#   define  GOODFLAGS(f)    (f)
#else
#   define  GOODFLAGS(f)    ((f)&~REG_DUMP)
#endif

    cflags = GOODFLAGS(cflags);
    if ((cflags&REG_EXTENDED) && (cflags&REG_NOSPEC))
        return(REG_INVARG);

    if (cflags&REG_PEND) {
        if (preg->re_endp < pattern)
            return(REG_INVARG);
        len = preg->re_endp - pattern;
    } else
        len = strlen((char *)pattern);

    /* do the mallocs early so failure handling is easy */
    g = (struct re_guts *)malloc(sizeof(struct re_guts) +
                            (NC-1)*sizeof(cat_t));
    if (g == NULL)
        return(REG_ESPACE);
    p->ssize = len/(size_t)2*(size_t)3 + (size_t)1; /* ugh */
    p->strip = (sop *)malloc(p->ssize * sizeof(sop));
    p->slen = 0;
    if (p->strip == NULL) {
        free((char *)g);
        return(REG_ESPACE);
    }

    /* set things up */
    p->g = g;
    p->next = (char *)pattern;  /* convenience; we do not modify it */
    p->end = p->next + len;
    p->error = 0;
    p->ncsalloc = 0;
    for (i = 0; i < NPAREN; i++) {
        p->pbegin[i] = 0;
        p->pend[i] = 0;
    }
    g->csetsize = NC;
    g->sets = NULL;
    g->setbits = NULL;
    g->ncsets = 0;
    g->cflags = cflags;
    g->iflags = 0;
    g->nbol = 0;
    g->neol = 0;
    g->must = NULL;
    g->mlen = 0;
    g->nsub = 0;
    g->ncategories = 1; /* category 0 is "everything else" */
    g->categories = &g->catspace[-(CHAR_MIN)];
    (void) memset((char *)g->catspace, 0, NC*sizeof(cat_t));
    g->backrefs = 0;

    /* do it */
    EMIT(OEND, 0);
    g->firststate = THERE();
    if (cflags&REG_EXTENDED)
        p_ere(p, OUT);
    else if (cflags&REG_NOSPEC)
        p_str(p);
    else
        p_bre(p, OUT, OUT);
    EMIT(OEND, 0);
    g->laststate = THERE();

    /* tidy up loose ends and fill things in */
    categorize(p, g);
    stripsnug(p, g);
    findmust(p, g);
    g->nplus = pluscount(p, g);
    g->magic = MAGIC2;
    preg->re_nsub = g->nsub;
    preg->re_g = g;
    preg->re_magic = MAGIC1;
#ifndef REDEBUG
    /* not debugging, so can't rely on the assert() in regexec() */
    if (g->iflags&BAD)
        SETERROR(REG_ASSERT);
#endif

    /* win or lose, we're done */
    if (p->error != 0)  /* lose */
        regfree(preg);
    return(p->error);
}

/*
 - p_ere - ERE parser top level, concatenation and alternation
 == static void p_ere(register struct parse *p, int stop);
 */
static void
p_ere(p, stop)
register struct parse *p;
int stop;           /* character this ERE should end at */
{
    register char c;
    register sopno prevback;
    register sopno prevfwd;
    register sopno conc;
    register int first = 1;     /* is this the first alternative? */

    for (;;) {
        /* do a bunch of concatenated expressions */
        conc = HERE();
        while (MORE() && (c = PEEK()) != '|' && c != stop)
            p_ere_exp(p);
        (void)REQUIRE(HERE() != conc, REG_EMPTY);   /* require nonempty */

        if (!EAT('|'))
            break;      /* NOTE BREAK OUT */

        if (first) {
            INSERT(OCH_, conc); /* offset is wrong */
            prevfwd = conc;
            prevback = conc;
            first = 0;
        }
        ASTERN(OOR1, prevback);
        prevback = THERE();
        AHEAD(prevfwd);         /* fix previous offset */
        prevfwd = HERE();
        EMIT(OOR2, 0);          /* offset is very wrong */
    }

    if (!first) {       /* tail-end fixups */
        AHEAD(prevfwd);
        ASTERN(O_CH, prevback);
    }

    assert(!MORE() || SEE(stop));
}

/*
 - p_ere_exp - parse one subERE, an atom possibly followed by a repetition op
 == static void p_ere_exp(register struct parse *p);
 */
static void
p_ere_exp(p)
register struct parse *p;
{
    register char c;
    register sopno pos;
    register int count;
    register int count2;
    register sopno subno;
    int wascaret = 0;

    assert(MORE());     /* caller should have ensured this */
    c = GETNEXT();

    pos = HERE();
    switch (c) {
    case '(':
        (void)REQUIRE(MORE(), REG_EPAREN);
        p->g->nsub++;
        subno = p->g->nsub;
        if (subno < NPAREN)
            p->pbegin[subno] = HERE();
        EMIT(OLPAREN, subno);
        if (!SEE(')'))
            p_ere(p, ')');
        if (subno < NPAREN) {
            p->pend[subno] = HERE();
            assert(p->pend[subno] != 0);
        }
        EMIT(ORPAREN, subno);
        (void)MUSTEAT(')', REG_EPAREN);
        break;
#ifndef POSIX_MISTAKE
    case ')':       /* happens only if no current unmatched ( */
        /*
         * You may ask, why the ifndef?  Because I didn't notice
         * this until slightly too late for 1003.2, and none of the
         * other 1003.2 regular-expression reviewers noticed it at
         * all.  So an unmatched ) is legal POSIX, at least until
         * we can get it fixed.
         */
        SETERROR(REG_EPAREN);
        break;
#endif
    case '^':
        EMIT(OBOL, 0);
        p->g->iflags |= USEBOL;
        p->g->nbol++;
        wascaret = 1;
        break;
    case '$':
        EMIT(OEOL, 0);
        p->g->iflags |= USEEOL;
        p->g->neol++;
        break;
    case '|':
        SETERROR(REG_EMPTY);
        break;
    case '*':
    case '+':
    case '?':
        SETERROR(REG_BADRPT);
        break;
    case '.':
        if (p->g->cflags&REG_NEWLINE)
            nonnewline(p);
        else
            EMIT(OANY, 0);
        break;
    case '[':
        p_bracket(p);
        break;
    case '\\':
        (void)REQUIRE(MORE(), REG_EESCAPE);
        c = GETNEXT();
        ordinary(p, c);
        break;
    case '{':       /* okay as ordinary except if digit follows */
        (void)REQUIRE(!MORE() || !isdigit(PEEK()), REG_BADRPT);
        /* FALLTHROUGH */
    default:
        ordinary(p, c);
        break;
    }

