Class Binding

packages/context/src/binding.ts:348–1083

 * corresponding value getter.
 */
export class Binding<T = BoundValue> extends EventEmitter {
  /**
   * Key of the binding
   */
  public readonly key: string;

  /**
   * Map for tag name/value pairs
   */
  public readonly tagMap: TagMap = {};

  private _scope?: BindingScope;
  /**
   * Scope of the binding to control how the value is cached/shared
   */
  public get scope(): BindingScope {
    // Default to TRANSIENT if not set
    return this._scope ?? BindingScope.TRANSIENT;
  }

  /**
   * Type of the binding value getter
   */
  public get type(): BindingType | undefined {
    return this._source?.type;
  }

  private _cache: WeakMap<Context, ValueOrPromise<T>>;
  private _getValue?: ValueFactory<T>;

  /**
   * The original source value received from `to`, `toClass`, `toDynamicValue`,
   * `toProvider`, or `toAlias`.
   */
  private _source?: BindingSource<T>;

  public get source() {
    return this._source;
  }

  /**
   * For bindings bound via `toClass()`, this property contains the constructor
   * function of the class
   */
  public get valueConstructor(): Constructor<T> | undefined {
    return this._source?.type === BindingType.CLASS
      ? this._source?.value
      : undefined;
  }

  /**
   * For bindings bound via `toProvider()`, this property contains the
   * constructor function of the provider class
   */
  public get providerConstructor(): Constructor<Provider<T>> | undefined {
    return this._source?.type === BindingType.PROVIDER
      ? this._source?.value
      : undefined;