自平衡二叉查找树(二）-----------红黑树(redblack tree)分析和代码实现

资源下载:源代码及原理解释

/* 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.
*/

#ifndef RB_H
#define RB_H 1

#include <stddef.h>

/* Function types. */
typedef int rb_comparison_func (const void *rb_a, const void *rb_b,
void *rb_param);
typedef void rb_item_func (void *rb_item, void *rb_param);
typedef void *rb_copy_func (void *rb_item, void *rb_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 rb_allocator_default;
void *rb_malloc (struct libavl_allocator *, size_t);
void rb_free (struct libavl_allocator *, void *);

/* Maximum RB height. */
#ifndef RB_MAX_HEIGHT
#define RB_MAX_HEIGHT 48
#endif

/* Tree data structure. */
struct rb_table
{
struct rb_node *rb_root;          /* Tree's root. */
rb_comparison_func *rb_compare;   /* Comparison function. */
void *rb_param;                    /* Extra argument to |rb_compare|. */
struct libavl_allocator *rb_alloc; /* Memory allocator. */
size_t rb_count;                   /* Number of items in tree. */
unsigned long rb_generation;       /* Generation number. */
};

/* Color of a red-black node. */
enum rb_color
{
RB_BLACK,   /* Black. */
RB_RED      /* Red. */
};

/* A red-black tree node. */
struct rb_node
{
struct rb_node *rb_link[2];   /* Subtrees. */
void *rb_data;                /* Pointer to data. */
unsigned char rb_color;       /* Color. */
};

/* RB traverser structure. */
struct rb_traverser
{
struct rb_table *rb_table;        /* Tree being traversed. */
struct rb_node *rb_node;          /* Current node in tree. */
struct rb_node *rb_stack[RB_MAX_HEIGHT];
/* All the nodes above |rb_node|. */
size_t rb_height;                  /* Number of nodes in |rb_parent|. */
unsigned long rb_generation;       /* Generation number. */
};

/* Table functions. */
struct rb_table *rb_create (rb_comparison_func *, void *,
struct libavl_allocator *);
struct rb_table *rb_copy (const struct rb_table *, rb_copy_func *,
rb_item_func *, struct libavl_allocator *);
void rb_destroy (struct rb_table *, rb_item_func *);
void **rb_probe (struct rb_table *, void *);
void *rb_insert (struct rb_table *, void *);
void *rb_replace (struct rb_table *, void *);
void *rb_delete (struct rb_table *, const void *);
void *rb_find (const struct rb_table *, const void *);
void rb_assert_insert (struct rb_table *, void *);
void *rb_assert_delete (struct rb_table *, void *);

#define rb_count(table) ((size_t) (table)->rb_count)

/* Table traverser functions. */
void rb_t_init (struct rb_traverser *, struct rb_table *);
void *rb_t_first (struct rb_traverser *, struct rb_table *);
void *rb_t_last (struct rb_traverser *, struct rb_table *);
void *rb_t_find (struct rb_traverser *, struct rb_table *, void *);
void *rb_t_insert (struct rb_traverser *, struct rb_table *, void *);
void *rb_t_copy (struct rb_traverser *, const struct rb_traverser *);
void *rb_t_next (struct rb_traverser *);
void *rb_t_prev (struct rb_traverser *);
void *rb_t_cur (struct rb_traverser *);
void *rb_t_replace (struct rb_traverser *, void *);

#endif /* rb.h */

/* 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 "rb.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 rb_table *
rb_create (rb_comparison_func *compare, void *param,
struct libavl_allocator *allocator)
{
struct rb_table *tree;

assert (compare != NULL);

if (allocator == NULL)
allocator = &rb_allocator_default;

tree = allocator->libavl_malloc (allocator, sizeof *tree);
if (tree == NULL)
return NULL;

tree->rb_root = NULL;
tree->rb_compare = compare;
tree->rb_param = param;
tree->rb_alloc = allocator;
tree->rb_count = 0;
tree->rb_generation = 0;

