initial check-in, version 0.5.0 v0.5.0

1 files changed, 3362 insertions, 0 deletions

diff --git a/src/regex/regcomp.c b/src/regex/regcomp.c
new file mode 100644
index 00000000..3307942e
--- /dev/null
+++ b/src/regex/regcomp.c
@@ -0,0 +1,3362 @@
+/*
+  regcomp.c - TRE POSIX compatible regex compilation functions.
+
+  Copyright (c) 2001-2006 Ville Laurikari <vl@iki.fi>
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <regex.h>
+#include <limits.h>
+#include <stdint.h>
+
+#include "tre.h"
+
+#include <assert.h>
+
+/***********************************************************************
+ from tre-ast.c and tre-ast.h
+***********************************************************************/
+
+/* The different AST node types. */
+typedef enum {
+  LITERAL,
+  CATENATION,
+  ITERATION,
+  UNION
+} tre_ast_type_t;
+
+/* Special subtypes of TRE_LITERAL. */
+#define EMPTY	  -1   /* Empty leaf (denotes empty string). */
+#define ASSERTION -2   /* Assertion leaf. */
+#define TAG	  -3   /* Tag leaf. */
+#define BACKREF	  -4   /* Back reference leaf. */
+
+#define IS_SPECIAL(x)	((x)->code_min < 0)
+#define IS_EMPTY(x)	((x)->code_min == EMPTY)
+#define IS_ASSERTION(x) ((x)->code_min == ASSERTION)
+#define IS_TAG(x)	((x)->code_min == TAG)
+#define IS_BACKREF(x)	((x)->code_min == BACKREF)
+
+/* Taken from tre-compile.h */
+typedef struct {
+  int position;
+  int code_min;
+  int code_max;
+  int *tags;
+  int assertions;
+  tre_ctype_t class;
+  tre_ctype_t *neg_classes;
+  int backref;
+} tre_pos_and_tags_t;
+
+/* A generic AST node.  All AST nodes consist of this node on the top
+   level with `obj' pointing to the actual content. */
+typedef struct {
+  tre_ast_type_t type;   /* Type of the node. */
+  void *obj;             /* Pointer to actual node. */
+  int nullable;
+  int submatch_id;
+  int num_submatches;
+  int num_tags;
+  tre_pos_and_tags_t *firstpos;
+  tre_pos_and_tags_t *lastpos;
+} tre_ast_node_t;
+
+
+/* A "literal" node.  These are created for assertions, back references,
+   tags, matching parameter settings, and all expressions that match one
+   character. */
+typedef struct {
+  long code_min;
+  long code_max;
+  int position;
+  tre_ctype_t class;
+  tre_ctype_t *neg_classes;
+} tre_literal_t;
+
+/* A "catenation" node.	 These are created when two regexps are concatenated.
+   If there are more than one subexpressions in sequence, the `left' part
+   holds all but the last, and `right' part holds the last subexpression
+   (catenation is left associative). */
+typedef struct {
+  tre_ast_node_t *left;
+  tre_ast_node_t *right;
+} tre_catenation_t;
+
+/* An "iteration" node.	 These are created for the "*", "+", "?", and "{m,n}"
+   operators. */
+typedef struct {
+  /* Subexpression to match. */
+  tre_ast_node_t *arg;
+  /* Minimum number of consecutive matches. */
+  int min;
+  /* Maximum number of consecutive matches. */
+  int max;
+} tre_iteration_t;
+
+/* An "union" node.  These are created for the "|" operator. */
+typedef struct {
+  tre_ast_node_t *left;
+  tre_ast_node_t *right;
+} tre_union_t;
+
+static tre_ast_node_t *
+tre_ast_new_node(tre_mem_t mem, tre_ast_type_t type, size_t size)
+{
+  tre_ast_node_t *node;
+
+  node = tre_mem_calloc(mem, sizeof(*node));
+  if (!node)
+    return NULL;
+  node->obj = tre_mem_calloc(mem, size);
+  if (!node->obj)
+    return NULL;
+  node->type = type;
+  node->nullable = -1;
+  node->submatch_id = -1;
+
+  return node;
+}
+
+static tre_ast_node_t *
+tre_ast_new_literal(tre_mem_t mem, int code_min, int code_max, int position)
+{
+  tre_ast_node_t *node;
+  tre_literal_t *lit;
+
+  node = tre_ast_new_node(mem, LITERAL, sizeof(tre_literal_t));
+  if (!node)
+    return NULL;
+  lit = node->obj;
+  lit->code_min = code_min;
+  lit->code_max = code_max;
+  lit->position = position;
+
+  return node;
+}
+
+static tre_ast_node_t *
+tre_ast_new_iter(tre_mem_t mem, tre_ast_node_t *arg, int min, int max)
+{
+  tre_ast_node_t *node;
+  tre_iteration_t *iter;
+
+  node = tre_ast_new_node(mem, ITERATION, sizeof(tre_iteration_t));
+  if (!node)
+    return NULL;
+  iter = node->obj;
+  iter->arg = arg;
+  iter->min = min;
+  iter->max = max;
+  node->num_submatches = arg->num_submatches;
+
+  return node;
+}
+
+static tre_ast_node_t *
+tre_ast_new_union(tre_mem_t mem, tre_ast_node_t *left, tre_ast_node_t *right)
+{
+  tre_ast_node_t *node;
+
+  node = tre_ast_new_node(mem, UNION, sizeof(tre_union_t));
+  if (node == NULL)
+    return NULL;
+  ((tre_union_t *)node->obj)->left = left;
+  ((tre_union_t *)node->obj)->right = right;
+  node->num_submatches = left->num_submatches + right->num_submatches;
+
+  return node;
+}
+
+static tre_ast_node_t *
+tre_ast_new_catenation(tre_mem_t mem, tre_ast_node_t *left,
+		       tre_ast_node_t *right)
+{
+  tre_ast_node_t *node;
+
+  node = tre_ast_new_node(mem, CATENATION, sizeof(tre_catenation_t));
+  if (node == NULL)
+    return NULL;
+  ((tre_catenation_t *)node->obj)->left = left;
+  ((tre_catenation_t *)node->obj)->right = right;
+  node->num_submatches = left->num_submatches + right->num_submatches;
+
+  return node;
+}
+
+/***********************************************************************
+ from tre-stack.c and tre-stack.h
+***********************************************************************/
+
+/* Just to save some typing. */
+#define STACK_PUSH(s, value)						      \
+  do									      \
+    {									      \
+      status = tre_stack_push(s, (void *)(value));			      \
+    }									      \
+  while (0)
+
+#define STACK_PUSHX(s, value)						      \
+  {									      \
+    status = tre_stack_push(s, (void *)(value));			      \
+    if (status != REG_OK)						      \
+      break;								      \
+  }
+
+#define STACK_PUSHR(s, value)						      \
+  {									      \
+    reg_errcode_t status;						      \
+    status = tre_stack_push(s, (void *)(value));			      \
+    if (status != REG_OK)						      \
+      return status;							      \
+  }
+
+typedef struct tre_stack_rec {
+  int size;
+  int max_size;
+  int increment;
+  int ptr;
+  void **stack;
+} tre_stack_t;
+
+
+static tre_stack_t *
+tre_stack_new(int size, int max_size, int increment)
+{
+  tre_stack_t *s;
+
+  s = xmalloc(sizeof(*s));
+  if (s != NULL)
+    {
+      s->stack = xmalloc(sizeof(*s->stack) * size);
+      if (s->stack == NULL)
+	{
+	  xfree(s);
+	  return NULL;
+	}
+      s->size = size;
+      s->max_size = max_size;
+      s->increment = increment;
+      s->ptr = 0;
+    }
+  return s;
+}
+
+static void
+tre_stack_destroy(tre_stack_t *s)
+{
+  xfree(s->stack);
+  xfree(s);
+}
+
+static int
+tre_stack_num_objects(tre_stack_t *s)
+{
+  return s->ptr;
+}
+
+static reg_errcode_t
+tre_stack_push(tre_stack_t *s, void *value)
+{
+  if (s->ptr < s->size)
+    {
+      s->stack[s->ptr] = value;
+      s->ptr++;
+    }
+  else
+    {
+      if (s->size >= s->max_size)
+	{
+	  DPRINT(("tre_stack_push: stack full\n"));
+	  return REG_ESPACE;
+	}
+      else
+	{
+	  void **new_buffer;
+	  int new_size;
+	  DPRINT(("tre_stack_push: trying to realloc more space\n"));
+	  new_size = s->size + s->increment;
+	  if (new_size > s->max_size)
+	    new_size = s->max_size;
+	  new_buffer = xrealloc(s->stack, sizeof(*new_buffer) * new_size);
+	  if (new_buffer == NULL)
+	    {
+	      DPRINT(("tre_stack_push: realloc failed.\n"));
+	      return REG_ESPACE;
+	    }
+	  DPRINT(("tre_stack_push: realloc succeeded.\n"));
+	  assert(new_size > s->size);
+	  s->size = new_size;
+	  s->stack = new_buffer;
+	  tre_stack_push(s, value);
+	}
+    }
+  return REG_OK;
+}
+
+static void *
+tre_stack_pop(tre_stack_t *s)
+{
+  return s->stack[--s->ptr];
+}
+
+
+/***********************************************************************
+ from tre-parse.c and tre-parse.h
+***********************************************************************/
+
+/* Parse context. */
+typedef struct {
+  /* Memory allocator.	The AST is allocated using this. */
+  tre_mem_t mem;
+  /* Stack used for keeping track of regexp syntax. */
+  tre_stack_t *stack;
+  /* The parse result. */
+  tre_ast_node_t *result;
+  /* The regexp to parse and its length. */
+  const tre_char_t *re;
+  /* The first character of the entire regexp. */
+  const tre_char_t *re_start;
+  /* The first character after the end of the regexp. */
+  const tre_char_t *re_end;
+  int len;
+  /* Current submatch ID. */
+  int submatch_id;
+  /* Current position (number of literal). */
+  int position;
+  /* The highest back reference or -1 if none seen so far. */
+  int max_backref;
+  /* Compilation flags. */
+  int cflags;
+  /* If this flag is set the top-level submatch is not captured. */
+  int nofirstsub;
+} tre_parse_ctx_t;
+
+static reg_errcode_t
+tre_new_item(tre_mem_t mem, int min, int max, int *i, int *max_i,
+	 tre_ast_node_t ***items)
+{
+  reg_errcode_t status;
+  tre_ast_node_t **array = *items;
+  /* Allocate more space if necessary. */
+  if (*i >= *max_i)
+    {
+      tre_ast_node_t **new_items;
+      DPRINT(("out of array space, i = %d\n", *i));
+      /* If the array is already 1024 items large, give up -- there's
+	 probably an error in the regexp (e.g. not a '\0' terminated
+	 string and missing ']') */
+      if (*max_i > 1024)
+	return REG_ESPACE;
+      *max_i *= 2;
+      new_items = xrealloc(array, sizeof(*items) * *max_i);
+      if (new_items == NULL)
+	return REG_ESPACE;
+      *items = array = new_items;
+    }
+  array[*i] = tre_ast_new_literal(mem, min, max, -1);
+  status = array[*i] == NULL ? REG_ESPACE : REG_OK;
+  (*i)++;
+  return status;
+}
+
+
+/* Expands a character class to character ranges. */
+static reg_errcode_t
+tre_expand_ctype(tre_mem_t mem, tre_ctype_t class, tre_ast_node_t ***items,
+		 int *i, int *max_i, int cflags)
+{
+  reg_errcode_t status = REG_OK;
+  tre_cint_t c;
+  int j, min = -1, max = 0;
+  assert(TRE_MB_CUR_MAX == 1);
+
+  DPRINT(("  expanding class to character ranges\n"));
+  for (j = 0; (j < 256) && (status == REG_OK); j++)
+    {
+      c = j;
+      if (tre_isctype(c, class)
+	  || ((cflags & REG_ICASE)
+	      && (tre_isctype(tre_tolower(c), class)
+		  || tre_isctype(tre_toupper(c), class))))
+{
+	  if (min < 0)
+	    min = c;
+	  max = c;
+	}
+      else if (min >= 0)
+	{
+	  DPRINT(("  range %c (%d) to %c (%d)\n", min, min, max, max));
+	  status = tre_new_item(mem, min, max, i, max_i, items);
+	  min = -1;
+	}
+    }
+  if (min >= 0 && status == REG_OK)
+    status = tre_new_item(mem, min, max, i, max_i, items);
+  return status;
+}
+
+
+static int
+tre_compare_items(const void *a, const void *b)
+{
+  tre_ast_node_t *node_a = *(tre_ast_node_t **)a;
+  tre_ast_node_t *node_b = *(tre_ast_node_t **)b;
+  tre_literal_t *l_a = node_a->obj, *l_b = node_b->obj;
+  int a_min = l_a->code_min, b_min = l_b->code_min;
+
+  if (a_min < b_min)
+    return -1;
+  else if (a_min > b_min)
+    return 1;
+  else
+    return 0;
+}
+
+/* Maximum number of character classes that can occur in a negated bracket
+   expression.	*/
+#define MAX_NEG_CLASSES 64
+
+/* Maximum length of character class names. */
+#define MAX_CLASS_NAME
+
+static reg_errcode_t
+tre_parse_bracket_items(tre_parse_ctx_t *ctx, int negate,
+			tre_ctype_t neg_classes[], int *num_neg_classes,
+			tre_ast_node_t ***items, int *num_items,
+			int *items_size)
+{
+  const tre_char_t *re = ctx->re;
+  reg_errcode_t status = REG_OK;
+  tre_ctype_t class = (tre_ctype_t)0;
+  int i = *num_items;
+  int max_i = *items_size;
+  int skip;
+
+  /* Build an array of the items in the bracket expression. */
+  while (status == REG_OK)
+    {
+      skip = 0;
+      if (re == ctx->re_end)
+	{
+	  status = REG_EBRACK;
+	}
+      else if (*re == ']' && re > ctx->re)
+	{
+	  DPRINT(("tre_parse_bracket:	done: '%.*" STRF "'\n",
+		  ctx->re_end - re, re));
+	  re++;
+	  break;
+	}
+      else
+	{
+	  tre_cint_t min = 0, max = 0;
+
+	  class = (tre_ctype_t)0;
+	  if (re + 2 < ctx->re_end
+	      && *(re + 1) == '-' && *(re + 2) != ']')
+	    {
+	      DPRINT(("tre_parse_bracket:  range: '%.*" STRF "'\n",
+		      ctx->re_end - re, re));
+	      min = *re;
+	      max = *(re + 2);
+	      re += 3;
+	      /* XXX - Should use collation order instead of encoding values
+		 in character ranges. */
+	      if (min > max)
+		status = REG_ERANGE;
+	    }
+	  else if (re + 1 < ctx->re_end
+		   && *re == '[' && *(re + 1) == '.')
