#!/usr/bin/perl

use HTML::TreeBuilder::XPath;
use HTML::Element;
use HTML::Entities qw(decode_entities);

use Data::Dumper;

use strict;
use warnings;

my $html = &layer(3);
print $html->as_XML,"\n";

exit(0);

sub layer {
    my ($layer) = (@_);

    my $ul = HTML::Element->new('ul');
    my $li = HTML::Element->new('li');
    $li->push_content("Layer $layer");
    $ul->push_content($li);
    if($layer--) {
        my $h = &layer($layer);
        my @c = &unescape_entities($h);         # offending line
        print "Wrong structure:\n",Dumper(@c),"\n ----\n";
        exit(1);

        $ul->push_content($h);
    } else {
        my $foo = ' foo < bar';
        my $literal = HTML::Element->new('~literal', text=>$foo);
        $li->push_content($literal);
        $ul->push_content($li);
    }

    return($ul);
}

sub unescape_entities {
    my ($html) = (@_);

    my $tmp = HTML::TreeBuilder::XPath->new;
    $tmp->parse(decode_entities($html->as_XML));
    my @c = $tmp->findnodes('//body/*');
    print "Right structure:\n", Dumper(@c),"\n ----\n";
    $tmp->delete;

    return(@c);         # this is getting transformed
}