refactor: move command line utils to standalone module (#445)

This commit moves the command line parsing methods to a standalone file
so that they can be shared with the loader (banner) later on.
This is in preparation for removing banner.js and rewrite it in TypeScript
instead to remove code duplication.

Author: Keen Yee Liau

server/src/cmdline_utils.ts

@@ -0,0 +1,65 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+function findArgument(argv: string[], argName: string): string|undefined {
+  const index = argv.indexOf(argName);
+  if (index < 0 || index === argv.length - 1) {
+    return;
+  }
+  return argv[index + 1];
+}
+
+function parseStringArray(argv: string[], argName: string): string[] {
+  const arg = findArgument(argv, argName);
+  if (!arg) {
+    return [];
+  }
+  return arg.split(',');
+}
+
+function hasArgument(argv: string[], argName: string): boolean {
+  return argv.includes(argName);
+}
+
+interface CommandLineOptions {
+  help: boolean;
+  logFile?: string;
+  logVerbosity?: string;
+  ngProbeLocations: string[];
+  tsProbeLocations: string[];
+}
+
+export function parseCommandLine(argv: string[]): CommandLineOptions {
+  return {
+    help: hasArgument(argv, '--help'),
+    logFile: findArgument(argv, '--logFile'),
+    logVerbosity: findArgument(argv, '--logVerbosity'),
+    ngProbeLocations: parseStringArray(argv, '--ngProbeLocations'),
+    tsProbeLocations: parseStringArray(argv, '--tsProbeLocations'),
+  };
+}
+
+export function generateHelpMessage(argv: string[]) {
+  return `Angular Language Service that implements the Language Server Protocol (LSP).
+
+  Usage: ${argv[0]} ${argv[1]} [options]
+
+  Options:
+    --help: Prints help message.
+    --logFile: Location to log messages. Logging is disabled if not provided.
+    --logVerbosity: terse|normal|verbose|requestTime. See ts.server.LogLevel.
+    --ngProbeLocations: Path of @angular/language-service. Required.
+    --tsProbeLocations: Path of typescript. Required.
+
+  Additional options supported by vscode-languageserver:
+    --clientProcessId=<number>: Automatically kills the server if the client process dies.
+    --node-ipc: Communicate using Node's IPC. This is the default.
+    --stdio: Communicate over stdin/stdout.
+    --socket=<number>: Communicate using Unix socket.
+  `;
+}

server/src/server.ts

@@ -6,43 +6,27 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {generateHelpMessage, parseCommandLine} from './cmdline_utils';
 import {createLogger} from './logger';
 import {ServerHost} from './server_host';
 import {Session} from './session';
 import {resolveWithMinMajor} from './version_provider';
 
 // Parse command line arguments
-const help = hasArgument('--help');
-const logFile = findArgument('--logFile');
-const logVerbosity = findArgument('--logVerbosity');
-const ngProbeLocations = parseStringArray('--ngProbeLocations');
-const tsProbeLocations = parseStringArray('--tsProbeLocations');
+const options = parseCommandLine(process.argv);
 
-if (help) {
-  const {argv} = process;
-  console.error(`Angular Language Service that implements the Language Server Protocol (LSP).
-
-Usage: ${argv[0]} ${argv[1]} [options]
-
-Options:
-  --help: Prints help message.
-  --logFile: Location to log messages. Logging is disabled if not provided.
-  --logVerbosity: terse|normal|verbose|requestTime. See ts.server.LogLevel.
-  --ngProbeLocations: Path of @angular/language-service. Required.
-  --tsProbeLocations: Path of typescript. Required.
-
-Additional options supported by vscode-languageserver:
-  --clientProcessId=<number>: Automatically kills the server if the client process dies.
-  --node-ipc: Communicate using Node's IPC. This is the default.
-  --stdio: Communicate over stdin/stdout.
-  --socket=<number>: Communicate using Unix socket.
-`);
+if (options.help) {
+  console.error(generateHelpMessage(process.argv));
   process.exit(0);
 }
 
 // Create a logger that logs to file. OK to emit verbose entries.
-const logger = createLogger({logFile, logVerbosity});
+const logger = createLogger({
+  logFile: options.logFile,
+  logVerbosity: options.logVerbosity,
+});
 
+const {tsProbeLocations, ngProbeLocations} = options;
 const ts = resolveWithMinMajor('typescript', 3, tsProbeLocations);
 const ng = resolveWithMinMajor('@angular/language-service', 9, ngProbeLocations);
 
@@ -69,23 +53,3 @@ if (process.env.TSC_NONPOLLING_WATCHER !== 'true') {
 }
 
 session.listen();
-
-function hasArgument(argName: string): boolean {
-  return process.argv.includes(argName);
-}
-
-function findArgument(argName: string): string|undefined {
-  const index = process.argv.indexOf(argName);
-  if (index < 0 || index === process.argv.length - 1) {
-    return;
-  }
-  return process.argv[index + 1];
-}
-
-function parseStringArray(argName: string): string[] {
-  const arg = findArgument(argName);
-  if (!arg) {
-    return [];
-  }
-  return arg.split(',');
-}

server/src/tests/cmdline_utils_spec.ts

@@ -0,0 +1,36 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {parseCommandLine} from '../cmdline_utils';
+
+describe('parseCommandLine', () => {
+  it('should parse "help"', () => {
+    const options = parseCommandLine(['--help']);
+    expect(options.help).toBe(true);
+  });
+
+  it('should parse "logFile"', () => {
+    const options = parseCommandLine(['--logFile', 'foo.log']);
+    expect(options.logFile).toBe('foo.log');
+  });
+
+  it('should parse "logVerbosity"', () => {
+    const options = parseCommandLine(['--logVerbosity', 'normal']);
+    expect(options.logVerbosity).toBe('normal');
+  });
+
+  it('should parse "ngProbeLocations"', () => {
+    const options = parseCommandLine(['--ngProbeLocations', '/foo,/bar']);
+    expect(options.ngProbeLocations).toEqual(['/foo', '/bar']);
+  });
+
+  it('should parse "tsProbeLocations"', () => {
+    const options = parseCommandLine(['--tsProbeLocations', '/baz,/qux']);
+    expect(options.tsProbeLocations).toEqual(['/baz', '/qux']);
+  });
+});