Allow extensions to be able to make requests to the typescript extension's tsserver via commands

extensions/typescript-language-features/package.json

@@ -63,10 +63,11 @@
     "onCommand:javascript.goToProjectConfig",
     "onCommand:typescript.goToProjectConfig",
     "onCommand:typescript.openTsServerLog",
-    "onTaskType:typescript",
+    "onCommand:typescript.tsserverRequest",
     "onCommand:_typescript.configurePlugin",
     "onCommand:_typescript.learnMoreAboutRefactorings",
     "onCommand:typescript.fileReferences",
+    "onTaskType:typescript",
     "onLanguage:jsonc"
   ],
   "main": "./out/extension",

extensions/typescript-language-features/src/commands/commandManager.ts

@@ -8,7 +8,7 @@ import * as vscode from 'vscode';
 export interface Command {
 	readonly id: string;
 
-	execute(...args: any[]): void;
+	execute(...args: any[]): void | any;
 }
 
 export class CommandManager {

extensions/typescript-language-features/src/commands/index.ts

@@ -15,6 +15,7 @@ import { OpenTsServerLogCommand } from './openTsServerLog';
 import { ReloadJavaScriptProjectsCommand, ReloadTypeScriptProjectsCommand } from './reloadProject';
 import { RestartTsServerCommand } from './restartTsServer';
 import { SelectTypeScriptVersionCommand } from './selectTypeScriptVersion';
+import { TSServerRequestCommand } from './tsserverRequests';
 
 export function registerBaseCommands(
 	commandManager: CommandManager,
@@ -31,4 +32,5 @@ export function registerBaseCommands(
 	commandManager.register(new JavaScriptGoToProjectConfigCommand(activeJsTsEditorTracker, lazyClientHost));
 	commandManager.register(new ConfigurePluginCommand(pluginManager));
 	commandManager.register(new LearnMoreAboutRefactoringsCommand());
+	commandManager.register(new TSServerRequestCommand(lazyClientHost));
 }

extensions/typescript-language-features/src/commands/tsserverRequests.ts

@@ -0,0 +1,43 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { TypeScriptRequests } from '../typescriptService';
+import TypeScriptServiceClientHost from '../typeScriptServiceClientHost';
+import { nulToken } from '../utils/cancellation';
+import { Lazy } from '../utils/lazy';
+import { Command } from './commandManager';
+
+export class TSServerRequestCommand implements Command {
+	public readonly id = 'typescript.tsserverRequest';
+
+	public constructor(
+		private readonly lazyClientHost: Lazy<TypeScriptServiceClientHost>
+	) { }
+
+	public execute(requestID: keyof TypeScriptRequests, args?: any, config?: any) {
+		// A cancellation token cannot be passed through the command infrastructure
+		const token = nulToken;
+
+		// The list can be found in the TypeScript compiler as `const enum CommandTypes`,
+		// to avoid extensions making calls which could affect the internal tsserver state
+		// these are only read-y sorts of commands
+		const allowList = [
+			// Seeing the JS/DTS output for a file
+			'emit-output',
+			// Grabbing a file's diagnostics
+			'semanticDiagnosticsSync',
+			'syntacticDiagnosticsSync',
+			'suggestionDiagnosticsSync',
+			// Introspecting code at a position
+			'quickinfo',
+			'quickinfo-full',
+			'completionInfo'
+		];
+
+		if (!allowList.includes(requestID)) { return; }
+		return this.lazyClientHost.value.serviceClient.execute(requestID, args, token, config);
+	}
+}
+