[pigeon] Kotlin implementation for ProxyApis

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 22.1.0
+
+* [kotlin] Adds implementation for `@ProxyApi`.
+
 ## 22.0.0
 
 * [dart] Changes codec to send int64 instead of int32.

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

@@ -84,7 +84,7 @@ data class MessageData(
  }
 }
 
-private object MessagesPigeonCodec : StandardMessageCodec() {
+private open class MessagesPigeonCodec : StandardMessageCodec() {
  override fun readValueOfType(type: Byte, buffer: ByteBuffer): Any? {
  return when (type) {
  129.toByte() -> {
@@ -122,7 +122,7 @@ interface ExampleHostApi {
 
  companion object {
  /** The codec used by ExampleHostApi. */
- val codec: MessageCodec<Any?> by lazy { MessagesPigeonCodec }
+ val codec: MessageCodec<Any?> by lazy { MessagesPigeonCodec() }
  /** Sets up an instance of `ExampleHostApi` to handle messages through the `binaryMessenger`. */
  @JvmOverloads
  fun setUp(
@@ -209,7 +209,7 @@ class MessageFlutterApi(
 ) {
  companion object {
  /** The codec used by MessageFlutterApi. */
- val codec: MessageCodec<Any?> by lazy { MessagesPigeonCodec }
+ val codec: MessageCodec<Any?> by lazy { MessagesPigeonCodec() }
  }
 
  fun flutterMethod(aStringArg: String?, callback: (Result<String>) -> Unit) {

packages/pigeon/lib/ast.dart

@@ -4,7 +4,9 @@
 
 import 'package:collection/collection.dart' show ListEquality;
 import 'package:meta/meta.dart';
+
 import 'generator_tools.dart';
+import 'kotlin_generator.dart' show KotlinProxyApiOptions;
 import 'pigeon_lib.dart';
 
 typedef _ListEquals = bool Function(List<Object?>, List<Object?>);
@@ -140,6 +142,7 @@ class AstProxyApi extends Api {
  required this.fields,
  this.superClass,
  this.interfaces = const <TypeDeclaration>{},
+ this.kotlinOptions,
  });
 
  /// List of constructors inside the API.
@@ -154,6 +157,10 @@ class AstProxyApi extends Api {
  /// Name of the classes this class considers to be implemented.
  Set<TypeDeclaration> interfaces;
 
+ /// Options that control how Kotlin code will be generated for a specific
+ /// ProxyApi.
+ final KotlinProxyApiOptions? kotlinOptions;
+
  /// Methods implemented in the host platform language.
  Iterable<Method> get hostMethods => methods.where(
  (Method method) => method.location == ApiLocation.host,
@@ -253,7 +260,7 @@ class AstProxyApi extends Api {
  }
  }
 
- /// Whether the api has a method that callbacks to Dart to add a new instance
+ /// Whether the API has a method that callbacks to Dart to add a new instance
  /// to the InstanceManager.
  ///
  /// This is possible as long as no callback methods are required to
@@ -265,6 +272,21 @@ class AstProxyApi extends Api {
  .every((Method method) => !method.isRequired);
  }
 
+ /// Whether the API has any message calls from Dart to host.
+ bool hasAnyHostMessageCalls() =>
+ constructors.isNotEmpty ||
+ attachedFields.isNotEmpty ||
+ hostMethods.isNotEmpty;
+
+ /// Whether the API has any message calls from host to Dart.
+ bool hasAnyFlutterMessageCalls() =>
+ hasCallbackConstructor() || flutterMethods.isNotEmpty;
+
+ /// Whether the host proxy API class will have methods that need to be
+ /// implemented.
+ bool hasMethodsRequiringImplementation() =>
+ hasAnyHostMessageCalls() || unattachedFields.isNotEmpty;
+
  // Recursively search for all the interfaces apis from a list of names of
  // interfaces.
  //

packages/pigeon/lib/dart/templates.dart

@@ -4,6 +4,20 @@
 
 import '../generator_tools.dart';
 
+/// Name for the generated InstanceManager for ProxyApis.
+///
+/// This lowers the chances of variable name collisions with user defined
+/// parameters.
+const String dartInstanceManagerClassName =
+ '${proxyApiClassNamePrefix}InstanceManager';
+
+/// Name for the generated InstanceManager API for ProxyApis.
+///
+/// This lowers the chances of variable name collisions with user defined
+/// parameters.
+const String dartInstanceManagerApiClassName =
+ '_${classNamePrefix}InstanceManagerApi';
+
 /// Creates the `InstanceManager` with the passed string values.
 String instanceManagerTemplate({
  required Iterable<String> allProxyApiNames,
@@ -30,9 +44,9 @@ String instanceManagerTemplate({
 /// is added as a weak reference with the same identifier. This prevents a
 /// scenario where the weak referenced instance was released and then later
 /// returned by the host platform.
-class $instanceManagerClassName {
- /// Constructs a [$instanceManagerClassName].
- $instanceManagerClassName({required void Function(int) onWeakReferenceRemoved}) {
+class $dartInstanceManagerClassName {
+ /// Constructs a [$dartInstanceManagerClassName].
+ $dartInstanceManagerClassName({required void Function(int) onWeakReferenceRemoved}) {
  this.onWeakReferenceRemoved = (int identifier) {
  _weakInstances.remove(identifier);
  onWeakReferenceRemoved(identifier);
@@ -46,12 +60,12 @@ class $instanceManagerClassName {
  // 0 <= n < 2^16.
  static const int _maxDartCreatedIdentifier = 65536;
 
