React DOM legacy server impl

一、作用

二、渲染为字符串实现

备注

• createResumableState() 由 ReactFizzConfigDOMLegacy#createResumableState 实现
• createRequest() 由 ReactFizzServer#createRequest 实现
• createRenderState() 由 ReactFizzConfigDOMLegacy#createRenderState 实现
• createRootFormatContext() 由 ReactFizzConfigDOMLegacy#createRootFormatContext 实现
• startWork() 由 ReactFizzServer#startWork 实现
• abort() 由 ReactFizzServer#abort 实现
• startFlowing() 由 ReactFizzServer#startFlowing 实现

function renderToStringImpl(
  children: ReactNodeList,
  options: void | ServerOptions,
  generateStaticMarkup: boolean,
  abortReason: string,
): string {
  let didFatal = false;
  let fatalError = null;
  let result = '';
  const destination = {
    push(chunk) {
      if (chunk !== null) {
        result += chunk;
      }
      return true;
    },
    destroy(error) {
      didFatal = true;
      fatalError = error;
    },
  };

  let readyToStream = false;
  function onShellReady() {
    readyToStream = true;
  }
  const resumableState = createResumableState(
    options ? options.identifierPrefix : undefined,
    undefined,
  );
  const request = createRequest(
    children,
    resumableState,
    createRenderState(resumableState, generateStaticMarkup),
    createRootFormatContext(),
    Infinity,
    onError,
    undefined,
    onShellReady,
    undefined,
    undefined,
    undefined,
  );
  startWork(request);
  // If anything suspended and is still pending, we'll abort it before writing.
  // 如果有任何挂起的内容仍在等待，我们将在写入之前中止它。
  // That way we write only client-rendered boundaries from the start.
  // 这样我们从一开始就只写入客户端渲染的边界。
  abort(request, abortReason);
  startFlowing(request, destination);
  if (didFatal && fatalError !== abortReason) {
    throw fatalError;
  }

  if (!readyToStream) {
    // Note: This error message is the one we use on the client. It doesn't
    // really make sense here. But this is the legacy server renderer, anyway.
    // 注意：此错误信息是我们在客户端使用的。在这里它并不真正有意义。但无论如何，这是传统的服务器渲染器。
    // We're going to delete it soon.
    // 我们很快会删除它。
    throw new Error(
      'A component suspended while responding to synchronous input. This ' +
        'will cause the UI to be replaced with a loading indicator. To fix, ' +
        'updates that suspend should be wrapped with startTransition.',
    );
  }

  return result;
}

三、工具

1. 出错时

function onError() {
  // Non-fatal errors are ignored.
  // 非致命错误会被忽略。
}

四、类型

1. 服务器选项

type ServerOptions = {
  identifierPrefix?: string;
};

五、转导

• 从 ReactVersion 转导了 ReactVersion as version