uclibc-ng/libc/misc/regex/rx.c

/*	Copyright (C) 1992, 1993, 1994, 1995 Free Software Foundation, Inc.

This file is part of the librx library.

Librx is free software; you can redistribute it and/or modify it under
the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

Librx is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU Library General Public
License along with this software; see the file COPYING.LIB.  If not,
write to the Free Software Foundation, 675 Mass Ave, Cambridge, MA
02139, USA.  */

/* NOTE!!!  AIX is so losing it requires this to be the first thing in the 
 * file. 
 * Do not put ANYTHING before it!  
 */
#if !defined (__GNUC__) && defined (_AIX)
#pragma alloca
#endif

/* To make linux happy? */
#ifndef	_GNU_SOURCE
#define	_GNU_SOURCE
#endif


#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#ifndef isgraph
#define isgraph(c) (isprint (c) && !isspace (c))
#endif
#ifndef isblank
#define isblank(c) ((c) == ' ' || (c) == '\t')
#endif

#include <sys/types.h>

#undef MAX
#undef MIN
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))

typedef char boolean;

#define false 0
#define true 1

#ifndef __GCC__
#undef __inline__
#define __inline__
#endif

/* Emacs already defines alloca, sometimes.  */
#ifndef alloca

/* Make alloca work the best possible way.  */
#ifdef __GNUC__
#define alloca __builtin_alloca
#else							/* not __GNUC__ */
#if HAVE_ALLOCA_H
#include <alloca.h>
#else							/* not __GNUC__ or HAVE_ALLOCA_H */
#ifndef _AIX					/* Already did AIX, up at the top.  */
char *alloca();
#endif							/* not _AIX */
#endif							/* not HAVE_ALLOCA_H */
#endif							/* not __GNUC__ */

#endif							/* not alloca */

/* Memory management and stuff for emacs. */

#define CHARBITS 8
#define remalloc(M, S) (M ? realloc (M, S) : malloc (S))


/* Should we use malloc or alloca?  If REGEX_MALLOC is not defined, we
 * use `alloca' instead of `malloc' for the backtracking stack.
 *
 * Emacs will die miserably if we don't do this.
 */

#ifdef REGEX_MALLOC
#define REGEX_ALLOCATE malloc
#else							/* not REGEX_MALLOC  */
#define REGEX_ALLOCATE alloca
#endif							/* not REGEX_MALLOC */


#ifdef RX_WANT_RX_DEFS
#define RX_DECL extern
#define RX_DEF_QUAL
#else
#define RX_WANT_RX_DEFS
#define RX_DECL static
#define RX_DEF_QUAL static
#endif

#include <regex.h>
#undef RX_DECL
#define RX_DECL RX_DEF_QUAL


/*
 *  Prototypes.
 */
#ifdef __STDC__
RX_DECL struct rx_hash_item
*rx_hash_find(struct rx_hash *, unsigned long,

			  void *, struct rx_hash_rules *);
RX_DECL struct rx_hash_item
*rx_hash_find(struct rx_hash *, unsigned long,

			  void *, struct rx_hash_rules *);
RX_DECL struct rx_hash_item
*rx_hash_store(struct rx_hash *, unsigned long,

			   void *, struct rx_hash_rules *);
RX_DECL void rx_hash_free(struct rx_hash_item *, struct rx_hash_rules *);
RX_DECL void rx_free_hash_table(struct rx_hash *, rx_hash_freefn,

								struct rx_hash_rules *);
RX_DECL rx_Bitset rx_cset(struct rx *);
RX_DECL rx_Bitset rx_copy_cset(struct rx *, rx_Bitset);
RX_DECL void rx_free_cset(struct rx *, rx_Bitset);
static struct rx_hash_item
*compiler_hash_item_alloc(struct rx_hash_rules *, void *);
static struct rx_hash
*compiler_hash_alloc(struct rx_hash_rules *);
static void compiler_free_hash(struct rx_hash *, struct rx_hash_rules *);
static void compiler_free_hash_item(struct rx_hash_item *,

									struct rx_hash_rules *);
RX_DECL struct rexp_node
*rexp_node(struct rx *, enum rexp_node_type);
RX_DECL struct rexp_node
*rx_mk_r_cset(struct rx *, rx_Bitset);
RX_DECL struct rexp_node
*rx_mk_r_concat(struct rx *, struct rexp_node *, struct rexp_node *);
RX_DECL struct rexp_node
*rx_mk_r_alternate(struct rx *, struct rexp_node *, struct rexp_node *);
RX_DECL struct rexp_node
*rx_mk_r_alternate(struct rx *, struct rexp_node *, struct rexp_node *);
RX_DECL struct rexp_node
*rx_mk_r_opt(struct rx *, struct rexp_node *);
RX_DECL struct rexp_node
*rx_mk_r_star(struct rx *, struct rexp_node *);
RX_DECL struct rexp_node
*rx_mk_r_2phase_star(struct rx *, struct rexp_node *, struct rexp_node *);
RX_DECL struct rexp_node
*rx_mk_r_side_effect(struct rx *, rx_side_effect);

//RX_DECL struct rexp_node
//            *rx_mk_r_data              (struct rx *, void *);
RX_DECL void rx_free_rexp(struct rx *, struct rexp_node *);
RX_DECL struct rexp_node
*rx_copy_rexp(struct rx *, struct rexp_node *);
RX_DECL struct rx_nfa_state
*rx_nfa_state(struct rx *);
RX_DECL void rx_free_nfa_state(struct rx_nfa_state *);
RX_DECL struct rx_nfa_state
*rx_id_to_nfa_state(struct rx *, int);
RX_DECL struct rx_nfa_edge
*rx_nfa_edge(struct rx *, enum rx_nfa_etype,

			 struct rx_nfa_state *, struct rx_nfa_state *);
RX_DECL void rx_free_nfa_edge(struct rx_nfa_edge *);
static struct rx_possible_future
*rx_possible_future(struct rx *, struct rx_se_list *);
static void rx_free_possible_future(struct rx_possible_future *);
RX_DECL void rx_free_nfa(struct rx *);
RX_DECL int rx_build_nfa(struct rx *, struct rexp_node *,
						 struct rx_nfa_state **, struct rx_nfa_state **);
RX_DECL void rx_name_nfa_states(struct rx *);
static int se_list_cmp(void *, void *);
static int se_list_equal(void *, void *);
static struct rx_se_list
*hash_cons_se_prog(struct rx *, struct rx_hash *,

				   void *, struct rx_se_list *);
static struct rx_se_list
*hash_se_prog(struct rx *, struct rx_hash *, struct rx_se_list *);
static int nfa_set_cmp(void *, void *);
static int nfa_set_equal(void *, void *);
static struct rx_nfa_state_set
*nfa_set_cons(struct rx *, struct rx_hash *,

			  struct rx_nfa_state *, struct rx_nfa_state_set *);
static struct rx_nfa_state_set
*nfa_set_enjoin(struct rx *, struct rx_hash *,

				struct rx_nfa_state *, struct rx_nfa_state_set *);
#endif

#ifndef emacs

#ifdef SYNTAX_TABLE
extern char *re_syntax_table;
#else							/* not SYNTAX_TABLE */

#ifndef RX_WANT_RX_DEFS
RX_DECL char re_syntax_table[CHAR_SET_SIZE];
#endif

#ifdef __STDC__
static void init_syntax_once(void)
#else
static void init_syntax_once()
#endif
{
	register int c;
	static int done = 0;

	if (done)
		return;

	bzero(re_syntax_table, sizeof re_syntax_table);

	for (c = 'a'; c <= 'z'; c++)
		re_syntax_table[c] = Sword;

	for (c = 'A'; c <= 'Z'; c++)
		re_syntax_table[c] = Sword;

	for (c = '0'; c <= '9'; c++)
		re_syntax_table[c] = Sword;

	re_syntax_table['_'] = Sword;

	done = 1;
}
#endif							/* not SYNTAX_TABLE */
#endif							/* not emacs */

/* Compile with `-DRX_DEBUG' and use the following flags.
 *
 * Debugging flags:
 *   	rx_debug - print information as a regexp is compiled
 * 	rx_debug_trace - print information as a regexp is executed
 */

#ifdef RX_DEBUG

int rx_debug_compile = 0;
int rx_debug_trace = 0;
static struct re_pattern_buffer *dbug_rxb = 0;


/*
 * More Prototypes
 */
#ifdef __STDC__
typedef void (*side_effect_printer) (struct rx *, void *, FILE *);
static void print_cset(struct rx *, rx_Bitset, FILE *);
static void print_rexp(struct rx *, struct rexp_node *, int,
					   side_effect_printer, FILE *);
static void print_nfa(struct rx *, struct rx_nfa_state *,
					  side_effect_printer, FILE *);
static void re_seprint(struct rx *, void *, FILE *);
void print_compiled_pattern(struct re_pattern_buffer *);
void print_fastmap(char *);
#else
typedef void (*side_effect_printer) ();
static void print_cset();
#endif

#ifdef __STDC__
static void
print_rexp(struct rx *rx,
		   struct rexp_node *node, int depth,
		   side_effect_printer seprint, FILE * fp)
#else
static void print_rexp(rx, node, depth, seprint, fp)
struct rx *rx;
struct rexp_node *node;
int depth;
side_effect_printer seprint;
FILE *fp;
#endif
{
	if (!node)
		return;
	else {
		switch (node->type) {
		case r_cset:
		{
			fprintf(fp, "%*s", depth, "");
			print_cset(rx, node->params.cset, fp);
			fputc('\n', fp);
			break;
		}

		case r_opt:
		case r_star:
			fprintf(fp, "%*s%s\n", depth, "",
					node->type == r_opt ? "opt" : "star");
			print_rexp(rx, node->params.pair.left, depth + 3, seprint, fp);
			break;

		case r_2phase_star:
			fprintf(fp, "%*s2phase star\n", depth, "");
			print_rexp(rx, node->params.pair.right, depth + 3, seprint,
					   fp);
			print_rexp(rx, node->params.pair.left, depth + 3, seprint, fp);
			break;


		case r_alternate:
		case r_concat:
			fprintf(fp, "%*s%s\n", depth, "",
					node->type == r_alternate ? "alt" : "concat");
			print_rexp(rx, node->params.pair.left, depth + 3, seprint, fp);
			print_rexp(rx, node->params.pair.right, depth + 3, seprint,
					   fp);
			break;
		case r_side_effect:
			fprintf(fp, "%*sSide effect: ", depth, "");
			seprint(rx, node->params.side_effect, fp);
			fputc('\n', fp);
		}
	}
}

#ifdef __STDC__
static void
print_nfa(struct rx *rx,
		  struct rx_nfa_state *n, side_effect_printer seprint, FILE * fp)
#else
static void print_nfa(rx, n, seprint, fp)
struct rx *rx;
struct rx_nfa_state *n;
side_effect_printer seprint;
FILE *fp;
#endif
{
	while (n) {
		struct rx_nfa_edge *e = n->edges;
		struct rx_possible_future *ec = n->futures;

		fprintf(fp, "node %d %s\n", n->id,
				n->is_final ? "final" : (n->is_start ? "start" : ""));
		while (e) {
			fprintf(fp, "   edge to %d, ", e->dest->id);
			switch (e->type) {
			case ne_epsilon:
				fprintf(fp, "epsilon\n");
				break;
			case ne_side_effect:
				fprintf(fp, "side effect ");
				seprint(rx, e->params.side_effect, fp);
				fputc('\n', fp);
				break;
			case ne_cset:
				fprintf(fp, "cset ");
				print_cset(rx, e->params.cset, fp);
				fputc('\n', fp);
				break;
			}
			e = e->next;
		}

		while (ec) {
			int x;
			struct rx_nfa_state_set *s;
			struct rx_se_list *l;

			fprintf(fp, "   eclosure to {");
			for (s = ec->destset; s; s = s->cdr)
				fprintf(fp, "%d ", s->car->id);
			fprintf(fp, "} (");
			for (l = ec->effects; l; l = l->cdr) {
				seprint(rx, l->car, fp);
				fputc(' ', fp);
			}
			fprintf(fp, ")\n");
			ec = ec->next;
		}
		n = n->next;
	}
}

static char *efnames[] = {
	"bogon",
	"re_se_try",
	"re_se_pushback",
	"re_se_push0",
	"re_se_pushpos",
	"re_se_chkpos",
	"re_se_poppos",
	"re_se_at_dot",
	"re_se_syntax",
	"re_se_not_syntax",
	"re_se_begbuf",
	"re_se_hat",
	"re_se_wordbeg",
	"re_se_wordbound",
	"re_se_notwordbound",
	"re_se_wordend",
	"re_se_endbuf",
	"re_se_dollar",
	"re_se_fail",
};

static char *efnames2[] = {
	"re_se_win",
	"re_se_lparen",
	"re_se_rparen",
	"re_se_backref",
	"re_se_iter",
	"re_se_end_iter",
	"re_se_tv"
};

static char *inx_names[] = {
	"rx_backtrack_point",
	"rx_do_side_effects",
	"rx_cache_miss",
	"rx_next_char",
	"rx_backtrack",
	"rx_error_inx",
	"rx_num_instructions"
};


#ifdef __STDC__
static void re_seprint(struct rx *rx, void *effect, FILE * fp)
#else
static void re_seprint(rx, effect, fp)
struct rx *rx;
void *effect;
FILE *fp;
#endif
{
	if ((int) effect < 0)
		fputs(efnames[-(int) effect], fp);
	else if (dbug_rxb) {
		struct re_se_params *p = &dbug_rxb->se_params[(int) effect];

		fprintf(fp, "%s(%d,%d)", efnames2[p->se], p->op1, p->op2);
	} else
		fprintf(fp, "[complex op # %d]", (int) effect);
}

/* These are so the regex.c regression tests will compile. */
void print_compiled_pattern(rxb)
struct re_pattern_buffer *rxb;
{
}

void print_fastmap(fm)
char *fm;
{
}

#endif							/* RX_DEBUG */



/* This page: Bitsets.  Completely unintersting. */

//RX_DECL int   rx_bitset_is_equal        (int, rx_Bitset, rx_Bitset);
RX_DECL int rx_bitset_is_subset(int, rx_Bitset, rx_Bitset);

//RX_DECL int   rx_bitset_empty           (int, rx_Bitset);
RX_DECL void rx_bitset_null(int, rx_Bitset);
RX_DECL void rx_bitset_complement(int, rx_Bitset);
RX_DECL void rx_bitset_complement(int, rx_Bitset);
RX_DECL void rx_bitset_assign(int, rx_Bitset, rx_Bitset);
RX_DECL void rx_bitset_union(int, rx_Bitset, rx_Bitset);
RX_DECL void rx_bitset_intersection(int, rx_Bitset, rx_Bitset);
RX_DECL void rx_bitset_difference(int, rx_Bitset, rx_Bitset);

//RX_DECL void  rx_bitset_revdifference   (int, rx_Bitset, rx_Bitset);
#ifdef emacs
RX_DECL void rx_bitset_xor(int, rx_Bitset, rx_Bitset);
#endif
RX_DECL unsigned long rx_bitset_hash(int, rx_Bitset);

#if 0
#ifdef __STDC__
RX_DECL int rx_bitset_is_equal(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL int rx_bitset_is_equal(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x;
	RX_subset s = b[0];

	b[0] = ~a[0];

	for (x = rx_bitset_numb_subsets(size) - 1; a[x] == b[x]; --x);

	b[0] = s;
	return !x && s == a[0];
}
#endif

#ifdef __STDC__
RX_DECL int rx_bitset_is_subset(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL int rx_bitset_is_subset(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x = rx_bitset_numb_subsets(size) - 1;

	while (x-- && (a[x] & b[x]) == a[x]);
	return x == -1;
}

#if 0
#ifdef __STDC__
RX_DECL int rx_bitset_empty(int size, rx_Bitset set)
#else
RX_DECL int rx_bitset_empty(size, set)
int size;
rx_Bitset set;
#endif
{
	int x;
	RX_subset s = set[0];

	set[0] = 1;
	for (x = rx_bitset_numb_subsets(size) - 1; !set[x]; --x);
	set[0] = s;
	return !s;
}
#endif

#ifdef __STDC__
RX_DECL void rx_bitset_null(int size, rx_Bitset b)
#else
RX_DECL void rx_bitset_null(size, b)
int size;
rx_Bitset b;
#endif
{
	bzero(b, rx_sizeof_bitset(size));
}


#ifdef __STDC__
RX_DECL void rx_bitset_universe(int size, rx_Bitset b)
#else
RX_DECL void rx_bitset_universe(size, b)
int size;
rx_Bitset b;
#endif
{
	int x = rx_bitset_numb_subsets(size);

	while (x--)
		*b++ = ~(RX_subset) 0;
}


#ifdef __STDC__
RX_DECL void rx_bitset_complement(int size, rx_Bitset b)
#else
RX_DECL void rx_bitset_complement(size, b)
int size;
rx_Bitset b;
#endif
{
	int x = rx_bitset_numb_subsets(size);

	while (x--) {
		*b = ~*b;
		++b;
	}
}


#ifdef __STDC__
RX_DECL void rx_bitset_assign(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL void rx_bitset_assign(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x;

	for (x = rx_bitset_numb_subsets(size) - 1; x >= 0; --x)
		a[x] = b[x];
}

#ifdef __STDC__
RX_DECL void rx_bitset_union(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL void rx_bitset_union(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x;

	for (x = rx_bitset_numb_subsets(size) - 1; x >= 0; --x)
		a[x] |= b[x];
}


#ifdef __STDC__
RX_DECL void rx_bitset_intersection(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL void rx_bitset_intersection(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x;

	for (x = rx_bitset_numb_subsets(size) - 1; x >= 0; --x)
		a[x] &= b[x];
}


#ifdef __STDC__
RX_DECL void rx_bitset_difference(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL void rx_bitset_difference(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x;

	for (x = rx_bitset_numb_subsets(size) - 1; x >= 0; --x)
		a[x] &= ~b[x];
}


#if 0
#ifdef __STDC__
RX_DECL void rx_bitset_revdifference(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL void rx_bitset_revdifference(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x;

	for (x = rx_bitset_numb_subsets(size) - 1; x >= 0; --x)
		a[x] = ~a[x] & b[x];
}
#endif


#ifdef emacs
#ifdef __STDC__
RX_DECL void rx_bitset_xor(int size, rx_Bitset a, rx_Bitset b)
#else
RX_DECL void rx_bitset_xor(size, a, b)
int size;
rx_Bitset a;
rx_Bitset b;
#endif
{
	int x;

	for (x = rx_bitset_numb_subsets(size) - 1; x >= 0; --x)
		a[x] ^= b[x];
}
#endif


#ifdef __STDC__
RX_DECL unsigned long rx_bitset_hash(int size, rx_Bitset b)
#else
RX_DECL unsigned long rx_bitset_hash(size, b)
int size;
rx_Bitset b;
#endif
{
	int x;
	unsigned long hash = (unsigned long) rx_bitset_hash;

	for (x = rx_bitset_numb_subsets(size) - 1; x >= 0; --x)
		hash ^= rx_bitset_subset_val(b, x);

	return hash;
}

RX_DECL RX_subset rx_subset_singletons[RX_subset_bits] = {
	0x1,
	0x2,
	0x4,
	0x8,
	0x10,
	0x20,
	0x40,
	0x80,
	0x100,
	0x200,
	0x400,
	0x800,
	0x1000,
	0x2000,
	0x4000,
	0x8000,
	0x10000,
	0x20000,
	0x40000,
	0x80000,
	0x100000,
	0x200000,
	0x400000,
	0x800000,
	0x1000000,
	0x2000000,
	0x4000000,
	0x8000000,
	0x10000000,
	0x20000000,
	0x40000000,
	0x80000000
};

#ifdef RX_DEBUG

#ifdef __STDC__
static void print_cset(struct rx *rx, rx_Bitset cset, FILE * fp)
#else
static void print_cset(rx, cset, fp)
struct rx *rx;
rx_Bitset cset;
FILE *fp;
#endif
{
	int x;

	fputc('[', fp);
	for (x = 0; x < rx->local_cset_size; ++x)
		if (RX_bitset_member(cset, x)) {
			if (isprint(x))
				fputc(x, fp);
			else
				fprintf(fp, "\\0%o ", x);
		}
	fputc(']', fp);
}

#endif							/*  RX_DEBUG */



static unsigned long rx_hash_masks[4] = {
	0x12488421,
	0x96699669,
	0xbe7dd7eb,
	0xffffffff
};


/* Hash tables */
#ifdef __STDC__
RX_DECL struct rx_hash_item *rx_hash_find(struct rx_hash *table,
										  unsigned long hash,
										  void *value,
										  struct rx_hash_rules *rules)
#else
RX_DECL struct rx_hash_item *rx_hash_find(table, hash, value, rules)
struct rx_hash *table;
unsigned long hash;
void *value;
struct rx_hash_rules *rules;
#endif
{
	rx_hash_eq eq = rules->eq;
	int maskc = 0;
	long mask = rx_hash_masks[0];
	int bucket = (hash & mask) % 13;

	while (table->children[bucket]) {
		table = table->children[bucket];
		++maskc;
		mask = rx_hash_masks[maskc];
		bucket = (hash & mask) % 13;
	}

	{
		struct rx_hash_item *it = table->buckets[bucket];

		while (it)
			if (eq(it->data, value))
				return it;
			else
				it = it->next_same_hash;
	}

	return 0;
}

#ifdef __STDC__
RX_DECL struct rx_hash_item *rx_hash_store(struct rx_hash *table,
										   unsigned long hash,
										   void *value,
										   struct rx_hash_rules *rules)
#else
RX_DECL struct rx_hash_item *rx_hash_store(table, hash, value, rules)
struct rx_hash *table;
unsigned long hash;
void *value;
struct rx_hash_rules *rules;
#endif
{
	rx_hash_eq eq = rules->eq;
	int maskc = 0;
	long mask = rx_hash_masks[0];
	int bucket = (hash & mask) % 13;
	int depth = 0;

	while (table->children[bucket]) {
		table = table->children[bucket];
		++maskc;
		mask = rx_hash_masks[maskc];
		bucket = (hash & mask) % 13;
		++depth;
	}

	{
		struct rx_hash_item *it = table->buckets[bucket];

		while (it)
			if (eq(it->data, value))
				return it;
			else
				it = it->next_same_hash;
	}

	{
		if ((depth < 3)
			&& (table->bucket_size[bucket] >= 4)) {
			struct rx_hash *newtab = ((struct rx_hash *)
									   rules->hash_alloc(rules));

			if (!newtab)
				goto add_to_bucket;
			bzero(newtab, sizeof(*newtab));
			newtab->parent = table;
			{
				struct rx_hash_item *them = table->buckets[bucket];
				unsigned long newmask = rx_hash_masks[maskc + 1];

				while (them) {
					struct rx_hash_item *save = them->next_same_hash;
					int new_buck = (them->hash & newmask) % 13;

					them->next_same_hash = newtab->buckets[new_buck];
					newtab->buckets[new_buck] = them;
					them->table = newtab;
					them = save;
					++newtab->bucket_size[new_buck];
					++newtab->refs;
				}
				table->refs =
					(table->refs - table->bucket_size[bucket] + 1);
				table->bucket_size[bucket] = 0;
				table->buckets[bucket] = 0;
				table->children[bucket] = newtab;
				table = newtab;
				bucket = (hash & newmask) % 13;
			}
		}
	}
  add_to_bucket:
	{
		struct rx_hash_item *it = ((struct rx_hash_item *)
								   rules->hash_item_alloc(rules, value));

		if (!it)
			return 0;
		it->hash = hash;
		it->table = table;
		/* DATA and BINDING are to be set in hash_item_alloc */
		it->next_same_hash = table->buckets[bucket];
		table->buckets[bucket] = it;
		++table->bucket_size[bucket];
		++table->refs;
		return it;
	}
}


#ifdef __STDC__
RX_DECL void
rx_hash_free(struct rx_hash_item *it, struct rx_hash_rules *rules)
#else
RX_DECL void rx_hash_free(it, rules)
struct rx_hash_item *it;
struct rx_hash_rules *rules;
#endif
{
	if (it) {
		struct rx_hash *table = it->table;
		unsigned long hash = it->hash;
		int depth = (table->parent
					 ? (table->parent->parent
						? (table->parent->parent->parent ? 3 : 2)
						: 1)
					 : 0);
		int bucket = (hash & rx_hash_masks[depth]) % 13;
		struct rx_hash_item **pos = &table->buckets[bucket];

		while (*pos != it)
			pos = &(*pos)->next_same_hash;
		*pos = it->next_same_hash;
		rules->free_hash_item(it, rules);
		--table->bucket_size[bucket];
		--table->refs;
		while (!table->refs && depth) {
			struct rx_hash *save = table;

			table = table->parent;
			--depth;
			bucket = (hash & rx_hash_masks[depth]) % 13;
			--table->refs;
			table->children[bucket] = 0;
			rules->free_hash(save, rules);
		}
	}
}

#ifdef __STDC__
RX_DECL void
rx_free_hash_table(struct rx_hash *tab, rx_hash_freefn freefn,
				   struct rx_hash_rules *rules)
#else
RX_DECL void rx_free_hash_table(tab, freefn, rules)
struct rx_hash *tab;
rx_hash_freefn freefn;
struct rx_hash_rules *rules;
#endif
{
	int x;

	for (x = 0; x < 13; ++x)
		if (tab->children[x]) {
			rx_free_hash_table(tab->children[x], freefn, rules);
			rules->free_hash(tab->children[x], rules);
		} else {
			struct rx_hash_item *them = tab->buckets[x];

			while (them) {
				struct rx_hash_item *that = them;

				them = that->next_same_hash;
				freefn(that);
				rules->free_hash_item(that, rules);
			}
		}
}



