[pigeon] Adds annotation options to omit shared classes used in Event Channels (#8566)

fixes flutter/flutter#161291

Author: tarrinneal

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 24.1.0
+
+* [kotlin, swift] Adds annotation options to omit shared classes used in Event Channels.
+
 ## 24.0.0
 
 * **Breaking Change** Relocates some files in `lib` that were not intended for direct client use to `lib/src`.

packages/pigeon/example/app/android/app/src/main/kotlin/dev/flutter/pigeon_example_app/EventChannelMessages.g.kt

@@ -79,8 +79,9 @@ private open class EventChannelMessagesPigeonCodec : StandardMessageCodec() {
 
 val EventChannelMessagesPigeonMethodCodec = StandardMethodCodec(EventChannelMessagesPigeonCodec())
 
-private class PigeonStreamHandler<T>(val wrapper: PigeonEventChannelWrapper<T>) :
-    EventChannel.StreamHandler {
+private class EventChannelMessagesPigeonStreamHandler<T>(
+    val wrapper: EventChannelMessagesPigeonEventChannelWrapper<T>
+) : EventChannel.StreamHandler {
   var pigeonSink: PigeonEventSink<T>? = null
 
   override fun onListen(p0: Any?, sink: EventChannel.EventSink) {
@@ -94,7 +95,7 @@ private class PigeonStreamHandler<T>(val wrapper: PigeonEventChannelWrapper<T>)
   }
 }
 
-interface PigeonEventChannelWrapper<T> {
+interface EventChannelMessagesPigeonEventChannelWrapper<T> {
   open fun onListen(p0: Any?, sink: PigeonEventSink<T>) {}
 
   open fun onCancel(p0: Any?) {}
@@ -114,7 +115,8 @@ class PigeonEventSink<T>(private val sink: EventChannel.EventSink) {
   }
 }
 
-abstract class StreamEventsStreamHandler : PigeonEventChannelWrapper<PlatformEvent> {
+abstract class StreamEventsStreamHandler :
+    EventChannelMessagesPigeonEventChannelWrapper<PlatformEvent> {
   companion object {
     fun register(
         messenger: BinaryMessenger,
@@ -126,7 +128,8 @@ abstract class StreamEventsStreamHandler : PigeonEventChannelWrapper<PlatformEve
       if (instanceName.isNotEmpty()) {
         channelName += ".$instanceName"
       }
-      val internalStreamHandler = PigeonStreamHandler<PlatformEvent>(streamHandler)
+      val internalStreamHandler =
+          EventChannelMessagesPigeonStreamHandler<PlatformEvent>(streamHandler)
       EventChannel(messenger, channelName, EventChannelMessagesPigeonMethodCodec)
           .setStreamHandler(internalStreamHandler)
     }

packages/pigeon/lib/pigeon.dart

@@ -9,7 +9,8 @@ export 'src/dart/dart_generator.dart' show DartOptions;
 export 'src/gobject/gobject_generator.dart' show GObjectOptions;
 export 'src/java/java_generator.dart' show JavaOptions;
 export 'src/kotlin/kotlin_generator.dart'
-    show KotlinOptions, KotlinProxyApiOptions;
+    show KotlinEventChannelOptions, KotlinOptions, KotlinProxyApiOptions;
 export 'src/objc/objc_generator.dart' show ObjcOptions;
 export 'src/pigeon_lib.dart';
-export 'src/swift/swift_generator.dart' show SwiftOptions, SwiftProxyApiOptions;
+export 'src/swift/swift_generator.dart'
+    show SwiftEventChannelOptions, SwiftOptions, SwiftProxyApiOptions;

packages/pigeon/lib/src/ast.dart

@@ -6,9 +6,11 @@ import 'package:collection/collection.dart' show ListEquality;
 import 'package:meta/meta.dart';
 
 import 'generator_tools.dart';
-import 'kotlin/kotlin_generator.dart' show KotlinProxyApiOptions;
+import 'kotlin/kotlin_generator.dart'
+    show KotlinEventChannelOptions, KotlinProxyApiOptions;
 import 'pigeon_lib.dart';
-import 'swift/swift_generator.dart' show SwiftProxyApiOptions;
+import 'swift/swift_generator.dart'
+    show SwiftEventChannelOptions, SwiftProxyApiOptions;
 
 typedef _ListEquals = bool Function(List<Object?>, List<Object?>);
 