return tree;
}

/* Search |tree| for an item matching |item|, and return it if found.
Otherwise return |NULL|. */
void *
rb_find (const struct rb_table *tree, const void *item)
{
const struct rb_node *p;

assert (tree != NULL && item != NULL);
for (p = tree->rb_root; p != NULL; )
{
int cmp = tree->rb_compare (item, p->rb_data, tree->rb_param);

if (cmp < 0)
p = p->rb_link[0];
else if (cmp > 0)
p = p->rb_link[1];
else /* |cmp == 0| */
return p->rb_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 **
rb_probe (struct rb_table *tree, void *item)
{
struct rb_node *pa[RB_MAX_HEIGHT]; /* Nodes on stack. */
unsigned char da[RB_MAX_HEIGHT];   /* Directions moved from stack nodes. */
int k;                             /* Stack height. */

struct rb_node *p; /* Traverses tree looking for insertion point. */
struct rb_node *n; /* Newly inserted node. */

assert (tree != NULL && item != NULL);

pa[0] = (struct rb_node *) &tree->rb_root;
da[0] = 0;
k = 1;
for (p = tree->rb_root; p != NULL; p = p->rb_link[da[k - 1]])
{
int cmp = tree->rb_compare (item, p->rb_data, tree->rb_param);
if (cmp == 0)
return &p->rb_data;

pa[k] = p;
da[k++] = cmp > 0;
}

n = pa[k - 1]->rb_link[da[k - 1]] =
tree->rb_alloc->libavl_malloc (tree->rb_alloc, sizeof *n);
if (n == NULL)
return NULL;

n->rb_data = item;
n->rb_link[0] = n->rb_link[1] = NULL;
n->rb_color = RB_RED;
tree->rb_count++;
tree->rb_generation++;

while (k >= 3 && pa[k - 1]->rb_color == RB_RED)
{
if (da[k - 2] == 0)
{
struct rb_node *y = pa[k - 2]->rb_link[1];
if (y != NULL && y->rb_color == RB_RED)
{
pa[k - 1]->rb_color = y->rb_color = RB_BLACK;
pa[k - 2]->rb_color = RB_RED;
k -= 2;
}
else
{
struct rb_node *x;

if (da[k - 1] == 0)
y = pa[k - 1];
else
{
x = pa[k - 1];
y = x->rb_link[1];
x->rb_link[1] = y->rb_link[0];
y->rb_link[0] = x;
pa[k - 2]->rb_link[0] = y;
}

x = pa[k - 2];
x->rb_color = RB_RED;
y->rb_color = RB_BLACK;

x->rb_link[0] = y->rb_link[1];
y->rb_link[1] = x;
pa[k - 3]->rb_link[da[k - 3]] = y;
break;
}
}
else
{
struct rb_node *y = pa[k - 2]->rb_link[0];
if (y != NULL && y->rb_color == RB_RED)
{
pa[k - 1]->rb_color = y->rb_color = RB_BLACK;
pa[k - 2]->rb_color = RB_RED;
k -= 2;
}
else
{
struct rb_node *x;

if (da[k - 1] == 1)
y = pa[k - 1];
else
{
x = pa[k - 1];
y = x->rb_link[0];
x->rb_link[0] = y->rb_link[1];
y->rb_link[1] = x;
pa[k - 2]->rb_link[1] = y;
}

x = pa[k - 2];
x->rb_color = RB_RED;
y->rb_color = RB_BLACK;

x->rb_link[1] = y->rb_link[0];
y->rb_link[0] = x;
pa[k - 3]->rb_link[da[k - 3]] = y;
break;
}
}
}
tree->rb_root->rb_color = RB_BLACK;

return &n->rb_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 *
rb_insert (struct rb_table *table, void *item)
{
void **p = rb_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 *
rb_replace (struct rb_table *table, void *item)
{
void **p = rb_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 *
rb_delete (struct rb_table *tree, const void *item)
{
struct rb_node *pa[RB_MAX_HEIGHT]; /* Nodes on stack. */
unsigned char da[RB_MAX_HEIGHT];   /* Directions moved from stack nodes. */
int k;                             /* Stack height. */

