Celestin Apprentice 2/Apprentice-Release2.iso/Tools/MPW/sed 2.0.3/rx.c

C/C++ Source or Header | 1994-01-09 | 216.9 KB | 4,417 lines | [TEXT/MPS ]

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

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

This program 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 General Public License
along with this software; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

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

static char rx_version_string[] = "GNU Rx version 0.03";

            /* ``Too hard!''
             *        -- anon.
             */

#include <stdio.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>
#include <stdio.h>
#include "rx.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


/* This page is decls to the interesting subsystems and lower layers
 * of rx.  Everything which doesn't have a public counterpart in
 * regex.c is declared here.
 *
 * A useful (i hope) system is obtained by removing all or part of the regex.c
 * reimplementation and making these all extern.  I think this package
 * could be used to implement on-line lexers and parsers and who knows what
 * else.
 */
/* In the definitions, these functions are qualified by `RX_DECL' */
#define RX_DECL static

#ifdef __STDC__

RX_DECL int rx_bitset_is_subset (int size, rx_Bitset a, rx_Bitset b);
RX_DECL void rx_bitset_null (int size, rx_Bitset b);
RX_DECL void rx_bitset_universe (int size, rx_Bitset b);
RX_DECL void rx_bitset_complement (int size, rx_Bitset b);
RX_DECL void rx_bitset_assign (int size, rx_Bitset a, rx_Bitset b);
RX_DECL void rx_bitset_union (int size, rx_Bitset a, rx_Bitset b);
RX_DECL void rx_bitset_intersection (int size,
                     rx_Bitset a, rx_Bitset b);
RX_DECL void rx_bitset_difference (int size, rx_Bitset a, rx_Bitset b);
RX_DECL unsigned long rx_bitset_hash (int size, rx_Bitset b);
RX_DECL struct rx_hash_item * rx_hash_find (struct rx_hash * table,
                        unsigned long hash,
                        void * value,
                        struct rx_hash_rules * rules);
RX_DECL struct rx_hash_item * rx_hash_store (struct rx_hash * table,
                         unsigned long hash,
                         void * value,
                         struct rx_hash_rules * rules);
RX_DECL void rx_hash_free (struct rx_hash_item * it,
               struct rx_hash_rules * rules);
RX_DECL rx_Bitset rx_cset (struct rx *rx);
RX_DECL rx_Bitset rx_copy_cset (struct rx *rx, rx_Bitset a);
RX_DECL void rx_free_cset (struct rx * rx, rx_Bitset c);
RX_DECL struct rexp_node * rexp_node (struct rx *rx,
                      enum rexp_node_type type);
RX_DECL struct rexp_node * rx_mk_r_cset (struct rx * rx,
                     rx_Bitset b);
RX_DECL struct rexp_node * rx_mk_r_concat (struct rx * rx,
                       struct rexp_node * a,
                       struct rexp_node * b);
RX_DECL struct rexp_node * rx_mk_r_alternate (struct rx * rx,
                          struct rexp_node * a,
                          struct rexp_node * b);
RX_DECL struct rexp_node * rx_mk_r_opt (struct rx * rx,
                    struct rexp_node * a);
RX_DECL struct rexp_node * rx_mk_r_star (struct rx * rx,
                     struct rexp_node * a);
RX_DECL struct rexp_node * rx_mk_r_2phase_star (struct rx * rx,
                        struct rexp_node * a,
                        struct rexp_node * b);
RX_DECL struct rexp_node * rx_mk_r_side_effect (struct rx * rx,
                        rx_side_effect a);
RX_DECL struct rexp_node * rx_mk_r_data  (struct rx * rx,
                      void * a);
RX_DECL void rx_free_rexp (struct rx * rx, struct rexp_node * node);
RX_DECL struct rexp_node * rx_copy_rexp (struct rx *rx,
                     struct rexp_node *node);
RX_DECL struct rx_nfa_state * rx_nfa_state (struct rx *rx);
RX_DECL void rx_free_nfa_state (struct rx_nfa_state * n);
RX_DECL struct rx_nfa_state * rx_id_to_nfa_state (struct rx * rx,
                          int id);
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);
RX_DECL void rx_free_nfa_edge (struct rx_nfa_edge * e);
RX_DECL void rx_free_nfa (struct rx *rx);
RX_DECL int rx_build_nfa (stru }


    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;
    };
}


/* NAME_RX->NFA_STATES identifies all nodes with non-epsilon transitions.
 * 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.
 */

/* 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
};

static DEF_POOL(sel_pool, struct rx_se_list);

#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 = ((struct rx_se_list *)
               chunk_malloc (&sel_pool));
  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 = ((struct rx_se_list *)
                      chunk_malloc (&sel_pool));
    *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;
}


/* This page: more data structures for nfa->supernfa.  Specificly,
 * sets of nfa states.
 */

#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
};


/* CONS -- again, sets with == elements are ==. */

static DEF_POOL(nfa_sets, struct rx_nfa_state_set);

#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 = ((struct rx_nfa_state_set *)
                  chunk_malloc (&nfa_sets));
      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;
};


#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;

  /      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;
}



static int
supersetcmp (va, vb)
     void * va;
     void * vb;
{
  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)));
  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
{
  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_su_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;

  /* 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 = solution;
          rx_protect_superset (rx, solution);
          solution =
            rx_superstate_eclosure_union (rx, solution, pf->destset);
          if (!solution)
            return 0;
          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;
    }
  rx_protect_superset (rx, solution);
  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))
      {
       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,
             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;
     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,
           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;
     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 (   ((int)rexp->params.side_effect >= 0)
        && (params [(int)rexp->params.side_effect].se == re_se_backref))
      out[ params [(int)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;
    }
}


