NAME¶
Tree::RB - Perl implementation of the Red/Black tree, a type of balanced binary
search tree.
VERSION¶
This document describes Tree::RB version 0.500004
SYNOPSIS¶
use Tree::RB;
my $tree = Tree::RB->new;
$tree->put('France' => 'Paris');
$tree->put('England' => 'London');
$tree->put('Hungary' => 'Budapest');
$tree->put('Ireland' => 'Dublin');
$tree->put('Egypt' => 'Cairo');
$tree->put('Germany' => 'Berlin');
$tree->put('Alaska' => 'Anchorage'); # D'oh! Alaska isn't a Country
$tree->delete('Alaska');
print scalar $tree->get('Ireland'); # 'Dublin'
print $tree->min->key; # 'Egypt'
print $tree->max->key; # 'Ireland'
print $tree->size; # 6
# print items, ordered by key
my $it = $tree->iter;
while(my $node = $it->next) {
printf "key = %s, value = %s\n", $node->key, $node->val;
}
# print items in reverse order
$it = $tree->rev_iter;
while(my $node = $it->next) {
printf "key = %s, value = %s\n", $node->key, $node->val;
}
# Hash interface
tie my %capital, 'Tree::RB';
# or do this to store items in descending order
tie my %capital, 'Tree::RB', sub { $_[1] cmp $_[0] };
$capital{'France'} = 'Paris';
$capital{'England'} = 'London';
$capital{'Hungary'} = 'Budapest';
$capital{'Ireland'} = 'Dublin';
$capital{'Egypt'} = 'Cairo';
$capital{'Germany'} = 'Berlin';
# print items in order
while(my ($key, $val) = each %capital) {
printf "key = $key, value = $val\n";
}
DESCRIPTION¶
This is a Perl implementation of the Red/Black tree, a type of balanced binary
search tree.
A tied hash interface is also provided to allow ordered hashes to be used.
See the Wikipedia article at <
http://en.wikipedia.org/wiki/Red-black_tree>
for more on Red/Black trees.
INTERFACE¶
new([CODEREF])¶
Creates and returns a new tree. If a reference to a subroutine is passed to
new(), the subroutine will be used to override the tree's default
lexical ordering and provide a user a defined ordering.
This subroutine should be just like a comparator subroutine used with sort,
except that it doesn't do the $a, $b trick.
For example, to get a case insensitive ordering
my $tree = Tree::RB->new(sub { lc $_[0] cmp lc $_[1]});
$tree->put('Wall' => 'Larry');
$tree->put('Smith' => 'Agent');
$tree->put('mouse' => 'micky');
$tree->put('duck' => 'donald');
my $it = $tree->iter;
while(my $node = $it->next) {
printf "key = %s, value = %s\n", $node->key, $node->val;
}
resort(CODEREF)¶
Changes the ordering of nodes within the tree. The new ordering is specified by
a comparator subroutine which must be passed to
resort().
See "new" for further information about the comparator.
size()¶
Returns the number of nodes in the tree.
root()¶
Returns the root node of the tree. This will either be undef if no nodes have
been added to the tree, or a Tree::RB::Node object. See the Tree::RB::Node
manual page for details on the Node object.
min()¶
Returns the node with the minimal key.
max()¶
Returns the node with the maximal key.
lookup(KEY, [MODE])¶
When called in scalar context, lookup(KEY) returns the value associated with
KEY.
When called in list context, lookup(KEY) returns a list whose first element is
the value associated with KEY, and whose second element is the node containing
the key/value.
An optional MODE parameter can be passed to
lookup() to influence which
key is returned.
The values of MODE are constants that are exported on demand by Tree::RB
use Tree::RB qw[LUEQUAL LUGTEQ LULTEQ LUGREAT LULESS LUNEXT LUPREV];
- LUEQUAL
- Returns node exactly matching the key.
- LUGTEQ
- Returns the node exactly matching the specified key, if this is not found
then the next node that is greater than the specified key is
returned.
- LULTEQ
- Returns the node exactly matching the specified key, if this is not found
then the next node that is less than the specified key is returned.