struct rb_node *p;    /* The node to delete, or a node part way to it. */
int cmp;              /* Result of comparison between |item| and |p|. */

assert (tree != NULL && item != NULL);

k = 0;
p = (struct rb_node *) &tree->rb_root;
for (cmp = -1; cmp != 0;
cmp = tree->rb_compare (item, p->rb_data, tree->rb_param))
{
int dir = cmp > 0;

pa[k] = p;
da[k++] = dir;

p = p->rb_link[dir];
if (p == NULL)
return NULL;
}
item = p->rb_data;

if (p->rb_link[1] == NULL)
pa[k - 1]->rb_link[da[k - 1]] = p->rb_link[0];
else
{
enum rb_color t;
struct rb_node *r = p->rb_link[1];

if (r->rb_link[0] == NULL)
{
r->rb_link[0] = p->rb_link[0];
t = r->rb_color;
r->rb_color = p->rb_color;
p->rb_color = t;
pa[k - 1]->rb_link[da[k - 1]] = r;
da[k] = 1;
pa[k++] = r;
}
else
{
struct rb_node *s;
int j = k++;

for (;;)
{
da[k] = 0;
pa[k++] = r;
s = r->rb_link[0];
if (s->rb_link[0] == NULL)
break;

r = s;
}

da[j] = 1;
pa[j] = s;
pa[j - 1]->rb_link[da[j - 1]] = s;

s->rb_link[0] = p->rb_link[0];
r->rb_link[0] = s->rb_link[1];
s->rb_link[1] = p->rb_link[1];

t = s->rb_color;
s->rb_color = p->rb_color;
p->rb_color = t;
}
}

if (p->rb_color == RB_BLACK)
{
for (;;)
{
struct rb_node *x = pa[k - 1]->rb_link[da[k - 1]];
if (x != NULL && x->rb_color == RB_RED)
{
x->rb_color = RB_BLACK;
break;
}
if (k < 2)
break;

if (da[k - 1] == 0)
{
struct rb_node *w = pa[k - 1]->rb_link[1];

if (w->rb_color == RB_RED)
{
w->rb_color = RB_BLACK;
pa[k - 1]->rb_color = RB_RED;

pa[k - 1]->rb_link[1] = w->rb_link[0];
w->rb_link[0] = pa[k - 1];
pa[k - 2]->rb_link[da[k - 2]] = w;

pa[k] = pa[k - 1];
da[k] = 0;
pa[k - 1] = w;
k++;

w = pa[k - 1]->rb_link[1];
}

if ((w->rb_link[0] == NULL
|| w->rb_link[0]->rb_color == RB_BLACK)
&& (w->rb_link[1] == NULL
|| w->rb_link[1]->rb_color == RB_BLACK))
w->rb_color = RB_RED;
else
{
if (w->rb_link[1] == NULL
|| w->rb_link[1]->rb_color == RB_BLACK)
{
struct rb_node *y = w->rb_link[0];
y->rb_color = RB_BLACK;
w->rb_color = RB_RED;
w->rb_link[0] = y->rb_link[1];
y->rb_link[1] = w;
w = pa[k - 1]->rb_link[1] = y;
}

w->rb_color = pa[k - 1]->rb_color;
pa[k - 1]->rb_color = RB_BLACK;
w->rb_link[1]->rb_color = RB_BLACK;

pa[k - 1]->rb_link[1] = w->rb_link[0];
w->rb_link[0] = pa[k - 1];
pa[k - 2]->rb_link[da[k - 2]] = w;
break;
}
}
else
{
struct rb_node *w = pa[k - 1]->rb_link[0];

if (w->rb_color == RB_RED)
{
w->rb_color = RB_BLACK;
pa[k - 1]->rb_color = RB_RED;

pa[k - 1]->rb_link[0] = w->rb_link[1];
w->rb_link[1] = pa[k - 1];
pa[k - 2]->rb_link[da[k - 2]] = w;

pa[k] = pa[k - 1];
da[k] = 1;
pa[k - 1] = w;
k++;