    if (!MORE())
        return;
    c = PEEK();
    /* we call { a repetition if followed by a digit */
    if (!( c == '*' || c == '+' || c == '?' ||
                (c == '{' && MORE2() && isdigit(PEEK2())) ))
        return;     /* no repetition, we're done */
    NEXT();

    (void)REQUIRE(!wascaret, REG_BADRPT);
    switch (c) {
    case '*':   /* implemented as +? */
        /* this case does not require the (y|) trick, noKLUDGE */
        INSERT(OPLUS_, pos);
        ASTERN(O_PLUS, pos);
        INSERT(OQUEST_, pos);
        ASTERN(O_QUEST, pos);
        break;
    case '+':
        INSERT(OPLUS_, pos);
        ASTERN(O_PLUS, pos);
        break;
    case '?':
        /* KLUDGE: emit y? as (y|) until subtle bug gets fixed */
        INSERT(OCH_, pos);      /* offset slightly wrong */
        ASTERN(OOR1, pos);      /* this one's right */
        AHEAD(pos);         /* fix the OCH_ */
        EMIT(OOR2, 0);          /* offset very wrong... */
        AHEAD(THERE());         /* ...so fix it */
        ASTERN(O_CH, THERETHERE());
        break;
    case '{':
        count = p_count(p);
        if (EAT(',')) {
            if (isdigit(PEEK())) {
                count2 = p_count(p);
                (void)REQUIRE(count <= count2, REG_BADBR);
            } else      /* single number with comma */
                count2 = INFINITY;
        } else      /* just a single number */
            count2 = count;
        repeat(p, pos, count, count2);
        if (!EAT('}')) {    /* error heuristics */
            while (MORE() && PEEK() != '}')
                NEXT();
            (void)REQUIRE(MORE(), REG_EBRACE);
            SETERROR(REG_BADBR);
        }
        break;
    }

    if (!MORE())
        return;
    c = PEEK();
    if (!( c == '*' || c == '+' || c == '?' ||
                (c == '{' && MORE2() && isdigit(PEEK2())) ) )
        return;
    SETERROR(REG_BADRPT);
}

/*
 - p_str - string (no metacharacters) "parser"
 == static void p_str(register struct parse *p);
 */
static void
p_str(p)
register struct parse *p;
{
    (void)REQUIRE(MORE(), REG_EMPTY);
    while (MORE())
        ordinary(p, GETNEXT());
}

/*
 - p_bre - BRE parser top level, anchoring and concatenation
 == static void p_bre(register struct parse *p, register int end1, \
 == register int end2);
 * Giving end1 as OUT essentially eliminates the end1/end2 check.
 *
 * This implementation is a bit of a kludge, in that a trailing $ is first
 * taken as an ordinary character and then revised to be an anchor.  The
 * only undesirable side effect is that '$' gets included as a character
 * category in such cases.  This is fairly harmless; not worth fixing.
 * The amount of lookahead needed to avoid this kludge is excessive.
 */
static void
p_bre(p, end1, end2)
register struct parse *p;
register int end1;      /* first terminating character */
register int end2;      /* second terminating character */
{
    register sopno start = HERE();
    register int first = 1;         /* first subexpression? */
    register int wasdollar = 0;

    if (EAT('^')) {
        EMIT(OBOL, 0);
        p->g->iflags |= USEBOL;
        p->g->nbol++;
    }
    while (MORE() && !SEETWO(end1, end2)) {
        wasdollar = p_simp_re(p, first);
        first = 0;
    }
    if (wasdollar) {    /* oops, that was a trailing anchor */
        DROP(1);
        EMIT(OEOL, 0);
        p->g->iflags |= USEEOL;
        p->g->neol++;
    }

    (void)REQUIRE(HERE() != start, REG_EMPTY);  /* require nonempty */
}

/*
 - p_simp_re - parse a simple RE, an atom possibly followed by a repetition
 == static int p_simp_re(register struct parse *p, int starordinary);
 */
static int          /* was the simple RE an unbackslashed $? */
p_simp_re(p, starordinary)
register struct parse *p;
int starordinary;       /* is a leading * an ordinary character? */
{
    register int c;
    register int count;
    register int count2;
    register sopno pos;
    register int i;
    register sopno subno;
#   define  BACKSL  (1<<CHAR_BIT)