/* 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;
    return MAX (l, r);
      }
    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 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_X_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 "rx.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 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
    !((int)rexp->params.side_effect > 0
      ? idempotent_complex_se [ params [(int)rexp->params.side_effect].se ]
      : idempotent_se [-(int)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 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 ((int)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 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__
reg_errcode_t
rx_compile (const char *pattern, int size,
        reg_syntax_t syntax,
        struct re_pattern_buffer * rxb)
#else
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.  */
  char *translate = rxb->translate ? rxb->translate : 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 = TALLOC (INIT_COMPILE_STACK_SIZE, 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 = rx_mk_r_cset (&rxb->rx, cs);
          struct rexp_node * fake_state
            = rx_mk_r_concat (&rxb->rx, pushback, lit_t);
          struct rexp_node * phase2
            = rx_mk_r_concat (&rxb->rx, checker, fake_state);
          struct rexp_node * popper
            = rx_mk_r_side_effect (&rxb->rx,
                       (rx_side_effect)re_se_poppos);
          struct rexp_node * star
            = rx_mk_r_2phase_star (&rxb->rx, inner_exp, phase2);
          struct rexp_node * a
            = rx_mk_r_concat (&rxb->rx, pusher, star);
          struct rexp_node * 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 << BYTEWIDTH; 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)
                {
                  RETALLOC (compile_stack.stack, compile_stack.size << 1,
                            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
            = rx_mk_r_cset (&rxb->rx, cs);
              struct rexp_node * phase2
            = rx_mk_r_concat (&rxb->rx, pushback, lit_t);
              struct rexp_node * loop
            = rx_mk_r_2phase_star (&rxb->rx, phase1, phase2);
              struct rexp_node * push_n_loop
            = rx_mk_r_concat (&rxb->rx, push0, loop);
              struct rexp_node * final_test
            = rx_mk_r_side_effect (&rxb->rx,
                           (rx_side_effect)end_se);
              struct rexp_node * 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 = NULL;

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

               if (!(syntax & RE_NO_BK_BRACES))
  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_ESI_t);
      if (regs->start == 0 || regs->end == 0)
        return -2;
      rxb->regs_allocated = REGS_REALLOCATE;
    }
      else if (rxb->regs_allocated == REGS_REALLOCATE)
    { /* Yes.  If we need more elements than were already
         allocated, reallocate them.  If we need fewer, just
         leave it alone.  */
      if (regs->num_regs < num_regs + 1)
        {
          regs->num_regs = num_regs + 1;
          RETALLOC (regs->start, regs->num_regs, regoff_t);
          RETALLOC (regs->end, regs->num_regs, regoff_t);
          if (regs->start == 0 || regs->end == 0)
        return -2;
        }
    }
      else if (rxb->regs_allocated != REGS_FIXED)
    return -2;

      if (regs->num_regs < num_regs + 1)
    {
      best_lpspace = ((regoff_t *)
              REGEX_ALLOCATE (num_regs * sizeof(regoff_t)));
      best_rpspace = ((regoff_t *)
              REGEX_ALLOCATE (num_regs * sizeof(regoff_t)));
      best_lparen = best_lpspace;
      best_rparen = best_rpspace;
    }
      else
    {
      best_lparen = regs->start;
      best_rparen = regs->end;
    }
    }

  lparen = (regoff_t *) REGEX_ALLOCATE (num_regs * sizeof(regoff_t));
  rparen = (regoff_t *) REGEX_ALLOCATE (num_regs * sizeof(regoff_t));

  if (!(best_rparen && best_lparen && lparen && rparen))
    return -2;

  best_last_l = best_last_r = -1;



  /***** fastmap/search loop, initialization */

  /* This is the loop that scans using the fastmap, and sometimes tries to
   * match. From this point on, don't return.  Instead, assign to ret_val
   * and goto fail.
   */
  {
    const char * translate = rxb->translate ? rxb->translate : id_translation;

    /** This is state associated with returning to the caller. */

    int ret_val = -1;

    /*   A sentinal is sometimes installed in the fastmap.  This records
     *   where so it can be removed before returning.
     */
    int fastmap_chr = -1;
    int fastmap_val;

    /** End of state associated with returning to the caller. */

    /** Start of variables associated with the fastmap based search: */

    char * fastmap = rxb->fastmap ? (char *)rxb->fastmap : (char *)slowmap;
    int search_direction;    /* 1 or -1 */
    int search_end;        /* first position to not try */
    int offset;            /* either size1 or 0 as string == string2 */

    /* The string-pair position of the fastmap/search loop: */
    const unsigned char * pos;    /* The current pos. */
    const unsigned char * string; /* The current string half. */
    const unsigned char * end;    /* End of current string. */
    int size;            /* Current string's size */
    int half;            /* 0 means string1, 1 means string2 */

    /** End of variables associated with the fastmap based search: */


    /** Start of variables associated with trying a match
     *  after the fastmap has found a plausible starting point.
     */

    struct rx_superstate * start_super = 0; /* The superNFA start state. */

    /*
     * Two nfa's were compiled.
     * `0' is complete.
     * `1' faster but gets registers wrong and ends too soon.
     */
    int nfa_choice = ((regs && !rxb->least_subs) ? '\0' : '\1');

    const unsigned char * abs_end; /* Don't fetch a character from here. */
    int first_found;        /* If true, return after finding any match. */

    /** End of variables associated with trying a match. */

    /* Update the fastmap now if not correct already.
     * When the regexp was compiled, the fastmap was computed
     * and stored in a bitset.  This expands the bitset into a
     * character array containing 1s and 0s.
     */
    if ((fastmap == rxb->fastmap) && !rxb->fastmap_accurate)
      rx_blow_up_fastmap (rxb);

    /* Now we build the starting state of the supernfa. */
    {
      struct rx_superset * start_contents;
      struct rx_nfa_state_set * start_nfa_set;

