476 lines
19 KiB
C
476 lines
19 KiB
C
/*
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The Clear BSD License
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Copyright (c) 2023 Max Wash
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted (subject to the limitations in the disclaimer
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below) provided that the following conditions are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of the copyright holder nor the names of its
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contributors may be used to endorse or promote products derived from this
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software without specific prior written permission.
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*/
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#ifndef KERNEL_BTREE_H_
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#define KERNEL_BTREE_H_
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* if your custom structure contains a struct btree_node (i.e. it can be part of
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a btree), you can use this macro to convert a struct btree_node* to a
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your_type*
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@param t the name of your custom type (something that can be passed to
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offsetof)
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@param m the name of the struct btree_node member variable within your custom
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type.
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@param v the struct btree_node pointer that you wish to convert. if this is
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NULL, NULL will be returned.
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*/
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#define BTREE_CONTAINER(t, m, v) \
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((void *)((v) ? (uintptr_t)(v) - (offsetof(t, m)) : 0))
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/* defines a simple node insertion function.
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this function assumes that your nodes have simple integer keys that can be
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compared with the usual operators.
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EXAMPLE:
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if you have a tree node type like this:
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struct my_tree_node {
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int key;
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struct btree_node base;
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}
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You would use the following call to generate an insert function for a tree
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with this node type:
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BTREE_DEFINE_SIMPLE_INSERT(struct my_tree_node, base, key,
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my_tree_node_insert);
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Which would emit a function defined like:
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static void my_tree_node_insert(struct btree *tree, struct my_tree_node
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*node);
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@param node_type your custom tree node type. usually a structure that
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contains a struct btree_node member.
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@param container_node_member the name of the struct btree_node member
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variable within your custom type.
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@param container_key_member the name of the key member variable within your
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custom type.
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@param function_name the name of the function to generate.
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*/
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#define BTREE_DEFINE_SIMPLE_INSERT( \
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node_type, \
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container_node_member, \
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container_key_member, \
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function_name) \
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void function_name(struct btree *tree, node_type *node) \
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{ \
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if (!tree->b_root) { \
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tree->b_root = &node->container_node_member; \
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btree_insert_fixup( \
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tree, \
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&node->container_node_member); \
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return; \
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} \
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\
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struct btree_node *cur = tree->b_root; \
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while (1) { \
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node_type *cur_node = BTREE_CONTAINER( \
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node_type, \
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container_node_member, \
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cur); \
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struct btree_node *next = NULL; \
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\
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if (node->container_key_member \
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> cur_node->container_key_member) { \
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next = btree_right(cur); \
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\
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if (!next) { \
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btree_put_right( \
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cur, \
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&node->container_node_member); \
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break; \
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} \
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} else if ( \
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node->container_key_member \
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< cur_node->container_key_member) { \
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next = btree_left(cur); \
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\
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if (!next) { \
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btree_put_left( \
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cur, \
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&node->container_node_member); \
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break; \
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} \
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} else { \
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return; \
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} \
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\
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cur = next; \
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} \
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\
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btree_insert_fixup(tree, &node->container_node_member); \
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}
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/* defines a node insertion function.
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this function should be used for trees with complex node keys that cannot be
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directly compared. a comparator for your keys must be supplied.
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EXAMPLE:
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if you have a tree node type like this:
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struct my_tree_node {
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complex_key_t key;
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struct btree_node base;
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}
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You would need to define a comparator function or macro with the following
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signature:
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int my_comparator(struct my_tree_node *a, struct my_tree_node *b);
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Which implements the following:
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return -1 if a < b
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return 0 if a == b
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return 1 if a > b
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You would use the following call to generate an insert function for a tree
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with this node type:
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BTREE_DEFINE_INSERT(struct my_tree_node, base, key, my_tree_node_insert,
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my_comparator);
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Which would emit a function defined like:
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static void my_tree_node_insert(struct btree *tree, struct my_tree_node
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*node);
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@param node_type your custom tree node type. usually a structure that
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contains a struct btree_node member.
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@param container_node_member the name of the struct btree_node member
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variable within your custom type.
