feat: add --experimental-ivy flag for Ivy language service

This commit adds a hidden flag `--experimental-ivy` to load the Ivy
version of `@angular/language-service`.
This flag is hidden for now because it is only used for development.

The second entry point is resolved from `@angular/language-service/ivy.umd`
but in the next update it'll be `@angular/language-service/ivy` due to
the renaming done in angular/angular#38086

Author: kyliau

server/src/cmdline_utils.ts

@@ -28,6 +28,11 @@ function hasArgument(argv: string[], argName: string): boolean {
 
 interface CommandLineOptions {
   help: boolean;
+  /**
+   * If true, use the Ivy version of Angular LS. For now this is only used for
+   * development.
+   */
+  ivy: boolean;
   logFile?: string;
   logVerbosity?: string;
   ngProbeLocations: string[];
@@ -37,6 +42,7 @@ interface CommandLineOptions {
 export function parseCommandLine(argv: string[]): CommandLineOptions {
   return {
     help: hasArgument(argv, '--help'),
+    ivy: hasArgument(argv, '--experimental-ivy'),
     logFile: findArgument(argv, '--logFile'),
     logVerbosity: findArgument(argv, '--logVerbosity'),
     ngProbeLocations: parseStringArray(argv, '--ngProbeLocations'),
@@ -45,6 +51,7 @@ export function parseCommandLine(argv: string[]): CommandLineOptions {
 }
 
 export function generateHelpMessage(argv: string[]) {
+  // Do not expose --experimental-ivy flag since it's only used for development.
   return `Angular Language Service that implements the Language Server Protocol (LSP).
 
   Usage: ${argv[0]} ${argv[1]} [options]

server/src/server.ts

@@ -27,7 +27,7 @@ const logger = createLogger({
 });
 
 const ts = resolveTsServer(options.tsProbeLocations);
-const ng = resolveNgLangSvc(options.ngProbeLocations);
+const ng = resolveNgLangSvc(options.ngProbeLocations, options.ivy);
 
 // ServerHost provides native OS functionality
 const host = new ServerHost();
@@ -36,13 +36,14 @@ const host = new ServerHost();
 const session = new Session({
   host,
   logger,
+  ngPlugin: ng.name,
   ngProbeLocation: ng.resolvedPath,
 });
 
 // Log initialization info
 session.info(`Angular language server process ID: ${process.pid}`);
-session.info(`Using typescript v${ts.version} from ${ts.resolvedPath}`);
-session.info(`Using @angular/language-service v${ng.version} from ${ng.resolvedPath}`);
+session.info(`Using ${ts.name} v${ts.version} from ${ts.resolvedPath}`);
+session.info(`Using ${ng.name} v${ng.version} from ${ng.resolvedPath}`);
 session.info(`Log file: ${logger.getLogFileName()}`);
 if (process.env.NG_DEBUG === 'true') {
   session.info('Angular Language Service is running under DEBUG mode');

server/src/session.ts

@@ -19,6 +19,7 @@ import {filePathToUri, lspPositionToTsPosition, lspRangeToTsPositions, tsTextSpa
 export interface SessionOptions {
   host: ServerHost;
   logger: Logger;
+  ngPlugin: string;
   ngProbeLocation: string;
 }
 
@@ -62,7 +63,7 @@ export class Session {
       // See https://github.com/angular/vscode-ng-language-service/issues/693
       suppressDiagnosticEvents: true,
       eventHandler: (e) => this.handleProjectServiceEvent(e),
-      globalPlugins: ['@angular/language-service'],
+      globalPlugins: [options.ngPlugin],
       pluginProbeLocations: [options.ngProbeLocation],
       allowLocalPluginLoads: false,  // do not load plugins from tsconfig.json
     });
@@ -79,7 +80,7 @@ export class Session {
     });
 
     projSvc.configurePlugin({
-      pluginName: '@angular/language-service',
+      pluginName: options.ngPlugin,
       configuration: {
         angularOnly: true,
       },

server/src/tests/version_provider_spec.ts

@@ -18,10 +18,20 @@ describe('Node Module Resolver', () => {
   });
 
   it('should be able to resolve Angular language service', () => {
-    const result = resolveNgLangSvc(probeLocations);
+    const result = resolveNgLangSvc(probeLocations, false /* ivy */);
     expect(result).toBeDefined();
+    // TODO: This will fail in the next update of @angular/language-service
+    // because language-service.umd.js is renamed to language-service.js
     expect(result.resolvedPath).toMatch(/language-service.umd.js$/);
   });
+
+  it('should be able to resolve Ivy version of Angular language service', () => {
+    const result = resolveNgLangSvc(probeLocations, true /* ivy */);
+    expect(result).toBeDefined();
+    // TODO: This will fail in the next update of @angular/language-service
+    // because ivy.umd.js is renamed to ivy.js
+    expect(result.resolvedPath).toMatch(/ivy.umd.js$/);
+  });
 });
 
 describe('Version', () => {

server/src/version_provider.ts

@@ -13,6 +13,7 @@ const MIN_NG_VERSION = '10.0';
  * Represents a valid node module that has been successfully resolved.
  */
 interface NodeModule {
+  name: string;
   resolvedPath: string;
   version: Version;
 }
@@ -29,6 +30,7 @@ function resolve(packageName: string, location: string, rootPackage?: string): N
       paths: [location],
     });
     return {
+      name: packageName,
       resolvedPath,
       version: new Version(packageJson.version),
     };
@@ -42,12 +44,13 @@ function resolve(packageName: string, location: string, rootPackage?: string): N
  * @param packageName name of package to be resolved
  * @param minVersionStr minimum version
  * @param probeLocations locations to initiate node module resolution
- * @param rootPackage location of package.json, if different from `packageName`
+ * @param rootPackage location of package.json. For example, the root package of
+ * `typescript/lib/tsserverlibrary` is `typescript`.
  */
 function resolveWithMinVersion(
     packageName: string, minVersionStr: string, probeLocations: string[],
-    rootPackage?: string): NodeModule {
-  if (rootPackage && !packageName.startsWith(rootPackage)) {
+    rootPackage: string): NodeModule {
+  if (!packageName.startsWith(rootPackage)) {
     throw new Error(`${packageName} must be in the root package`);
   }
   const minVersion = new Version(minVersionStr);
@@ -73,11 +76,15 @@ export function resolveTsServer(probeLocations: string[]): NodeModule {
 
 /**
  * Resolve `@angular/language-service` from the given locations.
- * @param probeLocations
+ * @param probeLocations locations from which resolution is attempted
+ * @param ivy true if Ivy language service is requested
  */
-export function resolveNgLangSvc(probeLocations: string[]): NodeModule {
+export function resolveNgLangSvc(probeLocations: string[], ivy: boolean): NodeModule {
   const nglangsvc = '@angular/language-service';
-  return resolveWithMinVersion(nglangsvc, MIN_NG_VERSION, probeLocations);
+  // TODO: In the next update of @angular/language-service, rename this to
+  // bundles/ivy because the file has been renamed
+  const packageName = ivy ? `${nglangsvc}/bundles/ivy.umd` : nglangsvc;
+  return resolveWithMinVersion(packageName, MIN_NG_VERSION, probeLocations, nglangsvc);
 }
 
 /**