/*
 * re_*comp and friends - compile REs
 * This file #includes several others (see the bottom).
 *
 * Copyright (c) 1998, 1999 Henry Spencer.  All rights reserved.
 *
 * Development of this software was funded, in part, by Cray Research Inc.,
 * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics
 * Corporation, none of whom are responsible for the results.  The author
 * thanks all of them.
 *
 * Redistribution and use in source and binary forms -- with or without
 * modification -- are permitted for any purpose, provided that
 * redistributions in source form retain this entire copyright notice and
 * indicate the origin and nature of any modifications.
 *
 * I'd appreciate being given credit for this package in the documentation
 * of software which uses it, but that is not a requirement.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "regguts.h"

/*
 * forward declarations, up here so forward datatypes etc. are defined early
 */
/* =====^!^===== begin forwards =====^!^===== */
/* automatically gathered by fwd; do not hand-edit */
/* === regcomp.c === */
int compile _ANSI_ARGS_((regex_t *, CONST chr *, size_t, int));
static VOID moresubs _ANSI_ARGS_((struct vars *, int));
static int freev _ANSI_ARGS_((struct vars *, int));
static VOID makesearch _ANSI_ARGS_((struct vars *, struct nfa *));
static struct subre *parse _ANSI_ARGS_((struct vars *, int, int, struct state *, struct state *));
static struct subre *parsebranch _ANSI_ARGS_((struct vars *, int, int, struct state *, struct state *, int));
static VOID parseqatom _ANSI_ARGS_((struct vars *, int, int, struct state *, struct state *, struct subre *));
static VOID nonword _ANSI_ARGS_((struct vars *, int, struct state *, struct state *));
static VOID word _ANSI_ARGS_((struct vars *, int, struct state *, struct state *));
static int scannum _ANSI_ARGS_((struct vars *));
static VOID repeat _ANSI_ARGS_((struct vars *, struct state *, struct state *, int, int));
static VOID bracket _ANSI_ARGS_((struct vars *, struct state *, struct state *));
static VOID cbracket _ANSI_ARGS_((struct vars *, struct state *, struct state *));
static VOID brackpart _ANSI_ARGS_((struct vars *, struct state *, struct state *));
static chr *scanplain _ANSI_ARGS_((struct vars *));
static VOID leaders _ANSI_ARGS_((struct vars *, struct cvec *));
static VOID onechr _ANSI_ARGS_((struct vars *, pchr, struct state *, struct state *));
static VOID dovec _ANSI_ARGS_((struct vars *, struct cvec *, struct state *, struct state *));
static celt nextleader _ANSI_ARGS_((struct vars *, pchr, pchr));
static VOID wordchrs _ANSI_ARGS_((struct vars *));
static struct subre *subre _ANSI_ARGS_((struct vars *, int, int, struct state *, struct state *));
static VOID freesubre _ANSI_ARGS_((struct vars *, struct subre *));
static VOID freesrnode _ANSI_ARGS_((struct vars *, struct subre *));
static VOID optst _ANSI_ARGS_((struct vars *, struct subre *));
static int numst _ANSI_ARGS_((struct subre *, int));
static VOID markst _ANSI_ARGS_((struct subre *));
static VOID cleanst _ANSI_ARGS_((struct vars *));
static long nfatree _ANSI_ARGS_((struct vars *, struct subre *, FILE *));
static long nfanode _ANSI_ARGS_((struct vars *, struct subre *, FILE *));
static int newlacon _ANSI_ARGS_((struct vars *, struct state *, struct state *, int));
static VOID freelacons _ANSI_ARGS_((struct subre *, int));
static VOID rfree _ANSI_ARGS_((regex_t *));
#ifdef REG_DEBUG
static VOID dump _ANSI_ARGS_((regex_t *, FILE *));
static VOID dumpst _ANSI_ARGS_((struct subre *, FILE *, int));
static VOID stdump _ANSI_ARGS_((struct subre *, FILE *, int));
static char *stid _ANSI_ARGS_((struct subre *, char *, size_t));
#endif
/* === regc_lex.c === */
static VOID lexstart _ANSI_ARGS_((struct vars *));
static VOID prefixes _ANSI_ARGS_((struct vars *));
static VOID lexnest _ANSI_ARGS_((struct vars *, chr *, chr *));
static VOID lexword _ANSI_ARGS_((struct vars *));
static int next _ANSI_ARGS_((struct vars *));
static int lexescape _ANSI_ARGS_((struct vars *));
static chr lexdigits _ANSI_ARGS_((struct vars *, int, int, int));
static int brenext _ANSI_ARGS_((struct vars *, pchr));
static VOID skip _ANSI_ARGS_((struct vars *));
static chr newline _ANSI_ARGS_((NOPARMS));
#ifdef REG_DEBUG
static chr *ch _ANSI_ARGS_((NOPARMS));
#endif
static chr chrnamed _ANSI_ARGS_((struct vars *, chr *, chr *, pchr));
/* === regc_color.c === */
static VOID initcm _ANSI_ARGS_((struct vars *, struct colormap *));
static VOID freecm _ANSI_ARGS_((struct colormap *));
static VOID cmtreefree _ANSI_ARGS_((struct colormap *, union tree *, int));
static color setcolor _ANSI_ARGS_((struct colormap *, pchr, pcolor));
static color maxcolor _ANSI_ARGS_((struct colormap *));
static color newcolor _ANSI_ARGS_((struct colormap *));
static VOID freecolor _ANSI_ARGS_((struct colormap *, pcolor));
static color pseudocolor _ANSI_ARGS_((struct colormap *));
static color subcolor _ANSI_ARGS_((struct colormap *, pchr c));
static color newsub _ANSI_ARGS_((struct colormap *, pcolor));
static VOID subrange _ANSI_ARGS_((struct vars *, pchr, pchr, struct state *, struct state *));
static VOID subblock _ANSI_ARGS_((struct vars *, pchr, struct state *, struct state *));
static VOID okcolors _ANSI_ARGS_((struct nfa *, struct colormap *));
static VOID colorchain _ANSI_ARGS_((struct colormap *, struct arc *));
static VOID uncolorchain _ANSI_ARGS_((struct colormap *, struct arc *));
static int singleton _ANSI_ARGS_((struct colormap *, pchr c));
static VOID rainbow _ANSI_ARGS_((struct nfa *, struct colormap *, int, pcolor, struct state *, struct state *));
static VOID colorcomplement _ANSI_ARGS_((struct nfa *, struct colormap *, int, struct state *, struct state *, struct state *));
#ifdef REG_DEBUG
static VOID dumpcolors _ANSI_ARGS_((struct colormap *, FILE *));
static VOID fillcheck _ANSI_ARGS_((struct colormap *, union tree *, int, FILE *));
static VOID dumpchr _ANSI_ARGS_((pchr, FILE *));
#endif
/* === regc_nfa.c === */
static struct nfa *newnfa _ANSI_ARGS_((struct vars *, struct colormap *, struct nfa *));
static VOID freenfa _ANSI_ARGS_((struct nfa *));
static struct state *newstate _ANSI_ARGS_((struct nfa *));
static struct state *newfstate _ANSI_ARGS_((struct nfa *, int flag));
static VOID dropstate _ANSI_ARGS_((struct nfa *, struct state *));
static VOID freestate _ANSI_ARGS_((struct nfa *, struct state *));
static VOID destroystate _ANSI_ARGS_((struct nfa *, struct state *));
static VOID newarc _ANSI_ARGS_((struct nfa *, int, pcolor, struct state *, struct state *));
static struct arc *allocarc _ANSI_ARGS_((struct nfa *, struct state *));
static VOID freearc _ANSI_ARGS_((struct nfa *, struct arc *));
static struct arc *findarc _ANSI_ARGS_((struct state *, int, pcolor));
static VOID cparc _ANSI_ARGS_((struct nfa *, struct arc *, struct state *, struct state *));
static VOID moveins _ANSI_ARGS_((struct nfa *, struct state *, struct state *));
static VOID copyins _ANSI_ARGS_((struct nfa *, struct state *, struct state *));
static VOID moveouts _ANSI_ARGS_((struct nfa *, struct state *, struct state *));
static VOID copyouts _ANSI_ARGS_((struct nfa *, struct state *, struct state *));
static VOID cloneouts _ANSI_ARGS_((struct nfa *, struct state *, struct state *, struct state *, int));
static VOID delsub _ANSI_ARGS_((struct nfa *, struct state *, struct state *));
static VOID deltraverse _ANSI_ARGS_((struct nfa *, struct state *, struct state *));
static VOID dupnfa _ANSI_ARGS_((struct nfa *, struct state *, struct state *, struct state *, struct state *));
static VOID duptraverse _ANSI_ARGS_((struct nfa *, struct state *, struct state *));
static VOID cleartraverse _ANSI_ARGS_((struct nfa *, struct state *));
static VOID specialcolors _ANSI_ARGS_((struct nfa *));
static long optimize _ANSI_ARGS_((struct nfa *, FILE *));
static VOID pullback _ANSI_ARGS_((struct nfa *, FILE *));
static int pull _ANSI_ARGS_((struct nfa *, struct arc *));
static VOID pushfwd _ANSI_ARGS_((struct nfa *, FILE *));
static int push _ANSI_ARGS_((struct nfa *, struct arc *));
#define	INCOMPATIBLE	1	/* destroys arc */
#define	SATISFIED	2	/* constraint satisfied */
#define	COMPATIBLE	3	/* compatible but not satisfied yet */
static int combine _ANSI_ARGS_((struct arc *, struct arc *));
static VOID fixempties _ANSI_ARGS_((struct nfa *, FILE *));
static int unempty _ANSI_ARGS_((struct nfa *, struct arc *));
static VOID cleanup _ANSI_ARGS_((struct nfa *));
static VOID markreachable _ANSI_ARGS_((struct nfa *, struct state *, struct state *, struct state *));
static VOID markcanreach _ANSI_ARGS_((struct nfa *, struct state *, struct state *, struct state *));
static long analyze _ANSI_ARGS_((struct nfa *));
static VOID compact _ANSI_ARGS_((struct nfa *, struct cnfa *));
static VOID carcsort _ANSI_ARGS_((struct carc *, struct carc *));
static VOID freecnfa _ANSI_ARGS_((struct cnfa *));
static VOID dumpnfa _ANSI_ARGS_((struct nfa *, FILE *));
#ifdef REG_DEBUG
static VOID dumpstate _ANSI_ARGS_((struct state *, FILE *));
static VOID dumparcs _ANSI_ARGS_((struct state *, FILE *));
static int dumprarcs _ANSI_ARGS_((struct arc *, struct state *, FILE *, int));
static VOID dumparc _ANSI_ARGS_((struct arc *, struct state *, FILE *));
static VOID dumpcnfa _ANSI_ARGS_((struct cnfa *, FILE *));
static VOID dumpcstate _ANSI_ARGS_((int, struct carc *, struct cnfa *, FILE *));
#endif
/* === regc_cvec.c === */
static struct cvec *newcvec _ANSI_ARGS_((int, int, int));
static struct cvec *clearcvec _ANSI_ARGS_((struct cvec *));
static VOID addchr _ANSI_ARGS_((struct cvec *, pchr));
static VOID addrange _ANSI_ARGS_((struct cvec *, pchr, pchr));
static VOID addmcce _ANSI_ARGS_((struct cvec *, chr *, chr *));
static int haschr _ANSI_ARGS_((struct cvec *, pchr));
static struct cvec *getcvec _ANSI_ARGS_((struct vars *, int, int, int));
static VOID freecvec _ANSI_ARGS_((struct cvec *));
/* === regc_locale.c === */
static int nmcces _ANSI_ARGS_((struct vars *));
static int nleaders _ANSI_ARGS_((struct vars *));
static struct cvec *allmcces _ANSI_ARGS_((struct vars *, struct cvec *));
static celt element _ANSI_ARGS_((struct vars *, chr *, chr *));
static struct cvec *range _ANSI_ARGS_((struct vars *, celt, celt, int));
static int before _ANSI_ARGS_((celt, celt));
static struct cvec *eclass _ANSI_ARGS_((struct vars *, celt, int));
static struct cvec *cclass _ANSI_ARGS_((struct vars *, chr *, chr *, int));
static struct cvec *allcases _ANSI_ARGS_((struct vars *, pchr));
/* automatically gathered by fwd; do not hand-edit */
/* =====^!^===== end forwards =====^!^===== */