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@param container_key_member the name of the key member variable within your
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custom type.
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@param function_name the name of the function to generate.
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@param comparator the name of a comparator function or functional-macro that
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conforms to the requirements listed above.
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*/
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#define BTREE_DEFINE_INSERT( \
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node_type, \
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container_node_member, \
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container_key_member, \
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function_name, \
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comparator) \
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void function_name(struct btree *tree, node_type *node) \
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{ \
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if (!tree->b_root) { \
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tree->b_root = &node->container_node_member; \
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btree_insert_fixup( \
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tree, \
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&node->container_node_member); \
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return; \
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} \
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\
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struct btree_node *cur = tree->b_root; \
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while (1) { \
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node_type *cur_node = BTREE_CONTAINER( \
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node_type, \
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container_node_member, \
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cur); \
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struct btree_node *next = NULL; \
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int cmp = comparator(node, cur_node); \
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\
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if (cmp == 1) { \
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next = btree_right(cur); \
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\
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if (!next) { \
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btree_put_right( \
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cur, \
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&node->container_node_member); \
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break; \
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} \
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} else if (cmp == -1) { \
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next = btree_left(cur); \
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\
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if (!next) { \
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btree_put_left( \
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cur, \
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&node->container_node_member); \
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break; \
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} \
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} else { \
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return; \
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} \
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\
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cur = next; \
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} \
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\
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btree_insert_fixup(tree, &node->container_node_member); \
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}
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/* defines a simple tree search function.
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this function assumes that your nodes have simple integer keys that can be
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compared with the usual operators.
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EXAMPLE:
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if you have a tree node type like this:
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struct my_tree_node {
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int key;
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struct btree_node base;
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}
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You would use the following call to generate a search function for a tree
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with this node type:
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BTREE_DEFINE_SIMPLE_GET(struct my_tree_node, int, base, key,
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my_tree_node_get);
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Which would emit a function defined like:
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static struct my_tree_node *my_tree_node_get(struct btree *tree, int key);
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@param node_type your custom tree node type. usually a structure that
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contains a struct btree_node member.
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@param key_type the type name of the key embedded in your custom tree node
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type. this type must be compatible with the builtin comparison operators.
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@param container_node_member the name of the struct btree_node member
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variable within your custom type.
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@param container_key_member the name of the key member variable within your
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custom type.
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@param function_name the name of the function to generate.
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*/
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#define BTREE_DEFINE_SIMPLE_GET( \
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node_type, \
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key_type, \
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container_node_member, \
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container_key_member, \
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function_name) \
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node_type *function_name(struct btree *tree, key_type key) \
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{ \
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struct btree_node *cur = tree->b_root; \
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while (cur) { \
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node_type *cur_node = BTREE_CONTAINER( \
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node_type, \
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container_node_member, \
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cur); \
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if (key > cur_node->container_key_member) { \
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cur = btree_right(cur); \
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} else if (key < cur_node->container_key_member) { \
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cur = btree_left(cur); \
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} else { \
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return cur_node; \
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} \
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} \
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\
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return NULL; \
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}
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/* perform an in-order traversal of a binary tree
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If you have a tree defined like:
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struct btree my_tree;
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with nodes defined like:
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struct my_tree_node {
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int key;
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struct btree_node base;
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}
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and you want to do something like:
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foreach (struct my_tree_node *node : my_tree) { ... }
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you should use this:
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btree_foreach (struct my_tree_node, node, &my_tree, base) { ... }
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@param iter_type the type name of the iterator variable. this should be the
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tree's node type, and shouldn't be a pointer.
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@param iter_name the name of the iterator variable.
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@param tree_name a pointer to the tree to traverse.
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@param node_member the name of the struct btree_node member variable within
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the tree node type.
