Question

I m using Xtext to define my DSL. Xtext generates a parser that lets me traverse the EMF model of my input DSL. I d like to translate this EMF model into some other tree. To do this translation, I need to traverse the tree. But, I couldn t find a visitor class for the EMF model generated by Xtext. The closest thing that I ve found is a Switch class that visits a single node. I can traverse the EMF model myself and invoke the Switch class on each node that I visit. But, I wonder if there exists a visitor functionality in Xtext that implements the model traversal.

Answer 1

If you consider this thread, Switch (used here for instance) is pretty much the official visitor pattern for XText.
You also have the custom Validation process:

The purpose of the AbstractDeclarativeValidator is to allow you to write constraints in a declarative way – as the class name already suggests.
That is instead of writing exhaustive if-else constructs or extending the generated EMF switch you just have to add the @Check annotation to any method and it will be invoked automatically when validation takes place.

That may be not exactly what you need, though.

Answer 2

I guess EcoreUtil.getAllProperContents(Resource, false) might be what you are looking for. You ll get a TreeIterator that will traverse the contents of the resource. Pass the result of iter.next() into a Switch and perform the transformation logic depending on the element type.

Answer 3

Hmm, is it not sufficient to use EMF API? If you want to transform the model, is using some of the transformation langauges like Xtend not possible?

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