protected void addPositionsInDirection(
      int rowOffset, int columnOffset, Set<Position> positionSet) {
    Position position = this.position.offset(rowOffset, columnOffset);
    while (board.isInsideBounds(position)) {
      if (!board.isEmpty(position)) {
        if (isEnemy(position)) {
          positionSet.add(position);
        }
        break;
      }
      positionSet.add(position);
      position = position.offset(rowOffset, columnOffset);
    }
  }