      /* We presume here that the nfa start state has only one
       * possible future with no side effects.
       */
      start_nfa_set = rxb->start->futures->destset;
      if (   rxb->rx.start_set
      && (rxb->rx.start_set->starts_for == &rxb->rx))
    start_contents = rxb->rx.start_set;
      else
    {
      start_contents =
        rx_superstate_eclosure_union (&rxb->rx,
                      rx_superset_cons (&rxb->rx, 0, 0),
                      start_nfa_set);

      if (!start_contents)
        return -1;

      start_contents->starts_for = &rxb->rx;
      rxb->rx.start_set = start_contents;
    }
      if (   start_contents->superstate
      && (start_contents->superstate->rx_id == rxb->rx.rx_id))
    {
      start_super = start_contents->superstate;
      rx_lock_superstate (&rxb->rx, start_super);
    }
      else
    {
      rx_protect_superset (&rxb->rx, start_contents);

      start_super = rx_superstate (&rxb->rx, start_contents);
      if (!start_super)
        return -1;
      rx_lock_superstate (&rxb->rx, start_super);
      rx_release_superset (&rxb->rx, start_contents);
    }
    }

    /* This computes an upper bound on string addresses for use by
     * the match-test.
     */
    abs_end = ((const unsigned char *) ((stop <= size1)
                    ? string1 + stop
                    : string2 + stop - size1));

    /* We have the option to look for the best match or the first
     * one we can find.  If the user isn't asking for register information,
     * we don't need to find the best match.
     */
    first_found = !regs;

    /* Compute search_end & search_direction for the fastmap loop. */
    if (range >= 0)
      {
    search_end = MIN (size1 + size2, startpos + range) + 1;
    search_direction = 1;
      }
    else
      {
    search_end = MAX(-1, startpos + range);
    search_direction = -1;
      }

    /* The vacuous search always turns up nothing. */
    if ((search_direction == 1)
    ? (startpos > search_end)
    : (startpos < search_end))
      return -1;

    /* Set string/size/offset/end -- the state that tells the fastmap
     * loop which half of the string we're in.  Also set pos, which
     * is the addr of the current fastmap scan position.
     */
    if (!string2 || (startpos < size1))
      {
    string = (const unsigned char *)string1;
    size = size1;
    offset = 0;
    pos = (const unsigned char *)(string1 + startpos);
    half = 0;
    end = (const unsigned char *)MIN(string1 + size1, string1 + stop);
      }
    else
      {
    string = (const unsigned char *)string2;
    size = size2;
    offset = size1;
    pos = (const unsigned char *)(string2 + startpos - size1);
    half = 1;
    end = (const unsigned char *)MIN(string2 + size2,
                     string2 + stop - size1);
      }




    /***** fastmap/search loop,  body */


  init_fastmap_sentinal:

    /* For the sake of fast fastmapping, set a sentinal in the fastmap.
     * This sentinal will trap the fastmap loop when it reaches the last
     * valid character in a string half.
     *
     * This must be reset when the fastmap/search loop crosses a string
     * boundry, and before returning to the caller.  So sometimes,
     * the fastmap loop is restarted with `continue', othertimes by
     * `goto init_fastmap_sentinal'.
     */
    if (size)
      {
    fastmap_chr = ((search_direction == 1)
               ? *(end - 1)
               : *string);
    fastmap_val = fastmap[fastmap_chr];
    fastmap[fastmap_chr] = 1;
      }
    else
      fastmap_chr = -1;

    do
      {
    /* If we haven't reached the end of a string half, and if the
     * pattern can't match the empty string, then the fastmap
     * optimization applies.  This conditional scans using the
     * fastmap -- stoping when a string half ends, or when a
     * plausible starting point for a match is found.
     * It updates HIT_BOUND to tell which case occured.
     */
    if (pos == end)
      goto fastmap_hit_bound;
    else
      {
        if (search_direction == 1)
          {
        if (fastmap_val)
          {
            for (;;)
              {
            while (!fastmap[*pos])
              ++pos;
            goto commence_a_matchin;
              }
          }
        else
          {
            for (;;)
              {
            while (!fastmap[*pos])
              ++pos;
            if (*pos != fastmap_chr)
              goto commence_a_matchin;
            else
              {
                ++pos;
                if (pos == end)
                  goto fastmap_hit_bound;
              }
              }
          }
          }
        else
          {
        const unsigned char * bound = string - 1;
        for (;;)
          {
            while (!fastmap[*pos])
              --pos;
            if ((*pos != fastmap_chr) || fastmap_val)
              goto commence_a_matchin;
            else
              {
            --pos;
            if (pos == bound)
              goto fastmap_hit_bound;
              }
          }
          }
      }

      fastmap_hit_bound:
    {
      /* If we hit a bound, it may simply be time to switch sides
       * between strings.
       */
      if ((search_direction == 1) && string2 && (half == 0))
        {
          string = (const unsigned char *)string2;
          size = size2;
          offset = size1;
          half = 1;
          end = (const unsigned char *)MIN(string2 + size2,
                           string2 + stop - size1);
          startpos = size1;
          pos = (const unsigned char *)string2;
          goto init_fastmap_sentinal;
        }
      else if (   string1
           && (search_direction == -1)
           && (half == 1))
        {
          string = (const unsigned char *)string1;
          size = size1;
          offset = 0;
          end = (const unsigned char *)string1 + size1;
          half = 0;
          startpos = size1 - 1;
          pos = (const unsigned char *)string1 + size1 - 1;
          goto init_fastmap_sentinal;
        }
      /* ...not a string split, simply no more string.
       *
       * When searching backward, running out of string
       * is reason to quit.
       */
      else if (search_direction == -1)
        goto finish;

      /* ...when searching forward, we allow the possibility
       * of an (empty) match after the last character in the
       * virtual string.  So, fall through to the matcher
       */
    }


      commence_a_matchin:

    /***** fastmap/search loop body
     *          test for a match that begins at pos
     */

    /* Now the fastmap loop has brought us to a plausible
     * starting point for a match.  So, it's time to run the
     * NFA and see if a match occured.
     */

    startpos = pos - string + offset;
    if (startpos == search_end)
      goto finish;

    last_l = last_r = 0;
    lparen[0] = startpos;    /* We know match-begin for this test... */

