NAME¶
Tree::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.