[pigeon]Support EventChannelApi in multiple interface files #161291
Description
Use case
In my project, I organize interface definitions across multiple files. I want to define EventChannelApi in multiple files using the @EventChannelApi() annotation.
However, this results in the generation of duplicate classes (e.g., PigeonEventChannelWrapper and PigeonEventSink in Swift), which causes build errors.
Code Example
Input files
a.dart
import 'package:pigeon/pigeon.dart';
@ConfigurePigeon(PigeonOptions(
dartOut: 'lib/src/a.g.dart',
dartOptions: DartOptions(),
kotlinOut: 'android/app/src/main/kotlin/dev/flutter/pigeon_sample/A.g.kt',
kotlinOptions: KotlinOptions(),
swiftOut: 'ios/Runner/A.g.swift',
swiftOptions: SwiftOptions(),
))
@EventChannelApi()
abstract class EventA {
int streamA();
}b.dart
import 'package:pigeon/pigeon.dart';
@ConfigurePigeon(PigeonOptions(
dartOut: 'lib/src/b.g.dart',
dartOptions: DartOptions(),
kotlinOut: 'android/app/src/main/kotlin/dev/flutter/pigeon_sample/B.g.kt',
kotlinOptions: KotlinOptions(includeErrorClass: false),
swiftOut: 'ios/Runner/B.g.swift',
swiftOptions: SwiftOptions(includeErrorClass: false),
))
@EventChannelApi()
abstract class EventB {
int streamB();
}Output files
A.g.swift
// Autogenerated from Pigeon (v22.7.2), do not edit directly.
// See also: https://pub.dev/packages/pigeon
import Foundation
#if os(iOS)
import Flutter
#elseif os(macOS)
import FlutterMacOS
#else
#error("Unsupported platform.")
#endif
/// Error class for passing custom error details to Dart side.
final class PigeonError: Error {
let code: String
let message: String?
let details: Any?
init(code: String, message: String?, details: Any?) {
self.code = code
self.message = message
self.details = details
}
var localizedDescription: String {
return
"PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>")"
}
}
private func isNullish(_ value: Any?) -> Bool {
return value is NSNull || value == nil
}
private func nilOrValue<T>(_ value: Any?) -> T? {
if value is NSNull { return nil }
return value as! T?
}
private class APigeonCodecReader: FlutterStandardReader {
}
private class APigeonCodecWriter: FlutterStandardWriter {
}
private class APigeonCodecReaderWriter: FlutterStandardReaderWriter {
override func reader(with data: Data) -> FlutterStandardReader {
return APigeonCodecReader(data: data)
}
override func writer(with data: NSMutableData) -> FlutterStandardWriter {
return APigeonCodecWriter(data: data)
}
}
class APigeonCodec: FlutterStandardMessageCodec, @unchecked Sendable {
static let shared = APigeonCodec(readerWriter: APigeonCodecReaderWriter())
}
var aPigeonMethodCodec = FlutterStandardMethodCodec(readerWriter: APigeonCodecReaderWriter());
private class PigeonStreamHandler<ReturnType>: NSObject, FlutterStreamHandler {
private let wrapper: PigeonEventChannelWrapper<ReturnType>
private var pigeonSink: PigeonEventSink<ReturnType>? = nil
init(wrapper: PigeonEventChannelWrapper<ReturnType>) {
self.wrapper = wrapper
}
func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink)
-> FlutterError?
{
pigeonSink = PigeonEventSink<ReturnType>(events)
wrapper.onListen(withArguments: arguments, sink: pigeonSink!)
