import { checkArgumentType } from "../errors";

export class Lazy<T> {
  private _value?: T;
  private _valueFactory?: () => T;
  public constructor(valueFactory: () => T) {
    checkArgumentType(0, "valueFactory", valueFactory, "function");
    this._valueFactory = valueFactory;
  }
  public get valueCreated(): boolean {
    return this._valueFactory == null;
  }
  public get value(): T {
    if (this._valueFactory != null) {
      // Detach the value factory as we won't be needing it anymore.
      this._value = this._valueFactory();
      delete this._valueFactory;
    }
    return this._value!;
  }
}