    /* The test matcher is essentially a recursive function
     * that does an exhaustive run of the superNFA at the
     * test position.  For performance, that function has
     * been in-lined by hand.
     */

#undef OF
#ifndef HAVE_GNUC_LABELS
#define OF(A,B)    A
#else
#define OF(A,B)    A: B
      static void * rx_labels_instruction_table[] =
        {
          [rx_backtrack_point] &&backtrack_point,
          [rx_backtrack] &&backtrack,
          [rx_do_side_effects] &&do_side_effects,
          [rx_cache_miss] &&cache_miss,
          [rx_next_char] 0,
          [rx_error_inx] 0
        };
#endif
    {
      /* The current superNFA position of the matcher. */
      struct rx_superstate * super = start_super;

      /* The matcher interprets a series of instruction frames.
       * This is the `instruction counter' for the interpretation.
       */
      struct rx_inx * ifr;

      /* We insert a ghost character in the string to prime
       * the nfa.  tst_pos, tst_str_half, and tst_end_half
       * keep track of the test-match position and string-half.
       */
      const unsigned char * tst_pos = pos - 1;
      int tst_half = half;
      unsigned char c = nfa_choice;

      const unsigned char * tst_str_half = string;
      const unsigned char * tst_end_half = end;

      struct stack_chunk * counter_stack = 0;
      struct stack_chunk * backtrack_stack = 0;
      int backtrack_frame_bytes =
        (sizeof (struct backtrack_frame)
         + (rxb->match_regs_on_stack
        ? sizeof (regoff_t) * (num_regs + 1) * 2
        : 0));
      int chunk_bytes = backtrack_frame_bytes * 64;
      struct stack_chunk * free_chunks = 0;

#ifdef RX_DEBUG
      int backtrack_depth = 0;
#endif

      /* To return from this function, set test_ret and
       * `goto test_do_return'.
       *
       * Possible return values are:
       *     1   --- end of string while the superNFA is still going
       *     0   --- internal error (out of memory)
       *    -1   --- search completed by reaching the superNFA fail state
       *    -2   --- a match was found, maybe not the longest.
       *
       * When the search is complete (-1), best_last_r indicates whether
       * a match was found.
       *
       * -2 is return only if first_found is non-zero.
       *
       * if first_found is non-zero, a return of -1 indicates no match,
       * otherwise, best_last_r has to be checked.
       */
      int test_ret = -1;

      while (1)
        {
          int inx;
#ifdef RX_DEBUG
          /* There is a search tree with every node as set of deterministic
           * transitions in the super nfa.  For every branch of a
           * backtrack point is an edge in the tree.
           * This counts up a pre-order of nodes in that tree.
           * It's saved on the search stack and printed when debugging.
           */
          int line_no = 0;
          int lines_found = 0;
#endif


        top_of_cycle:
          /* A superstate is basicly a transition table, indexed by
           * characters from the string being tested, and containing
           * RX_INX structures.
           */
          ifr = &super->transitions [c];

        recurse_test_match:
          /* This is the point to which control is sent when the
           * test matcher recurses.  Before jumping here, some variables
           * need to be saved on the stack and setup for the recursion.
           */

        restart:
          /* Some instructions don't advance the matcher, but just
           * carry out some side effects and fetch a new instruction.
           * To dispatch that new instruction, `goto restart'.
           */

          {
        struct rx_inx * next_tr_table = (struct rx_inx *)ifr->data;
        struct rx_inx * this_tr_table = super->transitions;
        /* The fastest route through the loop is when the instruction
         * is RX_NEXT_CHAR.  This case is detected when IFR->DATA
         * is non-zero.  In that case, it points to the next
         * superstate.
         *
         * This allows us to not bother fetching the bytecode.
         */
        while (next_tr_table)
          {
#ifdef RX_DEBUG
            if (rx_debug_trace)
              {
            struct rx_superset * setp;

            fprintf (stderr, "%d %d>> re_next_char @ %d (%d)",
                 line_no,
                 backtrack_depth,
                 (tst_pos - tst_str_half
                  + (tst_half == 0
                     ? 0 : size1)), c);

            super =
              ((struct rx_superstate *)
               ((char *)this_tr_table
                - ((unsigned long)
                   ((struct rx_superstate *)0)->transitions)));

            setp = super->contents;
            fprintf (stderr, "   superstet (rx=%d, &=%x: ",
                 rxb->rx.rx_id, setp);
            while (setp)
              {
                fprintf (stderr, "%d ", setp->id);
                setp = setp->cdr;
              }
            fprintf (stderr, "\n");
              }
#endif
            this_tr_table = next_tr_table;
            ++tst_pos;
            if (tst_pos == tst_end_half)
              {
            if (   (tst_pos != abs_end)
                && string2
                && half == 0)
              {
                /* Here we are crossing the break
                 * in a split string.
                 */
                tst_str_half = (const unsigned char *)string2;
                tst_end_half = abs_end;
                tst_pos = (const unsigned char *)string2;
                tst_half = 1;
              }
            else
              {
                test_ret = 1;
                goto test_do_return;
              }
              }
            c = *tst_pos;
            ifr = this_tr_table + c;
            next_tr_table = (struct rx_inx *)ifr->data;
          }

        /* Here when we ran out cached next-char transitions.
         * So, it will be necessary to do a more expensive
         * dispatch on the current instruction.  The superstate
         * pointer is allowed to become invalid during next-char
         * transitions -- now we must bring it up to date.
         */
        super =
          ((struct rx_superstate *)
           ((char *)this_tr_table
            - ((unsigned long)
               ((struct rx_superstate *)0)->transitions)));
          }

