fad4b12b90
to the traditional tree(3) RB trees, but using an array (preallocated, linear chunk of memory) to store the tree. This avoids allocation overhead, improves memory locality, and makes it trivially easy to share/transfer/copy the entire tree without the need for marshalling. The downside is that the size is fixed at initialization time; there is no mechanism to resize it. This is one of the dependencies for the new stats(3) framework (https://reviews.freebsd.org/D20477). Reviewed by: bcr (man pages), markj Discussed with: cem MFC after: 2 weeks Sponsored by: Klara Inc, Netflix Obtained from: Netflix Differential Revision: https://reviews.freebsd.org/D20324
484 lines
13 KiB
Groff
484 lines
13 KiB
Groff
.\" $OpenBSD: tree.3,v 1.7 2002/06/12 01:09:20 provos Exp $
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.\"
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.\" Copyright 2002 Niels Provos <provos@citi.umich.edu>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Niels Provos.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 8, 2019
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.Dt ARB 3
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.Os
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.Sh NAME
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.Nm ARB_PROTOTYPE ,
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.Nm ARB_PROTOTYPE_STATIC ,
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.Nm ARB_PROTOTYPE_INSERT ,
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.Nm ARB_PROTOTYPE_INSERT_COLOR ,
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.Nm ARB_PROTOTYPE_REMOVE ,
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.Nm ARB_PROTOTYPE_REMOVE_COLOR ,
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.Nm ARB_PROTOTYPE_FIND ,
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.Nm ARB_PROTOTYPE_NFIND ,
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.Nm ARB_PROTOTYPE_NEXT ,
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.Nm ARB_PROTOTYPE_PREV ,
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.Nm ARB_PROTOTYPE_MINMAX ,
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.Nm ARB_GENERATE ,
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.Nm ARB_GENERATE_STATIC ,
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.Nm ARB_GENERATE_INSERT ,
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.Nm ARB_GENERATE_INSERT_COLOR ,
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.Nm ARB_GENERATE_REMOVE ,
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.Nm ARB_GENERATE_REMOVE_COLOR ,
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.Nm ARB_GENERATE_FIND ,
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.Nm ARB_GENERATE_NFIND ,
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.Nm ARB_GENERATE_NEXT ,
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.Nm ARB_GENERATE_PREV ,
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.Nm ARB_GENERATE_MINMAX ,
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.Nm ARB8_ENTRY ,
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.Nm ARB16_ENTRY ,
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.Nm ARB32_ENTRY ,
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.Nm ARB8_HEAD ,
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.Nm ARB16_HEAD ,
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.Nm ARB32_HEAD ,
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.Nm ARB_ALLOCSIZE ,
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.Nm ARB_INITIALIZER ,
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.Nm ARB_ROOT ,
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.Nm ARB_EMPTY ,
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.Nm ARB_FULL ,
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.Nm ARB_CURNODES ,
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.Nm ARB_MAXNODES ,
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.Nm ARB_NEXT ,
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.Nm ARB_PREV ,
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.Nm ARB_MIN ,
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.Nm ARB_MAX ,
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.Nm ARB_FIND ,
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.Nm ARB_NFIND ,
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.Nm ARB_LEFT ,
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.Nm ARB_LEFTIDX ,
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.Nm ARB_RIGHT ,
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.Nm ARB_RIGHTIDX ,
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.Nm ARB_PARENT ,
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.Nm ARB_PARENTIDX ,
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.Nm ARB_GETFREE ,
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.Nm ARB_FREEIDX ,
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.Nm ARB_FOREACH ,
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.Nm ARB_FOREACH_FROM ,
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.Nm ARB_FOREACH_SAFE ,
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.Nm ARB_FOREACH_REVERSE ,
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.Nm ARB_FOREACH_REVERSE_FROM ,
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.Nm ARB_FOREACH_REVERSE_SAFE ,
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.Nm ARB_INIT ,
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.Nm ARB_INSERT ,
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.Nm ARB_REMOVE
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.Nd "array-based red-black trees"
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.Sh SYNOPSIS
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.In sys/arb.h
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.Fn ARB_PROTOTYPE NAME TYPE FIELD CMP
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.Fn ARB_PROTOTYPE_STATIC NAME TYPE FIELD CMP
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.Fn ARB_PROTOTYPE_INSERT NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_INSERT_COLOR NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_REMOVE NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_REMOVE_COLOR NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_FIND NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_NFIND NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_NEXT NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_PREV NAME TYPE ATTR
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.Fn ARB_PROTOTYPE_MINMAX NAME TYPE ATTR
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.Fn ARB_GENERATE NAME TYPE FIELD CMP
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.Fn ARB_GENERATE_STATIC NAME TYPE FIELD CMP
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.Fn ARB_GENERATE_INSERT NAME TYPE FIELD CMP ATTR
