Is it possible to use SplEnum in php 5.2.6?

I tried to use class :

abstract class my_abstractEnum extends SplEnum {
...
}

and

class my_categoryEnum extends my_abstractEnum {
...
}

and I have :

Fatal error: Class 'SplEnum' not found

I work on PHP 5.2.6. SplEnum is for php > 5.3 ? I don't see so in the documentation ...