1.\" $NetBSD: tsearch.3,v 1.12 2010/04/30 10:09:23 jruoho Exp $ 2.\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 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. 15.\" 16.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 17.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 18.\" AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 19.\" THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 20.\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22.\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp 28.\" 29.Dd April 30, 2010 30.Dt TSEARCH 3 31.Os 32.Sh NAME 33.Nm tsearch, tfind, tdelete, twalk 34.Nd manipulate binary search trees 35.Sh SYNOPSIS 36.In search.h 37.Ft void * 38.Fn tdelete "const void * restrict key" "void ** restrict rootp" "int (*compar) (const void *, const void *)" 39.Ft void * 40.Fn tfind "const void *key" "const void * const *rootp" "int (*compar) (const void *, const void *)" 41.Ft void * 42.Fn tsearch "const void *key" "void **rootp" "int (*compar) (const void *, const void *)" 43.Ft void 44.Fn twalk "const void *root" "void (*action) (const void *, VISIT, int)" 45.Sh DESCRIPTION 46The 47.Fn tdelete , 48.Fn tfind , 49.Fn tsearch , 50and 51.Fn twalk 52functions manage binary search trees based on algorithms T and D 53from Knuth (6.2.2). 54The comparison function passed in by 55the user has the same style of return values as 56.Xr strcmp 3 . 57.Pp 58.Fn tfind 59searches for the datum matched by the argument 60.Fa key 61in the binary tree rooted at 62.Fa rootp , 63returning a pointer to the datum if it is found and NULL 64if it is not. 65.Pp 66.Fn tsearch 67is identical to 68.Fn tfind 69except that if no match is found, 70.Fa key 71is inserted into the tree and a pointer to it is returned. 72If 73.Fa rootp 74points to a NULL value a new binary search tree is created. 75.Pp 76.Fn tdelete 77deletes a node from the specified binary search tree and returns 78a pointer to the parent of the node to be deleted. 79It takes the same arguments as 80.Fn tfind 81and 82.Fn tsearch . 83If the node to be deleted is the root of the binary search tree, 84.Fa rootp 85will be adjusted. 86.Pp 87.Fn twalk 88walks the binary search tree rooted in 89.Va root 90and calls the function 91.Fa action 92on each node. 93.Fa Action 94is called with three arguments: a pointer to the current node, 95a value from the enum 96.Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;" 97specifying the traversal type, and a node level (where level 98zero is the root of the tree). 99.Sh RETURN VALUES 100The 101.Fn tsearch 102function returns NULL if allocation of a new node fails (usually 103due to a lack of free memory). 104.Pp 105.Fn tfind , 106.Fn tsearch , 107and 108.Fn tdelete 109return NULL if 110.Fa rootp 111is NULL or the datum cannot be found. 112.Pp 113The 114.Fn twalk 115function returns no value. 116.Sh SEE ALSO 117.Xr bsearch 3 , 118.Xr hsearch 3 , 119.Xr lsearch 3 120.Sh STANDARDS 121These functions conform to 122.St -p1003.1-2001 . 123.Sh CAVEATS 124The 125.St -p1003.1-2001 126standard does not specify what value should be returned when deleting 127the root node. 128Since implementations vary, user of 129.Fn tdelete 130should not rely on any specific behaviour. 131The 132.St -p1003.1-2008 133revision tried to clarify the issue with the following wording: 134.Do 135the 136.Fn tdelete 137function shall return a pointer to the parent of the deleted node, 138or an unspecified non-NULL pointer if the deleted node was the root node, or a 139.Dv NULL 140pointer if the node is not found 141.Dc . 142