/* Utilities for manipulating bitset represntations of characters sets. */

#ifdef __STDC__
RX_DECL rx_Bitset rx_cset(struct rx *rx)
#else
RX_DECL rx_Bitset rx_cset(rx)
struct rx *rx;
#endif
{
	rx_Bitset b =

		(rx_Bitset) malloc(rx_sizeof_bitset(rx->local_cset_size));
	if (b)
		rx_bitset_null(rx->local_cset_size, b);
	return b;
}


#ifdef __STDC__
RX_DECL rx_Bitset rx_copy_cset(struct rx * rx, rx_Bitset a)
#else
RX_DECL rx_Bitset rx_copy_cset(rx, a)
struct rx *rx;
rx_Bitset a;
#endif
{
	rx_Bitset cs = rx_cset(rx);

	if (cs)
		rx_bitset_union(rx->local_cset_size, cs, a);

	return cs;
}


#ifdef __STDC__
RX_DECL void rx_free_cset(struct rx *rx, rx_Bitset c)
#else
RX_DECL void rx_free_cset(rx, c)
struct rx *rx;
rx_Bitset c;
#endif
{
	if (c)
		free((char *) c);
}


/* Hash table memory allocation policy for the regexp compiler */

#ifdef __STDC__
static struct rx_hash *compiler_hash_alloc(struct rx_hash_rules *rules)
#else
static struct rx_hash *compiler_hash_alloc(rules)
struct rx_hash_rules *rules;
#endif
{
	return (struct rx_hash *) malloc(sizeof(struct rx_hash));
}


#ifdef __STDC__
static struct rx_hash_item *compiler_hash_item_alloc(struct rx_hash_rules
													 *rules, void *value)
#else
static struct rx_hash_item *compiler_hash_item_alloc(rules, value)
struct rx_hash_rules *rules;
void *value;
#endif
{
	struct rx_hash_item *it;

	it = (struct rx_hash_item *) malloc(sizeof(*it));
	if (it) {
		it->data = value;
		it->binding = 0;
	}
	return it;
}

#ifdef __STDC__
static void
compiler_free_hash(struct rx_hash *tab, struct rx_hash_rules *rules)
#else
static void compiler_free_hash(tab, rules)
struct rx_hash *tab;
struct rx_hash_rules *rules;
#endif
{
	free((char *) tab);
}


#ifdef __STDC__
static void
compiler_free_hash_item(struct rx_hash_item *item,
						struct rx_hash_rules *rules)
#else
static void compiler_free_hash_item(item, rules)
struct rx_hash_item *item;
struct rx_hash_rules *rules;
#endif
{
	free((char *) item);
}


/* This page: REXP_NODE (expression tree) structures. */

#ifdef __STDC__
RX_DECL struct rexp_node *rexp_node(struct rx *rx,
									enum rexp_node_type type)
#else
RX_DECL struct rexp_node *rexp_node(rx, type)
struct rx *rx;
enum rexp_node_type type;
#endif
{
	struct rexp_node *n;

	n = (struct rexp_node *) malloc(sizeof(*n));
	if (n) {
		bzero(n, sizeof(*n));
		n->type = type;
	}
	return n;
}


/* free_rexp_node assumes that the bitset passed to rx_mk_r_cset
 * can be freed using rx_free_cset.
 */
#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_cset(struct rx *rx, rx_Bitset b)
#else
RX_DECL struct rexp_node *rx_mk_r_cset(rx, b)
struct rx *rx;
rx_Bitset b;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_cset);

	if (n)
		n->params.cset = b;
	return n;
}

#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_concat(struct rx *rx,
										 struct rexp_node *a,
										 struct rexp_node *b)
#else
RX_DECL struct rexp_node *rx_mk_r_concat(rx, a, b)
struct rx *rx;
struct rexp_node *a;
struct rexp_node *b;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_concat);

	if (n) {
		n->params.pair.left = a;
		n->params.pair.right = b;
	}
	return n;
}


#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_alternate(struct rx *rx,
											struct rexp_node *a,
											struct rexp_node *b)
#else
RX_DECL struct rexp_node *rx_mk_r_alternate(rx, a, b)
struct rx *rx;
struct rexp_node *a;
struct rexp_node *b;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_alternate);

	if (n) {
		n->params.pair.left = a;
		n->params.pair.right = b;
	}
	return n;
}


#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_opt(struct rx *rx, struct rexp_node *a)
#else
RX_DECL struct rexp_node *rx_mk_r_opt(rx, a)
struct rx *rx;
struct rexp_node *a;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_opt);

	if (n) {
		n->params.pair.left = a;
		n->params.pair.right = 0;
	}
	return n;
}

#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_star(struct rx *rx, struct rexp_node *a)
#else
RX_DECL struct rexp_node *rx_mk_r_star(rx, a)
struct rx *rx;
struct rexp_node *a;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_star);

	if (n) {
		n->params.pair.left = a;
		n->params.pair.right = 0;
	}
	return n;
}


#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_2phase_star(struct rx *rx,
											  struct rexp_node *a,
											  struct rexp_node *b)
#else
RX_DECL struct rexp_node *rx_mk_r_2phase_star(rx, a, b)
struct rx *rx;
struct rexp_node *a;
struct rexp_node *b;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_2phase_star);

	if (n) {
		n->params.pair.left = a;
		n->params.pair.right = b;
	}
	return n;
}

#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_side_effect(struct rx *rx,
											  rx_side_effect a)
#else
RX_DECL struct rexp_node *rx_mk_r_side_effect(rx, a)
struct rx *rx;
rx_side_effect a;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_side_effect);

	if (n) {
		n->params.side_effect = a;
		n->params.pair.right = 0;
	}
	return n;
}


#if 0
#ifdef __STDC__
RX_DECL struct rexp_node *rx_mk_r_data(struct rx *rx, void *a)
#else
RX_DECL struct rexp_node *rx_mk_r_data(rx, a)
struct rx *rx;
void *a;
#endif
{
	struct rexp_node *n = rexp_node(rx, r_data);

	if (n) {
		n->params.pair.left = a;
		n->params.pair.right = 0;
	}
	return n;
}
#endif

#ifdef __STDC__
RX_DECL void rx_free_rexp(struct rx *rx, struct rexp_node *node)
#else
RX_DECL void rx_free_rexp(rx, node)
struct rx *rx;
struct rexp_node *node;
#endif
{
	if (node) {
		switch (node->type) {
		case r_cset:
			if (node->params.cset)
				rx_free_cset(rx, node->params.cset);

		case r_side_effect:
			break;

		case r_concat:
		case r_alternate:
		case r_2phase_star:
		case r_opt:
		case r_star:
			rx_free_rexp(rx, node->params.pair.left);
			rx_free_rexp(rx, node->params.pair.right);
			break;

		case r_data:
			/* This shouldn't occur. */
			break;
		}
		free((char *) node);
	}
}

#ifdef __STDC__
RX_DECL struct rexp_node *rx_copy_rexp(struct rx *rx,
									   struct rexp_node *node)
#else
RX_DECL struct rexp_node *rx_copy_rexp(rx, node)
struct rx *rx;
struct rexp_node *node;
#endif
{
	if (!node)
		return 0;
	else {
		struct rexp_node *n = rexp_node(rx, node->type);

		if (!n)
			return 0;
		switch (node->type) {
		case r_cset:
			n->params.cset = rx_copy_cset(rx, node->params.cset);
			if (!n->params.cset) {
				rx_free_rexp(rx, n);
				return 0;
			}
			break;

		case r_side_effect:
			n->params.side_effect = node->params.side_effect;
			break;

		case r_concat:
		case r_alternate:
		case r_opt:
		case r_2phase_star:
		case r_star:
			n->params.pair.left = rx_copy_rexp(rx, node->params.pair.left);
			n->params.pair.right =
				rx_copy_rexp(rx, node->params.pair.right);
			if ((node->params.pair.left && !n->params.pair.left)
				|| (node->params.pair.right && !n->params.pair.right)) {
				rx_free_rexp(rx, n);
				return 0;
			}
			break;
		case r_data:
			/* shouldn't happen */
			break;
		}
		return n;
	}
}



/* This page: functions to build and destroy graphs that describe nfa's */

/* Constructs a new nfa node. */
#ifdef __STDC__
RX_DECL struct rx_nfa_state *rx_nfa_state(struct rx *rx)
#else
RX_DECL struct rx_nfa_state *rx_nfa_state(rx)
struct rx *rx;
#endif
{
	struct rx_nfa_state *n = (struct rx_nfa_state *) malloc(sizeof(*n));

	if (!n)
		return 0;
	bzero(n, sizeof(*n));
	n->next = rx->nfa_states;
	rx->nfa_states = n;
	return n;
}


#ifdef __STDC__
RX_DECL void rx_free_nfa_state(struct rx_nfa_state *n)
#else
RX_DECL void rx_free_nfa_state(n)
struct rx_nfa_state *n;
#endif
{
	free((char *) n);
}


/* This looks up an nfa node, given a numeric id.  Numeric id's are
 * assigned after the nfa has been built.
 */
#ifdef __STDC__
RX_DECL struct rx_nfa_state *rx_id_to_nfa_state(struct rx *rx, int id)
#else
RX_DECL struct rx_nfa_state *rx_id_to_nfa_state(rx, id)
struct rx *rx;
int id;
#endif
{
	struct rx_nfa_state *n;

	for (n = rx->nfa_states; n; n = n->next)
		if (n->id == id)
			return n;
	return 0;
}


/* This adds an edge between two nodes, but doesn't initialize the 
 * edge label.
 */

#ifdef __STDC__
RX_DECL struct rx_nfa_edge *rx_nfa_edge(struct rx *rx,
										enum rx_nfa_etype type,
										struct rx_nfa_state *start,
										struct rx_nfa_state *dest)
#else
RX_DECL struct rx_nfa_edge *rx_nfa_edge(rx, type, start, dest)
struct rx *rx;
enum rx_nfa_etype type;
struct rx_nfa_state *start;
struct rx_nfa_state *dest;
#endif
{
	struct rx_nfa_edge *e;

	e = (struct rx_nfa_edge *) malloc(sizeof(*e));
	if (!e)
		return 0;
	e->next = start->edges;
	start->edges = e;
	e->type = type;
	e->dest = dest;
	return e;
}


#ifdef __STDC__
RX_DECL void rx_free_nfa_edge(struct rx_nfa_edge *e)
#else
RX_DECL void rx_free_nfa_edge(e)
struct rx_nfa_edge *e;
#endif
{
	free((char *) e);
}


/* This constructs a POSSIBLE_FUTURE, which is a kind epsilon-closure
 * of an NFA.  These are added to an nfa automaticly by eclose_nfa.
 */

#ifdef __STDC__
static struct rx_possible_future *rx_possible_future(struct rx *rx, struct rx_se_list
													 *effects)
#else
static struct rx_possible_future *rx_possible_future(rx, effects)
struct rx *rx;
struct rx_se_list *effects;
#endif
{
	struct rx_possible_future *ec;

	ec = (struct rx_possible_future *) malloc(sizeof(*ec));
	if (!ec)
		return 0;
	ec->destset = 0;
	ec->next = 0;
	ec->effects = effects;
	return ec;
}


#ifdef __STDC__
static void rx_free_possible_future(struct rx_possible_future *pf)
#else
static void rx_free_possible_future(pf)
struct rx_possible_future *pf;
#endif
{
	free((char *) pf);
}


#ifdef __STDC__
RX_DECL void rx_free_nfa(struct rx *rx)
#else
RX_DECL void rx_free_nfa(rx)
struct rx *rx;
#endif
{
	while (rx->nfa_states) {
		while (rx->nfa_states->edges) {
			switch (rx->nfa_states->edges->type) {
			case ne_cset:
				rx_free_cset(rx, rx->nfa_states->edges->params.cset);
				break;
			default:
				break;
			}
			{
				struct rx_nfa_edge *e;

				e = rx->nfa_states->edges;
				rx->nfa_states->edges = rx->nfa_states->edges->next;
				rx_free_nfa_edge(e);
			}
		}						/* while (rx->nfa_states->edges) */
		{
			/* Iterate over the partial epsilon closures of rx->nfa_states */
			struct rx_possible_future *pf = rx->nfa_states->futures;

			while (pf) {
				struct rx_possible_future *pft = pf;

				pf = pf->next;
				rx_free_possible_future(pft);
			}
		}
		{
			struct rx_nfa_state *n;

			n = rx->nfa_states;
			rx->nfa_states = rx->nfa_states->next;
			rx_free_nfa_state(n);
		}
	}
}



/* This page: translating a pattern expression into an nfa and doing the 
 * static part of the nfa->super-nfa translation.
 */

/* This is the thompson regexp->nfa algorithm. 
 * It is modified to allow for `side-effect epsilons.'  Those are
 * edges that are taken whenever a similar epsilon edge would be,
 * but which imply that some side effect occurs when the edge 
 * is taken.
 *
 * Side effects are used to model parts of the pattern langauge 
 * that are not regular (in the formal sense).
 */

#ifdef __STDC__
RX_DECL int
rx_build_nfa(struct rx *rx,
			 struct rexp_node *rexp,
			 struct rx_nfa_state **start, struct rx_nfa_state **end)
#else
RX_DECL int rx_build_nfa(rx, rexp, start, end)
struct rx *rx;
struct rexp_node *rexp;
struct rx_nfa_state **start;
struct rx_nfa_state **end;
#endif
{
	struct rx_nfa_edge *edge;

	/* Start & end nodes may have been allocated by the caller. */
	*start = *start ? *start : rx_nfa_state(rx);

	if (!*start)
		return 0;

	if (!rexp) {
		*end = *start;
		return 1;
	}

	*end = *end ? *end : rx_nfa_state(rx);

	if (!*end) {
		rx_free_nfa_state(*start);
		return 0;
	}

	switch (rexp->type) {
	case r_data:
		return 0;

	case r_cset:
		edge = rx_nfa_edge(rx, ne_cset, *start, *end);
		if (!edge)
			return 0;
		edge->params.cset = rx_copy_cset(rx, rexp->params.cset);
		if (!edge->params.cset) {
			rx_free_nfa_edge(edge);
			return 0;
		}
		return 1;

	case r_opt:
		return (rx_build_nfa(rx, rexp->params.pair.left, start, end)
				&& rx_nfa_edge(rx, ne_epsilon, *start, *end));

	case r_star:
	{
		struct rx_nfa_state *star_start = 0;
		struct rx_nfa_state *star_end = 0;

		return (rx_build_nfa(rx, rexp->params.pair.left,
							 &star_start, &star_end)
				&& star_start
				&& star_end
				&& rx_nfa_edge(rx, ne_epsilon, star_start, star_end)
				&& rx_nfa_edge(rx, ne_epsilon, *start, star_start)
				&& rx_nfa_edge(rx, ne_epsilon, star_end, *end)

				&& rx_nfa_edge(rx, ne_epsilon, star_end, star_start));
	}

	case r_2phase_star:
	{
		struct rx_nfa_state *star_start = 0;
		struct rx_nfa_state *star_end = 0;
		struct rx_nfa_state *loop_exp_start = 0;
		struct rx_nfa_state *loop_exp_end = 0;

		return (rx_build_nfa(rx, rexp->params.pair.left,
							 &star_start, &star_end)
				&& rx_build_nfa(rx, rexp->params.pair.right,
								&loop_exp_start, &loop_exp_end)
				&& star_start
				&& star_end
				&& loop_exp_end
				&& loop_exp_start
				&& rx_nfa_edge(rx, ne_epsilon, star_start, *end)
				&& rx_nfa_edge(rx, ne_epsilon, *start, star_start)
				&& rx_nfa_edge(rx, ne_epsilon, star_end, *end)

				&& rx_nfa_edge(rx, ne_epsilon, star_end, loop_exp_start)
				&& rx_nfa_edge(rx, ne_epsilon, loop_exp_end, star_start));
	}


	case r_concat:
	{
		struct rx_nfa_state *shared = 0;

		return (rx_build_nfa(rx, rexp->params.pair.left, start, &shared)
				&& rx_build_nfa(rx, rexp->params.pair.right, &shared,
								end));
	}

	case r_alternate:
	{
		struct rx_nfa_state *ls = 0;
		struct rx_nfa_state *le = 0;
		struct rx_nfa_state *rs = 0;
		struct rx_nfa_state *re = 0;

		return (rx_build_nfa(rx, rexp->params.pair.left, &ls, &le)
				&& rx_build_nfa(rx, rexp->params.pair.right, &rs, &re)
				&& rx_nfa_edge(rx, ne_epsilon, *start, ls)
				&& rx_nfa_edge(rx, ne_epsilon, *start, rs)
				&& rx_nfa_edge(rx, ne_epsilon, le, *end)
				&& rx_nfa_edge(rx, ne_epsilon, re, *end));
	}

	case r_side_effect:
		edge = rx_nfa_edge(rx, ne_side_effect, *start, *end);
		if (!edge)
			return 0;
		edge->params.side_effect = rexp->params.side_effect;
		return 1;
	}

	/* this should never happen */
	return 0;
}


/* RX_NAME_NFA_STATES identifies all nodes with outgoing non-epsilon
 * transitions.  Only these nodes can occur in super-states.  
 * All nodes are given an integer id. 
 * The id is non-negative if the node has non-epsilon out-transitions, negative
 * otherwise (this is because we want the non-negative ids to be used as 
 * array indexes in a few places).
 */

#ifdef __STDC__
RX_DECL void rx_name_nfa_states(struct rx *rx)
#else
RX_DECL void rx_name_nfa_states(rx)
struct rx *rx;
#endif
{
	struct rx_nfa_state *n = rx->nfa_states;

	rx->nodec = 0;
	rx->epsnodec = -1;

	while (n) {
		struct rx_nfa_edge *e = n->edges;

		if (n->is_start)
			n->eclosure_needed = 1;

		while (e) {
			switch (e->type) {
			case ne_epsilon:
			case ne_side_effect:
				break;

			case ne_cset:
				n->id = rx->nodec++;
				{
					struct rx_nfa_edge *from_n = n->edges;

					while (from_n) {
						from_n->dest->eclosure_needed = 1;
						from_n = from_n->next;
					}
				}
				goto cont;
			}
			e = e->next;
		}
		n->id = rx->epsnodec--;
	  cont:
		n = n->next;
	}
	rx->epsnodec = -rx->epsnodec;
}


/* This page: data structures for the static part of the nfa->supernfa
 * translation.
 *
 * There are side effect lists -- lists of side effects occuring
 * along an uninterrupted, acyclic path of side-effect epsilon edges.
 * Such paths are collapsed to single edges in the course of computing
 * epsilon closures.  Such single edges are labled with a list of all
 * the side effects entailed in crossing them.  Like lists of side
 * effects are made == by the constructors below.
 *
 * There are also nfa state sets.  These are used to hold a list of all
 * states reachable from a starting state for a given type of transition
 * and side effect list.   These are also hash-consed.
 */

/* The next several functions compare, construct, etc. lists of side
 * effects.  See ECLOSE_NFA (below) for details.
 */

/* Ordering of rx_se_list
 * (-1, 0, 1 return value convention).
 */

#ifdef __STDC__
static int se_list_cmp(void *va, void *vb)
#else
static int se_list_cmp(va, vb)
void *va;
void *vb;
#endif
{
	struct rx_se_list *a = (struct rx_se_list *) va;
	struct rx_se_list *b = (struct rx_se_list *) vb;

	return ((va == vb)
			? 0
			: (!va
			   ? -1
			   : (!vb
				  ? 1
				  : ((long) a->car < (long) b->car
					 ? 1
					 : ((long) a->car > (long) b->car
						? -1
						: se_list_cmp((void *) a->cdr,
									  (void *) b->cdr))))));
}


#ifdef __STDC__
static int se_list_equal(void *va, void *vb)
#else
static int se_list_equal(va, vb)
void *va;
void *vb;
#endif
{
	return !(se_list_cmp(va, vb));
}

static struct rx_hash_rules se_list_hash_rules = {
	se_list_equal,
	compiler_hash_alloc,
	compiler_free_hash,
	compiler_hash_item_alloc,
	compiler_free_hash_item
};


#ifdef __STDC__
static struct rx_se_list *side_effect_cons(struct rx *rx,
										   void *se,
										   struct rx_se_list *list)
#else
static struct rx_se_list *side_effect_cons(rx, se, list)
struct rx *rx;
void *se;
struct rx_se_list *list;
#endif
{
	struct rx_se_list *l;

	l = ((struct rx_se_list *) malloc(sizeof(*l)));
	if (!l)
		return 0;
	l->car = se;
	l->cdr = list;
	return l;
}


#ifdef __STDC__
static struct rx_se_list *hash_cons_se_prog(struct rx *rx,
											struct rx_hash *memo,
											void *car,
											struct rx_se_list *cdr)
#else
static struct rx_se_list *hash_cons_se_prog(rx, memo, car, cdr)
struct rx *rx;
struct rx_hash *memo;
void *car;
struct rx_se_list *cdr;
#endif
{
	long hash = (long) car ^ (long) cdr;
	struct rx_se_list template;

	template.car = car;
	template.cdr = cdr;
	{
		struct rx_hash_item *it = rx_hash_store(memo, hash,
												(void *) &template,
												&se_list_hash_rules);

		if (!it)
			return 0;
		if (it->data == (void *) &template) {
			struct rx_se_list *consed;

			consed = (struct rx_se_list *) malloc(sizeof(*consed));
			if (!consed) {
				free((char *) it);
				return 0;
			}
			*consed = template;
			it->data = (void *) consed;
		}
		return (struct rx_se_list *) it->data;
	}
}


#ifdef __STDC__
static struct rx_se_list *hash_se_prog(struct rx *rx, struct rx_hash *memo,
									   struct rx_se_list *prog)
#else
static struct rx_se_list *hash_se_prog(rx, memo, prog)
struct rx *rx;
struct rx_hash *memo;
struct rx_se_list *prog;
#endif
{
	struct rx_se_list *answer = 0;

	while (prog) {
		answer = hash_cons_se_prog(rx, memo, prog->car, answer);
		if (!answer)
			return 0;
		prog = prog->cdr;
	}
	return answer;
}

#ifdef __STDC__
static int nfa_set_cmp(void *va, void *vb)
#else
static int nfa_set_cmp(va, vb)
void *va;
void *vb;
#endif
{
	struct rx_nfa_state_set *a = (struct rx_nfa_state_set *) va;
	struct rx_nfa_state_set *b = (struct rx_nfa_state_set *) vb;

	return ((va == vb)
			? 0
			: (!va
			   ? -1
			   : (!vb
				  ? 1
				  : (a->car->id < b->car->id
					 ? 1
					 : (a->car->id > b->car->id
						? -1
						: nfa_set_cmp((void *) a->cdr,
									  (void *) b->cdr))))));
}

#ifdef __STDC__
static int nfa_set_equal(void *va, void *vb)
#else
static int nfa_set_equal(va, vb)
void *va;
void *vb;
#endif
{
	return !nfa_set_cmp(va, vb);
}

static struct rx_hash_rules nfa_set_hash_rules = {
	nfa_set_equal,
	compiler_hash_alloc,
	compiler_free_hash,
	compiler_hash_item_alloc,
	compiler_free_hash_item
};


#ifdef __STDC__
static struct rx_nfa_state_set *nfa_set_cons(struct rx *rx,
											 struct rx_hash *memo,
											 struct rx_nfa_state *state,
											 struct rx_nfa_state_set *set)
#else
static struct rx_nfa_state_set *nfa_set_cons(rx, memo, state, set)
struct rx *rx;
struct rx_hash *memo;
struct rx_nfa_state *state;
struct rx_nfa_state_set *set;
#endif
{
	struct rx_nfa_state_set template;
	struct rx_hash_item *node;

	template.car = state;
	template.cdr = set;
	node = rx_hash_store(memo,
						 (((long) state) >> 8) ^ (long) set,
						 &template, &nfa_set_hash_rules);
	if (!node)
		return 0;
	if (node->data == &template) {
		struct rx_nfa_state_set *l;

		l = (struct rx_nfa_state_set *) malloc(sizeof(*l));
		node->data = (void *) l;
		if (!l)
			return 0;
		*l = template;
	}
	return (struct rx_nfa_state_set *) node->data;
}

#ifdef __STDC__
static struct rx_nfa_state_set *nfa_set_enjoin(struct rx *rx,
											   struct rx_hash *memo,
											   struct rx_nfa_state *state,
											   struct rx_nfa_state_set
											   *set)
#else
static struct rx_nfa_state_set *nfa_set_enjoin(rx, memo, state, set)
struct rx *rx;
struct rx_hash *memo;
struct rx_nfa_state *state;
struct rx_nfa_state_set *set;
#endif
{
	if (!set || state->id < set->car->id)
		return nfa_set_cons(rx, memo, state, set);
	if (state->id == set->car->id)
		return set;
	else {
		struct rx_nfa_state_set *newcdr

			= nfa_set_enjoin(rx, memo, state, set->cdr);
		if (newcdr != set->cdr)
			set = nfa_set_cons(rx, memo, set->car, newcdr);
		return set;
	}
}



/* This page: computing epsilon closures.  The closures aren't total.
 * Each node's closures are partitioned according to the side effects entailed
 * along the epsilon edges.  Return true on success.
 */

struct eclose_frame {
	struct rx_se_list *prog_backwards;
};
static int eclose_node(struct rx *, struct rx_nfa_state *,
					   struct rx_nfa_state *, struct eclose_frame *);
RX_DECL int rx_eclose_nfa(struct rx *);
RX_DECL void rx_delete_epsilon_transitions(struct rx *);
static int nfacmp(void *, void *);
static int count_hash_nodes(struct rx_hash *);
static void nfa_set_freer(struct rx_hash_item *);
RX_DECL int rx_compactify_nfa(struct rx *, void **, unsigned long *);
static char *rx_cache_malloc(struct rx_cache *, int);
static void rx_cache_free(struct rx_cache *,

						  struct rx_freelist **, char *);
static void install_transition(struct rx_superstate *,

							   struct rx_inx *, rx_Bitset);
static int qlen(struct rx_superstate *);
static void check_cache(struct rx_cache *);
static void semifree_superstate(struct rx_cache *);
static void refresh_semifree_superstate

	(struct rx_cache *, struct rx_superstate *);
static void rx_refresh_this_superstate

	(struct rx_cache *, struct rx_superstate *);
static void release_superset_low(struct rx_cache *, struct rx_superset *);
RX_DECL void rx_release_superset(struct rx *, struct rx_superset *);
static int rx_really_free_superstate(struct rx_cache *);
static char *rx_cache_get(struct rx_cache *, struct rx_freelist **);
static char *rx_cache_malloc_or_get(struct rx_cache *,
									struct rx_freelist **, int);
static char *rx_cache_get_superstate(struct rx_cache *);
static int supersetcmp(void *, void *);
static struct rx_hash_item
*superset_allocator(struct rx_hash_rules *, void *);
static struct rx_hash
*super_hash_allocator(struct rx_hash_rules *);
static void super_hash_liberator(struct rx_hash *, struct rx_hash_rules *);
static void superset_hash_item_liberator

	(struct rx_hash_item *, struct rx_hash_rules *);
static int bytes_for_cache_size(int, int);
static void rx_morecore(struct rx_cache *);
RX_DECL struct rx_superset
*rx_superset_cons(struct rx *, struct rx_nfa_state *,

				  struct rx_superset *);
RX_DECL struct rx_superset
*rx_superstate_eclosure_union

	(struct rx *, struct rx_superset *, struct rx_nfa_state_set *);
static struct rx_distinct_future
*include_futures(struct rx *,
				 struct rx_distinct_future *,

				 struct rx_nfa_state *, struct rx_superstate *);
RX_DECL struct rx_superstate
*rx_superstate(struct rx *, struct rx_superset *);
static int solve_destination(struct rx *, struct rx_distinct_future *);
static int compute_super_edge(struct rx *,
							  struct rx_distinct_future **,

							  rx_Bitset, struct rx_superstate *,
							  unsigned char);
static struct rx_super_edge
*rx_super_edge(struct rx *, struct rx_superstate *,

			   rx_Bitset, struct rx_distinct_future *);
static void install_partial_transition
	(struct rx_superstate *, struct rx_inx *, RX_subset, int);
RX_DECL struct rx_inx
*rx_handle_cache_miss(struct rx *, struct rx_superstate *,

					  unsigned char, void *);
static boolean

at_begline_loc_p(__const__ char *, __const__ char *, reg_syntax_t);
static boolean at_endline_loc_p(__const__ char *, __const__ char *, int);
static rx_Bitset
inverse_translation(struct re_pattern_buffer *, char *,
					rx_Bitset, unsigned char *, int);


#ifdef __STDC__
static int
eclose_node(struct rx *rx, struct rx_nfa_state *outnode,
			struct rx_nfa_state *node, struct eclose_frame *frame)
#else
static int eclose_node(rx, outnode, node, frame)
struct rx *rx;
struct rx_nfa_state *outnode;
struct rx_nfa_state *node;
struct eclose_frame *frame;
#endif
{
	struct rx_nfa_edge *e = node->edges;

	/* For each node, we follow all epsilon paths to build the closure.
	 * The closure omits nodes that have only epsilon edges.
	 * The closure is split into partial closures -- all the states in
	 * a partial closure are reached by crossing the same list of
	 * of side effects (though not necessarily the same path).
	 */
	if (node->mark)
		return 1;
	node->mark = 1;

	if (node->id >= 0 || node->is_final) {
		struct rx_possible_future **ec;
		struct rx_se_list *prog_in_order
			= ((struct rx_se_list *) hash_se_prog(rx,
												  &rx->se_list_memo,
												  frame->prog_backwards));
		int cmp;

		ec = &outnode->futures;

		while (*ec) {
			cmp =
				se_list_cmp((void *) (*ec)->effects,
							(void *) prog_in_order);
			if (cmp <= 0)
				break;
			ec = &(*ec)->next;
		}
		if (!*ec || (cmp < 0)) {
			struct rx_possible_future *saved = *ec;

			*ec = rx_possible_future(rx, prog_in_order);
			(*ec)->next = saved;
			if (!*ec)
				return 0;
		}
		if (node->id >= 0) {
			(*ec)->destset = nfa_set_enjoin(rx, &rx->set_list_memo,
											node, (*ec)->destset);
			if (!(*ec)->destset)
				return 0;
		}
	}

	while (e) {
		switch (e->type) {
		case ne_epsilon:
			if (!eclose_node(rx, outnode, e->dest, frame))
				return 0;
			break;
		case ne_side_effect:
		{
			frame->prog_backwards = side_effect_cons(rx,
													 e->params.side_effect,
													 frame->prog_backwards);
			if (!frame->prog_backwards)
				return 0;
			if (!eclose_node(rx, outnode, e->dest, frame))
				return 0;
			{
				struct rx_se_list *dying = frame->prog_backwards;

				frame->prog_backwards = frame->prog_backwards->cdr;
				free((char *) dying);
			}
			break;
		}
		default:
			break;
		}
		e = e->next;
	}
	node->mark = 0;
	return 1;
}

#ifdef __STDC__
RX_DECL int rx_eclose_nfa(struct rx *rx)
#else
RX_DECL int rx_eclose_nfa(rx)
struct rx *rx;
#endif
{
	struct rx_nfa_state *n = rx->nfa_states;
	struct eclose_frame frame;
	static int rx_id = 0;

	frame.prog_backwards = 0;
	rx->rx_id = rx_id++;
	bzero(&rx->se_list_memo, sizeof(rx->se_list_memo));
	bzero(&rx->set_list_memo, sizeof(rx->set_list_memo));
	while (n) {
		n->futures = 0;
		if (n->eclosure_needed && !eclose_node(rx, n, n, &frame))
			return 0;
		/* clear_marks (rx); */
		n = n->next;
	}
	return 1;
}


/* This deletes epsilon edges from an NFA.  After running eclose_node,
 * we have no more need for these edges.  They are removed to simplify
 * further operations on the NFA.
 */

#ifdef __STDC__
RX_DECL void rx_delete_epsilon_transitions(struct rx *rx)
#else
RX_DECL void rx_delete_epsilon_transitions(rx)
struct rx *rx;
#endif
{
	struct rx_nfa_state *n = rx->nfa_states;
	struct rx_nfa_edge **e;

	while (n) {
		e = &n->edges;
		while (*e) {
			struct rx_nfa_edge *t;

			switch ((*e)->type) {
			case ne_epsilon:
			case ne_side_effect:
				t = *e;
				*e = t->next;
				rx_free_nfa_edge(t);
				break;

			default:
				e = &(*e)->next;
				break;
			}
		}
		n = n->next;
	}
}


/* This page: storing the nfa in a contiguous region of memory for
 * subsequent conversion to a super-nfa.
 */

/* This is for qsort on an array of nfa_states. The order
 * is based on state ids and goes 
 *		[0...MAX][MIN..-1] where (MAX>=0) and (MIN<0)
 * This way, positive ids double as array indices.
 */

#ifdef __STDC__
static int nfacmp(void *va, void *vb)
#else
static int nfacmp(va, vb)
void *va;
void *vb;
#endif
{
	struct rx_nfa_state **a = (struct rx_nfa_state **) va;
	struct rx_nfa_state **b = (struct rx_nfa_state **) vb;

	return (*a == *b			/* &&&& 3.18 */
			? 0 : (((*a)->id < 0) == ((*b)->id < 0)
				   ? (((*a)->id < (*b)->id) ? -1 : 1)
				   : (((*a)->id < 0)
					  ? 1 : -1)));
}

#ifdef __STDC__
static int count_hash_nodes(struct rx_hash *st)
#else
static int count_hash_nodes(st)
struct rx_hash *st;
#endif
{
	int x;
	int count = 0;

	for (x = 0; x < 13; ++x)
		count += ((st->children[x])
				  ? count_hash_nodes(st->children[x])
				  : st->bucket_size[x]);

	return count;
}


#ifdef __STDC__
static void se_memo_freer(struct rx_hash_item *node)
#else
static void se_memo_freer(node)
struct rx_hash_item *node;
#endif
{
	free((char *) node->data);
}


#ifdef __STDC__
static void nfa_set_freer(struct rx_hash_item *node)
#else
static void nfa_set_freer(node)
struct rx_hash_item *node;
#endif
{
	free((char *) node->data);
}


/* This copies an entire NFA into a single malloced block of memory.
 * Mostly this is for compatability with regex.c, though it is convenient
 * to have the nfa nodes in an array.
 */

#ifdef __STDC__
RX_DECL int
rx_compactify_nfa(struct rx *rx, void **mem, unsigned long *size)
#else
RX_DECL int rx_compactify_nfa(rx, mem, size)
struct rx *rx;
void **mem;
unsigned long *size;
#endif
{
	int total_nodec;
	struct rx_nfa_state *n;
	int edgec = 0;
	int eclosec = 0;
	int se_list_consc = count_hash_nodes(&rx->se_list_memo);
	int nfa_setc = count_hash_nodes(&rx->set_list_memo);
	unsigned long total_size;

	/* This takes place in two stages.   First, the total size of the
	 * nfa is computed, then structures are copied.  
	 */
	n = rx->nfa_states;
	total_nodec = 0;
	while (n) {
		struct rx_nfa_edge *e = n->edges;
		struct rx_possible_future *ec = n->futures;

		++total_nodec;
		while (e) {
			++edgec;
			e = e->next;
		}
		while (ec) {
			++eclosec;
			ec = ec->next;
		}
		n = n->next;
	}

	total_size = (total_nodec * sizeof(struct rx_nfa_state)
				  + edgec * rx_sizeof_bitset(rx->local_cset_size)
				  + edgec * sizeof(struct rx_nfa_edge)
				  + nfa_setc * sizeof(struct rx_nfa_state_set)
				  + eclosec * sizeof(struct rx_possible_future)
				  + se_list_consc * sizeof(struct rx_se_list)
				  + rx->reserved);

	if (total_size > *size) {
		*mem = remalloc(*mem, total_size);
		if (*mem)
			*size = total_size;
		else
			return 0;
	}
	/* Now we've allocated the memory; this copies the NFA. */
	{
		static struct rx_nfa_state **scratch = 0;
		static int scratch_alloc = 0;
		struct rx_nfa_state *state_base = (struct rx_nfa_state *) *mem;
		struct rx_nfa_state *new_state = state_base;
		struct rx_nfa_edge *new_edge = (struct rx_nfa_edge *)
			((char *) state_base + total_nodec * sizeof(struct rx_nfa_state));
		struct rx_se_list *new_se_list = (struct rx_se_list *)
			((char *) new_edge + edgec * sizeof(struct rx_nfa_edge));
		struct rx_possible_future *new_close =
			((struct rx_possible_future *)
			 ((char *) new_se_list

			  + se_list_consc * sizeof(struct rx_se_list)));
		struct rx_nfa_state_set *new_nfa_set = ((struct rx_nfa_state_set *)

												((char *) new_close +
												 eclosec *

												 sizeof(struct
														rx_possible_future)));
		char *new_bitset =

			((char *) new_nfa_set +
			 nfa_setc * sizeof(struct rx_nfa_state_set));
		int x;
		struct rx_nfa_state *n;

		if (scratch_alloc < total_nodec) {
			scratch = ((struct rx_nfa_state **)
					   remalloc(scratch, total_nodec * sizeof(*scratch)));
			if (scratch)
				scratch_alloc = total_nodec;
			else {
				scratch_alloc = 0;
				return 0;
			}
		}

		for (x = 0, n = rx->nfa_states; n; n = n->next)
			scratch[x++] = n;

		qsort(scratch, total_nodec, sizeof(struct rx_nfa_state *),
			  (__compar_fn_t) nfacmp);

		for (x = 0; x < total_nodec; ++x) {
			struct rx_possible_future *eclose = scratch[x]->futures;
			struct rx_nfa_edge *edge = scratch[x]->edges;
			struct rx_nfa_state *cn = new_state++;

			cn->futures = 0;
			cn->edges = 0;
			cn->next = (x == total_nodec - 1) ? 0 : (cn + 1);
			cn->id = scratch[x]->id;
			cn->is_final = scratch[x]->is_final;
			cn->is_start = scratch[x]->is_start;
			cn->mark = 0;
			while (edge) {
				int indx = (edge->dest->id < 0
							? (total_nodec + edge->dest->id)

							: edge->dest->id);
				struct rx_nfa_edge *e = new_edge++;
				rx_Bitset cset = (rx_Bitset) new_bitset;

				new_bitset += rx_sizeof_bitset(rx->local_cset_size);
				rx_bitset_null(rx->local_cset_size, cset);
				rx_bitset_union(rx->local_cset_size, cset,
								edge->params.cset);
				e->next = cn->edges;
				cn->edges = e;
				e->type = edge->type;
				e->dest = state_base + indx;
				e->params.cset = cset;
				edge = edge->next;
			}
			while (eclose) {
				struct rx_possible_future *ec = new_close++;
				struct rx_hash_item *sp;
				struct rx_se_list **sepos;
				struct rx_se_list *sesrc;
				struct rx_nfa_state_set *destlst;
				struct rx_nfa_state_set **destpos;

				ec->next = cn->futures;
				cn->futures = ec;
				for (sepos = &ec->effects, sesrc = eclose->effects;
					 sesrc; sesrc = sesrc->cdr, sepos = &(*sepos)->cdr) {
					sp = rx_hash_find(&rx->se_list_memo,
									  (long) sesrc->
									  car ^ (long) sesrc->cdr, sesrc,
									  &se_list_hash_rules);
					if (sp->binding) {
						sesrc = (struct rx_se_list *) sp->binding;
						break;
					}
					*new_se_list = *sesrc;
					sp->binding = (void *) new_se_list;
					*sepos = new_se_list;
					++new_se_list;
				}
				*sepos = sesrc;
				for (destpos = &ec->destset, destlst = eclose->destset;
					 destlst;
					 destpos = &(*destpos)->cdr, destlst = destlst->cdr) {
					sp = rx_hash_find(&rx->set_list_memo,
									  ((((long) destlst->car) >> 8)
									   ^ (long) destlst->cdr),
									  destlst, &nfa_set_hash_rules);
					if (sp->binding) {
						destlst = (struct rx_nfa_state_set *) sp->binding;
						break;
					}
					*new_nfa_set = *destlst;
					new_nfa_set->car = state_base + destlst->car->id;
					sp->binding = (void *) new_nfa_set;
					*destpos = new_nfa_set;
					++new_nfa_set;
				}
				*destpos = destlst;
				eclose = eclose->next;
			}
		}
	}
	rx_free_hash_table(&rx->se_list_memo, se_memo_freer,
					   &se_list_hash_rules);
	bzero(&rx->se_list_memo, sizeof(rx->se_list_memo));
	rx_free_hash_table(&rx->set_list_memo, nfa_set_freer,
					   &nfa_set_hash_rules);
	bzero(&rx->set_list_memo, sizeof(rx->set_list_memo));

	rx_free_nfa(rx);
	rx->nfa_states = (struct rx_nfa_state *) *mem;
	return 1;
}


/* The functions in the next several pages define the lazy-NFA-conversion used
 * by matchers.  The input to this construction is an NFA such as 
 * is built by compactify_nfa (rx.c).  The output is the superNFA.
 */

/* Match engines can use arbitrary values for opcodes.  So, the parse tree 
 * is built using instructions names (enum rx_opcode), but the superstate
 * nfa is populated with mystery opcodes (void *).
 *
 * For convenience, here is an id table.  The opcodes are == to their inxs
 *
 * The lables in re_search_2 would make good values for instructions.
 */

void *rx_id_instruction_table[rx_num_instructions] = {
	(void *) rx_backtrack_point,
	(void *) rx_do_side_effects,
	(void *) rx_cache_miss,
	(void *) rx_next_char,
	(void *) rx_backtrack,
	(void *) rx_error_inx
};



/* Memory mgt. for superstate graphs. */

#ifdef __STDC__
static char *rx_cache_malloc(struct rx_cache *cache, int bytes)
#else
static char *rx_cache_malloc(cache, bytes)
struct rx_cache *cache;
int bytes;
#endif
{
	while (cache->bytes_left < bytes) {
		if (cache->memory_pos)
			cache->memory_pos = cache->memory_pos->next;
		if (!cache->memory_pos) {
			cache->morecore(cache);
			if (!cache->memory_pos)
				return 0;
		}
		cache->bytes_left = cache->memory_pos->bytes;
		cache->memory_addr = ((char *) cache->memory_pos

							  + sizeof(struct rx_blocklist));
	}
	cache->bytes_left -= bytes;
	{
		char *addr = cache->memory_addr;

		cache->memory_addr += bytes;
		return addr;
	}
}

#ifdef __STDC__
static void
rx_cache_free(struct rx_cache *cache,
			  struct rx_freelist **freelist, char *mem)
#else
static void rx_cache_free(cache, freelist, mem)
struct rx_cache *cache;
struct rx_freelist **freelist;
char *mem;
#endif
{
	struct rx_freelist *it = (struct rx_freelist *) mem;

	it->next = *freelist;
	*freelist = it;
}

/* The partially instantiated superstate graph has a transition 
 * table at every node.  There is one entry for every character.
 * This fills in the transition for a set.
 */
#ifdef __STDC__
static void
install_transition(struct rx_superstate *super,
				   struct rx_inx *answer, rx_Bitset trcset)
#else
static void install_transition(super, answer, trcset)
struct rx_superstate *super;
struct rx_inx *answer;
rx_Bitset trcset;
#endif
{
	struct rx_inx *transitions = super->transitions;
	int chr;

	for (chr = 0; chr < 256;)
		if (!*trcset) {
			++trcset;
			chr += 32;
		} else {
			RX_subset sub = *trcset;
			RX_subset mask = 1;
			int bound = chr + 32;

			while (chr < bound) {
				if (sub & mask)
					transitions[chr] = *answer;
				++chr;
				mask <<= 1;
			}
			++trcset;
		}
}

#ifdef __STDC__
static int qlen(struct rx_superstate *q)
#else
static int qlen(q)
struct rx_superstate *q;
#endif
{
	int count = 1;
	struct rx_superstate *it;

	if (!q)
		return 0;
	for (it = q->next_recyclable; it != q; it = it->next_recyclable)
		++count;
	return count;
}

#ifdef __STDC__
static void check_cache(struct rx_cache *cache)
#else
static void check_cache(cache)
struct rx_cache *cache;
#endif
{
	struct rx_cache *you_fucked_up = 0;
	int total = cache->superstates;
	int semi = cache->semifree_superstates;

	if (semi != qlen(cache->semifree_superstate))
		check_cache(you_fucked_up);
	if ((total - semi) != qlen(cache->lru_superstate))
		check_cache(you_fucked_up);
}

/* When a superstate is old and neglected, it can enter a 
 * semi-free state.  A semi-free state is slated to die.
 * Incoming transitions to a semi-free state are re-written
 * to cause an (interpreted) fault when they are taken.
 * The fault handler revives the semi-free state, patches
 * incoming transitions back to normal, and continues.
 *
 * The idea is basicly to free in two stages, aborting 
 * between the two if the state turns out to be useful again.
 * When a free is aborted, the rescued superstate is placed
 * in the most-favored slot to maximize the time until it
 * is next semi-freed.
 */

#ifdef __STDC__
static void semifree_superstate(struct rx_cache *cache)
#else
static void semifree_superstate(cache)
struct rx_cache *cache;
#endif
{
	int disqualified = cache->semifree_superstates;

	if (disqualified == cache->superstates)
		return;
	while (cache->lru_superstate->locks) {
		cache->lru_superstate = cache->lru_superstate->next_recyclable;
		++disqualified;
		if (disqualified == cache->superstates)
			return;
	}
	{
		struct rx_superstate *it = cache->lru_superstate;

		it->next_recyclable->prev_recyclable = it->prev_recyclable;
		it->prev_recyclable->next_recyclable = it->next_recyclable;
		cache->lru_superstate = (it == it->next_recyclable
								 ? 0 : it->next_recyclable);
		if (!cache->semifree_superstate) {
			cache->semifree_superstate = it;
			it->next_recyclable = it;
			it->prev_recyclable = it;
		} else {
			it->prev_recyclable =
				cache->semifree_superstate->prev_recyclable;
			it->next_recyclable = cache->semifree_superstate;
			it->prev_recyclable->next_recyclable = it;
			it->next_recyclable->prev_recyclable = it;
		}
		{
			struct rx_distinct_future *df;

			it->is_semifree = 1;
			++cache->semifree_superstates;
			df = it->transition_refs;
			if (df) {
				df->prev_same_dest->next_same_dest = 0;
				for (df = it->transition_refs; df; df = df->next_same_dest) {
					df->future_frame.inx =
						cache->instruction_table[rx_cache_miss];
					df->future_frame.data = 0;
					df->future_frame.data_2 = (void *) df;
					/* If there are any NEXT-CHAR instruction frames that
					 * refer to this state, we convert them to CACHE-MISS frames.
					 */
					if (!df->effects
						&& (df->edge->options->next_same_super_edge[0]
							== df->edge->options))
						install_transition(df->present, &df->future_frame,
										   df->edge->cset);
				}
				df = it->transition_refs;
				df->prev_same_dest->next_same_dest = df;
			}
		}
	}
}

#ifdef __STDC__
static void
refresh_semifree_superstate(struct rx_cache *cache,
							struct rx_superstate *super)
#else
static void refresh_semifree_superstate(cache, super)
struct rx_cache *cache;
struct rx_superstate *super;
#endif
{
	struct rx_distinct_future *df;

	if (super->transition_refs) {
		super->transition_refs->prev_same_dest->next_same_dest = 0;
		for (df = super->transition_refs; df; df = df->next_same_dest) {
			df->future_frame.inx = cache->instruction_table[rx_next_char];
			df->future_frame.data = (void *) super->transitions;
			/* CACHE-MISS instruction frames that refer to this state,
			 * must be converted to NEXT-CHAR frames.
			 */
			if (!df->effects && (df->edge->options->next_same_super_edge[0]
								 == df->edge->options))
				install_transition(df->present, &df->future_frame,
								   df->edge->cset);
		}
		super->transition_refs->prev_same_dest->next_same_dest
			= super->transition_refs;
	}
	if (cache->semifree_superstate == super)
		cache->semifree_superstate = (super->prev_recyclable == super
									  ? 0 : super->prev_recyclable);
	super->next_recyclable->prev_recyclable = super->prev_recyclable;
	super->prev_recyclable->next_recyclable = super->next_recyclable;

	if (!cache->lru_superstate)
		(cache->lru_superstate
		 = super->next_recyclable = super->prev_recyclable = super);
	else {
		super->next_recyclable = cache->lru_superstate;
		super->prev_recyclable = cache->lru_superstate->prev_recyclable;
		super->next_recyclable->prev_recyclable = super;
		super->prev_recyclable->next_recyclable = super;
	}
	super->is_semifree = 0;
	--cache->semifree_superstates;
}

#ifdef __STDC__
static void
rx_refresh_this_superstate(struct rx_cache *cache,
						   struct rx_superstate *superstate)
#else
static void rx_refresh_this_superstate(cache, superstate)
struct rx_cache *cache;
struct rx_superstate *superstate;
#endif
{
	if (superstate->is_semifree)
		refresh_semifree_superstate(cache, superstate);
	else if (cache->lru_superstate == superstate)
		cache->lru_superstate = superstate->next_recyclable;
	else if (superstate != cache->lru_superstate->prev_recyclable) {
		superstate->next_recyclable->prev_recyclable
			= superstate->prev_recyclable;
		superstate->prev_recyclable->next_recyclable
			= superstate->next_recyclable;
		superstate->next_recyclable = cache->lru_superstate;
		superstate->prev_recyclable =
			cache->lru_superstate->prev_recyclable;
		superstate->next_recyclable->prev_recyclable = superstate;
		superstate->prev_recyclable->next_recyclable = superstate;
	}
}

#ifdef __STDC__
static void
release_superset_low(struct rx_cache *cache, struct rx_superset *set)
#else
static void release_superset_low(cache, set)
struct rx_cache *cache;
struct rx_superset *set;
#endif
{
	if (!--set->refs) {
		if (set->cdr)
			release_superset_low(cache, set->cdr);

		set->starts_for = 0;

		rx_hash_free
			(rx_hash_find
			 (&cache->superset_table,
			  (unsigned long) set->car ^ set->
			  id ^ (unsigned long) set->cdr, (void *) set,
			  &cache->superset_hash_rules), &cache->superset_hash_rules);
		rx_cache_free(cache, &cache->free_supersets, (char *) set);
	}
}

#ifdef __STDC__
RX_DECL void rx_release_superset(struct rx *rx, struct rx_superset *set)
#else
RX_DECL void rx_release_superset(rx, set)
struct rx *rx;
struct rx_superset *set;
#endif
{
	release_superset_low(rx->cache, set);
}

/* This tries to add a new superstate to the superstate freelist.
 * It might, as a result, free some edge pieces or hash tables.
 * If nothing can be freed because too many locks are being held, fail.
 */

#ifdef __STDC__
static int rx_really_free_superstate(struct rx_cache *cache)
#else
static int rx_really_free_superstate(cache)
struct rx_cache *cache;
#endif
{
	int locked_superstates = 0;
	struct rx_superstate *it;

	if (!cache->superstates)
		return 0;