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.Fn ARB_GENERATE_INSERT_COLOR NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_REMOVE NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_REMOVE_COLOR NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_FIND NAME TYPE FIELD CMP ATTR
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.Fn ARB_GENERATE_NFIND NAME TYPE FIELD CMP ATTR
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.Fn ARB_GENERATE_NEXT NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_PREV NAME TYPE FIELD ATTR
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.Fn ARB_GENERATE_MINMAX NAME TYPE FIELD ATTR
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.Fn ARB<8|16|32>_ENTRY
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.Fn ARB<8|16|32>_HEAD HEADNAME TYPE
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.Ft "size_t"
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.Fn ARB_ALLOCSIZE "ARB_HEAD *head" "int<8|16|32>_t maxnodes" "struct TYPE *elm"
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.Fn ARB_INITIALIZER "ARB_HEAD *head" "int<8|16|32>_t maxnodes"
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.Ft "struct TYPE *"
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.Fn ARB_ROOT "ARB_HEAD *head"
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.Ft "bool"
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.Fn ARB_EMPTY "ARB_HEAD *head"
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.Ft "bool"
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.Fn ARB_FULL "ARB_HEAD *head"
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.Ft "int<8|16|32>_t"
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.Fn ARB_CURNODES "ARB_HEAD *head"
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.Ft "int<8|16|32>_t"
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.Fn ARB_MAXNODES "ARB_HEAD *head"
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.Ft "struct TYPE *"
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.Fn ARB_NEXT NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_PREV NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_MIN NAME "ARB_HEAD *head"
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.Ft "struct TYPE *"
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.Fn ARB_MAX NAME "ARB_HEAD *head"
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.Ft "struct TYPE *"
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.Fn ARB_FIND NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_NFIND NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_LEFT "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "int<8|16|32>_t"
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.Fn ARB_LEFTIDX "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "struct TYPE *"
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.Fn ARB_RIGHT "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "int<8|16|32>_t"
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.Fn ARB_RIGHTIDX "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "struct TYPE *"
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.Fn ARB_PARENT "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "int<8|16|32>_t"
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.Fn ARB_PARENTIDX "struct TYPE *elm" "ARB_ENTRY NAME"
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.Ft "struct TYPE *"
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.Fn ARB_GETFREE "ARB_HEAD *head" "FIELD"
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.Ft "int<8|16|32>_t"
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.Fn ARB_FREEIDX "ARB_HEAD *head"
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.Fn ARB_FOREACH VARNAME NAME "ARB_HEAD *head"
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.Fn ARB_FOREACH_FROM "VARNAME" "NAME" "POS_VARNAME"
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.Fn ARB_FOREACH_SAFE "VARNAME" "NAME" "ARB_HEAD *head" "TEMP_VARNAME"
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.Fn ARB_FOREACH_REVERSE VARNAME NAME "ARB_HEAD *head"
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.Fn ARB_FOREACH_REVERSE_FROM "VARNAME" "NAME" "POS_VARNAME"
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.Fn ARB_FOREACH_REVERSE_SAFE "VARNAME" "NAME" "ARB_HEAD *head" "TEMP_VARNAME"
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.Ft void
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.Fn ARB_INIT "struct TYPE *elm" "FIELD" "ARB_HEAD *head" "int<8|16|32>_t maxnodes"
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.Ft "struct TYPE *"
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.Fn ARB_INSERT NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Ft "struct TYPE *"
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.Fn ARB_REMOVE NAME "ARB_HEAD *head" "struct TYPE *elm"
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.Sh DESCRIPTION
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These macros define data structures for and array-based red-black trees.
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They use a single, continuous chunk of memory, and are useful
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e.g., when the tree needs to be transferred between userspace and kernel.
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.Pp
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In the macro definitions,
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.Fa TYPE
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is the name tag of a user defined structure that must contain a field of type
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.Vt ARB_ENTRY ,
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named
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.Fa ENTRYNAME .
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The argument
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.Fa HEADNAME
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is the name tag of a user defined structure that must be declared
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using the
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.Fn ARB_HEAD
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macro.
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The argument
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.Fa NAME
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has to be a unique name prefix for every tree that is defined.
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.Pp
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The function prototypes are declared with
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.Fn ARB_PROTOTYPE ,
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or
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.Fn ARB_PROTOTYPE_STATIC .
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The function bodies are generated with
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.Fn ARB_GENERATE ,
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or
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.Fn ARB_GENERATE_STATIC .
