#!/usr/bin/perl -w
# Using XML::Parser and Handlers
# Author: Ingo Macherius <macherius@gmd.de>
use strict;
use XML::Parser;

my $state={}; # holds the "global" values like rhs, lhs and counter

my $parser = XML::Parser->new( 
               Handlers => 
	        { Start => sub { tag_start(  $state, @_) } ,
	          End   => sub { tag_end(    $state, @_) } ,
	          Char  => sub { characters( $state, @_) },
	          Init  => sub { init(       $state, @_) },
	        });

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

sub tag_start {
	my ($state, $p, $el) = @_;
	if ($el eq 'prod') { $state->{rhs} = ''; $state->{lhs} = ''; }
}

sub tag_end {
	my ($state, $p, $el) = @_;
	if ($el eq 'prod') {
               $state->{counter}++;
	       my $prod= "[$state->{counter}] $state->{lhs} ::=  $state->{rhs}";
	       print clean( $prod), "\n";
        }
}

sub characters {
	my ( $state, $p, $txt) = @_;
	if    ($p->within_element( 'lhs')) { $state->{lhs} .= $txt }
	elsif ($p->within_element( 'rhs')) { $state->{rhs} .= $txt }
}

sub init {
        my( $state, $p)= @_;
        $state->{counter} = 0;
}

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