/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8   -*-│
│ vi: set noet ft=c ts=8 sw=8 fenc=utf-8                                   :vi │
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│ 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.                                                               │
│                                                                              │
╚─────────────────────────────────────────────────────────────────────────────*/
#define DEBUG
#include "libc/calls/calls.h"
#include "libc/mem/mem.h"
#include "libc/str/str.h"
#include "third_party/awk/awk.h"
#include "third_party/awk/awkgram.tab.h"

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

#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 const uschar	*lastatom;	/* origin of last Atom */
static const uschar	*starttok;
static const uschar 	*basestr;	/* starts with original, replaced during
				   repetition processing */
static const uschar 	*firstbasestr;

static	int setcnt;
static	int poscnt;

const char	*patbeg;
int	patlen;

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

static int *
intalloc(size_t n, const char *f)
{
	int *p = (int *) calloc(n, sizeof(int));
	if (p == NULL)
		overflo(f);
	return p;
}

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

static void
resize_state(fa *f, int state)
{
	unsigned int **p;
	uschar *p2;
	int **p3;
	int i, new_count;

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

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

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

	p2 = (uschar *) realloc(f->out, new_count * sizeof(f->out[0]));
	if (p2 == NULL)
		goto out;
	f->out = p2;

	p3 = (int **) realloc(f->posns, new_count * sizeof(f->posns[0]));
	if (p3 == NULL)
		goto out;
	f->posns = p3;

	for (i = f->state_count; i < new_count; ++i) {
		f->gototab[i] = (unsigned int *) calloc(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(__func__);
}

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

	if (setvec == NULL) {	/* first time through any RE */
		resizesetvec(__func__);
	}

	if (compile_time != RUNNING)	/* 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, bool anchor)	/* does the real work of making a dfa */
				/* anchor = true for anchored matches, else false */
{
	Node *p, *p1;
	fa *f;

	firstbasestr = (const uschar *) s;
	basestr = firstbasestr;
	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 = (fa *) calloc(1, sizeof(fa) + poscnt * sizeof(rrow))) == NULL)
		overflo(__func__);
	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);
	f->posns[0] = intalloc(*(f->re[0].lfollow), __func__);
	f->posns[1] = intalloc(1, __func__);
	*f->posns[1] = 0;
	f->initstat = makeinit(f, anchor);
	f->anchor = anchor;
	f->restr = (uschar *) tostring(s);
	if (firstbasestr != basestr) {
		if (basestr)
			xfree(basestr);
	}
	return f;
}

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

	f->curstat = 2;
	f->out[2] = 0;
	k = *(f->re[0].lfollow);
	xfree(f->posns[2]);
	f->posns[2] = intalloc(k + 1,  __func__);
	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)
			--(*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;
	case ZERO:
		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
	case ZERO:
		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 == 'v')
		c = '\v';
	else if (c == 'a')
		c = '\a';
	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 *op, *p = (const uschar *) argp;
	uschar *bp;
	static uschar *buf = NULL;
	static int bufsz = 100;

	op = p;
	if (buf == NULL && (buf = (uschar *) 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((char **) &buf, &bufsz, bp-buf+2, 100, (char **) &bp, "cclenter1"))
						FATAL("out of space for character class [%.10s...] 2", p);
					*bp++ = ++c;
					i++;
				}
				continue;
			}
		}
		if (!adjbuf((char **) &buf, &bufsz, bp-buf+2, 100, (char **) &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);
	xfree(op);
	return (char *) tostring((char *) buf);
}

void overflo(const char *s)
{
	FATAL("regular expression too big: out of space in %.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(__func__);
		}
		for (i = 0; i <= f->accept; i++)
			setvec[i] = 0;
		setcnt = 0;
		follow(v);	/* computes setvec and setcnt */
		p = intalloc(setcnt + 1, __func__);
		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;
	case ZERO:
		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(__func__);
		}
		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 */
		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);
	case ZERO:
		return 0;
	}
	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);
		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;
	const uschar *p = (const uschar *) p0;
	const uschar *q;