	{
		/* This is a total guess.  The idea is that we should expect as
		 * many misses as we've recently experienced.  I.e., cache->misses
		 * should be the same as cache->semifree_superstates.
		 */
		while ((cache->hits + cache->misses) > cache->superstates_allowed) {
			cache->hits >>= 1;
			cache->misses >>= 1;
		}
		if (((cache->hits + cache->misses) * cache->semifree_superstates)
			< (cache->superstates * cache->misses)) {
			semifree_superstate(cache);
			semifree_superstate(cache);
		}
	}

	while (cache->semifree_superstate && cache->semifree_superstate->locks) {
		refresh_semifree_superstate(cache, cache->semifree_superstate);
		++locked_superstates;
		if (locked_superstates == cache->superstates)
			return 0;
	}

	if (cache->semifree_superstate) {
		it = cache->semifree_superstate;
		it->next_recyclable->prev_recyclable = it->prev_recyclable;
		it->prev_recyclable->next_recyclable = it->next_recyclable;
		cache->semifree_superstate = ((it == it->next_recyclable)
									  ? 0 : it->next_recyclable);
		--cache->semifree_superstates;
	} else {
		while (cache->lru_superstate->locks) {
			cache->lru_superstate = cache->lru_superstate->next_recyclable;
			++locked_superstates;
			if (locked_superstates == cache->superstates)
				return 0;
		}
		it = cache->lru_superstate;
		it->next_recyclable->prev_recyclable = it->prev_recyclable;
		it->prev_recyclable->next_recyclable = it->next_recyclable;
		cache->lru_superstate = ((it == it->next_recyclable)
								 ? 0 : it->next_recyclable);
	}

	if (it->transition_refs) {
		struct rx_distinct_future *df;

		for (df = it->transition_refs,
			 df->prev_same_dest->next_same_dest = 0;
			 df; df = df->next_same_dest) {
			df->future_frame.inx = cache->instruction_table[rx_cache_miss];
			df->future_frame.data = 0;
			df->future_frame.data_2 = (void *) df;
			df->future = 0;
		}
		it->transition_refs->prev_same_dest->next_same_dest =
			it->transition_refs;
	}
	{
		struct rx_super_edge *tc = it->edges;

		while (tc) {
			struct rx_distinct_future *df;
			struct rx_super_edge *tct = tc->next;

			df = tc->options;
			df->next_same_super_edge[1]->next_same_super_edge[0] = 0;
			while (df) {
				struct rx_distinct_future *dft = df;

				df = df->next_same_super_edge[0];


				if (dft->future && dft->future->transition_refs == dft) {
					dft->future->transition_refs = dft->next_same_dest;
					if (dft->future->transition_refs == dft)
						dft->future->transition_refs = 0;
				}
				dft->next_same_dest->prev_same_dest = dft->prev_same_dest;
				dft->prev_same_dest->next_same_dest = dft->next_same_dest;
				rx_cache_free(cache, &cache->free_discernable_futures,
							  (char *) dft);
			}
			rx_cache_free(cache, &cache->free_transition_classes,
						  (char *) tc);
			tc = tct;
		}
	}

	if (it->contents->superstate == it)
		it->contents->superstate = 0;
	release_superset_low(cache, it->contents);
	rx_cache_free(cache, &cache->free_superstates, (char *) it);
	--cache->superstates;
	return 1;
}

#ifdef __STDC__
static char *rx_cache_get(struct rx_cache *cache,
						  struct rx_freelist **freelist)
#else
static char *rx_cache_get(cache, freelist)
struct rx_cache *cache;
struct rx_freelist **freelist;
#endif
{
	while (!*freelist && rx_really_free_superstate(cache));
	if (!*freelist)
		return 0;
	{
		struct rx_freelist *it = *freelist;

		*freelist = it->next;
		return (char *) it;
	}
}

#ifdef __STDC__
static char *rx_cache_malloc_or_get(struct rx_cache *cache,
									struct rx_freelist **freelist,
									int bytes)
#else
static char *rx_cache_malloc_or_get(cache, freelist, bytes)
struct rx_cache *cache;
struct rx_freelist **freelist;
int bytes;
#endif
{
	if (!*freelist) {
		char *answer = rx_cache_malloc(cache, bytes);

		if (answer)
			return answer;
	}

	return rx_cache_get(cache, freelist);
}

#ifdef __STDC__
static char *rx_cache_get_superstate(struct rx_cache *cache)
#else
static char *rx_cache_get_superstate(cache)
struct rx_cache *cache;
#endif
{
	char *answer;
	int bytes = (sizeof(struct rx_superstate)
				 + cache->local_cset_size * sizeof(struct rx_inx));

	if (!cache->free_superstates
		&& (cache->superstates < cache->superstates_allowed)) {
		answer = rx_cache_malloc(cache, bytes);
		if (answer) {
			++cache->superstates;
			return answer;
		}
	}
	answer = rx_cache_get(cache, &cache->free_superstates);
	if (!answer) {
		answer = rx_cache_malloc(cache, bytes);
		if (answer)
			++cache->superstates_allowed;
	}
	++cache->superstates;
	return answer;
}



#ifdef __STDC__
static int supersetcmp(void *va, void *vb)
#else
static int supersetcmp(va, vb)
void *va;
void *vb;
#endif
{
	struct rx_superset *a = (struct rx_superset *) va;
	struct rx_superset *b = (struct rx_superset *) vb;

	return ((a == b)
			|| (a && b && (a->car == b->car) && (a->cdr == b->cdr)));
}

#ifdef __STDC__
static struct rx_hash_item *superset_allocator(struct rx_hash_rules *rules,
											   void *val)
#else
static struct rx_hash_item *superset_allocator(rules, val)
struct rx_hash_rules *rules;
void *val;
#endif
{
	struct rx_cache *cache = ((struct rx_cache *)
							  ((char *) rules
							   -

							   (unsigned
								long) (&((struct rx_cache *)
										 0)->superset_hash_rules)));
	struct rx_superset *template = (struct rx_superset *) val;
	struct rx_superset *newset
		= ((struct rx_superset *) rx_cache_malloc_or_get(cache,
														 &cache->free_supersets,
														 sizeof

														 (*template)));
	if (!newset)
		return 0;
	newset->refs = 0;
	newset->car = template->car;
	newset->id = template->car->id;
	newset->cdr = template->cdr;
	newset->superstate = 0;
	rx_protect_superset(rx, template->cdr);
	newset->hash_item.data = (void *) newset;
	newset->hash_item.binding = 0;
	return &newset->hash_item;
}

#ifdef __STDC__
static struct rx_hash *super_hash_allocator(struct rx_hash_rules *rules)
#else
static struct rx_hash *super_hash_allocator(rules)
struct rx_hash_rules *rules;
#endif
{
	struct rx_cache *cache = ((struct rx_cache *)
							  ((char *) rules
							   -

							   (unsigned
								long) (&((struct rx_cache *)
										 0)->superset_hash_rules)));
	return ((struct rx_hash *)
			rx_cache_malloc_or_get(cache, &cache->free_hash,

								   sizeof(struct rx_hash)));
}


#ifdef __STDC__
static void
super_hash_liberator(struct rx_hash *hash, struct rx_hash_rules *rules)
#else
static void super_hash_liberator(hash, rules)
struct rx_hash *hash;
struct rx_hash_rules *rules;
#endif
{
	struct rx_cache *cache = ((struct rx_cache *)

							  (char *) rules -
							  (long) (&

									  ((struct rx_cache *)
									   0)->superset_hash_rules));
	rx_cache_free(cache, &cache->free_hash, (char *) hash);
}

#ifdef __STDC__
static void
superset_hash_item_liberator(struct rx_hash_item *it,
							 struct rx_hash_rules *rules)
#else
static void superset_hash_item_liberator(it, rules)	/* Well, it does ya know. */
struct rx_hash_item *it;
struct rx_hash_rules *rules;
#endif
{
}

int rx_cache_bound = 128;
static int rx_default_cache_got = 0;

#ifdef __STDC__
static int bytes_for_cache_size(int supers, int cset_size)
#else
static int bytes_for_cache_size(supers, cset_size)
int supers;
int cset_size;
#endif
{
	/* What the hell is this? !!! */
	return (int)
		((float) supers * ((1.03 * (float) (rx_sizeof_bitset(cset_size)
											+
											sizeof(struct rx_super_edge)))
						   +
						   (1.80 *
							(float) sizeof(struct rx_possible_future)) +
						   (float) (sizeof(struct rx_superstate)
									+ cset_size * sizeof(struct rx_inx))));
}

#ifdef __STDC__
static void rx_morecore(struct rx_cache *cache)
#else
static void rx_morecore(cache)
struct rx_cache *cache;
#endif
{
	if (rx_default_cache_got >= rx_cache_bound)
		return;

	rx_default_cache_got += 16;
	cache->superstates_allowed = rx_cache_bound;
	{
		struct rx_blocklist **pos = &cache->memory;
		int size = bytes_for_cache_size(16, cache->local_cset_size);

		while (*pos)
			pos = &(*pos)->next;
		*pos = ((struct rx_blocklist *)
				malloc(size + sizeof(struct rx_blocklist)));

		if (!*pos)
			return;

		(*pos)->next = 0;
		(*pos)->bytes = size;
		cache->memory_pos = *pos;
		cache->memory_addr = (char *) *pos + sizeof(**pos);
		cache->bytes_left = size;
	}
}

static struct rx_cache default_cache = {
	{
	 supersetcmp,
	 super_hash_allocator,
	 super_hash_liberator,
	 superset_allocator,
	 superset_hash_item_liberator,
	 },
	0,
	0,
	0,
	0,
	rx_morecore,

	0,
	0,
	0,
	0,
	0,

	0,
	0,

	0,

	0,
	0,
	0,
	0,
	128,

	256,
	rx_id_instruction_table,

	{
	 0,
	 0,
	 {0},
	 {0},
	 {0}
	 }
};

/* This adds an element to a superstate set.  These sets are lists, such
 * that lists with == elements are ==.  The empty set is returned by
 * superset_cons (rx, 0, 0) and is NOT equivelent to 
 * (struct rx_superset)0.
 */

#ifdef __STDC__
RX_DECL struct rx_superset *rx_superset_cons(struct rx *rx,
											 struct rx_nfa_state *car,
											 struct rx_superset *cdr)
#else
RX_DECL struct rx_superset *rx_superset_cons(rx, car, cdr)
struct rx *rx;
struct rx_nfa_state *car;
struct rx_superset *cdr;
#endif
{
	struct rx_cache *cache = rx->cache;

	if (!car && !cdr) {
		if (!cache->empty_superset) {
			cache->empty_superset = ((struct rx_superset *)
									 rx_cache_malloc_or_get(cache,
															&cache->free_supersets,

															sizeof(struct
																   rx_superset)));
			if (!cache->empty_superset)
				return 0;
			bzero(cache->empty_superset, sizeof(struct rx_superset));

			cache->empty_superset->refs = 1000;
		}
		return cache->empty_superset;
	}
	{
		struct rx_superset template;
		struct rx_hash_item *hit;

		template.car = car;
		template.cdr = cdr;
		template.id = car->id;
		/* While hash_store will protect cdr itself it might first allocate hash
		   tables and stuff which might cause it to be garbage collected before
		   it's protected -- [gsstark:19961026.2155EST] */
		rx_protect_superset(rx, cdr);
		hit = rx_hash_store(&cache->superset_table,
							(unsigned long) car ^ car->id ^ (unsigned long)
							cdr, (void *) &template,
							&cache->superset_hash_rules);
		rx_release_superset(rx, cdr);
		return (hit ? (struct rx_superset *) hit->data : 0);
	}
}

/* This computes a union of two NFA state sets.  The sets do not have the
 * same representation though.  One is a RX_SUPERSET structure (part
 * of the superstate NFA) and the other is an NFA_STATE_SET (part of the NFA).
 */

#ifdef __STDC__
RX_DECL struct rx_superset *rx_superstate_eclosure_union
	(struct rx *rx, struct rx_superset *set, struct rx_nfa_state_set *ecl)
#else
RX_DECL struct rx_superset *rx_superstate_eclosure_union(rx, set, ecl)
struct rx *rx;
struct rx_superset *set;
struct rx_nfa_state_set *ecl;
#endif
{
	if (!ecl)
		return set;

	if (!set->car)
		return rx_superset_cons(rx, ecl->car,
								rx_superstate_eclosure_union(rx, set,
															 ecl->cdr));
	if (set->car == ecl->car)
		return rx_superstate_eclosure_union(rx, set, ecl->cdr);

	{
		struct rx_superset *tail;
		struct rx_nfa_state *first;

		if (set->car > ecl->car) {
			tail = rx_superstate_eclosure_union(rx, set->cdr, ecl);
			first = set->car;
		} else {
			tail = rx_superstate_eclosure_union(rx, set, ecl->cdr);
			first = ecl->car;
		}
		if (!tail)
			return 0;
		else {
			struct rx_superset *answer;

			answer = rx_superset_cons(rx, first, tail);
			if (!answer) {
				rx_protect_superset(rx, tail);
				rx_release_superset(rx, tail);
				return 0;
			} else
				return answer;
		}
	}
}




/*
 * This makes sure that a list of rx_distinct_futures contains
 * a future for each possible set of side effects in the eclosure
 * of a given state.  This is some of the work of filling in a
 * superstate transition. 
 */

#ifdef __STDC__
static struct rx_distinct_future *include_futures(struct rx *rx, struct rx_distinct_future
												  *df, struct rx_nfa_state
												  *state, struct rx_superstate
												  *superstate)
#else
static struct rx_distinct_future *include_futures(rx, df, state,
												  superstate)
struct rx *rx;
struct rx_distinct_future *df;
struct rx_nfa_state *state;
struct rx_superstate *superstate;
#endif
{
	struct rx_possible_future *future;
	struct rx_cache *cache = rx->cache;

	for (future = state->futures; future; future = future->next) {
		struct rx_distinct_future *dfp;
		struct rx_distinct_future *insert_before = 0;

		if (df)
			df->next_same_super_edge[1]->next_same_super_edge[0] = 0;
		for (dfp = df; dfp; dfp = dfp->next_same_super_edge[0])
			if (dfp->effects == future->effects)
				break;
			else {
				int order =

					rx->se_list_cmp(rx, dfp->effects, future->effects);
				if (order > 0) {
					insert_before = dfp;
					dfp = 0;
					break;
				}
			}
		if (df)
			df->next_same_super_edge[1]->next_same_super_edge[0] = df;
		if (!dfp) {
			dfp = ((struct rx_distinct_future *)
				   rx_cache_malloc_or_get(cache,
										  &cache->free_discernable_futures,

										  sizeof(struct
												 rx_distinct_future)));
			if (!dfp)
				return 0;
			if (!df) {
				df = insert_before = dfp;
				df->next_same_super_edge[0] = df->next_same_super_edge[1] =
					df;
			} else if (!insert_before)
				insert_before = df;
			else if (insert_before == df)
				df = dfp;

			dfp->next_same_super_edge[0] = insert_before;
			dfp->next_same_super_edge[1]
				= insert_before->next_same_super_edge[1];
			dfp->next_same_super_edge[1]->next_same_super_edge[0] = dfp;
			dfp->next_same_super_edge[0]->next_same_super_edge[1] = dfp;
			dfp->next_same_dest = dfp->prev_same_dest = dfp;
			dfp->future = 0;
			dfp->present = superstate;
			dfp->future_frame.inx = rx->instruction_table[rx_cache_miss];
			dfp->future_frame.data = 0;
			dfp->future_frame.data_2 = (void *) dfp;
			dfp->side_effects_frame.inx
				= rx->instruction_table[rx_do_side_effects];
			dfp->side_effects_frame.data = 0;
			dfp->side_effects_frame.data_2 = (void *) dfp;
			dfp->effects = future->effects;
		}
	}
	return df;
}


/* This constructs a new superstate from its state set.  The only 
 * complexity here is memory management.
 */
#ifdef __STDC__
RX_DECL struct rx_superstate *rx_superstate(struct rx *rx,
											struct rx_superset *set)
#else
RX_DECL struct rx_superstate *rx_superstate(rx, set)
struct rx *rx;
struct rx_superset *set;
#endif
{
	struct rx_cache *cache = rx->cache;
	struct rx_superstate *superstate = 0;

	/* Does the superstate already exist in the cache? */
	if (set->superstate) {
		if (set->superstate->rx_id != rx->rx_id) {
			/* Aha.  It is in the cache, but belongs to a superstate
			 * that refers to an NFA that no longer exists.
			 * (We know it no longer exists because it was evidently
			 *  stored in the same region of memory as the current nfa
			 *  yet it has a different id.)
			 */
			superstate = set->superstate;
			if (!superstate->is_semifree) {
				if (cache->lru_superstate == superstate) {
					cache->lru_superstate = superstate->next_recyclable;
					if (cache->lru_superstate == superstate)
						cache->lru_superstate = 0;
				}
				{
					superstate->next_recyclable->prev_recyclable
						= superstate->prev_recyclable;
					superstate->prev_recyclable->next_recyclable
						= superstate->next_recyclable;
					if (!cache->semifree_superstate) {
						(cache->semifree_superstate
						 = superstate->next_recyclable
						 = superstate->prev_recyclable = superstate);
					} else {
						superstate->next_recyclable =
							cache->semifree_superstate;
						superstate->prev_recyclable =
							cache->semifree_superstate->prev_recyclable;
						superstate->next_recyclable->prev_recyclable =
							superstate;
						superstate->prev_recyclable->next_recyclable =
							superstate;
						cache->semifree_superstate = superstate;
					}
					++cache->semifree_superstates;
				}
			}
			set->superstate = 0;
			goto handle_cache_miss;
		}
		++cache->hits;
		superstate = set->superstate;

		rx_refresh_this_superstate(cache, superstate);
		return superstate;
	}

  handle_cache_miss:

	/* This point reached only for cache misses. */
	++cache->misses;
#if RX_DEBUG
	if (rx_debug_trace > 1) {
		struct rx_superset *setp = set;

		fprintf(stderr, "Building a superstet %d(%d): ", rx->rx_id, set);
		while (setp) {
			fprintf(stderr, "%d ", setp->id);
			setp = setp->cdr;
		}
		fprintf(stderr, "(%d)\n", set);
	}
#endif
	superstate = (struct rx_superstate *) rx_cache_get_superstate(cache);
	if (!superstate)
		return 0;

	if (!cache->lru_superstate)
		(cache->lru_superstate
		 = superstate->next_recyclable
		 = superstate->prev_recyclable = superstate);
	else {
		superstate->next_recyclable = cache->lru_superstate;
		superstate->prev_recyclable =
			cache->lru_superstate->prev_recyclable;
		(superstate->prev_recyclable->next_recyclable =
		 superstate->next_recyclable->prev_recyclable = superstate);
	}
	superstate->rx_id = rx->rx_id;
	superstate->transition_refs = 0;
	superstate->locks = 0;
	superstate->is_semifree = 0;
	set->superstate = superstate;
	superstate->contents = set;
	rx_protect_superset(rx, set);
	superstate->edges = 0;
	{
		int x;

		/* None of the transitions from this superstate are known yet. */
		for (x = 0; x < rx->local_cset_size; ++x) {	/* &&&&& 3.8 % */
			struct rx_inx *ifr = &superstate->transitions[x];

			ifr->inx = rx->instruction_table[rx_cache_miss];
			ifr->data = ifr->data_2 = 0;
		}
	}
	return superstate;
}


/* This computes the destination set of one edge of the superstate NFA.
 * Note that a RX_DISTINCT_FUTURE is a superstate edge.
 * Returns 0 on an allocation failure.
 */

#ifdef __STDC__
static int solve_destination(struct rx *rx, struct rx_distinct_future *df)
#else
static int solve_destination(rx, df)
struct rx *rx;
struct rx_distinct_future *df;
#endif
{
	struct rx_super_edge *tc = df->edge;
	struct rx_superset *nfa_state;
	struct rx_superset *nil_set = rx_superset_cons(rx, 0, 0);
	struct rx_superset *solution = nil_set;
	struct rx_superstate *dest;

	rx_protect_superset(rx, solution);
	/* Iterate over all NFA states in the state set of this superstate. */
	for (nfa_state = df->present->contents;
		 nfa_state->car; nfa_state = nfa_state->cdr) {
		struct rx_nfa_edge *e;

		/* Iterate over all edges of each NFA state. */
		for (e = nfa_state->car->edges; e; e = e->next)
			/* If we find an edge that is labeled with 
			   * the characters we are solving for.....
			 */
			if (rx_bitset_is_subset(rx->local_cset_size,
									tc->cset, e->params.cset)) {
				struct rx_nfa_state *n = e->dest;
				struct rx_possible_future *pf;

				/* ....search the partial epsilon closures of the destination
				 * of that edge for a path that involves the same set of
				 * side effects we are solving for.
				 * If we find such a RX_POSSIBLE_FUTURE, we add members to the
				 * stateset we are computing.
				 */
				for (pf = n->futures; pf; pf = pf->next)
					if (pf->effects == df->effects) {
						struct rx_superset *old_sol;

						old_sol = solution;
						solution =
							rx_superstate_eclosure_union(rx, solution,
														 pf->destset);
						if (!solution)
							return 0;
						rx_protect_superset(rx, solution);
						rx_release_superset(rx, old_sol);
					}
			}
	}
	/* It is possible that the RX_DISTINCT_FUTURE we are working on has 
	 * the empty set of NFA states as its definition.  In that case, this
	 * is a failure point.
	 */
	if (solution == nil_set) {
		df->future_frame.inx = (void *) rx_backtrack;
		df->future_frame.data = 0;
		df->future_frame.data_2 = 0;
		return 1;
	}
	dest = rx_superstate(rx, solution);
	rx_release_superset(rx, solution);
	if (!dest)
		return 0;

	{
		struct rx_distinct_future *dft;

		dft = df;
		df->prev_same_dest->next_same_dest = 0;
		while (dft) {
			dft->future = dest;
			dft->future_frame.inx = rx->instruction_table[rx_next_char];
			dft->future_frame.data = (void *) dest->transitions;
			dft = dft->next_same_dest;
		}
		df->prev_same_dest->next_same_dest = df;
	}
	if (!dest->transition_refs)
		dest->transition_refs = df;
	else {
		struct rx_distinct_future *dft =

			dest->transition_refs->next_same_dest;
		dest->transition_refs->next_same_dest = df->next_same_dest;
		df->next_same_dest->prev_same_dest = dest->transition_refs;
		df->next_same_dest = dft;
		dft->prev_same_dest = df;
	}
	return 1;
}


/* This takes a superstate and a character, and computes some edges
 * from the superstate NFA.  In particular, this computes all edges
 * that lead from SUPERSTATE given CHR.   This function also 
 * computes the set of characters that share this edge set.
 * This returns 0 on allocation error.
 * The character set and list of edges are returned through 
 * the paramters CSETOUT and DFOUT.
} */

#ifdef __STDC__
static int
compute_super_edge(struct rx *rx, struct rx_distinct_future **dfout,
				   rx_Bitset csetout, struct rx_superstate *superstate,
				   unsigned char chr)
#else
static int compute_super_edge(rx, dfout, csetout, superstate, chr)
struct rx *rx;
struct rx_distinct_future **dfout;
rx_Bitset csetout;
struct rx_superstate *superstate;
unsigned char chr;
#endif
{
	struct rx_superset *stateset = superstate->contents;

	/* To compute the set of characters that share edges with CHR, 
	 * we start with the full character set, and subtract.
	 */
	rx_bitset_universe(rx->local_cset_size, csetout);
	*dfout = 0;

	/* Iterate over the NFA states in the superstate state-set. */
	while (stateset->car) {
		struct rx_nfa_edge *e;

		for (e = stateset->car->edges; e; e = e->next)
			if (RX_bitset_member(e->params.cset, chr)) {
				/* If we find an NFA edge that applies, we make sure there
				 * are corresponding edges in the superstate NFA.
				 */
				{
					struct rx_distinct_future *saved;

					saved = *dfout;
					*dfout =
						include_futures(rx, *dfout, e->dest, superstate);
					if (!*dfout) {
						struct rx_distinct_future *df;

						df = saved;
						if (df)
							df->
								next_same_super_edge
								[1]->next_same_super_edge[0] = 0;
						while (df) {
							struct rx_distinct_future *dft;

							dft = df;
							df = df->next_same_super_edge[0];

							if (dft->future
								&& dft->future->transition_refs == dft) {
								dft->future->transition_refs =
									dft->next_same_dest;
								if (dft->future->transition_refs == dft)
									dft->future->transition_refs = 0;
							}
							dft->next_same_dest->prev_same_dest =
								dft->prev_same_dest;
							dft->prev_same_dest->next_same_dest =
								dft->next_same_dest;
							rx_cache_free(rx->cache,
										  &rx->
										  cache->free_discernable_futures,
										  (char *) dft);
						}
						return 0;
					}
				}
				/* We also trim the character set a bit. */
				rx_bitset_intersection(rx->local_cset_size,
									   csetout, e->params.cset);
			} else
				/* An edge that doesn't apply at least tells us some characters
				 * that don't share the same edge set as CHR.
				 */
				rx_bitset_difference(rx->local_cset_size, csetout,
									 e->params.cset);
		stateset = stateset->cdr;
	}
	return 1;
}


/* This is a constructor for RX_SUPER_EDGE structures.  These are
 * wrappers for lists of superstate NFA edges that share character sets labels.
 * If a transition class contains more than one rx_distinct_future (superstate
 * edge), then it represents a non-determinism in the superstate NFA.
 */


