/****************************************************************
Copyright (C) Lucent Technologies 1997
All Rights Reserved

Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name Lucent Technologies or any of
its entities not be used in advertising or publicity pertaining
to distribution of the software without specific, written prior
permission.

LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.
****************************************************************/

/* lasciate ogne speranza, voi ch'intrate. */

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#define	DEBUG

#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "awk.h"
#include "awkgram.h"

#define	HAT	(NCHARS+2)	/* matches ^ in regular expr */
				/* NCHARS is 2**n */
#define MAXLIN 22

#define type(v)		(v)->nobj	/* badly overloaded here */
#define info(v)		(v)->ntype	/* badly overloaded here */
#define left(v)		(v)->narg[0]
#define right(v)	(v)->narg[1]
#define parent(v)	(v)->nnext

#define LEAF	case CCL: case NCCL: case CHAR: case DOT: case FINAL: case ALL:
#define ELEAF	case EMPTYRE:		/* empty string in regexp */
#define UNARY	case STAR: case PLUS: case QUEST:

/* encoding in tree Nodes:
	leaf (CCL, NCCL, CHAR, DOT, FINAL, ALL, EMPTYRE):
		left is index, right contains value or pointer to value
	unary (STAR, PLUS, QUEST): left is child, right is null
	binary (CAT, OR): left and right are children
	parent contains pointer to parent
*/


int	*setvec;
int	*tmpset;
int	maxsetvec = 0;

int	rtok;		/* next token in current re */
int	rlxval;
static const uschar	*rlxstr;
static const uschar	*prestr;	/* current position in current re */
static const uschar	*lastre;	/* origin of last re */

static	int setcnt;
static	int poscnt;

uschar	*patbeg;
int	patlen;

#define	NFA	128	/* cache this many dynamic fa's */
fa	*fatab[NFA];
int	nfatab	= 0;	/* entries in fatab */

static void
resizesetvec(const char *msg)
{
	if (maxsetvec == 0)
		maxsetvec = MAXLIN;
	else
		maxsetvec *= 4;
	setvec = realloc(setvec, maxsetvec * sizeof(*setvec));
	tmpset = realloc(tmpset, maxsetvec * sizeof(*tmpset));
	if (setvec == 0 || tmpset == 0)
	    overflo(msg);
}

static void
resize_state(fa *f, int state)
{
	void *p;
	int i, new_count;

	if (++state < f->state_count)
		return;

	new_count = state + 10; /* needs to be tuned */

	p = realloc(f->gototab, new_count * sizeof(f->gototab[0]));
	if (p == NULL)
		goto out;
	f->gototab = p;

	p = realloc(f->out, new_count * sizeof(f->out[0]));
	if (p == NULL)
		goto out;
	f->out = p;

	p = realloc(f->posns, new_count * sizeof(f->posns[0]));
	if (p == NULL)
		goto out;
	f->posns = p;

	for (i = f->state_count; i < new_count; ++i) {
		f->gototab[i] = calloc(1, NCHARS * sizeof (**f->gototab));
		if (f->gototab[i] == NULL)
			goto out;
		f->out[i]  = 0;
		f->posns[i] = NULL;
	}
	f->state_count = new_count;
	return;
out:
	overflo("out of memory in resize_state");
}

fa *makedfa(const char *s, int anchor)	/* returns dfa for reg expr s */
{
	int i, use, nuse;
	fa *pfa;
	static int now = 1;

	if (setvec == 0)	/* first time through any RE */
		resizesetvec("out of space initializing makedfa");

	if (compile_time)	/* a constant for sure */
		return mkdfa(s, anchor);
	for (i = 0; i < nfatab; i++)	/* is it there already? */
		if (fatab[i]->anchor == anchor
		  && strcmp((const char *) fatab[i]->restr, s) == 0) {
			fatab[i]->use = now++;
			return fatab[i];
		}
	pfa = mkdfa(s, anchor);
	if (nfatab < NFA) {	/* room for another */
		fatab[nfatab] = pfa;
		fatab[nfatab]->use = now++;
		nfatab++;
		return pfa;
	}
	use = fatab[0]->use;	/* replace least-recently used */
	nuse = 0;
	for (i = 1; i < nfatab; i++)
		if (fatab[i]->use < use) {
			use = fatab[i]->use;
			nuse = i;
		}
	freefa(fatab[nuse]);
	fatab[nuse] = pfa;
	pfa->use = now++;
	return pfa;
}

