text: /* Produced by texiweb from libavl.w. */
  
  /* libavl - library for manipulation of binary trees.
   Copyright (C) 1998-2002, 2004 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 of the
   License, 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 program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
   02111-1307, USA.
  
   The author may be contacted at <blp@gnu.org> on the Internet, or
   write to Ben Pfaff, Stanford University, Computer Science Dept., 353
   Serra Mall, Stanford CA 94305, USA.
   */
  
  #include <assert.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include "avl.h"
  #include "fastCMaths.h"
  #include "sonLibGlobalsInternal.h"
  
  /* Creates and returns a new table
   with comparison function |compare| using parameter |param|
   and memory allocator |allocator|.
   Returns |NULL| if memory allocation failed. */
  struct avl_table *
  avl_create(avl_comparison_func *compare, void *param,
          struct libavl_allocator *allocator) {
      struct avl_table *tree;
  
      assert (compare != NULL);
  
      if (allocator == NULL)
          allocator = &avl_allocator_default;
  
      tree = allocator->libavl_malloc(allocator, sizeof *tree);
      assert(tree != NULL);
      if (tree == NULL)
          return NULL;
  
      tree->avl_root = NULL;
      tree->avl_compare = compare;
      tree->avl_param = param;
      tree->avl_alloc = allocator;
      tree->avl_count = 0;
      tree->avl_generation = 0;
  
      return tree;
  }
  
  /* Search |tree| for an item matching |item|, and return it if found.
   Otherwise return |NULL|. */
  void *
  avl_find(const struct avl_table *tree, const void *item) {
      const struct avl_node *p;
  
      assert (tree != NULL && item != NULL);
      for (p = tree->avl_root; p != NULL;) {
          int32_t cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
  
          if (cmp < 0)
              p = p->avl_link[0];
          else if (cmp > 0)
              p = p->avl_link[1];
          else
              /* |cmp == 0| */
              return p->avl_data;
      }
  
      return NULL;
  }
  
  /* Search in |tree| for the object minimally less than |item|, and return it if found.
   Otherwise return |NULL| if no object less than |item| */
  void *
  avl_find_lessThan(const struct avl_table *tree, const void *item) {
      const struct avl_node *p;
  
      assert (tree != NULL && item != NULL);
      void *lessThan = NULL;
      for (p = tree->avl_root; p != NULL;) {
          int32_t cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
  
          if (cmp <= 0) {
              p = p->avl_link[0];
          } else { // cmp > 0
              lessThan = p->avl_data;
              p = p->avl_link[1];
          }
      }
  
      return lessThan;
  }
  
  /* Search in |tree| for the object minimally less than |item|, and return it if found.
   Otherwise return |NULL| if no object less than |item| */
  void *
  avl_find_lessThanOrEqual(const struct avl_table *tree, const void *item) {
      const struct avl_node *p;
  
      assert (tree != NULL && item != NULL);
      void *lessThan = NULL;
      for (p = tree->avl_root; p != NULL;) {
          int32_t cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
  
          if (cmp < 0) {
              p = p->avl_link[0];
          } else if(cmp > 0) {
              lessThan = p->avl_data;
              p = p->avl_link[1];
          }
          else {
              return p->avl_data;
          }
      }
  
      return lessThan;
  }
  
  /* Search in |tree| for the object minimally greater than |item|, and return it if found.
   Otherwise return |NULL|. */
  void *
  avl_find_greaterThan(const struct avl_table *tree, const void *item) {
      const struct avl_node *p;
  
      assert (tree != NULL && item != NULL);
      void *greaterThan = NULL;
      for (p = tree->avl_root; p != NULL;) {
          int32_t cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
  
          if (cmp >= 0) {
              p = p->avl_link[1];
          } else { // cmp < 0
              greaterThan = p->avl_data;
              p = p->avl_link[0];
          }
      }
  
      return greaterThan;
  }
  
  /* Search in |tree| for the object equal or minimally greater than |item|, and return it if found.
   Otherwise return |NULL|. */
  void *
  avl_find_greaterThanOrEqual(const struct avl_table *tree, const void *item) {
      const struct avl_node *p;
  