#ifdef __STDC__
static struct rx_super_edge *rx_super_edge(struct rx *rx,
										   struct rx_superstate *super,
										   rx_Bitset cset,
										   struct rx_distinct_future *df)
#else
static struct rx_super_edge *rx_super_edge(rx, super, cset, df)
struct rx *rx;
struct rx_superstate *super;
rx_Bitset cset;
struct rx_distinct_future *df;
#endif
{
	struct rx_super_edge *tc =
		(struct rx_super_edge *) rx_cache_malloc_or_get
		(rx->cache, &rx->cache->free_transition_classes,
		 sizeof(struct rx_super_edge) +

		 rx_sizeof_bitset(rx->local_cset_size));

	if (!tc)
		return 0;
	tc->next = super->edges;
	super->edges = tc;
	tc->rx_backtrack_frame.inx = rx->instruction_table[rx_backtrack_point];
	tc->rx_backtrack_frame.data = 0;
	tc->rx_backtrack_frame.data_2 = (void *) tc;
	tc->options = df;
	tc->cset = (rx_Bitset) ((char *) tc + sizeof(*tc));
	rx_bitset_assign(rx->local_cset_size, tc->cset, cset);
	if (df) {
		struct rx_distinct_future *dfp = df;

		df->next_same_super_edge[1]->next_same_super_edge[0] = 0;
		while (dfp) {
			dfp->edge = tc;
			dfp = dfp->next_same_super_edge[0];
		}
		df->next_same_super_edge[1]->next_same_super_edge[0] = df;
	}
	return tc;
}


/* There are three kinds of cache miss.  The first occurs when a
 * transition is taken that has never been computed during the
 * lifetime of the source superstate.  That cache miss is handled by
 * calling COMPUTE_SUPER_EDGE.  The second kind of cache miss
 * occurs when the destination superstate of a transition doesn't
 * exist.  SOLVE_DESTINATION is used to construct the destination superstate.
 * Finally, the third kind of cache miss occurs when the destination
 * superstate of a transition is in a `semi-free state'.  That case is
 * handled by UNFREE_SUPERSTATE.
 *
 * The function of HANDLE_CACHE_MISS is to figure out which of these
 * cases applies.
 */


#ifdef __STDC__
static void
install_partial_transition(struct rx_superstate *super,
						   struct rx_inx *answer,
						   RX_subset set, int offset)
#else
static void install_partial_transition(super, answer, set, offset)
struct rx_superstate *super;
struct rx_inx *answer;
RX_subset set;
int offset;
#endif
{
	int start = offset;
	int end = start + 32;
	RX_subset pos = 1;
	struct rx_inx *transitions = super->transitions;

	while (start < end) {
		if (set & pos)
			transitions[start] = *answer;
		pos <<= 1;
		++start;
	}
}

#ifdef __STDC__
RX_DECL struct rx_inx *rx_handle_cache_miss
	(struct rx *rx, struct rx_superstate *super, unsigned char chr,
	 void *data)
#else
RX_DECL struct rx_inx *rx_handle_cache_miss(rx, super, chr, data)
struct rx *rx;
struct rx_superstate *super;
unsigned char chr;
void *data;
#endif
{
	int offset = chr / RX_subset_bits;
	struct rx_distinct_future *df = data;

	if (!df) {					/* must be the shared_cache_miss_frame */
		/* Perhaps this is just a transition waiting to be filled. */
		struct rx_super_edge *tc;
		RX_subset mask = rx_subset_singletons[chr % RX_subset_bits];

		for (tc = super->edges; tc; tc = tc->next)
			if (tc->cset[offset] & mask) {
				struct rx_inx *answer;

				df = tc->options;
				answer =
					((tc->options->next_same_super_edge[0] !=
					  tc->options) ? &tc->
					 rx_backtrack_frame : (df->effects ?
										   &df->side_effects_frame :
										   &df->future_frame));
				install_partial_transition(super, answer, tc->cset[offset],
										   offset * 32);
				return answer;
			}
		/* Otherwise, it's a flushed or  newly encountered edge. */
		{
			char cset_space[1024];	/* this limit is far from unreasonable */
			rx_Bitset trcset;
			struct rx_inx *answer;

			if (rx_sizeof_bitset(rx->local_cset_size) > sizeof(cset_space))
				return 0;		/* If the arbitrary limit is hit, always fail */
			/* cleanly. */
			trcset = (rx_Bitset) cset_space;
			rx_lock_superstate(rx, super);
			if (!compute_super_edge(rx, &df, trcset, super, chr)) {
				rx_unlock_superstate(rx, super);
				return 0;
			}
			if (!df) {			/* We just computed the fail transition. */
				static struct rx_inx
					shared_fail_frame = { 0, 0, (void *) rx_backtrack, 0 };

				answer = &shared_fail_frame;
			} else {
				tc = rx_super_edge(rx, super, trcset, df);
				if (!tc) {
					rx_unlock_superstate(rx, super);
					return 0;
				}
				answer =
					((tc->options->next_same_super_edge[0] !=
					  tc->options) ? &tc->
					 rx_backtrack_frame : (df->effects ?
										   &df->side_effects_frame :
										   &df->future_frame));
			}
			install_partial_transition(super, answer,
									   trcset[offset], offset * 32);
			rx_unlock_superstate(rx, super);
			return answer;
		}
	} else if (df->future) {	/* A cache miss on an edge with a future? Must be
								   * a semi-free destination. */
		if (df->future->is_semifree)
			refresh_semifree_superstate(rx->cache, df->future);
		return &df->future_frame;
	} else
		/* no future superstate on an existing edge */
	{
		rx_lock_superstate(rx, super);
		if (!solve_destination(rx, df)) {
			rx_unlock_superstate(rx, super);
			return 0;
		}
		if (!df->effects
			&& (df->edge->options->next_same_super_edge[0] ==
				df->edge->options)) install_partial_transition(super,
															   &df->future_frame,
															   df->
															   edge->cset
															   [offset],
															   offset *
															   32);
		rx_unlock_superstate(rx, super);
		return &df->future_frame;
	}
}




/* The rest of the code provides a regex.c compatable interface. */


__const__ char *re_error_msg[] = {
	0,							/* REG_NOUT */
	"No match",					/* REG_NOMATCH */
	"Invalid regular expression",	/* REG_BADPAT */
	"Invalid collation character",	/* REG_ECOLLATE */
	"Invalid character class name",	/* REG_ECTYPE */
	"Trailing backslash",		/* REG_EESCAPE */
	"Invalid back reference",	/* REG_ESUBREG */
	"Unmatched [ or [^",		/* REG_EBRACK */
	"Unmatched ( or \\(",		/* REG_EPAREN */
	"Unmatched \\{",			/* REG_EBRACE */
	"Invalid content of \\{\\}",	/* REG_BADBR */
	"Invalid range end",		/* REG_ERANGE */
	"Memory exhausted",			/* REG_ESPACE */
	"Invalid preceding regular expression",	/* REG_BADRPT */
	"Premature end of regular expression",	/* REG_EEND */
	"Regular expression too big",	/* REG_ESIZE */
	"Unmatched ) or \\)",		/* REG_ERPAREN */
};



/* 
 * Macros used while compiling patterns.
 *
 * By convention, PEND points just past the end of the uncompiled pattern,
 * P points to the read position in the pattern.  `translate' is the name
 * of the translation table (`TRANSLATE' is the name of a macro that looks
 * things up in `translate').
 */


/*
 * Fetch the next character in the uncompiled pattern---translating it 
 * if necessary. *Also cast from a signed character in the constant
 * string passed to us by the user to an unsigned char that we can use
 * as an array index (in, e.g., `translate').
 */
#define PATFETCH(c)							\
 do {if (p == pend) return REG_EEND;					\
    c = (unsigned char) *p++;						\
    c = translate[c];		 					\
 } while (0)

/* 
 * Fetch the next character in the uncompiled pattern, with no
 * translation.
 */
#define PATFETCH_RAW(c)							\
  do {if (p == pend) return REG_EEND;					\
    c = (unsigned char) *p++; 						\
  } while (0)

/* Go backwards one character in the pattern.  */
#define PATUNFETCH p--


#define TRANSLATE(d) translate[(unsigned char) (d)]

typedef unsigned regnum_t;

/* Since offsets can go either forwards or backwards, this type needs to
 * be able to hold values from -(MAX_BUF_SIZE - 1) to MAX_BUF_SIZE - 1.
 */
typedef int pattern_offset_t;

typedef struct {
	struct rexp_node **top_expression;	/* was begalt */
	struct rexp_node **last_expression;	/* was laststart */
	pattern_offset_t inner_group_offset;
	regnum_t regnum;
} compile_stack_elt_t;
typedef struct {
	compile_stack_elt_t *stack;
	unsigned size;
	unsigned avail;				/* Offset of next open position.  */
} compile_stack_type;

static boolean group_in_compile_stack(compile_stack_type, regnum_t);
static reg_errcode_t
compile_range(struct re_pattern_buffer *, rx_Bitset,
			  __const__ char **, __const__ char *,
			  unsigned char *, reg_syntax_t, rx_Bitset, char *);
static void find_backrefs(char *, struct rexp_node *,

						  struct re_se_params *);
static int compute_fastset(struct re_pattern_buffer *, struct rexp_node *);
static int is_anchored(struct rexp_node *, rx_side_effect);
static struct rexp_node
*remove_unecessary_side_effects

	(struct rx *, char *, struct rexp_node *, struct re_se_params *);
static int pointless_if_repeated(struct rexp_node *,

								 struct re_se_params *);
static int registers_on_stack(struct re_pattern_buffer *,
							  struct rexp_node *,

							  int, struct re_se_params *);
static int has_any_se(struct rx *, struct rexp_node *);
static int has_non_idempotent_epsilon_path

	(struct rx *, struct rexp_node *, struct re_se_params *);
static int begins_with_complex_se(struct rx *, struct rexp_node *);
static void speed_up_alt(struct rx *, struct rexp_node *, int);
RX_DECL reg_errcode_t

rx_compile(__const__ char *, int, reg_syntax_t,
		   struct re_pattern_buffer *);
RX_DECL void rx_blow_up_fastmap(struct re_pattern_buffer *);
static __inline__ enum rx_get_burst_return
re_search_2_get_burst(struct rx_string_position *, void *, int);
static __inline__ enum rx_back_check_return
re_search_2_back_check(struct rx_string_position *, int,
					   int, unsigned char *, void *, int);
static __inline__ int
re_search_2_fetch_char(struct rx_string_position *, int, void *, int);


#define INIT_COMPILE_STACK_SIZE 32

#define COMPILE_STACK_EMPTY  (compile_stack.avail == 0)
#define COMPILE_STACK_FULL  (compile_stack.avail == compile_stack.size)

/* The next available element.  */
#define COMPILE_STACK_TOP (compile_stack.stack[compile_stack.avail])


/* Set the bit for character C in a list.  */
#define SET_LIST_BIT(c)                               \
  (b[((unsigned char) (c)) / CHARBITS]               \
   |= 1 << (((unsigned char) c) % CHARBITS))

/* Get the next unsigned number in the uncompiled pattern.  */
#define GET_UNSIGNED_NUMBER(num) 					\
  { if (p != pend)							\
     {									\
       PATFETCH (c); 							\
       while (isdigit (c)) 						\
         { 								\
           if (num < 0)							\
              num = 0;							\
           num = num * 10 + c - '0'; 					\
           if (p == pend) 						\
              break; 							\
           PATFETCH (c);						\
         } 								\
       } 								\
    }

#define CHAR_CLASS_MAX_LENGTH  6	/* Namely, `xdigit'.  */

#define IS_CHAR_CLASS(string)						\
   (!strcmp (string, "alpha") || !strcmp (string, "upper")		\
    || !strcmp (string, "lower") || !strcmp (string, "digit")		\
    || !strcmp (string, "alnum") || !strcmp (string, "xdigit")		\
    || !strcmp (string, "space") || !strcmp (string, "print")		\
    || !strcmp (string, "punct") || !strcmp (string, "graph")		\
    || !strcmp (string, "cntrl") || !strcmp (string, "blank"))


/* These predicates are used in regex_compile. */

/* P points to just after a ^ in PATTERN.  Return true if that ^ comes
 * after an alternative or a begin-subexpression.  We assume there is at
 * least one character before the ^.  
 */

#ifdef __STDC__
static boolean
at_begline_loc_p(__const__ char *pattern, __const__ char *p,
				 reg_syntax_t syntax)
#else
static boolean at_begline_loc_p(pattern, p, syntax)
__const__ char *pattern;
__const__ char *p;
reg_syntax_t syntax;
#endif
{
	__const__ char *prev = p - 2;
	boolean prev_prev_backslash = ((prev > pattern) && (prev[-1] == '\\'));

	return (					/* After a subexpression?  */
			   ((*prev == '(') && ((syntax & RE_NO_BK_PARENS) || prev_prev_backslash))
			   ||
			   /* After an alternative?  */
			   ((*prev == '|') && ((syntax & RE_NO_BK_VBAR) || prev_prev_backslash))
		);
}

/* The dual of at_begline_loc_p.  This one is for $.  We assume there is
 * at least one character after the $, i.e., `P < PEND'.
 */

#ifdef __STDC__
static boolean
at_endline_loc_p(__const__ char *p, __const__ char *pend, int syntax)
#else
static boolean at_endline_loc_p(p, pend, syntax)
__const__ char *p;
__const__ char *pend;
int syntax;
#endif
{
	__const__ char *next = p;
	boolean next_backslash = (*next == '\\');
	__const__ char *next_next = (p + 1 < pend) ? (p + 1) : 0;

	return (
			   /* Before a subexpression?  */
			   ((syntax & RE_NO_BK_PARENS)
				? (*next == ')')
				: (next_backslash && next_next && (*next_next == ')')))
			   ||
			   /* Before an alternative?  */
			   ((syntax & RE_NO_BK_VBAR)
				? (*next == '|')
				: (next_backslash && next_next && (*next_next == '|')))
		);
}


unsigned char rx_id_translation[256] = {
	0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
	10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
	20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
	30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
	40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
	50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
	60, 61, 62, 63, 64, 65, 66, 67, 68, 69,
	70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
	80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
	90, 91, 92, 93, 94, 95, 96, 97, 98, 99,

	100, 101, 102, 103, 104, 105, 106, 107, 108, 109,
	110, 111, 112, 113, 114, 115, 116, 117, 118, 119,
	120, 121, 122, 123, 124, 125, 126, 127, 128, 129,
	130, 131, 132, 133, 134, 135, 136, 137, 138, 139,
	140, 141, 142, 143, 144, 145, 146, 147, 148, 149,
	150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
	160, 161, 162, 163, 164, 165, 166, 167, 168, 169,
	170, 171, 172, 173, 174, 175, 176, 177, 178, 179,
	180, 181, 182, 183, 184, 185, 186, 187, 188, 189,
	190, 191, 192, 193, 194, 195, 196, 197, 198, 199,

	200, 201, 202, 203, 204, 205, 206, 207, 208, 209,
	210, 211, 212, 213, 214, 215, 216, 217, 218, 219,
	220, 221, 222, 223, 224, 225, 226, 227, 228, 229,
	230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
	240, 241, 242, 243, 244, 245, 246, 247, 248, 249,
	250, 251, 252, 253, 254, 255
};

/* The compiler keeps an inverted translation table.
 * This looks up/inititalize elements.
 * VALID is an array of booleans that validate CACHE.
 */

#ifdef __STDC__
static rx_Bitset
inverse_translation(struct re_pattern_buffer *rxb,
					char *valid, rx_Bitset cache,
					unsigned char *translate, int c)
#else
static rx_Bitset inverse_translation(rxb, valid, cache, translate, c)
struct re_pattern_buffer *rxb;
char *valid;
rx_Bitset cache;
unsigned char *translate;
int c;
#endif
{
	rx_Bitset cs

		= cache + c * rx_bitset_numb_subsets(rxb->rx.local_cset_size);

	if (!valid[c]) {
		int x;
		int c_tr = TRANSLATE(c);

		rx_bitset_null(rxb->rx.local_cset_size, cs);
		for (x = 0; x < 256; ++x)	/* &&&& 13.37 */
			if (TRANSLATE(x) == c_tr)
				RX_bitset_enjoin(cs, x);
		valid[c] = 1;
	}
	return cs;
}




/* More subroutine declarations and macros for regex_compile.  */

/* Returns true if REGNUM is in one of COMPILE_STACK's elements and 
   false if it's not.  */

#ifdef __STDC__
static boolean
group_in_compile_stack(compile_stack_type compile_stack, regnum_t regnum)
#else
static boolean group_in_compile_stack(compile_stack, regnum)
compile_stack_type compile_stack;
regnum_t regnum;
#endif
{
	int this_element;

	for (this_element = compile_stack.avail - 1;
		 this_element >= 0; this_element--)
		if (compile_stack.stack[this_element].regnum == regnum)
			return true;

	return false;
}


/*
 * Read the ending character of a range (in a bracket expression) from the
 * uncompiled pattern *P_PTR (which ends at PEND).  We assume the
 * starting character is in `P[-2]'.  (`P[-1]' is the character `-'.)
 * Then we set the translation of all bits between the starting and
 * ending characters (inclusive) in the compiled pattern B.
 * 
 * Return an error code.
 * 
 * We use these short variable names so we can use the same macros as
 * `regex_compile' itself.  
 */

#ifdef __STDC__
static reg_errcode_t
compile_range(struct re_pattern_buffer *rxb, rx_Bitset cs,
			  __const__ char **p_ptr, __const__ char *pend,
			  unsigned char *translate, reg_syntax_t syntax,
			  rx_Bitset inv_tr, char *valid_inv_tr)
#else
static reg_errcode_t
compile_range(rxb, cs, p_ptr, pend, translate, syntax, inv_tr,
			  valid_inv_tr)
struct re_pattern_buffer *rxb;
rx_Bitset cs;
__const__ char **p_ptr;
__const__ char *pend;
unsigned char *translate;
reg_syntax_t syntax;
rx_Bitset inv_tr;
char *valid_inv_tr;
#endif
{
	unsigned this_char;

	__const__ char *p = *p_ptr;

	unsigned char range_end;
	unsigned char range_start = TRANSLATE(p[-2]);

	if (p == pend)
		return REG_ERANGE;

	PATFETCH(range_end);

	(*p_ptr)++;

	if (range_start > range_end)
		return syntax & RE_NO_EMPTY_RANGES ? REG_ERANGE : REG_NOERROR;

	for (this_char = range_start; this_char <= range_end; this_char++) {
		rx_Bitset it =
			inverse_translation(rxb, valid_inv_tr, inv_tr, translate,

								this_char);

		rx_bitset_union(rxb->rx.local_cset_size, cs, it);
	}

	return REG_NOERROR;
}


/* This searches a regexp for backreference side effects.
 * It fills in the array OUT with 1 at the index of every register pair
 * referenced by a backreference.
 *
 * This is used to help optimize patterns for searching.  The information is
 * useful because, if the caller doesn't want register values, backreferenced
 * registers are the only registers for which we need rx_backtrack.
 */

#ifdef __STDC__
static void
find_backrefs(char *out, struct rexp_node *rexp,
			  struct re_se_params *params)
#else
static void find_backrefs(out, rexp, params)
char *out;
struct rexp_node *rexp;
struct re_se_params *params;
#endif
{
	if (rexp)
		switch (rexp->type) {
		case r_cset:
		case r_data:
			return;
		case r_alternate:
		case r_concat:
		case r_opt:
		case r_star:
		case r_2phase_star:
			find_backrefs(out, rexp->params.pair.left, params);
			find_backrefs(out, rexp->params.pair.right, params);
			return;
		case r_side_effect:
			if (((long) rexp->params.side_effect >= 0)
				&& (params[(long) rexp->params.side_effect].se ==
					re_se_backref))
					out[params[(long) rexp->params.side_effect].op1] = 1;
			return;
		}
}



/* Returns 0 unless the pattern can match the empty string. */

#ifdef __STDC__
static int
compute_fastset(struct re_pattern_buffer *rxb, struct rexp_node *rexp)
#else
static int compute_fastset(rxb, rexp)
struct re_pattern_buffer *rxb;
struct rexp_node *rexp;
#endif
{
	if (!rexp)
		return 1;
	switch (rexp->type) {
	case r_data:
		return 1;
	case r_cset:
	{
		rx_bitset_union(rxb->rx.local_cset_size,
						rxb->fastset, rexp->params.cset);
	}
		return 0;
	case r_concat:
		return (compute_fastset(rxb, rexp->params.pair.left)
				&& compute_fastset(rxb, rexp->params.pair.right));
	case r_2phase_star:
		compute_fastset(rxb, rexp->params.pair.left);
		/* compute_fastset (rxb, rexp->params.pair.right);  nope... */
		return 1;
	case r_alternate:
		return !!(compute_fastset(rxb, rexp->params.pair.left)
				  + compute_fastset(rxb, rexp->params.pair.right));
	case r_opt:
	case r_star:
		compute_fastset(rxb, rexp->params.pair.left);
		return 1;
	case r_side_effect:
		return 1;
	}

	/* this should never happen */
	return 0;
}


/* returns
 *  1 -- yes, definately anchored by the given side effect.
 *  2 -- maybe anchored, maybe the empty string.
 *  0 -- definately not anchored
 *  There is simply no other possibility.
 */

#ifdef __STDC__
static int is_anchored(struct rexp_node *rexp, rx_side_effect se)
#else
static int is_anchored(rexp, se)
struct rexp_node *rexp;
rx_side_effect se;
#endif
{
	if (!rexp)
		return 2;
	switch (rexp->type) {
	case r_cset:
	case r_data:
		return 0;
	case r_concat:
	case r_2phase_star:
	{
		int l = is_anchored(rexp->params.pair.left, se);

		return (l == 2 ? is_anchored(rexp->params.pair.right, se) : l);
	}
	case r_alternate:
	{
		int l = is_anchored(rexp->params.pair.left, se);
		int r = l ? is_anchored(rexp->params.pair.right, se) : 0;

		if (l == r)
			return l;
		else if ((l == 0) || (r == 0))
			return 0;
		else
			return 2;
	}
	case r_opt:
	case r_star:
		return is_anchored(rexp->params.pair.left, se) ? 2 : 0;

	case r_side_effect:
		return ((rexp->params.side_effect == se)
				? 1 : 2);
	}

	/* this should never happen */
	return 0;
}


/* This removes register assignments that aren't required by backreferencing.
 * This can speed up explore_future, especially if it eliminates
 * non-determinism in the superstate NFA.
 * 
 * NEEDED is an array of characters, presumably filled in by FIND_BACKREFS.
 * The non-zero elements of the array indicate which register assignments
 * can NOT be removed from the expression.
 */

#ifdef __STDC__
static struct rexp_node *remove_unecessary_side_effects(struct rx *rx,
														char *needed,
														struct rexp_node
														*rexp,
														struct re_se_params
														*params)
#else
static struct rexp_node *remove_unecessary_side_effects(rx, needed, rexp,
														params)
struct rx *rx;
char *needed;
struct rexp_node *rexp;
struct re_se_params *params;
#endif
{
	struct rexp_node *l;
	struct rexp_node *r;

	if (!rexp)
		return 0;
	else
		switch (rexp->type) {
		case r_cset:
		case r_data:
			return rexp;
		case r_alternate:
		case r_concat:
		case r_2phase_star:
			l = remove_unecessary_side_effects(rx, needed,
											   rexp->params.pair.left,
											   params);
			r =
				remove_unecessary_side_effects(rx, needed,
											   rexp->params.pair.right,
											   params);
			if ((l && r) || (rexp->type != r_concat)) {
				rexp->params.pair.left = l;
				rexp->params.pair.right = r;
				return rexp;
			} else {
				rexp->params.pair.left = rexp->params.pair.right = 0;
				rx_free_rexp(rx, rexp);
				return l ? l : r;
			}
		case r_opt:
		case r_star:
			l = remove_unecessary_side_effects(rx, needed,
											   rexp->params.pair.left,
											   params);
			if (l) {
				rexp->params.pair.left = l;
				return rexp;
			} else {
				rexp->params.pair.left = 0;
				rx_free_rexp(rx, rexp);
				return 0;
			}
		case r_side_effect:
		{
			int se = (long) rexp->params.side_effect;

			if ((se >= 0)
				&& (((enum re_side_effects) params[se].se == re_se_lparen)
					|| ((enum re_side_effects) params[se].se ==
						re_se_rparen)) && (params[se].op1 > 0)
				&& (!needed[params[se].op1])) {
				rx_free_rexp(rx, rexp);
				return 0;
			} else
				return rexp;
		}
		}

	/* this should never happen */
	return 0;
}



#ifdef __STDC__
static int
pointless_if_repeated(struct rexp_node *node, struct re_se_params *params)
#else
static int pointless_if_repeated(node, params)
struct rexp_node *node;
struct re_se_params *params;
#endif
{
	if (!node)
		return 1;
	switch (node->type) {
	case r_cset:
		return 0;
	case r_alternate:
	case r_concat:
	case r_2phase_star:
		return (pointless_if_repeated(node->params.pair.left, params)
				&& pointless_if_repeated(node->params.pair.right, params));
	case r_opt:
	case r_star:
		return pointless_if_repeated(node->params.pair.left, params);
	case r_side_effect:
		switch (((long) node->params.side_effect < 0)
				? (enum re_side_effects) node->params.side_effect
				: (enum re_side_effects) params[(long) node->
												params.side_effect].se) {
		case re_se_try:
		case re_se_at_dot:
		case re_se_begbuf:
		case re_se_hat:
		case re_se_wordbeg:
		case re_se_wordbound:
		case re_se_notwordbound:
		case re_se_wordend:
		case re_se_endbuf:
		case re_se_dollar:
		case re_se_fail:
		case re_se_win:
			return 1;
		case re_se_lparen:
		case re_se_rparen:
		case re_se_iter:
		case re_se_end_iter:
		case re_se_syntax:
		case re_se_not_syntax:
		case re_se_backref:
			return 0;
		}
	case r_data:
	default:
		return 0;
	}
}