return nil
}
func onCancel(withArguments arguments: Any?) -> FlutterError? {
pigeonSink = nil
wrapper.onCancel(withArguments: arguments)
return nil
}
}
class PigeonEventChannelWrapper<ReturnType> {
func onListen(withArguments arguments: Any?, sink: PigeonEventSink<ReturnType>) {}
func onCancel(withArguments arguments: Any?) {}
}
class PigeonEventSink<ReturnType> {
private let sink: FlutterEventSink
init(_ sink: @escaping FlutterEventSink) {
self.sink = sink
}
func success(_ value: ReturnType) {
sink(value)
}
func error(code: String, message: String?, details: Any?) {
sink(FlutterError(code: code, message: message, details: details))
}
func endOfStream() {
sink(FlutterEndOfEventStream)
}
}
class StreamAStreamHandler: PigeonEventChannelWrapper<Int64> {
static func register(with messenger: FlutterBinaryMessenger,
instanceName: String = "",
streamHandler: StreamAStreamHandler) {
var channelName = "dev.flutter.pigeon.pigeon_sample.EventA.streamA"
if !instanceName.isEmpty {
channelName += ".\(instanceName)"
}
let internalStreamHandler = PigeonStreamHandler<Int64>(wrapper: streamHandler)
let channel = FlutterEventChannel(name: channelName, binaryMessenger: messenger, codec: aPigeonMethodCodec)
channel.setStreamHandler(internalStreamHandler)
}
}
B.g.swift
// Autogenerated from Pigeon (v22.7.2), do not edit directly.
// See also: https://pub.dev/packages/pigeon
import Foundation
#if os(iOS)
import Flutter
#elseif os(macOS)
import FlutterMacOS
#else
#error("Unsupported platform.")
#endif
private func isNullish(_ value: Any?) -> Bool {
return value is NSNull || value == nil
}
private func nilOrValue<T>(_ value: Any?) -> T? {
if value is NSNull { return nil }
return value as! T?
}
private class BPigeonCodecReader: FlutterStandardReader {
}
private class BPigeonCodecWriter: FlutterStandardWriter {
}
private class BPigeonCodecReaderWriter: FlutterStandardReaderWriter {
override func reader(with data: Data) -> FlutterStandardReader {
return BPigeonCodecReader(data: data)
}
override func writer(with data: NSMutableData) -> FlutterStandardWriter {
return BPigeonCodecWriter(data: data)
}
}
class BPigeonCodec: FlutterStandardMessageCodec, @unchecked Sendable {
static let shared = BPigeonCodec(readerWriter: BPigeonCodecReaderWriter())
}
var bPigeonMethodCodec = FlutterStandardMethodCodec(readerWriter: BPigeonCodecReaderWriter());
private class PigeonStreamHandler<ReturnType>: NSObject, FlutterStreamHandler {
private let wrapper: PigeonEventChannelWrapper<ReturnType>
private var pigeonSink: PigeonEventSink<ReturnType>? = nil
init(wrapper: PigeonEventChannelWrapper<ReturnType>) {
self.wrapper = wrapper
}
func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink)
-> FlutterError?
{
pigeonSink = PigeonEventSink<ReturnType>(events)
wrapper.onListen(withArguments: arguments, sink: pigeonSink!)
return nil
}
func onCancel(withArguments arguments: Any?) -> FlutterError? {
pigeonSink = nil
wrapper.onCancel(withArguments: arguments)
return nil
}
}
class PigeonEventChannelWrapper<ReturnType> {
func onListen(withArguments arguments: Any?, sink: PigeonEventSink<ReturnType>) {}
func onCancel(withArguments arguments: Any?) {}
}
class PigeonEventSink<ReturnType> {
private let sink: FlutterEventSink
init(_ sink: @escaping FlutterEventSink) {
self.sink = sink
}
func success(_ value: ReturnType) {
sink(value)
}
func error(code: String, message: String?, details: Any?) {
sink(FlutterError(code: code, message: message, details: details))
}
func endOfStream() {
sink(FlutterEndOfEventStream)
}
}
class StreamBStreamHandler: PigeonEventChannelWrapper<Int64> {
static func register(with messenger: FlutterBinaryMessenger,
instanceName: String = "",
streamHandler: StreamBStreamHandler) {
var channelName = "dev.flutter.pigeon.pigeon_sample.EventB.streamB"
if !instanceName.isEmpty {
channelName += ".\(instanceName)"
}
let internalStreamHandler = PigeonStreamHandler<Int64>(wrapper: streamHandler)
let channel = FlutterEventChannel(name: channelName, binaryMessenger: messenger, codec: bPigeonMethodCodec)
channel.setStreamHandler(internalStreamHandler)
}
}
Proposal
I propose introducing a new configuration option in SwiftOptions and KotlinOptions to control the generation of shared utility classes (e.g., PigeonEventChannelWrapper and PigeonEventSink) similar to the includeErrorClass option.