+	    status = REG_ECOLLATE;
+	  else if (re + 1 < ctx->re_end
+		   && *re == '[' && *(re + 1) == '=')
+	    status = REG_ECOLLATE;
+	  else if (re + 1 < ctx->re_end
+		   && *re == '[' && *(re + 1) == ':')
+	    {
+	      char tmp_str[64];
+	      const tre_char_t *endptr = re + 2;
+	      int len;
+	      DPRINT(("tre_parse_bracket:  class: '%.*" STRF "'\n",
+		      ctx->re_end - re, re));
+	      while (endptr < ctx->re_end && *endptr != ':')
+		endptr++;
+	      if (endptr != ctx->re_end)
+		{
+		  len = MIN(endptr - re - 2, 63);
+#ifdef TRE_WCHAR
+		  {
+		    tre_char_t tmp_wcs[64];
+		    wcsncpy(tmp_wcs, re + 2, len);
+		    tmp_wcs[len] = '\0';
+#if defined HAVE_WCSRTOMBS
+		    {
+		      mbstate_t state;
+		      const tre_char_t *src = tmp_wcs;
+		      memset(&state, '\0', sizeof(state));
+		      len = wcsrtombs(tmp_str, &src, sizeof(tmp_str), &state);
+		    }
+#elif defined HAVE_WCSTOMBS
+		    len = wcstombs(tmp_str, tmp_wcs, 63);
+#endif /* defined HAVE_WCSTOMBS */
+		  }
+#else /* !TRE_WCHAR */
+		  strncpy(tmp_str, re + 2, len);
+#endif /* !TRE_WCHAR */
+		  tmp_str[len] = '\0';
+		  DPRINT(("  class name: %s\n", tmp_str));
+		  class = tre_ctype(tmp_str);
+		  if (!class)
+		    status = REG_ECTYPE;
+		  /* Optimize character classes for 8 bit character sets. */
+		  if (status == REG_OK && TRE_MB_CUR_MAX == 1)
+		    {
+		      status = tre_expand_ctype(ctx->mem, class, items,
+						&i, &max_i, ctx->cflags);
+		      class = (tre_ctype_t)0;
+		      skip = 1;
+		    }
+		  re = endptr + 2;
+		}
+	      else
+		status = REG_ECTYPE;
+	      min = 0;
+	      max = TRE_CHAR_MAX;
+	    }
+	  else
+	    {
+	      DPRINT(("tre_parse_bracket:   char: '%.*" STRF "'\n",
+		      ctx->re_end - re, re));
+	      if (*re == '-' && *(re + 1) != ']'
+		  && ctx->re != re)
+		/* Two ranges are not allowed to share and endpoint. */
+		status = REG_ERANGE;
+	      min = max = *re++;
+	    }
+
+	  if (status != REG_OK)
+	    break;
+
+	  if (class && negate)
+	    if (*num_neg_classes >= MAX_NEG_CLASSES)
+	      status = REG_ESPACE;
+	    else
+	      neg_classes[(*num_neg_classes)++] = class;
+	  else if (!skip)
+	    {
+	      status = tre_new_item(ctx->mem, min, max, &i, &max_i, items);
+	      if (status != REG_OK)
+		break;
+	      ((tre_literal_t*)((*items)[i-1])->obj)->class = class;
+	    }
+
+	  /* Add opposite-case counterpoints if REG_ICASE is present.
+	     This is broken if there are more than two "same" characters. */
+	  if (ctx->cflags & REG_ICASE && !class && status == REG_OK && !skip)
+	    {
+	      int cmin, ccurr;
+
+	      DPRINT(("adding opposite-case counterpoints\n"));
+	      while (min <= max)
+		{
+		  if (tre_islower(min))
+		    {
+		      cmin = ccurr = tre_toupper(min++);
+		      while (tre_islower(min) && tre_toupper(min) == ccurr + 1
+			     && min <= max)
+			ccurr = tre_toupper(min++);
+		      status = tre_new_item(ctx->mem, cmin, ccurr,
+					    &i, &max_i, items);
+		    }
+		  else if (tre_isupper(min))
+		    {
+		      cmin = ccurr = tre_tolower(min++);
+		      while (tre_isupper(min) && tre_tolower(min) == ccurr + 1
+			     && min <= max)
+			ccurr = tre_tolower(min++);
+		      status = tre_new_item(ctx->mem, cmin, ccurr,
+					    &i, &max_i, items);
+		    }
+		  else min++;
+		  if (status != REG_OK)
+		    break;
+		}
+	      if (status != REG_OK)
+		break;
+	    }
+	}
+    }
+  *num_items = i;
+  *items_size = max_i;
+  ctx->re = re;
+  return status;
+}
+
+static reg_errcode_t
+tre_parse_bracket(tre_parse_ctx_t *ctx, tre_ast_node_t **result)
+{
+  tre_ast_node_t *node = NULL;
+  int negate = 0;
+  reg_errcode_t status = REG_OK;
+  tre_ast_node_t **items, *u, *n;
+  int i = 0, j, max_i = 32, curr_max, curr_min;
+  tre_ctype_t neg_classes[MAX_NEG_CLASSES];
+  int num_neg_classes = 0;
+
+  /* Start off with an array of `max_i' elements. */
+  items = xmalloc(sizeof(*items) * max_i);
+  if (items == NULL)
+    return REG_ESPACE;
+
+  if (*ctx->re == '^')
+    {
+      DPRINT(("tre_parse_bracket: negate: '%.*" STRF "'\n",
+	      ctx->re_end - ctx->re, ctx->re));
+      negate = 1;
+      ctx->re++;
+    }
+
+  status = tre_parse_bracket_items(ctx, negate, neg_classes, &num_neg_classes,
+				   &items, &i, &max_i);
+
+  if (status != REG_OK)
+    goto parse_bracket_done;
+
+  /* Sort the array if we need to negate it. */
+  if (negate)
+    qsort(items, i, sizeof(*items), tre_compare_items);
+
+  curr_max = curr_min = 0;
+  /* Build a union of the items in the array, negated if necessary. */
+  for (j = 0; j < i && status == REG_OK; j++)
+    {
+      int min, max;
+      tre_literal_t *l = items[j]->obj;
+      min = l->code_min;
+      max = l->code_max;
+
+      DPRINT(("item: %d - %d, class %ld, curr_max = %d\n",
+	      (int)l->code_min, (int)l->code_max, (long)l->class, curr_max));
+
+      if (negate)
+	{
+	  if (min < curr_max)
+	    {
+	      /* Overlap. */
+	      curr_max = MAX(max + 1, curr_max);
+	      DPRINT(("overlap, curr_max = %d\n", curr_max));
+	      l = NULL;
+	    }
+	  else
+	    {
+	      /* No overlap. */
+	      curr_max = min - 1;
+	      if (curr_max >= curr_min)
+		{
+		  DPRINT(("no overlap\n"));
+		  l->code_min = curr_min;
+		  l->code_max = curr_max;
+		}
+	      else
+		{
+		  DPRINT(("no overlap, zero room\n"));
+		  l = NULL;
+		}
+	      curr_min = curr_max = max + 1;
+	    }
+	}
+
+      if (l != NULL)
+	{
+	  int k;
+	  DPRINT(("creating %d - %d\n", (int)l->code_min, (int)l->code_max));
+	  l->position = ctx->position;
+	  if (num_neg_classes > 0)
+	    {
+	      l->neg_classes = tre_mem_alloc(ctx->mem,
+					     (sizeof(l->neg_classes)
+					      * (num_neg_classes + 1)));
+	      if (l->neg_classes == NULL)
+		{
+		  status = REG_ESPACE;
+		  break;
+		}
+	      for (k = 0; k < num_neg_classes; k++)
+		l->neg_classes[k] = neg_classes[k];
+	      l->neg_classes[k] = (tre_ctype_t)0;
+	    }
+	  else
+	    l->neg_classes = NULL;
+	  if (node == NULL)
+	    node = items[j];
+	  else
+	    {
+	      u = tre_ast_new_union(ctx->mem, node, items[j]);
+	      if (u == NULL)
+		status = REG_ESPACE;
+	      node = u;
+	    }
+	}
+    }
+
+  if (status != REG_OK)
+    goto parse_bracket_done;
+
+  if (negate)
+    {
+      int k;
+      DPRINT(("final: creating %d - %d\n", curr_min, (int)TRE_CHAR_MAX));
+      n = tre_ast_new_literal(ctx->mem, curr_min, TRE_CHAR_MAX, ctx->position);
+      if (n == NULL)
+	status = REG_ESPACE;
+      else
+	{
+	  tre_literal_t *l = n->obj;
+	  if (num_neg_classes > 0)
+	    {
+	      l->neg_classes = tre_mem_alloc(ctx->mem,
+					     (sizeof(l->neg_classes)
+					      * (num_neg_classes + 1)));
+	      if (l->neg_classes == NULL)
+		{
+		  status = REG_ESPACE;
+		  goto parse_bracket_done;
+		}
+	      for (k = 0; k < num_neg_classes; k++)
+		l->neg_classes[k] = neg_classes[k];
+	      l->neg_classes[k] = (tre_ctype_t)0;
+	    }
+	  else
+	    l->neg_classes = NULL;
+	  if (node == NULL)
+	    node = n;
+	  else
+	    {
+	      u = tre_ast_new_union(ctx->mem, node, n);
+	      if (u == NULL)
+		status = REG_ESPACE;
+	      node = u;
+	    }
+	}
+    }
+
+  if (status != REG_OK)
+    goto parse_bracket_done;
+
+#ifdef TRE_DEBUG
+  tre_ast_print(node);
+#endif /* TRE_DEBUG */
+
+ parse_bracket_done:
+  xfree(items);
+  ctx->position++;
+  *result = node;
+  return status;
+}
+
+
+/* Parses a positive decimal integer.  Returns -1 if the string does not
+   contain a valid number. */
+static int
+tre_parse_int(const tre_char_t **regex, const tre_char_t *regex_end)
+{
+  int num = -1;
+  const tre_char_t *r = *regex;
+  while (r < regex_end && *r >= '0' && *r <= '9')
+    {
+      if (num < 0)
+	num = 0;
+      num = num * 10 + *r - '0';
+      r++;
+    }
+  *regex = r;
+  return num;
+}
+
+
+static reg_errcode_t
+tre_parse_bound(tre_parse_ctx_t *ctx, tre_ast_node_t **result)
+{
+  int min, max;
+  const tre_char_t *r = ctx->re;
+  const tre_char_t *start;
+  int counts_set = 0;
+
+  /* Parse number (minimum repetition count). */
+  min = -1;
+  if (r < ctx->re_end && *r >= '0' && *r <= '9') {
+    DPRINT(("tre_parse:	  min count: '%.*" STRF "'\n", ctx->re_end - r, r));
+    min = tre_parse_int(&r, ctx->re_end);
+  }
+
+  /* Parse comma and second number (maximum repetition count). */
+  max = min;
+  if (r < ctx->re_end && *r == ',')
+    {
+      r++;
+      DPRINT(("tre_parse:   max count: '%.*" STRF "'\n", ctx->re_end - r, r));
+      max = tre_parse_int(&r, ctx->re_end);
+    }
+
+  /* Check that the repeat counts are sane. */
+  if ((max >= 0 && min > max) || max > RE_DUP_MAX)
+    return REG_BADBR;
+
+
+  /*
+   '{'
+     optionally followed immediately by a number == minimum repcount
+     optionally followed by , then a number == maximum repcount
+  */
+
+
+  do {
+    int done;
+    start = r;
+
+    /* Parse count limit settings */
+    done = 0;
+    if (!counts_set)
+      while (r + 1 < ctx->re_end && !done)
+	{
+	  switch (*r)
+	    {
+	    case ',':
+	      r++;
+	      break;
+	    case ' ':
+	      r++;
+	      break;
+	    case '}':
+	      done = 1;
+	      break;
+	    default:
+	      done = 1;
+	      break;
+	    }
+	}
+  } while (start != r);
+
+  /* Missing }. */
+  if (r >= ctx->re_end)
+    return REG_EBRACE;
+
+  /* Empty contents of {}. */
+  if (r == ctx->re)
+    return REG_BADBR;
+
+  /* Parse the ending '}' or '\}'.*/
+  if (ctx->cflags & REG_EXTENDED)
+    {
+      if (r >= ctx->re_end || *r != '}')
+	return REG_BADBR;
+      r++;
+    }
+  else
+    {
+      if (r + 1 >= ctx->re_end
+	  || *r != '\\'
+	  || *(r + 1) != '}')
+	return REG_BADBR;
+      r += 2;
+    }
+
+
+  /* Create the AST node(s). */
+  if (min == 0 && max == 0)
+    {
+      *result = tre_ast_new_literal(ctx->mem, EMPTY, -1, -1);
+      if (*result == NULL)
+	return REG_ESPACE;
+    }
+  else
+    {
+      if (min < 0 && max < 0)
+	/* Only approximate parameters set, no repetitions. */
+	min = max = 1;
+
+      *result = tre_ast_new_iter(ctx->mem, *result, min, max);
+      if (!*result)
+	return REG_ESPACE;
+    }
+
+  ctx->re = r;
+  return REG_OK;
+}
+
+typedef enum {
+  PARSE_RE = 0,
+  PARSE_ATOM,
+  PARSE_MARK_FOR_SUBMATCH,
+  PARSE_BRANCH,
+  PARSE_PIECE,
+  PARSE_CATENATION,
+  PARSE_POST_CATENATION,
+  PARSE_UNION,
+  PARSE_POST_UNION,
+  PARSE_POSTFIX,
+  PARSE_RESTORE_CFLAGS
+} tre_parse_re_stack_symbol_t;
+
+
+static reg_errcode_t
+tre_parse(tre_parse_ctx_t *ctx)
+{
+  tre_ast_node_t *result = NULL;
+  tre_parse_re_stack_symbol_t symbol;
+  reg_errcode_t status = REG_OK;
+  tre_stack_t *stack = ctx->stack;
+  int bottom = tre_stack_num_objects(stack);
+  int depth = 0;
+
+  DPRINT(("tre_parse: parsing '%.*" STRF "', len = %d\n",
+	  ctx->len, ctx->re, ctx->len));
+
+  if (!ctx->nofirstsub)
+    {
+      STACK_PUSH(stack, ctx->re);
+      STACK_PUSH(stack, ctx->submatch_id);
+      STACK_PUSH(stack, PARSE_MARK_FOR_SUBMATCH);
+      ctx->submatch_id++;
+    }
+  STACK_PUSH(stack, PARSE_RE);
+  ctx->re_start = ctx->re;
+  ctx->re_end = ctx->re + ctx->len;
+
+
+  /* The following is basically just a recursive descent parser.  I use
+     an explicit stack instead of recursive functions mostly because of
+     two reasons: compatibility with systems which have an overflowable
+     call stack, and efficiency (both in lines of code and speed).  */
+  while (tre_stack_num_objects(stack) > bottom && status == REG_OK)
+    {
+      if (status != REG_OK)
+	break;
+      symbol = (tre_parse_re_stack_symbol_t)tre_stack_pop(stack);
+      switch (symbol)
+	{
+	case PARSE_RE:
+	  /* Parse a full regexp.  A regexp is one or more branches,
+	     separated by the union operator `|'. */
+	  if (ctx->cflags & REG_EXTENDED)
+	    STACK_PUSHX(stack, PARSE_UNION);
+	  STACK_PUSHX(stack, PARSE_BRANCH);
+	  break;
+
+	case PARSE_BRANCH:
+	  /* Parse a branch.  A branch is one or more pieces, concatenated.
