React 共享内部客户端

type onStartTransitionFinish = (transition: Transition, mixed: mixed) => void;
type onStartGestureTransitionFinish = (
  transition: Transition,
  gestureProvider: GestureProvider,
  gestureOptions?: GestureOptions,
) => () => void;

export type SharedStateClient = {
  H: null | Dispatcher; // ReactCurrentDispatcher for Hooks
  A: null | AsyncDispatcher; // ReactCurrentCache for Cache
  T: null | Transition; // ReactCurrentBatchConfig for Transitions
  S: null | onStartTransitionFinish;
  G: null | onStartGestureTransitionFinish;

  // DEV-only

  // ReactCurrentActQueue
  actQueue: null | Array<RendererTask>;

  // When zero this means we're outside an async startTransition.
  asyncTransitions: number;

  // Used to reproduce behavior of `batchedUpdates` in legacy mode.
  isBatchingLegacy: boolean;
  didScheduleLegacyUpdate: boolean;

  // Tracks whether something called `use` during the current batch of work.
  // Determines whether we should yield to microtasks to unwrap already resolved
  // promises without suspending.
  //
  // 跟踪当前工作批次中是否调用了名为 `use` 的东西。 决定我们是否应该让出给微任务，以便在不挂起的
  // 情况下获取已解析的 promise 的结果。
  didUsePromise: boolean;

  // Track first uncaught error within this act
  // 跟踪此行为中的第一个未捕获错误
  thrownErrors: Array<mixed>;

  // ReactDebugCurrentFrame
  // React 调试当前帧
  getCurrentStack: null | (() => string);

  // ReactOwnerStackReset
  // React 所有者堆栈重置
  recentlyCreatedOwnerStacks: 0;
};

export type RendererTask = (boolean) => RendererTask | null;

const ReactSharedInternals: SharedStateClient = {
  H: null,
  A: null,
  T: null,
  S: null,
} as any;
if (enableGestureTransition) {
  ReactSharedInternals.G = null;
}

if (__DEV__) {
  ReactSharedInternals.actQueue = null;
  ReactSharedInternals.asyncTransitions = 0;
  ReactSharedInternals.isBatchingLegacy = false;
  ReactSharedInternals.didScheduleLegacyUpdate = false;
  ReactSharedInternals.didUsePromise = false;
  ReactSharedInternals.thrownErrors = [];
  // Stack implementation injected by the current renderer.
  // 当前渲染器注入的堆栈实现。
  ReactSharedInternals.getCurrentStack = null as null | (() => string);
  ReactSharedInternals.recentlyCreatedOwnerStacks = 0;
}

export default ReactSharedInternals;