Made JavaScriptChannelRegistry available

Author: mvanbeusekom

packages/webview_flutter/webview_flutter_platform_interface/lib/v4/src/javascript_channel_registry.dart

@@ -0,0 +1,45 @@
+// 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:meta/meta.dart';
+
+import 'types/javascript_channel.dart';
+import 'types/javascript_message.dart';
+
+/// Utility class for managing named JavaScript channels and forwarding incoming
+/// messages on the correct channel.
+@sealed
+class JavaScriptChannelRegistry {
+  /// Constructs a [JavaScriptChannelRegistry] initializing it with the given
+  /// set of [JavaScriptChannel]s.
+  JavaScriptChannelRegistry(Set<JavaScriptChannel>? channels) {
+    updateJavaScriptChannelsFromSet(channels);
+  }
+
+  /// Maps a channel name to a channel.
+  final Map<String, JavaScriptChannel> channels = <String, JavaScriptChannel>{};
+
+  /// Invoked when a JavaScript channel message is received.
+  void onJavaScriptChannelMessage(String channel, String message) {
+    final JavaScriptChannel? javaScriptChannel = channels[channel];
+
+    if (javaScriptChannel == null) {
+      throw ArgumentError('No channel registered with name $channel.');
+    }
+
+    javaScriptChannel.onMessageReceived(JavaScriptMessage(message: message));
+  }
+
+  /// Updates the set of [JavaScriptChannel]s with the new set.
+  void updateJavaScriptChannelsFromSet(Set<JavaScriptChannel>? channels) {
+    this.channels.clear();
+    if (channels == null) {
+      return;
+    }
+
+    for (final JavaScriptChannel channel in channels) {
+      this.channels[channel.name] = channel;
+    }
+  }
+}

packages/webview_flutter/webview_flutter_platform_interface/lib/v4/src/types/javascript_channel.dart

@@ -0,0 +1,35 @@
+// 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 'javascript_message.dart';
+
+/// Callback type for handling messages sent from JavaScript running in a web view.
+typedef JavaScriptMessageHandler = void Function(JavaScriptMessage message);
+
+final RegExp _validChannelNames = RegExp(r'^[a-zA-Z_][a-zA-Z0-9_]*$');
+
+/// A named channel for receiving messaged from JavaScript code running inside a web view.
+class JavaScriptChannel {
+  /// Constructs a JavaScript channel.
+  ///
+  /// The parameters `name` and `onMessageReceived` must not be null.
+  JavaScriptChannel({
+    required this.name,
+    required this.onMessageReceived,
+  })  : assert(name != null),
+        assert(onMessageReceived != null),
+        assert(_validChannelNames.hasMatch(name));
+
+  /// The channel's name.
+  ///
+  /// The name must start with a letter or underscore(_), followed by any
+  /// combination of alphabetic characters plus digits.
+  ///
+  /// Note that any JavaScript existing `window` property with this name will be
+  /// overriden.
+  final String name;
+
+  /// A callback that's invoked when a message is received through the channel.
+  final JavaScriptMessageHandler onMessageReceived;
+}

packages/webview_flutter/webview_flutter_platform_interface/lib/v4/src/types/types.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+export 'javascript_channel.dart';
 export 'javascript_message.dart';
 export 'javascript_mode.dart';
 export 'load_request_params.dart';

packages/webview_flutter/webview_flutter_platform_interface/lib/v4/webview_flutter_platform_interface.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+export 'src/javascript_channel_registry.dart';
 export 'src/navigation_callback_delegate.dart';
 export 'src/types/types.dart';
 export 'src/webview_controller_delegate.dart';

packages/webview_flutter/webview_flutter_platform_interface/pubspec.yaml

@@ -13,6 +13,7 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
+  meta: ^1.7.0
   plugin_platform_interface: ^2.1.0
 
 dev_dependencies:

packages/webview_flutter/webview_flutter_platform_interface/test/src/v4/javascript_channel_registry_test.dart