+	     A piece is an atom possibly followed by a postfix operator. */
+	  STACK_PUSHX(stack, PARSE_CATENATION);
+	  STACK_PUSHX(stack, PARSE_PIECE);
+	  break;
+
+	case PARSE_PIECE:
+	  /* Parse a piece.  A piece is an atom possibly followed by one
+	     or more postfix operators. */
+	  STACK_PUSHX(stack, PARSE_POSTFIX);
+	  STACK_PUSHX(stack, PARSE_ATOM);
+	  break;
+
+	case PARSE_CATENATION:
+	  /* If the expression has not ended, parse another piece. */
+	  {
+	    tre_char_t c;
+	    if (ctx->re >= ctx->re_end)
+	      break;
+	    c = *ctx->re;
+	    if (ctx->cflags & REG_EXTENDED && c == '|')
+	      break;
+	    if ((ctx->cflags & REG_EXTENDED
+	         && c == ')' && depth > 0)
+	        || (!(ctx->cflags & REG_EXTENDED)
+		    && (c == '\\'
+		        && *(ctx->re + 1) == ')')))
+	      {
+	        if (!(ctx->cflags & REG_EXTENDED) && depth == 0)
+	          status = REG_EPAREN;
+	        DPRINT(("tre_parse:	  group end: '%.*" STRF "'\n",
+		        ctx->re_end - ctx->re, ctx->re));
+	        depth--;
+	        if (!(ctx->cflags & REG_EXTENDED))
+	          ctx->re += 2;
+	        break;
+	      }
+
+	    /* Left associative concatenation. */
+	    STACK_PUSHX(stack, PARSE_CATENATION);
+	    STACK_PUSHX(stack, result);
+	    STACK_PUSHX(stack, PARSE_POST_CATENATION);
+	    STACK_PUSHX(stack, PARSE_PIECE);
+	    break;
+	  }
+
+	case PARSE_POST_CATENATION:
+	  {
+	    tre_ast_node_t *tree = tre_stack_pop(stack);
+	    tre_ast_node_t *tmp_node;
+	    tmp_node = tre_ast_new_catenation(ctx->mem, tree, result);
+	    if (!tmp_node)
+	      return REG_ESPACE;
+	    result = tmp_node;
+	    break;
+	  }
+
+	case PARSE_UNION:
+	  if (ctx->re >= ctx->re_end)
+	    break;
+	  switch (*ctx->re)
+	    {
+	    case '|':
+	      DPRINT(("tre_parse:	union: '%.*" STRF "'\n",
+		      ctx->re_end - ctx->re, ctx->re));
+	      STACK_PUSHX(stack, PARSE_UNION);
+	      STACK_PUSHX(stack, result);
+	      STACK_PUSHX(stack, PARSE_POST_UNION);
+	      STACK_PUSHX(stack, PARSE_BRANCH);
+	      ctx->re++;
+	      break;
+
+	    case ')':
+	      ctx->re++;
+	      break;
+
+	    default:
+	      break;
+	    }
+	  break;
+
+	case PARSE_POST_UNION:
+	  {
+	    tre_ast_node_t *tmp_node;
+	    tre_ast_node_t *tree = tre_stack_pop(stack);
+	    tmp_node = tre_ast_new_union(ctx->mem, tree, result);
+	    if (!tmp_node)
+	      return REG_ESPACE;
+	    result = tmp_node;
+	    break;
+	  }
+
+	case PARSE_POSTFIX:
+	  /* Parse postfix operators. */
+	  if (ctx->re >= ctx->re_end)
+	    break;
+	  switch (*ctx->re)
+	    {
+	    case '+':
+	    case '?':
+	      if (!(ctx->cflags & REG_EXTENDED))
+	        break;
+	    case '*':
+	      {
+		tre_ast_node_t *tmp_node;
+		int rep_min = 0;
+		int rep_max = -1;
+		if (*ctx->re == '+')
+		  rep_min = 1;
+		if (*ctx->re == '?')
+		  rep_max = 1;
+
+		ctx->re++;
+		tmp_node = tre_ast_new_iter(ctx->mem, result, rep_min, rep_max);
+		if (tmp_node == NULL)
+		  return REG_ESPACE;
+		result = tmp_node;
+		STACK_PUSHX(stack, PARSE_POSTFIX);
+		break;
+	      }
+
+	    case '\\':
+	      /* "\{" is special without REG_EXTENDED */
+	      if (!(ctx->cflags & REG_EXTENDED)
+		  && ctx->re + 1 < ctx->re_end
+		  && *(ctx->re + 1) == '{')
+		{
+		  ctx->re++;
+		  goto parse_brace;
+		}
+	      else
+		break;
+
+	    case '{':
+	      /* "{" is literal without REG_EXTENDED */
+	      if (!(ctx->cflags & REG_EXTENDED))
+		break;
+
+	    parse_brace:
+	      DPRINT(("tre_parse:	bound: '%.*" STRF "'\n",
+		      ctx->re_end - ctx->re, ctx->re));
+	      ctx->re++;
+
+	      status = tre_parse_bound(ctx, &result);
+	      if (status != REG_OK)
+		return status;
+	      STACK_PUSHX(stack, PARSE_POSTFIX);
+	      break;
+	    }
+	  break;
+
+	case PARSE_ATOM:
+	  /* Parse an atom.  An atom is a regular expression enclosed in `()',
+	     an empty set of `()', a bracket expression, `.', `^', `$',
+	     a `\' followed by a character, or a single character. */
+
+	  /* End of regexp? (empty string). */
+	  if (ctx->re >= ctx->re_end)
+	    goto parse_literal;
+
+	  switch (*ctx->re)
+	    {
+	    case '(':  /* parenthesized subexpression */
+
+	      if (ctx->cflags & REG_EXTENDED
+		  || (ctx->re > ctx->re_start
+		      && *(ctx->re - 1) == '\\'))
+		{
+		  depth++;
+		    {
+		      DPRINT(("tre_parse: group begin: '%.*" STRF
+			      "', submatch %d\n",
+			      ctx->re_end - ctx->re, ctx->re,
+			      ctx->submatch_id));
+		      ctx->re++;
+		      /* First parse a whole RE, then mark the resulting tree
+			 for submatching. */
+		      STACK_PUSHX(stack, ctx->submatch_id);
+		      STACK_PUSHX(stack, PARSE_MARK_FOR_SUBMATCH);
+		      STACK_PUSHX(stack, PARSE_RE);
+		      ctx->submatch_id++;
+		    }
+		}
+	      else
+		goto parse_literal;
+	      break;
+
+	    case ')':  /* end of current subexpression */
+	      if ((ctx->cflags & REG_EXTENDED && depth > 0)
+		  || (ctx->re > ctx->re_start
+		      && *(ctx->re - 1) == '\\'))
+		{
+		  DPRINT(("tre_parse:	    empty: '%.*" STRF "'\n",
+			  ctx->re_end - ctx->re, ctx->re));
+		  /* We were expecting an atom, but instead the current
+		     subexpression was closed.	POSIX leaves the meaning of
+		     this to be implementation-defined.	 We interpret this as
+		     an empty expression (which matches an empty string).  */
+		  result = tre_ast_new_literal(ctx->mem, EMPTY, -1, -1);
+		  if (result == NULL)
+		    return REG_ESPACE;
+		  if (!(ctx->cflags & REG_EXTENDED))
+		    ctx->re--;
+		}
+	      else
+		goto parse_literal;
+	      break;
+
+	    case '[': /* bracket expression */
+	      DPRINT(("tre_parse:     bracket: '%.*" STRF "'\n",
+		      ctx->re_end - ctx->re, ctx->re));
+	      ctx->re++;
+	      status = tre_parse_bracket(ctx, &result);
+	      if (status != REG_OK)
+		return status;
+	      break;
+
+	    case '\\':
+	      /* If this is "\(" or "\)" chew off the backslash and
+		 try again. */
+	      if (!(ctx->cflags & REG_EXTENDED)
+		  && ctx->re + 1 < ctx->re_end
+		  && (*(ctx->re + 1) == '('
+		      || *(ctx->re + 1) == ')'))
+		{
+		  ctx->re++;
+		  STACK_PUSHX(stack, PARSE_ATOM);
+		  break;
+		}
+
+	      if (ctx->re + 1 >= ctx->re_end)
+		/* Trailing backslash. */
+		return REG_EESCAPE;
+
+	      DPRINT(("tre_parse:  bleep: '%.*" STRF "'\n",
+		      ctx->re_end - ctx->re, ctx->re));
+	      ctx->re++;
+	      switch (*ctx->re)
+		{
+		default:
+		  if (!(ctx->cflags & REG_EXTENDED) && tre_isdigit(*ctx->re))
+		    {
+		      /* Back reference. */
+		      int val = *ctx->re - '0';
+		      DPRINT(("tre_parse:     backref: '%.*" STRF "'\n",
+			      ctx->re_end - ctx->re + 1, ctx->re - 1));
+		      result = tre_ast_new_literal(ctx->mem, BACKREF, val,
+						   ctx->position);
+		      if (result == NULL)
+			return REG_ESPACE;
+		      ctx->position++;
+		      ctx->max_backref = MAX(val, ctx->max_backref);
+		      ctx->re++;
+		    }
+		  else
+		    {
+		      /* Escaped character. */
+		      DPRINT(("tre_parse:     escaped: '%.*" STRF "'\n",
+			      ctx->re_end - ctx->re + 1, ctx->re - 1));
+		      result = tre_ast_new_literal(ctx->mem, *ctx->re, *ctx->re,
+						   ctx->position);
+		      ctx->position++;
+		      ctx->re++;
+		    }
+		  break;
+		}
+	      if (result == NULL)
+		return REG_ESPACE;
+	      break;
+
+	    case '.':	 /* the any-symbol */
+	      DPRINT(("tre_parse:	  any: '%.*" STRF "'\n",
+		      ctx->re_end - ctx->re, ctx->re));
+	      if (ctx->cflags & REG_NEWLINE)
+		{
+		  tre_ast_node_t *tmp1;
+		  tre_ast_node_t *tmp2;
+		  tmp1 = tre_ast_new_literal(ctx->mem, 0, '\n' - 1,
+					     ctx->position);
+		  if (!tmp1)
+		    return REG_ESPACE;
+		  tmp2 = tre_ast_new_literal(ctx->mem, '\n' + 1, TRE_CHAR_MAX,
+					     ctx->position + 1);
+		  if (!tmp2)
+		    return REG_ESPACE;
+		  result = tre_ast_new_union(ctx->mem, tmp1, tmp2);
+		  if (!result)
+		    return REG_ESPACE;
+		  ctx->position += 2;
+		}
+	      else
+		{
+		  result = tre_ast_new_literal(ctx->mem, 0, TRE_CHAR_MAX,
+					       ctx->position);
+		  if (!result)
+		    return REG_ESPACE;
+		  ctx->position++;
+		}
+	      ctx->re++;
+	      break;
+
+	    case '^':	 /* beginning of line assertion */
+	      /* '^' has a special meaning everywhere in EREs, and in the
+		 beginning of the RE and after \( is BREs. */
+	      if (ctx->cflags & REG_EXTENDED
+		  || (ctx->re - 2 >= ctx->re_start
+		      && *(ctx->re - 2) == '\\'
+		      && *(ctx->re - 1) == '(')
+		  || ctx->re == ctx->re_start)
+		{
+		  DPRINT(("tre_parse:	      BOL: '%.*" STRF "'\n",
+			  ctx->re_end - ctx->re, ctx->re));
+		  result = tre_ast_new_literal(ctx->mem, ASSERTION,
+					       ASSERT_AT_BOL, -1);
+		  if (result == NULL)
+		    return REG_ESPACE;
+		  ctx->re++;
+		}
+	      else
+		goto parse_literal;
+	      break;
+
+	    case '$':	 /* end of line assertion. */
+	      /* '$' is special everywhere in EREs, and in the end of the
+		 string and before \) is BREs. */
+	      if (ctx->cflags & REG_EXTENDED
+		  || (ctx->re + 2 < ctx->re_end
+		      && *(ctx->re + 1) == '\\'
+		      && *(ctx->re + 2) == ')')
+		  || ctx->re + 1 == ctx->re_end)
+		{
+		  DPRINT(("tre_parse:	      EOL: '%.*" STRF "'\n",
+			  ctx->re_end - ctx->re, ctx->re));
+		  result = tre_ast_new_literal(ctx->mem, ASSERTION,
+					       ASSERT_AT_EOL, -1);
+		  if (result == NULL)
+		    return REG_ESPACE;
+		  ctx->re++;
+		}
+	      else
+		goto parse_literal;
+	      break;
+
+	    default:
+	    parse_literal:
+
+	      /* We are expecting an atom.  If the subexpression (or the whole
+		 regexp ends here, we interpret it as an empty expression
+		 (which matches an empty string).  */
+	      if (
+		  (ctx->re >= ctx->re_end
+		   || *ctx->re == '*'
+		   || (ctx->cflags & REG_EXTENDED
+		       && (*ctx->re == '|'
+			   || *ctx->re == '{'
+			   || *ctx->re == '+'
+			   || *ctx->re == '?'))
