[apple/libc.git] / stdlib / tsearch.3

.\" $NetBSD$
.\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
.\" 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: src/lib/libc/stdlib/tsearch.3,v 1.7 2001/09/07 14:46:36 asmodai Exp $
.\"
.Dd June 15, 1997
.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 *key" "void **rootp" "int (*compar) (const void *, const void *)"
.Ft void *
.Fn tfind "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"
.Ft void *
.Fn tsearch "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"
.Ft void
.Fn twalk "const void *root" "void (*compar) (const void *, VISIT, int)"
.Sh DESCRIPTION
The
.Fn tdelete ,
.Fn tfind ,
.Fn tsearch ,
and
.Fn twalk
functions manage binary search trees based on algorithms T and D
from Knuth (6.2.2).  The comparison function passed in by
the user has the same style of return values as
.Xr strcmp 3 .
.Pp
.Fn Tfind
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
.Fn Tsearch
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
.Fn Tdelete
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
.Fn Twalk
walks the binary search tree rooted in
.Fa root
and calls the function
.Fa action
on each node.
.Fa Action
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 SEE ALSO
.Xr bsearch 3 ,
.Xr hsearch 3 ,
.Xr lsearch 3
.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
.Fn Tfind ,
.Fn tsearch ,
and
.Fn tdelete
return NULL if
.Fa rootp
is NULL or the datum cannot be found.
.Pp
The
.Fn twalk
function returns no value.
Commit	Line	Data
5b2abdfb A	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 1.7 2001/09/07 14:46:36 asmodai 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 key" "void rootp" "int (compar) (const void , const void )"
	40	.Ft void *
	41	.Fn tfind "const void key" "void 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	.Fn Tfind
	59	searches for the datum matched by the argument
	60	.Fa key
	61	in the binary tree rooted at
	62	.Fa rootp ,
	63	returning a pointer to the datum if it is found and NULL
	64	if it is not.
65	.Pp
66	.Fn Tsearch
67	is identical to
68	.Fn tfind
69	except that if no match is found,
70	.Fa key
71	is inserted into the tree and a pointer to it is returned. If
72	.Fa rootp
73	points to a NULL value a new binary search tree is created.
74	.Pp
75	.Fn Tdelete
76	deletes a node from the specified binary search tree and returns
77	a pointer to the parent of the node to be deleted.
78	It takes the same arguments as
79	.Fn tfind
80	and
81	.Fn tsearch .
82	If the node to be deleted is the root of the binary search tree,
83	.Fa rootp
84	will be adjusted.
85	.Pp
86	.Fn Twalk
87	walks the binary search tree rooted in
88	.Fa root
89	and calls the function
90	.Fa action
91	on each node.
92	.Fa Action
93	is called with three arguments: a pointer to the current node,
94	a value from the enum
95	.Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;"
96	specifying the traversal type, and a node level (where level
97	zero is the root of the tree).
98	.Sh SEE ALSO
99	.Xr bsearch 3 ,
100	.Xr hsearch 3 ,
101	.Xr lsearch 3
102	.Sh RETURN VALUES
103	The
104	.Fn tsearch
105	function returns NULL if allocation of a new node fails (usually
106	due to a lack of free memory).
107	.Pp
108	.Fn Tfind ,
109	.Fn tsearch ,
110	and
111	.Fn tdelete
112	return NULL if
113	.Fa rootp
114	is NULL or the datum cannot be found.
115	.Pp
116	The
117	.Fn twalk
118	function returns no value.