File Coverage

blib/lib/EO/Hierarchy.pm

Criterion	Covered	Total	%
statement	7	9	77.7
branch			n/a
condition			n/a
subroutine	3	3	100.0
pod			n/a
total	10	12	83.3

package EO::Hierarchy;

use strict;
use warnings;

use EO::Hash;
use EO::delegate;
use base qw( EO );

our $VERSION = 0.96;

EO::Hierarchy->mk_accessors( qw( parent ) );

exception EO::Hierarchy::Error::NoParent;
exception EO::Hierarchy::Error::InvalidState;

sub init {
  my $self = shift;
  if ($self->SUPER::init( @_ )) {
    $self->delegate( EO::Hash->new );
    return 1;
  }
  return 0;
}

sub add_child {
  my $self = shift;
  my $name = shift;
  ## we want to share the delegated class, which makes this look
  ## sort of ugly, but not bad enough to make me want a 'class' method.
  ## on everything.
  my $child = ref($self)->new
                        ->delegate( ref($self->delegate)->new )
			->parent( $self );
  $self->at($name, $child);
}


## this took me a while to work out, so I'd better document it.
sub at {
  my $self = shift;
  my $key  = shift;

  throw EO::Error::InvalidParameters text => 'no key specified' unless defined( $key );

  if (@_) {
    ## if its a set, then we do just that, no
    ## need to worry about it.
    return $self->delegate->at( $key, @_ );
  }

  ## right, its a get, here is the fun.
  if ( !defined( $self->delegate->at( $key ) ) && $self->parent ) {
    ## if we don't have a defined value at the key, but
    ## we do have a parent then we ask the parent.
    return $self->parent->at( $key );
  } elsif (!defined( $self->delegate->at($key) ) && !$self->parent) {
    ## if we don't have a defined value at the key, and
    ## we have no parent, then we throw an Exception.
    throw EO::Hierarchy::Error::NoParent
      text => 'have gone as far as we can';
  } elsif (defined( $self->delegate->at( $key ) )) {
    ## if we have a key, then we return it
    return $self->delegate->at( $key );
  } else {
    ## we should absolutely never get here.  I don't know
    ## how we would get here, but it all seems hairy enough
    ## to warrant an exception.
    throw EO::Hierarchy::Error::InvalidState
      text => 'how the heck did we get here?'
  }
}

1;

__END__