+		   /* Test for "\)" in BRE mode. */
+		   || (!(ctx->cflags & REG_EXTENDED)
+		       && ctx->re + 1 < ctx->re_end
+		       && *ctx->re == '\\'
+		       && *(ctx->re + 1) == '{')))
+		{
+		  DPRINT(("tre_parse:	    empty: '%.*" STRF "'\n",
+			  ctx->re_end - ctx->re, ctx->re));
+		  result = tre_ast_new_literal(ctx->mem, EMPTY, -1, -1);
+		  if (!result)
+		    return REG_ESPACE;
+		  break;
+		}
+
+	      DPRINT(("tre_parse:     literal: '%.*" STRF "'\n",
+		      ctx->re_end - ctx->re, ctx->re));
+	      /* Note that we can't use an tre_isalpha() test here, since there
+		 may be characters which are alphabetic but neither upper or
+		 lower case. */
+	      if (ctx->cflags & REG_ICASE
+		  && (tre_isupper(*ctx->re) || tre_islower(*ctx->re)))
+		{
+		  tre_ast_node_t *tmp1;
+		  tre_ast_node_t *tmp2;
+
+		  /* XXX - Can there be more than one opposite-case
+		     counterpoints for some character in some locale?  Or
+		     more than two characters which all should be regarded
+		     the same character if case is ignored?  If yes, there
+		     does not seem to be a portable way to detect it.  I guess
+		     that at least for multi-character collating elements there
+		     could be several opposite-case counterpoints, but they
+		     cannot be supported portably anyway. */
+		  tmp1 = tre_ast_new_literal(ctx->mem, tre_toupper(*ctx->re),
+					     tre_toupper(*ctx->re),
+					     ctx->position);
+		  if (!tmp1)
+		    return REG_ESPACE;
+		  tmp2 = tre_ast_new_literal(ctx->mem, tre_tolower(*ctx->re),
+					     tre_tolower(*ctx->re),
+					     ctx->position);
+		  if (!tmp2)
+		    return REG_ESPACE;
+		  result = tre_ast_new_union(ctx->mem, tmp1, tmp2);
+		  if (!result)
+		    return REG_ESPACE;
+		}
+	      else
+		{
+		  result = tre_ast_new_literal(ctx->mem, *ctx->re, *ctx->re,
+					       ctx->position);
+		  if (!result)
+		    return REG_ESPACE;
+		}
+	      ctx->position++;
+	      ctx->re++;
+	      break;
+	    }
+	  break;
+
+	case PARSE_MARK_FOR_SUBMATCH:
+	  {
+	    int submatch_id = (int)tre_stack_pop(stack);
+
+	    if (result->submatch_id >= 0)
+	      {
+		tre_ast_node_t *n, *tmp_node;
+		n = tre_ast_new_literal(ctx->mem, EMPTY, -1, -1);
+		if (n == NULL)
+		  return REG_ESPACE;
+		tmp_node = tre_ast_new_catenation(ctx->mem, n, result);
+		if (tmp_node == NULL)
+		  return REG_ESPACE;
+		tmp_node->num_submatches = result->num_submatches;
+		result = tmp_node;
+	      }
+	    result->submatch_id = submatch_id;
+	    result->num_submatches++;
+	    break;
+	  }
+
+	case PARSE_RESTORE_CFLAGS:
+	  ctx->cflags = (int)tre_stack_pop(stack);
+	  break;
+	}
+    }
+
+  /* Check for missing closing parentheses. */
+  if (depth > 0)
+    return REG_EPAREN;
+
+  if (status == REG_OK)
+    ctx->result = result;
+
+  return status;
+}
+
+
+/***********************************************************************
+ from tre-compile.c
+***********************************************************************/
+
+/*
+  Algorithms to setup tags so that submatch addressing can be done.
+*/
+
+
+/* Inserts a catenation node to the root of the tree given in `node'.
+   As the left child a new tag with number `tag_id' to `node' is added,
+   and the right child is the old root. */
+/*              OR                  */
+/* Inserts a catenation node to the root of the tree given in `node'.
+   As the right child a new tag with number `tag_id' to `node' is added,
+   and the left child is the old root. */
+static reg_errcode_t
+tre_add_tag(tre_mem_t mem, tre_ast_node_t *node, int tag_id, int right)
+{
+  tre_catenation_t *c;
+  tre_ast_node_t *child_tag, *child_old;
+
+  DPRINT(("add_tag_%s: tag %d\n", right ? "right" : "left", tag_id));
+
+  c = tre_mem_alloc(mem, sizeof(*c));
+  if (c == NULL)
+    return REG_ESPACE;
+  child_tag = tre_ast_new_literal(mem, TAG, tag_id, -1);
+  if (child_tag == NULL)
+    return REG_ESPACE;
+  child_old = tre_mem_alloc(mem, sizeof(tre_ast_node_t));
+  if (child_old == NULL)
+    return REG_ESPACE;
+
+  child_old->obj = node->obj;
+  child_old->type = node->type;
+  child_old->nullable = -1;
+  child_old->submatch_id = -1;
+  child_old->firstpos = NULL;
+  child_old->lastpos = NULL;
+  child_old->num_tags = 0;
+  node->obj = c;
+  node->type = CATENATION;
+
+  c->right = c->left = child_old;
+  if (right) c->right = child_tag;
+  else c->left = child_tag;
+
+  return REG_OK;
+}
+
+typedef enum {
+  ADDTAGS_RECURSE,
+  ADDTAGS_AFTER_ITERATION,
+  ADDTAGS_AFTER_UNION_LEFT,
+  ADDTAGS_AFTER_UNION_RIGHT,
+  ADDTAGS_AFTER_CAT_LEFT,
+  ADDTAGS_AFTER_CAT_RIGHT,
+  ADDTAGS_SET_SUBMATCH_END
+} tre_addtags_symbol_t;
+
+
+typedef struct {
+  int tag;
+  int next_tag;
+} tre_tag_states_t;
+
+/* Adds tags to appropriate locations in the parse tree in `tree', so that
+   subexpressions marked for submatch addressing can be traced. */
+static reg_errcode_t
+tre_add_tags(tre_mem_t mem, tre_stack_t *stack, tre_ast_node_t *tree,
+	     tre_tnfa_t *tnfa)
+{
+  reg_errcode_t status = REG_OK;
+  tre_addtags_symbol_t symbol;
+  tre_ast_node_t *node = tree; /* Tree node we are currently looking at. */
+  int bottom = tre_stack_num_objects(stack);
+  /* True for first pass (counting number of needed tags) */
+  int first_pass = (mem == NULL || tnfa == NULL);
+  int *regset, *orig_regset;
+  int num_tags = 0; /* Total number of tags. */
+  int tag = 0;	    /* The tag that is to be added next. */
+  int next_tag = 1; /* Next tag to use after this one. */
+  int *parents;	    /* Stack of submatches the current submatch is
+		       contained in. */
+  tre_tag_states_t *saved_states;
+
+  tre_tag_direction_t direction = TRE_TAG_MINIMIZE;
+  if (!first_pass)
+      tnfa->end_tag = 0;
+
+  regset = xmalloc(sizeof(*regset) * ((tnfa->num_submatches + 1) * 2));
+  if (regset == NULL)
+    return REG_ESPACE;
+  regset[0] = -1;
+  orig_regset = regset;
+
+  parents = xmalloc(sizeof(*parents) * (tnfa->num_submatches + 1));
+  if (parents == NULL)
+    {
+      xfree(regset);
+      return REG_ESPACE;
+    }
+  parents[0] = -1;
+
+  saved_states = xmalloc(sizeof(*saved_states) * (tnfa->num_submatches + 1));
+  if (saved_states == NULL)
+    {
+      xfree(regset);
+      xfree(parents);
+      return REG_ESPACE;
+    }
+  else
+    {
+      unsigned int i;
+      for (i = 0; i <= tnfa->num_submatches; i++)
+	saved_states[i].tag = -1;
+    }
+
+  STACK_PUSH(stack, node);
+  STACK_PUSH(stack, ADDTAGS_RECURSE);
+
+  while (tre_stack_num_objects(stack) > bottom)
+    {
+      if (status != REG_OK)
+	break;
+
+      symbol = (tre_addtags_symbol_t)tre_stack_pop(stack);
+      switch (symbol)
+	{
+
+	case ADDTAGS_SET_SUBMATCH_END:
+	  {
+	    int id = (int)tre_stack_pop(stack);
+	    int i;
+
+	    /* Add end of this submatch to regset. */
+	    for (i = 0; regset[i] >= 0; i++);
+	    regset[i] = id * 2 + 1;
+	    regset[i + 1] = -1;
+
+	    /* Pop this submatch from the parents stack. */
+	    for (i = 0; parents[i] >= 0; i++);
+	    parents[i - 1] = -1;
+	    break;
+	  }
+
+	case ADDTAGS_RECURSE:
+	  node = tre_stack_pop(stack);
+
+	  if (node->submatch_id >= 0)
+	    {
+	      int id = node->submatch_id;
+	      int i;
+
+
+	      /* Add start of this submatch to regset. */
+	      for (i = 0; regset[i] >= 0; i++);
+	      regset[i] = id * 2;
+	      regset[i + 1] = -1;
+
+	      if (!first_pass)
+		{
+		  for (i = 0; parents[i] >= 0; i++);
+		  tnfa->submatch_data[id].parents = NULL;
+		  if (i > 0)
+		    {
+		      int *p = xmalloc(sizeof(*p) * (i + 1));
+		      if (p == NULL)
+			{
+			  status = REG_ESPACE;
+			  break;
+			}
+		      assert(tnfa->submatch_data[id].parents == NULL);
+		      tnfa->submatch_data[id].parents = p;
+		      for (i = 0; parents[i] >= 0; i++)
+			p[i] = parents[i];
+		      p[i] = -1;
+		    }
+		}
+
+	      /* Add end of this submatch to regset after processing this
+		 node. */
+	      STACK_PUSHX(stack, node->submatch_id);
+	      STACK_PUSHX(stack, ADDTAGS_SET_SUBMATCH_END);
+	    }
+
+	  switch (node->type)
+	    {
+	    case LITERAL:
+	      {
+		tre_literal_t *lit = node->obj;
+
+		if (!IS_SPECIAL(lit) || IS_BACKREF(lit))
+		  {
+		    int i;
+		    DPRINT(("Literal %d-%d\n",
+			    (int)lit->code_min, (int)lit->code_max));
+		    if (regset[0] >= 0)
+		      {
+			/* Regset is not empty, so add a tag before the
+			   literal or backref. */
+			if (!first_pass)
+			  {
+			    status = tre_add_tag(mem, node, tag, 0 /*left*/);
+			    tnfa->tag_directions[tag] = direction;
+			    /* Go through the regset and set submatch data for
+			       submatches that are using this tag. */
+			    for (i = 0; regset[i] >= 0; i++)
+			      {
+				int id = regset[i] >> 1;
+				int start = !(regset[i] & 1);
+				DPRINT(("  Using tag %d for %s offset of "
+					"submatch %d\n", tag,
+					start ? "start" : "end", id));
+				if (start)
+				  tnfa->submatch_data[id].so_tag = tag;
+				else
+				  tnfa->submatch_data[id].eo_tag = tag;
+			      }
+			  }
+			else
+			  {
+			    DPRINT(("  num_tags = 1\n"));
+			    node->num_tags = 1;
+			  }
+
+			DPRINT(("  num_tags++\n"));
+			regset[0] = -1;
+			tag = next_tag;
+			num_tags++;
+			next_tag++;
+		      }
+		  }
+		else
+		  {
+		    assert(!IS_TAG(lit));
+		  }
+		break;
+	      }
+	    case CATENATION:
+	      {
+		tre_catenation_t *cat = node->obj;
+		tre_ast_node_t *left = cat->left;
+		tre_ast_node_t *right = cat->right;
+		int reserved_tag = -1;
+		DPRINT(("Catenation, next_tag = %d\n", next_tag));
+
+
+		/* After processing right child. */
+		STACK_PUSHX(stack, node);
+		STACK_PUSHX(stack, ADDTAGS_AFTER_CAT_RIGHT);
+
+		/* Process right child. */
+		STACK_PUSHX(stack, right);
+		STACK_PUSHX(stack, ADDTAGS_RECURSE);
+
+		/* After processing left child. */
+		STACK_PUSHX(stack, next_tag + left->num_tags);
+		DPRINT(("  Pushing %d for after left\n",
+			next_tag + left->num_tags));
+		if (left->num_tags > 0 && right->num_tags > 0)
+		  {
+		    /* Reserve the next tag to the right child. */
+		    DPRINT(("  Reserving next_tag %d to right child\n",
+			    next_tag));
+		    reserved_tag = next_tag;
+		    next_tag++;
+		  }
+		STACK_PUSHX(stack, reserved_tag);
+		STACK_PUSHX(stack, ADDTAGS_AFTER_CAT_LEFT);
+
+		/* Process left child. */
+		STACK_PUSHX(stack, left);
+		STACK_PUSHX(stack, ADDTAGS_RECURSE);
+
+		}
+	      break;
+	    case ITERATION:
+	      {
+		tre_iteration_t *iter = node->obj;
+		DPRINT(("Iteration\n"));
+
+		if (first_pass)
+		  {
+		    STACK_PUSHX(stack, regset[0] >= 0);
+		  }
+		else
+		  {
+		    STACK_PUSHX(stack, tag);
+		  }
+		STACK_PUSHX(stack, node);
+		STACK_PUSHX(stack, ADDTAGS_AFTER_ITERATION);
+
+		STACK_PUSHX(stack, iter->arg);
+		STACK_PUSHX(stack, ADDTAGS_RECURSE);
+
+		/* Regset is not empty, so add a tag here. */
+		if (regset[0] >= 0)
+		  {
+		    if (!first_pass)
+		      {
+			int i;
+			status = tre_add_tag(mem, node, tag, 0 /*left*/);
+			tnfa->tag_directions[tag] = direction;
+			/* Go through the regset and set submatch data for
+			   submatches that are using this tag. */
