Function getOrCreateInjectable

packages/core/src/render3/di.ts:457–494

(
  tNode: TDirectiveHostNode | null,
  lView: LView,
  token: ProviderToken<T>,
  flags: InternalInjectFlags = InternalInjectFlags.Default,
  notFoundValue?: any,
)

 * @returns the value from the injector, `null` when not found, or `notFoundValue` if provided
 */
export function getOrCreateInjectable<T>(
  tNode: TDirectiveHostNode | null,
  lView: LView,
  token: ProviderToken<T>,
  flags: InternalInjectFlags = InternalInjectFlags.Default,
  notFoundValue?: any,
): T | null {
  if (tNode !== null) {
    // If the view or any of its ancestors have an embedded
    // view injector, we have to look it up there first.
    if (
      lView[FLAGS] & LViewFlags.HasEmbeddedViewInjector &&
      // The token must be present on the current node injector when the `Self`
      // flag is set, so the lookup on embedded view injector(s) can be skipped.
      !(flags & InternalInjectFlags.Self)
    ) {
      const embeddedInjectorValue = lookupTokenUsingEmbeddedInjector(
        tNode,
        lView,
        token,
        flags,
        NOT_FOUND,
      );
      if (embeddedInjectorValue !== NOT_FOUND) {
        return embeddedInjectorValue;
      }
    }

    // Otherwise try the node injector.
    const value = lookupTokenUsingNodeInjector(tNode, lView, token, flags, NOT_FOUND);
    if (value !== NOT_FOUND) {
      return value;
    }
  }

  // Finally, fall back to the module injector.
  return lookupTokenUsingModuleInjector<T>(lView, token, flags, notFoundValue);
}

/**
 * Returns the value associated to the given token from the node injector.