fa *mkdfa(const char *s, int anchor)	/* does the real work of making a dfa */
				/* anchor = 1 for anchored matches, else 0 */
{
	Node *p, *p1;
	fa *f;

	p = reparse(s);
	p1 = op2(CAT, op2(STAR, op2(ALL, NIL, NIL), NIL), p);
		/* put ALL STAR in front of reg.  exp. */
	p1 = op2(CAT, p1, op2(FINAL, NIL, NIL));
		/* put FINAL after reg.  exp. */

	poscnt = 0;
	penter(p1);	/* enter parent pointers and leaf indices */
	if ((f = calloc(1, sizeof(*f) + poscnt*sizeof(rrow))) == NULL)
		overflo("out of space for fa");
	f->accept = poscnt-1;	/* penter has computed number of positions in re */
	cfoll(f, p1);	/* set up follow sets */
	freetr(p1);
	resize_state(f, 1);
	if ((f->posns[0] = calloc(1, *(f->re[0].lfollow)*sizeof(int))) == NULL)
			overflo("out of space in makedfa");
	if ((f->posns[1] = calloc(1, sizeof(int))) == NULL)
		overflo("out of space in makedfa");
	*f->posns[1] = 0;
	f->initstat = makeinit(f, anchor);
	f->anchor = anchor;
	f->restr = (uschar *) tostring(s);
	return f;
}

int makeinit(fa *f, int anchor)
{
	int i, k;

	resize_state(f, 2);
	f->curstat = 2;
	f->out[2] = 0;
	k = *(f->re[0].lfollow);
	xfree(f->posns[2]);			
	if ((f->posns[2] = calloc(1, (k+1)*sizeof(int))) == NULL)
		overflo("out of space in makeinit");
	for (i=0; i <= k; i++) {
		(f->posns[2])[i] = (f->re[0].lfollow)[i];
	}
	if ((f->posns[2])[1] == f->accept)
		f->out[2] = 1;
	for (i=0; i < NCHARS; i++)
		f->gototab[2][i] = 0;
	f->curstat = cgoto(f, 2, HAT);
	if (anchor) {
		*f->posns[2] = k-1;	/* leave out position 0 */
		for (i=0; i < k; i++) {
			(f->posns[0])[i] = (f->posns[2])[i];
		}

		f->out[0] = f->out[2];
		if (f->curstat != 2) {
			resize_state(f, f->curstat);
			--(*f->posns[f->curstat]);
		}
	}
	return f->curstat;
}

void penter(Node *p)	/* set up parent pointers and leaf indices */
{
	switch (type(p)) {
	ELEAF
	LEAF
		info(p) = poscnt;
		poscnt++;
		break;
	UNARY
		penter(left(p));
		parent(left(p)) = p;
		break;
	case CAT:
	case OR:
		penter(left(p));
		penter(right(p));
		parent(left(p)) = p;
		parent(right(p)) = p;
		break;
	default:	/* can't happen */
		FATAL("can't happen: unknown type %d in penter", type(p));
		break;
	}
}

void freetr(Node *p)	/* free parse tree */
{
	switch (type(p)) {
	ELEAF
	LEAF
		xfree(p);
		break;
	UNARY
		freetr(left(p));
		xfree(p);
		break;
	case CAT:
	case OR:
		freetr(left(p));
		freetr(right(p));
		xfree(p);
		break;
	default:	/* can't happen */
		FATAL("can't happen: unknown type %d in freetr", type(p));
		break;
	}
}

/* in the parsing of regular expressions, metacharacters like . have */
/* to be seen literally;  \056 is not a metacharacter. */

int hexstr(const uschar **pp)	/* find and eval hex string at pp, return new p */
{			/* only pick up one 8-bit byte (2 chars) */
	const uschar *p;
	int n = 0;
	int i;

	for (i = 0, p = *pp; i < 2 && isxdigit(*p); i++, p++) {
		if (isdigit(*p))
			n = 16 * n + *p - '0';
		else if (*p >= 'a' && *p <= 'f')
			n = 16 * n + *p - 'a' + 10;
		else if (*p >= 'A' && *p <= 'F')
			n = 16 * n + *p - 'A' + 10;
	}
	*pp = p;
	return n;
}