@@ -0,0 +1,118 @@
+// 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:flutter_test/flutter_test.dart';
+import 'package:webview_flutter_platform_interface/v4/src/javaScript_channel_registry.dart';
+import 'package:webview_flutter_platform_interface/v4/src/types/types.dart';
+
+void main() {
+  final Map<String, String> _log = <String, String>{};
+  final Set<JavaScriptChannel> _channels = <JavaScriptChannel>{
+    JavaScriptChannel(
+      name: 'js_channel_1',
+      onMessageReceived: (JavaScriptMessage message) =>
+          _log['js_channel_1'] = message.message,
+    ),
+    JavaScriptChannel(
+      name: 'js_channel_2',
+      onMessageReceived: (JavaScriptMessage message) =>
+          _log['js_channel_2'] = message.message,
+    ),
+    JavaScriptChannel(
+      name: 'js_channel_3',
+      onMessageReceived: (JavaScriptMessage message) =>
+          _log['js_channel_3'] = message.message,
+    ),
+  };
+
+  tearDown(() {
+    _log.clear();
+  });
+
+  test('ctor should initialize with channels.', () {
+    final JavaScriptChannelRegistry registry =
+        JavaScriptChannelRegistry(_channels);
+
+    expect(registry.channels.length, 3);
+    for (final JavaScriptChannel channel in _channels) {
+      expect(registry.channels[channel.name], channel);
+    }
+  });
+
+  test('onJavaScriptChannelMessage should forward message on correct channel.',
+      () {
+    final JavaScriptChannelRegistry registry =
+        JavaScriptChannelRegistry(_channels);
+
+    registry.onJavaScriptChannelMessage(
+      'js_channel_2',
+      'test message on channel 2',
+    );
+
+    expect(
+        _log,
+        containsPair(
+          'js_channel_2',
+          'test message on channel 2',
+        ));
+  });
+
+  test(
+      'onJavaScriptChannelMessage should throw ArgumentError when message arrives on non-existing channel.',
+      () {
+    final JavaScriptChannelRegistry registry =
+        JavaScriptChannelRegistry(_channels);
+
+    expect(
+        () => registry.onJavaScriptChannelMessage(
+              'js_channel_4',
+              'test message on channel 2',
+            ),
+        throwsA(
+          isA<ArgumentError>().having((ArgumentError error) => error.message,
+              'message', 'No channel registered with name js_channel_4.'),
+        ));
+  });
+
+  test(
+      'updateJavaScriptChannelsFromSet should clear all channels when null is supplied.',
+      () {
+    final JavaScriptChannelRegistry registry =
+        JavaScriptChannelRegistry(_channels);
+
+    expect(registry.channels.length, 3);
+
+    registry.updateJavaScriptChannelsFromSet(null);
+
+    expect(registry.channels, isEmpty);
+  });
+
+  test('updateJavaScriptChannelsFromSet should update registry with new set.',
+      () {
+    final JavaScriptChannelRegistry registry =
+        JavaScriptChannelRegistry(_channels);
+
+    expect(registry.channels.length, 3);
+
+    final Set<JavaScriptChannel> newChannels = <JavaScriptChannel>{
+      JavaScriptChannel(
+        name: 'new_js_channel_1',
+        onMessageReceived: (JavaScriptMessage message) =>
+            _log['new_js_channel_1'] = message.message,
+      ),
+      JavaScriptChannel(
+        name: 'new_js_channel_2',
+        onMessageReceived: (JavaScriptMessage message) =>
+            _log['new_js_channel_2'] = message.message,
+      ),
+    };
+
+    registry.updateJavaScriptChannelsFromSet(newChannels);
+
+    expect(registry.channels.length, 2);
+    for (final JavaScriptChannel channel in newChannels) {
+      expect(registry.channels[channel.name], channel);
+    }
+  });
+}