#ifdef __STDC__
static int
registers_on_stack(struct re_pattern_buffer *rxb,
				   struct rexp_node *rexp, int in_danger,
				   struct re_se_params *params)
#else
static int registers_on_stack(rxb, rexp, in_danger, params)
struct re_pattern_buffer *rxb;
struct rexp_node *rexp;
int in_danger;
struct re_se_params *params;
#endif
{
	if (!rexp)
		return 0;
	else
		switch (rexp->type) {
		case r_cset:
		case r_data:
			return 0;
		case r_alternate:
		case r_concat:
			return (registers_on_stack(rxb, rexp->params.pair.left,
									   in_danger, params)
					|| (registers_on_stack
						(rxb, rexp->params.pair.right,
						 in_danger, params)));
		case r_opt:
			return registers_on_stack(rxb, rexp->params.pair.left, 0,
									  params);
		case r_star:
			return registers_on_stack(rxb, rexp->params.pair.left, 1,
									  params);
		case r_2phase_star:
			return
				(registers_on_stack(rxb, rexp->params.pair.left, 1, params)
				 || registers_on_stack(rxb, rexp->params.pair.right, 1,
									   params));
		case r_side_effect:
		{
			int se = (long) rexp->params.side_effect;

			if (in_danger && (se >= 0)
				&& (params[se].op1 > 0)
				&& (((enum re_side_effects) params[se].se == re_se_lparen)
					|| ((enum re_side_effects) params[se].se ==
						re_se_rparen))) return 1;
			else
				return 0;
		}
		}

	/* this should never happen */
	return 0;
}



static char idempotent_complex_se[] = {
#define RX_WANT_SE_DEFS 1
#undef RX_DEF_SE
#undef RX_DEF_CPLX_SE
#define RX_DEF_SE(IDEM, NAME, VALUE)
#define RX_DEF_CPLX_SE(IDEM, NAME, VALUE)     IDEM,
#include <regex.h>
#undef RX_DEF_SE
#undef RX_DEF_CPLX_SE
#undef RX_WANT_SE_DEFS
	23
};

static char idempotent_se[] = {
	13,
#define RX_WANT_SE_DEFS 1
#undef RX_DEF_SE
#undef RX_DEF_CPLX_SE
#define RX_DEF_SE(IDEM, NAME, VALUE)	      IDEM,
#define RX_DEF_CPLX_SE(IDEM, NAME, VALUE)
#include <regex.h>
#undef RX_DEF_SE
#undef RX_DEF_CPLX_SE
#undef RX_WANT_SE_DEFS
	42
};



#ifdef __STDC__
static int has_any_se(struct rx *rx, struct rexp_node *rexp)
#else
static int has_any_se(rx, rexp)
struct rx *rx;
struct rexp_node *rexp;
#endif
{
	if (!rexp)
		return 0;

	switch (rexp->type) {
	case r_cset:
	case r_data:
		return 0;

	case r_side_effect:
		return 1;

	case r_2phase_star:
	case r_concat:
	case r_alternate:
		return (has_any_se(rx, rexp->params.pair.left)
				|| has_any_se(rx, rexp->params.pair.right));

	case r_opt:
	case r_star:
		return has_any_se(rx, rexp->params.pair.left);
	}

	/* this should never happen */
	return 0;
}



/* This must be called AFTER `convert_hard_loops' for a given REXP. */
#ifdef __STDC__
static int
has_non_idempotent_epsilon_path(struct rx *rx,
								struct rexp_node *rexp,
								struct re_se_params *params)
#else
static int has_non_idempotent_epsilon_path(rx, rexp, params)
struct rx *rx;
struct rexp_node *rexp;
struct re_se_params *params;
#endif
{
	if (!rexp)
		return 0;

	switch (rexp->type) {
	case r_cset:
	case r_data:
	case r_star:
		return 0;

	case r_side_effect:
		return
			!((long) rexp->params.side_effect > 0
			  ?
			  idempotent_complex_se[params
									[(long) rexp->params.
									 side_effect].se] :
			  idempotent_se[-(long) rexp->params.side_effect]);

	case r_alternate:
		return
			(has_non_idempotent_epsilon_path(rx,
											 rexp->params.pair.left,
											 params)
			 || has_non_idempotent_epsilon_path(rx,
												rexp->params.pair.right,
												params));

	case r_2phase_star:
	case r_concat:
		return
			(has_non_idempotent_epsilon_path(rx,
											 rexp->params.pair.left,
											 params)
			 && has_non_idempotent_epsilon_path(rx,
												rexp->params.pair.right,
												params));

	case r_opt:
		return has_non_idempotent_epsilon_path(rx,
											   rexp->params.pair.left,
											   params);
	}

	/* this should never happen */
	return 0;
}



/* This computes rougly what it's name suggests.   It can (and does) go wrong 
 * in the direction of returning spurious 0 without causing disasters.
 */
#ifdef __STDC__
static int begins_with_complex_se(struct rx *rx, struct rexp_node *rexp)
#else
static int begins_with_complex_se(rx, rexp)
struct rx *rx;
struct rexp_node *rexp;
#endif
{
	if (!rexp)
		return 0;

	switch (rexp->type) {
	case r_cset:
	case r_data:
		return 0;

	case r_side_effect:
		return ((long) rexp->params.side_effect >= 0);

	case r_alternate:
		return (begins_with_complex_se(rx, rexp->params.pair.left)
				&& begins_with_complex_se(rx, rexp->params.pair.right));


	case r_concat:
		return has_any_se(rx, rexp->params.pair.left);
	case r_opt:
	case r_star:
	case r_2phase_star:
		return 0;
	}

	/* this should never happen */
	return 0;
}


/* This destructively removes some of the re_se_tv side effects from 
 * a rexp tree.  In particular, during parsing re_se_tv was inserted on the
 * right half of every | to guarantee that posix path preference could be 
 * honored.  This function removes some which it can be determined aren't 
 * needed.  
 */

#ifdef __STDC__
static void
speed_up_alt(struct rx *rx, struct rexp_node *rexp, int unposix)
#else
static void speed_up_alt(rx, rexp, unposix)
struct rx *rx;
struct rexp_node *rexp;
int unposix;
#endif
{
	if (!rexp)
		return;

	switch (rexp->type) {
	case r_cset:
	case r_data:
	case r_side_effect:
		return;

	case r_opt:
	case r_star:
		speed_up_alt(rx, rexp->params.pair.left, unposix);
		return;

	case r_2phase_star:
	case r_concat:
		speed_up_alt(rx, rexp->params.pair.left, unposix);
		speed_up_alt(rx, rexp->params.pair.right, unposix);
		return;

	case r_alternate:
		/* the right child is guaranteed to be (concat re_se_tv <subexp>) */

		speed_up_alt(rx, rexp->params.pair.left, unposix);
		speed_up_alt(rx, rexp->params.pair.right->params.pair.right,
					 unposix);

		if (unposix
			|| (begins_with_complex_se
				(rx, rexp->params.pair.right->params.pair.right))
			|| !(has_any_se(rx, rexp->params.pair.right->params.pair.right)
				 || has_any_se(rx, rexp->params.pair.left))) {
			struct rexp_node *conc = rexp->params.pair.right;

			rexp->params.pair.right = conc->params.pair.right;
			conc->params.pair.right = 0;
			rx_free_rexp(rx, conc);
		}
	}
}





/* `regex_compile' compiles PATTERN (of length SIZE) according to SYNTAX.
   Returns one of error codes defined in `regex.h', or zero for success.

   Assumes the `allocated' (and perhaps `buffer') and `translate'
   fields are set in BUFP on entry.

   If it succeeds, results are put in BUFP (if it returns an error, the
   contents of BUFP are undefined):
     `buffer' is the compiled pattern;
     `syntax' is set to SYNTAX;
     `used' is set to the length of the compiled pattern;
     `fastmap_accurate' is set to zero;
     `re_nsub' is set to the number of groups in PATTERN;
     `not_bol' and `not_eol' are set to zero.
   
   The `fastmap' and `newline_anchor' fields are neither
   examined nor set.  */


#ifdef __STDC__
RX_DECL reg_errcode_t
rx_compile(__const__ char *pattern, int size,
		   reg_syntax_t syntax, struct re_pattern_buffer *rxb)
#else
RX_DECL reg_errcode_t rx_compile(pattern, size, syntax, rxb)
__const__ char *pattern;
int size;
reg_syntax_t syntax;
struct re_pattern_buffer *rxb;
#endif
{
	RX_subset
		inverse_translate[CHAR_SET_SIZE *
						  rx_bitset_numb_subsets(CHAR_SET_SIZE)];
	char validate_inv_tr[CHAR_SET_SIZE *

						 rx_bitset_numb_subsets(CHAR_SET_SIZE)];

	/* We fetch characters from PATTERN here.  Even though PATTERN is
	   `char *' (i.e., signed), we declare these variables as unsigned, so
	   they can be reliably used as array indices.  */
	register unsigned char c, c1;

	/* A random tempory spot in PATTERN.  */
	__const__ char *p1;

	/* Keeps track of unclosed groups.  */
	compile_stack_type compile_stack;

	/* Points to the current (ending) position in the pattern.  */
	__const__ char *p = pattern;
	__const__ char *pend = pattern + size;

	/* How to translate the characters in the pattern.  */
	unsigned char *translate = (rxb->translate

								? rxb->translate : rx_id_translation);

	/* When parsing is done, this will hold the expression tree. */
	struct rexp_node *rexp = 0;

	/* In the midst of compilation, this holds onto the regexp 
	 * first parst while rexp goes on to aquire additional constructs.
	 */
	struct rexp_node *orig_rexp = 0;
	struct rexp_node *fewer_side_effects = 0;

	/* This and top_expression are saved on the compile stack. */
	struct rexp_node **top_expression = &rexp;
	struct rexp_node **last_expression = top_expression;

	/* Parameter to `goto append_node' */
	struct rexp_node *append;

	/* Counts open-groups as they are encountered.  This is the index of the
	 * innermost group being compiled.
	 */
	regnum_t regnum = 0;

	/* Place in the uncompiled pattern (i.e., the {) to
	 * which to go back if the interval is invalid.  
	 */
	__const__ char *beg_interval;

	struct re_se_params *params = 0;
	int paramc = 0;				/* How many complex side effects so far? */

	rx_side_effect side;		/* param to `goto add_side_effect' */

	bzero(validate_inv_tr, sizeof(validate_inv_tr));

	rxb->rx.instruction_table = rx_id_instruction_table;


	/* Initialize the compile stack.  */
	compile_stack.stack = ((compile_stack_elt_t *)
						   malloc((INIT_COMPILE_STACK_SIZE) *
								  sizeof(compile_stack_elt_t)));
	if (compile_stack.stack == 0)
		return REG_ESPACE;

	compile_stack.size = INIT_COMPILE_STACK_SIZE;
	compile_stack.avail = 0;

	/* Initialize the pattern buffer.  */
	rxb->rx.cache = &default_cache;
	rxb->syntax = syntax;
	rxb->fastmap_accurate = 0;
	rxb->not_bol = rxb->not_eol = 0;
	rxb->least_subs = 0;

	/* Always count groups, whether or not rxb->no_sub is set.  
	 * The whole pattern is implicitly group 0, so counting begins
	 * with 1.
	 */
	rxb->re_nsub = 0;

#if !defined (emacs) && !defined (SYNTAX_TABLE)
	/* Initialize the syntax table.  */
	init_syntax_once();
#endif

	/* Loop through the uncompiled pattern until we're at the end.  */
	while (p != pend) {
		PATFETCH(c);

		switch (c) {
		case '^':
		{
			if (				/* If at start of pattern, it's an operator.  */
				   p == pattern + 1
				   /* If context independent, it's an operator.  */
				   || syntax & RE_CONTEXT_INDEP_ANCHORS
				   /* Otherwise, depends on what's come before.  */
				   || at_begline_loc_p(pattern, p, syntax)) {
				struct rexp_node *n = rx_mk_r_side_effect(&rxb->rx,
														  (rx_side_effect) re_se_hat);

				if (!n)
					return REG_ESPACE;
				append = n;
				goto append_node;
			} else
				goto normal_char;
		}
			break;


		case '$':
		{
			if (				/* If at end of pattern, it's an operator.  */
				   p == pend
				   /* If context independent, it's an operator.  */
				   || syntax & RE_CONTEXT_INDEP_ANCHORS
				   /* Otherwise, depends on what's next.  */
				   || at_endline_loc_p(p, pend, syntax)) {
				struct rexp_node *n = rx_mk_r_side_effect(&rxb->rx,
														  (rx_side_effect) re_se_dollar);

				if (!n)
					return REG_ESPACE;
				append = n;
				goto append_node;
			} else
				goto normal_char;
		}
			break;


		case '+':
		case '?':
			if ((syntax & RE_BK_PLUS_QM)
				|| (syntax & RE_LIMITED_OPS))
				goto normal_char;

		  handle_plus:
		case '*':
			/* If there is no previous pattern... */
			if (pointless_if_repeated(*last_expression, params)) {
				if (syntax & RE_CONTEXT_INVALID_OPS)
					return REG_BADRPT;
				else if (!(syntax & RE_CONTEXT_INDEP_OPS))
					goto normal_char;
			}

			{
				/* 1 means zero (many) matches is allowed.  */
				char zero_times_ok = 0, many_times_ok = 0;

				/* If there is a sequence of repetition chars, collapse it
				   down to just one (the right one).  We can't combine
				   interval operators with these because of, e.g., `a{2}*',
				   which should only match an even number of `a's.  */

				for (;;) {
					zero_times_ok |= c != '+';
					many_times_ok |= c != '?';

					if (p == pend)
						break;

					PATFETCH(c);

					if (c == '*' || (!(syntax & RE_BK_PLUS_QM)
									 && (c == '+' || c == '?')));

					else if (syntax & RE_BK_PLUS_QM && c == '\\') {
						if (p == pend)
							return REG_EESCAPE;

						PATFETCH(c1);
						if (!(c1 == '+' || c1 == '?')) {
							PATUNFETCH;
							PATUNFETCH;
							break;
						}

						c = c1;
					} else {
						PATUNFETCH;
						break;
					}

					/* If we get here, we found another repeat character.  */
				}

				/* Star, etc. applied to an empty pattern is equivalent
				   to an empty pattern.  */
				if (!last_expression)
					break;

				/* Now we know whether or not zero matches is allowed
				 * and also whether or not two or more matches is allowed.
				 */

				{
					struct rexp_node *inner_exp = *last_expression;
					int need_sync = 0;

					if (many_times_ok
						&& has_non_idempotent_epsilon_path(&rxb->rx,
														   inner_exp,
														   params)) {
						struct rexp_node *pusher =
							rx_mk_r_side_effect(&rxb->rx,
												(rx_side_effect) re_se_pushpos);
						struct rexp_node *checker
							= rx_mk_r_side_effect(&rxb->rx,
												  (rx_side_effect) re_se_chkpos);
						struct rexp_node *pushback
							= rx_mk_r_side_effect(&rxb->rx,
												  (rx_side_effect) re_se_pushback);
						rx_Bitset cs = rx_cset(&rxb->rx);
						struct rexp_node *lit_t;
						struct rexp_node *fake_state;
						struct rexp_node *phase2;
						struct rexp_node *popper;
						struct rexp_node *star;
						struct rexp_node *a;
						struct rexp_node *whole_thing;

						if (!cs)
							return REG_ESPACE;
						lit_t = rx_mk_r_cset(&rxb->rx, cs);
						fake_state =
							rx_mk_r_concat(&rxb->rx, pushback, lit_t);
						phase2 =
							rx_mk_r_concat(&rxb->rx, checker, fake_state);
						popper =
							rx_mk_r_side_effect(&rxb->rx,
												(rx_side_effect)
												re_se_poppos);
						star =
							rx_mk_r_2phase_star(&rxb->rx, inner_exp,
												phase2);
						a = rx_mk_r_concat(&rxb->rx, pusher, star);
						whole_thing = rx_mk_r_concat(&rxb->rx, a, popper);

						if (!
							(pusher && star && pushback && lit_t
							 && fake_state && lit_t && phase2 && checker
							 && popper && a && whole_thing))
							return REG_ESPACE;
						RX_bitset_enjoin(cs, 't');
						*last_expression = whole_thing;
					} else {
						struct rexp_node *star =
							(many_times_ok ? rx_mk_r_star : rx_mk_r_opt)
							(&rxb->rx, *last_expression);

						if (!star)
							return REG_ESPACE;
						*last_expression = star;
						need_sync = has_any_se(&rxb->rx, *last_expression);
					}
					if (!zero_times_ok) {
						struct rexp_node *concat
							= rx_mk_r_concat(&rxb->rx, inner_exp,
											 rx_copy_rexp(&rxb->rx,
														  *last_expression));

						if (!concat)
							return REG_ESPACE;
						*last_expression = concat;
					}
					if (need_sync) {
						int sync_se = paramc;

						params = (params ? ((struct re_se_params *)
											realloc(params,
													sizeof(*params) * (1 +
																	   paramc)))
								  : ((struct re_se_params *)
									 malloc(sizeof(*params))));
						if (!params)
							return REG_ESPACE;
						++paramc;
						params[sync_se].se = re_se_tv;
						side = (rx_side_effect) sync_se;
						goto add_side_effect;
					}
				}
				/* The old regex.c used to optimize `.*\n'.  
				 * Maybe rx should too?
				 */
			}
			break;


		case '.':
		{
			rx_Bitset cs = rx_cset(&rxb->rx);
			struct rexp_node *n = rx_mk_r_cset(&rxb->rx, cs);

			if (!(cs && n))
				return REG_ESPACE;

			rx_bitset_universe(rxb->rx.local_cset_size, cs);
			if (!(rxb->syntax & RE_DOT_NEWLINE))
				RX_bitset_remove(cs, '\n');
			if (!(rxb->syntax & RE_DOT_NOT_NULL))
				RX_bitset_remove(cs, 0);

			append = n;
			goto append_node;
			break;
		}


		case '[':
			if (p == pend)
				return REG_EBRACK;
			{
				boolean had_char_class = false;
				rx_Bitset cs = rx_cset(&rxb->rx);
				struct rexp_node *node = rx_mk_r_cset(&rxb->rx, cs);
				int is_inverted = *p == '^';

				if (!(node && cs))
					return REG_ESPACE;

				/* This branch of the switch is normally exited with
				 *`goto append_node'
				 */
				append = node;

				if (is_inverted)
					p++;

				/* Remember the first position in the bracket expression.  */
				p1 = p;

				/* Read in characters and ranges, setting map bits.  */
				for (;;) {
					if (p == pend)
						return REG_EBRACK;

					PATFETCH(c);

					/* \ might escape characters inside [...] and [^...].  */
					if ((syntax & RE_BACKSLASH_ESCAPE_IN_LISTS)
						&& c == '\\') {
						if (p == pend)
							return REG_EESCAPE;

						PATFETCH(c1);
						{
							rx_Bitset it = inverse_translation(rxb,
															   validate_inv_tr,
															   inverse_translate,
															   translate,
															   c1);

							rx_bitset_union(rxb->rx.local_cset_size, cs,
											it);
						}
						continue;
					}

					/* Could be the end of the bracket expression.  If it's
					   not (i.e., when the bracket expression is `[]' so
					   far), the ']' character bit gets set way below.  */
					if (c == ']' && p != p1 + 1)
						goto finalize_class_and_append;

					/* Look ahead to see if it's a range when the last thing
					   was a character class.  */
					if (had_char_class && c == '-' && *p != ']')
						return REG_ERANGE;

					/* Look ahead to see if it's a range when the last thing
					   was a character: if this is a hyphen not at the
					   beginning or the end of a list, then it's the range
					   operator.  */
					if (c == '-' && !(p - 2 >= pattern && p[-2] == '[')
						&& !(p - 3 >= pattern && p[-3] == '['
							 && p[-2] == '^') && *p != ']') {
						reg_errcode_t ret =
							compile_range(rxb, cs, &p, pend, translate,
										  syntax,
										  inverse_translate,

										  validate_inv_tr);

						if (ret != REG_NOERROR)
							return ret;
					}

					else if (p[0] == '-' && p[1] != ']') {	/* This handles ranges made up of characters only.  */
						reg_errcode_t ret;

						/* Move past the `-'.  */
						PATFETCH(c1);

						ret =
							compile_range(rxb, cs, &p, pend, translate,
										  syntax, inverse_translate,
										  validate_inv_tr);
						if (ret != REG_NOERROR)
							return ret;
					}

					/* See if we're at the beginning of a possible character
					   class.  */

					else if ((syntax & RE_CHAR_CLASSES)
							 && (c == '[') && (*p == ':')) {
						char str[CHAR_CLASS_MAX_LENGTH + 1];

						PATFETCH(c);
						c1 = 0;

						/* If pattern is `[[:'.  */
						if (p == pend)
							return REG_EBRACK;

						for (;;) {
							PATFETCH(c);
							if (c == ':' || c == ']' || p == pend
								|| c1 == CHAR_CLASS_MAX_LENGTH) break;
							str[c1++] = c;
						}
						str[c1] = '\0';

						/* If isn't a word bracketed by `[:' and:`]':
						   undo the ending character, the letters, and leave 
						   the leading `:' and `[' (but set bits for them).  */
						if (c == ':' && *p == ']') {
							int ch;
							boolean is_alnum = !strcmp(str, "alnum");
							boolean is_alpha = !strcmp(str, "alpha");
							boolean is_blank = !strcmp(str, "blank");
							boolean is_cntrl = !strcmp(str, "cntrl");
							boolean is_digit = !strcmp(str, "digit");
							boolean is_graph = !strcmp(str, "graph");
							boolean is_lower = !strcmp(str, "lower");
							boolean is_print = !strcmp(str, "print");
							boolean is_punct = !strcmp(str, "punct");
							boolean is_space = !strcmp(str, "space");
							boolean is_upper = !strcmp(str, "upper");
							boolean is_xdigit = !strcmp(str, "xdigit");

							if (!IS_CHAR_CLASS(str))
								return REG_ECTYPE;

							/* Throw away the ] at the end of the character
							   class.  */
							PATFETCH(c);

							if (p == pend)
								return REG_EBRACK;

							for (ch = 0; ch < 1 << CHARBITS; ch++) {
								if ((is_alnum && isalnum(ch))
									|| (is_alpha && isalpha(ch))
									|| (is_blank && isblank(ch))
									|| (is_cntrl && iscntrl(ch))
									|| (is_digit && isdigit(ch))
									|| (is_graph && isgraph(ch))
									|| (is_lower && islower(ch))
									|| (is_print && isprint(ch))
									|| (is_punct && ispunct(ch))
									|| (is_space && isspace(ch))
									|| (is_upper && isupper(ch))
									|| (is_xdigit && isxdigit(ch))) {
									rx_Bitset it = inverse_translation(rxb,
																	   validate_inv_tr,
																	   inverse_translate,
																	   translate,
																	   ch);

									rx_bitset_union(rxb->
													rx.local_cset_size, cs,
													it);
								}
							}
							had_char_class = true;
						} else {
							c1++;
							while (c1--)
								PATUNFETCH;
							{
								rx_Bitset it = inverse_translation(rxb,
																   validate_inv_tr,
																   inverse_translate,
																   translate,
																   '[');

								rx_bitset_union(rxb->rx.local_cset_size,
												cs, it);
							}
							{
								rx_Bitset it = inverse_translation(rxb,
																   validate_inv_tr,
																   inverse_translate,
																   translate,
																   ':');

								rx_bitset_union(rxb->rx.local_cset_size,
												cs, it);
							}
							had_char_class = false;
						}
					} else {
						had_char_class = false;
						{
							rx_Bitset it = inverse_translation(rxb,
															   validate_inv_tr,
															   inverse_translate,
															   translate,
															   c);

							rx_bitset_union(rxb->rx.local_cset_size, cs,
											it);
						}
					}
				}

			  finalize_class_and_append:
				if (is_inverted) {
					rx_bitset_complement(rxb->rx.local_cset_size, cs);
					if (syntax & RE_HAT_LISTS_NOT_NEWLINE)
						RX_bitset_remove(cs, '\n');
				}
				goto append_node;
			}
			break;


		case '(':
			if (syntax & RE_NO_BK_PARENS)
				goto handle_open;
			else
				goto normal_char;


		case ')':
			if (syntax & RE_NO_BK_PARENS)
				goto handle_close;
			else
				goto normal_char;


		case '\n':
			if (syntax & RE_NEWLINE_ALT)
				goto handle_alt;
			else
				goto normal_char;


		case '|':
			if (syntax & RE_NO_BK_VBAR)
				goto handle_alt;
			else
				goto normal_char;


		case '{':
			if ((syntax & RE_INTERVALS) && (syntax & RE_NO_BK_BRACES))
				goto handle_interval;
			else
				goto normal_char;


		case '\\':
			if (p == pend)
				return REG_EESCAPE;

			/* Do not translate the character after the \, so that we can
			   distinguish, e.g., \B from \b, even if we normally would
			   translate, e.g., B to b.  */
			PATFETCH_RAW(c);

			switch (c) {
			case '(':
				if (syntax & RE_NO_BK_PARENS)
					goto normal_backslash;

			  handle_open:
				rxb->re_nsub++;
				regnum++;
				if (COMPILE_STACK_FULL) {
					((compile_stack.stack) =
					 (compile_stack_elt_t *) realloc(compile_stack.stack,
													 (compile_stack.size <<
													  1) *
													 sizeof
													 (compile_stack_elt_t)));
					if (compile_stack.stack == 0)
						return REG_ESPACE;

					compile_stack.size <<= 1;
				}

				if (*last_expression) {
					struct rexp_node *concat
						= rx_mk_r_concat(&rxb->rx, *last_expression, 0);

					if (!concat)
						return REG_ESPACE;
					*last_expression = concat;
					last_expression = &concat->params.pair.right;
				}

				/*
				   * These are the values to restore when we hit end of this
				   * group.  
				 */
				COMPILE_STACK_TOP.top_expression = top_expression;
				COMPILE_STACK_TOP.last_expression = last_expression;
				COMPILE_STACK_TOP.regnum = regnum;

				compile_stack.avail++;

				top_expression = last_expression;
				break;


			case ')':
				if (syntax & RE_NO_BK_PARENS)
					goto normal_backslash;

			  handle_close:
				/* See similar code for backslashed left paren above.  */
				if (COMPILE_STACK_EMPTY) {
					if (syntax & RE_UNMATCHED_RIGHT_PAREN_ORD) {
						goto normal_char;
					} else {
						return REG_ERPAREN;
					}
				}

