nextcloud / server

	 * Only one resolver shall be registered per type. Otherwise a

	 * \OutOfBoundsException has to thrown.

	 */

	public function registerDisplayNameResolver($type, \Closure $closure) {

		if(!is_string($type)) {

			throw new \InvalidArgumentException('String expected.');

		}

		if(isset($this->displayNameResolvers[$type])) {

			throw new \OutOfBoundsException('Displayname resolver for this type already registered');

		}

		$this->displayNameResolvers[$type] = $closure;

	}

	/**

	 * resolves a given ID of a given Type to a display name.

	 * be thrown. It is upon the resolver discretion what to return of the

	 * provided ID is unknown. It must be ensured that a string is returned.

	 */

	public function resolveDisplayName($type, $id) {

		if(!is_string($type)) {

			throw new \InvalidArgumentException('String expected.');

		}

		if(!isset($this->displayNameResolvers[$type])) {

			throw new \OutOfBoundsException('No Displayname resolver for this type registered');

		}

		return (string)$this->displayNameResolvers[$type]($id);

	}

	/**

	 * returns valid, registered entities