#define isoctdigit(c) ((c) >= '0' && (c) <= '7')	/* multiple use of arg */

int quoted(const uschar **pp)	/* pick up next thing after a \\ */
			/* and increment *pp */
{
	const uschar *p = *pp;
	int c;

	if ((c = *p++) == 't')
		c = '\t';
	else if (c == 'n')
		c = '\n';
	else if (c == 'f')
		c = '\f';
	else if (c == 'r')
		c = '\r';
	else if (c == 'b')
		c = '\b';
	else if (c == '\\')
		c = '\\';
	else if (c == 'x') {	/* hexadecimal goo follows */
		c = hexstr(&p);	/* this adds a null if number is invalid */
	} else if (isoctdigit(c)) {	/* \d \dd \ddd */
		int n = c - '0';
		if (isoctdigit(*p)) {
			n = 8 * n + *p++ - '0';
			if (isoctdigit(*p))
				n = 8 * n + *p++ - '0';
		}
		c = n;
	} /* else */
		/* c = c; */
	*pp = p;
	return c;
}

char *cclenter(const char *argp)	/* add a character class */
{
	int i, c, c2;
	const uschar *p = (const uschar *) argp;
	const uschar *op;
	uschar *bp;
	static uschar *buf = 0;
	static int bufsz = 100;

	op = p;
	if (buf == 0 && (buf = malloc(bufsz)) == NULL)
		FATAL("out of space for character class [%.10s...] 1", p);
	bp = buf;
	for (i = 0; (c = *p++) != 0; ) {
		if (c == '\\') {
			c = quoted(&p);
		} else if (c == '-' && i > 0 && bp[-1] != 0) {
			if (*p != 0) {
				c = bp[-1];
				c2 = *p++;
				if (c2 == '\\')
					c2 = quoted(&p);
				if (c > c2) {	/* empty; ignore */
					bp--;
					i--;
					continue;
				}
				while (c < c2) {
					if (!adjbuf(&buf, &bufsz, bp-buf+2, 100, &bp, "cclenter1"))
						FATAL("out of space for character class [%.10s...] 2", p);
					*bp++ = ++c;
					i++;
				}
				continue;
			}
		}
		if (!adjbuf(&buf, &bufsz, bp-buf+2, 100, &bp, "cclenter2"))
			FATAL("out of space for character class [%.10s...] 3", p);
		*bp++ = c;
		i++;
	}
	*bp = 0;
	dprintf( ("cclenter: in = |%s|, out = |%s|\n", op, buf) );
	free(__UNCONST(op));
	return (char *) tostring((char *) buf);
}

void overflo(const char *s)
{
	FATAL("regular expression too big: %.30s...", s);
}

void cfoll(fa *f, Node *v)	/* enter follow set of each leaf of vertex v into lfollow[leaf] */
{
	int i;
	int *p;

	switch (type(v)) {
	ELEAF
	LEAF
		f->re[info(v)].ltype = type(v);
		f->re[info(v)].lval.np = right(v);
		while (f->accept >= maxsetvec) /* guessing here! */
			resizesetvec("out of space in cfoll()");
		for (i = 0; i <= f->accept; i++)
			setvec[i] = 0;
		setcnt = 0;
		follow(v);	/* computes setvec and setcnt */
		if ((p = calloc(1, (setcnt+1)*sizeof(int))) == NULL)
			overflo("out of space building follow set");
		f->re[info(v)].lfollow = p;
		*p = setcnt;
		for (i = f->accept; i >= 0; i--)
			if (setvec[i] == 1)
				*++p = i;
		break;
	UNARY
		cfoll(f,left(v));
		break;
	case CAT:
	case OR:
		cfoll(f,left(v));
		cfoll(f,right(v));
		break;
	default:	/* can't happen */
		FATAL("can't happen: unknown type %d in cfoll", type(v));
	}
}

int first(Node *p)	/* collects initially active leaves of p into setvec */
			/* returns 0 if p matches empty string */
{
	int b, lp;

