public function use_default_processor( callable $processor = null ) {

		static $done = FALSE;
		if ( $done ) {
			return $this;
		}

		$done = TRUE;

		add_action(
			ProcessorsRegistry::ACTION_REGISTER,
			function ( ProcessorsRegistry $registry ) use ($processor) {
				$processor or $processor = new WpContextProcessor();

				$registry->add_processor( $processor, ProcessorsRegistry::DEFAULT_NAME );
			}
		);

		return $this;
	}