+			for (i = 0; regset[i] >= 0; i++)
+			  {
+			    int id = regset[i] >> 1;
+			    int start = !(regset[i] & 1);
+			    DPRINT(("  Using tag %d for %s offset of "
+				    "submatch %d\n", tag,
+				    start ? "start" : "end", id));
+			    if (start)
+			      tnfa->submatch_data[id].so_tag = tag;
+			    else
+			      tnfa->submatch_data[id].eo_tag = tag;
+			  }
+		      }
+
+		    DPRINT(("  num_tags++\n"));
+		    regset[0] = -1;
+		    tag = next_tag;
+		    num_tags++;
+		    next_tag++;
+		  }
+		direction = TRE_TAG_MINIMIZE;
+	      }
+	      break;
+	    case UNION:
+	      {
+		tre_union_t *uni = node->obj;
+		tre_ast_node_t *left = uni->left;
+		tre_ast_node_t *right = uni->right;
+		int left_tag;
+		int right_tag;
+
+		if (regset[0] >= 0)
+		  {
+		    left_tag = next_tag;
+		    right_tag = next_tag + 1;
+		  }
+		else
+		  {
+		    left_tag = tag;
+		    right_tag = next_tag;
+		  }
+
+		DPRINT(("Union\n"));
+
+		/* After processing right child. */
+		STACK_PUSHX(stack, right_tag);
+		STACK_PUSHX(stack, left_tag);
+		STACK_PUSHX(stack, regset);
+		STACK_PUSHX(stack, regset[0] >= 0);
+		STACK_PUSHX(stack, node);
+		STACK_PUSHX(stack, right);
+		STACK_PUSHX(stack, left);
+		STACK_PUSHX(stack, ADDTAGS_AFTER_UNION_RIGHT);
+
+		/* Process right child. */
+		STACK_PUSHX(stack, right);
+		STACK_PUSHX(stack, ADDTAGS_RECURSE);
+
+		/* After processing left child. */
+		STACK_PUSHX(stack, ADDTAGS_AFTER_UNION_LEFT);
+
+		/* Process left child. */
+		STACK_PUSHX(stack, left);
+		STACK_PUSHX(stack, ADDTAGS_RECURSE);
+
+		/* Regset is not empty, so add a tag here. */
+		if (regset[0] >= 0)
+		  {
+		    if (!first_pass)
+		      {
+			int i;
+			status = tre_add_tag(mem, node, tag, 0 /*left*/);
+			tnfa->tag_directions[tag] = direction;
+			/* Go through the regset and set submatch data for
+			   submatches that are using this tag. */
+			for (i = 0; regset[i] >= 0; i++)
+			  {
+			    int id = regset[i] >> 1;
+			    int start = !(regset[i] & 1);
+			    DPRINT(("  Using tag %d for %s offset of "
+				    "submatch %d\n", tag,
+				    start ? "start" : "end", id));
+			    if (start)
+			      tnfa->submatch_data[id].so_tag = tag;
+			    else
+			      tnfa->submatch_data[id].eo_tag = tag;
+			  }
+		      }
+
+		    DPRINT(("  num_tags++\n"));
+		    regset[0] = -1;
+		    tag = next_tag;
+		    num_tags++;
+		    next_tag++;
+		  }
+
+		if (node->num_submatches > 0)
+		  {
+		    /* The next two tags are reserved for markers. */
+		    next_tag++;
+		    tag = next_tag;
+		    next_tag++;
+		  }
+
+		break;
+	      }
+	    }
+
+	  if (node->submatch_id >= 0)
+	    {
+	      int i;
+	      /* Push this submatch on the parents stack. */
+	      for (i = 0; parents[i] >= 0; i++);
+	      parents[i] = node->submatch_id;
+	      parents[i + 1] = -1;
+	    }
+
+	  break; /* end case: ADDTAGS_RECURSE */
+
+	case ADDTAGS_AFTER_ITERATION:
+	  {
+	    int enter_tag;
+	    node = tre_stack_pop(stack);
+	    if (first_pass)
+		node->num_tags = ((tre_iteration_t *)node->obj)->arg->num_tags
+		  + (int)tre_stack_pop(stack);
+	    else
+		enter_tag = (int)tre_stack_pop(stack);
+
+	    DPRINT(("After iteration\n"));
+	    direction = TRE_TAG_MAXIMIZE;
+	    break;
+	  }
+
+	case ADDTAGS_AFTER_CAT_LEFT:
+	  {
+	    int new_tag = (int)tre_stack_pop(stack);
+	    next_tag = (int)tre_stack_pop(stack);
+	    DPRINT(("After cat left, tag = %d, next_tag = %d\n",
+		    tag, next_tag));
+	    if (new_tag >= 0)
+	      {
+		DPRINT(("  Setting tag to %d\n", new_tag));
+		tag = new_tag;
+	      }
+	    break;
+	  }
+
+	case ADDTAGS_AFTER_CAT_RIGHT:
+	  DPRINT(("After cat right\n"));
+	  node = tre_stack_pop(stack);
+	  if (first_pass)
+	    node->num_tags = ((tre_catenation_t *)node->obj)->left->num_tags
+	      + ((tre_catenation_t *)node->obj)->right->num_tags;
+	  break;
+
+	case ADDTAGS_AFTER_UNION_LEFT:
+	  DPRINT(("After union left\n"));
+	  /* Lift the bottom of the `regset' array so that when processing
+	     the right operand the items currently in the array are
+	     invisible.	 The original bottom was saved at ADDTAGS_UNION and
+	     will be restored at ADDTAGS_AFTER_UNION_RIGHT below. */
+	  while (*regset >= 0)
+	    regset++;
+	  break;
+
+	case ADDTAGS_AFTER_UNION_RIGHT:
+	  {
+	    int added_tags, tag_left, tag_right;
+	    tre_ast_node_t *left = tre_stack_pop(stack);
+	    tre_ast_node_t *right = tre_stack_pop(stack);
+	    DPRINT(("After union right\n"));
+	    node = tre_stack_pop(stack);
+	    added_tags = (int)tre_stack_pop(stack);
+	    if (first_pass)
+	      {
+		node->num_tags = ((tre_union_t *)node->obj)->left->num_tags
+		  + ((tre_union_t *)node->obj)->right->num_tags + added_tags
+		  + ((node->num_submatches > 0) ? 2 : 0);
+	      }
+	    regset = tre_stack_pop(stack);
+	    tag_left = (int)tre_stack_pop(stack);
+	    tag_right = (int)tre_stack_pop(stack);
+
+	    /* Add tags after both children, the left child gets a smaller
+	       tag than the right child.  This guarantees that we prefer
+	       the left child over the right child. */
+	    /* XXX - This is not always necessary (if the children have
+	       tags which must be seen for every match of that child). */
+	    /* XXX - Check if this is the only place where tre_add_tag_right
+	       is used.	 If so, use tre_add_tag_left (putting the tag before
+	       the child as opposed after the child) and throw away
+	       tre_add_tag_right. */
+	    if (node->num_submatches > 0)
+	      {
+		if (!first_pass)
+		  {
+		    status = tre_add_tag(mem, left, tag_left, 1 /*right*/);
+		    tnfa->tag_directions[tag] = TRE_TAG_MAXIMIZE;
+		    status = tre_add_tag(mem, right, tag_right, 1 /*right*/);
+		    tnfa->tag_directions[tag] = TRE_TAG_MAXIMIZE;
+		  }
+		DPRINT(("  num_tags += 2\n"));
+		num_tags += 2;
+	      }
+	    direction = TRE_TAG_MAXIMIZE;
+	    break;
+	  }
+
+	default:
+	  assert(0);
+	  break;
+
+	} /* end switch(symbol) */
+    } /* end while(tre_stack_num_objects(stack) > bottom) */
+
+  if (!first_pass)
+    {
+      int i;
+      /* Go through the regset and set submatch data for
+	 submatches that are using this tag. */
+      for (i = 0; regset[i] >= 0; i++)
+	{
+	  int id = regset[i] >> 1;
+	  int start = !(regset[i] & 1);
+	  DPRINT(("  Using tag %d for %s offset of "
+		  "submatch %d\n", num_tags,
+		  start ? "start" : "end", id));
+	  if (start)
+	    tnfa->submatch_data[id].so_tag = num_tags;
+	  else
+	    tnfa->submatch_data[id].eo_tag = num_tags;
+	}
+    }
+
+  DPRINT(("tre_add_tags: %s complete.  Number of tags %d.\n",
+	  first_pass? "First pass" : "Second pass", num_tags));
+
+  assert(tree->num_tags == num_tags);
+  tnfa->end_tag = num_tags;
+  tnfa->num_tags = num_tags;
+  xfree(orig_regset);
+  xfree(parents);
+  xfree(saved_states);
+  return status;
+}
+
+
+
+/*
+  AST to TNFA compilation routines.
+*/
+
+typedef enum {
+  COPY_RECURSE,
+  COPY_SET_RESULT_PTR
+} tre_copyast_symbol_t;
+
+/* Flags for tre_copy_ast(). */
+#define COPY_REMOVE_TAGS	 1
+#define COPY_MAXIMIZE_FIRST_TAG	 2
+
+static reg_errcode_t
+tre_copy_ast(tre_mem_t mem, tre_stack_t *stack, tre_ast_node_t *ast,
+	     int flags, int *pos_add, tre_tag_direction_t *tag_directions,
+	     tre_ast_node_t **copy, int *max_pos)
+{
+  reg_errcode_t status = REG_OK;
+  int bottom = tre_stack_num_objects(stack);
+  int num_copied = 0;
+  int first_tag = 1;
+  tre_ast_node_t **result = copy;
+  tre_copyast_symbol_t symbol;
+
+  STACK_PUSH(stack, ast);
+  STACK_PUSH(stack, COPY_RECURSE);
+
+  while (status == REG_OK && tre_stack_num_objects(stack) > bottom)
+    {
+      tre_ast_node_t *node;
+      if (status != REG_OK)
+	break;
+
+      symbol = (tre_copyast_symbol_t)tre_stack_pop(stack);
+      switch (symbol)
+	{
+	case COPY_SET_RESULT_PTR:
+	  result = tre_stack_pop(stack);
+	  break;
+	case COPY_RECURSE:
+	  node = tre_stack_pop(stack);
+	  switch (node->type)
+	    {
+	    case LITERAL:
+	      {
+		tre_literal_t *lit = node->obj;
+		int pos = lit->position;
+		int min = lit->code_min;
+		int max = lit->code_max;
+		if (!IS_SPECIAL(lit) || IS_BACKREF(lit))
+		  {
+		    /* XXX - e.g. [ab] has only one position but two
+		       nodes, so we are creating holes in the state space
+		       here.  Not fatal, just wastes memory. */
+		    pos += *pos_add;
+		    num_copied++;
+		  }
+		else if (IS_TAG(lit) && (flags & COPY_REMOVE_TAGS))
+		  {
+		    /* Change this tag to empty. */
+		    min = EMPTY;
+		    max = pos = -1;
+		  }
+		else if (IS_TAG(lit) && (flags & COPY_MAXIMIZE_FIRST_TAG)
+			 && first_tag)
+		  {
+		    /* Maximize the first tag. */
+		    tag_directions[max] = TRE_TAG_MAXIMIZE;
+		    first_tag = 0;
+		  }
+		*result = tre_ast_new_literal(mem, min, max, pos);
+		if (*result == NULL)
+		  status = REG_ESPACE;
+
+		if (pos > *max_pos)
+		  *max_pos = pos;
+		break;
+	      }
+	    case UNION:
+	      {
+		tre_union_t *uni = node->obj;
+		tre_union_t *copy;
+		*result = tre_ast_new_union(mem, uni->left, uni->right);
+		if (*result == NULL)
+		  {
+		    status = REG_ESPACE;
+		    break;
+		  }
+		copy = (*result)->obj;
+		result = &copy->left;
+		STACK_PUSHX(stack, uni->right);
+		STACK_PUSHX(stack, COPY_RECURSE);
+		STACK_PUSHX(stack, &copy->right);
+		STACK_PUSHX(stack, COPY_SET_RESULT_PTR);
+		STACK_PUSHX(stack, uni->left);
+		STACK_PUSHX(stack, COPY_RECURSE);
+		break;
+	      }
+	    case CATENATION:
+	      {
+		tre_catenation_t *cat = node->obj;
+		tre_catenation_t *copy;
+		*result = tre_ast_new_catenation(mem, cat->left, cat->right);
+		if (*result == NULL)
+		  {
+		    status = REG_ESPACE;
+		    break;
+		  }
+		copy = (*result)->obj;
+		copy->left = NULL;
+		copy->right = NULL;
+		result = &copy->left;
+
+		STACK_PUSHX(stack, cat->right);
+		STACK_PUSHX(stack, COPY_RECURSE);
+		STACK_PUSHX(stack, &copy->right);
+		STACK_PUSHX(stack, COPY_SET_RESULT_PTR);
+		STACK_PUSHX(stack, cat->left);
+		STACK_PUSHX(stack, COPY_RECURSE);
+		break;
+	      }
+	    case ITERATION:
+	      {
+		tre_iteration_t *iter = node->obj;
+		STACK_PUSHX(stack, iter->arg);
+		STACK_PUSHX(stack, COPY_RECURSE);
+		*result = tre_ast_new_iter(mem, iter->arg, iter->min, iter->max);
+		if (*result == NULL)
+		  {
+		    status = REG_ESPACE;
+		    break;
+		  }
+		iter = (*result)->obj;
+		result = &iter->arg;
+		break;
+	      }
+	    default:
+	      assert(0);
+	      break;
+	    }
+	  break;
+	}
+    }
+  *pos_add += num_copied;
+  return status;
+}
+
+typedef enum {
+  EXPAND_RECURSE,
+  EXPAND_AFTER_ITER
+} tre_expand_ast_symbol_t;
+
+/* Expands each iteration node that has a finite nonzero minimum or maximum
+   iteration count to a catenated sequence of copies of the node. */
+static reg_errcode_t
+tre_expand_ast(tre_mem_t mem, tre_stack_t *stack, tre_ast_node_t *ast,
+	       int *position, tre_tag_direction_t *tag_directions,
+	       int *max_depth)
+{
+  reg_errcode_t status = REG_OK;
+  int bottom = tre_stack_num_objects(stack);
+  int pos_add = 0;
+  int pos_add_total = 0;
+  int max_pos = 0;