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

	patbeg = (const char *)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 = (const char *) 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 = (const char *) p;
			return(1);
		}
	nextin:
		s = 2;
	} while (*p++);
	return (0);
}

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

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

	patbeg = (const char *)p;
	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);
			if (s == 1) {	/* no transition */
				if (patlen > 0) {
					patbeg = (const char *) 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 = (const char *) 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
 *     false    No match found.
 *     true     Match found.
 */

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

	s = pfa->initstat;
	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((char **) &buf, &bufsize, bufsize+1, quantum, 0, "fnematch"))
						FATAL("stream '%.30s...' too long", buf);
				buf[k++] = (c = getc(f)) != EOF ? c : 0;
			}
			c = (uschar)buf[j];
			/* assert(c < NCHARS); */

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

			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 = (char *) 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 true;
	}
	else
		return false;
}

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;
	int savelastatom;

	switch (rtok) {
	case CHAR:
		lastatom = starttok;
		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(EMPTYRE, NIL, NIL)));
	case DOT:
		lastatom = starttok;
		rtok = relex();
		return (unary(op2(DOT, NIL, NIL)));
	case CCL:
		np = op2(CCL, NIL, (Node*) cclenter((const char *) rlxstr));
		lastatom = starttok;
		rtok = relex();
		return (unary(np));
	case NCCL:
		np = op2(NCCL, NIL, (Node *) cclenter((const char *) rlxstr));
		lastatom = starttok;
		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 '(':
		lastatom = starttok;
		savelastatom = starttok - basestr; /* Retain over recursion */
		rtok = relex();
		if (rtok == ')') {	/* special pleading for () */
			rtok = relex();
			return unary(op2(CCL, NIL, (Node *) tostring("")));
		}
		np = regexp();
		if (rtok == ')') {
			lastatom = basestr + savelastatom; /* Restore */
			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 CCL: case NCCL: case '$': case '(':
		return (concat(op2(CAT, np, primary())));
	case EMPTYRE:
		rtok = relex();
		return (concat(op2(CAT, op2(CCL, NIL, (Node *) tostring("")),
				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)));
	case ZERO:
		rtok = relex();
		return (unary(op2(ZERO, 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.
 */

static const struct charclass {
	const char *cc_name;
	int cc_namelen;
	int (*cc_func)(int);
} charclasses[] = {
	{ "alnum",	5,	isalnum },
	{ "alpha",	5,	isalpha },
	{ "blank",	5,	isblank },
	{ "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 },
};

#define REPEAT_SIMPLE		0
#define REPEAT_PLUS_APPENDED	1
#define REPEAT_WITH_Q		2
#define REPEAT_ZERO		3

static int
replace_repeat(const uschar *reptok, int reptoklen, const uschar *atom,
	       int atomlen, int firstnum, int secondnum, int special_case)
{
	int i, j;
	uschar *buf = 0;
	int ret = 1;
	int init_q = (firstnum == 0);		/* first added char will be ? */
	int n_q_reps = secondnum-firstnum;	/* m>n, so reduce until {1,m-n} left  */
	int prefix_length = reptok - basestr;	/* prefix includes first rep	*/
	int suffix_length = strlen((const char *) reptok) - reptoklen;	/* string after rep specifier	*/
	int size = prefix_length +  suffix_length;

	if (firstnum > 1) {	/* add room for reps 2 through firstnum */
		size += atomlen*(firstnum-1);
	}

