is there a way to easily import "langium-grammar.langium"; ?

[jdeantoni]

Hi,

I would like to propose a language that references ParserRules (or AbstractRules, to be defined later).
I tried naively to do an import "langium-grammar.langium"; in my grammar but this does not compile:
/home/jdeanton/boulot/enseignements/L3IA_langageEtCompil/testLangium/sos/node_modules/langium/lib/utils/ast-util.js:85 while (node.$container) {
^

TypeError: Cannot read properties of undefined (reading '$container')

I guess this is because I'm not telling where is the langium grammar exactly ? I'm not sure if there exist a registry or something similar from which I could import the grammar.

Additionally, once I will be able to do so, I would like in my language to import a specific langium grammar (e.g. import "hello.langium". I used to use importURI in Xtext. Is there something similar ? Should I load myself the file in the scope provider and provision the ParserRules instances in the local scope manually ?

Thanks in advance !

[msujew]

Hey @jdeantoni,

I'm a bit suprised by Langium spitting out an internal error for this (it should show a validation message instead). In theory you should be able to reference it by using something like import "../node_modules/langium/src/language-server/langium-grammar"; (with as many .. as needed for your directory structure). The language server might complain until you remove the node_modules from the ignore pattern of the langium vscode settings.

Note that compared to Xtext, this effectively only copies the grammar rules and the interfaces/types and does not create actual relationships between the original objects of the language. You can of course still parse .langium files using your project and reference these elements in your language, but there's no global storage where Langium elements are exported to so they're available for referencing.

Should I load myself the file in the scope provider and provision the ParserRules instances in the local scope manually ?

In theory it should be loaded together as part of your language server initialization and then scoped to the import. We do it similarly in our own scope provider.

[jdeantoni]

Thanks @msujew, that was very helpfull. Just a quick note, the link to be used is : import "../../node_modules/langium/src/grammar/langium-grammar"

With this import, I'm able to write down correctly my grammar. However, I was not able to correctly set up my scope provider by looking at yours. I'm able to retrieve the URI I want to load int the function but then some magic appeared in your scope provider since the elements seems to be already in the indexManager while mines are not there. Any idea why ? I did not understand how it was managed.

Thanks !

[jdeantoni]

yes, sure, thanks. Here it is:
https://github.com/jdeantoni/SoS.lang

[msujew]

I'm not sure what's wrong there, it works for me right out of the box ¯\_(ツ)_/¯

[jdeantoni]

OK thanks so I guess this is some mess on my side. I'll check that ! thanks !

[jdeantoni]

oh ! sorry !! it was a mess in my folders and workspaces ! Sorry for that

[msujew]

All good. I'm glad things have worked out :)