/* internal variables, bundled for easy passing around */
struct vars {
	regex_t *re;
	chr *now;		/* scan pointer into string */
	chr *stop;		/* end of string */
	chr *savenow;		/* saved now and stop for "subroutine call" */
	chr *savestop;
	int err;		/* error code (0 if none) */
	int cflags;		/* copy of compile flags */
	int lasttype;		/* type of previous token */
	int nexttype;		/* type of next token */
	chr nextvalue;		/* value (if any) of next token */
	int lexcon;		/* lexical context type (see lex.c) */
	int nsubexp;		/* subexpression count */
	struct subre **subs;	/* subRE pointer vector */
	size_t nsubs;		/* length of vector */
	struct subre *sub10[10];	/* initial vector, enough for most */
	struct nfa *nfa;	/* the NFA */
	struct colormap *cm;	/* character color map */
	color nlcolor;		/* color of newline */
	struct state *wordchrs;	/* state in nfa holding word-char outarcs */
	struct subre *tree;	/* subexpression tree */
	struct subre *treechain;	/* all tree nodes allocated */
	struct subre *treefree;		/* any free tree nodes */
	int ntree;		/* number of tree nodes */
	struct cvec *cv;	/* interface cvec */
	struct cvec *cv2;	/* utility cvec */
	struct cvec *mcces;	/* collating-element information */
#		define	ISCELEADER(v,c)	(v->mcces != NULL && haschr(v->mcces, (c)))
	struct state *mccepbegin;	/* in nfa, start of MCCE prototypes */
	struct state *mccepend;	/* in nfa, end of MCCE prototypes */
	struct subre *lacons;	/* lookahead-constraint vector */
	int nlacons;		/* size of lacons */
};

/* parsing macros; most know that `v' is the struct vars pointer */
#define	NEXT()	(next(v))		/* advance by one token */
#define	SEE(t)	(v->nexttype == (t))	/* is next token this? */
#define	EAT(t)	(SEE(t) && next(v))	/* if next is this, swallow it */
#define	VISERR(vv)	((vv)->err != 0)	/* have we seen an error yet? */
#define	ISERR()	VISERR(v)
#define	VERR(vv,e)	((vv)->nexttype = EOS, ((vv)->err) ? (vv)->err :\
							((vv)->err = (e)))
#define	ERR(e)	VERR(v, e)		/* record an error */
#define	NOERR()	{if (ISERR()) return;}	/* if error seen, return */
#define	NOERRN()	{if (ISERR()) return NULL;}	/* NOERR with retval */
#define	NOERRZ()	{if (ISERR()) return 0;}	/* NOERR with retval */
#define	INSIST(c, e)	((c) ? 0 : ERR(e))	/* if condition false, error */
#define	NOTE(b)	(v->re->re_info |= (b))		/* note visible condition */
#define	EMPTYARC(x, y)	newarc(v->nfa, EMPTY, 0, x, y)

/* token type codes, some also used as NFA arc types */
#define	EMPTY	'n'		/* no token present */
#define	EOS	'e'		/* end of string */
#define	PLAIN	'p'		/* ordinary character */
#define	DIGIT	'd'		/* digit (in bound) */
#define	BACKREF	'b'		/* back reference */
#define	COLLEL	'I'		/* start of [. */
#define	ECLASS	'E'		/* start of [= */
#define	CCLASS	'C'		/* start of [: */
#define	END	'X'		/* end of [. [= [: */
#define	RANGE	'R'		/* - within [] which might be range delim. */
#define	LACON	'L'		/* lookahead constraint subRE */
#define	AHEAD	'a'		/* color-lookahead arc */
#define	BEHIND	'r'		/* color-lookbehind arc */
#define	WBDRY	'w'		/* word boundary constraint */
#define	NWBDRY	'W'		/* non-word-boundary constraint */
#define	SBEGIN	'A'		/* beginning of string (even if not BOL) */
#define	SEND	'Z'		/* end of string (even if not EOL) */
#define	PREFER	'P'		/* length preference */

/* is an arc colored, and hence on a color chain? */
#define	COLORED(a)	((a)->type == PLAIN || (a)->type == AHEAD || \
							(a)->type == BEHIND)



/* static function list */
static struct fns functions = {
	rfree,			/* regfree insides */
};



/*
 - compile - compile regular expression
 ^ int compile(regex_t *, CONST chr *, size_t, int);
 */
int
compile(regex_t *re, CONST chr *string,	size_t len, int flags)
{
	struct vars var;
	struct vars *v = &var;
	struct guts *g;
	int i;
	size_t j;
#ifdef REG_DEBUG
	FILE *debug = (flags&REG_PROGRESS) ? stdout : (FILE *)NULL;
#else
#	define debug NULL
#endif
#	define	CNOERR()	{ if (ISERR()) return freev(v, v->err); }

	/* sanity checks */

	if (re == NULL || string == NULL)
		return REG_INVARG;
	if ((flags&REG_QUOTE) &&
			(flags&(REG_ADVANCED|REG_EXPANDED|REG_NEWLINE)))
		return REG_INVARG;
	if (!(flags&REG_EXTENDED) && (flags&REG_ADVF))
		return REG_INVARG;

	/* initial setup (after which freev() is callable) */
	v->re = re;
	v->now = (chr *)string;
	v->stop = v->now + len;
	v->savenow = v->savestop = NULL;
	v->err = 0;
	v->cflags = flags;
	v->nsubexp = 0;
	v->subs = v->sub10;
	v->nsubs = 10;
	for (j = 0; j < v->nsubs; j++)
		v->subs[j] = NULL;
	v->nfa = NULL;
	v->cm = NULL;
	v->nlcolor = COLORLESS;
	v->wordchrs = NULL;
	v->tree = NULL;
	v->treechain = NULL;
	v->treefree = NULL;
	v->cv = NULL;
	v->cv2 = NULL;
	v->mcces = NULL;
	v->lacons = NULL;
	v->nlacons = 0;
	re->re_magic = REMAGIC;
	re->re_info = 0;		/* bits get set during parse */
	re->re_csize = sizeof(chr);
	re->re_guts = NULL;
	re->re_fns = VS(&functions);