	switch (type(p)) {
	ELEAF
	LEAF
		lp = info(p);	/* look for high-water mark of subscripts */
		while (setcnt >= maxsetvec || lp >= maxsetvec) /* guessing here! */
			resizesetvec("out of space in first()");
		if (type(p) == EMPTYRE) {
			setvec[lp] = 0;
			return(0);
		}
		if (setvec[lp] != 1) {
			setvec[lp] = 1;
			setcnt++;
		}
		if (type(p) == CCL && (*(char *) right(p)) == '\0')
			return(0);		/* empty CCL */
		else return(1);
	case PLUS:
		if (first(left(p)) == 0) return(0);
		return(1);
	case STAR:
	case QUEST:
		first(left(p));
		return(0);
	case CAT:
		if (first(left(p)) == 0 && first(right(p)) == 0) return(0);
		return(1);
	case OR:
		b = first(right(p));
		if (first(left(p)) == 0 || b == 0) return(0);
		return(1);
	}
	FATAL("can't happen: unknown type %d in first", type(p));	/* can't happen */
	return(-1);
}

void follow(Node *v)	/* collects leaves that can follow v into setvec */
{
	Node *p;

	if (type(v) == FINAL)
		return;
	p = parent(v);
	switch (type(p)) {
	case STAR:
	case PLUS:
		first(v);
		follow(p);
		return;

	case OR:
	case QUEST:
		follow(p);
		return;

	case CAT:
		if (v == left(p)) {	/* v is left child of p */
			if (first(right(p)) == 0) {
				follow(p);
				return;
			}
		} else		/* v is right child */
			follow(p);
		return;
	}
}

int member(int c, const char *sarg)	/* is c in s? */
{
	const uschar *s = (const uschar *) sarg;

	while (*s)
		if (c == *s++)
			return(1);
	return(0);
}

int match(fa *f, const char *p0)	/* shortest match ? */
{
	int s, ns;
	const uschar *p = (const uschar *) p0;

	s = f->initstat;
	assert (s < f->state_count);

	if (f->out[s])
		return(1);
	do {
		/* assert(*p < NCHARS); */
		if ((ns = f->gototab[s][*p]) != 0)
			s = ns;
		else
			s = cgoto(f, s, *p);

		assert (s < f->state_count);

		if (f->out[s])
			return(1);
	} while (*p++ != 0);
	return(0);
}

int pmatch(fa *f, const char *p0)	/* longest match, for sub */
{
	int s, ns;
	uschar *p = __UNCONST(p0);
	uschar *q;

	s = f->initstat;
	assert(s < f->state_count);
	patbeg = p;
	patlen = -1;
	do {
		q = p;
		do {
			if (f->out[s])		/* final state */
				patlen = q-p;
			/* assert(*q < NCHARS); */
			if ((ns = f->gototab[s][*q]) != 0)
				s = ns;
			else
				s = cgoto(f, s, *q);

			assert(s < f->state_count);

			if (s == 1) {	/* no transition */
				if (patlen >= 0) {
					patbeg = p;
					return(1);
				}
				else
					goto nextin;	/* no match */
			}
		} while (*q++ != 0);
		if (f->out[s])
			patlen = q-p-1;	/* don't count $ */
		if (patlen >= 0) {
			patbeg = p;
			return(1);
		}
	nextin:
		s = 2;
	} while (*p++ != 0);
	return (0);
}

int nematch(fa *f, const char *p0)	/* non-empty match, for sub */
{
	int s, ns;
	uschar *p = __UNCONST(p0);
	uschar *q;

	s = f->initstat;
	assert(s < f->state_count);

	patlen = -1;
	while (*p) {
		q = p;
		do {
			if (f->out[s])		/* final state */
				patlen = q-p;
			/* assert(*q < NCHARS); */
			if ((ns = f->gototab[s][*q]) != 0)
				s = ns;
			else
				s = cgoto(f, s, *q);

			assert(s < f->state_count);

			if (s == 1) {	/* no transition */
				if (patlen > 0) {
					patbeg = p;
					return(1);
				} else
					goto nnextin;	/* no nonempty match */
			}
		} while (*q++ != 0);
		if (f->out[s])
			patlen = q-p-1;	/* don't count $ */
		if (patlen > 0 ) {
			patbeg = p;
			return(1);
		}
	nnextin:
		s = 2;
		p++;
	}
	return (0);
}


/*
 * NAME
 *     fnematch
 *
 * DESCRIPTION
 *     A stream-fed version of nematch which transfers characters to a
 *     null-terminated buffer. All characters up to and including the last
 *     character of the matching text or EOF are placed in the buffer. If
 *     a match is found, patbeg and patlen are set appropriately.
 *
 * RETURN VALUES
 *     0    No match found.
 *     1    Match found.
 */  

int fnematch(fa *pfa, FILE *f, uschar **pbuf, int *pbufsize, int quantum)	
{
	uschar *buf = *pbuf;
	int bufsize = *pbufsize;
	int c, i, j, k, ns, s;

	s = pfa->initstat;
	assert(s < pfa->state_count);
	patlen = 0;