    pos = HERE();       /* repetion op, if any, covers from here */

    assert(MORE());     /* caller should have ensured this */
    c = GETNEXT();
    if (c == '\\') {
        (void)REQUIRE(MORE(), REG_EESCAPE);
        c = BACKSL | (unsigned char)GETNEXT();
    }
    switch (c) {
    case '.':
        if (p->g->cflags&REG_NEWLINE)
            nonnewline(p);
        else
            EMIT(OANY, 0);
        break;
    case '[':
        p_bracket(p);
        break;
    case BACKSL|'{':
        SETERROR(REG_BADRPT);
        break;
    case BACKSL|'(':
        p->g->nsub++;
        subno = p->g->nsub;
        if (subno < NPAREN)
            p->pbegin[subno] = HERE();
        EMIT(OLPAREN, subno);
        /* the MORE here is an error heuristic */
        if (MORE() && !SEETWO('\\', ')'))
            p_bre(p, '\\', ')');
        if (subno < NPAREN) {
            p->pend[subno] = HERE();
            assert(p->pend[subno] != 0);
        }
        EMIT(ORPAREN, subno);
        (void)REQUIRE(EATTWO('\\', ')'), REG_EPAREN);
        break;
    case BACKSL|')':    /* should not get here -- must be user */
    case BACKSL|'}':
        SETERROR(REG_EPAREN);
        break;
    case BACKSL|'1':
    case BACKSL|'2':
    case BACKSL|'3':
    case BACKSL|'4':
    case BACKSL|'5':
    case BACKSL|'6':
    case BACKSL|'7':
    case BACKSL|'8':
    case BACKSL|'9':
        i = (c&~BACKSL) - '0';
        assert(i < NPAREN);
        if (p->pend[i] != 0) {
            assert(i <= p->g->nsub);
            EMIT(OBACK_, i);
            assert(p->pbegin[i] != 0);
            assert(OP(p->strip[p->pbegin[i]]) == OLPAREN);
            assert(OP(p->strip[p->pend[i]]) == ORPAREN);
            (void) dupl(p, p->pbegin[i]+1, p->pend[i]);
            EMIT(O_BACK, i);
        } else
            SETERROR(REG_ESUBREG);
        p->g->backrefs = 1;
        break;
    case '*':
        (void)REQUIRE(starordinary, REG_BADRPT);
        /* FALLTHROUGH */
    default:
        ordinary(p, c &~ BACKSL);
        break;
    }

    if (EAT('*')) {     /* implemented as +? */
        /* this case does not require the (y|) trick, noKLUDGE */
        INSERT(OPLUS_, pos);
        ASTERN(O_PLUS, pos);
        INSERT(OQUEST_, pos);
        ASTERN(O_QUEST, pos);
    } else if (EATTWO('\\', '{')) {
        count = p_count(p);
        if (EAT(',')) {
            if (MORE() && isdigit(PEEK())) {
                count2 = p_count(p);
                (void)REQUIRE(count <= count2, REG_BADBR);
            } else      /* single number with comma */
                count2 = INFINITY;
        } else      /* just a single number */
            count2 = count;
        repeat(p, pos, count, count2);
        if (!EATTWO('\\', '}')) {   /* error heuristics */
            while (MORE() && !SEETWO('\\', '}'))
                NEXT();
            (void)REQUIRE(MORE(), REG_EBRACE);
            SETERROR(REG_BADBR);
        }
    } else if (c == (unsigned char)'$') /* $ (but not \$) ends it */
        return(1);

    return(0);
}

/*
 - p_count - parse a repetition count
 == static int p_count(register struct parse *p);
 */
static int          /* the value */
p_count(p)
register struct parse *p;
{
    register int count = 0;
    register int ndigits = 0;

    while (MORE() && isdigit(PEEK()) && count <= DUPMAX) {
        count = count*10 + (GETNEXT() - '0');
        ndigits++;
    }

    (void)REQUIRE(ndigits > 0 && count <= DUPMAX, REG_BADBR);
    return(count);
}

/*
 - p_bracket - parse a bracketed character list
 == static void p_bracket(register struct parse *p);
 *
 * Note a significant property of this code:  if the allocset() did SETERROR,
 * no set operations are done.
 */
static void
p_bracket(p)
register struct parse *p;
{
    register cset *cs = allocset(p);
    register int invert = 0;

    /* Dept of Truly Sickening Special-Case Kludges */
    if (p->next + 5 < p->end && strncmp(p->next, "[:<:]]", 6) == 0) {
        EMIT(OBOW, 0);
        NEXTn(6);
        return;
    }
    if (p->next + 5 < p->end && strncmp(p->next, "[:>:]]", 6) == 0) {
        EMIT(OEOW, 0);
        NEXTn(6);
        return;
    }

    if (EAT('^'))
        invert++;   /* make note to invert set at end */
    if (EAT(']'))
        CHadd(cs, ']');
    else if (EAT('-'))
        CHadd(cs, '-');
    while (MORE() && PEEK() != ']' && !SEETWO('-', ']'))
        p_b_term(p, cs);
    if (EAT('-'))
        CHadd(cs, '-');
    (void)MUSTEAT(']', REG_EBRACK);

    if (p->error != 0)  /* don't mess things up further */
        return;

    if (p->g->cflags&REG_ICASE) {
        register int i;
        register int ci;

        for (i = p->g->csetsize - 1; i >= 0; i--)
            if (CHIN(cs, i) && isalpha(i)) {
                ci = othercase(i);
                if (ci != i)
                    CHadd(cs, ci);
            }
        if (cs->multis != NULL)
            mccase(p, cs);
    }
    if (invert) {
        register int i;

        for (i = p->g->csetsize - 1; i >= 0; i--)
            if (CHIN(cs, i))
                CHsub(cs, i);
            else
                CHadd(cs, i);
        if (p->g->cflags&REG_NEWLINE)
            CHsub(cs, '\n');
        if (cs->multis != NULL)
            mcinvert(p, cs);
    }

    assert(cs->multis == NULL);     /* xxx */

    if (nch(p, cs) == 1) {      /* optimize singleton sets */
        ordinary(p, firstch(p, cs));
        freeset(p, cs);
    } else
        EMIT(OANYOF, freezeset(p, cs));
}