	/* Adjust size of buffer for special cases */
	if (special_case == REPEAT_PLUS_APPENDED) {
		size++;		/* for the final + */
	} else if (special_case == REPEAT_WITH_Q) {
		size += init_q + (atomlen+1)* (n_q_reps-init_q);
	} else if (special_case == REPEAT_ZERO) {
		size += 2;	/* just a null ERE: () */
	}
	if ((buf = (uschar *) malloc(size + 1)) == NULL)
		FATAL("out of space in reg expr %.10s..", lastre);
	memcpy(buf, basestr, prefix_length);	/* copy prefix	*/
	j = prefix_length;
	if (special_case == REPEAT_ZERO) {
		j -= atomlen;
		buf[j++] = '(';
		buf[j++] = ')';
	}
	for (i = 1; i < firstnum; i++) {	/* copy x reps 	*/
		memcpy(&buf[j], atom, atomlen);
		j += atomlen;
	}
	if (special_case == REPEAT_PLUS_APPENDED) {
		buf[j++] = '+';
	} else if (special_case == REPEAT_WITH_Q) {
		if (init_q)
			buf[j++] = '?';
		for (i = init_q; i < n_q_reps; i++) {	/* copy x? reps */
			memcpy(&buf[j], atom, atomlen);
			j += atomlen;
			buf[j++] = '?';
		}
	}
	memcpy(&buf[j], reptok+reptoklen, suffix_length);
	j += suffix_length;
	buf[j] = '\0';
	/* free old basestr */
	if (firstbasestr != basestr) {
		if (basestr)
			xfree(basestr);
	}
	basestr = buf;
	prestr  = buf + prefix_length;
	if (special_case == REPEAT_ZERO) {
		prestr  -= atomlen;
		ret++;
	}
	return ret;
}

static int repeat(const uschar *reptok, int reptoklen, const uschar *atom,
		  int atomlen, int firstnum, int secondnum)
{
	/*
	   In general, the repetition specifier or "bound" is replaced here
	   by an equivalent ERE string, repeating the immediately previous atom
	   and appending ? and + as needed. Note that the first copy of the
	   atom is left in place, except in the special_case of a zero-repeat
	   (i.e., {0}).
	 */
	if (secondnum < 0) {	/* means {n,} -> repeat n-1 times followed by PLUS */
		if (firstnum < 2) {
			/* 0 or 1: should be handled before you get here */
			FATAL("internal error");
		} else {
			return replace_repeat(reptok, reptoklen, atom, atomlen,
				firstnum, secondnum, REPEAT_PLUS_APPENDED);
		}
	} else if (firstnum == secondnum) {	/* {n} or {n,n} -> simply repeat n-1 times */
		if (firstnum == 0) {	/* {0} or {0,0} */
			/* This case is unusual because the resulting
			   replacement string might actually be SMALLER than
			   the original ERE */
			return replace_repeat(reptok, reptoklen, atom, atomlen,
					firstnum, secondnum, REPEAT_ZERO);
		} else {		/* (firstnum >= 1) */
			return replace_repeat(reptok, reptoklen, atom, atomlen,
					firstnum, secondnum, REPEAT_SIMPLE);
		}
	} else if (firstnum < secondnum) {	/* {n,m} -> repeat n-1 times then alternate  */
		/*  x{n,m}  =>  xx...x{1, m-n+1}  =>  xx...x?x?x?..x?	*/
		return replace_repeat(reptok, reptoklen, atom, atomlen,
					firstnum, secondnum, REPEAT_WITH_Q);
	} else {	/* Error - shouldn't be here (n>m) */
		FATAL("internal error");
	}
	return 0;
}

int relex(void)		/* lexical analyzer for reparse */
{
	int c, n;
	int cflag;
	static uschar *buf = NULL;
	static int bufsz = 100;
	uschar *bp;
	const struct charclass *cc;
	int i;
	int num, m;
	bool commafound, digitfound;
	const uschar *startreptok;
	static int parens = 0;

rescan:
	starttok = prestr;

