Tree::Simple::Visitor:UsermContributedTree::Simple::Visitor::FromNestedHash(3)NAMETree::Simple::Visitor::FromNestedHash - A Visitor for creating
Tree::Simple objects from nested hash trees.
SYNOPSIS
use Tree::Simple::Visitor::FromNestedHash;
my $visitor = Tree::Simple::Visitor::FromNestedHash->new();
# given this nested hash tree
my $hash_tree = {
Root => {
Child1 => {
GrandChild1 => {},
GrandChild2 => {}
},
Child2 => {}
}
};
# set the array tree we
# are going to convert
$visitor->setHashTree($hash_tree);
$tree->accept($visitor);
# this then creates the equivalent Tree::Simple object:
# Tree::Simple->new("Root")
# ->addChildren(
# Tree::Simple->new("Child1")
# ->addChildren(
# Tree::Simple->new("GrandChild1"),
# Tree::Simple->new("GrandChild2")
# ),
# Tree::Simple->new("Child2"),
# );
DESCRIPTION
Given a tree constructed from nested hashs, this Visitor will create
the equivalent Tree::Simple heirarchy.
METHODS
new There are no arguments to the constructor the object will be in its
default state. You can use the "setNodeFilter" methods to customize
its behavior.
setNodeFilter ($filter_function)
This method accepts a CODE reference as its $filter_function
argument and throws an exception if it is not a code reference.
This code reference is used to filter the tree nodes as they are
created, the $filter_function is passed the node value extracted
from the hash prior to it being inserted into the tree being built.
The $filter_function is expected to return the value desired for
inclusion into the tree.
setHashTree ($hash_tree)
This method is used to set the $hash_tree that our Tree::Simple
heirarchy will be constructed from. It must be in the following
form:
{
Root => {
Child1 => {
GrandChild1 => {},
GrandChild2 => {}
},
Child2 => {}
}
}
Basically each key in the hash is considered a node, values are
ignored unless it is a hash reference with at least one key in it,
in which case it is interpreted as containing the children of the
node created from the key.
The tree is validated prior being accepted, if it fails validation
an execption will be thrown. The rules are as follows;
The hash tree must not be empty.
It makes not sense to create a tree out of nothing, so it is
assumed that this is a sign of something wrong.
The hash tree must be a single rooted tree.
The hash tree should have only one key in it's first level, if
it has more than one, then it is not a single rooted tree.
NOTE: Hash keys are sorted ascii-betically before being added to
the tree, this results in a somewhat more predictable hierarchy.
visit ($tree)
This is the method that is used by Tree::Simple's "accept" method.
It can also be used on its own, it requires the $tree argument to
be a Tree::Simple object (or derived from a Tree::Simple object),
and will throw and exception otherwise.
BUGS
None that I am aware of. Of course, if you find a bug, let me know, and
I will be sure to fix it.
CODE COVERAGE
See the CODE COVERAGE section in Tree::Simple::VisitorFactory for more
inforamtion.
SEE ALSO
These Visitor classes are all subclasses of Tree::Simple::Visitor,
which can be found in the Tree::Simple module, you should refer to that
module for more information.
AUTHOR
stevan little, <stevan@iinteractive.com>
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.
perl v5.14.12005Tree::Simple::Visitor::FromNestedHash(3)