- LUGREAT
- Returns the node that is just greater than the specified key - not equal
to. This mode is similar to LUNEXT except that the specified key need not
exist in the tree.
- LULESS
- Returns the node that is just less than the specified key - not equal to.
This mode is similar to LUPREV except that the specified key need not
exist in the tree.
- LUNEXT
- Looks for the key specified, if not found returns "undef". If
the node is found returns the next node that is greater than the one found
(or "undef" if there is no next node).
This can be used to step through the tree in order.
- LUPREV
- Looks for the key specified, if not found returns "undef". If
the node is found returns the previous node that is less than the one
found (or "undef" if there is no previous node).
This can be used to step through the tree in reverse order.
get(KEY)¶
get() is an alias for
lookup().
iter([KEY])¶
Returns an iterator object that can be used to traverse the tree in order.
The iterator object supports a 'next' method that returns the next node in the
tree or undef if all of the nodes have been visited.
See the synopsis for an example.
If a key is supplied, the iterator returned will traverse the tree in order
starting from the node with key greater than or equal to the specified key.
$it = $tree->iter('France');
my $node = $it->next;
print $node->key; # -> 'France'
rev_iter([KEY])¶
Returns an iterator object that can be used to traverse the tree in reverse
order.
If a key is supplied, the iterator returned will traverse the tree in order
starting from the node with key less than or equal to the specified key.
$it = $tree->rev_iter('France');
my $node = $it->next;
print $node->key; # -> 'France'
$it = $tree->rev_iter('Finland');
my $node = $it->next;
print $node->key; # -> 'England'
hseek(KEY, [{-reverse => 1|0}])¶
For tied hashes, determines the next entry to be returned by each.
tie my %capital, 'Tree::RB';
$capital{'France'} = 'Paris';
$capital{'England'} = 'London';
$capital{'Hungary'} = 'Budapest';
$capital{'Ireland'} = 'Dublin';
$capital{'Egypt'} = 'Cairo';
$capital{'Germany'} = 'Berlin';
tied(%capital)->hseek('Germany');
($key, $val) = each %capital;
print "$key, $val"; # -> Germany, Berlin
The direction of iteration can be reversed by passing a hashref with key
'-reverse' and value 1 to hseek after or instead of KEY, e.g. to iterate over
the hash in reverse order:
tied(%capital)->hseek({-reverse => 1});
$key = each %capital;
print $key; # -> Ireland
The following calls are equivalent
tied(%capital)->hseek('Germany', {-reverse => 1});
tied(%capital)->hseek({-key => 'Germany', -reverse => 1});
put(KEY, VALUE)¶
Adds a new node to the tree.
The first argument is the key of the node, the second is its value.
If a node with that key already exists, its value is replaced with the given
value and the old value is returned. Otherwise, undef is returned.
delete(KEY)¶
If the tree has a node with the specified key, that node is deleted from the
tree and returned, otherwise "undef" is returned.
DEPENDENCIES¶
enum
INCOMPATIBILITIES¶
None reported.
BUGS AND LIMITATIONS¶
Please report any bugs or feature requests via the GitHub web interface at
<
https://github.com/arunbear/perl5-scalar-constant/issues>.
AUTHOR¶
Arun Prasad "<arunbear@cpan.org>"
Some documentation has been borrowed from Benjamin Holzman's Tree::RedBlack and
Damian Ivereigh's libredblack (<
http://libredblack.sourceforge.net/>).
ACKNOWLEDGEMENTS¶
Thanks for bug reports go to Anton Petrusevich, Wes Thompson, Petre Mierlutiu,
Tomer Vromen and Christopher Gurnee.
LICENCE AND COPYRIGHT¶
Copyright (c) 2007, Arun Prasad "<arunbear@cpan.org>". All
rights reserved.
This module is free software; you can redistribute it and/or modify it under the
same terms as Perl itself. See perlartistic.
DISCLAIMER OF WARRANTY¶
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE
SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE
STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE
SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR
IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO
THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE
PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR
CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY
COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE
SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES,
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