				/* Since we just checked for an empty stack above, this
				   ``can't happen''.  */

				{
					/* We don't just want to restore into `regnum', because
					   later groups should continue to be numbered higher,
					   as in `(ab)c(de)' -- the second group is #2.  */
					regnum_t this_group_regnum;
					struct rexp_node **inner = top_expression;

					compile_stack.avail--;
					top_expression = COMPILE_STACK_TOP.top_expression;
					last_expression = COMPILE_STACK_TOP.last_expression;
					this_group_regnum = COMPILE_STACK_TOP.regnum;
					{
						int left_se = paramc;
						int right_se = paramc + 1;

						params = (params ? ((struct re_se_params *)
											realloc(params,
													(paramc +
													 2) *
													sizeof(params[0])))
								  : ((struct re_se_params *)
									 malloc(2 * sizeof(params[0]))));
						if (!params)
							return REG_ESPACE;
						paramc += 2;

						params[left_se].se = re_se_lparen;
						params[left_se].op1 = this_group_regnum;
						params[right_se].se = re_se_rparen;
						params[right_se].op1 = this_group_regnum;
						{
							struct rexp_node *left
								= rx_mk_r_side_effect(&rxb->rx,
													  (rx_side_effect) left_se);
							struct rexp_node *right
								= rx_mk_r_side_effect(&rxb->rx,
													  (rx_side_effect) right_se);
							struct rexp_node *c1
								= (*inner ? rx_mk_r_concat(&rxb->rx, left,
														   *inner) : left);
							struct rexp_node *c2 =
								rx_mk_r_concat(&rxb->rx, c1, right);

							if (!(left && right && c1 && c2))
								return REG_ESPACE;
							*inner = c2;
						}
					}
					break;
				}

			case '|':			/* `\|'.  */
				if ((syntax & RE_LIMITED_OPS) || (syntax & RE_NO_BK_VBAR))
					goto normal_backslash;
			  handle_alt:
				if (syntax & RE_LIMITED_OPS)
					goto normal_char;

				{
					struct rexp_node *alt
						= rx_mk_r_alternate(&rxb->rx, *top_expression, 0);

					if (!alt)
						return REG_ESPACE;
					*top_expression = alt;
					last_expression = &alt->params.pair.right;
					{
						int sync_se = paramc;

						params = (params ? ((struct re_se_params *)
											realloc(params,
													(paramc +
													 1) *
													sizeof(params[0])))
								  : ((struct re_se_params *)
									 malloc(sizeof(params[0]))));
						if (!params)
							return REG_ESPACE;
						++paramc;

						params[sync_se].se = re_se_tv;
						{
							struct rexp_node *sync
								= rx_mk_r_side_effect(&rxb->rx,
													  (rx_side_effect) sync_se);
							struct rexp_node *conc
								= rx_mk_r_concat(&rxb->rx, sync, 0);

							if (!sync || !conc)
								return REG_ESPACE;

							*last_expression = conc;
							last_expression = &conc->params.pair.right;
						}
					}
				}
				break;


			case '{':
				/* If \{ is a literal.  */
				if (!(syntax & RE_INTERVALS)
					/* If we're at `\{' and it's not the open-interval 
					   operator.  */
					|| ((syntax & RE_INTERVALS)
						&& (syntax & RE_NO_BK_BRACES)) || (p - 2 == pattern
														   && p == pend))
					goto normal_backslash;

			  handle_interval:
				{
					/* If got here, then the syntax allows intervals.  */

					/* At least (most) this many matches must be made.  */
					int lower_bound = -1, upper_bound = -1;

					beg_interval = p - 1;

					if (p == pend) {
						if (syntax & RE_NO_BK_BRACES)
							goto unfetch_interval;
						else
							return REG_EBRACE;
					}

					GET_UNSIGNED_NUMBER(lower_bound);

					if (c == ',') {
						GET_UNSIGNED_NUMBER(upper_bound);
						if (upper_bound < 0)
							upper_bound = RE_DUP_MAX;
					} else
						/* Interval such as `{1}' => match exactly once. */
						upper_bound = lower_bound;

					if (lower_bound < 0 || upper_bound > RE_DUP_MAX
						|| lower_bound > upper_bound) {
						if (syntax & RE_NO_BK_BRACES)
							goto unfetch_interval;
						else
							return REG_BADBR;
					}

					if (!(syntax & RE_NO_BK_BRACES)) {
						if (c != '\\')
							return REG_EBRACE;
						PATFETCH(c);
					}

					if (c != '}') {
						if (syntax & RE_NO_BK_BRACES)
							goto unfetch_interval;
						else
							return REG_BADBR;
					}

					/* We just parsed a valid interval.  */

					/* If it's invalid to have no preceding re.  */
					if (pointless_if_repeated(*last_expression, params)) {
						if (syntax & RE_CONTEXT_INVALID_OPS)
							return REG_BADRPT;
						else if (!(syntax & RE_CONTEXT_INDEP_OPS))
							goto unfetch_interval;
						/* was: else laststart = b; */
					}

					/* If the upper bound is zero, don't want to iterate
					 * at all.
					 */
					if (upper_bound == 0) {
						if (*last_expression) {
							rx_free_rexp(&rxb->rx, *last_expression);
							*last_expression = 0;
						}
					} else
						/* Otherwise, we have a nontrivial interval. */
					{
						int iter_se = paramc;
						int end_se = paramc + 1;

						params = (params ? ((struct re_se_params *)
											realloc(params,
													sizeof(*params) * (2 +
																	   paramc)))
								  : ((struct re_se_params *)
									 malloc(2 * sizeof(*params))));
						if (!params)
							return REG_ESPACE;
						paramc += 2;
						params[iter_se].se = re_se_iter;
						params[iter_se].op1 = lower_bound;
						params[iter_se].op2 = upper_bound;

						params[end_se].se = re_se_end_iter;
						params[end_se].op1 = lower_bound;
						params[end_se].op2 = upper_bound;
						{
							struct rexp_node *push0
								= rx_mk_r_side_effect(&rxb->rx,
													  (rx_side_effect) re_se_push0);
							struct rexp_node *start_one_iter
								= rx_mk_r_side_effect(&rxb->rx,
													  (rx_side_effect) iter_se);
							struct rexp_node *phase1
								= rx_mk_r_concat(&rxb->rx, start_one_iter,
												 *last_expression);
							struct rexp_node *pushback
								= rx_mk_r_side_effect(&rxb->rx,
													  (rx_side_effect) re_se_pushback);
							rx_Bitset cs = rx_cset(&rxb->rx);
							struct rexp_node *lit_t;
							struct rexp_node *phase2;
							struct rexp_node *loop;
							struct rexp_node *push_n_loop;
							struct rexp_node *final_test;
							struct rexp_node *full_exp;

							if (!cs)
								return REG_ESPACE;
							lit_t = rx_mk_r_cset(&rxb->rx, cs);
							phase2 =
								rx_mk_r_concat(&rxb->rx, pushback, lit_t);
							loop =
								rx_mk_r_2phase_star(&rxb->rx, phase1,
													phase2);
							push_n_loop =
								rx_mk_r_concat(&rxb->rx, push0, loop);
							final_test =
								rx_mk_r_side_effect(&rxb->rx,
													(rx_side_effect)
													end_se);
							full_exp =
								rx_mk_r_concat(&rxb->rx, push_n_loop,
											   final_test);

							if (!(push0 && start_one_iter && phase1
								  && pushback && lit_t && phase2
								  && loop && push_n_loop && final_test
								  && full_exp)) return REG_ESPACE;

							RX_bitset_enjoin(cs, 't');

							*last_expression = full_exp;
						}
					}
					beg_interval = 0;
				}
				break;

			  unfetch_interval:
				/* If an invalid interval, match the characters as literals.  */
				p = beg_interval;
				beg_interval = 0;

				/* normal_char and normal_backslash need `c'.  */
				PATFETCH(c);

				if (!(syntax & RE_NO_BK_BRACES)) {
					if (p > pattern && p[-1] == '\\')
						goto normal_backslash;
				}
				goto normal_char;

#ifdef emacs
				/* There is no way to specify the before_dot and after_dot
				   operators.  rms says this is ok.  --karl  */
			case '=':
				side = (rx_side_effect) rx_se_at_dot;
				goto add_side_effect;
				break;

			case 's':
			case 'S':
			{
				rx_Bitset cs = rx_cset(&rxb->rx);
				struct rexp_node *set = rx_mk_r_cset(&rxb->rx, cs);

				if (!(cs && set))
					return REG_ESPACE;
				if (c == 'S')
					rx_bitset_universe(rxb->rx.local_cset_size, cs);

				PATFETCH(c);
				{
					int x;
					enum syntaxcode code = syntax_spec_code[c];

					for (x = 0; x < 256; ++x) {

						if (SYNTAX(x) == code) {
							rx_Bitset it =
								inverse_translation(rxb, validate_inv_tr,
													inverse_translate,
													translate, x);

							rx_bitset_xor(rxb->rx.local_cset_size, cs, it);
						}
					}
				}
				append = set;
				goto append_node;
			}
				break;
#endif							/* emacs */


			case 'w':
			case 'W':
				if (syntax & RE_NO_GNU_OPS)
					goto normal_char;
				{
					rx_Bitset cs = rx_cset(&rxb->rx);
					struct rexp_node *n =
						(cs ? rx_mk_r_cset(&rxb->rx, cs) : 0);

					if (!(cs && n))
						return REG_ESPACE;
					if (c == 'W')
						rx_bitset_universe(rxb->rx.local_cset_size, cs);
					{
						int x;

						for (x = rxb->rx.local_cset_size - 1; x > 0; --x)
							if (SYNTAX(x) & Sword)
								RX_bitset_toggle(cs, x);
					}
					append = n;
					goto append_node;
				}
				break;

/* With a little extra work, some of these side effects could be optimized
 * away (basicly by looking at what we already know about the surrounding
 * chars).  
 */
			case '<':
				if (syntax & RE_NO_GNU_OPS)
					goto normal_char;
				side = (rx_side_effect) re_se_wordbeg;
				goto add_side_effect;
				break;

			case '>':
				if (syntax & RE_NO_GNU_OPS)
					goto normal_char;
				side = (rx_side_effect) re_se_wordend;
				goto add_side_effect;
				break;

			case 'b':
				if (syntax & RE_NO_GNU_OPS)
					goto normal_char;
				side = (rx_side_effect) re_se_wordbound;
				goto add_side_effect;
				break;

			case 'B':
				if (syntax & RE_NO_GNU_OPS)
					goto normal_char;
				side = (rx_side_effect) re_se_notwordbound;
				goto add_side_effect;
				break;

			case '`':
				if (syntax & RE_NO_GNU_OPS)
					goto normal_char;
				side = (rx_side_effect) re_se_begbuf;
				goto add_side_effect;
				break;

			case '\'':
				if (syntax & RE_NO_GNU_OPS)
					goto normal_char;
				side = (rx_side_effect) re_se_endbuf;
				goto add_side_effect;
				break;

			  add_side_effect:
				{
					struct rexp_node *se

						= rx_mk_r_side_effect(&rxb->rx, side);
					if (!se)
						return REG_ESPACE;
					append = se;
					goto append_node;
				}
				break;

			case '1':
			case '2':
			case '3':
			case '4':
			case '5':
			case '6':
			case '7':
			case '8':
			case '9':
				if (syntax & RE_NO_BK_REFS)
					goto normal_char;

				c1 = c - '0';

				if (c1 > regnum)
					return REG_ESUBREG;

				/* Can't back reference to a subexpression if inside of it.  */
				if (group_in_compile_stack(compile_stack, c1))
					return REG_ESUBREG;

				{
					int backref_se = paramc;

					params = (params ? ((struct re_se_params *)
										realloc(params,
												sizeof(*params) * (1 +
																   paramc)))
							  : ((struct re_se_params *)
								 malloc(sizeof(*params))));
					if (!params)
						return REG_ESPACE;
					++paramc;
					params[backref_se].se = re_se_backref;
					params[backref_se].op1 = c1;
					side = (rx_side_effect) backref_se;
					goto add_side_effect;
				}
				break;

			case '+':
			case '?':
				if (syntax & RE_BK_PLUS_QM)
					goto handle_plus;
				else
					goto normal_backslash;

			default:
			  normal_backslash:
				/* You might think it would be useful for \ to mean
				   not to translate; but if we don't translate it
				   it will never match anything.  */
				c = TRANSLATE(c);
				goto normal_char;
			}
			break;


		default:
			/* Expects the character in `c'.  */
		  normal_char:
		{
			rx_Bitset cs = rx_cset(&rxb->rx);
			struct rexp_node *match = rx_mk_r_cset(&rxb->rx, cs);
			rx_Bitset it;

			if (!(cs && match))
				return REG_ESPACE;
			it = inverse_translation(rxb, validate_inv_tr,
									 inverse_translate, translate, c);
			rx_bitset_union(CHAR_SET_SIZE, cs, it);
			append = match;

		  append_node:
			/* This genericly appends the rexp APPEND to *LAST_EXPRESSION
			 * and then parses the next character normally.
			 */
			if (*last_expression) {
				struct rexp_node *concat
					= rx_mk_r_concat(&rxb->rx, *last_expression, append);

				if (!concat)
					return REG_ESPACE;
				*last_expression = concat;
				last_expression = &concat->params.pair.right;
			} else
				*last_expression = append;
		}
		}						/* switch (c) */
	}							/* while p != pend */


	{
		int win_se = paramc;

		params = (params ? ((struct re_se_params *)
							realloc(params,
									sizeof(*params) * (1 + paramc)))
				  : ((struct re_se_params *)
					 malloc(sizeof(*params))));
		if (!params)
			return REG_ESPACE;
		++paramc;
		params[win_se].se = re_se_win;
		{
			struct rexp_node *se
				= rx_mk_r_side_effect(&rxb->rx, (rx_side_effect) win_se);
			struct rexp_node *concat = rx_mk_r_concat(&rxb->rx, rexp, se);

			if (!(se && concat))
				return REG_ESPACE;
			rexp = concat;
		}
	}


	/* Through the pattern now.  */

	if (!COMPILE_STACK_EMPTY)
		return REG_EPAREN;

	free(compile_stack.stack);

	orig_rexp = rexp;
#ifdef RX_DEBUG
	if (rx_debug_compile) {
		dbug_rxb = rxb;
		fputs("\n\nCompiling ", stdout);
		fwrite(pattern, 1, size, stdout);
		fputs(":\n", stdout);
		rxb->se_params = params;
		print_rexp(&rxb->rx, orig_rexp, 2, re_seprint, stdout);
	}
#endif
	{
		rx_Bitset cs = rx_cset(&rxb->rx);
		rx_Bitset cs2 = rx_cset(&rxb->rx);
		char *se_map = (char *) alloca(paramc);
		struct rexp_node *new_rexp = 0;


		bzero(se_map, paramc);
		find_backrefs(se_map, rexp, params);
		fewer_side_effects =
			remove_unecessary_side_effects(&rxb->rx, se_map,
										   rx_copy_rexp(&rxb->rx, rexp),
										   params);

		speed_up_alt(&rxb->rx, rexp, 0);
		speed_up_alt(&rxb->rx, fewer_side_effects, 1);

		{
			char *syntax_parens = rxb->syntax_parens;

			if (syntax_parens == (char *) 0x1)
				rexp = remove_unecessary_side_effects
					(&rxb->rx, se_map, rexp, params);
			else if (syntax_parens) {
				int x;

				for (x = 0; x < paramc; ++x)
					if (((params[x].se == re_se_lparen)
						 || (params[x].se == re_se_rparen))
						&& (!syntax_parens[params[x].op1]))
						se_map[x] = 1;
				rexp = remove_unecessary_side_effects
					(&rxb->rx, se_map, rexp, params);
			}
		}

		/* At least one more optimization would be nice to have here but i ran out 
		 * of time.  The idea would be to delay side effects.  
		 * For examle, `(abc)' is the same thing as `abc()' except that the
		 * left paren is offset by 3 (which we know at compile time).
		 * (In this comment, write that second pattern `abc(:3:)' 
		 * where `(:3:' is a syntactic unit.)
		 *
		 * Trickier:  `(abc|defg)'  is the same as `(abc(:3:|defg(:4:))'
		 * (The paren nesting may be hard to follow -- that's an alternation
		 *  of `abc(:3:' and `defg(:4:' inside (purely syntactic) parens
		 *  followed by the closing paren from the original expression.)
		 *
		 * Neither the expression tree representation nor the the nfa make
		 * this very easy to write. :(
		 */

		/* What we compile is different than what the parser returns.
		 * Suppose the parser returns expression R.
		 * Let R' be R with unnecessary register assignments removed 
		 * (see REMOVE_UNECESSARY_SIDE_EFFECTS, above).
		 *
		 * What we will compile is the expression:
		 *
		 *    m{try}R{win}\|s{try}R'{win}
		 *
		 * {try} and {win} denote side effect epsilons (see EXPLORE_FUTURE).
		 * 
		 * When trying a match, we insert an `m' at the beginning of the 
		 * string if the user wants registers to be filled, `s' if not.
		 */
		new_rexp =
			rx_mk_r_alternate
			(&rxb->rx,
			 rx_mk_r_concat(&rxb->rx, rx_mk_r_cset(&rxb->rx, cs2), rexp),
			 rx_mk_r_concat(&rxb->rx,
							rx_mk_r_cset(&rxb->rx, cs),
							fewer_side_effects));

		if (!(new_rexp && cs && cs2))
			return REG_ESPACE;
		RX_bitset_enjoin(cs2, '\0');	/* prefixed to the rexp used for matching. */
		RX_bitset_enjoin(cs, '\1');	/* prefixed to the rexp used for searching. */
		rexp = new_rexp;
	}

#ifdef RX_DEBUG
	if (rx_debug_compile) {
		fputs("\n...which is compiled as:\n", stdout);
		print_rexp(&rxb->rx, rexp, 2, re_seprint, stdout);
	}
#endif
	{
		struct rx_nfa_state *start = 0;
		struct rx_nfa_state *end = 0;

		if (!rx_build_nfa(&rxb->rx, rexp, &start, &end))
			return REG_ESPACE;	/*  */
		else {
			void *mem = (void *) rxb->buffer;
			unsigned long size = rxb->allocated;
			int start_id;
			char *perm_mem;
			int iterator_size = paramc * sizeof(params[0]);

			end->is_final = 1;
			start->is_start = 1;
			rx_name_nfa_states(&rxb->rx);
			start_id = start->id;
#ifdef RX_DEBUG
			if (rx_debug_compile) {
				fputs("...giving the NFA: \n", stdout);
				dbug_rxb = rxb;
				print_nfa(&rxb->rx, rxb->rx.nfa_states, re_seprint,
						  stdout);
			}
#endif
			if (!rx_eclose_nfa(&rxb->rx))
				return REG_ESPACE;
			else {
				rx_delete_epsilon_transitions(&rxb->rx);

				/* For compatability reasons, we need to shove the
				 * compiled nfa into one chunk of malloced memory.
				 */
				rxb->rx.reserved = (sizeof(params[0]) * paramc
									+
									rx_sizeof_bitset(rxb->
													 rx.local_cset_size));
#ifdef RX_DEBUG
				if (rx_debug_compile) {
					dbug_rxb = rxb;
					fputs("...which cooks down (uncompactified) to: \n",
						  stdout);
					print_nfa(&rxb->rx, rxb->rx.nfa_states, re_seprint,
							  stdout);
				}
#endif
				if (!rx_compactify_nfa(&rxb->rx, &mem, &size))
					return REG_ESPACE;
				rxb->buffer = mem;
				rxb->allocated = size;
				rxb->rx.buffer = mem;
				rxb->rx.allocated = size;
				perm_mem = ((char *) rxb->rx.buffer
							+ rxb->rx.allocated - rxb->rx.reserved);
				rxb->se_params = ((struct re_se_params *) perm_mem);
				bcopy(params, rxb->se_params, iterator_size);
				perm_mem += iterator_size;
				rxb->fastset = (rx_Bitset) perm_mem;
				rxb->start = rx_id_to_nfa_state(&rxb->rx, start_id);
			}
			rx_bitset_null(rxb->rx.local_cset_size, rxb->fastset);
			rxb->can_match_empty = compute_fastset(rxb, orig_rexp);
			rxb->match_regs_on_stack =
				registers_on_stack(rxb, orig_rexp, 0, params);
			rxb->search_regs_on_stack =
				registers_on_stack(rxb, fewer_side_effects, 0, params);
			if (rxb->can_match_empty)
				rx_bitset_universe(rxb->rx.local_cset_size, rxb->fastset);
			rxb->is_anchored =
				is_anchored(orig_rexp, (rx_side_effect) re_se_hat);
			rxb->begbuf_only =
				is_anchored(orig_rexp, (rx_side_effect) re_se_begbuf);
		}
		rx_free_rexp(&rxb->rx, rexp);
		if (params)
			free(params);
#ifdef RX_DEBUG
		if (rx_debug_compile) {
			dbug_rxb = rxb;
			fputs("...which cooks down to: \n", stdout);
			print_nfa(&rxb->rx, rxb->rx.nfa_states, re_seprint, stdout);
		}
#endif
	}
	return REG_NOERROR;
}



/* This table gives an error message for each of the error codes listed
   in regex.h.  Obviously the order here has to be same as there.  */

__const__ char *rx_error_msg[] = { 0,	/* REG_NOERROR */
	"No match",					/* REG_NOMATCH */
	"Invalid regular expression",	/* REG_BADPAT */
	"Invalid collation character",	/* REG_ECOLLATE */
	"Invalid character class name",	/* REG_ECTYPE */
	"Trailing backslash",		/* REG_EESCAPE */
	"Invalid back reference",	/* REG_ESUBREG */
	"Unmatched [ or [^",		/* REG_EBRACK */
	"Unmatched ( or \\(",		/* REG_EPAREN */
	"Unmatched \\{",			/* REG_EBRACE */
	"Invalid content of \\{\\}",	/* REG_BADBR */
	"Invalid range end",		/* REG_ERANGE */
	"Memory exhausted",			/* REG_ESPACE */
	"Invalid preceding regular expression",	/* REG_BADRPT */
	"Premature end of regular expression",	/* REG_EEND */
	"Regular expression too big",	/* REG_ESIZE */
	"Unmatched ) or \\)",		/* REG_ERPAREN */
};




char rx_slowmap[256] = {
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
};

#ifdef __STDC__
RX_DECL void rx_blow_up_fastmap(struct re_pattern_buffer *rxb)
#else
RX_DECL void rx_blow_up_fastmap(rxb)
struct re_pattern_buffer *rxb;
#endif
{
	int x;

	for (x = 0; x < 256; ++x)	/* &&&& 3.6 % */
		rxb->fastmap[x] = !!RX_bitset_member(rxb->fastset, x);
	rxb->fastmap_accurate = 1;
}




#if !defined(REGEX_MALLOC) && !defined(__GNUC__)
#define RE_SEARCH_2_FN	inner_re_search_2
#define RE_S2_QUAL static
#else
#define RE_SEARCH_2_FN	re_search_2
#define RE_S2_QUAL
#endif

struct re_search_2_closure {
	__const__ char *string1;
	int size1;
	__const__ char *string2;
	int size2;
};

RE_S2_QUAL int
RE_SEARCH_2_FN(struct re_pattern_buffer *,
			   __const__ char *,
			   int, __const__ char *, int, int,

			   int, struct re_registers *, int);
int re_rx_search(struct re_pattern_buffer *, int,
				 int, int, int, rx_get_burst_fn,
				 rx_back_check_fn, rx_fetch_char_fn,
				 void *, struct re_registers *,

				 struct rx_search_state *, struct rx_search_state *);
#if !defined(REGEX_MALLOC) && !defined(__GNUC__)
int re_search_2(struct re_pattern_buffer *,
				__const__ char *, int,
				__const__ char *, int,

				int, int, struct re_registers *, int);
#endif
int re_search(struct re_pattern_buffer *,

			  __const__ char *, int, int, int, struct re_registers *);
int re_match_2(struct re_pattern_buffer *,
			   __const__ char *, int,
			   __const__ char *, int, int, struct re_registers *, int);
int re_match(struct re_pattern_buffer *,

			 __const__ char *, int, int, struct re_registers *);
reg_syntax_t re_set_syntax(reg_syntax_t);
void re_set_registers(struct re_pattern_buffer *,
					  struct re_registers *, unsigned,
					  regoff_t *, regoff_t *);
static int cplx_se_sublist_len(struct rx_se_list *);
static int posix_se_list_order(struct rx *, struct rx_se_list *,

							   struct rx_se_list *);
__const__ char
*re_compile_pattern(__const__ char *, int, struct re_pattern_buffer *);
int re_compile_fastmap(struct re_pattern_buffer *);
char *re_comp(__const__ char *);
int re_exec(__const__ char *);
int regcomp(regex_t *, __const__ char *, int);
int regexec(__const__ regex_t *,
			__const__ char *, size_t, regmatch_t pmatch[], int);
size_t regerror(int, __const__ regex_t *, char *, size_t);