@@ -347,9 +349,17 @@ class AstEventChannelApi extends Api {
   AstEventChannelApi({
     required super.name,
     required super.methods,
+    this.kotlinOptions,
+    this.swiftOptions,
     super.documentationComments = const <String>[],
   });
 
+  /// Options for Kotlin generated code for Event Channels.
+  final KotlinEventChannelOptions? kotlinOptions;
+
+  /// Options for Swift generated code for Event Channels.
+  final SwiftEventChannelOptions? swiftOptions;
+
   @override
   String toString() {
     return '(EventChannelApi name:$name methods:$methods documentationComments:$documentationComments)';

packages/pigeon/lib/src/generator_tools.dart

@@ -14,7 +14,7 @@ import 'ast.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '24.0.0';
+const String pigeonVersion = '24.1.0';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/lib/src/kotlin/kotlin_generator.dart

@@ -115,6 +115,18 @@ class KotlinProxyApiOptions {
   final int? minAndroidApi;
 }
 
+/// Options for Kotlin implementation of Event Channels.
+class KotlinEventChannelOptions {
+  /// Construct a [KotlinEventChannelOptions].
+  const KotlinEventChannelOptions({this.includeSharedClasses = true});
+
+  /// Whether to include the shared Event Channel classes in generation.
+  ///
+  /// This should only ever be set to false if you have another generated
+  /// Kotlin file with Event Channels in the same directory.
+  final bool includeSharedClasses;
+}
+
 /// Class that manages all Kotlin code generation.
 class KotlinGenerator extends StructuredGenerator<KotlinOptions> {
   /// Instantiates a Kotlin Generator.
@@ -1018,8 +1030,8 @@ if (wrapped == null) {
   }) {
     indent.newln();
     indent.format('''
-        private class PigeonStreamHandler<T>(
-            val wrapper: PigeonEventChannelWrapper<T>
+        private class ${generatorOptions.fileSpecificClassNameComponent}PigeonStreamHandler<T>(
+            val wrapper: ${generatorOptions.fileSpecificClassNameComponent}PigeonEventChannelWrapper<T>
         ) : EventChannel.StreamHandler {
           var pigeonSink: PigeonEventSink<T>? = null
 
@@ -1034,12 +1046,15 @@ if (wrapped == null) {
           }
         }
 
-        interface PigeonEventChannelWrapper<T> {
+        interface ${generatorOptions.fileSpecificClassNameComponent}PigeonEventChannelWrapper<T> {
           open fun onListen(p0: Any?, sink: PigeonEventSink<T>) {}
 
           open fun onCancel(p0: Any?) {}
         }
+        ''');
 