      assert (tree != NULL && item != NULL);
      void *greaterThan = NULL;
      for (p = tree->avl_root; p != NULL;) {
          int32_t cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
  
          if (cmp > 0) {
              p = p->avl_link[1];
          } else if(cmp < 0) {
              greaterThan = p->avl_data;
              p = p->avl_link[0];
          }
          else {
              return p->avl_data;
          }
      }
  
      return greaterThan;
  }
  
  /* Inserts |item| INT_32o |tree| and returns a poINT_32er to |item|'s address.
   If a duplicate item is found in the tree,
   returns a poINT_32er to the duplicate without inserting |item|.
   Returns |NULL| in case of memory allocation failure. */
  void **
  avl_probe(struct avl_table *tree, void *item) {
      struct avl_node *y, *z; /* Top node to update balance factor, and parent. */
      struct avl_node *p, *q; /* Iterator, and parent. */
      struct avl_node *n; /* Newly inserted node. */
      struct avl_node *w; /* New root of rebalanced subtree. */
      int32_t dir; /* Direction to descend. */
  
      unsigned char da[AVL_MAX_HEIGHT]; /* Cached comparison results. */
      int32_t k = 0; /* Number of cached results. */
  
      assert (tree != NULL && item != NULL);
  
      z = (struct avl_node *) &tree->avl_root;
      y = tree->avl_root;
      dir = 0;
      for (q = z, p = y; p != NULL; q = p, p = p->avl_link[dir]) {
          int32_t cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
          if (cmp == 0)
              return &p->avl_data;
  
          if (p->avl_balance != 0)
              z = q, y = p, k = 0;
          da[k++] = dir = cmp > 0;
      }
  
      n = q->avl_link[dir] = tree->avl_alloc->libavl_malloc(tree->avl_alloc,
              sizeof *n);
      if (n == NULL)
          return NULL;
  
      tree->avl_count++;
      n->avl_data = item;
      n->avl_link[0] = n->avl_link[1] = NULL;
      n->avl_balance = 0;
      if (y == NULL)
          return &n->avl_data;
  
      for (p = y, k = 0; p != n; p = p->avl_link[da[k]], k++)
          if (da[k] == 0)
              p->avl_balance--;
          else
              p->avl_balance++;
  
      if (y->avl_balance == -2) {
          struct avl_node *x = y->avl_link[0];
          if (x->avl_balance == -1) {
              w = x;
              y->avl_link[0] = x->avl_link[1];
              x->avl_link[1] = y;
              x->avl_balance = y->avl_balance = 0;
          } else {
              assert (x->avl_balance == +1);
              w = x->avl_link[1];
              x->avl_link[1] = w->avl_link[0];
              w->avl_link[0] = x;
              y->avl_link[0] = w->avl_link[1];
              w->avl_link[1] = y;
              if (w->avl_balance == -1)
                  x->avl_balance = 0, y->avl_balance = +1;
              else if (w->avl_balance == 0)
                  x->avl_balance = y->avl_balance = 0;
              else
                  /* |w->avl_balance == +1| */
                  x->avl_balance = -1, y->avl_balance = 0;
              w->avl_balance = 0;
          }
      } else if (y->avl_balance == +2) {
          struct avl_node *x = y->avl_link[1];
          if (x->avl_balance == +1) {
              w = x;
              y->avl_link[1] = x->avl_link[0];
              x->avl_link[0] = y;
              x->avl_balance = y->avl_balance = 0;
          } else {
              assert (x->avl_balance == -1);
              w = x->avl_link[0];
              x->avl_link[0] = w->avl_link[1];
              w->avl_link[1] = x;
              y->avl_link[1] = w->avl_link[0];
              w->avl_link[0] = y;
              if (w->avl_balance == +1)
                  x->avl_balance = 0, y->avl_balance = -1;
              else if (w->avl_balance == 0)
                  x->avl_balance = y->avl_balance = 0;
              else
                  /* |w->avl_balance == -1| */
                  x->avl_balance = +1, y->avl_balance = 0;
              w->avl_balance = 0;
          }
      } else
          return &n->avl_data;
      z->avl_link[y != z->avl_link[0]] = w;
  
      tree->avl_generation++;
      return &n->avl_data;
  }
  
  /* Inserts |item| INT_32o |table|.
   Returns |NULL| if |item| was successfully inserted
   or if a memory allocation error occurred.
   Otherwise, returns the duplicate item. */
  void *
  avl_insert(struct avl_table *table, void *item) {
      void **p = avl_probe(table, item);
      return p == NULL || *p == item ? NULL : *p;
  }
  