w = pa[k - 1]->rb_link[0];
}

if ((w->rb_link[0] == NULL
|| w->rb_link[0]->rb_color == RB_BLACK)
&& (w->rb_link[1] == NULL
|| w->rb_link[1]->rb_color == RB_BLACK))
w->rb_color = RB_RED;
else
{
if (w->rb_link[0] == NULL
|| w->rb_link[0]->rb_color == RB_BLACK)
{
struct rb_node *y = w->rb_link[1];
y->rb_color = RB_BLACK;
w->rb_color = RB_RED;
w->rb_link[1] = y->rb_link[0];
y->rb_link[0] = w;
w = pa[k - 1]->rb_link[0] = y;
}

w->rb_color = pa[k - 1]->rb_color;
pa[k - 1]->rb_color = RB_BLACK;
w->rb_link[0]->rb_color = RB_BLACK;

pa[k - 1]->rb_link[0] = w->rb_link[1];
w->rb_link[1] = pa[k - 1];
pa[k - 2]->rb_link[da[k - 2]] = w;
break;
}
}

k--;
}

}

tree->rb_alloc->libavl_free (tree->rb_alloc, p);
tree->rb_count--;
tree->rb_generation++;
return (void *) item;
}

/* Refreshes the stack of parent pointers in |trav|
and updates its generation number. */
static void
trav_refresh (struct rb_traverser *trav)
{
assert (trav != NULL);

trav->rb_generation = trav->rb_table->rb_generation;

if (trav->rb_node != NULL)
{
rb_comparison_func *cmp = trav->rb_table->rb_compare;
void *param = trav->rb_table->rb_param;
struct rb_node *node = trav->rb_node;
struct rb_node *i;

trav->rb_height = 0;
for (i = trav->rb_table->rb_root; i != node; )
{
assert (trav->rb_height < RB_MAX_HEIGHT);
assert (i != NULL);

trav->rb_stack[trav->rb_height++] = i;
i = i->rb_link[cmp (node->rb_data, i->rb_data, param) > 0];
}
}
}

/* Initializes |trav| for use with |tree|
and selects the null node. */
void
rb_t_init (struct rb_traverser *trav, struct rb_table *tree)
{
trav->rb_table = tree;
trav->rb_node = NULL;
trav->rb_height = 0;
trav->rb_generation = tree->rb_generation;
}

/* Initializes |trav| for |tree|
and selects and returns a pointer to its least-valued item.
Returns |NULL| if |tree| contains no nodes. */
void *
rb_t_first (struct rb_traverser *trav, struct rb_table *tree)
{
struct rb_node *x;

assert (tree != NULL && trav != NULL);

trav->rb_table = tree;
trav->rb_height = 0;
trav->rb_generation = tree->rb_generation;

x = tree->rb_root;
if (x != NULL)
while (x->rb_link[0] != NULL)
{
assert (trav->rb_height < RB_MAX_HEIGHT);
trav->rb_stack[trav->rb_height++] = x;
x = x->rb_link[0];
}
trav->rb_node = x;

return x != NULL ? x->rb_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 *
rb_t_last (struct rb_traverser *trav, struct rb_table *tree)
{
struct rb_node *x;

assert (tree != NULL && trav != NULL);

trav->rb_table = tree;
trav->rb_height = 0;
trav->rb_generation = tree->rb_generation;

x = tree->rb_root;
if (x != NULL)
while (x->rb_link[1] != NULL)
{
assert (trav->rb_height < RB_MAX_HEIGHT);
trav->rb_stack[trav->rb_height++] = x;
x = x->rb_link[1];
}
trav->rb_node = x;

return x != NULL ? x->rb_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 *
rb_t_find (struct rb_traverser *trav, struct rb_table *tree, void *item)
{
struct rb_node *p, *q;

assert (trav != NULL && tree != NULL && item != NULL);
trav->rb_table = tree;
trav->rb_height = 0;
trav->rb_generation = tree->rb_generation;
for (p = tree->rb_root; p != NULL; p = q)
{
int cmp = tree->rb_compare (item, p->rb_data, tree->rb_param);

