[pigeon] added null safety flag for dart (#222)

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.1.11
+
+* Added flag to generate null safety annotated Dart code `--dart-null-safety`.
+* Made it so Dart API setup methods can take null.
+
 ## 0.1.10+1
 
 * Updated the examples page.

packages/pigeon/lib/dart_generator.dart

@@ -5,8 +5,15 @@
 import 'ast.dart';
 import 'generator_tools.dart';
 
-void _writeHostApi(Indent indent, Api api) {
+/// Options that control how Dart code will be generated.
+class DartOptions {
+  /// Determines if the generated code has null safety annotations (Dart >2.10 required).
+  bool isNullSafe = false;
+}
+
+void _writeHostApi(DartOptions opt, Indent indent, Api api) {
   assert(api.location == ApiLocation.host);
+  final String nullTag = opt.isNullSafe ? '?' : '';
   indent.write('class ${api.name} ');
   indent.scoped('{', '}', () {
     for (Method func in api.methods) {
@@ -38,7 +45,7 @@ void _writeHostApi(Indent indent, Api api) {
             ? '// noop'
             : 'return ${func.returnType}._fromMap(replyMap[\'${Keys.result}\']);';
         indent.format(
-            '''final Map<dynamic, dynamic> replyMap = await channel.send($sendArgument);
+            '''final Map<dynamic, dynamic>$nullTag replyMap = await channel.send($sendArgument);
 if (replyMap == null) {
 \tthrow PlatformException(
 \t\tcode: 'channel-error',
@@ -60,9 +67,10 @@ if (replyMap == null) {
   indent.writeln('');
 }
 
-void _writeFlutterApi(Indent indent, Api api,
+void _writeFlutterApi(DartOptions opt, Indent indent, Api api,
     {String Function(Method) channelNameFunc, bool isMockHandler = false}) {
   assert(api.location == ApiLocation.flutter);
+  final String nullTag = opt.isNullSafe ? '?' : '';
   indent.write('abstract class ${api.name} ');
   indent.scoped('{', '}', () {
     for (Method func in api.methods) {
@@ -73,7 +81,7 @@ void _writeFlutterApi(Indent indent, Api api,
           func.argType == 'void' ? '' : '${func.argType} arg';
       indent.writeln('$returnType ${func.name}($argSignature);');
     }
-    indent.write('static void setup(${api.name} api) ');
+    indent.write('static void setup(${api.name}$nullTag api) ');
     indent.scoped('{', '}', () {
       for (Method func in api.methods) {
         indent.write('');
@@ -90,8 +98,13 @@ void _writeFlutterApi(Indent indent, Api api,
           indent.dec();
           final String messageHandlerSetter =
               isMockHandler ? 'setMockMessageHandler' : 'setMessageHandler';
-          indent
-              .write('channel.$messageHandlerSetter((dynamic message) async ');
+          indent.write('if (api == null) ');
+          indent.scoped('{', '} else {', () {
+            indent.writeln('channel.$messageHandlerSetter(null);');
+          });
+          indent.scoped('', '}', () {
+            indent.write(
+                'channel.$messageHandlerSetter((dynamic message) async ');
             indent.scoped('{', '});', () {
               final String argType = func.argType;
               final String returnType = func.returnType;
@@ -125,6 +138,7 @@ void _writeFlutterApi(Indent indent, Api api,
               }
             });
           });
+        });
       }
     });
   });
@@ -133,7 +147,7 @@ void _writeFlutterApi(Indent indent, Api api,
 
 /// Generates Dart source code for the given AST represented by [root],
 /// outputting the code to [sink].
-void generateDart(Root root, StringSink sink) {
+void generateDart(DartOptions opt, Root root, StringSink sink) {
   final List<String> customClassNames =
       root.classes.map((Class x) => x.name).toList();
   final Indent indent = Indent(sink);
@@ -141,18 +155,21 @@ void generateDart(Root root, StringSink sink) {
   indent.writeln('// $seeAlsoWarning');
   indent.writeln(
       '// ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import');
-  indent.writeln('// @dart = 2.8');
+  indent.writeln('// @dart = ${opt.isNullSafe ? '2.10' : '2.8'}');
   indent.writeln('import \'dart:async\';');
   indent.writeln('import \'package:flutter/services.dart\';');
   indent.writeln(
       'import \'dart:typed_data\' show Uint8List, Int32List, Int64List, Float64List;');
   indent.writeln('');
 