/*
 - p_b_term - parse one term of a bracketed character list
 == static void p_b_term(register struct parse *p, register cset *cs);
 */
static void
p_b_term(p, cs)
register struct parse *p;
register cset *cs;
{
    register char c;
    register char start, finish;
    register int i;

    /* classify what we've got */
    switch ((MORE()) ? PEEK() : '\0') {
    case '[':
        c = (MORE2()) ? PEEK2() : '\0';
        break;
    case '-':
        SETERROR(REG_ERANGE);
        return;         /* NOTE RETURN */
        break;
    default:
        c = '\0';
        break;
    }

    switch (c) {
    case ':':       /* character class */
        NEXT2();
        (void)REQUIRE(MORE(), REG_EBRACK);
        c = PEEK();
        (void)REQUIRE(c != '-' && c != ']', REG_ECTYPE);
        p_b_cclass(p, cs);
        (void)REQUIRE(MORE(), REG_EBRACK);
        (void)REQUIRE(EATTWO(':', ']'), REG_ECTYPE);
        break;
    case '=':       /* equivalence class */
        NEXT2();
        (void)REQUIRE(MORE(), REG_EBRACK);
        c = PEEK();
        (void)REQUIRE(c != '-' && c != ']', REG_ECOLLATE);
        p_b_eclass(p, cs);
        (void)REQUIRE(MORE(), REG_EBRACK);
        (void)REQUIRE(EATTWO('=', ']'), REG_ECOLLATE);
        break;
    default:        /* symbol, ordinary character, or range */
/* xxx revision needed for multichar stuff */
        start = p_b_symbol(p);
        if (SEE('-') && MORE2() && PEEK2() != ']') {
            /* range */
            NEXT();
            if (EAT('-'))
                finish = '-';
            else
                finish = p_b_symbol(p);
        } else
            finish = start;
        if (start == finish)
            CHadd(cs, start);
        else {
            if (__collate_load_error) {
                (void)REQUIRE((uch)start <= (uch)finish, REG_ERANGE);
                for (i = (uch)start; i <= (uch)finish; i++)
                    CHadd(cs, i);
            } else {
                (void)REQUIRE(__collate_range_cmp(start, finish) <= 0, REG_ERANGE);
                for (i = CHAR_MIN; i <= CHAR_MAX; i++) {
                    if (   __collate_range_cmp(start, i) <= 0
                        && __collate_range_cmp(i, finish) <= 0
                       )
                        CHadd(cs, i);
                }
            }
        }
        break;
    }
}

/*
 - p_b_cclass - parse a character-class name and deal with it
 == static void p_b_cclass(register struct parse *p, register cset *cs);
 */
static void
p_b_cclass(p, cs)
register struct parse *p;
register cset *cs;
{
    register int c;
    register char *sp = p->next;
    register struct cclass *cp;
    register size_t len;

    while (MORE() && isalpha((uch)PEEK()))
        NEXT();
    len = p->next - sp;
    for (cp = cclasses; cp->name != NULL; cp++)
        if (strncmp(cp->name, sp, len) == 0 && cp->name[len] == '\0')
            break;
    if (cp->name == NULL) {
        /* oops, didn't find it */
        SETERROR(REG_ECTYPE);
        return;
    }

    switch (cp->fidx) {
    case CALNUM:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isalnum((uch)c))
                CHadd(cs, c);
        break;
    case CALPHA:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isalpha((uch)c))
                CHadd(cs, c);
        break;
    case CBLANK:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isblank((uch)c))
                CHadd(cs, c);
        break;
    case CCNTRL:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (iscntrl((uch)c))
                CHadd(cs, c);
        break;
    case CDIGIT:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isdigit((uch)c))
                CHadd(cs, c);
        break;
    case CGRAPH:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isgraph((uch)c))
                CHadd(cs, c);
        break;
    case CLOWER:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (islower((uch)c))
                CHadd(cs, c);
        break;
    case CPRINT:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isprint((uch)c))
                CHadd(cs, c);
        break;
    case CPUNCT:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (ispunct((uch)c))
                CHadd(cs, c);
        break;
    case CSPACE:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isspace((uch)c))
                CHadd(cs, c);
        break;
    case CUPPER:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isupper((uch)c))
                CHadd(cs, c);
        break;
    case CXDIGIT:
        for (c = CHAR_MIN; c <= CHAR_MAX; c++)
            if (isxdigit((uch)c))
                CHadd(cs, c);
        break;
    }
#if 0
    for (u = cp->multis; *u != '\0'; u += strlen(u) + 1)
        MCadd(p, cs, u);
#endif
}

/*
 - p_b_eclass - parse an equivalence-class name and deal with it
 == static void p_b_eclass(register struct parse *p, register cset *cs);
 *
 * This implementation is incomplete. xxx
 */
static void
p_b_eclass(p, cs)
register struct parse *p;
register cset *cs;
{
    register char c;

    c = p_b_coll_elem(p, '=');
    CHadd(cs, c);
}

/*
 - p_b_symbol - parse a character or [..]ed multicharacter collating symbol
 == static char p_b_symbol(register struct parse *p);
 */
static char         /* value of symbol */
p_b_symbol(p)
register struct parse *p;
{
    register char value;

    (void)REQUIRE(MORE(), REG_EBRACK);
    if (!EATTWO('[', '.'))
        return(GETNEXT());

    /* collating symbol */
    value = p_b_coll_elem(p, '.');
    (void)REQUIRE(EATTWO('.', ']'), REG_ECOLLATE);
    return(value);
}

