Function resolveThenable

packages/react/src/ReactChildren.js:86–144

(thenable: Thenable<T>)

}

function resolveThenable<T>(thenable: Thenable<T>): T {
  switch (thenable.status) {
    case class="st">'fulfilled': {
      const fulfilledValue: T = thenable.value;
      return fulfilledValue;
    }
    case class="st">'rejected': {
      const rejectedError = thenable.reason;
      throw rejectedError;
    }
    default: {
      if (typeof thenable.status === class="st">'string') {
        class="cm">// Only instrument the thenable if the status if not defined. If
        class="cm">// itclass="st">'s defined, but an unknown value, assume it's been instrumented by
        class="cm">// some custom userspace implementation. We treat it as class="st">"pending".
        class="cm">// Attach a dummy listener, to ensure that any lazy initialization can
        class="cm">// happen. Flight lazily parses JSON when the value is actually awaited.
        thenable.then(noop, noop);
      } else {
        class="cm">// This is an uncached thenable that we haven't seen before.

        class="cm">// TODO: Detect infinite ping loops caused by uncached promises.

        const pendingThenable: PendingThenable<T> = (thenable: any);
        pendingThenable.status = class="st">'pending';
        pendingThenable.then(
          fulfilledValue => {
            if (thenable.status === class="st">'pending') {
              const fulfilledThenable: FulfilledThenable<T> = (thenable: any);
              fulfilledThenable.status = class="st">'fulfilled';
              fulfilledThenable.value = fulfilledValue;
            }
          },
          (error: mixed) => {
            if (thenable.status === class="st">'pending') {
              const rejectedThenable: RejectedThenable<T> = (thenable: any);
              rejectedThenable.status = class="st">'rejected';
              rejectedThenable.reason = error;
            }
          },
        );
      }

      class="cm">// Check one more time in case the thenable resolved synchronously.
      switch ((thenable: Thenable<T>).status) {
        case class="st">'fulfilled': {
          const fulfilledThenable: FulfilledThenable<T> = (thenable: any);
          return fulfilledThenable.value;
        }
        case class="st">'rejected': {
          const rejectedThenable: RejectedThenable<T> = (thenable: any);
          const rejectedError = rejectedThenable.reason;
          throw rejectedError;
        }
      }
    }
  }
  throw thenable;