  /* Inserts |item| INT_32o |table|, replacing any duplicate item.
   Returns |NULL| if |item| was inserted without replacing a duplicate,
   or if a memory allocation error occurred.
   Otherwise, returns the item that was replaced. */
  void *
  avl_replace(struct avl_table *table, void *item) {
      void **p = avl_probe(table, item);
      if (p == NULL || *p == item)
          return NULL;
      else {
          void *r = *p;
          *p = item;
          return r;
      }
  }
  
  /* Deletes from |tree| and returns an item matching |item|.
   Returns a null poINT_32er if no matching item found. */
  void *
  avl_delete(struct avl_table *tree, const void *item) {
      /* Stack of nodes. */
      struct avl_node *pa[AVL_MAX_HEIGHT]; /* Nodes. */
      unsigned char da[AVL_MAX_HEIGHT]; /* |avl_link[]| indexes. */
      int32_t k; /* Stack poINT_32er. */
  
      struct avl_node *p; /* Traverses tree to find node to delete. */
      int32_t cmp; /* Result of comparison between |item| and |p|. */
  
      assert (tree != NULL && item != NULL);
  
      k = 0;
      p = (struct avl_node *) &tree->avl_root;
      for (cmp = -1; cmp != 0; cmp = tree->avl_compare(item, p->avl_data,
              tree->avl_param)) {
          int32_t dir = cmp > 0;
  
          pa[k] = p;
          da[k++] = dir;
  
          p = p->avl_link[dir];
          if (p == NULL)
              return NULL;
      }
      item = p->avl_data;
  
      if (p->avl_link[1] == NULL)
          pa[k - 1]->avl_link[da[k - 1]] = p->avl_link[0];
      else {
          struct avl_node *r = p->avl_link[1];
          if (r->avl_link[0] == NULL) {
              r->avl_link[0] = p->avl_link[0];
              r->avl_balance = p->avl_balance;
              pa[k - 1]->avl_link[da[k - 1]] = r;
              da[k] = 1;
              pa[k++] = r;
          } else {
              struct avl_node *s;
              int32_t j = k++;
  
              for (;;) {
                  da[k] = 0;
                  pa[k++] = r;
                  s = r->avl_link[0];
                  if (s->avl_link[0] == NULL)
                      break;
  
                  r = s;
              }
  
              s->avl_link[0] = p->avl_link[0];
              r->avl_link[0] = s->avl_link[1];
              s->avl_link[1] = p->avl_link[1];
              s->avl_balance = p->avl_balance;
  
              pa[j - 1]->avl_link[da[j - 1]] = s;
              da[j] = 1;
              pa[j] = s;
          }
      }
  
      tree->avl_alloc->libavl_free(tree->avl_alloc, p);
  
      assert (k> 0);
      while (--k > 0) {
          struct avl_node *y = pa[k];
  
