protected function parseSortDefinition($definition) {
		$definition = trim($definition);
		$spacePos   = strrpos($definition, ' ');
		
		if ($spacePos === false) {
			return [$definition, SORT_ASC];
		}
		
		$property  = substr($definition, 0, $spacePos);
		$direction = substr($definition, $spacePos);
		$direction = strtolower(ltrim($direction));

		if ($direction === self::SORT_ASC) {
			return [$property, SORT_ASC];
		}
		
		if ($direction === self::SORT_DESC) {
			return [$property, SORT_DESC];
		}
		
		throw new Exception('Unknown sort direction: "' . $direction . '"');
	}