Add a few features

lib/generator.dart

 library discovery_api_client_generator;
 
 import "dart:io";
 import "dart:async";
 import "dart:convert";
 import 'package:google_discovery_v1_api/discovery_v1_api_client.dart';
 import 'package:google_discovery_v1_api/discovery_v1_api_console.dart';
 
 part "src/apis_package_generator.dart";
 part "src/config.dart";
 part "src/dart_api_library.dart";
 part "src/dart_api_test_library.dart";
 part "src/dart_comments.dart";
 part "src/dart_resources.dart";
 part "src/dart_schemas.dart";
 part "src/namer.dart";
 part "src/utils.dart";
 part "src/uri_template.dart";
 
+
+Future<List<DirectoryListItems>> listAllApis() {
+  return _discoveryClient.apis.list().then((DirectoryList list) {
+    return list.items;
+  });
+}
+
 List<GenerateResult> generateApiPackage(
     List<RestDescription> descriptions, String outputDirectory) {
   var config = new Config('googleapis', '0.1.0-dev');
   var apisPackageGenerator = new ApisPackageGenerator(
       descriptions, config, outputDirectory);
 
   return apisPackageGenerator.generateApiPackage();
 }
 
 List<GenerateResult> generateAllLibraries(String inputDirectory,
                                           String outputDirectory) {
   var apiDescriptions = new Directory(inputDirectory).listSync()
       .where((fse) => fse is File && fse.path.endsWith('.json'))
       .map((File file) {
     return new RestDescription.fromJson(JSON.decode(file.readAsStringSync()));
   }).toList();
   return generateApiPackage(apiDescriptions, outputDirectory);
 }
 
-Future<List<GenerateResult>> downloadDiscoveryDocuments(String outputDir) {
+Future<List<GenerateResult>> downloadDiscoveryDocuments(
+    String outputDir, {List<String> ids}) {
   var apiDescriptions = <RestDescription>[];
 
   return _discoveryClient.apis.list().then((DirectoryList list) {
     var futures = <Future>[];
     for (var item in list.items) {
-      futures.add(_discoveryClient.apis.getRest(item.name, item.version)
-          .then((doc) {
-        apiDescriptions.add(doc);
-      }));
+      if (ids == null || ids.contains(item.id)) {
+        futures.add(_discoveryClient.apis.getRest(item.name, item.version)
+            .then((doc) {
+          apiDescriptions.add(doc);
+        }));
+      }
     }
     return Future.wait(futures);
   }).then((_) {
     var directory = new Directory(outputDir);
     if (directory.existsSync()) {
       print('Deleting directory $outputDir.');
       directory.deleteSync(recursive: true);
     }
-    directory.createSync();
+    directory.createSync(recursive: true);
 
     for (var description in apiDescriptions) {
       var name = '$outputDir/${description.name}__${description.version}.json';
       var file = new File(name);
       var encoder = new JsonEncoder.withIndent('    ');
       file.writeAsStringSync(encoder.convert(description.toJson()));
       print('Written: $name');
     }
   });
 }
@@ skipping 25 matching lines @@
       => cleanName("${apiName}_${apiVersion}_api").toLowerCase();
 
   String toString() {
     var flag = success ? '[SUCCESS]' : '[FAIL]';
     var msg = message != null && !message.isEmpty ? ':\n  => $message' : '';
     return '$flag $apiName $apiVersion @ $packagePath $msg';
   }
 }
 
 final _discoveryClient = new Discovery();