	/*
	 * All indices relative to buf.
	 * i <= j <= k <= bufsize
	 *
	 * i: origin of active substring
	 * j: current character
	 * k: destination of next getc()
	 */
	i = -1, k = 0;
        do {
		j = i++;
		do {
			if (++j == k) {
				if (k == bufsize)
					if (!adjbuf(&buf, &bufsize, bufsize+1, quantum, 0, "fnematch"))
						FATAL("stream '%.30s...' too long", buf);	
				buf[k++] = (c = getc(f)) != EOF ? c : 0;
			}
			c = buf[j];
			/* assert(c < NCHARS); */

			if ((ns = pfa->gototab[s][c]) != 0)
				s = ns;
			else
				s = cgoto(pfa, s, c);
			assert(s < pfa->state_count);

			if (pfa->out[s]) {	/* final state */
				patlen = j - i + 1;
				if (c == 0)	/* don't count $ */
					patlen--;
			}
		} while (buf[j] && s != 1);
		s = 2;
	} while (buf[i] && !patlen);

	/* adjbuf() may have relocated a resized buffer. Inform the world. */
	*pbuf = buf;
	*pbufsize = bufsize;

	if (patlen) {
		patbeg = buf + i;
		/*
		 * Under no circumstances is the last character fed to
		 * the automaton part of the match. It is EOF's nullbyte,
		 * or it sent the automaton into a state with no further
		 * transitions available (s==1), or both. Room for a
		 * terminating nullbyte is guaranteed.
		 *
		 * ungetc any chars after the end of matching text
		 * (except for EOF's nullbyte, if present) and null
		 * terminate the buffer.
		 */
		do
			if (buf[--k] && ungetc(buf[k], f) == EOF)
				FATAL("unable to ungetc '%c'", buf[k]);	
		while (k > i + patlen);
		buf[k] = 0;
		return 1;
	}
	else
		return 0;
}

Node *reparse(const char *p)	/* parses regular expression pointed to by p */
{			/* uses relex() to scan regular expression */
	Node *np;

	dprintf( ("reparse <%s>\n", p) );
	lastre = prestr = (const uschar *) p;	/* prestr points to string to be parsed */
	rtok = relex();
	/* GNU compatibility: an empty regexp matches anything */
	if (rtok == '\0') {
		/* FATAL("empty regular expression"); previous */
		return(op2(EMPTYRE, NIL, NIL));
	}
	np = regexp();
	if (rtok != '\0')
		FATAL("syntax error in regular expression %s at %s", lastre, prestr);
	return(np);
}

Node *regexp(void)	/* top-level parse of reg expr */
{
	return (alt(concat(primary())));
}

Node *primary(void)
{
	Node *np;

	switch (rtok) {
	case CHAR:
		np = op2(CHAR, NIL, itonp(rlxval));
		rtok = relex();
		return (unary(np));
	case ALL:
		rtok = relex();
		return (unary(op2(ALL, NIL, NIL)));
	case EMPTYRE:
		rtok = relex();
		return (unary(op2(ALL, NIL, NIL)));
	case DOT:
		rtok = relex();
		return (unary(op2(DOT, NIL, NIL)));
	case CCL:
		np = op2(CCL, NIL, (Node*) cclenter((const char *) rlxstr));
		rtok = relex();
		return (unary(np));
	case NCCL:
		np = op2(NCCL, NIL, (Node *) cclenter((const char *) rlxstr));
		rtok = relex();
		return (unary(np));
	case '^':
		rtok = relex();
		return (unary(op2(CHAR, NIL, itonp(HAT))));
	case '$':
		rtok = relex();
		return (unary(op2(CHAR, NIL, NIL)));
	case '(':
		rtok = relex();
		if (rtok == ')') {	/* special pleading for () */
			rtok = relex();
			return unary(op2(CCL, NIL, (Node *) tostring("")));
		}
		np = regexp();
		if (rtok == ')') {
			rtok = relex();
			return (unary(np));
		}
		else
			FATAL("syntax error in regular expression %s at %s", lastre, prestr);
	default:
		FATAL("illegal primary in regular expression %s at %s", lastre, prestr);
	}
	return 0;	/*NOTREACHED*/
}