	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 '$':
		return c;
	case '(':
		parens++;
		return c;
	case ')':
		if (parens) {
			parens--;
			return c;
		}
		/* unmatched close parenthesis; per POSIX, treat as literal */
		rlxval = c;
		return CHAR;
	case '\\':
		rlxval = quoted(&prestr);
		return CHAR;
	default:
		rlxval = c;
		return CHAR;
	case '[':
		if (buf == NULL && (buf = (uschar *) 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((char **) &buf, &bufsz, n, n, (char **) &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;
					/*
					 * BUG: We begin at 1, instead of 0, since we
					 * would otherwise prematurely terminate the
					 * string for classes like [[:cntrl:]]. This
					 * means that we can't match the NUL character,
					 * not without first adapting the entire
					 * program to track each string's length.
					 */
					for (i = 1; i <= UCHAR_MAX; i++) {
						if (!adjbuf((char **) &buf, &bufsz, bp-buf+2, 100, (char **) &bp, "relex2"))
						    FATAL("out of space for reg expr %.10s...", lastre);
						if (cc->cc_func(i)) {
							/* escape backslash */
							if (i == '\\') {
								*bp++ = '\\';
								n++;
							}

							*bp++ = i;
							n++;
						}
					}
				} else
					*bp++ = c;
			} else if (c == '[' && *prestr == '.') {
				char collate_char;
				prestr++;
				collate_char = *prestr++;
				if (*prestr == '.' && prestr[1] == ']') {
					prestr += 2;
					/* Found it: map via locale TBD: for
					   now, simply return this char.  This
					   is sufficient to pass conformance
					   test awk.ex 156
					 */
					if (*prestr == ']') {
						prestr++;
						rlxval = collate_char;
						return CHAR;
					}
				}
			} else if (c == '[' && *prestr == '=') {
				char equiv_char;
				prestr++;
				equiv_char = *prestr++;
				if (*prestr == '=' && prestr[1] == ']') {
					prestr += 2;
					/* Found it: map via locale TBD: for now
					   simply return this char. This is
					   sufficient to pass conformance test
					   awk.ex 156
					 */
					if (*prestr == ']') {
						prestr++;
						rlxval = equiv_char;
						return CHAR;
					}
				}
			} 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;
		}
		break;
	case '{':
		if (isdigit(*(prestr))) {
			num = 0;	/* Process as a repetition */
			n = -1; m = -1;
			commafound = false;
			digitfound = false;
			startreptok = prestr-1;
			/* Remember start of previous atom here ? */
		} else {        	/* just a { char, not a repetition */
			rlxval = c;
			return CHAR;
                }
		for (; ; ) {
			if ((c = *prestr++) == '}') {
				if (commafound) {
					if (digitfound) { /* {n,m} */
						m = num;
						if (m < n)
							FATAL("illegal repetition expression: class %.20s",
								lastre);
						if (n == 0 && m == 1) {
							return QUEST;
						}
					} else {	/* {n,} */
						if (n == 0)
							return STAR;
						else if (n == 1)
							return PLUS;
					}
				} else {
					if (digitfound) { /* {n} same as {n,n} */
						n = num;
						m = num;
					} else {	/* {} */
						FATAL("illegal repetition expression: class %.20s",
							lastre);
					}
				}
				if (repeat(starttok, prestr-starttok, lastatom,
					   startreptok - lastatom, n, m) > 0) {
					if (n == 0 && m == 0) {
						return ZERO;
					}
					/* must rescan input for next token */
					goto rescan;
				}
				/* Failed to replace: eat up {...} characters
				   and treat like just PLUS */
				return PLUS;
			} else if (c == '\0') {
				FATAL("nonterminated character class %.20s",
					lastre);
			} else if (isdigit(c)) {
				num = 10 * num + c - '0';
				digitfound = true;
			} else if (c == ',') {
				if (commafound)
					FATAL("illegal repetition expression: class %.20s",
						lastre);
				/* looking for {n,} or {n,m} */
				commafound = true;
				n = num;
				digitfound = false; /* reset */
				num = 0;
			} else {
				FATAL("illegal repetition expression: class %.20s",
					lastre);
			}
		}
		break;
	}
	return 0; /* [jart] why wasn't this here? */
}

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

	assert(c == HAT || c < NCHARS);
	while (f->accept >= maxsetvec) {	/* guessing here! */
		resizesetvec(__func__);
	}
	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(__func__);
					}
					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]);
	p = intalloc(setcnt + 1, __func__);

	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])
	for (i = 0; i <= f->curstat; 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);
}