          /* We've encountered an instruction other than next-char.
           * Dispatch that instruction:
           */
          inx = (int)ifr->inx;
#ifdef HAVE_GNUC_LABELS
          goto *rx_labels_instruction_table[inx];
#endif
#ifdef RX_DEBUG
          if (rx_debug_trace)
        {
          struct rx_superset * setp = super->contents;

          fprintf (stderr, "%d %d>> %s @ %d (%d)", line_no,
               backtrack_depth,
               inx_names[inx],
               (tst_pos - tst_str_half
                + (tst_half == 0 ? 0 : size1)), c);

          fprintf (stderr, "   superstet (rx=%d, &=%x: ",
               rxb->rx.rx_id, setp);
          while (setp)
            {
              fprintf (stderr, "%d ", setp->id);
              setp = setp->cdr;
            }
          fprintf (stderr, "\n");
        }
#endif
          switch ((enum rx_opcode)inx)
        {
        case OF(rx_do_side_effects,do_side_effects):

          /*  RX_DO_SIDE_EFFECTS occurs when we cross epsilon
           *  edges associated with parentheses, backreferencing, etc.
           */
          {
            struct rx_distinct_future * df =
              (struct rx_distinct_future *)ifr->data_2;
            struct rx_se_list * el = df->effects;
            /* Side effects come in lists.  This walks down
             * a list, dispatching.
             */
            while (el)
              {
#ifdef HAVE_GNUC_LABELS
            static void * se_labels[] =
              {
                [-re_se_try] &&se_try,
                [-re_se_pushback] &&se_pushback,
                [-re_se_push0] &&se_push0,
                [-re_se_pushpos] &&se_pushpos,
                [-re_se_chkpos] &&se_chkpos,
                [-re_se_poppos] &&se_poppos,
#ifdef emacs
                [-re_se_at_dot] &&se_at_dot,
                [-re_se_syntax] &&se_syntax,
                [-re_se_not_syntax] &&se_not_syntax,
#endif
                [-re_se_begbuf] &&se_begbuf,
                [-re_se_hat] &&se_hat,
                [-re_se_wordbeg] &&se_wordbeg,
                [-re_se_wordbound] &&se_wordbound,
                [-re_se_notwordbound] &&se_notwordbound,
                [-re_se_wordend] &&se_wordend,
                [-re_se_endbuf] &&se_endbuf,
                [-re_se_dollar] &&se_dollar,
                [-re_se_fail] &&se_fail,
              };
            static void * se_lables2[] =
              {
                [re_se_win] &&se_win
                [re_se_lparen] &&se_lparen,
                [re_se_rparen] &&se_rparen,
                [re_se_backref] &&se_backref,
                [re_se_iter] &&se_iter,
                [re_se_end_iter] &&se_end_iter,
                [re_se_tv] &&se_tv
              };
#endif
            int effect = (int)el->car;
            if (effect < 0)
              {
#ifdef HAVE_GNUC_LABELS
                goto *se_labels[-effect];
#endif
#ifdef RX_DEBUG
                if (rx_debug_trace)
                  {
                struct rx_superset * setp = super->contents;

                fprintf (stderr, "....%d %d>> %s\n", line_no,
                     backtrack_depth,
                     efnames[-effect]);
                  }
#endif
                switch ((enum re_side_effects) effect)
                  {
                  case OF(re_se_pushback,se_pushback):
                ifr = &df->future_frame;
                if (!ifr->data)
                  {
                    struct rx_superstate * sup = super;
                    rx_lock_superstate (rx, sup);
                    if (!rx_handle_cache_miss (&rxb->rx,
                                   super, c,
                                   ifr->data_2))
                      {
                    rx_unlock_superstate (rx, sup);
                    test_ret = 0;
                    goto test_do_return;
                      }
                    rx_unlock_superstate (rx, sup);
                  }
                /* --tst_pos; */
                c = 't';
                super
                  = ((struct rx_superstate *)
                     ((char *)ifr->data
                      - (long)(((struct rx_superstate *)0)
                           ->transitions)));
                goto top_of_cycle;
                break;
                  case OF(re_se_push0,se_push0):
                {
                  struct counter_frame * old_cf
                     = (counter_stack
                    ? ((struct counter_frame *)
                       counter_stack->sp)
                    : 0);
                  struct counter_frame * cf;
                  PUSH (counter_stack,
                    sizeof (struct counter_frame));
                  cf = ((struct counter_frame *)
                    counter_stack->sp);
                  cf->tag = re_se_iter;
                  cf->val = 0;
                  cf->inherited_from = 0;
                  cf->cdr = old_cf;
                  break;
                }
                  case OF(re_se_fail,se_fail):
                goto test_do_return;
                  case OF(re_se_begbuf,se_begbuf):
                if (!AT_STRINGS_BEG ())
                  goto test_do_return;
                break;
                  case OF(re_se_endbuf,se_endbuf):
                if (!AT_STRINGS_END ())
                  goto test_do_return;
                break;
                  case OF(re_se_wordbeg,se_wordbeg):
                if (   LETTER_P (tst_pos + 1)
                    && (   AT_STRINGS_BEG()
                    || !LETTER_P (tst_pos)))
                  break;
                else
                  goto test_do_return;
                  case OF(re_se_wordend,se_wordend):
                if (   !AT_STRINGS_BEG ()
                    && LETTER_P (tst_pos)
                    && (AT_STRINGS_END ()
                    || !LETTER_P (tst_pos + 1)))
                  break;
                else
                  goto test_do_return;
                  case OF(re_se_wordbound,se_wordbound):
                if (AT_WORD_BOUNDARY (tst_pos))
                  break;
                else
                  goto test_do_return;
                  case OF(re_se_notwordbound,se_notwordbound):
                if (!AT_WORD_BOUNDARY (tst_pos))
                  break;
                else
                  goto test_do_return;
                  case OF(re_se_hat,se_hat):
                if (AT_STRINGS_BEG ())
                  {
                    if (rxb->not_bol)
                      goto test_do_return;
                    else
                      break;
                  }
                else
                  {
                    char pos_c = *tst_pos;
                    if (   (TRANSLATE (pos_c)
                        == TRANSLATE('\n'))
                    && rxb->newline_anchor)
                      break;
                    else
                      goto test_do_return;
                  }
                  case OF(re_se_dollar,se_dollar):
                if (AT_STRINGS_END ())
                  {
                    if (rxb->not_eol)
                      goto test_do_return;
                    else
                      break;
                  }
                else
                  {
                    const unsigned char * next_pos
                      = ((string2 && (tst_half == 0) &&
                      (tst_pos
                       == ((unsigned char *)
                           string1 + size1 - 1)))
                     ? (unsigned char *)string2
                     : tst_pos + 1);