	/* more complex setup, malloced things */
	re->re_guts = VS(MALLOC(sizeof(struct guts)));
	if (re->re_guts == NULL)
		return freev(v, REG_ESPACE);
	g = (struct guts *)re->re_guts;
	g->tree = NULL;
	initcm(v, &g->cmap);
	v->cm = &g->cmap;
	g->lacons = NULL;
	g->nlacons = 0;
	ZAPCNFA(g->search);
	v->nfa = newnfa(v, v->cm, (struct nfa *)NULL);
	CNOERR();
	v->cv = newcvec(100, 20, 10);
	if (v->cv == NULL)
		return freev(v, REG_ESPACE);
	i = nmcces(v);
	if (i > 0) {
		v->mcces = newcvec(nleaders(v), 0, i);
		CNOERR();
		v->mcces = allmcces(v, v->mcces);
		leaders(v, v->mcces);
		addmcce(v->mcces, (chr *)NULL, (chr *)NULL);	/* dummy */
	}
	CNOERR();

	/* parsing */
	lexstart(v);			/* also handles prefixes */
	if ((v->cflags&REG_NLSTOP) || (v->cflags&REG_NLANCH)) {
		/* assign newline a unique color */
		v->nlcolor = subcolor(v->cm, newline());
		okcolors(v->nfa, v->cm);
	}
	CNOERR();
	v->tree = parse(v, EOS, PLAIN, v->nfa->init, v->nfa->final);
	assert(SEE(EOS));		/* even if error; ISERR() => SEE(EOS) */
	CNOERR();
	assert(v->tree != NULL);

	/* finish setup of nfa and its subre tree */
	specialcolors(v->nfa);
	CNOERR();
#ifdef REG_DEBUG
	if (debug != NULL) {
		fprintf(debug, "\n\n\n========= RAW ==========\n");
		dumpnfa(v->nfa, debug);
		dumpst(v->tree, debug, 1);
	}
#endif
	optst(v, v->tree);
	v->ntree = numst(v->tree, 1);
	markst(v->tree);
	cleanst(v);
#ifdef REG_DEBUG
	if (debug != NULL) {
		fprintf(debug, "\n\n\n========= TREE FIXED ==========\n");
		dumpst(v->tree, debug, 1);
	}
#endif

	/* build compacted NFAs for tree and lacons */
	re->re_info |= nfatree(v, v->tree, debug);
	CNOERR();
	assert(v->nlacons == 0 || v->lacons != NULL);
	for (i = 1; i < v->nlacons; i++) {
#ifdef REG_DEBUG
		if (debug != NULL)
			fprintf(debug, "\n\n\n========= LA%d ==========\n", i);
#endif
		nfanode(v, &v->lacons[i], debug);
	}
	CNOERR();
	if (v->tree->flags&SHORTER)
		NOTE(REG_USHORTEST);

	/* build compacted NFAs for tree, lacons, fast search */
#ifdef REG_DEBUG
	if (debug != NULL)
		fprintf(debug, "\n\n\n========= SEARCH ==========\n");
#endif
	/* can sacrifice main NFA now, so use it as work area */
	(DISCARD)optimize(v->nfa, debug);
	CNOERR();
	makesearch(v, v->nfa);
	CNOERR();
	compact(v->nfa, &g->search);
	CNOERR();

	/* looks okay, package it up */
	re->re_nsub = v->nsubexp;
	v->re = NULL;			/* freev no longer frees re */
	g->magic = GUTSMAGIC;
	g->cflags = v->cflags;
	g->info = re->re_info;
	g->nsub = re->re_nsub;
	g->tree = v->tree;
	v->tree = NULL;
	g->ntree = v->ntree;
	g->icase = (v->cflags&REG_ICASE);
	g->lacons = v->lacons;
	v->lacons = NULL;
	g->nlacons = v->nlacons;

#ifdef REG_DEBUG
	if (flags&REG_DUMP)
		dump(re, stdout);
#endif

	assert(v->err == 0);
	return freev(v, 0);
}

/*
 - moresubs - enlarge subRE vector
 ^ static VOID moresubs(struct vars *, int);
 */
static VOID
moresubs(struct vars *v, int wanted)
{
	struct subre **p;
	size_t n;

	assert(wanted > 0 && (size_t)wanted >= v->nsubs);
	n = (size_t)wanted * 3 / 2 + 1;
	if (v->subs == v->sub10) {
		p = (struct subre **)MALLOC(n * sizeof(struct subre *));
		if (p != NULL)
			memcpy(VS(p), VS(v->subs),
					v->nsubs * sizeof(struct subre *));
	} else
		p = (struct subre **)REALLOC(v->subs, n*sizeof(struct subre *));
	if (p == NULL) {
		ERR(REG_ESPACE);
		return;
	}
	v->subs = p;
	for (p = &v->subs[v->nsubs]; v->nsubs < n; p++, v->nsubs++)
		*p = NULL;
	assert(v->nsubs == n);
	assert((size_t)wanted < v->nsubs);
}

/*
 - freev - free vars struct's substructures where necessary
 * Optionally does error-number setting, and always returns error code
 * (if any), to make error-handling code terser.
 ^ static int freev(struct vars *, int);
 */
static int
freev(struct vars *v, int err)
{
	if (v->re != NULL)
		rfree(v->re);
	if (v->subs != v->sub10)
		FREE(v->subs);
	if (v->nfa != NULL)
		freenfa(v->nfa);
	if (v->tree != NULL)
		freesubre(v, v->tree);
	if (v->treechain != NULL)
		cleanst(v);
	if (v->cv != NULL)
		freecvec(v->cv);
	if (v->cv2 != NULL)
		freecvec(v->cv2);
	if (v->mcces != NULL)
		freecvec(v->mcces);
	if (v->lacons != NULL)
		freelacons(v->lacons, v->nlacons);
	ERR(err);			/* nop if err==0 */

	return v->err;
}

/*
 - makesearch - turn an NFA into a search NFA (implicit prepend of .*?)
 * NFA must have been optimize()d already.
 ^ static VOID makesearch(struct vars *, struct nfa *);
 */
static VOID
makesearch(struct vars *v, struct nfa *nfa)
{
	struct arc *a;
	struct arc *b;
	struct state *pre = nfa->pre;
	struct state *s;
	struct state *s2;
	struct state *slist;

	/* no loops are needed if it's anchored */
	for (a = pre->outs; a != NULL; a = a->outchain) {
		assert(a->type == PLAIN);
		if (a->co != nfa->bos[0] && a->co != nfa->bos[1])
			break;
	}
	if (a != NULL) {
		/* add implicit .* in front */
		rainbow(nfa, v->cm, PLAIN, COLORLESS, pre, pre);

		/* and ^* and \A* too -- not always necessary, but harmless */
		newarc(nfa, PLAIN, nfa->bos[0], pre, pre);
		newarc(nfa, PLAIN, nfa->bos[1], pre, pre);
	}

	/*
	 * Now here's the subtle part.  Because many REs have no lookback
	 * constraints, often knowing when you were in the pre state tells
	 * you little; it's the next state(s) that are informative.  But
	 * some of them may have other inarcs, i.e. it may be possible to
	 * make actual progress and then return to one of them.  We must
	 * de-optimize such cases, splitting each such state into progress
	 * and no-progress states.
	 */

	/* first, make a list of the states */
	slist = NULL;
	for (a = pre->outs; a != NULL; a = a->outchain) {
		s = a->to;
		for (b = s->ins; b != NULL; b = b->inchain)
			if (b->from != pre)
				break;
		if (b != NULL) {		/* must be split */
			if (s->tmp == NULL) {  /* if not already in the list */
			                       /* (fixes bugs 505048, 230589, */
			                       /* 840258, 504785) */
				s->tmp = slist;
				slist = s;
			}
		}
	}

	/* do the splits */
	for (s = slist; s != NULL; s = s2) {
		s2 = newstate(nfa);
		copyouts(nfa, s, s2);
		for (a = s->ins; a != NULL; a = b) {
			b = a->inchain;
			if (a->from != pre) {
				cparc(nfa, a, a->from, s2);
				freearc(nfa, a);
			}
		}
		s2 = s->tmp;
		s->tmp = NULL;		/* clean up while we're at it */
	}
}