if (cmp < 0)
q = p->rb_link[0];
else if (cmp > 0)
q = p->rb_link[1];
else /* |cmp == 0| */
{
trav->rb_node = p;
return p->rb_data;
}

assert (trav->rb_height < RB_MAX_HEIGHT);
trav->rb_stack[trav->rb_height++] = p;
}

trav->rb_height = 0;
trav->rb_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 *
rb_t_insert (struct rb_traverser *trav, struct rb_table *tree, void *item)
{
void **p;

assert (trav != NULL && tree != NULL && item != NULL);

p = rb_probe (tree, item);
if (p != NULL)
{
trav->rb_table = tree;
trav->rb_node =
((struct rb_node *)
((char *) p - offsetof (struct rb_node, rb_data)));
trav->rb_generation = tree->rb_generation - 1;
return *p;
}
else
{
rb_t_init (trav, tree);
return NULL;
}
}

/* Initializes |trav| to have the same current node as |src|. */
void *
rb_t_copy (struct rb_traverser *trav, const struct rb_traverser *src)
{
assert (trav != NULL && src != NULL);

if (trav != src)
{
trav->rb_table = src->rb_table;
trav->rb_node = src->rb_node;
trav->rb_generation = src->rb_generation;
if (trav->rb_generation == trav->rb_table->rb_generation)
{
trav->rb_height = src->rb_height;
memcpy (trav->rb_stack, (const void *) src->rb_stack,
sizeof *trav->rb_stack * trav->rb_height);
}
}

return trav->rb_node != NULL ? trav->rb_node->rb_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 *
rb_t_next (struct rb_traverser *trav)
{
struct rb_node *x;

assert (trav != NULL);

if (trav->rb_generation != trav->rb_table->rb_generation)
trav_refresh (trav);

x = trav->rb_node;
if (x == NULL)
{
return rb_t_first (trav, trav->rb_table);
}
else if (x->rb_link[1] != NULL)
{
assert (trav->rb_height < RB_MAX_HEIGHT);
trav->rb_stack[trav->rb_height++] = x;
x = x->rb_link[1];

while (x->rb_link[0] != NULL)
{
assert (trav->rb_height < RB_MAX_HEIGHT);
trav->rb_stack[trav->rb_height++] = x;
x = x->rb_link[0];
}
}
else
{
struct rb_node *y;

do
{
if (trav->rb_height == 0)
{
trav->rb_node = NULL;
return NULL;
}

y = x;
x = trav->rb_stack[--trav->rb_height];
}
while (y == x->rb_link[1]);
}
trav->rb_node = x;

return x->rb_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 *
rb_t_prev (struct rb_traverser *trav)
{
struct rb_node *x;

assert (trav != NULL);

if (trav->rb_generation != trav->rb_table->rb_generation)
trav_refresh (trav);

x = trav->rb_node;
if (x == NULL)
{
return rb_t_last (trav, trav->rb_table);
}
else if (x->rb_link[0] != NULL)
{
assert (trav->rb_height < RB_MAX_HEIGHT);
trav->rb_stack[trav->rb_height++] = x;
x = x->rb_link[0];

while (x->rb_link[1] != NULL)
{
assert (trav->rb_height < RB_MAX_HEIGHT);
trav->rb_stack[trav->rb_height++] = x;
x = x->rb_link[1];
}
}
else
{
struct rb_node *y;

do
{
if (trav->rb_height == 0)
{
trav->rb_node = NULL;
return NULL;
}

y = x;
x = trav->rb_stack[--trav->rb_height];
}
while (y == x->rb_link[0]);
}
trav->rb_node = x;

return x->rb_data;
}

/* Returns |trav|'s current item. */
void *
rb_t_cur (struct rb_traverser *trav)
{
assert (trav != NULL);

return trav->rb_node != NULL ? trav->rb_node->rb_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 *
rb_t_replace (struct rb_traverser *trav, void *new)
{
void *old;

assert (trav != NULL && trav->rb_node != NULL && new != NULL);
old = trav->rb_node->rb_data;
trav->rb_node->rb_data = new;
return old;
}