                    if (   (TRANSLATE (*next_pos)
                        == TRANSLATE ('\n'))
                    && rxb->newline_anchor)
                      break;
                    else
                      goto test_do_return;
                  }

                  case OF(re_se_try,se_try):
                /* This is the first side effect in every
                 * expression.
                 *
                 *  FOR NO GOOD REASON...get rid of it...
                 */
                break;

                  case OF(re_se_pushpos,se_pushpos):
                {
                  int urhere =
                    ((int)(tst_pos - tst_str_half)
                     + ((tst_half == 0) ? 0 : size1));
                  struct counter_frame * old_cf
                    = (counter_stack
                       ? ((struct counter_frame *)
                      counter_stack->sp)
                       : 0);
                  struct counter_frame * cf;
                  PUSH(counter_stack,
                       sizeof (struct counter_frame));
                  cf = ((struct counter_frame *)
                    counter_stack->sp);
                  cf->tag = re_se_pushpos;
                  cf->val = urhere;
                  cf->inherited_from = 0;
                  cf->cdr = old_cf;
                  break;
                }

                  case OF(re_se_chkpos,se_chkpos):
                {
                  int urhere =
                    ((int)(tst_pos - tst_str_half)
                     + ((tst_half == 0) ? 0 : size1));
                  struct counter_frame * cf
                    = ((struct counter_frame *)
                       counter_stack->sp);
                  if (cf->val == urhere)
                    goto test_do_return;
                  cf->val = urhere;
                  break;
                }
                break;

                  case OF(re_se_poppos,se_poppos):
                POP(counter_stack,
                    sizeof (struct counter_frame));
                break;


                  case OF(re_se_at_dot,se_at_dot):
                  case OF(re_se_syntax,se_syntax):
                  case OF(re_se_not_syntax,se_not_syntax):
#ifdef emacs
                this release lacks emacs support;
                (coming soon);
#endif
                break;
                  case re_se_win:
                  case re_se_lparen:
                  case re_se_rparen:
                  case re_se_backref:
                  case re_se_iter:
                  case re_se_end_iter:
                  case re_se_tv:
                  case re_floogle_flap:
                ret_val = 0;
                goto test_do_return;
                  }
              }
            else
              {
#ifdef HAVE_GNUC_LABELS
                goto *se_lables2[(rxb->se_params [effect].se)];
#endif
#ifdef RX_DEBUG
              if (rx_debug_trace)
                fprintf (stderr, "....%d %d>> %s %d %d\n", line_no,
                     backtrack_depth,
                     efnames2[rxb->se_params [effect].se],
                     rxb->se_params [effect].op1,
                     rxb->se_params [effect].op2);
#endif
                switch (rxb->se_params [effect].se)
                  {
                  case OF(re_se_win,se_win):
                /* This side effect indicates that we've
                 * found a match, though not necessarily the
                 * best match.  This is a fancy assignment to
                 * register 0 unless the caller didn't
                 * care about registers.  In which case,
                 * this stops the match.
                 */
                {
                  int urhere =
                    ((int)(tst_pos - tst_str_half)
                     + ((tst_half == 0)
                    ? 0 : size1));

                  if (   (best_last_r < 0)
                      || (urhere + 1 > best_rparen[0]))
                    {
                      /* Record the best known and keep
                       * looking.
                       */
                      int x;
                      for (x = 0; x <= last_l; ++x)
                    best_lparen[x] = lparen[x];
                      best_last_l = last_l;
                      for (x = 0; x <= last_r; ++x)
                    best_rparen[x] = rparen[x];
                      best_rparen[0] = urhere + 1;
                      best_last_r = last_r;
                    }
                  /* If we're not reporting the match-length
                   * or other register info, we need look no
                   * further.
                   */
                  if (first_found)
                    {
                      test_ret = -2;
                      goto test_do_return;
                    }
                }
                break;
                  case OF(re_se_lparen,se_lparen):
                {
                  int urhere =
                    ((int)(tst_pos - tst_str_half)
                     + ((tst_half == 0) ? 0 : size1));

                  int reg = rxb->se_params [effect].op1;
#if 0
                  if (reg > last_l)
#endif
                    {
                      lparen[reg] = urhere + 1;
                      /* In addition to making this assignment,
                       * we now know that lower numbered regs
                       * that haven't already been assigned,
                       * won't be.  We make sure they're
                       * filled with -1, so they can be
                       * recognized as unassigned.
                       */
                      if (last_l < reg)
                    while (++last_l < reg)
                      lparen[last_l] = -1;
                    }
                  break;
                }

                  case OF(re_se_rparen,se_rparen):
                {
                  int urhere =
                    ((int)(tst_pos - tst_str_half)
                     + ((tst_half == 0) ? 0 : size1));
                  int reg = rxb->se_params [effect].op1;
                  rparen[reg] = urhere + 1;
                  if (last_r < reg)
                    {
                      while (++last_r < reg)
                    rparen[last_r] = -1;
                    }
                  break;
                }

                  case OF(re_se_backref,se_backref):
                {
                  int reg = rxb->se_params [effect].op1;
                  if (reg > last_r || rparen[reg] < 0)
                    goto test_do_return;
                  {
                    /* fixme */
                    const unsigned char * there
                      = tst_str_half + lparen[reg];
                    const unsigned char * last
                      = tst_str_half + rparen[reg];
                    const unsigned char * here = tst_pos + 1;