+  /* Approximate parameter nesting level. */
+  int iter_depth = 0;
+
+  STACK_PUSHR(stack, ast);
+  STACK_PUSHR(stack, EXPAND_RECURSE);
+  while (status == REG_OK && tre_stack_num_objects(stack) > bottom)
+    {
+      tre_ast_node_t *node;
+      tre_expand_ast_symbol_t symbol;
+
+      if (status != REG_OK)
+	break;
+
+      DPRINT(("pos_add %d\n", pos_add));
+
+      symbol = (tre_expand_ast_symbol_t)tre_stack_pop(stack);
+      node = tre_stack_pop(stack);
+      switch (symbol)
+	{
+	case EXPAND_RECURSE:
+	  switch (node->type)
+	    {
+	    case LITERAL:
+	      {
+		tre_literal_t *lit= node->obj;
+		if (!IS_SPECIAL(lit) || IS_BACKREF(lit))
+		  {
+		    lit->position += pos_add;
+		    if (lit->position > max_pos)
+		      max_pos = lit->position;
+		  }
+		break;
+	      }
+	    case UNION:
+	      {
+		tre_union_t *uni = node->obj;
+		STACK_PUSHX(stack, uni->right);
+		STACK_PUSHX(stack, EXPAND_RECURSE);
+		STACK_PUSHX(stack, uni->left);
+		STACK_PUSHX(stack, EXPAND_RECURSE);
+		break;
+	      }
+	    case CATENATION:
+	      {
+		tre_catenation_t *cat = node->obj;
+		STACK_PUSHX(stack, cat->right);
+		STACK_PUSHX(stack, EXPAND_RECURSE);
+		STACK_PUSHX(stack, cat->left);
+		STACK_PUSHX(stack, EXPAND_RECURSE);
+		break;
+	      }
+	    case ITERATION:
+	      {
+		tre_iteration_t *iter = node->obj;
+		STACK_PUSHX(stack, pos_add);
+		STACK_PUSHX(stack, node);
+		STACK_PUSHX(stack, EXPAND_AFTER_ITER);
+		STACK_PUSHX(stack, iter->arg);
+		STACK_PUSHX(stack, EXPAND_RECURSE);
+		/* If we are going to expand this node at EXPAND_AFTER_ITER
+		   then don't increase the `pos' fields of the nodes now, it
+		   will get done when expanding. */
+		if (iter->min > 1 || iter->max > 1)
+		  pos_add = 0;
+		iter_depth++;
+		DPRINT(("iter\n"));
+		break;
+	      }
+	    default:
+	      assert(0);
+	      break;
+	    }
+	  break;
+	case EXPAND_AFTER_ITER:
+	  {
+	    tre_iteration_t *iter = node->obj;
+	    int pos_add_last;
+	    pos_add = (int)tre_stack_pop(stack);
+	    pos_add_last = pos_add;
+	    if (iter->min > 1 || iter->max > 1)
+	      {
+		tre_ast_node_t *seq1 = NULL, *seq2 = NULL;
+		int i;
+		int pos_add_save = pos_add;
+
+		/* Create a catenated sequence of copies of the node. */
+		for (i = 0; i < iter->min; i++)
+		  {
+		    tre_ast_node_t *copy;
+		    /* Remove tags from all but the last copy. */
+		    int flags = ((i + 1 < iter->min)
+				 ? COPY_REMOVE_TAGS
+				 : COPY_MAXIMIZE_FIRST_TAG);
+		    DPRINT(("  pos_add %d\n", pos_add));
+		    pos_add_save = pos_add;
+		    status = tre_copy_ast(mem, stack, iter->arg, flags,
+					  &pos_add, tag_directions, &copy,
+					  &max_pos);
+		    if (status != REG_OK)
+		      return status;
+		    if (seq1 != NULL)
+		      seq1 = tre_ast_new_catenation(mem, seq1, copy);
+		    else
+		      seq1 = copy;
+		    if (seq1 == NULL)
+		      return REG_ESPACE;
+		  }
+
+		if (iter->max == -1)
+		  {
+		    /* No upper limit. */
+		    pos_add_save = pos_add;
+		    status = tre_copy_ast(mem, stack, iter->arg, 0,
+					  &pos_add, NULL, &seq2, &max_pos);
+		    if (status != REG_OK)
+		      return status;
+		    seq2 = tre_ast_new_iter(mem, seq2, 0, -1);
+		    if (seq2 == NULL)
+		      return REG_ESPACE;
+		  }
+		else
+		  {
+		    for (i = iter->min; i < iter->max; i++)
+		      {
+			tre_ast_node_t *tmp, *copy;
+			pos_add_save = pos_add;
+			status = tre_copy_ast(mem, stack, iter->arg, 0,
+					      &pos_add, NULL, &copy, &max_pos);
+			if (status != REG_OK)
+			  return status;
+			if (seq2 != NULL)
+			  seq2 = tre_ast_new_catenation(mem, copy, seq2);
+			else
+			  seq2 = copy;
+			if (seq2 == NULL)
+			  return REG_ESPACE;
+			tmp = tre_ast_new_literal(mem, EMPTY, -1, -1);
+			if (tmp == NULL)
+			  return REG_ESPACE;
+			seq2 = tre_ast_new_union(mem, tmp, seq2);
+			if (seq2 == NULL)
+			  return REG_ESPACE;
+		      }
+		  }
+
+		pos_add = pos_add_save;
+		if (seq1 == NULL)
+		  seq1 = seq2;
+		else if (seq2 != NULL)
+		  seq1 = tre_ast_new_catenation(mem, seq1, seq2);
+		if (seq1 == NULL)
+		  return REG_ESPACE;
+		node->obj = seq1->obj;
+		node->type = seq1->type;
+	      }
+
+	    iter_depth--;
+	    pos_add_total += pos_add - pos_add_last;
+	    if (iter_depth == 0)
+	      pos_add = pos_add_total;
+
+	    break;
+	  }
+	default:
+	  assert(0);
+	  break;
+	}
+    }
+
+  *position += pos_add_total;
+
+  /* `max_pos' should never be larger than `*position' if the above
+     code works, but just an extra safeguard let's make sure
+     `*position' is set large enough so enough memory will be
+     allocated for the transition table. */
+  if (max_pos > *position)
+    *position = max_pos;
+
+#ifdef TRE_DEBUG
+  DPRINT(("Expanded AST:\n"));
+  tre_ast_print(ast);
+  DPRINT(("*position %d, max_pos %d\n", *position, max_pos));
+#endif
+
+  return status;
+}
+
+static tre_pos_and_tags_t *
+tre_set_empty(tre_mem_t mem)
+{
+  tre_pos_and_tags_t *new_set;
+
+  new_set = tre_mem_calloc(mem, sizeof(*new_set));
+  if (new_set == NULL)
+    return NULL;
+
+  new_set[0].position = -1;
+  new_set[0].code_min = -1;
+  new_set[0].code_max = -1;
+
+  return new_set;
+}
+
+static tre_pos_and_tags_t *
+tre_set_one(tre_mem_t mem, int position, int code_min, int code_max,
+	    tre_ctype_t class, tre_ctype_t *neg_classes, int backref)
+{
+  tre_pos_and_tags_t *new_set;
+
+  new_set = tre_mem_calloc(mem, sizeof(*new_set) * 2);
+  if (new_set == NULL)
+    return NULL;
+
+  new_set[0].position = position;
+  new_set[0].code_min = code_min;
+  new_set[0].code_max = code_max;
+  new_set[0].class = class;
+  new_set[0].neg_classes = neg_classes;
+  new_set[0].backref = backref;
+  new_set[1].position = -1;
+  new_set[1].code_min = -1;
+  new_set[1].code_max = -1;
+
+  return new_set;
+}
+
+static tre_pos_and_tags_t *
+tre_set_union(tre_mem_t mem, tre_pos_and_tags_t *set1, tre_pos_and_tags_t *set2,
+	      int *tags, int assertions)
+{
+  int s1, s2, i, j;
+  tre_pos_and_tags_t *new_set;
+  int *new_tags;
+  int num_tags;
+
+  for (num_tags = 0; tags != NULL && tags[num_tags] >= 0; num_tags++);
+  for (s1 = 0; set1[s1].position >= 0; s1++);
+  for (s2 = 0; set2[s2].position >= 0; s2++);
+  new_set = tre_mem_calloc(mem, sizeof(*new_set) * (s1 + s2 + 1));
+  if (!new_set )
+    return NULL;
+
+  for (s1 = 0; set1[s1].position >= 0; s1++)
+    {
+      new_set[s1].position = set1[s1].position;
+      new_set[s1].code_min = set1[s1].code_min;
+      new_set[s1].code_max = set1[s1].code_max;
+      new_set[s1].assertions = set1[s1].assertions | assertions;
+      new_set[s1].class = set1[s1].class;
+      new_set[s1].neg_classes = set1[s1].neg_classes;
+      new_set[s1].backref = set1[s1].backref;
+      if (set1[s1].tags == NULL && tags == NULL)
+	new_set[s1].tags = NULL;
+      else
+	{
+	  for (i = 0; set1[s1].tags != NULL && set1[s1].tags[i] >= 0; i++);
+	  new_tags = tre_mem_alloc(mem, (sizeof(*new_tags)
+					 * (i + num_tags + 1)));
+	  if (new_tags == NULL)
+	    return NULL;
+	  for (j = 0; j < i; j++)
+	    new_tags[j] = set1[s1].tags[j];
+	  for (i = 0; i < num_tags; i++)
+	    new_tags[j + i] = tags[i];
+	  new_tags[j + i] = -1;
+	  new_set[s1].tags = new_tags;
+	}
+    }
+
+  for (s2 = 0; set2[s2].position >= 0; s2++)
+    {
+      new_set[s1 + s2].position = set2[s2].position;
+      new_set[s1 + s2].code_min = set2[s2].code_min;
+      new_set[s1 + s2].code_max = set2[s2].code_max;
+      /* XXX - why not | assertions here as well? */
+      new_set[s1 + s2].assertions = set2[s2].assertions;
+      new_set[s1 + s2].class = set2[s2].class;
+      new_set[s1 + s2].neg_classes = set2[s2].neg_classes;
+      new_set[s1 + s2].backref = set2[s2].backref;
+      if (set2[s2].tags == NULL)
+	new_set[s1 + s2].tags = NULL;
+      else
+	{
+	  for (i = 0; set2[s2].tags[i] >= 0; i++);
+	  new_tags = tre_mem_alloc(mem, sizeof(*new_tags) * (i + 1));
+	  if (new_tags == NULL)
+	    return NULL;
+	  for (j = 0; j < i; j++)
+	    new_tags[j] = set2[s2].tags[j];
+	  new_tags[j] = -1;
+	  new_set[s1 + s2].tags = new_tags;
+	}
+    }
+  new_set[s1 + s2].position = -1;
+  return new_set;
+}
+
+/* Finds the empty path through `node' which is the one that should be
+   taken according to POSIX.2 rules, and adds the tags on that path to
+   `tags'.   `tags' may be NULL.  If `num_tags_seen' is not NULL, it is
+   set to the number of tags seen on the path. */
+static reg_errcode_t
+tre_match_empty(tre_stack_t *stack, tre_ast_node_t *node, int *tags,
+		int *assertions, int *num_tags_seen)
+{
+  tre_literal_t *lit;
+  tre_union_t *uni;
+  tre_catenation_t *cat;
+  tre_iteration_t *iter;
+  int i;
+  int bottom = tre_stack_num_objects(stack);
+  reg_errcode_t status = REG_OK;
+  if (num_tags_seen)
+    *num_tags_seen = 0;
+
+  status = tre_stack_push(stack, node);
+
+  /* Walk through the tree recursively. */
+  while (status == REG_OK && tre_stack_num_objects(stack) > bottom)
+    {
+      node = tre_stack_pop(stack);
+
+      switch (node->type)
+	{
+	case LITERAL:
+	  lit = (tre_literal_t *)node->obj;
+	  switch (lit->code_min)
+	    {
+	    case TAG:
+	      if (lit->code_max >= 0)
+		{
+		  if (tags != NULL)
+		    {
+		      /* Add the tag to `tags'. */
+		      for (i = 0; tags[i] >= 0; i++)
+			if (tags[i] == lit->code_max)
+			  break;
+		      if (tags[i] < 0)
+			{
+			  tags[i] = lit->code_max;
+			  tags[i + 1] = -1;
+			}
+		    }
+		  if (num_tags_seen)
+		    (*num_tags_seen)++;
+		}
+	      break;
+	    case ASSERTION:
+	      assert(lit->code_max >= 1
+		     || lit->code_max <= ASSERT_LAST);
+	      if (assertions != NULL)
+		*assertions |= lit->code_max;
+	      break;
+	    case EMPTY:
+	      break;
+	    default:
+	      assert(0);
+	      break;
+	    }
+	  break;
+
+	case UNION:
+	  /* Subexpressions starting earlier take priority over ones
+	     starting later, so we prefer the left subexpression over the
+	     right subexpression. */
+	  uni = (tre_union_t *)node->obj;
+	  if (uni->left->nullable)
+	    STACK_PUSHX(stack, uni->left)
+	  else if (uni->right->nullable)
+	    STACK_PUSHX(stack, uni->right)
+	  else
+	    assert(0);
+	  break;
+
+	case CATENATION:
+	  /* The path must go through both children. */
+	  cat = (tre_catenation_t *)node->obj;
+	  assert(cat->left->nullable);
+	  assert(cat->right->nullable);
+	  STACK_PUSHX(stack, cat->left);
+	  STACK_PUSHX(stack, cat->right);
+	  break;
+
+	case ITERATION:
+	  /* A match with an empty string is preferred over no match at
+	     all, so we go through the argument if possible. */
+	  iter = (tre_iteration_t *)node->obj;
+	  if (iter->arg->nullable)
+	    STACK_PUSHX(stack, iter->arg);
+	  break;
+
+	default:
+	  assert(0);
+	  break;
+	}
+    }
+
+  return status;
+}
+
+
+typedef enum {
+  NFL_RECURSE,
+  NFL_POST_UNION,
+  NFL_POST_CATENATION,
+  NFL_POST_ITERATION
+} tre_nfl_stack_symbol_t;
+
+
+/* Computes and fills in the fields `nullable', `firstpos', and `lastpos' for
+   the nodes of the AST `tree'. */
+static reg_errcode_t
+tre_compute_nfl(tre_mem_t mem, tre_stack_t *stack, tre_ast_node_t *tree)