/*
 - p_b_coll_elem - parse a collating-element name and look it up
 == static char p_b_coll_elem(register struct parse *p, int endc);
 */
static char         /* value of collating element */
p_b_coll_elem(p, endc)
register struct parse *p;
int endc;           /* name ended by endc,']' */
{
    register char *sp = p->next;
    register struct cname *cp;
    register int len;

    while (MORE() && !SEETWO(endc, ']'))
        NEXT();
    if (!MORE()) {
        SETERROR(REG_EBRACK);
        return(0);
    }
    len = p->next - sp;
    for (cp = cnames; cp->name != NULL; cp++)
        if (strncmp(cp->name, sp, len) == 0 && cp->name[len] == '\0')
            return(cp->code);   /* known name */
    if (len == 1)
        return(*sp);    /* single character */
    SETERROR(REG_ECOLLATE);         /* neither */
    return(0);
}

/*
 - othercase - return the case counterpart of an alphabetic
 == static char othercase(int ch);
 */
static char         /* if no counterpart, return ch */
othercase(ch)
int ch;
{
    ch = (unsigned char)ch;
    assert(isalpha(ch));
    if (isupper(ch))
        return(tolower(ch));
    else if (islower(ch))
        return(toupper(ch));
    else            /* peculiar, but could happen */
        return(ch);
}

/*
 - bothcases - emit a dualcase version of a two-case character
 == static void bothcases(register struct parse *p, int ch);
 *
 * Boy, is this implementation ever a kludge...
 */
static void
bothcases(p, ch)
register struct parse *p;
int ch;
{
    register char *oldnext = p->next;
    register char *oldend = p->end;
    char bracket[3];

    ch = (unsigned char)ch;
    assert(othercase(ch) != ch);    /* p_bracket() would recurse */
    p->next = bracket;
    p->end = bracket+2;
    bracket[0] = ch;
    bracket[1] = ']';
    bracket[2] = '\0';
    p_bracket(p);
    assert(p->next == bracket+2);
    p->next = oldnext;
    p->end = oldend;
}

/*
 - ordinary - emit an ordinary character
 == static void ordinary(register struct parse *p, register int ch);
 */
static void
ordinary(p, ch)
register struct parse *p;
register int ch;
{
    register cat_t *cap = p->g->categories;

    if ((p->g->cflags&REG_ICASE) && isalpha((unsigned char)ch) && othercase(ch) != ch)
        bothcases(p, ch);
    else {
        EMIT(OCHAR, (unsigned char)ch);
        if (cap[ch] == 0)
            cap[ch] = p->g->ncategories++;
    }
}

/*
 - nonnewline - emit REG_NEWLINE version of OANY
 == static void nonnewline(register struct parse *p);
 *
 * Boy, is this implementation ever a kludge...
 */
static void
nonnewline(p)
register struct parse *p;
{
    register char *oldnext = p->next;
    register char *oldend = p->end;
    char bracket[4];

    p->next = bracket;
    p->end = bracket+3;
    bracket[0] = '^';
    bracket[1] = '\n';
    bracket[2] = ']';
    bracket[3] = '\0';
    p_bracket(p);
    assert(p->next == bracket+3);
    p->next = oldnext;
    p->end = oldend;
}

/*
 - repeat - generate code for a bounded repetition, recursively if needed
 == static void repeat(register struct parse *p, sopno start, int from, int to);
 */
static void
repeat(p, start, from, to)
register struct parse *p;
sopno start;            /* operand from here to end of strip */
int from;           /* repeated from this number */
int to;             /* to this number of times (maybe INFINITY) */
{
    register sopno finish = HERE();
#   define  N   2
#   define  INF 3
#   define  REP(f, t)   ((f)*8 + (t))
#   define  MAP(n)  (((n) <= 1) ? (n) : ((n) == INFINITY) ? INF : N)
    register sopno copy;

    if (p->error != 0)  /* head off possible runaway recursion */
        return;

    assert(from <= to);

    switch (REP(MAP(from), MAP(to))) {
    case REP(0, 0):         /* must be user doing this */
        DROP(finish-start); /* drop the operand */
        break;
    case REP(0, 1):         /* as x{1,1}? */
    case REP(0, N):         /* as x{1,n}? */
    case REP(0, INF):       /* as x{1,}? */
        /* KLUDGE: emit y? as (y|) until subtle bug gets fixed */
        INSERT(OCH_, start);        /* offset is wrong... */
        repeat(p, start+1, 1, to);
        ASTERN(OOR1, start);
        AHEAD(start);           /* ... fix it */
        EMIT(OOR2, 0);
        AHEAD(THERE());
        ASTERN(O_CH, THERETHERE());
        break;
    case REP(1, 1):         /* trivial case */
        /* done */
        break;
    case REP(1, N):         /* as x?x{1,n-1} */
        /* KLUDGE: emit y? as (y|) until subtle bug gets fixed */
        INSERT(OCH_, start);
        ASTERN(OOR1, start);
        AHEAD(start);
        EMIT(OOR2, 0);          /* offset very wrong... */
        AHEAD(THERE());         /* ...so fix it */
        ASTERN(O_CH, THERETHERE());
        copy = dupl(p, start+1, finish+1);
        assert(copy == finish+4);
        repeat(p, copy, 1, to-1);
        break;
    case REP(1, INF):       /* as x+ */
        INSERT(OPLUS_, start);
        ASTERN(O_PLUS, start);
        break;
    case REP(N, N):         /* as xx{m-1,n-1} */
        copy = dupl(p, start, finish);
        repeat(p, copy, from-1, to-1);
        break;
    case REP(N, INF):       /* as xx{n-1,INF} */
        copy = dupl(p, start, finish);
        repeat(p, copy, from-1, to);
        break;
    default:            /* "can't happen" */
        SETERROR(REG_ASSERT);   /* just in case */
        break;
    }
}

