# -*- mode: cperl6; -*-

# 2011 Perl 6 Coding Contest
# Edgar Gonzàlez i Pellicer

# Positions
module Position;


# Position pair
class PosPair is export {
  has Int $.i;
  has Int $.j;


  # Next
  method succ() {
    if $.j == $.i {
      return PosPair.new(i => $.i + 1, j => 0);
    }
    else {
      return PosPair.new(i => $.i, j => $.j + 1);
    }
  }


  # Conversion to numeric
  method Numeric() {
    return $.i * ($.i + 1) / 2 + $.j;
  }
}


# Position pair at the start of a container
sub start($) is export {
  return PosPair.new(i => 0, j => 0);
}


# Position pair at the end of a container
sub end($container) is export {
  return PosPair.new(i => $container.elems - 1,
		     j => $container.elems - 1);
}