- /// The default [$instanceManagerClassName] used by ProxyApis.
+ /// The default [$dartInstanceManagerClassName] used by ProxyApis.
  ///
  /// On creation, this manager makes a call to clear the native
  /// InstanceManager. This is to prevent identifier conflicts after a host
  /// restart.
- static final $instanceManagerClassName instance = _initInstance();
+ static final $dartInstanceManagerClassName instance = _initInstance();
 
  // Expando is used because it doesn't prevent its keys from becoming
  // inaccessible. This allows the manager to efficiently retrieve an identifier
@@ -72,17 +86,17 @@ class $instanceManagerClassName {
  /// or becomes inaccessible.
  late final void Function(int) onWeakReferenceRemoved;
 
- static $instanceManagerClassName _initInstance() {
+ static $dartInstanceManagerClassName _initInstance() {
  WidgetsFlutterBinding.ensureInitialized();
- final _${instanceManagerClassName}Api api = _${instanceManagerClassName}Api();
- // Clears the native `$instanceManagerClassName` on the initial use of the Dart one.
+ final $dartInstanceManagerApiClassName api = $dartInstanceManagerApiClassName();
+ // Clears the native `$dartInstanceManagerClassName` on the initial use of the Dart one.
  api.clear();
- final $instanceManagerClassName instanceManager = $instanceManagerClassName(
+ final $dartInstanceManagerClassName instanceManager = $dartInstanceManagerClassName(
  onWeakReferenceRemoved: (int identifier) {
  api.removeStrongReference(identifier);
  },
  );
- _${instanceManagerClassName}Api.setUpMessageHandlers(instanceManager: instanceManager);
+ $dartInstanceManagerApiClassName.setUpMessageHandlers(instanceManager: instanceManager);
  ${apiHandlerSetUps.join('\n\t\t')}
  return instanceManager;
  }
@@ -229,9 +243,9 @@ abstract class $proxyApiBaseClassName {
  /// Construct a [$proxyApiBaseClassName].
  $proxyApiBaseClassName({
  this.$_proxyApiBaseClassMessengerVarName,
- $instanceManagerClassName? $_proxyApiBaseClassInstanceManagerVarName,
+ $dartInstanceManagerClassName? $_proxyApiBaseClassInstanceManagerVarName,
  }) : $_proxyApiBaseClassInstanceManagerVarName =
- $_proxyApiBaseClassInstanceManagerVarName ?? $instanceManagerClassName.instance;
+ $_proxyApiBaseClassInstanceManagerVarName ?? $dartInstanceManagerClassName.instance;
 
  /// Sends and receives binary data across the Flutter platform barrier.
  ///
@@ -242,12 +256,12 @@ abstract class $proxyApiBaseClassName {
 
  /// Maintains instances stored to communicate with native language objects.
  @protected
- final $instanceManagerClassName $_proxyApiBaseClassInstanceManagerVarName;
+ final $dartInstanceManagerClassName $_proxyApiBaseClassInstanceManagerVarName;
 
  /// Instantiates and returns a functionally identical object to oneself.
  ///
  /// Outside of tests, this method should only ever be called by
- /// [$instanceManagerClassName].
+ /// [$dartInstanceManagerClassName].
  ///
  /// Subclasses should always override their parent's implementation of this
  /// method.
@@ -264,11 +278,11 @@ abstract class $proxyApiBaseClassName {
 const String proxyApiBaseCodec = '''
 class $_proxyApiCodecName extends _PigeonCodec {
  const $_proxyApiCodecName(this.instanceManager);
- final $instanceManagerClassName instanceManager;
+ final $dartInstanceManagerClassName instanceManager;
  @override
  void writeValue(WriteBuffer buffer, Object? value) {
  if (value is $proxyApiBaseClassName) {
- buffer.putUint8(128);
+ buffer.putUint8($proxyApiCodecInstanceManagerKey);
  writeValue(buffer, instanceManager.getIdentifier(value));
  } else {
  super.writeValue(buffer, value);
@@ -277,7 +291,7 @@ class $_proxyApiCodecName extends _PigeonCodec {
  @override
  Object? readValueOfType(int type, ReadBuffer buffer) {
  switch (type) {
- case 128:
+ case $proxyApiCodecInstanceManagerKey:
  return instanceManager
  .getInstanceWithWeakReference(readValue(buffer)! as int);
  default: