Launch Yeoman Generator in separate thread

package.json

@@ -34,7 +34,7 @@
     "theiaPlugin": "latest"
   },
   "theiaPlugin": {
-    "backend": "lib/theia-yeoman-plugin-backend-plugin.js"
+    "backend": "lib/theia-yeoman-backend-plugin.js"
   },
   "dependencies": {
     "yeoman-environment": "2.3.0"

src/theia-yeoman-backend-plugin.ts

@@ -0,0 +1,38 @@
+/*********************************************************************
+* Copyright (c) 2018 Red Hat, Inc.
+*
+* This program and the accompanying materials are made
+* available under the terms of the Eclipse Public License 2.0
+* which is available at https://www.eclipse.org/legal/epl-2.0/
+*
+* SPDX-License-Identifier: EPL-2.0
+**********************************************************************/
+
+import * as theia from '@theia/plugin';
+
+import { YeomanProcessAdapter } from './yeoman-process-adapter';
+
+/**
+ * Entry point of the plug-in.
+ * Once starting the plug-in, register a command to start Yeoman wizard.
+ */
+export function start(context: theia.PluginContext) {
+    const yeomanWizardCommand = {
+        id: 'theia-yeoman-plugin-wizard',
+        label: "Yeoman Wizard"
+    };
+
+    theia.commands.registerCommand(yeomanWizardCommand, (...args: any[]) => {
+        showWizard(context);
+    });
+}
+
+let yeoman: YeomanProcessAdapter | undefined;
+
+function showWizard(context: theia.PluginContext) {
+    if (yeoman) {
+        yeoman.destroy();
+    }
+
+    yeoman = new YeomanProcessAdapter((context as any).extensionPath);
+}