          if (da[k] == 0) {
              y->avl_balance++;
              if (y->avl_balance == +1)
                  break;
              else if (y->avl_balance == +2) {
                  struct avl_node *x = y->avl_link[1];
                  if (x->avl_balance == -1) {
                      struct avl_node *w;
                      assert (x->avl_balance == -1);
                      w = x->avl_link[0];
                      x->avl_link[0] = w->avl_link[1];
                      w->avl_link[1] = x;
                      y->avl_link[1] = w->avl_link[0];
                      w->avl_link[0] = y;
                      if (w->avl_balance == +1)
                          x->avl_balance = 0, y->avl_balance = -1;
                      else if (w->avl_balance == 0)
                          x->avl_balance = y->avl_balance = 0;
                      else
                          /* |w->avl_balance == -1| */
                          x->avl_balance = +1, y->avl_balance = 0;
                      w->avl_balance = 0;
                      pa[k - 1]->avl_link[da[k - 1]] = w;
                  } else {
                      y->avl_link[1] = x->avl_link[0];
                      x->avl_link[0] = y;
                      pa[k - 1]->avl_link[da[k - 1]] = x;
                      if (x->avl_balance == 0) {
                          x->avl_balance = -1;
                          y->avl_balance = +1;
                          break;
                      } else
                          x->avl_balance = y->avl_balance = 0;
                  }
              }
          } else {
              y->avl_balance--;
              if (y->avl_balance == -1)
                  break;
              else if (y->avl_balance == -2) {
                  struct avl_node *x = y->avl_link[0];
                  if (x->avl_balance == +1) {
                      struct avl_node *w;
                      assert (x->avl_balance == +1);
                      w = x->avl_link[1];
                      x->avl_link[1] = w->avl_link[0];
                      w->avl_link[0] = x;
                      y->avl_link[0] = w->avl_link[1];
                      w->avl_link[1] = y;
                      if (w->avl_balance == -1)
                          x->avl_balance = 0, y->avl_balance = +1;
                      else if (w->avl_balance == 0)
                          x->avl_balance = y->avl_balance = 0;
                      else
                          /* |w->avl_balance == +1| */
                          x->avl_balance = -1, y->avl_balance = 0;
                      w->avl_balance = 0;
                      pa[k - 1]->avl_link[da[k - 1]] = w;
                  } else {
                      y->avl_link[0] = x->avl_link[1];
                      x->avl_link[1] = y;
                      pa[k - 1]->avl_link[da[k - 1]] = x;
                      if (x->avl_balance == 0) {
                          x->avl_balance = +1;
                          y->avl_balance = -1;
                          break;
                      } else
                          x->avl_balance = y->avl_balance = 0;
                  }
              }
          }
      }
  
      tree->avl_count--;
      tree->avl_generation++;
      return (void *) item;
  }
  
  /* Refreshes the stack of parent poINT_32ers in |trav|
   and updates its generation number. */
  static void trav_refresh(struct avl_traverser *trav) {
      assert (trav != NULL);
  
      trav->avl_generation = trav->avl_table->avl_generation;
  
      if (trav->avl_node != NULL) {
          avl_comparison_func *cmp = trav->avl_table->avl_compare;
          void *param = trav->avl_table->avl_param;
          struct avl_node *node = trav->avl_node;
          struct avl_node *i;
  
          trav->avl_height = 0;
          for (i = trav->avl_table->avl_root; i != node;) {
              assert (trav->avl_height < AVL_MAX_HEIGHT);
              assert (i != NULL);
  
              trav->avl_stack[trav->avl_height++] = i;
              i = i->avl_link[cmp(node->avl_data, i->avl_data, param) > 0];
          }
      }
  }
  
  /* Initializes |trav| for use with |tree|
   and selects the null node. */
  void avl_t_init(struct avl_traverser *trav, struct avl_table *tree) {
      trav->avl_table = tree;
      trav->avl_node = NULL;
      trav->avl_height = 0;
      trav->avl_generation = tree->avl_generation;
  }
  
  /* Initializes |trav| for |tree|
   and selects and returns a poINT_32er to its least-valued item.
   Returns |NULL| if |tree| contains no nodes. */
  void *
  avl_t_first(struct avl_traverser *trav, struct avl_table *tree) {
      struct avl_node *x;
  
      assert (tree != NULL && trav != NULL);
  
      trav->avl_table = tree;
      trav->avl_height = 0;
      trav->avl_generation = tree->avl_generation;
  
      x = tree->avl_root;
      if (x != NULL)
          while (x->avl_link[0] != NULL) {
              assert (trav->avl_height < AVL_MAX_HEIGHT);
              trav->avl_stack[trav->avl_height++] = x;
              x = x->avl_link[0];
          }
      trav->avl_node = x;
  