                    if ((here == tst_end_half) && string2
                    && (tst_str_half
                        == (unsigned char *) string1)
                    && (tst_end_half != abs_end))
                      {
                    here = (unsigned char *)string2;
                    tst_end_half = abs_end;
                      }

                    while (there < last && here < tst_end_half)    /* 4% */
                      if (TRANSLATE(*there) /* &&&& 6% */
                      != TRANSLATE(*here))
                    goto test_do_return;
                      else
                    {
                      ++there; ++here;
                      if ((here == tst_end_half) && string2
                          && (tst_str_half
                          == (unsigned char *)string1)
                          && (tst_end_half != abs_end))
                        {
                          here = (unsigned char *)string2;
                          tst_end_half = abs_end;
                          tst_half = 1;
                        }
                    }
                    if (there != last)
                      goto test_do_return;
                    tst_pos = here - 1;
                    if ((here == (unsigned char *)string2)
                    && (unsigned char *)string1)
                      {
                    tst_pos = ((unsigned char *)string1
                           + size1 - 1);
                    tst_end_half = tst_pos + 1;
                    tst_half = 0;
                      }
                  }
                  break;
                }
                  case OF(re_se_iter,se_iter):
                {
                  struct counter_frame * csp
                    = ((struct counter_frame *)
                       counter_stack->sp);
                  if (csp->val == rxb->se_params[effect].op2)
                    goto test_do_return;
                  else
                    ++csp->val;
                  break;
                }
                  case OF(re_se_end_iter,se_end_iter):
                {
                  struct counter_frame * csp
                    = ((struct counter_frame *)
                       counter_stack->sp);
                  if (csp->val < rxb->se_params[effect].op1)
                    goto test_do_return;
                  else
                    {
                      struct counter_frame * source = csp;
                      while (source->inherited_from)
                    source = source->inherited_from;
                      if (!source || !source->cdr)
                    {
                      POP(counter_stack,
                          sizeof(struct counter_frame));
                    }
                      else
                    {
                      source = source->cdr;
                      csp->val = source->val;
                      csp->tag = source->tag;
                      csp->cdr = 0;
                      csp->inherited_from = source;
                    }
                    }
                  break;
                }
                  case OF(re_se_tv, se_tv):
                /* is a noop */
                break;
                  case re_se_try:
                  case re_se_pushback:
                  case re_se_push0:
                  case re_se_pushpos:
                  case re_se_chkpos:
                  case re_se_poppos:
                  case re_se_at_dot:
                  case re_se_syntax:
                  case re_se_not_syntax:
                  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_floogle_flap:
                ret_val = 0;
                goto test_do_return;
                  }
              }
            el = el->cdr;
              }
            /* Now the side effects are done,
             * so get the next instruction.
             * and move on.
             */
            ifr = &df->future_frame;
            goto restart;
          }

        case OF(rx_backtrack_point,backtrack_point):
          {
            /* A backtrack point indicates that we've reached a
             * non-determinism in the superstate NFA.  This is a
             * loop that exhaustively searches the possibilities.
             *
             * A backtracking strategy is used.  We keep track of what
             * registers are valid so we can erase side effects.
             *
             * First, make sure there is some stack space to hold
             * our state.
             */

            struct backtrack_frame * bf;

            PUSH(backtrack_stack, backtrack_frame_bytes);
#ifdef RX_DEBUG
            ++backtrack_depth;
#endif

            bf = ((struct backtrack_frame *)
              backtrack_stack->sp);
            {
              bf->stk_super = super;
              /* We prevent the current superstate from being
               * deleted from the superstate cache.
               */
              rx_lock_superstate (&rxb->rx, super);
              bf->stk_tst_pos = tst_pos;
#ifdef RX_DEBUG
              bf->stk_line_no = line_no;
#endif
              bf->stk_tst_half = tst_half;
              bf->stk_c = c;
              bf->stk_tst_str_half = tst_str_half;
              bf->stk_tst_end_half = tst_end_half;
              bf->stk_last_l = last_l;
              bf->stk_last_r = last_r;
              bf->df = ((struct rx_super_edge *)ifr->data_2)->options;
              bf->first_df = bf->df;
              bf->counter_stack_sp = (counter_stack
                          ? counter_stack->sp
                          : 0);
              bf->stk_test_ret = test_ret;
              if (rxb->match_regs_on_stack)
            {
              int x;
              regoff_t * stk =
                (regoff_t *)((char *)bf + sizeof (*bf));
              for (x = 0; x <= last_l; ++x)
                stk[x] = lparen[x];
              stk += x;
              for (x = 0; x <= last_r; ++x)
                stk[x] = rparen[x];
            }

            }

            /* Here is a while loop whose body is mainly a function
             * call and some code to handle a return from that
             * function.
             *
             * From here on for the rest of `case backtrack_point' it
             * is unsafe to assume that the variables saved on the
             * stack are valid -- so reread their values from the stack
             * as needed.
             *
             * This lets us re-use one generation fewer stack saves in
             * the call-graph of a search.
             */

          while_non_det_options:
#ifdef RX_DEBUG
            ++lines_found;
            if (rx_debug_trace)
              fprintf (stderr, "@@@ %d calls %d @@@\n",
                   line_no, lines_found);

            line_no = lines_found;
#endif

            if (bf->df->next_same_super_edge[0] == bf->first_df)
              {
            /* This is a tail-call optimization -- we don't recurse
             * for the last of the possible futures.
             */
            ifr = (bf->df->effects
                   ? &bf->df->side_effects_frame
                   : &bf->df->future_frame);

            rx_unlock_superstate (&rxb->rx, super);
            POP(backtrack_stack, backtrack_frame_bytes);
#ifdef RX_DEBUG
            --backtrack_depth;
#endif
            goto restart;
              }
            else
              {
            if (counter_stack)
              {
                struct counter_frame * old_cf
                  = ((struct counter_frame *)counter_stack->sp);
                struct counter_frame * cf;
                PUSH(counter_stack, sizeof (struct counter_frame));
                cf = ((struct counter_frame *)counter_stack->sp);
                cf->tag = old_cf->tag;
                cf->val = old_cf->val;
                cf->inherited_from = old_cf;
                cf->cdr = 0;
              }
            /* `Call' this test-match block */
            ifr = (bf->df->effects
                   ? &bf->df->side_effects_frame
                   : &bf->df->future_frame);
            goto recurse_test_match;
              }

