Some days ago, someone was asking about web robots... I pointed him to some CPAN modules, including LWP::Simple and HTML::Parser. Well, this program isn't precisely a robot, but may provide some help.

Furthermore, it is supposed to be a spot of GraphViz and the related package GraphViz for the other monks. If you want a more complex tool to do such things, use WebStalker.

#!/usr/bin/perl


use strict;

# Did someone say 'robot'?
use LWP::Simple;
use HTML::Parser;
use URI;
use GraphViz;


my $start_page = 'http://localhost/~stefano/';
my $graph = GraphViz->new( width => 8, height => 8 );

my %is_known = ();
my @to_be_explored = ();
my $current;

# Formerly known as $explorer :)
# Rename it according to your sympathies :)
my $scout = HTML::Parser->new( 
          start_h => [sub 
                  { 
                  my $self = shift;
                  my ($tagname, $attr) = @_;
                  
                  if ($tagname eq "a") {

                      $attr->{href} =~ s/\#.*//;
                      $graph->add_edge($current, $attr->{href});

                      unshift @to_be_explored, $attr->{href};     
                  }
                  }, "self, tagname, attr"]);


push @to_be_explored, $start_page;

while (@to_be_explored) {
    
    $current = URI->new( shift @to_be_explored ); 
        
    if ( not $is_known{ $current } ) {
    $is_known{ $current }++;

    $graph->add_node( $current, 
              fontsize => 8,
              height => 0.5,
              wodth => 0.5);

    print "Exploring $current ($#to_be_explored)...\n"; 
    
    my $html_string = get( $current->abs( $start_page )) 
        || warn "Can't get page! - $!\n";
    $scout->parse( $html_string );
    }
}

open OUT, "> out.png" || die "Can't open file for output! - $!\n";
print OUT $graph->as_png;
close OUT;
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