use strict;
use XML::Rules;
my $filter = XML::Rules->new(
	style => 'filter',
	rules => {
		_default => 'raw',
		p => sub {
			my ($tag, $attr) = @_;
			if ($attr->{v} eq 'YES') {
				return $tag => $attr
			} else {
				return;
			}
		},
	},
);

$filter->filter(\*DATA);

__DATA__
<?xml version="1.0" encoding="UTF-8" ?>
<e>
    <p id="1" v="YES">
        <e1>The</e1>
        <e2>Bye</e2>
    </p>
    <p id="2" v="NO">
        <e1>Border</e1>
        <e2>Lamp</e2>
    </p>
</e>