#!/usr/bin/perl -w
# Using XML::Parser and Handlers
# Author: Ingo Macherius <macherius@gmd.de>
# updated by Michel Rodriguez <mirod@xmltwig.com>
use strict;

use XML::Parser;

# variables used to track the state of the parser
my( $in_lhs, $lhs, $in_rhs, $rhs, $i);

my $parser = XML::Parser->new(Handlers => { Start => \&tag_start,
	  End   => \&tag_end,
	  Char  => \&characters,
	});

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

sub tag_start {
	my ($xp, $el) = @_;

	if ($el eq 'rhs')     { $in_rhs = 1; } 
	elsif ($el eq 'lhs')  { $in_lhs = 1; }
	elsif ($el eq 'prod') { $rhs = ''; $lhs = ''; }
}

sub tag_end {
	my ($xp, $el) = @_;
	if ($el eq 'rhs')     { $in_rhs = 0; } 
	elsif ($el eq 'lhs')  { $in_lhs = 0; }
	elsif ($el eq 'prod') { print_production( ++$i, $lhs, $rhs); }
}

sub characters {
	my ($xp, $txt) = @_;
	if ($in_lhs)    { $lhs .= $txt }
	elsif ($in_rhs) { $rhs .= $txt }
}

sub print_production {
        my( $i, $lhs, $rhs)= @_;
	my $prod = "[$i] $lhs ::= $rhs";
	print clean( $prod) . "\n";
}


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