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*/
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#define btree_foreach(iter_type, iter_name, tree_name, node_member) \
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for (iter_type *iter_name = BTREE_CONTAINER( \
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iter_type, \
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node_member, \
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btree_first(tree_name)); \
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iter_name; \
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iter_name = BTREE_CONTAINER( \
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iter_type, \
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node_member, \
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btree_next(&((iter_name)->node_member))))
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/* perform an reverse in-order traversal of a binary tree
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If you have a tree defined like:
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struct btree my_tree;
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with nodes defined like:
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struct my_tree_node {
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int key;
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struct btree_node base;
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}
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and you want to do something like:
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foreach (struct my_tree_node *node : reverse(my_tree)) { ... }
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you should use this:
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btree_foreach_r (struct my_tree_node, node, &my_tree, base) { ... }
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@param iter_type the type name of the iterator variable. this should be the
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tree's node type, and shouldn't be a pointer.
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@param iter_name the name of the iterator variable.
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@param tree_name a pointer to the tree to traverse.
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@param node_member the name of the struct btree_node member variable within
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the tree node type.
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*/
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#define btree_foreach_r(iter_type, iter_name, tree_name, node_member) \
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for (iter_type *iter_name \
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= BTREE_CONTAINER(iter_type, node_member, btree_last(tree_name)); \
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iter_name; \
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iter_name = BTREE_CONTAINER( \
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iter_type, \
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node_member, \
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btree_prev(&((iter_name)->node_member))))
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/* binary tree nodes. this *cannot* be used directly. you need to define a
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custom node type that contains a member variable of type struct btree_node.
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you would then use the supplied macros to define functions to manipulate your
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custom binary tree.
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*/
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struct btree_node {
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struct btree_node *b_parent, *b_left, *b_right;
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unsigned short b_height;
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};
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/* binary tree. unlike struct btree_node, you can define variables of type
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* struct btree. */
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struct btree {
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struct btree_node *b_root;
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};
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/* re-balance a binary tree after an insertion operation.
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NOTE that, if you define an insertion function using BTREE_DEFINE_INSERT or
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similar, this function will automatically called for you.
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@param tree the tree to re-balance.
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@param node the node that was just inserted into the tree.
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*/
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extern void btree_insert_fixup(struct btree *tree, struct btree_node *node);
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/* delete a node from a binary tree and re-balance the tree afterwards.
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@param tree the tree to delete from
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@param node the node to delete.
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*/
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extern void btree_delete(struct btree *tree, struct btree_node *node);
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/* get the first node in a binary tree.
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this will be the node with the smallest key (i.e. the node that is
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furthest-left from the root)
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*/
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extern struct btree_node *btree_first(struct btree *tree);
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/* get the last node in a binary tree.
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this will be the node with the largest key (i.e. the node that is
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furthest-right from the root)
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*/
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extern struct btree_node *btree_last(struct btree *tree);
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/* for any binary tree node, this function returns the node with the
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* next-largest key value */
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extern struct btree_node *btree_next(struct btree_node *node);
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/* for any binary tree node, this function returns the node with the
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* next-smallest key value */
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extern struct btree_node *btree_prev(struct btree_node *node);
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static inline bool btree_empty(const struct btree *tree)
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{
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return tree->b_root == NULL;
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}
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/* sets `child` as the immediate left-child of `parent` */
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static inline void btree_put_left(
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struct btree_node *parent,
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struct btree_node *child)
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{
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parent->b_left = child;
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child->b_parent = parent;
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}
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/* sets `child` as the immediate right-child of `parent` */
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static inline void btree_put_right(
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struct btree_node *parent,
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struct btree_node *child)
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{
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parent->b_right = child;
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child->b_parent = parent;
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}
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/* get the immediate left-child of `node` */
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static inline struct btree_node *btree_left(struct btree_node *node)
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{
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return node->b_left;
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}
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/* get the immediate right-child of `node` */
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static inline struct btree_node *btree_right(struct btree_node *node)
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{
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return node->b_right;
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}
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/* get the immediate parent of `node` */
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static inline struct btree_node *btree_parent(struct btree_node *node)
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{
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return node->b_parent;
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}
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/* get the height of `node`.
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the height of a node is defined as the length of the longest path
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between the node and a leaf node.
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this count includes the node itself, so the height of a leaf node will be 1.
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*/
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static inline unsigned short btree_height(struct btree_node *node)
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{
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return node->b_height;
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}
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#ifdef __cplusplus
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}
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#endif
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#endif
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