6b6ac9438f
package does have BXA export approval, but the licensing strings on the dnssafe code are a bit unpleasant. The crypto is easy to restore and bind will run without it - just without full dnssec support. Obtained from: The Internet Software Consortium (www.isc.org)
155 lines
5.2 KiB
Plaintext
155 lines
5.2 KiB
Plaintext
.\" $Id: tree.mdoc,v 8.2 1999/01/08 19:25:48 vixie Exp $
|
|
.\"
|
|
.\"Copyright (c) 1995-1999 by Internet Software Consortium
|
|
.\"
|
|
.\"Permission to use, copy, modify, and distribute this software for any
|
|
.\"purpose with or without fee is hereby granted, provided that the above
|
|
.\"copyright notice and this permission notice appear in all copies.
|
|
.\"
|
|
.\"THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
|
|
.\"ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
|
|
.\"OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
|
|
.\"CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
|
|
.\"DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
|
|
.\"PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
|
|
.\"ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
|
|
.\"SOFTWARE.
|
|
.\"
|
|
.Dd April 5, 1994
|
|
.Dt TREE 3
|
|
.Os BSD 4
|
|
.Sh NAME
|
|
.Nm tree_init ,
|
|
.Nm tree_mung ,
|
|
.Nm tree_srch ,
|
|
.Nm tree_add ,
|
|
.Nm tree_delete ,
|
|
.Nm tree_trav
|
|
.Nd balanced binary tree routines
|
|
.Sh SYNOPSIS
|
|
.Ft void
|
|
.Fn tree_init "void **tree"
|
|
.Ft void *
|
|
.Fn tree_srch "void **tree" "int (*compare)()" "void *data"
|
|
.Ft void
|
|
.Fn tree_add(tree, compare, data, del_uar) "void **tree" "int (*compare)()" \
|
|
"void *data" "void (*del_uar)()"
|
|
.Ft int
|
|
.Fn tree_delete(tree, compare, data, del_uar) "void **tree" "int (*compare)()" \
|
|
"void *data" "void (*del_uar)()"
|
|
.Ft int
|
|
.Fn tree_trav(tree, trav_uar) "void **tree" "int (*trav_uar)()"
|
|
.Ft void
|
|
.Fn tree_mung(tree, del_uar) "void **tree" "void (*del_uar)()"
|
|
.Sh DESCRIPTION
|
|
These functions create and manipulate a balanced binary (AVL) tree. Each node
|
|
of the tree contains the expected left & right subtree pointers, a short int
|
|
balance indicator, and a pointer to the user data. On a 32 bit system, this
|
|
means an overhead of 4+4+2+4 bytes per node (or, on a RISC or otherwise
|
|
alignment constrained system with implied padding, 4+4+4+4 bytes per node).
|
|
There is no key data type enforced by this package; a caller supplied
|
|
compare routine is used to compare user data blocks.
|
|
.Pp
|
|
Balanced binary trees are very fast on searches and replacements, but have a
|
|
moderately high cost for additions and deletions. If your application does a
|
|
lot more searches and replacements than it does additions and deletions, the
|
|
balanced (AVL) binary tree is a good choice for a data structure.
|
|
.Pp
|
|
.Fn Tree_init
|
|
creates an empty tree and binds it to
|
|
.Dq Fa tree
|
|
(which for this and all other routines in this package should be declared as
|
|
a pointer to void or int, and passed by reference), which can then be used by
|
|
other routines in this package. Note that more than one
|
|
.Dq Fa tree
|
|
variable can exist at once; thus multiple trees can be manipulated
|
|
simultaneously.
|
|
.Pp
|
|
.Fn Tree_srch
|
|
searches a tree for a specific node and returns either
|
|
.Fa NULL
|
|
if no node was found, or the value of the user data pointer if the node
|
|
was found.
|
|
.Fn compare
|
|
is the address of a function to compare two user data blocks. This routine
|
|
should work much the way
|
|
.Xr strcmp 3
|
|
does; in fact,
|
|
.Xr strcmp
|
|
could be used if the user data was a \s-2NUL\s+2 terminated string.
|
|
.Dq Fa Data
|
|
is the address of a user data block to be used by
|
|
.Fn compare
|
|
as the search criteria. The tree is searched for a node where
|
|
.Fn compare
|
|
returns 0.
|
|
.Pp
|
|
.Fn Tree_add
|
|
inserts or replaces a node in the specified tree. The tree specified by
|
|
.Dq Fa tree
|
|
is searched as in
|
|
.Fn tree_srch,
|
|
and if a node is found to match
|
|
.Dq Fa data,
|
|
then the
|
|
.Fn del_uar
|
|
function, if non\-\s-2NULL\s+2, is called with the address of the user data
|
|
block for the node (this routine should deallocate any dynamic memory which
|
|
is referenced exclusively by the node); the user data pointer for the node
|
|
is then replaced by the value of
|
|
.Dq Fa data.
|
|
If no node is found to match, a new node is added (which may or may not
|
|
cause a transparent rebalance operation), with a user data pointer equal to
|
|
.Dq Fa data.
|
|
A rebalance may or may not occur, depending on where the node is added
|
|
and what the rest of the tree looks like.
|
|
.Fn Tree_add
|
|
will return the
|
|
.Dq Fa data
|
|
pointer unless catastrophe occurs in which case it will return \s-2NULL\s+2.
|
|
.Pp
|
|
.Fn Tree_delete
|
|
deletes a node from
|
|
.Dq Fa tree.
|
|
A rebalance may or may not occur, depending on where the node is removed from
|
|
and what the rest of the tree looks like.
|
|
.Fn Tree_delete
|
|
returns TRUE if a node was deleted, FALSE otherwise.
|
|
.Pp
|
|
.Fn Tree_trav
|
|
traverses all of
|
|
.Dq Fa tree,
|
|
calling
|
|
.Fn trav_uar
|
|
with the address of each user data block. If
|
|
.Fn trav_uar
|
|
returns FALSE at any time,
|
|
.Fn tree_trav
|
|
will immediately return FALSE to its caller. Otherwise all nodes will be
|
|
reached and
|
|
.Fn tree_trav
|
|
will return TRUE.
|
|
.Pp
|
|
.Fn Tree_mung
|
|
deletes every node in
|
|
.Dq Fa tree,
|
|
calling
|
|
.Fn del_uar
|
|
(if it is not \s-2NULL\s+2) with the user data address from each node (see
|
|
.Fn tree_add
|
|
and
|
|
.Fn tree_delete
|
|
above). The tree is left in the same state that
|
|
.Fn tree_init
|
|
leaves it in \- i.e., empty.
|
|
.Sh BUGS
|
|
Should have a way for the caller to specify application-specific
|
|
.Xr malloc
|
|
and
|
|
.Xr free
|
|
functions to be used internally when allocating meta data.
|
|
.Sh AUTHOR
|
|
Paul Vixie, converted and augumented from Modula\-2 examples in
|
|
.Dq Algorithms & Data Structures ,
|
|
Niklaus Wirth, Prentice\-Hall, ISBN 0\-13\-022005\-1.
|