extract common logic to abstract generator

[devmsh]

By introducing a property for $new_instance, we can easily extract the duplicated code between generators and pull them up to an abstract generator class.

Even If we need to customize any of the extracted methods in the future, we can override them so I change the visibility of these methods to protected.

Hope you will find this useful.

I will start working on the Tree class as we discussed before, and submit a PR tonight 👍

[jasonmccreary]

I don't understand the purpose of $new_instance. Also, if only statement generators extend from this, I'd prefer to make the abstract class more specific, i.e. StatementGenerator

[devmsh]

@jasonmccreary the $new_instance only use to customize the constructor doc block text, I did not see a big advantage from it, but I tried to refactor the code without any breaking changes.

For the 2nd point, the Generator currently holds the common constructor related logic, but I think it may hold different peace of logic in the next refactoring and some of them may be helpful for other generators?

[jasonmccreary]

That's fine to leave $new_instance, I'll remove it afterwards.

I understand. However, I am going to change this to StatementGenerator. It in turn can extend an abstract Generator class in a future refactor if necessary.

[devmsh]

Done 👍

[jasonmccreary]

Cool. Thanks. Will review and merge tomorrow.

[jasonmccreary]

@devmsh what was the point of the static here? It's causing issues with tests in PHP 8.1.