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/* libavl - manipulates AVL trees.
Copyright (C) 1998, 1999 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 <pfaffben@pilot.msu.edu> on the
Internet, or as Ben Pfaff, 12167 Airport Rd, DeWitt MI 48820, USA
through more mundane means. */
/* This is file avl.h in libavl. */
#if !avl_h
#define avl_h 1
/* The default maximum height of 32 allows for AVL trees having
between 5,704,880 and 4,294,967,295 nodes, depending on order of
insertion. You may change this compile-time constant as you
wish. */
#ifndef AVL_MAX_HEIGHT
#define AVL_MAX_HEIGHT 32
#endif
/* Structure for a node in an AVL tree. */
typedef struct avl_node
{
void *data; /* Pointer to data. */
struct avl_node *link[2]; /* Subtrees. */
signed char bal; /* Balance factor. */
char cache; /* Used during insertion. */
signed char pad[2]; /* Unused. Reserved for threaded trees. */
}
avl_node;
/* Used for traversing an AVL tree. */
typedef struct avl_traverser
{
int init; /* Initialized? */
int nstack; /* Top of stack. */
const avl_node *p; /* Used for traversal. */
const avl_node *stack[AVL_MAX_HEIGHT];/* Descended trees. */
}
avl_traverser;
/* Initializer for avl_traverser. */
#define AVL_TRAVERSER_INIT {0}
/* Function types. */
#if !AVL_FUNC_TYPES
#define AVL_FUNC_TYPES 1
typedef int (*avl_comparison_func) (const void *a, const void *b, void *param);
typedef void (*avl_node_func) (void *data, void *param);
typedef void *(*avl_copy_func) (void *data, void *param);
#endif
/* Structure which holds information about an AVL tree. */
typedef struct avl_tree
{
#if PSPP
struct arena **owner; /* Arena to store nodes. */
#endif
avl_node root; /* Tree root node. */
avl_comparison_func cmp; /* Used to compare keys. */
int count; /* Number of nodes in the tree. */
void *param; /* Arbitary user data. */
}
avl_tree;
#if PSPP
#define MAYBE_ARENA struct arena **owner,
#else
#define MAYBE_ARENA /* nothing */
#endif
/* General functions. */
avl_tree *avl_create (MAYBE_ARENA avl_comparison_func, void *param);
void avl_destroy (avl_tree *, avl_node_func);
void avl_free (avl_tree *);
int avl_count (const avl_tree *);
avl_tree *avl_copy (MAYBE_ARENA const avl_tree *, avl_copy_func);
/* Walk the tree. */
void avl_walk (const avl_tree *, avl_node_func, void *param);
void *avl_traverse (const avl_tree *, avl_traverser *);
#define avl_init_traverser(TRAVERSER) ((TRAVERSER)->init = 0)
/* Search for a given item. */
void **avl_probe (avl_tree *, void *);
void *avl_delete (avl_tree *, const void *);
void *avl_find (const avl_tree *, const void *);
void *avl_find_close (const avl_tree *, const void *);
#if __GCC__ >= 2
extern inline void *
avl_insert (avl_tree *tree, void *item)
{
void **p = avl_probe (tree, item);
return (*p == item) ? NULL : *p;
}
extern inline void *
avl_replace (avl_tree *tree, void *item)
{
void **p = avl_probe (tree, item);
if (*p == item)
return NULL;
else
{
void *r = *p;
*p = item;
return r;
}
}
#else /* not gcc */
void *avl_insert (avl_tree *tree, void *item);
void *avl_replace (avl_tree *tree, void *item);
#endif /* not gcc */
/* Easy assertions on insertion & deletion. */
#ifndef NDEBUG
#define avl_force_insert(A, B) \
do \
{ \
void *r = avl_insert (A, B); \
assert (r == NULL); \
} \
while (0)
void *avl_force_delete (avl_tree *, void *);
#else
#define avl_force_insert(A, B) \
avl_insert (A, B)
#define avl_force_delete(A, B) \
avl_delete (A, B)
#endif
#endif /* avl_h */
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