+{
+  int bottom = tre_stack_num_objects(stack);
+
+  STACK_PUSHR(stack, tree);
+  STACK_PUSHR(stack, NFL_RECURSE);
+
+  while (tre_stack_num_objects(stack) > bottom)
+    {
+      tre_nfl_stack_symbol_t symbol;
+      tre_ast_node_t *node;
+
+      symbol = (tre_nfl_stack_symbol_t) tre_stack_pop(stack);
+      node = tre_stack_pop(stack);
+      switch (symbol)
+	{
+	case NFL_RECURSE:
+	  switch (node->type)
+	    {
+	    case LITERAL:
+	      {
+		tre_literal_t *lit = (tre_literal_t *)node->obj;
+		if (IS_BACKREF(lit))
+		  {
+		    /* Back references: nullable = false, firstpos = {i},
+		       lastpos = {i}. */
+		    node->nullable = 0;
+		    node->firstpos = tre_set_one(mem, lit->position, 0,
+					     TRE_CHAR_MAX, 0, NULL, -1);
+		    if (!node->firstpos)
+		      return REG_ESPACE;
+		    node->lastpos = tre_set_one(mem, lit->position, 0,
+						TRE_CHAR_MAX, 0, NULL,
+						lit->code_max);
+		    if (!node->lastpos)
+		      return REG_ESPACE;
+		  }
+		else if (lit->code_min < 0)
+		  {
+		    /* Tags, empty strings and zero width assertions:
+		       nullable = true, firstpos = {}, and lastpos = {}. */
+		    node->nullable = 1;
+		    node->firstpos = tre_set_empty(mem);
+		    if (!node->firstpos)
+		      return REG_ESPACE;
+		    node->lastpos = tre_set_empty(mem);
+		    if (!node->lastpos)
+		      return REG_ESPACE;
+		  }
+		else
+		  {
+		    /* Literal at position i: nullable = false, firstpos = {i},
+		       lastpos = {i}. */
+		    node->nullable = 0;
+		    node->firstpos =
+		      tre_set_one(mem, lit->position, lit->code_min,
+				  lit->code_max, 0, NULL, -1);
+		    if (!node->firstpos)
+		      return REG_ESPACE;
+		    node->lastpos = tre_set_one(mem, lit->position,
+						lit->code_min, lit->code_max,
+						lit->class, lit->neg_classes,
+						-1);
+		    if (!node->lastpos)
+		      return REG_ESPACE;
+		  }
+		break;
+	      }
+
+	    case UNION:
+	      /* Compute the attributes for the two subtrees, and after that
+		 for this node. */
+	      STACK_PUSHR(stack, node);
+	      STACK_PUSHR(stack, NFL_POST_UNION);
+	      STACK_PUSHR(stack, ((tre_union_t *)node->obj)->right);
+	      STACK_PUSHR(stack, NFL_RECURSE);
+	      STACK_PUSHR(stack, ((tre_union_t *)node->obj)->left);
+	      STACK_PUSHR(stack, NFL_RECURSE);
+	      break;
+
+	    case CATENATION:
+	      /* Compute the attributes for the two subtrees, and after that
+		 for this node. */
+	      STACK_PUSHR(stack, node);
+	      STACK_PUSHR(stack, NFL_POST_CATENATION);
+	      STACK_PUSHR(stack, ((tre_catenation_t *)node->obj)->right);
+	      STACK_PUSHR(stack, NFL_RECURSE);
+	      STACK_PUSHR(stack, ((tre_catenation_t *)node->obj)->left);
+	      STACK_PUSHR(stack, NFL_RECURSE);
+	      break;
+
+	    case ITERATION:
+	      /* Compute the attributes for the subtree, and after that for
+		 this node. */
+	      STACK_PUSHR(stack, node);
+	      STACK_PUSHR(stack, NFL_POST_ITERATION);
+	      STACK_PUSHR(stack, ((tre_iteration_t *)node->obj)->arg);
+	      STACK_PUSHR(stack, NFL_RECURSE);
+	      break;
+	    }
+	  break; /* end case: NFL_RECURSE */
+
+	case NFL_POST_UNION:
+	  {
+	    tre_union_t *uni = (tre_union_t *)node->obj;
+	    node->nullable = uni->left->nullable || uni->right->nullable;
+	    node->firstpos = tre_set_union(mem, uni->left->firstpos,
+					   uni->right->firstpos, NULL, 0);
+	    if (!node->firstpos)
+	      return REG_ESPACE;
+	    node->lastpos = tre_set_union(mem, uni->left->lastpos,
+					  uni->right->lastpos, NULL, 0);
+	    if (!node->lastpos)
+	      return REG_ESPACE;
+	    break;
+	  }
+
+	case NFL_POST_ITERATION:
+	  {
+	    tre_iteration_t *iter = (tre_iteration_t *)node->obj;
+
+	    if (iter->min == 0 || iter->arg->nullable)
+	      node->nullable = 1;
+	    else
+	      node->nullable = 0;
+	    node->firstpos = iter->arg->firstpos;
+	    node->lastpos = iter->arg->lastpos;
+	    break;
+	  }
+
+	case NFL_POST_CATENATION:
+	  {
+	    int num_tags, *tags, assertions;
+	    reg_errcode_t status;
+	    tre_catenation_t *cat = node->obj;
+	    node->nullable = cat->left->nullable && cat->right->nullable;
+
+	    /* Compute firstpos. */
+	    if (cat->left->nullable)
+	      {
+		/* The left side matches the empty string.  Make a first pass
+		   with tre_match_empty() to get the number of tags. */
+		status = tre_match_empty(stack, cat->left,
+					 NULL, NULL, &num_tags);
+		if (status != REG_OK)
+		  return status;
+		/* Allocate arrays for the tags and parameters. */
+		tags = xmalloc(sizeof(*tags) * (num_tags + 1));
+		if (!tags)
+		  return REG_ESPACE;
+		tags[0] = -1;
+		assertions = 0;
+		/* Second pass with tre_mach_empty() to get the list of
+		   tags. */
+		status = tre_match_empty(stack, cat->left, tags,
+					 &assertions, NULL);
+		if (status != REG_OK)
+		  {
+		    xfree(tags);
+		    return status;
+		  }
+		node->firstpos =
+		  tre_set_union(mem, cat->right->firstpos, cat->left->firstpos,
+				tags, assertions);
+		xfree(tags);
+		if (!node->firstpos)
+		  return REG_ESPACE;
+	      }
+	    else
+	      {
+		node->firstpos = cat->left->firstpos;
+	      }
+
+	    /* Compute lastpos. */
+	    if (cat->right->nullable)
+	      {
+		/* The right side matches the empty string.  Make a first pass
+		   with tre_match_empty() to get the number of tags. */
+		status = tre_match_empty(stack, cat->right,
+					 NULL, NULL, &num_tags);
+		if (status != REG_OK)
+		  return status;
+		/* Allocate arrays for the tags and parameters. */
+		tags = xmalloc(sizeof(int) * (num_tags + 1));
+		if (!tags)
+		  return REG_ESPACE;
+		tags[0] = -1;
+		assertions = 0;
+		/* Second pass with tre_mach_empty() to get the list of
+		   tags. */
+		status = tre_match_empty(stack, cat->right, tags,
+					 &assertions, NULL);
+		if (status != REG_OK)
+		  {
+		    xfree(tags);
+		    return status;
+		  }
+		node->lastpos =
+		  tre_set_union(mem, cat->left->lastpos, cat->right->lastpos,
+				tags, assertions);
+		xfree(tags);
+		if (!node->lastpos)
+		  return REG_ESPACE;
+	      }
+	    else
+	      {
+		node->lastpos = cat->right->lastpos;
+	      }
+	    break;
+	  }
+
+	default:
+	  assert(0);
+	  break;
+	}
+    }
+
+  return REG_OK;
+}
+
+
+/* Adds a transition from each position in `p1' to each position in `p2'. */
+static reg_errcode_t
+tre_make_trans(tre_pos_and_tags_t *p1, tre_pos_and_tags_t *p2,
+	       tre_tnfa_transition_t *transitions,
+	       int *counts, int *offs)
+{
+  tre_pos_and_tags_t *orig_p2 = p2;
+  tre_tnfa_transition_t *trans;
+  int i, j, k, l, dup, prev_p2_pos;
+
+  if (transitions != NULL)
+    while (p1->position >= 0)
+      {
+	p2 = orig_p2;
+	prev_p2_pos = -1;
+	while (p2->position >= 0)
+	  {
+	    /* Optimization: if this position was already handled, skip it. */
+	    if (p2->position == prev_p2_pos)
+	      {
+		p2++;
+		continue;
+	      }
+	    prev_p2_pos = p2->position;
+	    /* Set `trans' to point to the next unused transition from
+	       position `p1->position'. */
+	    trans = transitions + offs[p1->position];
+	    while (trans->state != NULL)
+	      {
+#if 0
+		/* If we find a previous transition from `p1->position' to
+		   `p2->position', it is overwritten.  This can happen only
+		   if there are nested loops in the regexp, like in "((a)*)*".
+		   In POSIX.2 repetition using the outer loop is always
+		   preferred over using the inner loop.	 Therefore the
+		   transition for the inner loop is useless and can be thrown
+		   away. */
+		/* XXX - The same position is used for all nodes in a bracket
+		   expression, so this optimization cannot be used (it will
+		   break bracket expressions) unless I figure out a way to
+		   detect it here. */
+		if (trans->state_id == p2->position)
+		  {
+		    DPRINT(("*"));
+		    break;
+		  }
+#endif
+		trans++;
+	      }
+
+	    if (trans->state == NULL)
+	      (trans + 1)->state = NULL;
+	    /* Use the character ranges, assertions, etc. from `p1' for
+	       the transition from `p1' to `p2'. */
+	    trans->code_min = p1->code_min;
+	    trans->code_max = p1->code_max;
+	    trans->state = transitions + offs[p2->position];
+	    trans->state_id = p2->position;
+	    trans->assertions = p1->assertions | p2->assertions
+	      | (p1->class ? ASSERT_CHAR_CLASS : 0)
+	      | (p1->neg_classes != NULL ? ASSERT_CHAR_CLASS_NEG : 0);
+	    if (p1->backref >= 0)
+	      {
+		assert((trans->assertions & ASSERT_CHAR_CLASS) == 0);
+		assert(p2->backref < 0);
+		trans->u.backref = p1->backref;
+		trans->assertions |= ASSERT_BACKREF;
+	      }
+	    else
+	      trans->u.class = p1->class;
+	    if (p1->neg_classes != NULL)
+	      {
+		for (i = 0; p1->neg_classes[i] != (tre_ctype_t)0; i++);
+		trans->neg_classes =
+		  xmalloc(sizeof(*trans->neg_classes) * (i + 1));
+		if (trans->neg_classes == NULL)
+		  return REG_ESPACE;
+		for (i = 0; p1->neg_classes[i] != (tre_ctype_t)0; i++)
+		  trans->neg_classes[i] = p1->neg_classes[i];
+		trans->neg_classes[i] = (tre_ctype_t)0;
+	      }
+	    else
+	      trans->neg_classes = NULL;
+
+	    /* Find out how many tags this transition has. */
+	    i = 0;
+	    if (p1->tags != NULL)
+	      while(p1->tags[i] >= 0)
+		i++;
+	    j = 0;
+	    if (p2->tags != NULL)
+	      while(p2->tags[j] >= 0)
+		j++;
+
+	    /* If we are overwriting a transition, free the old tag array. */
+	    if (trans->tags != NULL)
+	      xfree(trans->tags);
+	    trans->tags = NULL;
+
+	    /* If there were any tags, allocate an array and fill it. */
+	    if (i + j > 0)
+	      {
+		trans->tags = xmalloc(sizeof(*trans->tags) * (i + j + 1));
+		if (!trans->tags)
+		  return REG_ESPACE;
+		i = 0;
+		if (p1->tags != NULL)
+		  while(p1->tags[i] >= 0)
+		    {
+		      trans->tags[i] = p1->tags[i];
+		      i++;
+		    }
+		l = i;
+		j = 0;
+		if (p2->tags != NULL)
+		  while (p2->tags[j] >= 0)
+		    {
+		      /* Don't add duplicates. */
+		      dup = 0;
+		      for (k = 0; k < i; k++)
+			if (trans->tags[k] == p2->tags[j])
+			  {
+			    dup = 1;
+			    break;
+			  }
+		      if (!dup)
+			trans->tags[l++] = p2->tags[j];
+		      j++;
+		    }
+		trans->tags[l] = -1;
+	      }
+
+
+#ifdef TRE_DEBUG
+	    {
+	      int *tags;
+
+	      DPRINT(("	 %2d -> %2d on %3d", p1->position, p2->position,
+		      p1->code_min));
+	      if (p1->code_max != p1->code_min)
+		DPRINT(("-%3d", p1->code_max));
+	      tags = trans->tags;
+	      if (tags)
+		{
+		  DPRINT((", tags ["));
+		  while (*tags >= 0)
+		    {
+		      DPRINT(("%d", *tags));
+		      tags++;
+		      if (*tags >= 0)
+			DPRINT((","));
+		    }
+		  DPRINT(("]"));
+		}
+	      if (trans->assertions)
+		DPRINT((", assert %d", trans->assertions));
+	      if (trans->assertions & ASSERT_BACKREF)
+		DPRINT((", backref %d", trans->u.backref));
+	      else if (trans->class)
+		DPRINT((", class %ld", (long)trans->class));
+	      if (trans->neg_classes)
+		DPRINT((", neg_classes %p", trans->neg_classes));
+	      DPRINT(("\n"));
+	    }
+#endif /* TRE_DEBUG */
+	    p2++;
+	  }