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See the examples below for further explanation of how these macros are used.
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.Pp
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A red-black tree is a binary search tree with the node color as an
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extra attribute.
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It fulfills a set of conditions:
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.Bl -enum -offset indent
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.It
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Every search path from the root to a leaf consists of the same number of
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black nodes.
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.It
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Each red node (except for the root) has a black parent.
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.It
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Each leaf node is black.
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.El
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.Pp
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Every operation on a red-black tree is bounded as
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.Fn O "lg n" .
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The maximum height of a red-black tree is
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.Fn 2lg "n + 1" .
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.Pp
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.Fn ARB_*
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trees require entries to be allocated as an array, and uses array
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indices to link entries together.
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The maximum number of
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.Fn ARB_*
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tree entries is therefore constrained by the minimum of array size and choice of
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signed integer data type used to store array indices.
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Use
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.Fn ARB_ALLOCSIZE
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to compute the size of memory chunk to allocate.
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.Pp
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A red-black tree is headed by a structure defined by the
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.Fn ARB_HEAD
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macro.
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A
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structure is declared with either of the following:
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.Bd -ragged -offset indent
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.Fn ARB<8|16|32>_HEAD HEADNAME TYPE
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.Va head ;
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.Ed
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.Pp
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where
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.Fa HEADNAME
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is the name of the structure to be defined, and struct
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.Fa TYPE
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is the type of the elements to be inserted into the tree.
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.Pp
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The
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.Fn ARB_HEAD
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variant includes a suffix denoting the signed integer data type size
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.Pq in bits
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used to store array indices.
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For example,
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.Fn ARB_HEAD8
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creates a red-black tree head strucutre with 8-bit signed array indices capable
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of indexing up to 128 entries.
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.Pp
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The
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.Fn ARB_ENTRY
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macro declares a structure that allows elements to be connected in the tree.
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Similarly to the
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.Fn ARB<8|16|32>_HEAD
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macro, the
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.Fn ARB_ENTRY
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variant includes a suffix denoting the signed integer data type size
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.Pq in bits
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used to store array indices.
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Entries should use the same number of bits as the tree head structure they will
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be linked into.
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.Pp
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In order to use the functions that manipulate the tree structure,
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their prototypes need to be declared with the
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.Fn ARB_PROTOTYPE
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or
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.Fn ARB_PROTOTYPE_STATIC
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macro,
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where
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.Fa NAME
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is a unique identifier for this particular tree.
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The
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.Fa TYPE
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argument is the type of the structure that is being managed
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by the tree.
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The
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.Fa FIELD
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argument is the name of the element defined by
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.Fn ARB_ENTRY .
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Individual prototypes can be declared with
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.Fn ARB_PROTOTYPE_INSERT ,
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.Fn ARB_PROTOTYPE_INSERT_COLOR ,
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.Fn ARB_PROTOTYPE_REMOVE ,
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.Fn ARB_PROTOTYPE_REMOVE_COLOR ,
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.Fn ARB_PROTOTYPE_FIND ,
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.Fn ARB_PROTOTYPE_NFIND ,
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.Fn ARB_PROTOTYPE_NEXT ,
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.Fn ARB_PROTOTYPE_PREV ,
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and
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.Fn ARB_PROTOTYPE_MINMAX
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in case not all functions are required.
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The individual prototype macros expect
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.Fa NAME ,
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.Fa TYPE ,
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and
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.Fa ATTR
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arguments.
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The
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.Fa ATTR
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argument must be empty for global functions or
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.Fa static
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for static functions.
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.Pp
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The function bodies are generated with the
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.Fn ARB_GENERATE
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or
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.Fn ARB_GENERATE_STATIC
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macro.
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These macros take the same arguments as the
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.Fn ARB_PROTOTYPE
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and
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.Fn ARB_PROTOTYPE_STATIC
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macros, but should be used only once.
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As an alternative individual function bodies are generated with the
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.Fn ARB_GENERATE_INSERT ,
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.Fn ARB_GENERATE_INSERT_COLOR ,
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.Fn ARB_GENERATE_REMOVE ,
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.Fn ARB_GENERATE_REMOVE_COLOR ,
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.Fn ARB_GENERATE_FIND ,
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.Fn ARB_GENERATE_NFIND ,
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.Fn ARB_GENERATE_NEXT ,
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.Fn ARB_GENERATE_PREV ,
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and
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.Fn ARB_GENERATE_MINMAX
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macros.
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.Pp
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Finally,
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the
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.Fa CMP
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argument is the name of a function used to compare tree nodes
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with each other.
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The function takes two arguments of type
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.Vt "struct TYPE *" .
