Separate Package for @react-native/event-emitter

Libraries/vendor/emitter/EventEmitter.js

@@ -8,139 +8,11 @@
  * @format
  */
 
-export interface EventSubscription {
-  remove(): void;
-}
-
-export interface IEventEmitter<TEventToArgsMap: {...}> {
-  addListener<TEvent: $Keys<TEventToArgsMap>>(
-    eventType: TEvent,
-    listener: (...args: $ElementType<TEventToArgsMap, TEvent>) => mixed,
-    context?: mixed,
-  ): EventSubscription;
-
-  emit<TEvent: $Keys<TEventToArgsMap>>(
-    eventType: TEvent,
-    ...args: $ElementType<TEventToArgsMap, TEvent>
-  ): void;
-
-  removeAllListeners<TEvent: $Keys<TEventToArgsMap>>(eventType?: ?TEvent): void;
-
-  listenerCount<TEvent: $Keys<TEventToArgsMap>>(eventType: TEvent): number;
-}
-
-interface Registration<TArgs> {
-  +context: mixed;
-  +listener: (...args: TArgs) => mixed;
-  +remove: () => void;
-}
-
-type Registry<TEventToArgsMap: {...}> = $ObjMap<
-  TEventToArgsMap,
-  <TArgs>(TArgs) => Set<Registration<TArgs>>,
->;
-
-/**
- * EventEmitter manages listeners and publishes events to them.
- *
- * EventEmitter accepts a single type parameter that defines the valid events
- * and associated listener argument(s).
- *
- * @example
- *
- *   const emitter = new EventEmitter<{
- *     success: [number, string],
- *     error: [Error],
- *   }>();
- *
- *   emitter.on('success', (statusCode, responseText) => {...});
- *   emitter.emit('success', 200, '...');
- *
- *   emitter.on('error', error => {...});
- *   emitter.emit('error', new Error('Resource not found'));
- *
- */
-export default class EventEmitter<TEventToArgsMap: {...}>
-  implements IEventEmitter<TEventToArgsMap>
-{
-  _registry: Registry<TEventToArgsMap> = {};
-
-  /**
-   * Registers a listener that is called when the supplied event is emitted.
-   * Returns a subscription that has a `remove` method to undo registration.
-   */
-  addListener<TEvent: $Keys<TEventToArgsMap>>(
-    eventType: TEvent,
-    listener: (...args: $ElementType<TEventToArgsMap, TEvent>) => mixed,
-    context: mixed,
-  ): EventSubscription {
-    const registrations = allocate(this._registry, eventType);
-    const registration: Registration<$ElementType<TEventToArgsMap, TEvent>> = {
-      context,
-      listener,
-      remove(): void {
-        registrations.delete(registration);
-      },
-    };
-    registrations.add(registration);
-    return registration;
-  }
-
-  /**
-   * Emits the supplied event. Additional arguments supplied to `emit` will be
-   * passed through to each of the registered listeners.
-   *
-   * If a listener modifies the listeners registered for the same event, those
-   * changes will not be reflected in the current invocation of `emit`.
-   */
-  emit<TEvent: $Keys<TEventToArgsMap>>(
-    eventType: TEvent,
-    ...args: $ElementType<TEventToArgsMap, TEvent>
-  ): void {
-    const registrations: ?Set<
-      Registration<$ElementType<TEventToArgsMap, TEvent>>,
-    > = this._registry[eventType];
-    if (registrations != null) {
-      for (const registration of [...registrations]) {
-        registration.listener.apply(registration.context, args);
-      }
-    }
-  }
-
-  /**
-   * Removes all registered listeners.
-   */
-  removeAllListeners<TEvent: $Keys<TEventToArgsMap>>(
-    eventType?: ?TEvent,
-  ): void {
-    if (eventType == null) {
-      this._registry = {};
-    } else {
-      delete this._registry[eventType];
-    }
-  }
-
-  /**
-   * Returns the number of registered listeners for the supplied event.
-   */
-  listenerCount<TEvent: $Keys<TEventToArgsMap>>(eventType: TEvent): number {
-    const registrations: ?Set<Registration<mixed>> = this._registry[eventType];
-    return registrations == null ? 0 : registrations.size;
-  }
-}
-
-function allocate<
-  TEventToArgsMap: {...},
-  TEvent: $Keys<TEventToArgsMap>,
-  TEventArgs: $ElementType<TEventToArgsMap, TEvent>,
->(
-  registry: Registry<TEventToArgsMap>,
-  eventType: TEvent,
-): Set<Registration<TEventArgs>> {
-  let registrations: ?Set<Registration<TEventArgs>> = registry[eventType];
-  if (registrations == null) {
-    registrations = new Set();
-    registry[eventType] = registrations;
-  }
-  return registrations;
-}
+import type {
+  EventSubscription,
+  IEventEmitter,
+} from '@react-native/event-emitter';
+import EventEmitter from '@react-native/event-emitter';
+
+export type {EventSubscription, IEventEmitter};
+export default EventEmitter;

package.json

@@ -108,6 +108,7 @@
     "@react-native-community/cli-platform-android": "^9.0.0-alpha.10",
     "@react-native-community/cli-platform-ios": "^9.0.0-alpha.10",
     "@react-native/assets": "1.0.0",
+    "@react-native/event-emitter": "^0.71.0",
     "@react-native/normalize-color": "2.0.0",
     "@react-native/polyfills": "2.0.0",
     "abort-controller": "^3.0.0",
@@ -139,7 +140,8 @@
     "flow-bin": "^0.184.0",
     "hermes-eslint": "0.8.0",
     "react": "18.2.0",
-    "react-test-renderer": "^18.2.0"
+    "react-test-renderer": "^18.2.0",
+    "typescript": "^4.7.4"
   },
   "codegenConfig": {
     "libraries": [

packages/event-emitter/.babelrc

@@ -0,0 +1,3 @@
+{
+  "presets": ["@babel/preset-flow"]
+}

packages/event-emitter/README.md

@@ -0,0 +1,10 @@
+# @react-native/event-emitter
+
+`@react-native/event-emitter` is an event library used by React Native that is
+published as an independent package so it can also be used by applications.
+
+Consult the included type definitions for usage instructions.
+
+## License
+
+`idx` is [MIT licensed](./LICENSE).

