#!/bin/perl -w

# author Michel Rodriguez <m.v.rodriguez@ieee.org>

use strict;


# Basic parsing and grove building
use XML::Grove::Builder;
use Data::Grove::Visitor;
use XML::Grove::AsString;
use XML::Parser::PerlSAX;

my $store= 0;
my $i=0;
my $prod;

my $grove_builder = XML::Grove::Builder->new;
my $parser        = XML::Parser::PerlSAX->new ( Handler => $grove_builder );
my $grove;

my $visitor = new TitleVisitor;              # create the visitor

# create the grove object
$grove= $parser->parse ( Source => { SystemId => 'REC-xml-19980210.xml' }  );  
$grove->accept( $visitor);                   # visit the grove


# This package is used by the $grove->accept call

package TitleVisitor;

sub new 
  { my $class = shift;
    return bless {}, $class;
  }

sub visit_document                            # first method called
  { my ($self, $grove)= @_;
    $grove->children_accept_name ($self);     # visit all children of the doc
  }

sub visit_element                             # called if no visit_element_<tag>exists for the element
  { my( $self, $element)= @_;                
    $element->children_accept_name ($self);   # visit children
  }

sub visit_characters 
  { my( $self, $characters)= @_;              # called for characters in elements
    $prod .= $characters->{Data} if( $store); # store the text when required
  }

sub visit_name_prod                           # called for elements prod
  { my( $self, $element )= @_;
    $i++;
    $prod= "[$i] ";
    $element->children_accept_name ($self);   # visit children, updates $prod
    print clean( $prod), "\n";
}

sub visit_name_lhs                            # called for elements lhs
  { my( $self, $element )= @_;
    $store= 1;                                # store text in lhs
    $element->children_accept_name ($self);
    $store= 0;
    $prod .= " ::= ";
  }

sub visit_name_rhs                            # called for elements lhs
  { my( $self, $element )= @_;
    $store= 1;                                # store text in lhs
    $element->children_accept_name ($self);
    $store= 0;
  }

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