Value Converters and errors.

[cdietrich]

Hi, is there a way to validate the value of a datatype rule inside a valueconverter?
throwing an error does not seem to get reported?
if the value converter is not the correct place(unlike xtext)
what is the proper place to validate datatype rules?

[msujew]

Hey @cdietrich,

I'm not entirely sure what the result is you're looking for. Generally, the value converter is not expected to throw, and there is no try-catch surrounding its caller side (meaning that you likely break the parsing process by throwing). Instead, it should return an invalid value, like NaN or similar. Then you can validate on the validator wrt to the expected value.

[cdietrich]

So if we have a JSON_VALUE : STRING we need to call the same semantic validation on all ast nodes using it

[msujew]

As of now, yes. There are only 4 kinds of diagnostics being produced/respected by Langium (at least by default).

[cdietrich]

Thx. Will check if I can make it generic traversing from root ast or cst