2 .\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
3 .\" All rights reserved.
5 .\" Redistribution and use in source and binary forms, with or without
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13 .\" 3. The name of the author may not be used to endorse or promote products
14 .\" derived from this software without specific prior written permission.
16 .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
17 .\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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27 .\" OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp
34 .Nm tsearch , tfind , tdelete , twalk
35 .Nd manipulate binary search trees
39 .Fn tdelete "const void * restrict key" "posix_tnode ** restrict rootp" "int (*compar) (const void *, const void *)"
41 .Fn tfind "const void *key" "posix_tnode * const *rootp" "int (*compar) (const void *, const void *)"
43 .Fn tsearch "const void *key" "posix_tnode **rootp" "int (*compar) (const void *, const void *)"
45 .Fn twalk "const posix_tnode *root" "void (*action) (const posix_tnode *, VISIT, int)"
53 functions manage binary search trees.
54 This implementation uses a balanced AVL tree,
55 which due to its strong theoretical limit on the height of the tree has
56 the advantage of calling the comparison function relatively
59 The comparison function passed in by
60 the user has the same style of return values as
66 searches for the datum matched by the argument
68 in the binary tree rooted at
70 returning a pointer to the datum if it is found and NULL
78 except that if no match is found,
80 is inserted into the tree and a pointer to it is returned.
83 points to a NULL value a new binary search tree is created.
88 deletes a node from the specified binary search tree and returns
89 a pointer to the parent of the node to be deleted.
90 It takes the same arguments as
94 If the node to be deleted is the root of the binary search tree,
101 walks the binary search tree rooted in
103 and calls the function
109 is called with three arguments: a pointer to the current node,
110 a value from the enum
111 .Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;"
112 specifying the traversal type, and a node level (where level
113 zero is the root of the tree).
117 function returns NULL if allocation of a new node fails (usually
118 due to a lack of free memory).
128 is NULL or the datum cannot be found.
132 function returns no value.
136 to search for four strings in
138 Because the strings are not already present, they are added.
140 is called twice on the fourth string to demonstrate that a string is not added when it is already present.
142 is used to find the single instance of the fourth string, and
147 is used to return and display the resulting binary search tree.
154 comp(const void *a, const void *b)
161 printwalk(const posix_tnode * node, VISIT v, int __unused0)
164 if (v == postorder || v == leaf) {
165 printf("node: %s\en", *(char **)node);
172 posix_tnode *root = NULL;
174 char one[] = "blah1";
175 char two[] = "blah-2";
176 char three[] = "blah-3";
177 char four[] = "blah-4";
179 tsearch(one, &root, comp);
180 tsearch(two, &root, comp);
181 tsearch(three, &root, comp);
182 tsearch(four, &root, comp);
183 tsearch(four, &root, comp);
184 printf("four: %s\en", *(char **)tfind(four, &root, comp));
185 tdelete(four, &root, comp);
187 twalk(root, printwalk);
196 These functions conform to
203 but is expected to be standardized by future versions of the standard.
206 for source-level compatibility.
209 makes distinguishing between nodes and keys easier.