Function createModelSignal

packages/core/src/authoring/model/model_signal.ts:64–107

(initialValue: T, opts?: ModelOptions)

 * @param options Additional options for the model.
 */
export function createModelSignal<T>(initialValue: T, opts?: ModelOptions): ModelSignal<T> {
  const node: InputSignalNode<T, T> = Object.create(INPUT_SIGNAL_NODE);
  const emitterRef = new OutputEmitterRef<T>();

  node.value = initialValue;

  function getter(): T {
    producerAccessed(node);
    assertModelSet(node.value);
    return node.value;
  }

  getter[SIGNAL] = node;
  getter.asReadonly = signalAsReadonlyFn.bind(getter as any) as () => Signal<T>;

  // TODO: Should we throw an error when updating a destroyed model?
  getter.set = (newValue: T) => {
    if (!node.equal(node.value, newValue)) {
      signalSetFn(node, newValue);
      emitterRef.emit(newValue);
    }
  };

  getter.update = (updateFn: (value: T) => T) => {
    assertModelSet(node.value);
    getter.set(updateFn(node.value));
  };

  getter.subscribe = emitterRef.subscribe.bind(emitterRef);
  getter.destroyRef = emitterRef.destroyRef;

  if (ngDevMode) {
    getter.toString = () => `[Model Signal: ${getter()}]`;
    node.debugName = opts?.debugName;
  }

  return getter as typeof getter &
    Pick<
      ModelSignal<T>,
      | typeof ɵINPUT_SIGNAL_BRAND_READ_TYPE
      | typeof ɵINPUT_SIGNAL_BRAND_WRITE_TYPE
      | typeof ɵWRITABLE_SIGNAL
    >;
}

/** Asserts that a model's value is set. */
function assertModelSet(value: unknown): void {