## Concatenates the texts retrieved in a node's (possibly nested) descendants
# Note: preserve recursion with process_text_in($node)
sub get_all_text_in {
  my $node = shift;

  # Concatenate the texts extracted from each child node
  my $text = reduce { $a .= process_text_in($b) }
                    $node->content_list;
}

## Get the text in a node, processing it if needed
# Note: preserve recursion with get_all_text_in($node)
sub process_text_in {
  my $node = shift;

  # Just text => get it
  return $text unless ref $node;  

  # Not a special tag => get its children texts
  my $tag = $node->tag; 
  return get_all_text_in($node) unless $action{$node->tag};

  # Special tag => process it accordingly
  return $action{$tag}->($node);
}