/*
 - parse - parse an RE
 * This is actually just the top level, which parses a bunch of branches
 * tied together with '|'.  They appear in the tree as the left children
 * of a chain of '|' subres.
 ^ static struct subre *parse(struct vars *, int, int, struct state *,
 ^	struct state *);
 */
static struct subre *
parse(struct vars *v, int stopper, int type, struct state *init, struct state *final)
{
	struct state *left;	/* scaffolding for branch */
	struct state *right;
	struct subre *branches;	/* top level */
	struct subre *branch;	/* current branch */
	struct subre *t;	/* temporary */
	int firstbranch;	/* is this the first branch? */

	assert(stopper == ')' || stopper == EOS);

	branches = subre(v, '|', LONGER, init, final);
	NOERRN();
	branch = branches;
	firstbranch = 1;
	do {	/* a branch */
		if (!firstbranch) {
			/* need a place to hang it */
			branch->right = subre(v, '|', LONGER, init, final);
			NOERRN();
			branch = branch->right;
		}
		firstbranch = 0;
		left = newstate(v->nfa);
		right = newstate(v->nfa);
		NOERRN();
		EMPTYARC(init, left);
		EMPTYARC(right, final);
		NOERRN();
		branch->left = parsebranch(v, stopper, type, left, right, 0);
		NOERRN();
		branch->flags |= UP(branch->flags | branch->left->flags);
		if ((branch->flags &~ branches->flags) != 0)	/* new flags */
			for (t = branches; t != branch; t = t->right)
				t->flags |= branch->flags;
	} while (EAT('|'));
	assert(SEE(stopper) || SEE(EOS));

	if (!SEE(stopper)) {
		assert(stopper == ')' && SEE(EOS));
		ERR(REG_EPAREN);
	}

	/* optimize out simple cases */
	if (branch == branches) {	/* only one branch */
		assert(branch->right == NULL);
		t = branch->left;
		branch->left = NULL;
		freesubre(v, branches);
		branches = t;
	} else if (!MESSY(branches->flags)) {	/* no interesting innards */
		freesubre(v, branches->left);
		branches->left = NULL;
		freesubre(v, branches->right);
		branches->right = NULL;
		branches->op = '=';
	}

	return branches;
}

/*
 - parsebranch - parse one branch of an RE
 * This mostly manages concatenation, working closely with parseqatom().
 * Concatenated things are bundled up as much as possible, with separate
 * ',' nodes introduced only when necessary due to substructure.
 ^ static struct subre *parsebranch(struct vars *, int, int, struct state *,
 ^	struct state *, int);
 */
static struct subre *
parsebranch(struct vars *v, int stopper, int type,
	    struct state *left, struct state *right, int partial)
{
	struct state *lp;	/* left end of current construct */
	int seencontent;	/* is there anything in this branch yet? */
	struct subre *t;

	lp = left;
	seencontent = 0;
	t = subre(v, '=', 0, left, right);	/* op '=' is tentative */
	NOERRN();

				/* Insert a \A (SBEGIN) in each toplevel branch */
	if ( stopper == EOS && !partial && (v->cflags&REG_BOSONLY)) {
		newarc(v->nfa, '^', 0, lp, right);
		newarc(v->nfa, '^', 1, lp, right);
		seencontent = 1;
	}

	while (!SEE('|') && !SEE(stopper) && !SEE(EOS)) {
		if (seencontent) {	/* implicit concat operator */
			lp = newstate(v->nfa);
			NOERRN();
			moveins(v->nfa, right, lp);
		}
		seencontent = 1;

		/* NB, recursion in parseqatom() may swallow rest of branch */
		parseqatom(v, stopper, type, lp, right, t);
	}

	if (!seencontent) {		/* empty branch */
		if (!partial)
			NOTE(REG_UUNSPEC);
		assert(lp == left);
		EMPTYARC(left, right);
	}

	return t;
}

/*
 - parseqatom - parse one quantified atom or constraint of an RE
 * The bookkeeping near the end cooperates very closely with parsebranch();
 * in particular, it contains a recursion that can involve parsing the rest
 * of the branch, making this function's name somewhat inaccurate.
 ^ static VOID parseqatom(struct vars *, int, int, struct state *,
 ^	struct state *, struct subre *);
 */
static VOID
parseqatom(struct vars *v, int stopper, int type,
	   struct state *lp, struct state *rp, struct subre *top)
{
	struct state *s;	/* temporaries for new states */
	struct state *s2;
#	define	ARCV(t, val)	newarc(v->nfa, t, val, lp, rp)
	int m, n;
	struct subre *atom;	/* atom's subtree */
	struct subre *t;
	int cap;		/* capturing parens? */
	int pos;		/* positive lookahead? */
	int subno;		/* capturing-parens or backref number */
	int atomtype;
	int qprefer;		/* quantifier short/long preference */
	int f;
	struct subre **atomp;	/* where the pointer to atom is */

	/* initial bookkeeping */
	atom = NULL;
	assert(lp->nouts == 0);	/* must string new code */
	assert(rp->nins == 0);	/*  between lp and rp */
	subno = 0;		/* just to shut lint up */

	/* an atom or constraint... */
	atomtype = v->nexttype;
	switch (atomtype) {
	/* first, constraints, which end by returning */
	case '^':
		ARCV('^', 1);
		if (v->cflags&REG_NLANCH)
			ARCV(BEHIND, v->nlcolor);
		NEXT();
		return;
		break;
	case '$':
		ARCV('$', 1);
		if (v->cflags&REG_NLANCH)
			ARCV(AHEAD, v->nlcolor);
		NEXT();
		return;
		break;
	case SBEGIN:
		ARCV('^', 1);	/* BOL */
		ARCV('^', 0);	/* or BOS */
		NEXT();
		return;
		break;
	case SEND:
		ARCV('$', 1);	/* EOL */
		ARCV('$', 0);	/* or EOS */
		NEXT();
		return;
		break;
	case '<':
		wordchrs(v);	/* does NEXT() */
		s = newstate(v->nfa);
		NOERR();
		nonword(v, BEHIND, lp, s);
		word(v, AHEAD, s, rp);
		return;
		break;
	case '>':
		wordchrs(v);	/* does NEXT() */
		s = newstate(v->nfa);
		NOERR();
		word(v, BEHIND, lp, s);
		nonword(v, AHEAD, s, rp);
		return;
		break;
	case WBDRY:
		wordchrs(v);	/* does NEXT() */
		s = newstate(v->nfa);
		NOERR();
		nonword(v, BEHIND, lp, s);
		word(v, AHEAD, s, rp);
		s = newstate(v->nfa);
		NOERR();
		word(v, BEHIND, lp, s);
		nonword(v, AHEAD, s, rp);
		return;
		break;
	case NWBDRY:
		wordchrs(v);	/* does NEXT() */
		s = newstate(v->nfa);
		NOERR();
		word(v, BEHIND, lp, s);
		word(v, AHEAD, s, rp);
		s = newstate(v->nfa);
		NOERR();
		nonword(v, BEHIND, lp, s);
		nonword(v, AHEAD, s, rp);
		return;
		break;
	case LACON:	/* lookahead constraint */
		pos = v->nextvalue;
		NEXT();
		s = newstate(v->nfa);
		s2 = newstate(v->nfa);
		NOERR();
		t = parse(v, ')', LACON, s, s2);
		freesubre(v, t);	/* internal structure irrelevant */
		assert(SEE(')') || ISERR());
		NEXT();
		n = newlacon(v, s, s2, pos);
		NOERR();
		ARCV(LACON, n);
		return;
		break;
	/* then errors, to get them out of the way */
	case '*':
	case '+':
	case '?':
	case '{':
		ERR(REG_BADRPT);
		return;
		break;
	default:
		ERR(REG_ASSERT);
		return;
		break;
	/* then plain characters, and minor variants on that theme */
	case ')':		/* unbalanced paren */
		if ((v->cflags&REG_ADVANCED) != REG_EXTENDED) {
			ERR(REG_EPAREN);
			return;
		}
		/* legal in EREs due to specification botch */
		NOTE(REG_UPBOTCH);
		/* fallthrough into case PLAIN */
	case PLAIN:
		onechr(v, v->nextvalue, lp, rp);
		okcolors(v->nfa, v->cm);
		NOERR();
		NEXT();
		break;
	case '[':
		if (v->nextvalue == 1)
			bracket(v, lp, rp);
		else
			cbracket(v, lp, rp);
		assert(SEE(']') || ISERR());
		NEXT();
		break;
	case '.':
		rainbow(v->nfa, v->cm, PLAIN,
				(v->cflags&REG_NLSTOP) ? v->nlcolor : COLORLESS,
				lp, rp);
		NEXT();
		break;
	/* and finally the ugly stuff */
	case '(':	/* value flags as capturing or non */
		cap = (type == LACON) ? 0 : v->nextvalue;
		if (cap) {
			v->nsubexp++;
			subno = v->nsubexp;
			if ((size_t)subno >= v->nsubs)
				moresubs(v, subno);
			assert((size_t)subno < v->nsubs);
		} else
			atomtype = PLAIN;	/* something that's not '(' */
		NEXT();
		/* need new endpoints because tree will contain pointers */
		s = newstate(v->nfa);
		s2 = newstate(v->nfa);
		NOERR();
		EMPTYARC(lp, s);
		EMPTYARC(s2, rp);
		NOERR();
		atom = parse(v, ')', PLAIN, s, s2);
		assert(SEE(')') || ISERR());
		NEXT();
		NOERR();
		if (cap) {
			v->subs[subno] = atom;
			t = subre(v, '(', atom->flags|CAP, lp, rp);
			NOERR();
			t->subno = subno;
			t->left = atom;
			atom = t;
		}
		/* postpone everything else pending possible {0} */
		break;
	case BACKREF:	/* the Feature From The Black Lagoon */
		INSIST(type != LACON, REG_ESUBREG);
		INSIST(v->nextvalue < v->nsubs, REG_ESUBREG);
		INSIST(v->subs[v->nextvalue] != NULL, REG_ESUBREG);
		NOERR();
		assert(v->nextvalue > 0);
		atom = subre(v, 'b', BACKR, lp, rp);
		subno = v->nextvalue;
		atom->subno = subno;
		EMPTYARC(lp, rp);	/* temporarily, so there's something */
		NEXT();
		break;
	}

