protected function findFormatClass($possibleFormat = null, $default = null)
	{
		static $mimeTypes = null;
		
		if ($possibleFormat !== null)
		{
			$className = __NAMESPACE__.'\\Format\\'.ucfirst($possibleFormat);
			
			if (class_exists($className))
			{
				return $className;
			}
		}
		
		if ( ! $mimeTypes)
		{
			$mimeTypes = new MimeTypes();
		}
		
		$extensions = $mimeTypes->getAllExtensions($this->getMimeType());
		$extensions[] = pathinfo($this->getFilePath(), PATHINFO_EXTENSION);
		
		foreach ($extensions as $extension)
		{
			$classString = __NAMESPACE__.'\\Format\\'.ucfirst($extension);
			
			if (class_exists($classString))
			{
				return $classString;
			}
		}
		
		return $default;
	}