2 .\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
3 .\" All rights reserved.
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27 .\" OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp
33 .Nm tsearch , tfind , tdelete , twalk
34 .Nd manipulate binary search trees
38 .Fn tdelete "const void * restrict key" "posix_tnode ** restrict rootp" "int (*compar) (const void *, const void *)"
40 .Fn tfind "const void *key" "posix_tnode * const *rootp" "int (*compar) (const void *, const void *)"
42 .Fn tsearch "const void *key" "posix_tnode **rootp" "int (*compar) (const void *, const void *)"
44 .Fn twalk "const posix_tnode *root" "void (*action) (const posix_tnode *, VISIT, int)"
52 functions manage binary search trees.
53 This implementation uses a balanced AVL tree,
54 which due to its strong theoretical limit on the height of the tree has
55 the advantage of calling the comparison function relatively
58 The comparison function passed in by
59 the user has the same style of return values as
65 searches for the datum matched by the argument
67 in the binary tree rooted at
69 returning a pointer to the datum if it is found and NULL
77 except that if no match is found,
79 is inserted into the tree and a pointer to it is returned.
82 points to a NULL value a new binary search tree is created.
87 deletes a node from the specified binary search tree and returns
88 a pointer to the parent of the node to be deleted.
89 It takes the same arguments as
93 If the node to be deleted is the root of the binary search tree,
100 walks the binary search tree rooted in
102 and calls the function
108 is called with three arguments: a pointer to the current node,
109 a value from the enum
110 .Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;"
111 specifying the traversal type, and a node level (where level
112 zero is the root of the tree).
116 function returns NULL if allocation of a new node fails (usually
117 due to a lack of free memory).
127 is NULL or the datum cannot be found.
131 function returns no value.
135 to search for four strings in
137 Because the strings are not already present, they are added.
139 is called twice on the fourth string to demonstrate that a string is not added when it is already present.
141 is used to find the single instance of the fourth string, and
146 is used to return and display the resulting binary search tree.
153 comp(const void *a, const void *b)
160 printwalk(const posix_tnode * node, VISIT v, int __unused0)
163 if (v == postorder || v == leaf) {
164 printf("node: %s\en", *(char **)node);
171 posix_tnode *root = NULL;
173 char one[] = "blah1";
174 char two[] = "blah-2";
175 char three[] = "blah-3";
176 char four[] = "blah-4";
178 tsearch(one, &root, comp);
179 tsearch(two, &root, comp);
180 tsearch(three, &root, comp);
181 tsearch(four, &root, comp);
182 tsearch(four, &root, comp);
183 printf("four: %s\en", *(char **)tfind(four, &root, comp));
184 tdelete(four, &root, comp);
186 twalk(root, printwalk);
195 These functions conform to
202 but is expected to be standardized by future versions of the standard.
205 for source-level compatibility.
208 makes distinguishing between nodes and keys easier.