my $parser =  XML::Rules->new (
  rules => [
    root => 'no content',
    parent => sub {$_[1]->{text} = delete $_[1]->{_content}; return '@
+parent' => $_[1]},
    ch1 => 'content array',
    ch2 => 'content array',
    ]
);
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The attributes are all in the hash referenced by $_[1], the $_[0] is just a string. So in the rule for <parent> you first move the text content from {_content} to {text} and then return the tag name and attributes prepending the '@' to make sure you end up with an array of parents. See the builtin rules in XML::Rules docs and especially the sub{} next to the 'as array' rule.