/*
 - seterr - set an error condition
 == static int seterr(register struct parse *p, int e);
 */
static int          /* useless but makes type checking happy */
seterr(p, e)
register struct parse *p;
int e;
{
    if (p->error == 0)  /* keep earliest error condition */
        p->error = e;
    p->next = nuls;     /* try to bring things to a halt */
    p->end = nuls;
    return(0);      /* make the return value well-defined */
}

/*
 - allocset - allocate a set of characters for []
 == static cset *allocset(register struct parse *p);
 */
static cset *
allocset(p)
register struct parse *p;
{
    register int no = p->g->ncsets++;
    register size_t nc;
    register size_t nbytes;
    register cset *cs;
    register size_t css = (size_t)p->g->csetsize;
    register int i;

    if (no >= p->ncsalloc) {    /* need another column of space */
        p->ncsalloc += CHAR_BIT;
        nc = p->ncsalloc;
        assert(nc % CHAR_BIT == 0);
        nbytes = nc / CHAR_BIT * css;
        if (p->g->sets == NULL)
            p->g->sets = (cset *)malloc(nc * sizeof(cset));
        else
            p->g->sets = (cset *)realloc((char *)p->g->sets,
                            nc * sizeof(cset));
        if (p->g->setbits == NULL)
            p->g->setbits = (uch *)malloc(nbytes);
        else {
            p->g->setbits = (uch *)realloc((char *)p->g->setbits,
                                nbytes);
            /* xxx this isn't right if setbits is now NULL */
            for (i = 0; i < no; i++)
                p->g->sets[i].ptr = p->g->setbits + css*(i/CHAR_BIT);
        }
        if (p->g->sets != NULL && p->g->setbits != NULL)
            (void) memset((char *)p->g->setbits + (nbytes - css),
                                0, css);
        else {
            no = 0;
            SETERROR(REG_ESPACE);
            /* caller's responsibility not to do set ops */
        }
    }

    assert(p->g->sets != NULL); /* xxx */
    cs = &p->g->sets[no];
    cs->ptr = p->g->setbits + css*((no)/CHAR_BIT);
    cs->mask = 1 << ((no) % CHAR_BIT);
    cs->hash = 0;
    cs->smultis = 0;
    cs->multis = NULL;

    return(cs);
}

/*
 - freeset - free a now-unused set
 == static void freeset(register struct parse *p, register cset *cs);
 */
static void
freeset(p, cs)
register struct parse *p;
register cset *cs;
{
    register int i;
    register cset *top = &p->g->sets[p->g->ncsets];
    register size_t css = (size_t)p->g->csetsize;

    for (i = 0; i < css; i++)
        CHsub(cs, i);
    if (cs == top-1)    /* recover only the easy case */
        p->g->ncsets--;
}

/*
 - freezeset - final processing on a set of characters
 == static int freezeset(register struct parse *p, register cset *cs);
 *
 * The main task here is merging identical sets.  This is usually a waste
 * of time (although the hash code minimizes the overhead), but can win
 * big if REG_ICASE is being used.  REG_ICASE, by the way, is why the hash
 * is done using addition rather than xor -- all ASCII [aA] sets xor to
 * the same value!
 */
static int          /* set number */
freezeset(p, cs)
register struct parse *p;
register cset *cs;
{
    register short h = cs->hash;
    register int i;
    register cset *top = &p->g->sets[p->g->ncsets];
    register cset *cs2;
    register size_t css = (size_t)p->g->csetsize;

    /* look for an earlier one which is the same */
    for (cs2 = &p->g->sets[0]; cs2 < top; cs2++)
        if (cs2->hash == h && cs2 != cs) {
            /* maybe */
            for (i = 0; i < css; i++)
                if (!!CHIN(cs2, i) != !!CHIN(cs, i))
                    break;      /* no */
            if (i == css)
                break;          /* yes */
        }

    if (cs2 < top) {    /* found one */
        freeset(p, cs);
        cs = cs2;
    }

    return((int)(cs - p->g->sets));
}

/*
 - firstch - return first character in a set (which must have at least one)
 == static int firstch(register struct parse *p, register cset *cs);
 */
static int          /* character; there is no "none" value */
firstch(p, cs)
register struct parse *p;
register cset *cs;
{
    register int i;
    register size_t css = (size_t)p->g->csetsize;

    for (i = 0; i < css; i++)
        if (CHIN(cs, i))
            return((unsigned char)i);
    assert(never);
    return(0);      /* arbitrary */
}

/*
 - nch - number of characters in a set
 == static int nch(register struct parse *p, register cset *cs);
 */
static int
nch(p, cs)
register struct parse *p;
register cset *cs;
{
    register int i;
    register size_t css = (size_t)p->g->csetsize;
    register int n = 0;

    for (i = 0; i < css; i++)
        if (CHIN(cs, i))
            n++;
    return(n);
}

/*
 - mcadd - add a collating element to a cset
 == static void mcadd(register struct parse *p, register cset *cs, \
 == register char *cp);
 */
static void
mcadd(p, cs, cp)
register struct parse *p;
register cset *cs;
register char *cp;
{
    register size_t oldend = cs->smultis;

    cs->smultis += strlen(cp) + 1;
    if (cs->multis == NULL)
        cs->multis = malloc(cs->smultis);
    else
        cs->multis = realloc(cs->multis, cs->smultis);
    if (cs->multis == NULL) {
        SETERROR(REG_ESPACE);
        return;
    }

