class Sinatra::Response

def body=(value)
  value = value.body while Rack::Response === value
  @body = String === value ? [value.to_str] : value
end

def calculate_content_length?
  headers['Content-Type'] && !headers['Content-Length'] && (Array === body)
end

def drop_body?
  DROP_BODY_RESPONSES.include?(status)
end

def drop_content_info?
  informational? || drop_body?
end

def each
  block_given? ? super : enum_for(:each)
end

def finish
  result = body
  if drop_content_info?
    headers.delete 'Content-Length'
    headers.delete 'Content-Type'
  end
  if drop_body?
    close
    result = []
  end
  if calculate_content_length?
    # if some other code has already set Content-Length, don't muck with it
    # currently, this would be the static file-handler
    headers['Content-Length'] = body.map(&:bytesize).reduce(0, :+).to_s
  end
  [status, headers, result]
end