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	1	.\" $NetBSD$
	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	.\" $FreeBSD: src/lib/libc/stdlib/tsearch.3,v 1.12 2002/12/19 09:40:24 ru Exp $
	29	.\"
	30	.Dd June 15, 1997
	31	.Dt TSEARCH 3
	32	.Os
	33	.Sh NAME
	34	.Nm tsearch , tfind , tdelete , twalk
	35	.Nd manipulate binary search trees
	36	.Sh SYNOPSIS
	37	.In search.h
	38	.Ft void *
	39	.Fn tdelete "const void * restrict key" "void ** restrict rootp" "int (compar) (const void , const void *)"
	40	.Ft void *
	41	.Fn tfind "const void key" "void const rootp" "int (compar) (const void , const void )"
	42	.Ft void *
	43	.Fn tsearch "const void key" "void rootp" "int (compar) (const void , const void )"
	44	.Ft void
	45	.Fn twalk "const void root" "void (compar) (const void *, VISIT, int)"
	46	.Sh DESCRIPTION
	47	The
	48	.Fn tdelete ,
	49	.Fn tfind ,
	50	.Fn tsearch ,
	51	and
	52	.Fn twalk
	53	functions manage binary search trees based on algorithms T and D
	54	from Knuth (6.2.2). The comparison function passed in by
	55	the user has the same style of return values as
	56	.Xr strcmp 3 .
	57	.Pp
	58	The
	59	.Fn tfind
	60	function
	61	searches for the datum matched by the argument
	62	.Fa key
	63	in the binary tree rooted at
	64	.Fa rootp ,
	65	returning a pointer to the datum if it is found and NULL
	66	if it is not.
	67	.Pp
	68	The
	69	.Fn tsearch
	70	function
	71	is identical to
	72	.Fn tfind
	73	except that if no match is found,
	74	.Fa key
	75	is inserted into the tree and a pointer to it is returned. If
	76	.Fa rootp
	77	points to a NULL value a new binary search tree is created.
	78	.Pp
	79	The
	80	.Fn tdelete
	81	function
	82	deletes a node from the specified binary search tree and returns
	83	a pointer to the parent of the node to be deleted.
	84	It takes the same arguments as
	85	.Fn tfind
	86	and
	87	.Fn tsearch .
	88	If the node to be deleted is the root of the binary search tree,
	89	.Fa rootp
	90	will be adjusted.
	91	.Pp
	92	The
	93	.Fn twalk
	94	function
	95	walks the binary search tree rooted in
	96	.Fa root
	97	and calls the function
	98	.Fa action
	99	on each node.
	100	The
	101	.Fa action
	102	function
	103	is called with three arguments: a pointer to the current node,
	104	a value from the enum
	105	.Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;"
	106	specifying the traversal type, and a node level (where level
	107	zero is the root of the tree).
	108	.Sh SEE ALSO
	109	.Xr bsearch 3 ,
	110	.Xr hsearch 3 ,
	111	.Xr lsearch 3
	112	.Sh RETURN VALUES
	113	The
	114	.Fn tsearch
	115	function returns NULL if allocation of a new node fails (usually
	116	due to a lack of free memory).
	117	.Pp
	118	The
	119	.Fn tfind ,
	120	.Fn tsearch ,
	121	and
	122	.Fn tdelete
	123	functions
	124	return NULL if
	125	.Fa rootp
	126	is NULL or the datum cannot be found.
	127	.Pp
	128	The
	129	.Fn twalk
	130	function returns no value.