File-based scoping

[drhagen]

Are there any examples of scoping names to the file? Neither of scoping guides does this. I don't want to do gimme teh codez, but this is a common enough language feature that I am guessing someone out there has a DSL with file-based scoping already.

[cdietrich]

What do you mean by that? No references to other files?

[drhagen]

Sure, for simplicity, let's assume none at all. A variable foo can reference something defined in the current file, but does not see foo declared in a different file.

[cdietrich]

langium/packages/langium/src/references/scope-provider.ts

Line 101 in f3321b6

return this.globalScopeCache.get(referenceType, () => new MapScope(this.indexManager.allElements(referenceType)));

override and return empty

[drhagen]

Overriding getGlobalScope and returning an empty scope works. Here's the minimal code for modifying the Hello World project to enforce file-scoping.

Add file hello-world-scope-provider.ts with contents:

import type { Scope } from 'langium';
import { EMPTY_SCOPE } from 'langium';
import { DefaultScopeProvider } from 'langium';

/**
 * Scope provider that restricts scope to a single file
 */
export class HelloWorldScopeProvider extends DefaultScopeProvider {
    protected override getGlobalScope(referenceType: string): Scope {
        return EMPTY_SCOPE;
    }
}

Like in the other examples modify HelloWorldModule in hello-world-module.ts to inject this scope provider:

// ...
export const HelloWorldModule: Module<HelloWorldServices, PartialLangiumServices & HelloWorldAddedServices> = {
    references: {
        ScopeProvider: (services) => new HelloWorldScopeProvider(services)
    },

// ...
};
// ...