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# This file is part of Config::AST -*- perl -*-
# Copyright (C) 2017-2019 Sergey Poznyakoff <gray@gnu.org>
#
# Config::AST is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# Config::AST is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Config::AST. If not, see <http://www.gnu.org/licenses/>.
package Config::AST::Node::Null;
use parent 'Config::AST::Node';
use strict;
use warnings;
use Carp;
=head1 NAME
Config::AST::Node::Null - a null node
=head1 DESCRIPTION
Implements null node - a node returned by direct retrieval if the requested
node is not present in the tree.
In boolean context, null nodes evaluate to false.
=head1 METHODS
=head2 $node->is_null
Returns true.
=cut
sub is_null { 1 }
our $AUTOLOAD;
sub AUTOLOAD {
my $self = shift;
my $key = $AUTOLOAD;
$key =~ s/.*:://;
if ($key =~ s/^([A-Z])(.*)/\l$1$2/) {
return $self;
}
confess "Can't locate method $AUTOLOAD";
}
=head2 $node->as_string
Returns the string "(null)".
=cut
sub as_string { '(null)' }
=head2 $node->value
Returns C<undef>.
=cut
sub value { undef }
use overload
'""' => \&value,
bool => \&value,
'0+' => \&value,
fallback => 1;
=head1 SEE ALSO
B<Config::AST>,
B<Config::AST::Node>.
=cut
1;
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