Function resolvePromise

packages/zone.js/lib/common/promise.ts:137–249

(
      promise: ZoneAwarePromise<any>,
      state: boolean,
      value: any,
    )

    // Promise Resolution
    function resolvePromise(
      promise: ZoneAwarePromise<any>,
      state: boolean,
      value: any,
    ): ZoneAwarePromise<any> {
      const onceWrapper = once();
      if (promise === value) {
        throw new TypeError(TYPE_ERROR);
      }
      if ((promise as any)[symbolState] === UNRESOLVED) {
        // should only get value.then once based on promise spec.
        let then: any = null;
        try {
          if (typeof value === 'object' || typeof value === 'function') {
            then = value && value.then;
          }
        } catch (err) {
          onceWrapper(() => {
            resolvePromise(promise, false, err);
          })();
          return promise;
        }
        // if (value instanceof ZoneAwarePromise) {
        if (
          state !== REJECTED &&
          value instanceof ZoneAwarePromise &&
          value.hasOwnProperty(symbolState) &&
          value.hasOwnProperty(symbolValue) &&
          (value as any)[symbolState] !== UNRESOLVED
        ) {
          clearRejectedNoCatch(value);
          resolvePromise(promise, (value as any)[symbolState], (value as any)[symbolValue]);
        } else if (state !== REJECTED && typeof then === 'function') {
          try {
            then.call(
              value,
              onceWrapper(makeResolver(promise, state)),
              onceWrapper(makeResolver(promise, false)),
            );
          } catch (err) {
            onceWrapper(() => {
              resolvePromise(promise, false, err);
            })();
          }
        } else {
          (promise as any)[symbolState] = state;
          const queue = (promise as any)[symbolValue];
          (promise as any)[symbolValue] = value;

          if ((promise as any)[symbolFinally] === symbolFinally) {
            // the promise is generated by Promise.prototype.finally
            if (state === RESOLVED) {
              // the state is resolved, should ignore the value
              // and use parent promise value
              (promise as any)[symbolState] = (promise as any)[symbolParentPromiseState];
              (promise as any)[symbolValue] = (promise as any)[symbolParentPromiseValue];
            }
          }