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220 lines
9.2 KiB
C
220 lines
9.2 KiB
C
/* tree.h -- AVL trees (in the spirit of BSD's 'queue.h') -*- C -*- */
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/* Copyright (c) 2005 Ian Piumarta
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*
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the 'Software'), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, and/or sell copies of the
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* Software, and to permit persons to whom the Software is furnished to do so,
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* provided that the above copyright notice(s) and this permission notice appear
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* in all copies of the Software and that both the above copyright notice(s) and
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* this permission notice appear in supporting documentation.
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*
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* THE SOFTWARE IS PROVIDED 'AS IS'. USE ENTIRELY AT YOUR OWN RISK.
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*/
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/* This file defines an AVL balanced binary tree [Georgii M. Adelson-Velskii and
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* Evgenii M. Landis, 'An algorithm for the organization of information',
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* Doklady Akademii Nauk SSSR, 146:263-266, 1962 (Russian). Also in Myron
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* J. Ricci (trans.), Soviet Math, 3:1259-1263, 1962 (English)].
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*
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* An AVL tree is headed by pointers to the root node and to a function defining
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* the ordering relation between nodes. Each node contains an arbitrary payload
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* plus three fields per tree entry: the depth of the subtree for which it forms
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* the root and two pointers to child nodes (singly-linked for minimum space, at
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* the expense of direct access to the parent node given a pointer to one of the
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* children). The tree is rebalanced after every insertion or removal. The
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* tree may be traversed in two directions: forward (in-order left-to-right) and
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* reverse (in-order, right-to-left).
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*
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* Because of the recursive nature of many of the operations on trees it is
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* necessary to define a number of helper functions for each type of tree node.
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* The macro TREE_DEFINE(node_tag, entry_name) defines these functions with
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* unique names according to the node_tag. This macro should be invoked,
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* thereby defining the necessary functions, once per node tag in the program.
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*
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* For details on the use of these macros, see the tree(3) manual page.
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*/
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#ifndef __tree_h
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#define __tree_h
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#define TREE_DELTA_MAX 1
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#ifndef _HU_FUNCTION
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# if defined(__GNUC__) || defined(__clang__)
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# define _HU_FUNCTION(x) __attribute__((__unused__)) x
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# else
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# define _HU_FUNCTION(x) x
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# endif
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#endif
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#define TREE_ENTRY(type) \
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struct { \
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struct type *avl_left; \
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struct type *avl_right; \
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int avl_height; \
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}
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#define TREE_HEAD(name, type) \
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struct name { \
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struct type *th_root; \
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int (*th_cmp)(struct type *lhs, struct type *rhs); \
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}
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#define TREE_INITIALIZER(cmp) { 0, cmp }
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#define TREE_DELTA(self, field) \
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(( (((self)->field.avl_left) ? (self)->field.avl_left->field.avl_height : 0)) \
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- (((self)->field.avl_right) ? (self)->field.avl_right->field.avl_height : 0))
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/* Recursion prevents the following from being defined as macros. */
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#define TREE_DEFINE(node, field) \
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\
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static struct node *_HU_FUNCTION(TREE_BALANCE_##node##_##field)(struct node *); \
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\
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static struct node *_HU_FUNCTION(TREE_ROTL_##node##_##field)(struct node *self) \
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{ \
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struct node *r= self->field.avl_right; \
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self->field.avl_right= r->field.avl_left; \
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r->field.avl_left= TREE_BALANCE_##node##_##field(self); \
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return TREE_BALANCE_##node##_##field(r); \
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} \
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\
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static struct node *_HU_FUNCTION(TREE_ROTR_##node##_##field)(struct node *self) \
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{ \
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struct node *l= self->field.avl_left; \
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self->field.avl_left= l->field.avl_right; \
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l->field.avl_right= TREE_BALANCE_##node##_##field(self); \
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return TREE_BALANCE_##node##_##field(l); \
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} \
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\
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static struct node *_HU_FUNCTION(TREE_BALANCE_##node##_##field)(struct node *self) \
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{ \
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int delta= TREE_DELTA(self, field); \
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\
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if (delta < -TREE_DELTA_MAX) \
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{ \
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if (TREE_DELTA(self->field.avl_right, field) > 0) \
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self->field.avl_right= TREE_ROTR_##node##_##field(self->field.avl_right); \
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return TREE_ROTL_##node##_##field(self); \
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} \
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else if (delta > TREE_DELTA_MAX) \
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{ \
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if (TREE_DELTA(self->field.avl_left, field) < 0) \
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self->field.avl_left= TREE_ROTL_##node##_##field(self->field.avl_left); \
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return TREE_ROTR_##node##_##field(self); \
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} \
