class Foobara::LruCache

def move_node_to_front(node)
  return if node == @head
  prev_node = node.prev
  next_node = node.next
  if node == @tail
    @tail = prev_node
    @tail.next = nil
  else
    prev_node.next = next_node
    next_node.prev = prev_node
  end
  @head.prev = node
  node.next = @head
  node.prev = nil
  @head = node
end