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If the first argument is smaller than the second, the function returns a
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value smaller than zero.
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If they are equal, the function returns zero.
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Otherwise, it should return a value greater than zero.
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The compare
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function defines the order of the tree elements.
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.Pp
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The
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.Fn ARB_INIT
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macro initializes the tree referenced by
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.Fa head ,
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with the array length of
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.Fa maxnodes .
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.Pp
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The red-black tree can also be initialized statically by using the
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.Fn ARB_INITIALIZER
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macro:
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.Bd -ragged -offset indent
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.Fn ARB<8|16|32>_HEAD HEADNAME TYPE
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.Va head
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=
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.Fn ARB_INITIALIZER &head maxnodes ;
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.Ed
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.Pp
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The
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.Fn ARB_INSERT
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macro inserts the new element
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.Fa elm
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into the tree.
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.Pp
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The
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.Fn ARB_REMOVE
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macro removes the element
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.Fa elm
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from the tree pointed by
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.Fa head .
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.Pp
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|
The
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.Fn ARB_FIND
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|
and
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.Fn ARB_NFIND
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macros can be used to find a particular element in the tree.
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.Bd -literal -offset indent
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struct TYPE find, *res;
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find.key = 30;
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res = RB_FIND(NAME, head, &find);
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.Ed
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|
.Pp
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|
The
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.Fn ARB_ROOT ,
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|
.Fn ARB_MIN ,
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.Fn ARB_MAX ,
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.Fn ARB_NEXT ,
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|
and
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|
.Fn ARB_PREV
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|
macros can be used to traverse the tree:
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|
.Pp
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|
.Dl "for (np = RB_MIN(NAME, &head); np != NULL; np = RB_NEXT(NAME, &head, np))"
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|
.Pp
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|
Or, for simplicity, one can use the
|
|
.Fn ARB_FOREACH
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|
or
|
|
.Fn ARB_FOREACH_REVERSE
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|
macro:
|
|
.Bd -ragged -offset indent
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|
.Fn RB_FOREACH np NAME head
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|
.Ed
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|
.Pp
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|
The macros
|
|
.Fn ARB_FOREACH_SAFE
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|
and
|
|
.Fn ARB_FOREACH_REVERSE_SAFE
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|
traverse the tree referenced by head
|
|
in a forward or reverse direction respectively,
|
|
assigning each element in turn to np.
|
|
However, unlike their unsafe counterparts,
|
|
they permit both the removal of np
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|
as well as freeing it from within the loop safely
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|
without interfering with the traversal.
|
|
.Pp
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|
Both
|
|
.Fn ARB_FOREACH_FROM
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|
and
|
|
.Fn ARB_FOREACH_REVERSE_FROM
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|
may be used to continue an interrupted traversal
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|
in a forward or reverse direction respectively.
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|
The head pointer is not required.
|
|
The pointer to the node from where to resume the traversal
|
|
should be passed as their last argument,
|
|
and will be overwritten to provide safe traversal.
|
|
.Pp
|
|
The
|
|
.Fn ARB_EMPTY
|
|
macro should be used to check whether a red-black tree is empty.
|
|
.Pp
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|
Given that ARB trees have an intrinsic upper bound on the number of entries,
|
|
some ARB-specific additional macros are defined.
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|
The
|
|
.Fn ARB_FULL
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|
macro returns a boolean indicating whether the current number of tree entries
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|
equals the tree's maximum.
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|
The
|
|
.Fn ARB_CURNODES
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|
and
|
|
.Fn ARB_MAXNODES
|
|
macros return the current and maximum number of entries respectively.
|
|
The
|
|
.Fn ARB_GETFREE
|
|
macro returns a pointer to the next free entry in the array of entries, ready to
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|
be linked into the tree.
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|
The
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|
.Fn ARB_INSERT
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|
returns
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.Dv NULL
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|
if the element was inserted in the tree successfully, otherwise they
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|
return a pointer to the element with the colliding key.
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|
.Pp
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|
Accordingly,
|
|
.Fn ARB_REMOVE
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|
returns the pointer to the removed element otherwise they return
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.Dv NULL
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|
to indicate an error.
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|
.Sh SEE ALSO
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|
.Xr queue 3 ,
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.Xr tree 3
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.Sh HISTORY
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The
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.Nm ARB
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macros first appeared in
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.Fx 13.0 .
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.Sh AUTHORS
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The
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.Nm ARB
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macros were implemented by
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.An Lawrence Stewart Aq Mt lstewart@FreeBSD.org ,
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based on
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.Xr tree 3
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macros written by
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.An Niels Provos .
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