      return x != NULL ? x->avl_data : NULL;
  }
  
  /* Initializes |trav| for |tree|
   and selects and returns a poINT_32er to its greatest-valued item.
   Returns |NULL| if |tree| contains no nodes. */
  void *
  avl_t_last(struct avl_traverser *trav, struct avl_table *tree) {
      struct avl_node *x;
  
      assert (tree != NULL && trav != NULL);
  
      trav->avl_table = tree;
      trav->avl_height = 0;
      trav->avl_generation = tree->avl_generation;
  
      x = tree->avl_root;
      if (x != NULL)
          while (x->avl_link[1] != NULL) {
              assert (trav->avl_height < AVL_MAX_HEIGHT);
              trav->avl_stack[trav->avl_height++] = x;
              x = x->avl_link[1];
          }
      trav->avl_node = x;
  
      return x != NULL ? x->avl_data : NULL;
  }
  
  /* Searches for |item| in |tree|.
   If found, initializes |trav| to the item found and returns the item
   as well.
   If there is no matching item, initializes |trav| to the null item
   and returns |NULL|. */
  void *
  avl_t_find(struct avl_traverser *trav, struct avl_table *tree, void *item) {
      struct avl_node *p, *q;
  
      assert (trav != NULL && tree != NULL && item != NULL);
      trav->avl_table = tree;
      trav->avl_height = 0;
      trav->avl_generation = tree->avl_generation;
      for (p = tree->avl_root; p != NULL; p = q) {
          int32_t cmp = tree->avl_compare(item, p->avl_data, tree->avl_param);
  
          if (cmp < 0)
              q = p->avl_link[0];
          else if (cmp > 0)
              q = p->avl_link[1];
          else /* |cmp == 0| */
          {
              trav->avl_node = p;
              return p->avl_data;
          }
  
          assert (trav->avl_height < AVL_MAX_HEIGHT);
          trav->avl_stack[trav->avl_height++] = p;
      }
  
      trav->avl_height = 0;
      trav->avl_node = NULL;
      return NULL;
  }
  
  /* Attempts to insert |item| INT_32o |tree|.
   If |item| is inserted successfully, it is returned and |trav| is
   initialized to its location.
   If a duplicate is found, it is returned and |trav| is initialized to
   its location.  No replacement of the item occurs.
   If a memory allocation failure occurs, |NULL| is returned and |trav|
   is initialized to the null item. */
  void *
  avl_t_insert(struct avl_traverser *trav, struct avl_table *tree, void *item) {
      void **p;
  
      assert (trav != NULL && tree != NULL && item != NULL);
  
      p = avl_probe(tree, item);
      if (p != NULL) {
          trav->avl_table = tree;trav->avl_node =
          ((struct avl_node *)
                  ((char *) p - offsetof (struct avl_node, avl_data)));
          trav->avl_generation = tree->avl_generation - 1;
          return *p;
      } else {
          avl_t_init(trav, tree);
          return NULL;
      }
  }
  
  /* Initializes |trav| to have the same current node as |src|. */
  void *
  avl_t_copy(struct avl_traverser *trav, const struct avl_traverser *src) {
      assert (trav != NULL && src != NULL);
  
      if (trav != src) {
          trav->avl_table = src->avl_table;
          trav->avl_node = src->avl_node;
          trav->avl_generation = src->avl_generation;
          if (trav->avl_generation == trav->avl_table->avl_generation) {
              trav->avl_height = src->avl_height;
              memcpy(trav->avl_stack, (const void *) src->avl_stack,
                      sizeof *trav->avl_stack * trav->avl_height);
          }
      }
  
      return trav->avl_node != NULL ? trav->avl_node->avl_data : NULL;
  }
  
  /* Returns the next data item in inorder
   within the tree being traversed with |trav|,
   or if there are no more data items returns |NULL|. */
  void *
  avl_t_next(struct avl_traverser *trav) {
      struct avl_node *x;
  
      assert (trav != NULL);
  
      if (trav->avl_generation != trav->avl_table->avl_generation)
          trav_refresh(trav);
  
      x = trav->avl_node;
      if (x == NULL) {
          return avl_t_first(trav, trav->avl_table);
      } else if (x->avl_link[1] != NULL) {
          assert (trav->avl_height < AVL_MAX_HEIGHT);
          trav->avl_stack[trav->avl_height++] = x;
          x = x->avl_link[1];
  