	/* ...and an atom may be followed by a quantifier */
	switch (v->nexttype) {
	case '*':
		m = 0;
		n = INFINITY;
		qprefer = (v->nextvalue) ? LONGER : SHORTER;
		NEXT();
		break;
	case '+':
		m = 1;
		n = INFINITY;
		qprefer = (v->nextvalue) ? LONGER : SHORTER;
		NEXT();
		break;
	case '?':
		m = 0;
		n = 1;
		qprefer = (v->nextvalue) ? LONGER : SHORTER;
		NEXT();
		break;
	case '{':
		NEXT();
		m = scannum(v);
		if (EAT(',')) {
			if (SEE(DIGIT))
				n = scannum(v);
			else
				n = INFINITY;
			if (m > n) {
				ERR(REG_BADBR);
				return;
			}
			/* {m,n} exercises preference, even if it's {m,m} */
			qprefer = (v->nextvalue) ? LONGER : SHORTER;
		} else {
			n = m;
			/* {m} passes operand's preference through */
			qprefer = 0;
		}
		if (!SEE('}')) {	/* catches errors too */
			ERR(REG_BADBR);
			return;
		}
		NEXT();
		break;
	default:		/* no quantifier */
		m = n = 1;
		qprefer = 0;
		break;
	}

	/* annoying special case:  {0} or {0,0} cancels everything */
	if (m == 0 && n == 0) {
		if (atom != NULL)
			freesubre(v, atom);
		if (atomtype == '(')
			v->subs[subno] = NULL;
		delsub(v->nfa, lp, rp);
		EMPTYARC(lp, rp);
		return;
	}

	/* if not a messy case, avoid hard part */
	assert(!MESSY(top->flags));
	f = top->flags | qprefer | ((atom != NULL) ? atom->flags : 0);
	if (atomtype != '(' && atomtype != BACKREF && !MESSY(UP(f))) {
		if (!(m == 1 && n == 1))
			repeat(v, lp, rp, m, n);
		if (atom != NULL)
			freesubre(v, atom);
		top->flags = f;
		return;
	}

	/*
	 * hard part:  something messy
	 * That is, capturing parens, back reference, short/long clash, or
	 * an atom with substructure containing one of those.
	 */

	/* now we'll need a subre for the contents even if they're boring */
	if (atom == NULL) {
		atom = subre(v, '=', 0, lp, rp);
		NOERR();
	}

	/*
	 * prepare a general-purpose state skeleton
	 *
	 *    ---> [s] ---prefix---> [begin] ---atom---> [end] ----rest---> [rp]
	 *   /                                            /
	 * [lp] ----> [s2] ----bypass---------------------
	 *
	 * where bypass is an empty, and prefix is some repetitions of atom
	 */
	s = newstate(v->nfa);		/* first, new endpoints for the atom */
	s2 = newstate(v->nfa);
	NOERR();
	moveouts(v->nfa, lp, s);
	moveins(v->nfa, rp, s2);
	NOERR();
	atom->begin = s;
	atom->end = s2;
	s = newstate(v->nfa);		/* and spots for prefix and bypass */
	s2 = newstate(v->nfa);
	NOERR();
	EMPTYARC(lp, s);
	EMPTYARC(lp, s2);
	NOERR();

	/* break remaining subRE into x{...} and what follows */
	t = subre(v, '.', COMBINE(qprefer, atom->flags), lp, rp);
	t->left = atom;
	atomp = &t->left;
	/* here we should recurse... but we must postpone that to the end */

	/* split top into prefix and remaining */
	assert(top->op == '=' && top->left == NULL && top->right == NULL);
	top->left = subre(v, '=', top->flags, top->begin, lp);
	top->op = '.';
	top->right = t;

	/* if it's a backref, now is the time to replicate the subNFA */
	if (atomtype == BACKREF) {
		assert(atom->begin->nouts == 1);	/* just the EMPTY */
		delsub(v->nfa, atom->begin, atom->end);
		assert(v->subs[subno] != NULL);
		/* and here's why the recursion got postponed:  it must */
		/* wait until the skeleton is filled in, because it may */
		/* hit a backref that wants to copy the filled-in skeleton */
		dupnfa(v->nfa, v->subs[subno]->begin, v->subs[subno]->end,
						atom->begin, atom->end);
		NOERR();
	}

	/* it's quantifier time; first, turn x{0,...} into x{1,...}|empty */
	if (m == 0) {
		EMPTYARC(s2, atom->end);		/* the bypass */
		assert(PREF(qprefer) != 0);
		f = COMBINE(qprefer, atom->flags);
		t = subre(v, '|', f, lp, atom->end);
		NOERR();
		t->left = atom;
		t->right = subre(v, '|', PREF(f), s2, atom->end);
		NOERR();
		t->right->left = subre(v, '=', 0, s2, atom->end);
		NOERR();
		*atomp = t;
		atomp = &t->left;
		m = 1;
	}

	/* deal with the rest of the quantifier */
	if (atomtype == BACKREF) {
		/* special case:  backrefs have internal quantifiers */
		EMPTYARC(s, atom->begin);	/* empty prefix */
		/* just stuff everything into atom */
		repeat(v, atom->begin, atom->end, m, n);
		atom->min = (short)m;
		atom->max = (short)n;
		atom->flags |= COMBINE(qprefer, atom->flags);
	} else if (m == 1 && n == 1) {
		/* no/vacuous quantifier:  done */
		EMPTYARC(s, atom->begin);	/* empty prefix */
	} else {
		/* turn x{m,n} into x{m-1,n-1}x, with capturing */
		/*  parens in only second x */
		dupnfa(v->nfa, atom->begin, atom->end, s, atom->begin);
		assert(m >= 1 && m != INFINITY && n >= 1);
		repeat(v, s, atom->begin, m-1, (n == INFINITY) ? n : n-1);
		f = COMBINE(qprefer, atom->flags);
		t = subre(v, '.', f, s, atom->end);	/* prefix and atom */
		NOERR();
		t->left = subre(v, '=', PREF(f), s, atom->begin);
		NOERR();
		t->right = atom;
		*atomp = t;
	}

	/* and finally, look after that postponed recursion */
	t = top->right;
	if (!(SEE('|') || SEE(stopper) || SEE(EOS)))
		t->right = parsebranch(v, stopper, type, atom->end, rp, 1);
	else {
		EMPTYARC(atom->end, rp);
		t->right = subre(v, '=', 0, atom->end, rp);
	}
	assert(SEE('|') || SEE(stopper) || SEE(EOS));
	t->flags |= COMBINE(t->flags, t->right->flags);
	top->flags |= COMBINE(top->flags, t->flags);
}

/*
 - nonword - generate arcs for non-word-character ahead or behind
 ^ static VOID nonword(struct vars *, int, struct state *, struct state *);
 */
static VOID
nonword(struct vars *v, int dir, struct state *lp, struct state *rp)
{
	int anchor = (dir == AHEAD) ? '$' : '^';

	assert(dir == AHEAD || dir == BEHIND);
	newarc(v->nfa, anchor, 1, lp, rp);
	newarc(v->nfa, anchor, 0, lp, rp);
	colorcomplement(v->nfa, v->cm, dir, v->wordchrs, lp, rp);
	/* (no need for special attention to \n) */
}

/*
 - word - generate arcs for word character ahead or behind
 ^ static VOID word(struct vars *, int, struct state *, struct state *);
 */
static VOID
word(struct vars *v, int dir, struct state *lp, struct state *rp)
{
	assert(dir == AHEAD || dir == BEHIND);
	cloneouts(v->nfa, v->wordchrs, lp, rp, dir);
	/* (no need for special attention to \n) */
}

/*
 - scannum - scan a number
 ^ static int scannum(struct vars *);
 */
static int			/* value, <= DUPMAX */
scannum(struct vars *v)
{
	int n = 0;

	while (SEE(DIGIT) && n < DUPMAX) {
		n = n*10 + v->nextvalue;
		NEXT();
	}
	if (SEE(DIGIT) || n > DUPMAX) {
		ERR(REG_BADBR);
		return 0;
	}
	return n;
}

