Support for Xtext enum

[brsanthu]

We had a language in Xtext. We are migrating into Langium.

Xtext had concept of enum values like this.

enum ForLiterals:
    update
    | view
    | reference
;

I haven't seen any mention of this in Langium grammar.

1. Is there an equivalent concept?
2. Or support for it is not there yet and will be added?

[Yokozuna59]

I'd recommend you read this article: https://www.typefox.io/blog/xtext-to-langium/ and this discussion: #521.

But answering your question using the article approach, then it would be something like this:

Xtext:

enum ForLiterals: update | view | reference;

Langium:

type ForLiterals = 'update' | 'view' | 'reference';
ForLiterals returns ForLiterals:
	ForLiterals_Update | ForLiterals_View | ForLiterals_Reference
;
ForLiterals_Update returns string: 'update';
ForLiterals_View returns string: 'view';
ForLiterals_Reference returns string: 'reference';

[msujew]

I think you can shorten this to just:

ForLiterals returns string:
    'update'
    | 'view'
    | 'reference'
;

[brsanthu]

Thank you for that great reference. We could convert our old xtext based grammar into Langium. There were couple of issues. The ML and SL comments were not working when we migrated. We had to redo that part.

Other than that we haven't seen other issues. Will keep an eye and post about any issues here.