          while (x->avl_link[0] != NULL) {
              assert (trav->avl_height < AVL_MAX_HEIGHT);
              trav->avl_stack[trav->avl_height++] = x;
              x = x->avl_link[0];
          }
      } else {
          struct avl_node *y;
  
          do {
              if (trav->avl_height == 0) {
                  trav->avl_node = NULL;
                  return NULL;
              }
  
              y = x;
              x = trav->avl_stack[--trav->avl_height];
          } while (y == x->avl_link[1]);
      }
      trav->avl_node = x;
  
      return x->avl_data;
  }
  
  /* Returns the previous data item in inorder
   within the tree being traversed with |trav|,
   or if there are no more data items returns |NULL|. */
  void *
  avl_t_prev(struct avl_traverser *trav) {
      struct avl_node *x;
  
      assert (trav != NULL);
  
      if (trav->avl_generation != trav->avl_table->avl_generation)
          trav_refresh(trav);
  
      x = trav->avl_node;
      if (x == NULL) {
          return avl_t_last(trav, trav->avl_table);
      } else if (x->avl_link[0] != NULL) {
          assert (trav->avl_height < AVL_MAX_HEIGHT);
          trav->avl_stack[trav->avl_height++] = x;
          x = x->avl_link[0];
  
          while (x->avl_link[1] != NULL) {
              assert (trav->avl_height < AVL_MAX_HEIGHT);
              trav->avl_stack[trav->avl_height++] = x;
              x = x->avl_link[1];
          }
      } else {
          struct avl_node *y;
  
          do {
              if (trav->avl_height == 0) {
                  trav->avl_node = NULL;
                  return NULL;
              }
  
              y = x;
              x = trav->avl_stack[--trav->avl_height];
          } while (y == x->avl_link[0]);
      }
      trav->avl_node = x;
  
      return x->avl_data;
  }
  
  /* Returns |trav|'s current item. */
  void *
  avl_t_cur(struct avl_traverser *trav) {
      assert (trav != NULL);
  
      return trav->avl_node != NULL ? trav->avl_node->avl_data : NULL;
  }
  
  /* Replaces the current item in |trav| by |new| and returns the item replaced.
   |trav| must not have the null item selected.
   The new item must not upset the ordering of the tree. */
  void *
  avl_t_replace(struct avl_traverser *trav, void *new) {
      void *old;
  
      assert (trav != NULL && trav->avl_node != NULL && new != NULL);
      old = trav->avl_node->avl_data;
      trav->avl_node->avl_data = new;
      return old;
  }
  
  /* Destroys |new| with |avl_destroy (new, destroy)|,
   first setting right links of nodes in |stack| within |new|
   to null poINT_32ers to avoid touching uninitialized data. */
  static void copy_error_recovery(struct avl_node **stack, int32_t height,
          struct avl_table *new, avl_item_func *destroy) {
      assert (stack != NULL && height >= 0 && new != NULL);
  
      for (; height > 2; height -= 2)
          stack[height - 1]->avl_link[1] = NULL;
      avl_destroy(new, destroy);
  }
  
  /* Copies |org| to a newly created tree, which is returned.
   If |copy != NULL|, each data item in |org| is first passed to |copy|,
   and the return values are inserted INT_32o the tree,
   with |NULL| return values taken as indications of failure.
   On failure, destroys the partially created new tree,
   applying |destroy|, if non-null, to each item in the new tree so far,
   and returns |NULL|.
   If |allocator != NULL|, it is used for allocation in the new tree.
   Otherwise, the same allocator used for |org| is used. */
  struct avl_table *
  avl_copy(const struct avl_table *org, avl_copy_func *copy,
          avl_item_func *destroy, struct libavl_allocator *allocator) {
      struct avl_node *stack[2 * (AVL_MAX_HEIGHT + 1)];
      int32_t height = 0;
  
      struct avl_table *new;
      const struct avl_node *x;
      struct avl_node *y;
  