/* Destroys |new| with |rb_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 rb_node **stack, int height,
struct rb_table *new, rb_item_func *destroy)
{
assert (stack != NULL && height >= 0 && new != NULL);

for (; height > 2; height -= 2)
stack[height - 1]->rb_link[1] = NULL;
rb_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 rb_table *
rb_copy (const struct rb_table *org, rb_copy_func *copy,
rb_item_func *destroy, struct libavl_allocator *allocator)
{
struct rb_node *stack[2 * (RB_MAX_HEIGHT + 1)];
int height = 0;

struct rb_table *new;
const struct rb_node *x;
struct rb_node *y;

assert (org != NULL);
new = rb_create (org->rb_compare, org->rb_param,
allocator != NULL ? allocator : org->rb_alloc);
if (new == NULL)
return NULL;
new->rb_count = org->rb_count;
if (new->rb_count == 0)
return new;

x = (const struct rb_node *) &org->rb_root;
y = (struct rb_node *) &new->rb_root;
for (;;)
{
while (x->rb_link[0] != NULL)
{
assert (height < 2 * (RB_MAX_HEIGHT + 1));

y->rb_link[0] =
new->rb_alloc->libavl_malloc (new->rb_alloc,
sizeof *y->rb_link[0]);
if (y->rb_link[0] == NULL)
{
if (y != (struct rb_node *) &new->rb_root)
{
y->rb_data = NULL;
y->rb_link[1] = NULL;
}

copy_error_recovery (stack, height, new, destroy);
return NULL;
}

stack[height++] = (struct rb_node *) x;
stack[height++] = y;
x = x->rb_link[0];
y = y->rb_link[0];
}
y->rb_link[0] = NULL;

for (;;)
{
y->rb_color = x->rb_color;
if (copy == NULL)
y->rb_data = x->rb_data;
else
{
y->rb_data = copy (x->rb_data, org->rb_param);
if (y->rb_data == NULL)
{
y->rb_link[1] = NULL;
copy_error_recovery (stack, height, new, destroy);
return NULL;
}
}

if (x->rb_link[1] != NULL)
{
y->rb_link[1] =
new->rb_alloc->libavl_malloc (new->rb_alloc,
sizeof *y->rb_link[1]);
if (y->rb_link[1] == NULL)
{
copy_error_recovery (stack, height, new, destroy);
return NULL;
}

x = x->rb_link[1];
y = y->rb_link[1];
break;
}
else
y->rb_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
rb_destroy (struct rb_table *tree, rb_item_func *destroy)
{
struct rb_node *p, *q;

assert (tree != NULL);

for (p = tree->rb_root; p != NULL; p = q)
if (p->rb_link[0] == NULL)
{
q = p->rb_link[1];
if (destroy != NULL && p->rb_data != NULL)
destroy (p->rb_data, tree->rb_param);
tree->rb_alloc->libavl_free (tree->rb_alloc, p);
}
else
{
q = p->rb_link[0];
p->rb_link[0] = q->rb_link[1];
q->rb_link[1] = p;
}

tree->rb_alloc->libavl_free (tree->rb_alloc, tree);
}

/* Allocates |size| bytes of space using |malloc()|.
Returns a null pointer if allocation fails. */
void *
rb_malloc (struct libavl_allocator *allocator, size_t size)
{
assert (allocator != NULL && size > 0);
return malloc (size);
}

/* Frees |block|. */
void
rb_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 rb_allocator_default =
{
rb_malloc,
rb_free
};

#undef NDEBUG
#include <assert.h>

/* Asserts that |rb_insert()| succeeds at inserting |item| into |table|. */
void
(rb_assert_insert) (struct rb_table *table, void *item)
{
void **p = rb_probe (table, item);
assert (p != NULL && *p == item);
}

/* Asserts that |rb_delete()| really removes |item| from |table|,
and returns the removed item. */
void *
(rb_assert_delete) (struct rb_table *table, void *item)
{
void *p = rb_delete (table, item);
assert (p != NULL);
return p;
}