Add in-memory strict language server (#67)

* Add in-memory strict language server

* Proxy mutative-seeming methods

* Bump version to 2.2.2

package.json

@@ -1,6 +1,6 @@
 {
   "name": "typescript-strict-plugin",
-  "version": "2.2.1",
+  "version": "2.2.2",
   "description": "Typescript tools that help with migration to the strict mode",
   "author": "Allegro",
   "contributors": [

src/plugin/index.ts

@@ -1,22 +1,37 @@
 import { PluginStrictFileChecker } from './PluginStrictFileChecker';
-import { log, PluginInfo, setupProxy, turnOffStrictMode, turnOnStrictMode } from './utils';
+import {
+  log,
+  PluginInfo,
+  setupLanguageServiceProxy,
+  setupStrictLanguageServiceHostProxy,
+} from './utils';
 import * as ts from 'typescript/lib/tsserverlibrary';
 
-const init: ts.server.PluginModuleFactory = () => {
+const init: ts.server.PluginModuleFactory = ({ typescript }) => {
   function create(info: PluginInfo) {
-    const proxy = setupProxy(info);
+    const proxy = setupLanguageServiceProxy(info);
+
+    const strictLanguageServiceHost = setupStrictLanguageServiceHostProxy(info);
+    const strictLanguageService = typescript.createLanguageService(strictLanguageServiceHost);
+
     log(info, 'Plugin initialized');
 
     proxy.getSemanticDiagnostics = function (filePath) {
       const strictFile = new PluginStrictFileChecker(info).isFileStrict(filePath);
 
       if (strictFile) {
-        turnOnStrictMode(info);
+        return strictLanguageService.getSemanticDiagnostics(filePath);
       } else {
-        turnOffStrictMode(info);
+        return info.languageService.getSemanticDiagnostics(filePath);
       }
-
-      return info.languageService.getSemanticDiagnostics(filePath);
+    };
+    proxy.cleanupSemanticCache = function () {
+      strictLanguageService.cleanupSemanticCache();
+      info.languageService.cleanupSemanticCache();
+    };
+    proxy.dispose = function () {
+      strictLanguageService.dispose();
+      info.languageService.dispose();
     };
 
     return proxy;

src/plugin/utils.ts

@@ -3,15 +3,7 @@ import { PLUGIN_NAME } from '../common/constants';
 
 export type PluginInfo = ts.server.PluginCreateInfo;
 
-export function turnOnStrictMode(info: PluginInfo): void {
-  info.project['compilerOptions'].strict = true;
-}
-
-export function turnOffStrictMode(info: PluginInfo): void {
-  info.project['compilerOptions'].strict = false;
-}
-
-export function setupProxy(info: PluginInfo) {
+export function setupLanguageServiceProxy(info: PluginInfo) {
   const proxy: ts.LanguageService = Object.create(null);
   for (const k of Object.keys(info.languageService) as Array<keyof ts.LanguageService>) {
     const serviceFunction = info.languageService[k];
@@ -22,6 +14,23 @@ export function setupProxy(info: PluginInfo) {
   return proxy;
 }
 
+export function setupStrictLanguageServiceHostProxy(info: PluginInfo): ts.LanguageServiceHost {
+  const host = info.languageServiceHost;
+  const strictGetCompilationSettings = () => {
+    const settings = info.languageServiceHost.getCompilationSettings();
+    return { ...settings, strict: true };
+  };
+  const proxy = new Proxy(host, {
+    get(target, prop, receiver) {
+      if (prop === 'getCompilationSettings') {
+        return strictGetCompilationSettings;
+      }
+      return Reflect.get(target, prop, receiver);
+    },
+  });
+  return proxy;
+}
+
 export function log(info: PluginInfo, message: string) {
   info.project.projectService.logger.info(`[${PLUGIN_NAME}]: ` + message);
 }