Add two Functions to dartdev to allow the extension of cli tool.

Change-Id: I84e89d2c5404949a5b4aa27c17ea793a5cc92531
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/208480
Commit-Queue: Jaime Wren <jwren@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

Author: jwren

pkg/dartdev/lib/src/analysis_server.dart

@@ -9,24 +9,31 @@ import 'dart:io';
 import 'package:analysis_server/src/server/driver.dart' show Driver;
 import 'package:analysis_server_client/protocol.dart'
     show EditBulkFixesResult, ResponseDecoder;
+import 'package:args/args.dart';
 import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
 
 import 'core.dart';
 import 'sdk.dart';
 import 'utils.dart';
 
+/// When set, this function is executed just before the Analysis Server starts.
+void Function(String cmdName, List<FileSystemEntity> analysisRoots,
+    ArgResults argResults) preAnalysisServerStart;
+
 /// A class to provide an API wrapper around an analysis server process.
 class AnalysisServer {
   AnalysisServer(
     this.sdkPath,
     this.analysisRoots, {
     @required this.commandName,
+    @required this.argResults,
   });
 
   final Directory sdkPath;
   final List<FileSystemEntity> analysisRoots;
   final String commandName;
+  final ArgResults argResults;
 
   Process _process;
 
@@ -69,6 +76,7 @@ class AnalysisServer {
   final Map<String, Completer<Map<String, dynamic>>> _requestCompleters = {};
 
   Future<void> start() async {
+    preAnalysisServerStart?.call(commandName, analysisRoots, argResults);
     final List<String> command = <String>[
       sdk.analysisServerSnapshot,
       '--${Driver.SUPPRESS_ANALYTICS_FLAG}',

pkg/dartdev/lib/src/commands/analyze.dart

@@ -100,6 +100,7 @@ class AnalyzeCommand extends DartdevCommand {
       io.Directory(sdk.sdkPath),
       targets,
       commandName: 'analyze',
+      argResults: argResults,
     );
 
     server.onErrors.listen((FileAnalysisErrors fileErrors) {

pkg/dartdev/lib/src/commands/fix.dart

@@ -93,6 +93,7 @@ To use the tool, run either ['dart fix --dry-run'] for a preview of the proposed
       io.Directory(sdk.sdkPath),
       [dir],
       commandName: 'fix',
+      argResults: argResults,
     );
 
     await server.start();

pkg/dartdev/lib/src/core.dart

@@ -18,6 +18,10 @@ import 'utils.dart';
 Logger log;
 bool isDiagnostics = false;
 
+/// When set, this function is executed from the [DartdevCommand] constructor to
+/// contribute additional flags.
+void Function(ArgParser argParser, String cmdName) flagContributor;
+
 abstract class DartdevCommand extends Command<int> {
   final String _name;
   final String _description;
@@ -29,7 +33,9 @@ abstract class DartdevCommand extends Command<int> {
   final bool hidden;
 
   DartdevCommand(this._name, this._description, this._verbose,
-      {this.hidden = false});
+      {this.hidden = false}) {
+    flagContributor?.call(argParser, _name);
+  }
 
   @override
   String get name => _name;

pkg/dartdev/test/analysis_server_test.dart

@@ -25,14 +25,14 @@ void main() {
 
     test('can start', () async {
       AnalysisServer server = AnalysisServer(io.Directory(sdk.sdkPath), [p.dir],
-          commandName: 'testing');
+          commandName: 'testing', argResults: null);
       await server.start();
       await server.shutdown();
     });
 
     test('can send message', () async {
       AnalysisServer server = AnalysisServer(io.Directory(sdk.sdkPath), [p.dir],
-          commandName: 'testing');
+          commandName: 'testing', argResults: null);
       await server.start();
 
       final response = await server.getVersion();