###
### make-dfs-search
###

## Chapter 5 section 3

use Iterator_Utils 'Iterator';

sub make_dfs_search {
  my ($root, $children, $is_interesting) = @_;
  my @agenda = $root;
  return Iterator {
    while (@agenda) {
      my $node = pop @agenda;
      push @agenda, $children->($node);
      return $node if !$is_interesting || $is_interesting->($node);
    }
    return;
  };
}       

1;