Simple completion example

analyzer/src/lib.rs

@@ -10,7 +10,19 @@ struct Backend {
 #[tower_lsp::async_trait]
 impl LanguageServer for Backend {
     async fn initialize(&self, _: InitializeParams) -> Result<InitializeResult> {
-        Ok(InitializeResult::default())
+        let mut res = InitializeResult::default();
+
+        res.capabilities.completion_provider = Some(CompletionOptions {
+            resolve_provider: None,
+            trigger_characters: None,
+            all_commit_characters: None,
+            work_done_progress_options: WorkDoneProgressOptions {
+                work_done_progress: None,
+            },
+            completion_item: None,
+        });
+
+        Ok(res)
     }
 
     async fn initialized(&self, _: InitializedParams) {
@@ -19,6 +31,16 @@ impl LanguageServer for Backend {
             .await;
     }
 
+    async fn completion(&self, params: CompletionParams) -> Result<Option<CompletionResponse>> {
+        self.client
+            .log_message(MessageType::INFO, "getting completion")
+            .await;
+
+        Ok(Some(CompletionResponse::Array(vec![
+            CompletionItem::new_simple("new".to_string(), "The new keyword".to_string()),
+        ])))
+    }
+
     async fn shutdown(&self) -> Result<()> {
         Ok(())
     }

src/main.mist

@@ -10,6 +10,7 @@ void main() {
 
     if (args.len() < 2) {
         print_usage();
+        
         process::exit(1);
     }