How to cross reference?

[Serhioromano]

For instance I have a rule

const fun = createToken({ name: "FUNCTION", pattern: /FUNCTION/ });
const efun = createToken({ name: "END_FUNCTION", pattern: /END_FUNCTION/ });
const variable = createToken({ name: "simbol", pattern: /[a-zA-Z]+[a-zA-Z0-9_]*/ });

$.RULE("function", () => {
    $.CONSUME(fun);
    $.CONSUME(variable, {LABEL: 'function_name'});
    $.CONSUME(efun);
});

Then I have a rule where I can select variable or name of that function

$.RULE("var_declaration", () => {
    $.MANY(() => {
        $.CONSUME(variable, {LABEL: "var_name"});
        $.SUBRULE($.var_type);
    });
});
$.RULE("var_type", () => {
    $.OR([
        { ALT: () => $.CONSUME(variable) }
        // How to add names of functions here?
    ]);
});

I want to add to var_type rule not only any text but also name of the functions created,

[msujew]

Hey @Serhioromano,

a parser by itself is not capable of recognizing or processing cross references. That requires a more involved approach. For the parser all cross references are just symbols/IDs (variable token in your case). A secondary processing step should then translate the variable name to an actual cross reference, using something like a symbol table (something C++ is using).

Shameless self plug: We (TypeFox) have written the Langium framework to simplify building and maintaining languages and language servers in particular. It uses Chevrotain under the hood, but puts a grammar language on top of it, which also includes automatic cross reference resolution.

[Serhioromano]

I have found Langium and have try it in a playground. Go to reference and autocomplete works fine with function names suggestion. Although it was hard to work on playground because it is not informative and when there is an error, I do not see it and sometimes after error even correct code not working you need to refresh the page.

Although I should say I was very impressed with it. I would like to learn how to now build it into my extension, but I did not find clear documentation how to build VS Code Extension after I completed my .langium file.

[msujew]

I would recommend you to start with the getting started page it shows how to use yeoman to set up a vscode extension for your language. There's also some other documentation available on how the grammar language, and other stuff. The framework is still not in a full release yet, but we are working on a lot of new documentation and guides right now.