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self->field.avl_height= 0; \
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if (self->field.avl_left && (self->field.avl_left->field.avl_height > self->field.avl_height)) \
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self->field.avl_height= self->field.avl_left->field.avl_height; \
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if (self->field.avl_right && (self->field.avl_right->field.avl_height > self->field.avl_height)) \
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self->field.avl_height= self->field.avl_right->field.avl_height; \
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self->field.avl_height += 1; \
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return self; \
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} \
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\
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static struct node *_HU_FUNCTION(TREE_INSERT_##node##_##field) \
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(struct node *self, struct node *elm, int (*compare)(struct node *lhs, struct node *rhs)) \
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{ \
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if (!self) \
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return elm; \
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if (compare(elm, self) < 0) \
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self->field.avl_left= TREE_INSERT_##node##_##field(self->field.avl_left, elm, compare); \
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else \
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self->field.avl_right= TREE_INSERT_##node##_##field(self->field.avl_right, elm, compare); \
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return TREE_BALANCE_##node##_##field(self); \
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} \
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\
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static struct node *_HU_FUNCTION(TREE_FIND_##node##_##field) \
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(struct node *self, struct node *elm, int (*compare)(struct node *lhs, struct node *rhs)) \
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{ \
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if (!self) \
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return 0; \
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if (compare(elm, self) == 0) \
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return self; \
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if (compare(elm, self) < 0) \
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return TREE_FIND_##node##_##field(self->field.avl_left, elm, compare); \
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else \
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return TREE_FIND_##node##_##field(self->field.avl_right, elm, compare); \
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} \
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\
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static struct node *_HU_FUNCTION(TREE_MOVE_RIGHT)(struct node *self, struct node *rhs) \
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{ \
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if (!self) \
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return rhs; \
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self->field.avl_right= TREE_MOVE_RIGHT(self->field.avl_right, rhs); \
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return TREE_BALANCE_##node##_##field(self); \
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} \
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\
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static struct node *_HU_FUNCTION(TREE_REMOVE_##node##_##field) \
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(struct node *self, struct node *elm, int (*compare)(struct node *lhs, struct node *rhs)) \
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{ \
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if (!self) return 0; \
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\
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if (compare(elm, self) == 0) \
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{ \
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struct node *tmp= TREE_MOVE_RIGHT(self->field.avl_left, self->field.avl_right); \
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self->field.avl_left= 0; \
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self->field.avl_right= 0; \
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return tmp; \
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} \
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if (compare(elm, self) < 0) \
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self->field.avl_left= TREE_REMOVE_##node##_##field(self->field.avl_left, elm, compare); \
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else \
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self->field.avl_right= TREE_REMOVE_##node##_##field(self->field.avl_right, elm, compare); \
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return TREE_BALANCE_##node##_##field(self); \
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} \
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\
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static void _HU_FUNCTION(TREE_FORWARD_APPLY_ALL_##node##_##field) \
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(struct node *self, void (*function)(struct node *node, void *data), void *data) \
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{ \
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if (self) \
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{ \
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TREE_FORWARD_APPLY_ALL_##node##_##field(self->field.avl_left, function, data); \
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function(self, data); \
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TREE_FORWARD_APPLY_ALL_##node##_##field(self->field.avl_right, function, data); \
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} \
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} \
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\
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static void _HU_FUNCTION(TREE_REVERSE_APPLY_ALL_##node##_##field) \
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(struct node *self, void (*function)(struct node *node, void *data), void *data) \
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{ \
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if (self) \
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{ \
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TREE_REVERSE_APPLY_ALL_##node##_##field(self->field.avl_right, function, data); \
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function(self, data); \
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TREE_REVERSE_APPLY_ALL_##node##_##field(self->field.avl_left, function, data); \
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} \
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}
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#define TREE_INSERT(head, node, field, elm) \
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((head)->th_root= TREE_INSERT_##node##_##field((head)->th_root, (elm), (head)->th_cmp))
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#define TREE_FIND(head, node, field, elm) \
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(TREE_FIND_##node##_##field((head)->th_root, (elm), (head)->th_cmp))
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#define TREE_REMOVE(head, node, field, elm) \
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((head)->th_root= TREE_REMOVE_##node##_##field((head)->th_root, (elm), (head)->th_cmp))
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#define TREE_DEPTH(head, field) \
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((head)->th_root->field.avl_height)
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#define TREE_FORWARD_APPLY(head, node, field, function, data) \
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TREE_FORWARD_APPLY_ALL_##node##_##field((head)->th_root, function, data)
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#define TREE_REVERSE_APPLY(head, node, field, function, data) \
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TREE_REVERSE_APPLY_ALL_##node##_##field((head)->th_root, function, data)
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#define TREE_INIT(head, cmp) do { \
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(head)->th_root= 0; \
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(head)->th_cmp= (cmp); \
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} while (0)
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#endif /* __tree_h */
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