Provided by: libtree-perl_1.01-0ubuntu2_all 
NAME
Tree::Fast - the fastest possible implementation of a tree in pure Perl
SYNOPSIS
my $tree = Tree->new( 'root' );
my $child = Tree->new( 'child' );
$tree->add_child( {}, $child );
$tree->add_child( { at => 0 }, Tree->new( 'first child' ) );
$tree->add_child( { at => -1 }, Tree->new( 'last child' ) );
my @children = $tree->children;
my @some_children = $tree->children( 0, 2 );
$tree->remove_child( 0 );
my @nodes = $tree->traverse( $tree->POST_ORDER );
my $traversal = $tree->traverse( $tree->POST_ORDER );
while ( my $node = $traversal->() ) {
# Do something with $node here
}
my $clone = $tree->clone;
my $mirror = $tree->clone->mirror;
DESCRIPTION
This is meant to be the core implementation for Tree, stripped down as much as possible.
There is no error-checking, bounds-checking, event-handling, convenience methods, or
anything else of the sort. If you want something fuller- featured, please look at Tree,
which is a wrapper around Tree::Fast.
METHODS
Constructor
new([$value])
This will return a Tree object. It will accept one parameter which, if passed, will
become the value (accessible by value()). All other parameters will be ignored.
If you call "$tree->new([$value])", it will instead call "clone()", then set the value
of the clone to $value.
clone()
This will return a clone of $tree. The clone will be a root tree, but all children
will be cloned.
If you call "Tree->clone([$value])", it will instead call "new()".
NOTE: the value is merely a shallow copy. This means that all references will be kept.
Behaviors
add_child($options, @nodes)
This will add all the @nodes as children of $tree. $options is a required hashref that
specifies options for add_child(). The optional parameters are:
• at
This specifies the index to add @nodes at. If specified, this will be passed into
splice(). The only exceptions are if this is 0, it will act as an unshift(). If it
is unset or undefined, it will act as a push().
remove_child($options, @nodes)
This will remove all the @nodes from the children of $tree. You can either pass in the
actual child object you wish to remove, the index of the child you wish to remove, or
a combination of both.
$options is a required hashref that specifies parameters for remove_child().
Currently, no parameters are used.
mirror()
This will modify the tree such that it is a mirror of what it was before. This means
that the order of all children is reversed.
NOTE: This is a destructive action. It will modify the tree's internal structure. If
you wish to get a mirror, yet keep the original tree intact, use "my $mirror =
$tree->clone->mirror;"
traverse( [$order] )
When called in list context ("my @traversal = $tree->traverse()"), this will return a
list of the nodes in the given traversal order. When called in scalar context ("my
$traversal = $tree->traverse()"), this will return a closure that will, over
successive calls, iterate over the nodes in the given traversal order. When finished
it will return false.
The default traversal order is pre-order.
The various traversal orders do the following steps:
• Pre-order (aka Prefix traversal)
This will return the node, then the first sub tree in pre-order traversal, then
the next sub tree, etc.
Use "$tree->PRE_ORDER" as the $order.
• Post-order (aka Prefix traversal)
This will return the each sub-tree in post-order traversal, then the node.
Use "$tree->POST_ORDER" as the $order.
• Level-order (aka Prefix traversal)
This will return the node, then the all children of the node, then all
grandchildren of the node, etc.
Use "$tree->LEVEL_ORDER" as the $order.
Accessors
• parent()
This will return the parent of $tree.
• children( [ $idx, [$idx, ..] ] )
This will return the children of $tree. If called in list context, it will return all
the children. If called in scalar context, it will return the number of children.
You may optionally pass in a list of indices to retrieve. This will return the
children in the order you asked for them. This is very much like an arrayslice.
• value()
This will return the value stored in the node.
• set_value([$value])
This will set the value stored in the node to $value, then return $self.
• meta()
This will return a hashref that can be used to store whatever metadata the client
wishes to store. For example, Tree::Persist::DB uses this to store database row ids.
It is recommended that you store your metadata in a subhashref and not in the top-
level metadata hashref, keyed by your package name. Tree::Persist does this, using a
unique key for each persistence layer associated with that tree. This will help
prevent clobbering of metadata.
NULL TREE
If you call "$self->parent" on a root node, it will return a Tree::Null object. This is an
implementation of the Null Object pattern optimized for usage with Forest. It will
evaluate as false in every case (using overload) and all methods called on it will return
a Tree::Null object.
Notes
• Tree::Null does not inherit from anything. This is so that all the methods will go
through AUTOLOAD vs. the actual method.
• However, calling isa() on a Tree::Null object will report that it is-a any object that
is either Tree or in the Tree:: hierarchy.
• The Tree::Null object is a singleton.
• The Tree::Null object is defined, though. I couldn't find a way to make it evaluate as
undefined. That may be a good thing.
CODE COVERAGE
Please see the relevant sections of Tree.
SUPPORT
Please see the relevant sections of Tree.
ACKNOWLEDGEMENTS
• Stevan Little for writing Tree::Simple, upon which Tree is based.
AUTHORS
Rob Kinyon <rob.kinyon@iinteractive.com>
Stevan Little <stevan.little@iinteractive.com>
Thanks to Infinity Interactive for generously donating our time.
COPYRIGHT AND LICENSE
Copyright 2004, 2005 by Infinity Interactive, Inc.
<http://www.iinteractive.com>
This library is free software; you can redistribute it and/or modify it under the same
terms as Perl itself.