When/how are file event handlers called?

[kristianmandrup]

I can't figure out how these event handlers fit into the pipeline?
I've be trying to customise aster to not be hardcoded to only work with files.
I'd like to make my own custom runner, but not sure where I should call/trigger equivalent events like onComplete etc. Is it the Observable created for each read file?

Please advice. Thanks!

[kristianmandrup]

Ah, I think I got confused about the function names. I'm complete newbie to Observable and Rx.
So when you create an Observable, you pass 3 functions in this order: successHandler, errorHandler, onCompleteHandler. So the question then becomes, what is the files` argument exactly? any Observable as well, since it can be subscribed on? hence I guess it's a stream of events, such as an array of files being processed one at a time... makes sense!
Cheers :)

[RReverser]

They're just file ASTs (wrappers around ESTree Program node).