#
# This software is Copyright 2005 by Elsevier Inc.  You may use it
# under the terms of the license at http://perl.plover.com/hop/LICENSE.txt .
#



###
### make-value-search
###

## Chapter 5 section 3

sub make_dfs_value_search {
  my ($root, $children, $is_interesting, $evaluate) = @_;
  $evaluate = memoize($evaluate);
  my @agenda = $root;
  return Iterator {
    while (@agenda) {
      my $best_node_so_far = 0;
      my $best_node_value = $evaluate->($agenda[0]);
      for (0 .. $#agenda) {
        my $val = $evaluate->($agenda[$_]);
        next unless $val > $best_node_value;
        $best_node_value = $val;
        $best_node_so_far = $_;
      }
      my $node = splice @agenda, $best_node_so_far, 1;
      push @agenda, $children->($node);
      return $node if !$is_interesting || $is_interesting->($node);
    }
    return;
  };
}