Function makeDecorator

packages/core/src/util/decorators.ts:47–90

(
  name: string,
  props?: (...args: any[]) => any,
  parentClass?: any,
  additionalProcessing?: (type: Type<T>) => void,
  typeFn?: (type: Type<T>, ...args: any[]) => void,
)

 * @suppress {globalThis}
 */
export function makeDecorator<T>(
  name: string,
  props?: (...args: any[]) => any,
  parentClass?: any,
  additionalProcessing?: (type: Type<T>) => void,
  typeFn?: (type: Type<T>, ...args: any[]) => void,
): {new (...args: any[]): any; (...args: any[]): any; (...args: any[]): (cls: any) => any} {
  return noSideEffects(() => {
    const metaCtor = makeMetadataCtor(props);

    function DecoratorFactory(
      this: unknown | typeof DecoratorFactory,
      ...args: any[]
    ): (cls: Type<T>) => any {
      if (this instanceof DecoratorFactory) {
        metaCtor.call(this, ...args);
        return this as typeof DecoratorFactory;
      }

      const annotationInstance = new (DecoratorFactory as any)(...args);
      return function TypeDecorator(cls: Type<T>) {
        if (typeFn) typeFn(cls, ...args);
        // Use of Object.defineProperty is important since it creates non-enumerable property which
        // prevents the property is copied during subclassing.
        const annotations = cls.hasOwnProperty(ANNOTATIONS)
          ? (cls as any)[ANNOTATIONS]
          : (Object.defineProperty(cls, ANNOTATIONS, {value: []}) as any)[ANNOTATIONS];
        annotations.push(annotationInstance);

        if (additionalProcessing) additionalProcessing(cls);

        return cls;
      };
    }

    if (parentClass) {
      DecoratorFactory.prototype = Object.create(parentClass.prototype);
    }

    DecoratorFactory.prototype.ngMetadataName = name;
    (DecoratorFactory as any).annotationCls = DecoratorFactory;
    return DecoratorFactory as any;
  });
}

function makeMetadataCtor(props?: (...args: any[]) => any): any {
  return function ctor(this: any, ...args: any[]) {