+    if (api.kotlinOptions?.includeSharedClasses ?? true) {
+      indent.format('''
         class PigeonEventSink<T>(private val sink: EventChannel.EventSink) {
           fun success(value: T) {
             sink.success(value)
@@ -1054,18 +1069,19 @@ if (wrapped == null) {
           }
         }
       ''');
+    }
     addDocumentationComments(
         indent, api.documentationComments, _docCommentSpec);
     for (final Method func in api.methods) {
       indent.format('''
-        abstract class ${toUpperCamelCase(func.name)}StreamHandler : PigeonEventChannelWrapper<${_kotlinTypeForDartType(func.returnType)}> {
+        abstract class ${toUpperCamelCase(func.name)}StreamHandler : ${generatorOptions.fileSpecificClassNameComponent}PigeonEventChannelWrapper<${_kotlinTypeForDartType(func.returnType)}> {
           companion object {
             fun register(messenger: BinaryMessenger, streamHandler: ${toUpperCamelCase(func.name)}StreamHandler, instanceName: String = "") {
               var channelName: String = "${makeChannelName(api, func, dartPackageName)}"
               if (instanceName.isNotEmpty()) {
                 channelName += ".\$instanceName"
               }
-              val internalStreamHandler = PigeonStreamHandler<${_kotlinTypeForDartType(func.returnType)}>(streamHandler)
+              val internalStreamHandler = ${generatorOptions.fileSpecificClassNameComponent}PigeonStreamHandler<${_kotlinTypeForDartType(func.returnType)}>(streamHandler)
               EventChannel(messenger, channelName, ${generatorOptions.fileSpecificClassNameComponent}$_pigeonMethodChannelCodec).setStreamHandler(internalStreamHandler)
             }
           }

packages/pigeon/lib/src/pigeon_lib.dart

@@ -169,7 +169,13 @@ class ProxyApi {
 /// defined return type of the method definition.
 class EventChannelApi {
   /// Constructor.
-  const EventChannelApi();
+  const EventChannelApi({this.kotlinOptions, this.swiftOptions});
+
+  /// Options for Kotlin generated code for Event Channels.
+  final KotlinEventChannelOptions? kotlinOptions;
+
+  /// Options for Swift generated code for Event Channels.
+  final SwiftEventChannelOptions? swiftOptions;
 }
 
 /// Metadata to annotation methods to control the selector used for objc output.
@@ -1082,6 +1088,8 @@ List<Error> _validateAst(Root root, String source) {
     }
   }
 
+  bool containsEventChannelApi = false;
+
   for (final Api api in root.apis) {
     final String? matchingPrefix = _findMatchingPrefixOrNull(
       api.name,
@@ -1093,6 +1101,15 @@ List<Error> _validateAst(Root root, String source) {
             'API name must not begin with "$matchingPrefix" in API "${api.name}"',
       ));
     }
+    if (api is AstEventChannelApi) {
+      if (containsEventChannelApi) {
+        result.add(Error(
+          message:
+              'Event Channel methods must all be included in a single EventChannelApi',
+        ));
+      }
+      containsEventChannelApi = true;
+    }
     if (api is AstProxyApi) {
       result.addAll(_validateProxyApi(
         api,
@@ -1885,9 +1902,43 @@ class _RootBuilder extends dart_ast_visitor.RecursiveAstVisitor<Object?> {
               _documentationCommentsParser(node.documentationComment?.tokens),
         );
       } else if (_hasMetadata(node.metadata, 'EventChannelApi')) {
+        final dart_ast.Annotation annotation = node.metadata.firstWhere(
+          (dart_ast.Annotation element) =>
+              element.name.name == 'EventChannelApi',
+        );
+
+        final Map<String, Object?> annotationMap = <String, Object?>{};
+        for (final dart_ast.Expression expression
+            in annotation.arguments!.arguments) {
+          if (expression is dart_ast.NamedExpression) {
+            annotationMap[expression.name.label.name] =
+                _expressionToMap(expression.expression);
+          }
+        }
+
+        SwiftEventChannelOptions? swiftOptions;
+        KotlinEventChannelOptions? kotlinOptions;
+        final Map<String, Object?>? swiftOptionsMap =
+            annotationMap['swiftOptions'] as Map<String, Object?>?;
+        if (swiftOptionsMap != null) {
+          swiftOptions = SwiftEventChannelOptions(
+            includeSharedClasses:
+                swiftOptionsMap['includeSharedClasses'] as bool? ?? true,
+          );
+        }
+        final Map<String, Object?>? kotlinOptionsMap =
+            annotationMap['kotlinOptions'] as Map<String, Object?>?;
+        if (kotlinOptionsMap != null) {
+          kotlinOptions = KotlinEventChannelOptions(
+            includeSharedClasses:
+                kotlinOptionsMap['includeSharedClasses'] as bool? ?? true,
+          );
+        }
         _currentApi = AstEventChannelApi(
           name: node.name.lexeme,
           methods: <Method>[],
+          swiftOptions: swiftOptions,
+          kotlinOptions: kotlinOptions,
           documentationComments:
               _documentationCommentsParser(node.documentationComment?.tokens),
         );