    (void) strcpy(cs->multis + oldend - 1, cp);
    cs->multis[cs->smultis - 1] = '\0';
}

#if used
/*
 - mcsub - subtract a collating element from a cset
 == static void mcsub(register cset *cs, register char *cp);
 */
static void
mcsub(cs, cp)
register cset *cs;
register char *cp;
{
    register char *fp = mcfind(cs, cp);
    register size_t len = strlen(fp);

    assert(fp != NULL);
    (void) memmove(fp, fp + len + 1,
                cs->smultis - (fp + len + 1 - cs->multis));
    cs->smultis -= len;

    if (cs->smultis == 0) {
        free(cs->multis);
        cs->multis = NULL;
        return;
    }

    cs->multis = realloc(cs->multis, cs->smultis);
    assert(cs->multis != NULL);
}

/*
 - mcin - is a collating element in a cset?
 == static int mcin(register cset *cs, register char *cp);
 */
static int
mcin(cs, cp)
register cset *cs;
register char *cp;
{
    return(mcfind(cs, cp) != NULL);
}

/*
 - mcfind - find a collating element in a cset
 == static char *mcfind(register cset *cs, register char *cp);
 */
static char *
mcfind(cs, cp)
register cset *cs;
register char *cp;
{
    register char *p;

    if (cs->multis == NULL)
        return(NULL);
    for (p = cs->multis; *p != '\0'; p += strlen(p) + 1)
        if (strcmp(cp, p) == 0)
            return(p);
    return(NULL);
}
#endif

/*
 - mcinvert - invert the list of collating elements in a cset
 == static void mcinvert(register struct parse *p, register cset *cs);
 *
 * This would have to know the set of possibilities.  Implementation
 * is deferred.
 */
static void
mcinvert(p, cs)
register struct parse *p;
register cset *cs;
{
    assert(cs->multis == NULL); /* xxx */
}

/*
 - mccase - add case counterparts of the list of collating elements in a cset
 == static void mccase(register struct parse *p, register cset *cs);
 *
 * This would have to know the set of possibilities.  Implementation
 * is deferred.
 */
static void
mccase(p, cs)
register struct parse *p;
register cset *cs;
{
    assert(cs->multis == NULL); /* xxx */
}

/*
 - isinsets - is this character in any sets?
 == static int isinsets(register struct re_guts *g, int c);
 */
static int          /* predicate */
isinsets(g, c)
register struct re_guts *g;
int c;
{
    register uch *col;
    register int i;
    register int ncols = (g->ncsets+(CHAR_BIT-1)) / CHAR_BIT;
    register unsigned uc = (unsigned char)c;

    for (i = 0, col = g->setbits; i < ncols; i++, col += g->csetsize)
        if (col[uc] != 0)
            return(1);
    return(0);
}

/*
 - samesets - are these two characters in exactly the same sets?
 == static int samesets(register struct re_guts *g, int c1, int c2);
 */
static int          /* predicate */
samesets(g, c1, c2)
register struct re_guts *g;
int c1;
int c2;
{
    register uch *col;
    register int i;
    register int ncols = (g->ncsets+(CHAR_BIT-1)) / CHAR_BIT;
    register unsigned uc1 = (unsigned char)c1;
    register unsigned uc2 = (unsigned char)c2;

    for (i = 0, col = g->setbits; i < ncols; i++, col += g->csetsize)
        if (col[uc1] != col[uc2])
            return(0);
    return(1);
}

/*
 - categorize - sort out character categories
 == static void categorize(struct parse *p, register struct re_guts *g);
 */
static void
categorize(p, g)
struct parse *p;
register struct re_guts *g;
{
    register cat_t *cats = g->categories;
    register int c;
    register int c2;
    register cat_t cat;

    /* avoid making error situations worse */
    if (p->error != 0)
        return;

    for (c = CHAR_MIN; c <= CHAR_MAX; c++)
        if (cats[c] == 0 && isinsets(g, c)) {
            cat = g->ncategories++;
            cats[c] = cat;
            for (c2 = c+1; c2 <= CHAR_MAX; c2++)
                if (cats[c2] == 0 && samesets(g, c, c2))
                    cats[c2] = cat;
        }
}

/*
 - dupl - emit a duplicate of a bunch of sops
 == static sopno dupl(register struct parse *p, sopno start, sopno finish);
 */
static sopno            /* start of duplicate */
dupl(p, start, finish)
register struct parse *p;
sopno start;            /* from here */
sopno finish;           /* to this less one */
{
    register sopno ret = HERE();
    register sopno len = finish - start;

    assert(finish >= start);
    if (len == 0)
        return(ret);
    enlarge(p, p->ssize + len); /* this many unexpected additions */
    assert(p->ssize >= p->slen + len);
    (void) memcpy((char *)(p->strip + p->slen),
        (char *)(p->strip + start), (size_t)len*sizeof(sop));
    p->slen += len;
    return(ret);
}

/*
 - doemit - emit a strip operator
 == static void doemit(register struct parse *p, sop op, size_t opnd);
 *
 * It might seem better to implement this as a macro with a function as
 * hard-case backup, but it's just too big and messy unless there are
 * some changes to the data structures.  Maybe later.
 */
static void
doemit(p, op, opnd)
register struct parse *p;
sop op;
size_t opnd;
{
    /* avoid making error situations worse */
    if (p->error != 0)
        return;

    /* deal with oversize operands ("can't happen", more or less) */
    assert(opnd < 1<<OPSHIFT);

    /* deal with undersized strip */
    if (p->slen >= p->ssize)
        enlarge(p, (p->ssize+1) / 2 * 3);   /* +50% */
    assert(p->slen < p->ssize);

