Update extension.ts

package.json

@@ -3,7 +3,7 @@
 	"displayName": "vscode-erg",
 	"description": "Erg language support for Visual Studio Code",
 	"publisher": "erg-lang",
-	"version": "0.1.6",
+	"version": "0.1.7",
 	"engines": {
 		"vscode": "^1.70.0"
 	},

src/extension.ts

@@ -1,28 +1,42 @@
 // import { LanguageClientOptions } from "vscode-languageclient";
 import { ExtensionContext, window } from "vscode";
 import { LanguageClient, ServerOptions } from "vscode-languageclient/node";
+import { spawnSync } from "child_process";
 
 let client: LanguageClient | undefined;
 
+export async function activate_els(context: ExtensionContext) {
+    let serverOptions;
+    let result = spawnSync("erg", ["--build-features"]);
+    if (result.stdout.toString().includes("els")) {
+        serverOptions = {
+            command: "erg",
+            args: ["--language-server"]
+        };
+    } else {
+        serverOptions = {
+            command: "els",
+            args: []
+        };
+    }
+    const clientOptions = {
+        documentSelector: [
+            {
+                scheme: "file",
+                language: "erg",
+            }
+        ],
+    };
+    client = new LanguageClient("els", serverOptions, clientOptions);
+    context.subscriptions.push(client.start());
+}
+
 export async function activate(context: ExtensionContext) {
-	try {
-		const serverOptions = {
-			command: "els",
-			args: [],
-		}; // satisfies ServerOptions;
-		const clientOptions = {
-			documentSelector: [
-				{
-					scheme: "file",
-					language: "erg",
-				},
-			],
-		}; // satisfies LanguageClientOptions;
-		client = new LanguageClient("els", serverOptions, clientOptions);
-		context.subscriptions.push(client.start());
-	} catch (e) {
-		window.showErrorMessage("failed to start els.");
-	}
+    try {
+        activate_els(context);
+    } catch (e) {
+        window.showErrorMessage("Failed to start ELS (Erg Language Server). Please make sure you have erg (built with `els` feature) or els installed.");
+    }
 }
 
 export function deactivate() {