packages/pigeon/lib/src/swift/swift_generator.dart

@@ -125,6 +125,18 @@ class SwiftProxyApiOptions {
   final bool supportsMacos;
 }
 
+/// Options for Swift implementation of Event Channels.
+class SwiftEventChannelOptions {
+  /// Constructs a [SwiftEventChannelOptions].
+  const SwiftEventChannelOptions({this.includeSharedClasses = true});
+
+  /// Whether to include the error class in generation.
+  ///
+  /// This should only ever be set to false if you have another generated
+  /// Swift file with Event Channels in the same directory.
+  final bool includeSharedClasses;
+}
+
 /// Class that manages all Swift code generation.
 class SwiftGenerator extends StructuredGenerator<SwiftOptions> {
   /// Instantiates a Swift Generator.
@@ -1362,7 +1374,9 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
           wrapper.onCancel(withArguments: arguments)
           return nil
         }
-      }
+      }''');
+    if (api.swiftOptions?.includeSharedClasses ?? true) {
+      indent.format('''
 
       class PigeonEventChannelWrapper<ReturnType> {
         func onListen(withArguments arguments: Any?, sink: PigeonEventSink<ReturnType>) {}
@@ -1390,6 +1404,7 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
       
       }
       ''');
+    }
     addDocumentationComments(
         indent, api.documentationComments, _docCommentSpec);
     for (final Method func in api.methods) {

packages/pigeon/pigeons/event_channel_without_classes_tests.dart

@@ -0,0 +1,14 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:pigeon/pigeon.dart';
+
+// This file exists to test compilation for multi-file event channel usage.
+
+@EventChannelApi(
+    swiftOptions: SwiftEventChannelOptions(includeSharedClasses: false),
+    kotlinOptions: KotlinEventChannelOptions(includeSharedClasses: false))
+abstract class EventChannelMethods {
+  int streamIntsAgain();
+}

packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/event_channel_without_classes_tests.gen.dart

@@ -0,0 +1,49 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// Autogenerated from Pigeon, do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+// ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import, no_leading_underscores_for_local_identifiers
+
+import 'dart:async';
+import 'dart:typed_data' show Float64List, Int32List, Int64List, Uint8List;
+
+import 'package:flutter/foundation.dart' show ReadBuffer, WriteBuffer;
+import 'package:flutter/services.dart';
+
+class _PigeonCodec extends StandardMessageCodec {
+  const _PigeonCodec();
+  @override
+  void writeValue(WriteBuffer buffer, Object? value) {
+    if (value is int) {
+      buffer.putUint8(4);
+      buffer.putInt64(value);
+    } else {
+      super.writeValue(buffer, value);
+    }
+  }
+
+  @override
+  Object? readValueOfType(int type, ReadBuffer buffer) {
+    switch (type) {
+      default:
+        return super.readValueOfType(type, buffer);
+    }
+  }
+}
+
+const StandardMethodCodec pigeonMethodCodec =
+    StandardMethodCodec(_PigeonCodec());
+
+Stream<int> streamIntsAgain({String instanceName = ''}) {
+  if (instanceName.isNotEmpty) {
+    instanceName = '.$instanceName';
+  }
+  final EventChannel streamIntsAgainChannel = EventChannel(
+      'dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamIntsAgain$instanceName',
+      pigeonMethodCodec);
+  return streamIntsAgainChannel.receiveBroadcastStream().map((dynamic event) {
+    return event as int;
+  });
+}