How well are Parameterized Rules supported in langium

[cdietrich]

Hi, how well are Parameterized Rules supported in langium?
i observe that it seems to work on parser side but not on completion provider side

working

entry Model:
    (ds+=Thing)*;

VirtualField:
    VirtualFieldCommonParts ('=' (expression=INT | 'formula' formula=STRING))?;

PureVirtualField infers VirtualField:
    VirtualFieldCommonParts
;

fragment VirtualFieldCommonParts*:
    'virtual' 'field' name=ID ':' type=ID
;


Thing:
    type=("struct" | "list") name=ID '{' 
        ((data=ID (content+=VirtualField)*) |
        (content+=PureVirtualField)*)
    '}';

not working (= is proposed in both cases)

entry Model:
    (ds+=Thing)*;

VirtualField<wi>:
    'virtual' 'field' name=ID ':' type=ID (<wi>'=' (expression=INT | 'formula' formula=STRING))?;

Thing:
    type=("struct" | "list") name=ID '{' 
        ((data=ID (content+=VirtualField<true>)*) |
        (content+=VirtualField<false>)*)
    '}';

both with

export class DemoCompletionProvider extends DefaultCompletionProvider {
    protected override filterKeyword(context: CompletionContext, keyword: grammar.Keyword) {
        return true;
    }
} 

test model

struct x {
    xxxxx
    virtual field a :x  |
    virtual field b : y 

}

list y {
    virtual field c : d |
}

[msujew]

Hey @cdietrich,

it's exactly as you describe. They are supported on the parsing layer (even in the completion parser), but the information about rule parameters isn't returned by the completion parser (yet). Consequently, the completion provider isn't aware of which parameters to apply when identifying the follow-elements.