/*
 - repeat - replicate subNFA for quantifiers
 * The duplication sequences used here are chosen carefully so that any
 * pointers starting out pointing into the subexpression end up pointing into
 * the last occurrence.  (Note that it may not be strung between the same
 * left and right end states, however!)  This used to be important for the
 * subRE tree, although the important bits are now handled by the in-line
 * code in parse(), and when this is called, it doesn't matter any more.
 ^ static VOID repeat(struct vars *, struct state *, struct state *, int, int);
 */
static VOID
repeat(struct vars *v, struct state *lp, struct state *rp, int m, int n)
{
#	define	SOME	2
#	define	INF	3
#	define	PAIR(x, y)	((x)*4 + (y))
#	define	REDUCE(x)	( ((x) == INFINITY) ? INF : (((x) > 1) ? SOME : (x)) )
	CONST int rm = REDUCE(m);
	CONST int rn = REDUCE(n);
	struct state *s;
	struct state *s2;

	switch (PAIR(rm, rn)) {
	case PAIR(0, 0):		/* empty string */
		delsub(v->nfa, lp, rp);
		EMPTYARC(lp, rp);
		break;
	case PAIR(0, 1):		/* do as x| */
		EMPTYARC(lp, rp);
		break;
	case PAIR(0, SOME):		/* do as x{1,n}| */
		repeat(v, lp, rp, 1, n);
		NOERR();
		EMPTYARC(lp, rp);
		break;
	case PAIR(0, INF):		/* loop x around */
		s = newstate(v->nfa);
		NOERR();
		moveouts(v->nfa, lp, s);
		moveins(v->nfa, rp, s);
		EMPTYARC(lp, s);
		EMPTYARC(s, rp);
		break;
	case PAIR(1, 1):		/* no action required */
		break;
	case PAIR(1, SOME):		/* do as x{0,n-1}x = (x{1,n-1}|)x */
		s = newstate(v->nfa);
		NOERR();
		moveouts(v->nfa, lp, s);
		dupnfa(v->nfa, s, rp, lp, s);
		NOERR();
		repeat(v, lp, s, 1, n-1);
		NOERR();
		EMPTYARC(lp, s);
		break;
	case PAIR(1, INF):		/* add loopback arc */
		s = newstate(v->nfa);
		s2 = newstate(v->nfa);
		NOERR();
		moveouts(v->nfa, lp, s);
		moveins(v->nfa, rp, s2);
		EMPTYARC(lp, s);
		EMPTYARC(s2, rp);
		EMPTYARC(s2, s);
		break;
	case PAIR(SOME, SOME):		/* do as x{m-1,n-1}x */
		s = newstate(v->nfa);
		NOERR();
		moveouts(v->nfa, lp, s);
		dupnfa(v->nfa, s, rp, lp, s);
		NOERR();
		repeat(v, lp, s, m-1, n-1);
		break;
	case PAIR(SOME, INF):		/* do as x{m-1,}x */
		s = newstate(v->nfa);
		NOERR();
		moveouts(v->nfa, lp, s);
		dupnfa(v->nfa, s, rp, lp, s);
		NOERR();
		repeat(v, lp, s, m-1, n);
		break;
	default:
		ERR(REG_ASSERT);
		break;
	}
}

/*
 - bracket - handle non-complemented bracket expression
 * Also called from cbracket for complemented bracket expressions.
 ^ static VOID bracket(struct vars *, struct state *, struct state *);
 */
static VOID
bracket(struct vars *v, struct state *lp, struct state *rp)
{
	assert(SEE('['));
	NEXT();
	while (!SEE(']') && !SEE(EOS))
		brackpart(v, lp, rp);
	assert(SEE(']') || ISERR());
	okcolors(v->nfa, v->cm);
}

/*
 - cbracket - handle complemented bracket expression
 * We do it by calling bracket() with dummy endpoints, and then complementing
 * the result.  The alternative would be to invoke rainbow(), and then delete
 * arcs as the b.e. is seen... but that gets messy.
 ^ static VOID cbracket(struct vars *, struct state *, struct state *);
 */
static VOID
cbracket(struct vars *v, struct state *lp, struct state *rp)
{
	struct state *left = newstate(v->nfa);
	struct state *right = newstate(v->nfa);
	struct state *s;
	struct arc *a;			/* arc from lp */
	struct arc *ba;			/* arc from left, from bracket() */
	struct arc *pa;			/* MCCE-prototype arc */
	color co;
	chr *p;
	int i;

	NOERR();
	bracket(v, left, right);
	if (v->cflags&REG_NLSTOP)
		newarc(v->nfa, PLAIN, v->nlcolor, left, right);
	NOERR();

	assert(lp->nouts == 0);		/* all outarcs will be ours */

	/* easy part of complementing */
	colorcomplement(v->nfa, v->cm, PLAIN, left, lp, rp);
	NOERR();
	if (v->mcces == NULL) {		/* no MCCEs -- we're done */
		dropstate(v->nfa, left);
		assert(right->nins == 0);
		freestate(v->nfa, right);
		return;
	}

	/* but complementing gets messy in the presence of MCCEs... */
	NOTE(REG_ULOCALE);
	for (p = v->mcces->chrs, i = v->mcces->nchrs; i > 0; p++, i--) {
		co = GETCOLOR(v->cm, *p);
		a = findarc(lp, PLAIN, co);
		ba = findarc(left, PLAIN, co);
		if (ba == NULL) {
			assert(a != NULL);
			freearc(v->nfa, a);
		} else {
			assert(a == NULL);
		}
		s = newstate(v->nfa);
		NOERR();
		newarc(v->nfa, PLAIN, co, lp, s);
		NOERR();
		pa = findarc(v->mccepbegin, PLAIN, co);
		assert(pa != NULL);
		if (ba == NULL) {	/* easy case, need all of them */
			cloneouts(v->nfa, pa->to, s, rp, PLAIN);
			newarc(v->nfa, '$', 1, s, rp);
			newarc(v->nfa, '$', 0, s, rp);
			colorcomplement(v->nfa, v->cm, AHEAD, pa->to, s, rp);
		} else {		/* must be selective */
			if (findarc(ba->to, '$', 1) == NULL) {
				newarc(v->nfa, '$', 1, s, rp);
				newarc(v->nfa, '$', 0, s, rp);
				colorcomplement(v->nfa, v->cm, AHEAD, pa->to,
									 s, rp);
			}
			for (pa = pa->to->outs; pa != NULL; pa = pa->outchain)
				if (findarc(ba->to, PLAIN, pa->co) == NULL)
					newarc(v->nfa, PLAIN, pa->co, s, rp);
			if (s->nouts == 0)	/* limit of selectivity: none */
				dropstate(v->nfa, s);	/* frees arc too */
		}
		NOERR();
	}

	delsub(v->nfa, left, right);
	assert(left->nouts == 0);
	freestate(v->nfa, left);
	assert(right->nins == 0);
	freestate(v->nfa, right);
}

/*
 - brackpart - handle one item (or range) within a bracket expression
 ^ static VOID brackpart(struct vars *, struct state *, struct state *);
 */
static VOID
brackpart(struct vars *v, struct state *lp, struct state *rp)
{
	celt startc;
	celt endc;
	struct cvec *cv;
	chr *startp;
	chr *endp;
	chr c[1];

	/* parse something, get rid of special cases, take shortcuts */
	switch (v->nexttype) {
	case RANGE:			/* a-b-c or other botch */
		ERR(REG_ERANGE);
		return;
		break;
	case PLAIN:
		c[0] = v->nextvalue;
		NEXT();
		/* shortcut for ordinary chr (not range, not MCCE leader) */
		if (!SEE(RANGE) && !ISCELEADER(v, c[0])) {
			onechr(v, c[0], lp, rp);
			return;
		}
		startc = element(v, c, c+1);
		NOERR();
		break;
	case COLLEL:
		startp = v->now;
		endp = scanplain(v);
		INSIST(startp < endp, REG_ECOLLATE);
		NOERR();
		startc = element(v, startp, endp);
		NOERR();
		break;
	case ECLASS:
		startp = v->now;
		endp = scanplain(v);
		INSIST(startp < endp, REG_ECOLLATE);
		NOERR();
		startc = element(v, startp, endp);
		NOERR();
		cv = eclass(v, startc, (v->cflags&REG_ICASE));
		NOERR();
		dovec(v, cv, lp, rp);
		return;
		break;
	case CCLASS:
		startp = v->now;
		endp = scanplain(v);
		INSIST(startp < endp, REG_ECTYPE);
		NOERR();
		cv = cclass(v, startp, endp, (v->cflags&REG_ICASE));
		NOERR();
		dovec(v, cv, lp, rp);
		return;
		break;
	default:
		ERR(REG_ASSERT);
		return;
		break;
	}

	if (SEE(RANGE)) {
		NEXT();
		switch (v->nexttype) {
		case PLAIN:
		case RANGE:
			c[0] = v->nextvalue;
			NEXT();
			endc = element(v, c, c+1);
			NOERR();
			break;
		case COLLEL:
			startp = v->now;
			endp = scanplain(v);
			INSIST(startp < endp, REG_ECOLLATE);
			NOERR();
			endc = element(v, startp, endp);
			NOERR();
			break;
		default:
			ERR(REG_ERANGE);
			return;
			break;
		}
	} else
		endc = startc;

	/*
	 * Ranges are unportable.  Actually, standard C does
	 * guarantee that digits are contiguous, but making
	 * that an exception is just too complicated.
	 */
	if (startc != endc)
		NOTE(REG_UUNPORT);
	cv = range(v, startc, endc, (v->cflags&REG_ICASE));
	NOERR();
	dovec(v, cv, lp, rp);
}