+	p1++;
+      }
+  else
+    /* Compute a maximum limit for the number of transitions leaving
+       from each state. */
+    while (p1->position >= 0)
+      {
+	p2 = orig_p2;
+	while (p2->position >= 0)
+	  {
+	    counts[p1->position]++;
+	    p2++;
+	  }
+	p1++;
+      }
+  return REG_OK;
+}
+
+/* Converts the syntax tree to a TNFA.	All the transitions in the TNFA are
+   labelled with one character range (there are no transitions on empty
+   strings).  The TNFA takes O(n^2) space in the worst case, `n' is size of
+   the regexp. */
+static reg_errcode_t
+tre_ast_to_tnfa(tre_ast_node_t *node, tre_tnfa_transition_t *transitions,
+		int *counts, int *offs)
+{
+  tre_union_t *uni;
+  tre_catenation_t *cat;
+  tre_iteration_t *iter;
+  reg_errcode_t errcode = REG_OK;
+
+  /* XXX - recurse using a stack!. */
+  switch (node->type)
+    {
+    case LITERAL:
+      break;
+    case UNION:
+      uni = (tre_union_t *)node->obj;
+      errcode = tre_ast_to_tnfa(uni->left, transitions, counts, offs);
+      if (errcode != REG_OK)
+	return errcode;
+      errcode = tre_ast_to_tnfa(uni->right, transitions, counts, offs);
+      break;
+
+    case CATENATION:
+      cat = (tre_catenation_t *)node->obj;
+      /* Add a transition from each position in cat->left->lastpos
+	 to each position in cat->right->firstpos. */
+      errcode = tre_make_trans(cat->left->lastpos, cat->right->firstpos,
+			       transitions, counts, offs);
+      if (errcode != REG_OK)
+	return errcode;
+      errcode = tre_ast_to_tnfa(cat->left, transitions, counts, offs);
+      if (errcode != REG_OK)
+	return errcode;
+      errcode = tre_ast_to_tnfa(cat->right, transitions, counts, offs);
+      break;
+
+    case ITERATION:
+      iter = (tre_iteration_t *)node->obj;
+      assert(iter->max == -1 || iter->max == 1);
+
+      if (iter->max == -1)
+	{
+	  assert(iter->min == 0 || iter->min == 1);
+	  /* Add a transition from each last position in the iterated
+	     expression to each first position. */
+	  errcode = tre_make_trans(iter->arg->lastpos, iter->arg->firstpos,
+				   transitions, counts, offs);
+	  if (errcode != REG_OK)
+	    return errcode;
+	}
+      errcode = tre_ast_to_tnfa(iter->arg, transitions, counts, offs);
+      break;
+    }
+  return errcode;
+}
+
+
+static void
+tre_free(regex_t *preg)
+{
+  tre_tnfa_t *tnfa;
+  unsigned int i;
+  tre_tnfa_transition_t *trans;
+
+  tnfa = (void *)preg->TRE_REGEX_T_FIELD;
+  if (!tnfa)
+    return;
+
+  for (i = 0; i < tnfa->num_transitions; i++)
+    if (tnfa->transitions[i].state)
+      {
+	if (tnfa->transitions[i].tags)
+	  xfree(tnfa->transitions[i].tags);
+	if (tnfa->transitions[i].neg_classes)
+	  xfree(tnfa->transitions[i].neg_classes);
+      }
+  if (tnfa->transitions)
+    xfree(tnfa->transitions);
+
+  if (tnfa->initial)
+    {
+      for (trans = tnfa->initial; trans->state; trans++)
+	{
+	  if (trans->tags)
+	    xfree(trans->tags);
+	}
+      xfree(tnfa->initial);
+    }
+
+  if (tnfa->submatch_data)
+    {
+      for (i = 0; i < tnfa->num_submatches; i++)
+	if (tnfa->submatch_data[i].parents)
+	  xfree(tnfa->submatch_data[i].parents);
+      xfree(tnfa->submatch_data);
+    }
+
+  if (tnfa->tag_directions)
+    xfree(tnfa->tag_directions);
+  xfree(tnfa);
+}
+
+
+#define ERROR_EXIT(err)		  \
+  do				  \
+    {				  \
+      errcode = err;		  \
+      if (1) goto error_exit;	  \
+    }				  \
+ while (0)
+
+
+static int
+tre_compile(regex_t *preg, const tre_char_t *regex, size_t n, int cflags)
+{
+  tre_stack_t *stack;
+  tre_ast_node_t *tree, *tmp_ast_l, *tmp_ast_r;
+  tre_pos_and_tags_t *p;
+  int *counts = NULL, *offs = NULL;
+  int i, add = 0;
+  tre_tnfa_transition_t *transitions, *initial;
+  tre_tnfa_t *tnfa = NULL;
+  tre_submatch_data_t *submatch_data;
+  tre_tag_direction_t *tag_directions = NULL;
+  reg_errcode_t errcode;
+  tre_mem_t mem;
+
+  /* Parse context. */
+  tre_parse_ctx_t parse_ctx;
+
+  /* Allocate a stack used throughout the compilation process for various
+     purposes. */
+  stack = tre_stack_new(512, 10240, 128);
+  if (!stack)
+    return REG_ESPACE;
+  /* Allocate a fast memory allocator. */
+  mem = tre_mem_new();
+  if (!mem)
+    {
+      tre_stack_destroy(stack);
+      return REG_ESPACE;
+    }
+
+  /* Parse the regexp. */
+  memset(&parse_ctx, 0, sizeof(parse_ctx));
+  parse_ctx.mem = mem;
+  parse_ctx.stack = stack;
+  parse_ctx.re = regex;
+  parse_ctx.len = n;
+  parse_ctx.cflags = cflags;
+  parse_ctx.max_backref = -1;
+  DPRINT(("tre_compile: parsing '%.*" STRF "'\n", n, regex));
+  errcode = tre_parse(&parse_ctx);
+  if (errcode != REG_OK)
+    ERROR_EXIT(errcode);
+  preg->re_nsub = parse_ctx.submatch_id - 1;
+  tree = parse_ctx.result;
+
+#ifdef TRE_DEBUG
+  tre_ast_print(tree);
+#endif /* TRE_DEBUG */
+
+  /* Referring to nonexistent subexpressions is illegal. */
+  if (parse_ctx.max_backref > (int)preg->re_nsub)
+    ERROR_EXIT(REG_ESUBREG);
+
+  /* Allocate the TNFA struct. */
+  tnfa = xcalloc(1, sizeof(tre_tnfa_t));
+  if (tnfa == NULL)
+    ERROR_EXIT(REG_ESPACE);
+  tnfa->have_backrefs = parse_ctx.max_backref >= 0;
+  tnfa->num_submatches = parse_ctx.submatch_id;
+
+  /* Set up tags for submatch addressing.  If REG_NOSUB is set and the
+     regexp does not have back references, this can be skipped. */
+  if (tnfa->have_backrefs || !(cflags & REG_NOSUB))
+    {
+      DPRINT(("tre_compile: setting up tags\n"));
+
+      /* Figure out how many tags we will need. */
+      errcode = tre_add_tags(NULL, stack, tree, tnfa);
+      if (errcode != REG_OK)
+	ERROR_EXIT(errcode);
+#ifdef TRE_DEBUG
+      tre_ast_print(tree);
+#endif /* TRE_DEBUG */
+
+      if (tnfa->num_tags > 0)
+	{
+	  tag_directions = xmalloc(sizeof(*tag_directions)
+				   * (tnfa->num_tags + 1));
+	  if (tag_directions == NULL)
+	    ERROR_EXIT(REG_ESPACE);
+	  tnfa->tag_directions = tag_directions;
+	  memset(tag_directions, -1,
+		 sizeof(*tag_directions) * (tnfa->num_tags + 1));
+	}
+
+      submatch_data = xcalloc(parse_ctx.submatch_id, sizeof(*submatch_data));
+      if (submatch_data == NULL)
+	ERROR_EXIT(REG_ESPACE);
+      tnfa->submatch_data = submatch_data;
+
+      errcode = tre_add_tags(mem, stack, tree, tnfa);
+      if (errcode != REG_OK)
+	ERROR_EXIT(errcode);
+
+#ifdef TRE_DEBUG
+      for (i = 0; i < parse_ctx.submatch_id; i++)
+	DPRINT(("pmatch[%d] = {t%d, t%d}\n",
+		i, submatch_data[i].so_tag, submatch_data[i].eo_tag));
+      for (i = 0; i < tnfa->num_tags; i++)
+	DPRINT(("t%d is %s\n", i,
+		tag_directions[i] == TRE_TAG_MINIMIZE ?
+		"minimized" : "maximized"));
+#endif /* TRE_DEBUG */
+    }
+
+  /* Expand iteration nodes. */
+  errcode = tre_expand_ast(mem, stack, tree, &parse_ctx.position,
+			   tag_directions, NULL);
+  if (errcode != REG_OK)
+    ERROR_EXIT(errcode);
+
+  /* Add a dummy node for the final state.
+     XXX - For certain patterns this dummy node can be optimized away,
+	   for example "a*" or "ab*".	Figure out a simple way to detect
+	   this possibility. */
+  tmp_ast_l = tree;
+  tmp_ast_r = tre_ast_new_literal(mem, 0, 0, parse_ctx.position++);
+  if (tmp_ast_r == NULL)
+    ERROR_EXIT(REG_ESPACE);
+
+  tree = tre_ast_new_catenation(mem, tmp_ast_l, tmp_ast_r);
+  if (tree == NULL)
+    ERROR_EXIT(REG_ESPACE);
+
+#ifdef TRE_DEBUG
+  tre_ast_print(tree);
+  DPRINT(("Number of states: %d\n", parse_ctx.position));
+#endif /* TRE_DEBUG */
+
+  errcode = tre_compute_nfl(mem, stack, tree);
+  if (errcode != REG_OK)
+    ERROR_EXIT(errcode);
+
+  counts = xmalloc(sizeof(int) * parse_ctx.position);
+  if (counts == NULL)
+    ERROR_EXIT(REG_ESPACE);
+
+  offs = xmalloc(sizeof(int) * parse_ctx.position);
+  if (offs == NULL)
+    ERROR_EXIT(REG_ESPACE);
+
+  for (i = 0; i < parse_ctx.position; i++)
+    counts[i] = 0;
+  tre_ast_to_tnfa(tree, NULL, counts, NULL);
+
+  add = 0;
+  for (i = 0; i < parse_ctx.position; i++)
+    {
+      offs[i] = add;
+      add += counts[i] + 1;
+      counts[i] = 0;
+    }
+  transitions = xcalloc(add + 1, sizeof(*transitions));
+  if (transitions == NULL)
+    ERROR_EXIT(REG_ESPACE);
+  tnfa->transitions = transitions;
+  tnfa->num_transitions = add;
+
+  DPRINT(("Converting to TNFA:\n"));
+  errcode = tre_ast_to_tnfa(tree, transitions, counts, offs);
+  if (errcode != REG_OK)
+    ERROR_EXIT(errcode);
+
+  p = tree->firstpos;
+  i = 0;
+  while (p->position >= 0)
+    {
+      i++;
+
+#ifdef TRE_DEBUG
+      {
+	int *tags;
+	DPRINT(("initial: %d", p->position));
+	tags = p->tags;
+	if (tags != NULL)
+	  {
+	    if (*tags >= 0)
+	      DPRINT(("/"));
+	    while (*tags >= 0)
+	      {
+		DPRINT(("%d", *tags));
+		tags++;
+		if (*tags >= 0)
+		  DPRINT((","));
+	      }
+	  }
+	DPRINT((", assert %d", p->assertions));
+	DPRINT(("\n"));
+      }
+#endif /* TRE_DEBUG */
+
+      p++;
+    }
+
+  initial = xcalloc(i + 1, sizeof(tre_tnfa_transition_t));
+  if (initial == NULL)
+    ERROR_EXIT(REG_ESPACE);
+  tnfa->initial = initial;
+
+  i = 0;
+  for (p = tree->firstpos; p->position >= 0; p++)
+    {
+      initial[i].state = transitions + offs[p->position];
+      initial[i].state_id = p->position;
+      initial[i].tags = NULL;
+      /* Copy the arrays p->tags, they are allocated
+	 from a tre_mem object. */
+      if (p->tags)
+	{
+	  int j;
+	  for (j = 0; p->tags[j] >= 0; j++);
+	  initial[i].tags = xmalloc(sizeof(*p->tags) * (j + 1));
+	  if (!initial[i].tags)
+	    ERROR_EXIT(REG_ESPACE);
+	  memcpy(initial[i].tags, p->tags, sizeof(*p->tags) * (j + 1));
+	}
+      initial[i].assertions = p->assertions;
+      i++;
+    }
+  initial[i].state = NULL;
+
+  tnfa->num_transitions = add;
+  tnfa->final = transitions + offs[tree->lastpos[0].position];
+  tnfa->num_states = parse_ctx.position;
+  tnfa->cflags = cflags;
+
+  DPRINT(("final state %p\n", (void *)tnfa->final));
+
+  tre_mem_destroy(mem);
+  tre_stack_destroy(stack);
+  xfree(counts);
+  xfree(offs);
+
+  preg->TRE_REGEX_T_FIELD = (void *)tnfa;
+  return REG_OK;
+
+ error_exit:
+  /* Free everything that was allocated and return the error code. */
+  tre_mem_destroy(mem);
+  if (stack != NULL)
+    tre_stack_destroy(stack);
+  if (counts != NULL)
+    xfree(counts);
+  if (offs != NULL)
+    xfree(offs);
+  preg->TRE_REGEX_T_FIELD = (void *)tnfa;
+  tre_free(preg);
+  return errcode;
+}
+
+
+/***********************************************************************
+ from regcomp.c
+***********************************************************************/
+
+int
+regcomp(regex_t *preg, const char *regex, int cflags)
+{
+  int ret;
+  tre_char_t *wregex;
+  size_t n = strlen(regex);
+
+  if (n+1 > SIZE_MAX/sizeof(tre_char_t))
+    return REG_ESPACE;
+  wregex = xmalloc(sizeof(tre_char_t) * (n + 1));
+  if (wregex == NULL)
+    return REG_ESPACE;
+
+  n = mbstowcs(wregex, regex, n+1);
+  if (n == (size_t)-1) {
+    xfree(wregex);
+    return REG_BADPAT;
+  }
+
+  ret = tre_compile(preg, wregex, n, cflags);
+  xfree(wregex);
+
+  return ret;
+}
+
+void
+regfree(regex_t *preg)
+{
+  tre_free(preg);
+}
+
+/* EOF */