#ifdef __STDC__
static __inline__ enum rx_get_burst_return
re_search_2_get_burst(struct rx_string_position *pos,
					  void *vclosure, int stop)
#else
static __inline__ enum rx_get_burst_return
re_search_2_get_burst(pos, vclosure, stop)
struct rx_string_position *pos;
void *vclosure;
int stop;
#endif
{
	struct re_search_2_closure *closure;

	closure = (struct re_search_2_closure *) vclosure;
	if (!closure->string2) {
		int inset;

		inset = pos->pos - pos->string;
		if ((inset < -1) || (inset > closure->size1))
			return rx_get_burst_no_more;
		else {
			pos->pos =
				(__const__ unsigned char *) closure->string1 + inset;
			pos->string = (__const__ unsigned char *) closure->string1;
			pos->size = closure->size1;
			pos->end = ((__const__ unsigned char *)
						MIN(closure->string1 + closure->size1,
							closure->string1 + stop));
			pos->offset = 0;
			return ((pos->pos < pos->end)
					? rx_get_burst_ok : rx_get_burst_no_more);
		}
	} else if (!closure->string1) {
		int inset;

		inset = pos->pos - pos->string;
		pos->pos = (__const__ unsigned char *) closure->string2 + inset;
		pos->string = (__const__ unsigned char *) closure->string2;
		pos->size = closure->size2;
		pos->end = ((__const__ unsigned char *)
					MIN(closure->string2 + closure->size2,
						closure->string2 + stop));
		pos->offset = 0;
		return ((pos->pos < pos->end)
				? rx_get_burst_ok : rx_get_burst_no_more);
	} else {
		int inset;

		inset = pos->pos - pos->string + pos->offset;
		if (inset < closure->size1) {
			pos->pos =
				(__const__ unsigned char *) closure->string1 + inset;
			pos->string = (__const__ unsigned char *) closure->string1;
			pos->size = closure->size1;
			pos->end = ((__const__ unsigned char *)
						MIN(closure->string1 + closure->size1,
							closure->string1 + stop));
			pos->offset = 0;
			return rx_get_burst_ok;
		} else {
			pos->pos = ((__const__ unsigned char *)
						closure->string2 + inset - closure->size1);
			pos->string = (__const__ unsigned char *) closure->string2;
			pos->size = closure->size2;
			pos->end = ((__const__ unsigned char *)
						MIN(closure->string2 + closure->size2,
							closure->string2 + stop - closure->size1));
			pos->offset = closure->size1;
			return ((pos->pos < pos->end)
					? rx_get_burst_ok : rx_get_burst_no_more);
		}
	}
}


#ifdef __STDC__
static __inline__ enum rx_back_check_return
re_search_2_back_check(struct rx_string_position *pos,
					   int lparen, int rparen, unsigned char *translate,
					   void *vclosure, int stop)
#else
static __inline__ enum rx_back_check_return
re_search_2_back_check(pos, lparen, rparen, translate, vclosure, stop)
struct rx_string_position *pos;
int lparen;
int rparen;
unsigned char *translate;
void *vclosure;
int stop;
#endif
{
	struct rx_string_position there;
	struct rx_string_position past;

	there = *pos;
	there.pos = there.string + lparen - there.offset;
	re_search_2_get_burst(&there, vclosure, stop);

	past = *pos;
	past.pos = past.string + rparen - there.offset;
	re_search_2_get_burst(&past, vclosure, stop);

	++pos->pos;
	re_search_2_get_burst(pos, vclosure, stop);

	while ((there.pos != past.pos)
		   && (pos->pos != pos->end))
		if (TRANSLATE(*there.pos) != TRANSLATE(*pos->pos))
			return rx_back_check_fail;
		else {
			++there.pos;
			++pos->pos;
			if (there.pos == there.end)
				re_search_2_get_burst(&there, vclosure, stop);
			if (pos->pos == pos->end)
				re_search_2_get_burst(pos, vclosure, stop);
		}

	if (there.pos != past.pos)
		return rx_back_check_fail;
	--pos->pos;
	re_search_2_get_burst(pos, vclosure, stop);
	return rx_back_check_pass;
}

#ifdef __STDC__
static __inline__ int
re_search_2_fetch_char(struct rx_string_position *pos, int offset,
					   void *app_closure, int stop)
#else
static __inline__ int
re_search_2_fetch_char(pos, offset, app_closure, stop)
struct rx_string_position *pos;
int offset;
void *app_closure;
int stop;
#endif
{
	struct re_search_2_closure *closure;

	closure = (struct re_search_2_closure *) app_closure;
	if (offset == 0) {
		if (pos->pos >= pos->string)
			return *pos->pos;
		else {
			if (
				(pos->string ==
				 (__const__ unsigned char *) closure->string2)
				&& (closure->string1) && (closure->size1))
				return closure->string1[closure->size1 - 1];
			else
				return 0;		/* sure, why not. */
		}
	}
	if (pos->pos == pos->end)
		return *closure->string2;
	else
#if 0
		return pos->pos[1];
#else
		return pos->pos[offset];	/* FIXME */
#endif
}

#ifdef __STDC__
RE_S2_QUAL int
RE_SEARCH_2_FN(struct re_pattern_buffer *rxb,
			   __const__ char *string1, int size1,
			   __const__ char *string2, int size2,
			   int startpos, int range,
			   struct re_registers *regs, int stop)
#else
RE_S2_QUAL int
RE_SEARCH_2_FN(rxb,
			   string1, size1, string2, size2, startpos, range, regs, stop)
struct re_pattern_buffer *rxb;
__const__ char *string1;
int size1;
__const__ char *string2;
int size2;
int startpos;
int range;
struct re_registers *regs;
int stop;
#endif
{
	int answer;
	struct re_search_2_closure closure;

	closure.string1 = string1;
	closure.size1 = size1;
	closure.string2 = string2;
	closure.size2 = size2;
	answer = rx_search(rxb, startpos, range, stop, size1 + size2,
					   re_search_2_get_burst,
					   re_search_2_back_check,
					   re_search_2_fetch_char,
					   (void *) &closure, regs, 0, 0);
	switch (answer) {
	case rx_search_continuation:
		abort();
	case rx_search_error:
		return -2;
	case rx_search_soft_fail:
	case rx_search_fail:
		return -1;
	default:
		return answer;
	}
}

/* Export rx_search to callers outside this file.  */

#ifdef __STDC__
int
re_rx_search(struct re_pattern_buffer *rxb, int startpos, int range,
			 int stop, int total_size, rx_get_burst_fn get_burst,
			 rx_back_check_fn back_check, rx_fetch_char_fn fetch_char,
			 void *app_closure, struct re_registers *regs,
			 struct rx_search_state *resume_state,
			 struct rx_search_state *save_state)
#else
int
re_rx_search(rxb, startpos, range, stop, total_size,
			 get_burst, back_check, fetch_char,
			 app_closure, regs, resume_state, save_state)
struct re_pattern_buffer *rxb;
int startpos;
int range;
int stop;
int total_size;
rx_get_burst_fn get_burst;
rx_back_check_fn back_check;
rx_fetch_char_fn fetch_char;
void *app_closure;
struct re_registers *regs;
struct rx_search_state *resume_state;
struct rx_search_state *save_state;
#endif
{
	return rx_search(rxb, startpos, range, stop, total_size,
					 get_burst, back_check, fetch_char, app_closure,
					 regs, resume_state, save_state);
}

#if !defined(REGEX_MALLOC) && !defined(__GNUC__)
#ifdef __STDC__
int
re_search_2(struct re_pattern_buffer *rxb,
			__const__ char *string1, int size1,
			__const__ char *string2, int size2,
			int startpos, int range, struct re_registers *regs, int stop)
#else
int
re_search_2(rxb, string1, size1, string2, size2, startpos, range, regs,
			stop)
struct re_pattern_buffer *rxb;
__const__ char *string1;
int size1;
__const__ char *string2;
int size2;
int startpos;
int range;
struct re_registers *regs;
int stop;
#endif
{
	int ret;

	ret = inner_re_search_2(rxb, string1, size1, string2, size2, startpos,
							range, regs, stop);
	alloca(0);
	return ret;
}
#endif


/* Like re_search_2, above, but only one string is specified, and
 * doesn't let you say where to stop matching.
 */

#ifdef __STDC__
int
re_search(struct re_pattern_buffer *rxb, __const__ char *string,
		  int size, int startpos, int range, struct re_registers *regs)
#else
int re_search(rxb, string, size, startpos, range, regs)
struct re_pattern_buffer *rxb;
__const__ char *string;
int size;
int startpos;
int range;
struct re_registers *regs;
#endif
{
	return re_search_2(rxb, 0, 0, string, size, startpos, range, regs,
					   size);
}

#ifdef __STDC__
int
re_match_2(struct re_pattern_buffer *rxb,
		   __const__ char *string1, int size1,
		   __const__ char *string2, int size2,
		   int pos, struct re_registers *regs, int stop)
#else
int re_match_2(rxb, string1, size1, string2, size2, pos, regs, stop)
struct re_pattern_buffer *rxb;
__const__ char *string1;
int size1;
__const__ char *string2;
int size2;
int pos;
struct re_registers *regs;
int stop;
#endif
{
	struct re_registers some_regs;
	regoff_t start;
	regoff_t end;
	int srch;
	int save = rxb->regs_allocated;
	struct re_registers *regs_to_pass = regs;
	char *old_fastmap = rxb->fastmap;

	if (!regs) {
		some_regs.start = &start;
		some_regs.end = &end;
		some_regs.num_regs = 1;
		regs_to_pass = &some_regs;
		rxb->regs_allocated = REGS_FIXED;
	}

	rxb->fastmap = NULL;
	srch = re_search_2(rxb, string1, size1, string2, size2,
					   pos, 1, regs_to_pass, stop);
	rxb->fastmap = old_fastmap;
	if (regs_to_pass != regs)
		rxb->regs_allocated = save;
	if (srch < 0)
		return srch;
	return regs_to_pass->end[0] - regs_to_pass->start[0];
}

/* re_match is like re_match_2 except it takes only a single string.  */

#ifdef __STDC__
int
re_match(struct re_pattern_buffer *rxb,
		 __const__ char *string,
		 int size, int pos, struct re_registers *regs)
#else
int re_match(rxb, string, size, pos, regs)
struct re_pattern_buffer *rxb;
__const__ char *string;
int size;
int pos;
struct re_registers *regs;
#endif
{
	return re_match_2(rxb, string, size, 0, 0, pos, regs, size);
}



/* Set by `re_set_syntax' to the current regexp syntax to recognize.  Can
   also be assigned to arbitrarily: each pattern buffer stores its own
   syntax, so it can be changed between regex compilations.  */
reg_syntax_t re_syntax_options = RE_SYNTAX_EMACS;


/* Specify the precise syntax of regexps for compilation.  This provides
   for compatibility for various utilities which historically have
   different, incompatible syntaxes.

   The argument SYNTAX is a bit mask comprised of the various bits
   defined in regex.h.  We return the old syntax.  */

#ifdef __STDC__
reg_syntax_t re_set_syntax(reg_syntax_t syntax)
#else
reg_syntax_t re_set_syntax(syntax)
reg_syntax_t syntax;
#endif
{
	reg_syntax_t ret = re_syntax_options;

	re_syntax_options = syntax;
	return ret;
}


/* Set REGS to hold NUM_REGS registers, storing them in STARTS and
   ENDS.  Subsequent matches using PATTERN_BUFFER and REGS will use
   this memory for recording register information.  STARTS and ENDS
   must be allocated using the malloc library routine, and must each
   be at least NUM_REGS * sizeof (regoff_t) bytes long.

   If NUM_REGS == 0, then subsequent matches should allocate their own
   register data.

   Unless this function is called, the first search or match using
   PATTERN_BUFFER will allocate its own register data, without
   freeing the old data.  */

#ifdef __STDC__
void
re_set_registers(struct re_pattern_buffer *bufp,
				 struct re_registers *regs,
				 unsigned num_regs, regoff_t * starts, regoff_t * ends)
#else
void re_set_registers(bufp, regs, num_regs, starts, ends)
struct re_pattern_buffer *bufp;
struct re_registers *regs;
unsigned num_regs;
regoff_t *starts;
regoff_t *ends;
#endif
{
	if (num_regs) {
		bufp->regs_allocated = REGS_REALLOCATE;
		regs->num_regs = num_regs;
		regs->start = starts;
		regs->end = ends;
	} else {
		bufp->regs_allocated = REGS_UNALLOCATED;
		regs->num_regs = 0;
		regs->start = regs->end = (regoff_t) 0;
	}
}




#ifdef __STDC__
static int cplx_se_sublist_len(struct rx_se_list *list)
#else
static int cplx_se_sublist_len(list)
struct rx_se_list *list;
#endif
{
	int x = 0;

	while (list) {
		if ((long) list->car >= 0)
			++x;
		list = list->cdr;
	}
	return x;
}


/* For rx->se_list_cmp */

#ifdef __STDC__
static int
posix_se_list_order(struct rx *rx,
					struct rx_se_list *a, struct rx_se_list *b)
#else
static int posix_se_list_order(rx, a, b)
struct rx *rx;
struct rx_se_list *a;
struct rx_se_list *b;
#endif
{
	int al = cplx_se_sublist_len(a);
	int bl = cplx_se_sublist_len(b);

	if (!al && !bl)
		return ((a == b)
				? 0 : ((a < b) ? -1 : 1));

	else if (!al)
		return -1;

	else if (!bl)
		return 1;

	else {
		rx_side_effect *av = ((rx_side_effect *)
							  alloca(sizeof(rx_side_effect) * (al + 1)));
		rx_side_effect *bv = ((rx_side_effect *)
							  alloca(sizeof(rx_side_effect) * (bl + 1)));
		struct rx_se_list *ap = a;
		struct rx_se_list *bp = b;
		int ai, bi;

		for (ai = al - 1; ai >= 0; --ai) {
			while ((long) ap->car < 0)
				ap = ap->cdr;
			av[ai] = ap->car;
			ap = ap->cdr;
		}
		av[al] = (rx_side_effect) - 2;
		for (bi = bl - 1; bi >= 0; --bi) {
			while ((long) bp->car < 0)
				bp = bp->cdr;
			bv[bi] = bp->car;
			bp = bp->cdr;
		}
		bv[bl] = (rx_side_effect) - 1;

		{
			int ret;
			int x = 0;

			while (av[x] == bv[x])
				++x;
			ret = (((unsigned *) (av[x]) < (unsigned *) (bv[x])) ? -1 : 1);
			return ret;
		}
	}
}




/* re_compile_pattern is the GNU regular expression compiler: it
   compiles PATTERN (of length SIZE) and puts the result in RXB.
   Returns 0 if the pattern was valid, otherwise an error string.

   Assumes the `allocated' (and perhaps `buffer') and `translate' fields
   are set in RXB on entry.

   We call rx_compile to do the actual compilation.  */

#ifdef __STDC__
__const__ char *re_compile_pattern(__const__ char *pattern,
								   int length,
								   struct re_pattern_buffer *rxb)
#else
__const__ char *re_compile_pattern(pattern, length, rxb)
__const__ char *pattern;
int length;
struct re_pattern_buffer *rxb;
#endif
{
	reg_errcode_t ret;

	/* GNU code is written to assume at least RE_NREGS registers will be set
	   (and at least one extra will be -1).  */
	rxb->regs_allocated = REGS_UNALLOCATED;

	/* And GNU code determines whether or not to get register information
	   by passing null for the REGS argument to re_match, etc., not by
	   setting no_sub.  */
	rxb->no_sub = 0;

	rxb->rx.local_cset_size = 256;

	/* Match anchors at newline.  */
	rxb->newline_anchor = 1;

	rxb->re_nsub = 0;
	rxb->start = 0;
	rxb->se_params = 0;
	rxb->rx.nodec = 0;
	rxb->rx.epsnodec = 0;
	rxb->rx.instruction_table = 0;
	rxb->rx.nfa_states = 0;
	rxb->rx.se_list_cmp = posix_se_list_order;
	rxb->rx.start_set = 0;

	ret = rx_compile(pattern, length, re_syntax_options, rxb);
	alloca(0);
	return rx_error_msg[(int) ret];
}


#ifdef __STDC__
int re_compile_fastmap(struct re_pattern_buffer *rxb)
#else
int re_compile_fastmap(rxb)
struct re_pattern_buffer *rxb;
#endif
{
	rx_blow_up_fastmap(rxb);
	return 0;
}




/* Entry points compatible with 4.2 BSD regex library.  We don't define
   them if this is an Emacs or POSIX compilation.  */

#if (!defined (emacs) && !defined (_POSIX_SOURCE)) || defined(USE_BSD_REGEX)

/* BSD has one and only one pattern buffer.  */
static struct re_pattern_buffer rx_comp_buf;

#ifdef __STDC__
char *re_comp(__const__ char *s)
#else
char *re_comp(s)
__const__ char *s;
#endif
{
	reg_errcode_t ret;

	if (!s || (*s == '\0')) {
		if (!rx_comp_buf.buffer)
			return "No previous regular expression";
		return 0;
	}

	if (!rx_comp_buf.fastmap) {
		rx_comp_buf.fastmap = (char *) malloc(1 << CHARBITS);
		if (!rx_comp_buf.fastmap)
			return "Memory exhausted";
	}

	/* Since `rx_exec' always passes NULL for the `regs' argument, we
	   don't need to initialize the pattern buffer fields which affect it.  */

	/* Match anchors at newlines.  */
	rx_comp_buf.newline_anchor = 1;

	rx_comp_buf.re_nsub = 0;
	rx_comp_buf.start = 0;
	rx_comp_buf.se_params = 0;
	rx_comp_buf.rx.nodec = 0;
	rx_comp_buf.rx.epsnodec = 0;
	rx_comp_buf.rx.instruction_table = 0;
	rx_comp_buf.rx.nfa_states = 0;
	rx_comp_buf.rx.start = 0;
	rx_comp_buf.rx.se_list_cmp = posix_se_list_order;
	rx_comp_buf.rx.start_set = 0;
	rx_comp_buf.rx.local_cset_size = 256;

	ret = rx_compile(s, strlen(s), re_syntax_options, &rx_comp_buf);
	alloca(0);

	/* Yes, we're discarding `__const__' here.  */
	return (char *) rx_error_msg[(int) ret];
}


#ifdef __STDC__
int re_exec(__const__ char *s)
#else
int re_exec(s)
__const__ char *s;
#endif
{
	__const__ int len = strlen(s);

	return
		0 <= re_search(&rx_comp_buf, s, len, 0, len,
					   (struct re_registers *) 0);
}
#endif							/* not emacs and not _POSIX_SOURCE */



/* POSIX.2 functions.  Don't define these for Emacs.  */

#if !defined(emacs)

/* regcomp takes a regular expression as a string and compiles it.

   PREG is a regex_t *.  We do not expect any fields to be initialized,
   since POSIX says we shouldn't.  Thus, we set

     `buffer' to the compiled pattern;
     `used' to the length of the compiled pattern;
     `syntax' to RE_SYNTAX_POSIX_EXTENDED if the
       REG_EXTENDED bit in CFLAGS is set; otherwise, to
       RE_SYNTAX_POSIX_BASIC;
     `newline_anchor' to REG_NEWLINE being set in CFLAGS;
     `fastmap' and `fastmap_accurate' to zero;
     `re_nsub' to the number of subexpressions in PATTERN.

   PATTERN is the address of the pattern string.

   CFLAGS is a series of bits which affect compilation.

     If REG_EXTENDED is set, we use POSIX extended syntax; otherwise, we
     use POSIX basic syntax.

     If REG_NEWLINE is set, then . and [^...] don't match newline.
     Also, regexec will try a match beginning after every newline.

     If REG_ICASE is set, then we considers upper- and lowercase
     versions of letters to be equivalent when matching.

     If REG_NOSUB is set, then when PREG is passed to regexec, that
     routine will report only success or failure, and nothing about the
     registers.

   It returns 0 if it succeeds, nonzero if it doesn't.  (See regex.h for
   the return codes and their meanings.)  */


#ifdef __STDC__
int regcomp(regex_t * preg, __const__ char *pattern, int cflags)
#else
int regcomp(preg, pattern, cflags)
regex_t *preg;
__const__ char *pattern;
int cflags;
#endif
{
	reg_errcode_t ret;
	unsigned syntax

		=
		cflags & REG_EXTENDED ? RE_SYNTAX_POSIX_EXTENDED :
		RE_SYNTAX_POSIX_BASIC;

	/* regex_compile will allocate the space for the compiled pattern.  */
	preg->buffer = 0;
	preg->allocated = 0;
	preg->fastmap = malloc(256);
	if (!preg->fastmap)
		return REG_ESPACE;
	preg->fastmap_accurate = 0;

	if (cflags & REG_ICASE) {
		unsigned i;

		preg->translate = (unsigned char *) malloc(256);
		if (!preg->translate)
			return (int) REG_ESPACE;

		/* Map uppercase characters to corresponding lowercase ones.  */
		for (i = 0; i < CHAR_SET_SIZE; i++)
			preg->translate[i] = isupper(i) ? tolower(i) : i;
	} else
		preg->translate = 0;

	/* If REG_NEWLINE is set, newlines are treated differently.  */
	if (cflags & REG_NEWLINE) {	/* REG_NEWLINE implies neither . nor [^...] match newline.  */
		syntax &= ~RE_DOT_NEWLINE;
		syntax |= RE_HAT_LISTS_NOT_NEWLINE;
		/* It also changes the matching behavior.  */
		preg->newline_anchor = 1;
	} else
		preg->newline_anchor = 0;

	preg->no_sub = !!(cflags & REG_NOSUB);

	/* POSIX says a null character in the pattern terminates it, so we
	   can use strlen here in compiling the pattern.  */
	preg->re_nsub = 0;
	preg->start = 0;
	preg->se_params = 0;
	preg->syntax_parens = 0;
	preg->rx.nodec = 0;
	preg->rx.epsnodec = 0;
	preg->rx.instruction_table = 0;
	preg->rx.nfa_states = 0;
	preg->rx.local_cset_size = 256;
	preg->rx.start = 0;
	preg->rx.se_list_cmp = posix_se_list_order;
	preg->rx.start_set = 0;
	ret = rx_compile(pattern, strlen(pattern), syntax, preg);
	alloca(0);

	/* POSIX doesn't distinguish between an unmatched open-group and an
	   unmatched close-group: both are REG_EPAREN.  */
	if (ret == REG_ERPAREN)
		ret = REG_EPAREN;

	return (int) ret;
}


/* regexec searches for a given pattern, specified by PREG, in the
   string STRING.

   If NMATCH is zero or REG_NOSUB was set in the cflags argument to
   `regcomp', we ignore PMATCH.  Otherwise, we assume PMATCH has at
   least NMATCH elements, and we set them to the offsets of the
   corresponding matched substrings.

   EFLAGS specifies `execution flags' which affect matching: if
   REG_NOTBOL is set, then ^ does not match at the beginning of the
   string; if REG_NOTEOL is set, then $ does not match at the end.

   We return 0 if we find a match and REG_NOMATCH if not.  */

#ifdef __STDC__
int
regexec(__const__ regex_t * preg, __const__ char *string,
		size_t nmatch, regmatch_t pmatch[], int eflags)
#else
int regexec(preg, string, nmatch, pmatch, eflags)
__const__ regex_t *preg;
__const__ char *string;
size_t nmatch;
regmatch_t pmatch[];
int eflags;
#endif
{
	int ret;
	struct re_registers regs;
	regex_t private_preg;
	int len = strlen(string);
	boolean want_reg_info = !preg->no_sub && nmatch > 0;

	private_preg = *preg;

	private_preg.not_bol = !!(eflags & REG_NOTBOL);
	private_preg.not_eol = !!(eflags & REG_NOTEOL);

	/* The user has told us exactly how many registers to return
	 * information about, via `nmatch'.  We have to pass that on to the
	 * matching routines.
	 */
	private_preg.regs_allocated = REGS_FIXED;

	if (want_reg_info) {
		regs.num_regs = nmatch;
		regs.start = ((regoff_t *) malloc((nmatch) * sizeof(regoff_t)));
		regs.end = ((regoff_t *) malloc((nmatch) * sizeof(regoff_t)));
		if (regs.start == 0 || regs.end == 0)
			return (int) REG_NOMATCH;
	}

	/* Perform the searching operation.  */
	ret = re_search(&private_preg, string, len,
					/* start: */ 0,
					/* range: */ len,
					want_reg_info ? &regs : (struct re_registers *) 0);

	/* Copy the register information to the POSIX structure.  */
	if (want_reg_info) {
		if (ret >= 0) {
			unsigned r;

			for (r = 0; r < nmatch; r++) {
				pmatch[r].rm_so = regs.start[r];
				pmatch[r].rm_eo = regs.end[r];
			}
		}

		/* If we needed the temporary register info, free the space now.  */
		free(regs.start);
		free(regs.end);
	}

	/* We want zero return to mean success, unlike `re_search'.  */
	return ret >= 0 ? (int) REG_NOERROR : (int) REG_NOMATCH;
}


/* Returns a message corresponding to an error code, ERRCODE, returned
   from either regcomp or regexec.   */

#ifdef __STDC__
size_t
regerror(int errcode, __const__ regex_t * preg,
		 char *errbuf, size_t errbuf_size)
#else
size_t regerror(errcode, preg, errbuf, errbuf_size)
int errcode;
__const__ regex_t *preg;
char *errbuf;
size_t errbuf_size;
#endif
{
	__const__ char *msg
		= rx_error_msg[errcode] == 0 ? "Success" : rx_error_msg[errcode];
	size_t msg_size = strlen(msg) + 1;	/* Includes the 0.  */

	if (errbuf_size != 0) {
		if (msg_size > errbuf_size) {
			strncpy(errbuf, msg, errbuf_size - 1);
			errbuf[errbuf_size - 1] = 0;
		} else
			strcpy(errbuf, msg);
	}

	return msg_size;
}


/* Free dynamically allocated space used by PREG.  */

#ifdef __STDC__
void regfree(regex_t * preg)
#else
void regfree(preg)
regex_t *preg;
#endif
{
	if (preg->buffer != 0)
		free(preg->buffer);
	preg->buffer = 0;
	preg->allocated = 0;

	if (preg->fastmap != 0)
		free(preg->fastmap);
	preg->fastmap = 0;
	preg->fastmap_accurate = 0;

	if (preg->translate != 0)
		free(preg->translate);
	preg->translate = 0;
}

#endif							/* not emacs  */