use strict;
use XML::Rules;

my $parser = XML::Rules->new(
	rules => [
		_default => '',                           # not interested in most tags
		nt => sub {$_[1]->{_content}},            # append the content to parent's content
		lhs => 'content',                         # add the <lhs> content to parent's attribute hash, using key "lhs"
		rhs => sub {'.rhs' => $_[1]->{_content}}, # append the <rhs> content to key "rhs" in the the parent's attribute hash
		prod => sub {
			my ($tag, $attrs, $context, $data, $parser) = @_;
			$parser->{pad}++;
			print clean("[$parser->{pad}] $attrs->{lhs} ::= $attrs->{rhs}")."\n";
			return;
		},
	],
	start_rules => [
		'header' => 'skip',                      # no point in parsing the <header> and its content, storing the data and throwing it away
		'spec' => sub {$_[4]->{pad} = 0; 1},     #initialization
	]
);

$parser->parsefile('REC-xml-19980210.xml');

sub clean {
        my( $string)= @_;
        $string =~ s/\xc2\xa0/ /sg;
        $string =~ s/\s+/ /g;
        $string=~ s{\s$}{}g;
        return $string;
}