--- /dev/null
+/* Produced by texiweb from libavl.w. */
+
+/* libavl - library for manipulation of binary trees.
+ Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004 Free Software
+ Foundation, Inc.
+
+ 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 3 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 Street, Fifth Floor, Boston, MA
+ 02110-1301 USA.
+*/
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "avl.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);
+ 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; )
+ {
+ int 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;
+}
+
+/* Inserts |item| into |tree| and returns a pointer to |item|'s address.
+ If a duplicate item is found in the tree,
+ returns a pointer 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. */
+ int dir; /* Direction to descend. */
+
+ unsigned char da[AVL_MAX_HEIGHT]; /* Cached comparison results. */
+ int 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])
+ {
+ int 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| into |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| into |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 pointer 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. */
+ int k; /* Stack pointer. */
+
+ struct avl_node *p; /* Traverses tree to find node to delete. */
+ int 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))
+ {
+ int 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;
+ int 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 pointers 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 pointer 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 pointer 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)
+ {
+ int 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| into |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 pointers to avoid touching uninitialized data. */
+static void
+copy_error_recovery (struct avl_node **stack, int 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 into 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)];
+ int 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 pointer if allocation fails. */
+void *
+avl_malloc (struct libavl_allocator *allocator, size_t size)
+{
+ assert (allocator != NULL && size > 0);
+ return 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| into |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;
+}
+
--- /dev/null
+/* Produced by texiweb from libavl.w. */
+
+/* libavl - library for manipulation of binary trees.
+ Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004 Free Software
+ Foundation, Inc.
+
+ 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 3 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 Street, Fifth Floor, Boston, MA
+ 02110-1301 USA.
+*/
+
+#ifndef AVL_H
+#define AVL_H 1
+
+#include <stddef.h>
+
+/* Function types. */
+typedef int avl_comparison_func (const void *avl_a, const void *avl_b,
+ void *avl_param);
+typedef void avl_item_func (void *avl_item, void *avl_param);
+typedef void *avl_copy_func (void *avl_item, void *avl_param);
+
+#ifndef LIBAVL_ALLOCATOR
+#define LIBAVL_ALLOCATOR
+/* Memory allocator. */
+struct libavl_allocator
+ {
+ void *(*libavl_malloc) (struct libavl_allocator *, size_t libavl_size);
+ void (*libavl_free) (struct libavl_allocator *, void *libavl_block);
+ };
+#endif
+
+/* Default memory allocator. */
+extern struct libavl_allocator avl_allocator_default;
+void *avl_malloc (struct libavl_allocator *, size_t);
+void avl_free (struct libavl_allocator *, void *);
+
+/* Maximum AVL tree height. */
+#ifndef AVL_MAX_HEIGHT
+#define AVL_MAX_HEIGHT 92
+#endif
+
+/* Tree data structure. */
+struct avl_table
+ {
+ struct avl_node *avl_root; /* Tree's root. */
+ avl_comparison_func *avl_compare; /* Comparison function. */
+ void *avl_param; /* Extra argument to |avl_compare|. */
+ struct libavl_allocator *avl_alloc; /* Memory allocator. */
+ size_t avl_count; /* Number of items in tree. */
+ unsigned long avl_generation; /* Generation number. */
+ };
+
+/* An AVL tree node. */
+struct avl_node
+ {
+ struct avl_node *avl_link[2]; /* Subtrees. */
+ void *avl_data; /* Pointer to data. */
+ signed char avl_balance; /* Balance factor. */
+ };
+
+/* AVL traverser structure. */
+struct avl_traverser
+ {
+ struct avl_table *avl_table; /* Tree being traversed. */
+ struct avl_node *avl_node; /* Current node in tree. */
+ struct avl_node *avl_stack[AVL_MAX_HEIGHT];
+ /* All the nodes above |avl_node|. */
+ size_t avl_height; /* Number of nodes in |avl_parent|. */
+ unsigned long avl_generation; /* Generation number. */
+ };
+
+/* Table functions. */
+struct avl_table *avl_create (avl_comparison_func *, void *,
+ struct libavl_allocator *);
+struct avl_table *avl_copy (const struct avl_table *, avl_copy_func *,
+ avl_item_func *, struct libavl_allocator *);
+void avl_destroy (struct avl_table *, avl_item_func *);
+void **avl_probe (struct avl_table *, void *);
+void *avl_insert (struct avl_table *, void *);
+void *avl_replace (struct avl_table *, void *);
+void *avl_delete (struct avl_table *, const void *);
+void *avl_find (const struct avl_table *, const void *);
+void avl_assert_insert (struct avl_table *, void *);
+void *avl_assert_delete (struct avl_table *, void *);
+
+#define avl_count(table) ((size_t) (table)->avl_count)
+
+/* Table traverser functions. */
+void avl_t_init (struct avl_traverser *, struct avl_table *);
+void *avl_t_first (struct avl_traverser *, struct avl_table *);
+void *avl_t_last (struct avl_traverser *, struct avl_table *);
+void *avl_t_find (struct avl_traverser *, struct avl_table *, void *);
+void *avl_t_insert (struct avl_traverser *, struct avl_table *, void *);
+void *avl_t_copy (struct avl_traverser *, const struct avl_traverser *);
+void *avl_t_next (struct avl_traverser *);
+void *avl_t_prev (struct avl_traverser *);
+void *avl_t_cur (struct avl_traverser *);
+void *avl_t_replace (struct avl_traverser *, void *);
+
+#endif /* avl.h */
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