packages/event-emitter/lib/EventEmitter.d.ts

@@ -0,0 +1,83 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+export interface EventSubscription {
+  remove(): void;
+}
+
+export interface IEventEmitter<TEventToArgsMap extends {[eventType: string]: unknown[]}> {
+  addListener<TEvent extends keyof TEventToArgsMap>(
+    eventType: TEvent,
+    listener: (...args: TEventToArgsMap[TEvent]) => void,
+    context?: unknown,
+  ): EventSubscription;
+
+  emit<TEvent extends keyof TEventToArgsMap>(
+    eventType: TEvent,
+    ...args: TEventToArgsMap[TEvent]
+  ): void;
+
+  removeAllListeners<TEvent extends keyof TEventToArgsMap>(eventType?: TEvent | null): void;
+
+  listenerCount<TEvent extends keyof TEventToArgsMap>(eventType: TEvent): number;
+}
+
+/**
+ * EventEmitter manages listeners and publishes events to them.
+ *
+ * EventEmitter accepts a single type parameter that defines the valid events
+ * and associated listener argument(s).
+ *
+ * @example
+ *
+ *   const emitter = new EventEmitter<{
+ *     success: [number, string],
+ *     error: [Error],
+ *   }>();
+ *
+ *   emitter.on('success', (statusCode, responseText) => {...});
+ *   emitter.emit('success', 200, '...');
+ *
+ *   emitter.on('error', error => {...});
+ *   emitter.emit('error', new Error('Resource not found'));
+ *
+ */
+export default class EventEmitter<TEventToArgsMap extends {[eventType: string]: unknown[]}> implements IEventEmitter<TEventToArgsMap> {
+  /**
+   * Registers a listener that is called when the supplied event is emitted.
+   * Returns a subscription that has a `remove` method to undo registration.
+   */
+  addListener<TEvent extends keyof TEventToArgsMap>(
+    eventType: TEvent,
+    listener: (...args: TEventToArgsMap[TEvent]) => void,
+    context?: unknown,
+  ): EventSubscription;
+
+  /**
+   * Emits the supplied event. Additional arguments supplied to `emit` will be
+   * passed through to each of the registered listeners.
+   *
+   * If a listener modifies the listeners registered for the same event, those
+   * changes will not be reflected in the current invocation of `emit`.
+   */
+  emit<TEvent extends keyof TEventToArgsMap>(
+    eventType: TEvent,
+    ...args: TEventToArgsMap[TEvent]
+  ): void;
+
+  /**
+   * Removes all registered listeners.
+   */
+  removeAllListeners<TEvent extends keyof TEventToArgsMap>(eventType?: TEvent | null): void;
+
+  /**
+   * Returns the number of registered listeners for the supplied event.
+   */
+  listenerCount<TEvent extends keyof TEventToArgsMap>(eventType: TEvent): number;
+}

packages/event-emitter/lib/EventEmitter.js

@@ -0,0 +1,98 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ *
+ * @format
+ */
+
+/**
+ * EventEmitter manages listeners and publishes events to them.
+ *
+ * EventEmitter accepts a single type parameter that defines the valid events
+ * and associated listener argument(s).
+ *
+ * @example
+ *
+ *   const emitter = new EventEmitter<{
+ *     success: [number, string],
+ *     error: [Error],
+ *   }>();
+ *
+ *   emitter.on('success', (statusCode, responseText) => {...});
+ *   emitter.emit('success', 200, '...');
+ *
+ *   emitter.on('error', error => {...});
+ *   emitter.emit('error', new Error('Resource not found'));
+ *
+ */
+export default class EventEmitter {
+  _registry = {};
+  /**
+   * Registers a listener that is called when the supplied event is emitted.
+   * Returns a subscription that has a `remove` method to undo registration.
+   */
+
+  addListener(eventType, listener, context) {
+    const registrations = allocate(this._registry, eventType);
+    const registration = {
+      context,
+      listener,
+
+      remove() {
+        registrations.delete(registration);
+      },
+    };
+    registrations.add(registration);
+    return registration;
+  }
+  /**
+   * Emits the supplied event. Additional arguments supplied to `emit` will be
+   * passed through to each of the registered listeners.
+   *
+   * If a listener modifies the listeners registered for the same event, those
+   * changes will not be reflected in the current invocation of `emit`.
+   */
+
+  emit(eventType, ...args) {
+    const registrations = this._registry[eventType];
+
+    if (registrations != null) {
+      for (const registration of [...registrations]) {
+        registration.listener.apply(registration.context, args);
+      }
+    }
+  }
+  /**
+   * Removes all registered listeners.
+   */
+
+  removeAllListeners(eventType) {
+    if (eventType == null) {
+      this._registry = {};
+    } else {
+      delete this._registry[eventType];
+    }
+  }
+  /**
+   * Returns the number of registered listeners for the supplied event.
+   */
+
+  listenerCount(eventType) {
+    const registrations = this._registry[eventType];
+    return registrations == null ? 0 : registrations.size;
+  }
+}
+
+function allocate(registry, eventType) {
+  let registrations = registry[eventType];
+
+  if (registrations == null) {
+    registrations = new Set();
+    registry[eventType] = registrations;
+  }
+
+  return registrations;
+}