Expose workspace folders via a readonly getter (#1679)

packages/langium/src/workspace/workspace-manager.ts

@@ -35,6 +35,12 @@ export interface WorkspaceManager {
      */
     readonly ready: Promise<void>;
 
+    /**
+     * The workspace folders of the current workspace.
+     * Available only after the `ready` promise resolves.
+     */
+    get workspaceFolders(): readonly WorkspaceFolder[] | undefined;
+
     /**
      * When used in a language server context, this method is called when the server receives
      * the `initialize` request.
@@ -85,6 +91,10 @@ export class DefaultWorkspaceManager implements WorkspaceManager {
         return this._ready.promise;
     }
 
+    get workspaceFolders(): readonly WorkspaceFolder[] | undefined {
+        return this.folders;
+    }
+
     initialize(params: InitializeParams): void {
         this.folders = params.workspaceFolders ?? undefined;
     }