Node *concat(Node *np)
{
	switch (rtok) {
	case CHAR: case DOT: case ALL: case EMPTYRE: case CCL: case NCCL: case '$': case '(':
		return (concat(op2(CAT, np, primary())));
	}
	return (np);
}

Node *alt(Node *np)
{
	if (rtok == OR) {
		rtok = relex();
		return (alt(op2(OR, np, concat(primary()))));
	}
	return (np);
}

Node *unary(Node *np)
{
	switch (rtok) {
	case STAR:
		rtok = relex();
		return (unary(op2(STAR, np, NIL)));
	case PLUS:
		rtok = relex();
		return (unary(op2(PLUS, np, NIL)));
	case QUEST:
		rtok = relex();
		return (unary(op2(QUEST, np, NIL)));
	default:
		return (np);
	}
}

/*
 * Character class definitions conformant to the POSIX locale as
 * defined in IEEE P1003.1 draft 7 of June 2001, assuming the source
 * and operating character sets are both ASCII (ISO646) or supersets
 * thereof.
 *
 * Note that to avoid overflowing the temporary buffer used in
 * relex(), the expanded character class (prior to range expansion)
 * must be less than twice the size of their full name.
 */

/* Because isblank doesn't show up in any of the header files on any
 * system i use, it's defined here.  if some other locale has a richer
 * definition of "blank", define HAS_ISBLANK and provide your own
 * version.
 * the parentheses here are an attempt to find a path through the maze
 * of macro definition and/or function and/or version provided.  thanks
 * to nelson beebe for the suggestion; let's see if it works everywhere.
 */

/* #define HAS_ISBLANK */

static const struct charclass {
	const char *cc_name;
	int cc_namelen;
	int (*cc_func)(int);
} charclasses[] = {
	{ "alnum",	5,	isalnum },
	{ "alpha",	5,	isalpha },
#ifndef HAS_ISBLANK
	{ "blank",	5,	isspace }, /* was isblank */
#else
	{ "blank",	5,	isblank },
#endif
	{ "cntrl",	5,	iscntrl },
	{ "digit",	5,	isdigit },
	{ "graph",	5,	isgraph },
	{ "lower",	5,	islower },
	{ "print",	5,	isprint },
	{ "punct",	5,	ispunct },
	{ "space",	5,	isspace },
	{ "upper",	5,	isupper },
	{ "xdigit",	6,	isxdigit },
	{ NULL,		0,	NULL },
};


int relex(void)		/* lexical analyzer for reparse */
{
	int c, n;
	int cflag;
	static uschar *buf = 0;
	static int bufsz = 100;
	uschar *bp;
	const struct charclass *cc;
	int i;

	switch (c = *prestr++) {
	case '|': return OR;
	case '*': return STAR;
	case '+': return PLUS;
	case '?': return QUEST;
	case '.': return DOT;
	case '\0': prestr--; return '\0';
	case '^':
	case '$':
	case '(':
	case ')':
		return c;
	case '\\':
		rlxval = quoted(&prestr);
		return CHAR;
	default:
		rlxval = c;
		return CHAR;
	case '[': 
		if (buf == 0 && (buf = malloc(bufsz)) == NULL)
			FATAL("out of space in reg expr %.10s..", lastre);
		bp = buf;
		if (*prestr == '^') {
			cflag = 1;
			prestr++;
		}
		else
			cflag = 0;
		n = 2 * strlen((const char *) prestr)+1;
		if (!adjbuf(&buf, &bufsz, n, n, &bp, "relex1"))
			FATAL("out of space for reg expr %.10s...", lastre);
		for (; ; ) {
			if ((c = *prestr++) == '\\') {
				*bp++ = '\\';
				if ((c = *prestr++) == '\0')
					FATAL("nonterminated character class %.20s...", lastre);
				*bp++ = c;
			/* } else if (c == '\n') { */
			/* 	FATAL("newline in character class %.20s...", lastre); */
			} else if (c == '[' && *prestr == ':') {
				/* POSIX char class names, Dag-Erling Smorgrav, des@ofug.org */
				for (cc = charclasses; cc->cc_name; cc++)
					if (strncmp((const char *) prestr + 1, (const char *) cc->cc_name, cc->cc_namelen) == 0)
						break;
				if (cc->cc_name != NULL && prestr[1 + cc->cc_namelen] == ':' &&
				    prestr[2 + cc->cc_namelen] == ']') {
					prestr += cc->cc_namelen + 3;
					for (i = 1; i < NCHARS; i++) {
						if (!adjbuf(&buf, &bufsz, bp-buf+1, 100, &bp, "relex2"))
						    FATAL("out of space for reg expr %.10s...", lastre);
						if (cc->cc_func(i)) {
							*bp++ = i;
							n++;
						}
					}
				} else
					*bp++ = c;
			} else if (c == '\0') {
				FATAL("nonterminated character class %.20s", lastre);
			} else if (bp == buf) {	/* 1st char is special */
				*bp++ = c;
			} else if (c == ']') {
				*bp++ = 0;
				rlxstr = (uschar *) tostring((char *) buf);
				if (cflag == 0)
					return CCL;
				else
					return NCCL;
			} else
				*bp++ = c;
		}
	}
}

