add api impls

packages/webview_flutter/webview_flutter_wkwebview/lib/src/foundation/foundation_api_impls.dart

@@ -0,0 +1,134 @@
+// 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/foundation.dart';
+import 'package:flutter/services.dart';
+
+import '../common/instance_manager.dart';
+import '../common/web_kit.pigeon.dart';
+import 'foundation.dart';
+
+Iterable<NSKeyValueObservingOptionsEnumData>
+    _toNSKeyValueObservingOptionsEnumData(
+  Iterable<NSKeyValueObservingOptions> options,
+) {
+  return options.map<NSKeyValueObservingOptionsEnumData>((
+    NSKeyValueObservingOptions option,
+  ) {
+    late final NSKeyValueObservingOptionsEnum? value;
+    switch (option) {
+      case NSKeyValueObservingOptions.newValue:
+        value = NSKeyValueObservingOptionsEnum.newValue;
+        break;
+      case NSKeyValueObservingOptions.oldValue:
+        value = NSKeyValueObservingOptionsEnum.oldValue;
+        break;
+      case NSKeyValueObservingOptions.initialValue:
+        value = NSKeyValueObservingOptionsEnum.initialValue;
+        break;
+      case NSKeyValueObservingOptions.priorNotification:
+        value = NSKeyValueObservingOptionsEnum.priorNotification;
+        break;
+    }
+
+    return NSKeyValueObservingOptionsEnumData(value: value);
+  });
+}
+
+/// Handles initialization of Flutter APIs for the Foundation library.
+// TODO(bparrishMines): Add NSObjectFlutterApiImpl once the callback methods
+// are added.
+class FoundationFlutterApis {
+  /// Constructs a [FoundationFlutterApis].
+  @visibleForTesting
+  FoundationFlutterApis({
+    BinaryMessenger? binaryMessenger,
+    // ignore: avoid_unused_constructor_parameters
+    InstanceManager? instanceManager,
+  }) : _binaryMessenger = binaryMessenger;
+
+  static FoundationFlutterApis _instance = FoundationFlutterApis();
+
+  /// Sets the global instance containing the Flutter Apis for the Foundation library.
+  @visibleForTesting
+  static set instance(FoundationFlutterApis instance) {
+    _instance = instance;
+  }
+
+  /// Global instance containing the Flutter Apis for the Foundation library.
+  static FoundationFlutterApis get instance {
+    return _instance;
+  }
+
+  // ignore: unused_field
+  final BinaryMessenger? _binaryMessenger;
+  bool _hasBeenSetUp = false;
+
+  /// Ensures all the Flutter APIs have been set up to receive calls from native code.
+  void ensureSetUp() {
+    if (!_hasBeenSetUp) {
+      _hasBeenSetUp = true;
+    }
+  }
+}
+
+/// Host api implementation for [NSObject].
+@immutable
+class NSObjectHostApiImpl extends NSObjectHostApi {
+  /// Constructs an [NSObjectHostApiImpl].
+  NSObjectHostApiImpl({
+    this.binaryMessenger,
+    InstanceManager? instanceManager,
+  })  : instanceManager = instanceManager ?? NSObject.globalInstanceManager,
+        super(binaryMessenger: binaryMessenger);
+
+  /// Sends binary data across the Flutter platform barrier.
+  ///
+  /// If it is null, the default BinaryMessenger will be used which routes to
+  /// the host platform.
+  final BinaryMessenger? binaryMessenger;
+
+  /// Maintains instances stored to communicate with Objective-C objects.
+  final InstanceManager instanceManager;
+
+  /// Calls [addObserver] with the ids of the provided object instances.
+  Future<void> addObserverForInstances(
+    NSObject instance,
+    NSObject observer,
+    String keyPath,
+    Set<NSKeyValueObservingOptions> options,
+  ) {
+    return addObserver(
+      instanceManager.getIdentifier(instance)!,
+      instanceManager.getIdentifier(observer)!,
+      keyPath,
+      _toNSKeyValueObservingOptionsEnumData(options).toList(),
+    );
+  }
+
+  /// Calls [removeObserver] with the ids of the provided object instances.
+  Future<void> removeObserverForInstances(
+    NSObject instance,
+    NSObject observer,
+    String keyPath,
+  ) {
+    return removeObserver(
+      instanceManager.getIdentifier(instance)!,
+      instanceManager.getIdentifier(observer)!,
+      keyPath,
+    );
+  }
+
+  @override
+  int get hashCode {
+    return Object.hash(binaryMessenger, instanceManager);
+  }
+
+  @override
+  bool operator ==(Object other) {
+    return other is NSObjectHostApiImpl &&
+        binaryMessenger == other.binaryMessenger &&
+        instanceManager == other.instanceManager;
+  }
+}