            /* Returns in this block are accomplished by
             * goto test_do_return.  There are two cases.
             * If there is some search-stack left,
             * then it is a return from a `recursive' call.
             * If there is no search-stack left, then
             * we should return to the fastmap/search loop.
             */

          test_do_return:

            if (!backtrack_stack)
              {
#ifdef RX_DEBUG
            if (rx_debug_trace)
              fprintf (stderr, "!!! %d bails returning %d !!!\n",
                   line_no, test_ret);
#endif

            /* No more search-stack -- this test is done. */
            if (test_ret)
              goto return_from_test_match;
            else
              goto error_in_testing_match;
              }

            /* Ok..we're returning from a recursive call to
             * the test match block:
             */

            bf = ((struct backtrack_frame *)
              backtrack_stack->sp);
#ifdef RX_DEBUG
            if (rx_debug_trace)
              fprintf (stderr, "+++ %d returns %d (to %d)+++\n",
                   line_no, test_ret, bf->stk_line_no);
#endif

            while (counter_stack
               && (!bf->counter_stack_sp
                   || (bf->counter_stack_sp != counter_stack->sp)))
              {
            POP(counter_stack, sizeof (struct counter_frame));
              }

            if (!test_ret)
              {
            POP (backtrack_stack, backtrack_frame_bytes);
            goto test_do_return;
              }

            /* If any possible future reaches the end of the
             * string without failing, make sure we propogate
             * that information to the caller.
             */
            if ((test_ret == -2) && first_found)
              {
            rx_unlock_superstate (&rxb->rx, bf->stk_super);
            POP (backtrack_stack, backtrack_frame_bytes);
            goto test_do_return;
              }

            if (bf->stk_test_ret < 0)
              test_ret = bf->stk_test_ret;

            last_l = bf->stk_last_l;
            last_r = bf->stk_last_r;
            bf->df = bf->df->next_same_super_edge[0];
            super = bf->stk_super;
            tst_pos = bf->stk_tst_pos;
            tst_half = bf->stk_tst_half;
            c = bf->stk_c;
            tst_str_half = bf->stk_tst_str_half;
            tst_end_half = bf->stk_tst_end_half;
#ifdef RX_DEBUG
            line_no = bf->stk_line_no;
#endif

            if (rxb->match_regs_on_stack)
              {
            int x;
            regoff_t * stk =
              (regoff_t *)((char *)bf + sizeof (*bf));
            for (x = 0; x <= last_l; ++x)
              lparen[x] = stk[x];
            stk += x;
            for (x = 0; x <= last_r; ++x)
              rparen[x] = stk[x];
              }

            goto while_non_det_options;
          }


        case OF(rx_cache_miss,cache_miss):
          /* Because the superstate NFA is lazily constructed,
           * and in fact may erode from underneath us, we sometimes
           * have to construct the next instruction from the hard way.
           * This invokes one step in the lazy-conversion.
           */
          ifr = rx_handle_cache_miss (&rxb->rx, super, c, ifr->data_2);
          if (!ifr)
            {
              test_ret = 0;
              goto test_do_return;
            }
          goto restart;

        case OF(rx_backtrack,backtrack):
          /* RX_BACKTRACK means that we've reached the empty
           * superstate, indicating that match can't succeed
           * from this point.
           */
          goto test_do_return;
        case rx_next_char:
        case rx_error_inx:
        case rx_num_instructions:
          ret_val = 0;
          goto test_do_return;
        }
        }
    }


    /* Healthy exists from the test-match loop do a
     * `goto return_from_test_match'   On the other hand,
     * we might end up here.
     */
      error_in_testing_match:
    ret_val = -2;
    goto finish;


    /***** fastmap/search loop body
     *          considering the results testing for a match
     */

      return_from_test_match:

    if (best_last_l >= 0)
      {
        if (regs && (regs->start != best_lparen))
          {
        bcopy (best_lparen, regs->start,
               regs->num_regs * sizeof (int));
        bcopy (best_rparen, regs->end,
               regs->num_regs * sizeof (int));
          }
        if (regs && !rxb->no_sub)
          {
        int q;
        int bound = (regs->num_regs > num_regs
                 ? regs->num_regs
                 : num_regs);
        regoff_t * s = regs->start;
        regoff_t * e = regs->end;
        for (q = best_last_l + 1;  q < bound; ++q)
          s[q] = e[q] = -1;
          }
        ret_val = best_lparen[0];
        goto finish;
      }

    /***** fastmap/search loop,  increment and loop-test */

    pos += search_direction;
    startpos += search_direction;

      } while (startpos < search_end);


  /**** Exit code for fastmap/searchloop and the entire re_search_2 fn. */

  finish:
    /* Unset the fastmap sentinel */
    if (fastmap_chr >= 0)
      fastmap[fastmap_chr] = fastmap_val;

    if (start_super)
      rx_unlock_superstate (&rxb->rx, start_super);

#ifdef REGEX_MALLOC
    if (lparen) free (lparen);
    if (rparen) free (rparen);
    if (best_lpspace) free (best_lpspace);AT_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->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 = TALLOC (nmatch, regoff_t);
      regs.end = TALLOC (nmatch, 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 ? ®s : (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  */