      assert (org != NULL);
      new = avl_create(org->avl_compare, org->avl_param,
              allocator != NULL ? allocator : org->avl_alloc);
      if (new == NULL)
          return NULL;
      new->avl_count = org->avl_count;
      if (new->avl_count == 0)
          return new;
  
      x = (const struct avl_node *) &org->avl_root;
      y = (struct avl_node *) &new->avl_root;
      for (;;) {
          while (x->avl_link[0] != NULL) {
              assert (height < 2 * (AVL_MAX_HEIGHT + 1));
  
              y->avl_link[0] = new->avl_alloc->libavl_malloc(new->avl_alloc,
                      sizeof *y->avl_link[0]);
              if (y->avl_link[0] == NULL) {
                  if (y != (struct avl_node *) &new->avl_root) {
                      y->avl_data = NULL;
                      y->avl_link[1] = NULL;
                  }
  
                  copy_error_recovery(stack, height, new, destroy);
                  return NULL;
              }
  
              stack[height++] = (struct avl_node *) x;
              stack[height++] = y;
              x = x->avl_link[0];
              y = y->avl_link[0];
          }
          y->avl_link[0] = NULL;
  
          for (;;) {
              y->avl_balance = x->avl_balance;
              if (copy == NULL)
                  y->avl_data = x->avl_data;
              else {
                  y->avl_data = copy(x->avl_data, org->avl_param);
                  if (y->avl_data == NULL) {
                      y->avl_link[1] = NULL;
                      copy_error_recovery(stack, height, new, destroy);
                      return NULL;
                  }
              }
  
              if (x->avl_link[1] != NULL) {
                  y->avl_link[1] = new->avl_alloc->libavl_malloc(new->avl_alloc,
                          sizeof *y->avl_link[1]);
                  if (y->avl_link[1] == NULL) {
                      copy_error_recovery(stack, height, new, destroy);
                      return NULL;
                  }
  
                  x = x->avl_link[1];
                  y = y->avl_link[1];
                  break;
              } else
                  y->avl_link[1] = NULL;
  
              if (height <= 2)
                  return new;
  
              y = stack[--height];
              x = stack[--height];
          }
      }
  }
  
  /* Frees storage allocated for |tree|.
   If |destroy != NULL|, applies it to each data item in inorder. */
  void avl_destroy(struct avl_table *tree, avl_item_func *destroy) {
      struct avl_node *p, *q;
  
      assert (tree != NULL);
  
      for (p = tree->avl_root; p != NULL; p = q)
          if (p->avl_link[0] == NULL) {
              q = p->avl_link[1];
              if (destroy != NULL && p->avl_data != NULL)
                  destroy(p->avl_data, tree->avl_param);
              tree->avl_alloc->libavl_free(tree->avl_alloc, p);
          } else {
              q = p->avl_link[0];
              p->avl_link[0] = q->avl_link[1];
              q->avl_link[1] = p;
          }
  
      tree->avl_alloc->libavl_free(tree->avl_alloc, tree);
  }
  
  /* Allocates |size| bytes of space using |malloc()|.
   Returns a null poINT_32er if allocation fails. */
  void *
  avl_malloc(struct libavl_allocator *allocator, size_t size) {
      assert (allocator != NULL && size> 0);
      return st_malloc(size);
  }
  
  /* Frees |block|. */
  void avl_free(struct libavl_allocator *allocator, void *block) {
      assert (allocator != NULL && block != NULL);
      free(block);
  }
  
  /* Default memory allocator that uses |malloc()| and |free()|. */
  struct libavl_allocator avl_allocator_default = { avl_malloc, avl_free };
  
  #undef NDEBUG
  #include <assert.h>
  
  /* Asserts that |avl_insert()| succeeds at inserting |item| INT_32o |table|. */
  void( avl_assert_insert)(struct avl_table *table, void *item) {
      void **p = avl_probe(table, item);
      assert (p != NULL && *p == item);
  }
  
  /* Asserts that |avl_delete()| really removes |item| from |table|,
   and returns the removed item. */
  void *
  ( avl_assert_delete)(struct avl_table *table, void *item) {
      void *p = avl_delete(table, item);
      assert (p != NULL);
      return p;
  }
  
  