Plugin_Loader::autoload( string $class )

	public function autoload( $class ) {
		if ( 0 !== strpos( $class, __NAMESPACE__ ) ) {
			return;
		}

		$class_to_load = $class;

		$filename = strtolower(
			preg_replace(
				[ '/^' . __NAMESPACE__ . '\\\/', '/([a-z])([A-Z])/', '/_/', '/\\\/' ],
				[ '', '$1-$2', '-', DIRECTORY_SEPARATOR ],
				$class_to_load
			)
		);

		$file = BSF_UTM_ANALYTICS_DIR . $filename . '.php';

		// if the file readable, include it.
		if ( is_readable( $file ) ) {
			require_once $file;
		}
	}