class Regexp::Parser

def free_space(token)
  case token.token
  when :comment
    node << Comment.new(token, active_opts)
  when :whitespace
    if node.last.is_a?(WhiteSpace)
      node.last.merge(WhiteSpace.new(token, active_opts))
    else
      node << WhiteSpace.new(token, active_opts)
    end
  else
    raise UnknownTokenError.new('FreeSpace', token)
  end
end