    /* finally, it's all reduced to the easy case */
    p->strip[p->slen++] = SOP(op, opnd);
}

/*
 - doinsert - insert a sop into the strip
 == static void doinsert(register struct parse *p, sop op, size_t opnd, sopno pos);
 */
static void
doinsert(p, op, opnd, pos)
register struct parse *p;
sop op;
size_t opnd;
sopno pos;
{
    register sopno sn;
    register sop s;
    register int i;

    /* avoid making error situations worse */
    if (p->error != 0)
        return;

    sn = HERE();
    EMIT(op, opnd);     /* do checks, ensure space */
    assert(HERE() == sn+1);
    s = p->strip[sn];

    /* adjust paren pointers */
    assert(pos > 0);
    for (i = 1; i < NPAREN; i++) {
        if (p->pbegin[i] >= pos) {
            p->pbegin[i]++;
        }
        if (p->pend[i] >= pos) {
            p->pend[i]++;
        }
    }

    memmove((char *)&p->strip[pos+1], (char *)&p->strip[pos],
                        (HERE()-pos-1)*sizeof(sop));
    p->strip[pos] = s;
}

/*
 - dofwd - complete a forward reference
 == static void dofwd(register struct parse *p, sopno pos, sop value);
 */
static void
dofwd(p, pos, value)
register struct parse *p;
register sopno pos;
sop value;
{
    /* avoid making error situations worse */
    if (p->error != 0)
        return;

    assert(value < 1<<OPSHIFT);
    p->strip[pos] = OP(p->strip[pos]) | value;
}

/*
 - enlarge - enlarge the strip
 == static void enlarge(register struct parse *p, sopno size);
 */
static void
enlarge(p, size)
register struct parse *p;
register sopno size;
{
    register sop *sp;

    if (p->ssize >= size)
        return;

    sp = (sop *)realloc(p->strip, size*sizeof(sop));
    if (sp == NULL) {
        SETERROR(REG_ESPACE);
        return;
    }
    p->strip = sp;
    p->ssize = size;
}

/*
 - stripsnug - compact the strip
 == static void stripsnug(register struct parse *p, register struct re_guts *g);
 */
static void
stripsnug(p, g)
register struct parse *p;
register struct re_guts *g;
{
    g->nstates = p->slen;
    g->strip = (sop *)realloc((char *)p->strip, p->slen * sizeof(sop));
    if (g->strip == NULL) {
        SETERROR(REG_ESPACE);
        g->strip = p->strip;
    }
}

/*
 - findmust - fill in must and mlen with longest mandatory literal string
 == static void findmust(register struct parse *p, register struct re_guts *g);
 *
 * This algorithm could do fancy things like analyzing the operands of |
 * for common subsequences.  Someday.  This code is simple and finds most
 * of the interesting cases.
 *
 * Note that must and mlen got initialized during setup.
 */
static void
findmust(p, g)
struct parse *p;
register struct re_guts *g;
{
    register sop *scan;
    sop *start;
    register sop *newstart;
    register sopno newlen;
    register sop s;
    register char *cp;
    register sopno i;

    /* avoid making error situations worse */
    if (p->error != 0)
        return;

    /* find the longest OCHAR sequence in strip */
    newlen = 0;
    scan = g->strip + 1;
    do {
        s = *scan++;
        switch (OP(s)) {
        case OCHAR:     /* sequence member */
            if (newlen == 0)        /* new sequence */
                newstart = scan - 1;
            newlen++;
            break;
        case OPLUS_:        /* things that don't break one */
        case OLPAREN:
        case ORPAREN:
            break;
        case OQUEST_:       /* things that must be skipped */
        case OCH_:
            scan--;
            do {
                scan += OPND(s);
                s = *scan;
                /* assert() interferes w debug printouts */
                if (OP(s) != O_QUEST && OP(s) != O_CH &&
                            OP(s) != OOR2) {
                    g->iflags |= BAD;
                    return;
                }
            } while (OP(s) != O_QUEST && OP(s) != O_CH);
            /* fallthrough */
        default:        /* things that break a sequence */
            if (newlen > g->mlen) {     /* ends one */
                start = newstart;
                g->mlen = newlen;
            }
            newlen = 0;
            break;
        }
    } while (OP(s) != OEND);

    if (g->mlen == 0)       /* there isn't one */
        return;

    /* turn it into a character string */
    g->must = malloc((size_t)g->mlen + 1);
    if (g->must == NULL) {      /* argh; just forget it */
        g->mlen = 0;
        return;
    }
    cp = g->must;
    scan = start;
    for (i = g->mlen; i > 0; i--) {
        while (OP(s = *scan++) != OCHAR)
            continue;
        assert(cp < g->must + g->mlen);
        *cp++ = (char)OPND(s);
    }
    assert(cp == g->must + g->mlen);
    *cp++ = '\0';       /* just on general principles */
}

/*
 - pluscount - count + nesting
 == static sopno pluscount(register struct parse *p, register struct re_guts *g);
 */
static sopno            /* nesting depth */
pluscount(p, g)
struct parse *p;
register struct re_guts *g;
{
    register sop *scan;
    register sop s;
    register sopno plusnest = 0;
    register sopno maxnest = 0;

    if (p->error != 0)
        return(0);  /* there may not be an OEND */

    scan = g->strip + 1;
    do {
        s = *scan++;
        switch (OP(s)) {
        case OPLUS_:
            plusnest++;
            break;
        case O_PLUS:
            if (plusnest > maxnest)
                maxnest = plusnest;
            plusnest--;
            break;
        }
    } while (OP(s) != OEND);
    if (plusnest != 0)
        g->iflags |= BAD;
    return(maxnest);
}