NAME
Tree::Create::Callback - Create tree object by using a callback
VERSION
This document describes version 0.03 of Tree::Create::Callback (from Perl distribution Tree-Create-Callback), released on 2016-04-01.
SYNOPSIS
use Tree::Create::Callback qw(create_tree_using_callback);
use Tree::Object::Hash; # for nodes
# create a tree of height 4 containing 1 + 2 + 4 + 8 nodes
my $tree = create_tree_using_callback(
sub {
my ($parent, $level, $seniority) = @_;
# we should return ($node, $num_children)
return (Tree::Object::Hash->new, $level >= 3 ? 0:2);
}
);DESCRIPTION
Building a tree manually can be tedious: you have to connect the parent and the children nodes together:
my $root = My::TreeNode->new(...);
my $child1 = My::TreeNode->new(...);
my $child2 = My::TreeNode->new(...);
$root->children([$child1, $child2]);
$child1->parent($root);
$child2->parent($root);
my $grandchild1 = My::Class->new(...);
...This module provides a convenience function to build a tree of objects in a single command. You supply a callback to create node and the function will connect the parent and children nodes for you.
The callback is called with these arguments:
($parent, $level, $seniority)where $parent is the parent node object (or undef if creating the root node, which is the first time the callback is called), $level indicates the current depth of the tree (starting from 0 for the root node, then 1 for the root's children, then 2 for their children, and so on). You can use this argument to know where to stop creating nodes. $seniority indicates the position of the node against its sibling (0 means the node is the first child of its parent, 1 means the second, and so on). You can use this argument to perhaps customize the node according to its sibling order.
The callback should return a list:
($node, $num_children)where $node is the created node object (the object can be of any class but it must respond to parent and children, see Role::TinyCommons::Tree::Node for more details on the requirement), $num_children is an integer that specifies the number of children that this node should have (0 means this node is to be a leaf node). The children will be created when the function calls the callback again later for each child node.
FUNCTIONS
create_tree_using_callback($cb) => obj
HOMEPAGE
Please visit the project's homepage at https://metacpan.org/release/Tree-Create-Callback.
SOURCE
Source repository is at https://github.com/perlancar/perl-Tree-Create-Callback.
BUGS
Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Tree-Create-Callback
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
SEE ALSO
Other Tree::Create::* modules, e.g. Tree::Create::Size.
Other ways to create tree: Tree::FromStruct, Tree::FromText, Tree::FromTextLines.
AUTHOR
perlancar <perlancar@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2016 by perlancar@cpan.org.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.