/*
 - scanplain - scan PLAIN contents of [. etc.
 * Certain bits of trickery in lex.c know that this code does not try
 * to look past the final bracket of the [. etc.
 ^ static chr *scanplain(struct vars *);
 */
static chr *			/* just after end of sequence */
scanplain(struct vars *v)
{
	chr *endp;

	assert(SEE(COLLEL) || SEE(ECLASS) || SEE(CCLASS));
	NEXT();

	endp = v->now;
	while (SEE(PLAIN)) {
		endp = v->now;
		NEXT();
	}

	assert(SEE(END) || ISERR());
	NEXT();

	return endp;
}

/*
 - leaders - process a cvec of collating elements to also include leaders
 * Also gives all characters involved their own colors, which is almost
 * certainly necessary, and sets up little disconnected subNFA.
 ^ static VOID leaders(struct vars *, struct cvec *);
 */
static VOID
leaders(struct vars *v, struct cvec *cv)
{
	int mcce;
	chr *p;
	chr leader;
	struct state *s;
	struct arc *a;

	v->mccepbegin = newstate(v->nfa);
	v->mccepend = newstate(v->nfa);
	NOERR();

	for (mcce = 0; mcce < cv->nmcces; mcce++) {
		p = cv->mcces[mcce];
		leader = *p;
		if (!haschr(cv, leader)) {
			addchr(cv, leader);
			s = newstate(v->nfa);
			newarc(v->nfa, PLAIN, subcolor(v->cm, leader),
							v->mccepbegin, s);
			okcolors(v->nfa, v->cm);
		} else {
			a = findarc(v->mccepbegin, PLAIN,
						GETCOLOR(v->cm, leader));
			assert(a != NULL);
			s = a->to;
			assert(s != v->mccepend);
		}
		p++;
		assert(*p != 0 && *(p+1) == 0);	/* only 2-char MCCEs for now */
		newarc(v->nfa, PLAIN, subcolor(v->cm, *p), s, v->mccepend);
		okcolors(v->nfa, v->cm);
	}
}

/*
 - onechr - fill in arcs for a plain character, and possible case complements
 * This is mostly a shortcut for efficient handling of the common case.
 ^ static VOID onechr(struct vars *, pchr, struct state *, struct state *);
 */
static VOID
onechr(struct vars *v, pchr c, struct state *lp, struct state *rp)
{
	if (!(v->cflags&REG_ICASE)) {
		newarc(v->nfa, PLAIN, subcolor(v->cm, c), lp, rp);
		return;
	}

	/* rats, need general case anyway... */
	dovec(v, allcases(v, c), lp, rp);
}

/*
 - dovec - fill in arcs for each element of a cvec
 * This one has to handle the messy cases, like MCCEs and MCCE leaders.
 ^ static VOID dovec(struct vars *, struct cvec *, struct state *,
 ^	struct state *);
 */
static VOID
dovec(struct vars *v, struct cvec *cv, struct state *lp, struct state *rp)
{
	chr ch, from, to;
	celt ce;
	chr *p;
	int i;
	color co;
	struct cvec *leads;
	struct arc *a;
	struct arc *pa;		/* arc in prototype */
	struct state *s;
	struct state *ps;	/* state in prototype */

	/* need a place to store leaders, if any */
	if (nmcces(v) > 0) {
		assert(v->mcces != NULL);
		if (v->cv2 == NULL || v->cv2->nchrs < v->mcces->nchrs) {
			if (v->cv2 != NULL)
				free(v->cv2);
			v->cv2 = newcvec(v->mcces->nchrs, 0, v->mcces->nmcces);
			NOERR();
			leads = v->cv2;
		} else
			leads = clearcvec(v->cv2);
	} else
		leads = NULL;

	/* first, get the ordinary characters out of the way */
	for (p = cv->chrs, i = cv->nchrs; i > 0; p++, i--) {
		ch = *p;
		if (!ISCELEADER(v, ch)) {
			newarc(v->nfa, PLAIN, subcolor(v->cm, ch), lp, rp);
		        NOERR();
		} else {
			assert(singleton(v->cm, ch));
			assert(leads != NULL);
			if (!haschr(leads, ch))
				addchr(leads, ch);
		}
	}

	/* and the ranges */
	for (p = cv->ranges, i = cv->nranges; i > 0; p += 2, i--) {
		from = *p;
		to = *(p+1);
		while (from <= to && (ce = nextleader(v, from, to)) != NOCELT) {
			if (from < ce)
				subrange(v, from, ce - 1, lp, rp);
			assert(singleton(v->cm, ce));
			assert(leads != NULL);
			if (!haschr(leads, ce))
				addchr(leads, ce);
			from = ce + 1;
		}
		if (from <= to)
			subrange(v, from, to, lp, rp);
		NOERR();
	}

	if ((leads == NULL || leads->nchrs == 0) && cv->nmcces == 0)
		return;

	/* deal with the MCCE leaders */
	NOTE(REG_ULOCALE);
	for (p = leads->chrs, i = leads->nchrs; i > 0; p++, i--) {
		co = GETCOLOR(v->cm, *p);
		a = findarc(lp, PLAIN, co);
		if (a != NULL)
			s = a->to;
		else {
			s = newstate(v->nfa);
			NOERR();
			newarc(v->nfa, PLAIN, co, lp, s);
			NOERR();
		}
		pa = findarc(v->mccepbegin, PLAIN, co);
		assert(pa != NULL);
		ps = pa->to;
		newarc(v->nfa, '$', 1, s, rp);
		newarc(v->nfa, '$', 0, s, rp);
		colorcomplement(v->nfa, v->cm, AHEAD, ps, s, rp);
		NOERR();
	}

	/* and the MCCEs */
	for (i = 0; i < cv->nmcces; i++) {
		p = cv->mcces[i];
		assert(singleton(v->cm, *p));
		if (!singleton(v->cm, *p)) {
			ERR(REG_ASSERT);
			return;
		}
		ch = *p++;
		co = GETCOLOR(v->cm, ch);
		a = findarc(lp, PLAIN, co);
		if (a != NULL)
			s = a->to;
		else {
			s = newstate(v->nfa);
			NOERR();
			newarc(v->nfa, PLAIN, co, lp, s);
			NOERR();
		}
		assert(*p != 0);	/* at least two chars */
		assert(singleton(v->cm, *p));
		ch = *p++;
		co = GETCOLOR(v->cm, ch);
		assert(*p == 0);	/* and only two, for now */
		newarc(v->nfa, PLAIN, co, s, rp);
		NOERR();
	}
}

/*
 - nextleader - find next MCCE leader within range
 ^ static celt nextleader(struct vars *, pchr, pchr);
 */
static celt			/* NOCELT means none */
nextleader(struct vars *v, pchr from, pchr to)
{
	int i;
	chr *p;
	chr ch;
	celt it = NOCELT;

	if (v->mcces == NULL)
		return it;

	for (i = v->mcces->nchrs, p = v->mcces->chrs; i > 0; i--, p++) {
		ch = *p;
		if (from <= ch && ch <= to)
			if (it == NOCELT || ch < it)
				it = ch;
	}
	return it;
}

/*
 - wordchrs - set up word-chr list for word-boundary stuff, if needed
 * The list is kept as a bunch of arcs between two dummy states; it's
 * disposed of by the unreachable-states sweep in NFA optimization.
 * Does NEXT().  Must not be called from any unusual lexical context.
 * This should be reconciled with the \w etc. handling in lex.c, and
 * should be cleaned up to reduce dependencies on input scanning.
 ^ static VOID wordchrs(struct vars *);
 */
static VOID
wordchrs(struct vars *v)
{
	struct state *left;
	struct state *right;

	if (v->wordchrs != NULL) {
		NEXT();		/* for consistency */
		return;
	}

	left = newstate(v->nfa);
	right = newstate(v->nfa);
	NOERR();
	/* fine point:  implemented with [::], and lexer will set REG_ULOCALE */
	lexword(v);
	NEXT();
	assert(v->savenow != NULL && SEE('['));
	bracket(v, left, right);
	assert((v->savenow != NULL && SEE(']')) || ISERR());
	NEXT();
	NOERR();
	v->wordchrs = left;
}

/*
 - subre - allocate a subre
 ^ static struct subre *subre(struct vars *, int, int, struct state *,
 ^	struct state *);
 */
static struct subre *
subre(struct vars *v, int op, int flags, struct state *begin, struct state *end)
{
	struct subre *ret;

	ret = v->treefree;
	if (ret != NULL)
		v->treefree = ret->left;
	else {
		ret = (struct subre *)MALLOC(sizeof(struct subre));
		if (ret == NULL) {
			ERR(REG_ESPACE);
			return NULL;
		}
		ret->chain = v->treechain;
		v->treechain = ret;
	}

	assert(strchr("|.b(=", op) != NULL);

	ret->op = op;
	ret->flags = flags;
	ret->retry = 0;
	ret->subno = 0;
	ret->min = ret->max = 1;
	ret->left = NULL;
	ret->right = NULL;
	ret->begin = begin;
	ret->end = end;
	ZAPCNFA(ret->cnfa);

	return ret;
}

/*
 - freesubre - free a subRE subtree
 ^ static VOID freesubre(struct vars *, struct subre *);
 */
static VOID
freesubre(struct vars *v, struct subre *sr)
{
	if (sr == NULL)
		return;

	if (sr->left != NULL)
		freesubre(v, sr->left);
	if (sr->right != NULL)
		freesubre(v, sr->right);

	freesrnode(v, sr);
}

/*
 - freesrnode - free one node in a subRE subtree
 ^ static VOID freesrnode(struct vars *, struct subre *);
 */
static VOID
freesrnode(struct vars *v, struct subre *sr)
{
	if (sr == NULL)
		return;

	if (!NULLCNFA(sr->cnfa))
		freecnfa(&sr->cnfa);
	sr->flags = 0;

	if (v != NULL) {
		sr->left = v->treefree;
		v->treefree = sr;
	} else
		FREE(sr);
}

/*
 - optst - optimize a subRE subtree
 ^ static VOID optst(struct vars *, struct subre *);
 */
static VOID
optst(struct vars *v, struct subre *t)
{
	if (t == NULL)
		return;

