Index: head/lib/libc/stdlib/tsearch.3 =================================================================== --- head/lib/libc/stdlib/tsearch.3 (revision 320991) +++ head/lib/libc/stdlib/tsearch.3 (revision 320992) @@ -1,151 +1,209 @@ .\" $NetBSD$ .\" Copyright (c) 1997 Todd C. Miller .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, .\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY .\" AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL .\" THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, .\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, .\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; .\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, .\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR .\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF .\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp .\" $FreeBSD$ .\" -.Dd October 9, 2016 +.Dd June 4, 2017 .Dt TSEARCH 3 .Os .Sh NAME .Nm tsearch , tfind , tdelete , twalk .Nd manipulate binary search trees .Sh SYNOPSIS .In search.h .Ft void * .Fn tdelete "const void * restrict key" "posix_tnode ** restrict rootp" "int (*compar) (const void *, const void *)" .Ft posix_tnode * .Fn tfind "const void *key" "posix_tnode * const *rootp" "int (*compar) (const void *, const void *)" .Ft posix_tnode * .Fn tsearch "const void *key" "posix_tnode **rootp" "int (*compar) (const void *, const void *)" .Ft void .Fn twalk "const posix_tnode *root" "void (*action) (const posix_tnode *, VISIT, int)" .Sh DESCRIPTION The .Fn tdelete , .Fn tfind , .Fn tsearch , and .Fn twalk functions manage binary search trees. This implementation uses a balanced AVL tree, which due to its strong theoretical limit on the height of the tree has the advantage of calling the comparison function relatively infrequently. .Pp The comparison function passed in by the user has the same style of return values as .Xr strcmp 3 . .Pp The .Fn tfind function searches for the datum matched by the argument .Fa key in the binary tree rooted at .Fa rootp , returning a pointer to the datum if it is found and NULL if it is not. .Pp The .Fn tsearch function is identical to .Fn tfind except that if no match is found, .Fa key is inserted into the tree and a pointer to it is returned. If .Fa rootp points to a NULL value a new binary search tree is created. .Pp The .Fn tdelete function deletes a node from the specified binary search tree and returns a pointer to the parent of the node to be deleted. It takes the same arguments as .Fn tfind and .Fn tsearch . If the node to be deleted is the root of the binary search tree, .Fa rootp will be adjusted. .Pp The .Fn twalk function walks the binary search tree rooted in .Fa root and calls the function .Fa action on each node. The .Fa action function is called with three arguments: a pointer to the current node, a value from the enum .Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;" specifying the traversal type, and a node level (where level zero is the root of the tree). .Sh RETURN VALUES The .Fn tsearch function returns NULL if allocation of a new node fails (usually due to a lack of free memory). .Pp The .Fn tfind , .Fn tsearch , and .Fn tdelete functions return NULL if .Fa rootp is NULL or the datum cannot be found. .Pp The .Fn twalk function returns no value. +.Sh EXAMPLES +This example uses +.Fn tsearch +to search for four strings in +.Dv root . +Because the strings are not already present, they are added. +.Fn tsearch +is called twice on the fourth string to demonstrate that a string is not added when it is already present. +.Fn tfind +is used to find the single instance of the fourth string, and +.Fn tdelete +removes it. +Finally, +.Fn twalk +is used to return and display the resulting binary search tree. +.Bd -literal +#include +#include +#include + +int +comp(const void *a, const void *b) +{ + + return strcmp(a, b); +} + +void +printwalk(const posix_tnode * node, VISIT v, int __unused0) +{ + + if (v == postorder || v == leaf) { + printf("node: %s\n\\", *(char **)node); + } +} + +int +main(void) +{ + posix_tnode *root = NULL; + + char one[] = "blah1"; + char two[] = "blah-2"; + char three[] = "blah-3"; + char four[] = "blah-4"; + + tsearch(one, &root, comp); + tsearch(two, &root, comp); + tsearch(three, &root, comp); + tsearch(four, &root, comp); + tsearch(four, &root, comp); + printf("four: %s\n", *(char **)tfind(four, &root, comp)); + tdelete(four, &root, comp); + + twalk(root, printwalk); + return 0; +} +.Ed .Sh SEE ALSO .Xr bsearch 3 , .Xr hsearch 3 , .Xr lsearch 3 .Sh STANDARDS These functions conform to .St -p1003.1-2008 . .Pp The .Fa posix_tnode type is not part of .St -p1003.1-2008 , but is expected to be standardized by future versions of the standard. It is defined as .Fa void for source-level compatibility. Using .Fa posix_tnode makes distinguishing between nodes and keys easier.