+  final String nullBang = opt.isNullSafe ? '!' : '';
   for (Class klass in root.classes) {
     sink.write('class ${klass.name} ');
     indent.scoped('{', '}', () {
       for (Field field in klass.fields) {
-        indent.writeln('${field.dataType} ${field.name};');
+        final String datatype =
+            opt.isNullSafe ? '${field.dataType}?' : field.dataType;
+        indent.writeln('$datatype ${field.name};');
       }
       indent.writeln('// ignore: unused_element');
       indent.write('Map<dynamic, dynamic> _toMap() ');
@@ -163,7 +180,7 @@ void generateDart(Root root, StringSink sink) {
           indent.write('pigeonMap[\'${field.name}\'] = ');
           if (customClassNames.contains(field.dataType)) {
             indent.addln(
-                '${field.name} == null ? null : ${field.name}._toMap();');
+                '${field.name} == null ? null : ${field.name}$nullBang._toMap();');
           } else {
             indent.addln('${field.name};');
           }
@@ -174,16 +191,12 @@ void generateDart(Root root, StringSink sink) {
       indent.write(
           'static ${klass.name} _fromMap(Map<dynamic, dynamic> pigeonMap) ');
       indent.scoped('{', '}', () {
-        indent.write('if (pigeonMap == null)');
-        indent.scoped('{', '}', () {
-          indent.writeln('return null;');
-        });
         indent.writeln('final ${klass.name} result = ${klass.name}();');
         for (Field field in klass.fields) {
           indent.write('result.${field.name} = ');
           if (customClassNames.contains(field.dataType)) {
             indent.addln(
-                '${field.dataType}._fromMap(pigeonMap[\'${field.name}\']);');
+                'pigeonMap[\'${field.name}\'] != null ? ${field.dataType}._fromMap(pigeonMap[\'${field.name}\']) : null;');
           } else {
             indent.addln('pigeonMap[\'${field.name}\'];');
           }
@@ -195,18 +208,18 @@ void generateDart(Root root, StringSink sink) {
   }
   for (Api api in root.apis) {
     if (api.location == ApiLocation.host) {
-      _writeHostApi(indent, api);
+      _writeHostApi(opt, indent, api);
       if (api.dartHostTestHandler != null) {
         final Api mockApi = Api(
             name: api.dartHostTestHandler,
             methods: api.methods,
             location: ApiLocation.flutter);
-        _writeFlutterApi(indent, mockApi,
+        _writeFlutterApi(opt, indent, mockApi,
             channelNameFunc: (Method func) => makeChannelName(api, func),
             isMockHandler: true);
       }
     } else if (api.location == ApiLocation.flutter) {
-      _writeFlutterApi(indent, api);
+      _writeFlutterApi(opt, indent, api);
     }
   }
 }

packages/pigeon/lib/generator_tools.dart

@@ -8,7 +8,7 @@ import 'dart:mirrors';
 import 'ast.dart';
 
 /// The current version of pigeon.
-const String pigeonVersion = '0.1.10+1';
+const String pigeonVersion = '0.1.11';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/lib/pigeon_lib.dart

@@ -133,6 +133,9 @@ class PigeonOptions {
 
   /// Options that control how Java will be generated.
   JavaOptions javaOptions = JavaOptions();
+
+  /// Options that control how Dart will be generated.
+  DartOptions dartOptions = DartOptions();
 }
 
 /// A collection of an AST represented as a [Root] and [Error]'s.
@@ -282,6 +285,8 @@ options:
     ..addOption('java_out', help: 'Path to generated Java file (.java).')
     ..addOption('java_package',
         help: 'The package that generated Java code will be in.')
+    ..addFlag('dart_null_safety',
+        help: 'Makes generated Dart code have null safety annotations')
     ..addOption('objc_header_out',
         help: 'Path to generated Objective-C header file (.h).')
     ..addOption('objc_prefix',
@@ -299,6 +304,7 @@ options:
     opts.objcOptions.prefix = results['objc_prefix'];
     opts.javaOut = results['java_out'];
     opts.javaOptions.package = results['java_package'];
+    opts.dartOptions.isNullSafe = results['dart_null_safety'];
     return opts;
   }
 
@@ -402,8 +408,10 @@ options:
         errors.add(Error(message: err.message, filename: options.input));
       }
       if (options.dartOut != null) {
-        await _runGenerator(options.dartOut,
-            (StringSink sink) => generateDart(parseResults.root, sink));
+        await _runGenerator(
+            options.dartOut,
+            (StringSink sink) =>
+                generateDart(options.dartOptions, parseResults.root, sink));
       }
       if (options.objcHeaderOut != null) {
         await _runGenerator(

packages/pigeon/pubspec.yaml

@@ -1,5 +1,5 @@
 name: pigeon
-version: 0.1.10+1
+version: 0.1.11
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 homepage: https://github.com/flutter/packages/tree/master/packages/pigeon
 dependencies:

packages/pigeon/run_tests.sh

@@ -67,6 +67,22 @@ test_pigeon_android() {
   rm -rf $temp_dir
 }
 
+# test_null_safe_dart(<path to pigeon file>)
+#
+# Compiles the pigeon file to a temp directory and attempts to run the dart
+# analyzer on it with null safety turned on.
+test_null_safe_dart() {
+  temp_dir=$(mktemp -d -t pigeon)
+
+  pub run pigeon \
+    --input $1 \
+    --dart_null_safety \
+    --dart_out $temp_dir/pigeon.dart
+
+  dartanalyzer $temp_dir/pigeon.dart --fatal-infos --fatal-warnings --packages ./e2e_tests/test_objc/.packages --enable-experiment=non-nullable
+  rm -rf $temp_dir
+}
+
 ###############################################################################
 # Dart unit tests
 ###############################################################################
@@ -76,7 +92,7 @@ pub run test test/
 ###############################################################################
 # Execute without arguments test
 ###############################################################################
-pub run pigeon
+pub run pigeon 1> /dev/null
 
 ###############################################################################
 # Compilation tests (Code is generated and compiled)
@@ -88,6 +104,7 @@ pushd $PWD
 cd e2e_tests/test_objc/
 flutter pub get
 popd
+test_null_safe_dart ./pigeons/message.dart
 test_pigeon_android ./pigeons/voidflutter.dart
 test_pigeon_android ./pigeons/voidhost.dart
 test_pigeon_android ./pigeons/host2flutter.dart

packages/pigeon/test/dart_generator_test.dart

@@ -20,7 +20,7 @@ void main() {
       ..apis = <Api>[]
       ..classes = <Class>[klass];
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, contains('class Foobar'));
     expect(code, contains('  dataType1 field1;'));
@@ -45,7 +45,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')])
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, contains('class Api'));
     expect(code, matches('Output.*doSomething.*Input'));
@@ -61,14 +61,16 @@ void main() {
           fields: <Field>[Field(name: 'nested', dataType: 'Input')])
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(
         code,
         contains(
             'pigeonMap[\'nested\'] = nested == null ? null : nested._toMap()'));
-    expect(code,
-        contains('result.nested = Input._fromMap(pigeonMap[\'nested\']);'));
+    expect(
+        code,
+        contains(
+            'result.nested = pigeonMap[\'nested\'] != null ? Input._fromMap(pigeonMap[\'nested\']) : null;'));
   });
 
   test('flutterapi', () {
@@ -90,7 +92,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')])
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, contains('abstract class Api'));
     expect(code, contains('static void setup(Api'));
@@ -112,7 +114,7 @@ void main() {
           fields: <Field>[Field(name: 'input', dataType: 'String')]),
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, contains('Future<void> doSomething'));
     expect(code, contains('// noop'));
@@ -134,7 +136,7 @@ void main() {
           fields: <Field>[Field(name: 'input', dataType: 'String')]),
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, isNot(matches('=.*doSomething')));
     expect(code, contains('doSomething('));
@@ -157,7 +159,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')]),
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, matches('output.*=.*doSomething[(][)]'));
     expect(code, contains('Output doSomething();'));
@@ -179,7 +181,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')]),
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, matches('channel\.send[(]null[)]'));
   });
@@ -213,7 +215,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')])
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, matches('abstract class ApiMock'));
     expect(code, isNot(matches('\.ApiMock\.doSomething')));
@@ -233,7 +235,7 @@ void main() {
       ..apis = <Api>[]
       ..classes = <Class>[klass];
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, contains('// @dart = 2.8'));
   });
@@ -257,7 +259,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')])
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, contains('abstract class Api'));
     expect(code, contains('Future<Output> doSomething(Input arg);'));
@@ -284,7 +286,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')])
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, contains('class Api'));
     expect(code, matches('Output.*doSomething.*Input'));
@@ -306,7 +308,7 @@ void main() {
           fields: <Field>[Field(name: 'output', dataType: 'String')]),
     ]);
     final StringBuffer sink = StringBuffer();
-    generateDart(root, sink);
+    generateDart(DartOptions(), root, sink);
     final String code = sink.toString();
     expect(code, matches('channel\.send[(]null[)]'));
   });

packages/pigeon/test/pigeon_lib_test.dart

@@ -237,4 +237,10 @@ void main() {
     final ParseResults results = pigeon.parse(<Type>[InvalidReturnTypeApi]);
     expect(results.errors.length, 1);
   });
+
+  test('null saftey flag', () {
+    final PigeonOptions results =
+        Pigeon.parseArgs(<String>['--dart_null_safety']);
+    expect(results.dartOptions.isNullSafe, true);
+  });
 }