	/* recurse through children */
	if (t->left != NULL)
		optst(v, t->left);
	if (t->right != NULL)
		optst(v, t->right);
}

/*
 - numst - number tree nodes (assigning retry indexes)
 ^ static int numst(struct subre *, int);
 */
static int			/* next number */
numst(struct subre *t, int start)
{
	int i;

	assert(t != NULL);

	i = start;
	t->retry = (short)i++;
	if (t->left != NULL)
		i = numst(t->left, i);
	if (t->right != NULL)
		i = numst(t->right, i);
	return i;
}

/*
 - markst - mark tree nodes as INUSE
 ^ static VOID markst(struct subre *);
 */
static VOID
markst(struct subre *t)
{
	assert(t != NULL);

	t->flags |= INUSE;
	if (t->left != NULL)
		markst(t->left);
	if (t->right != NULL)
		markst(t->right);
}

/*
 - cleanst - free any tree nodes not marked INUSE
 ^ static VOID cleanst(struct vars *);
 */
static VOID
cleanst(struct vars *v)
{
	struct subre *t;
	struct subre *next;

	for (t = v->treechain; t != NULL; t = next) {
		next = t->chain;
		if (!(t->flags&INUSE))
			FREE(t);
	}
	v->treechain = NULL;
	v->treefree = NULL;		/* just on general principles */
}

/*
 - nfatree - turn a subRE subtree into a tree of compacted NFAs
 ^ static long nfatree(struct vars *, struct subre *, FILE *);
 */
static long			/* optimize results from top node */
nfatree(struct vars *v, struct subre *t, FILE *f)
{
	assert(t != NULL && t->begin != NULL);

	if (t->left != NULL)
		(DISCARD)nfatree(v, t->left, f);
	if (t->right != NULL)
		(DISCARD)nfatree(v, t->right, f);

	return nfanode(v, t, f);
}

/*
 - nfanode - do one NFA for nfatree
 ^ static long nfanode(struct vars *, struct subre *, FILE *);
 */
static long			/* optimize results */
nfanode(struct vars *v, struct subre *t, FILE *f)
{
	struct nfa *nfa;
	long ret = 0;

	assert(t->begin != NULL);

#ifdef REG_DEBUG
	{
	char idbuf[50];
	if (f != NULL)
		fprintf(f, "\n\n\n========= TREE NODE %s ==========\n",
						stid(t, idbuf, sizeof(idbuf)));
	}
#endif
	nfa = newnfa(v, v->cm, v->nfa);
	NOERRZ();
	dupnfa(nfa, t->begin, t->end, nfa->init, nfa->final);
	if (!ISERR()) {
		specialcolors(nfa);
		ret = optimize(nfa, f);
	}
	if (!ISERR())
		compact(nfa, &t->cnfa);

	freenfa(nfa);
	return ret;
}

/*
 - newlacon - allocate a lookahead-constraint subRE
 ^ static int newlacon(struct vars *, struct state *, struct state *, int);
 */
static int			/* lacon number */
newlacon(struct vars *v, struct state *begin, struct state *end, int pos)
{
	int n;
	struct subre *sub;

	if (v->nlacons == 0) {
		v->lacons = (struct subre *)MALLOC(2 * sizeof(struct subre));
		n = 1;		/* skip 0th */
		v->nlacons = 2;
	} else {
		v->lacons = (struct subre *)REALLOC(v->lacons,
					(v->nlacons+1)*sizeof(struct subre));
		n = v->nlacons++;
	}
	if (v->lacons == NULL) {
		ERR(REG_ESPACE);
		return 0;
	}
	sub = &v->lacons[n];
	sub->begin = begin;
	sub->end = end;
	sub->subno = pos;
	ZAPCNFA(sub->cnfa);
	return n;
}

/*
 - freelacons - free lookahead-constraint subRE vector
 ^ static VOID freelacons(struct subre *, int);
 */
static VOID
freelacons(struct subre *subs, int n)
{
	struct subre *sub;
	int i;

	assert(n > 0);
	for (sub = subs + 1, i = n - 1; i > 0; sub++, i--)	/* no 0th */
		if (!NULLCNFA(sub->cnfa))
			freecnfa(&sub->cnfa);
	FREE(subs);
}

/*
 - rfree - free a whole RE (insides of regfree)
 ^ static VOID rfree(regex_t *);
 */
static VOID
rfree(regex_t *re)
{
	struct guts *g;

	if (re == NULL || re->re_magic != REMAGIC)
		return;

	re->re_magic = 0;	/* invalidate RE */
	g = (struct guts *)re->re_guts;
	re->re_guts = NULL;
	re->re_fns = NULL;
	g->magic = 0;
	freecm(&g->cmap);
	if (g->tree != NULL)
		freesubre((struct vars *)NULL, g->tree);
	if (g->lacons != NULL)
		freelacons(g->lacons, g->nlacons);
	if (!NULLCNFA(g->search))
		freecnfa(&g->search);
	FREE(g);
}

/*
 - dump - dump an RE in human-readable form
 ^ static VOID dump(regex_t *, FILE *);
 */
#ifdef REG_DEBUG
static VOID
dump(regex_t *re, FILE *f)
{
	struct guts *g;
	int i;

	if (re->re_magic != REMAGIC)
		fprintf(f, "bad magic number (0x%x not 0x%x)\n", re->re_magic,
								REMAGIC);
	if (re->re_guts == NULL) {
		fprintf(f, "NULL guts!!!\n");
		return;
	}
	g = (struct guts *)re->re_guts;
	if (g->magic != GUTSMAGIC)
		fprintf(f, "bad guts magic number (0x%x not 0x%x)\n", g->magic,
								GUTSMAGIC);

	fprintf(f, "\n\n\n========= DUMP ==========\n");
	fprintf(f, "nsub %d, info 0%lo, csize %d, ntree %d\n",
		re->re_nsub, re->re_info, re->re_csize, g->ntree);

	dumpcolors(&g->cmap, f);
	if (!NULLCNFA(g->search)) {
		printf("\nsearch:\n");
		dumpcnfa(&g->search, f);
	}
	for (i = 1; i < g->nlacons; i++) {
		fprintf(f, "\nla%d (%s):\n", i,
				(g->lacons[i].subno) ? "positive" : "negative");
		dumpcnfa(&g->lacons[i].cnfa, f);
	}
	fprintf(f, "\n");
	dumpst(g->tree, f, 0);
}

/*
 - dumpst - dump a subRE tree
 ^ static VOID dumpst(struct subre *, FILE *, int);
 */
static VOID
dumpst(struct subre *t, FILE *f, int nfapresent)
{
	if (t == NULL)
		fprintf(f, "null tree\n");
	else
		stdump(t, f, nfapresent);
	fflush(f);
}

/*
 - stdump - recursive guts of dumpst
 ^ static VOID stdump(struct subre *, FILE *, int);
 */
static VOID
stdump(struct subre *t, FILE *f, int nfapresent)
{
	char idbuf[50];

	fprintf(f, "%s. `%c'", stid(t, idbuf, sizeof(idbuf)), t->op);
	if (t->flags&LONGER)
		fprintf(f, " longest");
	if (t->flags&SHORTER)
		fprintf(f, " shortest");
	if (t->flags&MIXED)
		fprintf(f, " hasmixed");
	if (t->flags&CAP)
		fprintf(f, " hascapture");
	if (t->flags&BACKR)
		fprintf(f, " hasbackref");
	if (!(t->flags&INUSE))
		fprintf(f, " UNUSED");
	if (t->subno != 0)
		fprintf(f, " (#%d)", t->subno);
	if (t->min != 1 || t->max != 1) {
		fprintf(f, " {%d,", t->min);
		if (t->max != INFINITY)
			fprintf(f, "%d", t->max);
		fprintf(f, "}");
	}
	if (nfapresent)
		fprintf(f, " %ld-%ld", (long)t->begin->no, (long)t->end->no);
	if (t->left != NULL)
		fprintf(f, " L:%s", stid(t->left, idbuf, sizeof(idbuf)));
	if (t->right != NULL)
		fprintf(f, " R:%s", stid(t->right, idbuf, sizeof(idbuf)));
	if (!NULLCNFA(t->cnfa)) {
		fprintf(f, "\n");
		dumpcnfa(&t->cnfa, f);
		fprintf(f, "\n");
	}
	if (t->left != NULL)
		stdump(t->left, f, nfapresent);
	if (t->right != NULL)
		stdump(t->right, f, nfapresent);
}

/*
 - stid - identify a subtree node for dumping
 ^ static char *stid(struct subre *, char *, size_t);
 */
static char *			/* points to buf or constant string */
stid(struct subre *t, char *buf, size_t bufsize)
{
	/* big enough for hex int or decimal t->retry? */
	if (bufsize < sizeof(void*)*2 + 3 || bufsize < sizeof(t->retry)*3 + 1)
		return "unable";
	if (t->retry != 0)
		sprintf(buf, "%d", t->retry);
	else
		sprintf(buf, "%p", t);
	return buf;
}
#endif /*REG_DEBUG*/

#include "regc_lex.c"
#include "regc_color.c"
#include "regc_nfa.c"
#include "regc_cvec.c"
#include "regc_locale.c"