int cgoto(fa *f, int s, int c)
{
	int i, j, k;
	int *p, *q;

	assert(c == HAT || c < NCHARS);
	while (f->accept >= maxsetvec) 	/* guessing here! */
		resizesetvec("out of space in cgoto()");
	for (i = 0; i <= f->accept; i++)
		setvec[i] = 0;
	setcnt = 0;
	resize_state(f, s);
	/* compute positions of gototab[s,c] into setvec */
	p = f->posns[s];
	for (i = 1; i <= *p; i++) {
		if ((k = f->re[p[i]].ltype) != FINAL) {
			if ((k == CHAR && c == ptoi(f->re[p[i]].lval.np))
			 || (k == DOT && c != 0 && c != HAT)
			 || (k == ALL && c != 0)
			 || (k == EMPTYRE && c != 0)
			 || (k == CCL && member(c, (char *) f->re[p[i]].lval.up))
			 || (k == NCCL && !member(c, (char *) f->re[p[i]].lval.up) && c != 0 && c != HAT)) {
				q = f->re[p[i]].lfollow;
				for (j = 1; j <= *q; j++) {
					if (q[j] >= maxsetvec)
						resizesetvec("cgoto overflow");
					if (setvec[q[j]] == 0) {
						setcnt++;
						setvec[q[j]] = 1;
					}
				}
			}
		}
	}
	/* determine if setvec is a previous state */
	tmpset[0] = setcnt;
	j = 1;
	for (i = f->accept; i >= 0; i--)
		if (setvec[i]) {
			tmpset[j++] = i;
		}

	resize_state(f, f->curstat > s ? f->curstat : s);
	/* tmpset == previous state? */
	for (i = 1; i <= f->curstat; i++) {
		p = f->posns[i];
		if ((k = tmpset[0]) != p[0])
			goto different;
		for (j = 1; j <= k; j++)
			if (tmpset[j] != p[j])
				goto different;
		/* setvec is state i */
		if (c != HAT)
			f->gototab[s][c] = i;
		return i;
	  different:;
	}

	/* add tmpset to current set of states */
	++(f->curstat);
	resize_state(f, f->curstat);
	for (i = 0; i < NCHARS; i++)
		f->gototab[f->curstat][i] = 0;
	xfree(f->posns[f->curstat]);
	if ((p = calloc(1, (setcnt+1)*sizeof(int))) == NULL)
		overflo("out of space in cgoto");

	f->posns[f->curstat] = p;
	if (c != HAT)
		f->gototab[s][c] = f->curstat;
	for (i = 0; i <= setcnt; i++)
		p[i] = tmpset[i];
	if (setvec[f->accept])
		f->out[f->curstat] = 1;
	else
		f->out[f->curstat] = 0;
	return f->curstat;
}


void freefa(fa *f)	/* free a finite automaton */
{
	int i;

	if (f == NULL)
		return;
	for (i = 0; i < f->state_count; i++) {
		xfree(f->gototab[i])
		xfree(f->posns[i]);
	}
	for (i = 0; i <= f->accept; i++) {
		xfree(f->re[i].lfollow);
		if (f->re[i].ltype == CCL || f->re[i].ltype == NCCL)
			xfree((f->re[i].lval.np));
	}
	xfree(f->restr);
	xfree(f->out);
	xfree(f->posns);
	xfree(f->gototab);
	xfree(f);
}
