feat(EventBus): 支持 beforeEmit, beforeOn, tag

src/utils/EventBus.test.ts

@@ -6,7 +6,7 @@ type Events = {
   error: (payload: { message: string }) => any
 }
 
-describe(EventBus.name, () => {
+describe('EventBus', () => {
   test('可订阅发布', () => {
     const bus = new EventBus<Events>()
     const enterCallback = jest.fn()
@@ -87,4 +87,85 @@ describe(EventBus.name, () => {
     const results = bus.emit('enter')
     expect(results).toEqual([1, 2])
   })
+
+  test('支持 beforeOn', () => {
+    const bus = new EventBus<Events>({
+      beforeOn: {
+        error(cb) {
+          cb.__EVENT_BUS_TAG__ = 200
+          return cb
+        },
+      },
+    })
+    const errorCallback = jest.fn().mockImplementation(() => 1)
+    const errorCallback2 = jest.fn().mockImplementation(() => 2)
+    bus.on('error', errorCallback)
+    bus.on('error', errorCallback2)
+    const results = bus.emit('error', { message: 'hello' })
+    expect(results).toEqual([1, 2])
+    expect(errorCallback).toBeCalled().toBeCalledTimes(1)
+    expect(errorCallback2).toBeCalled().toBeCalledTimes(1)
+    bus.off('error', 200)
+    const results2 = bus.emit('error', { message: 'hello2' })
+    expect(results2).toEqual([])
+    expect(errorCallback).toBeCalled().toBeCalledTimes(1)
+    expect(errorCallback2).toBeCalled().toBeCalledTimes(1)
+  })
+
+  test('支持 beforeEmit', () => {
+    const bus = new EventBus<Events>({
+      beforeEmit: {
+        error() {
+          this.emit({
+            name: 'success',
+          })
+        },
+      },
+    })
+    const errorCallback = jest.fn().mockImplementation(() => 1)
+    const errorCallback2 = jest.fn().mockImplementation(() => 2)
+    const successCallback = jest.fn().mockImplementation(() => 'x')
+    const successCallback2 = jest.fn().mockImplementation(() => 'y')
+    bus.on('error', errorCallback)
+    bus.on('error', errorCallback2)
+    bus.on('success', successCallback)
+    bus.on('success', successCallback2)
+    const results = bus.emit('error', { message: 'hello' })
+    expect(results).toEqual([1, 2])
+    expect(errorCallback).toBeCalled().toBeCalledTimes(1)
+    expect(errorCallback2).toBeCalled().toBeCalledTimes(1)
+    expect(successCallback).toBeCalled().toBeCalledTimes(1)
+    expect(successCallback2).toBeCalled().toBeCalledTimes(1)
+  })
+
+  test('支持按 tag emit', () => {
+    let i = 0
+    const bus = new EventBus<Events>({
+      beforeOn: {
+        error(cb) {
+          cb.__EVENT_BUS_TAG__ = i++
+          return cb
+        },
+      },
+    })
+    const errorCallback = jest.fn().mockImplementation(() => 1)
+    const errorCallback2 = jest.fn().mockImplementation(() => 2)
+    bus.on('error', errorCallback)
+    bus.on('error', errorCallback2)
+
+    const results = bus.emit('error', { message: 'hello' })
+    expect(results).toEqual([1, 2])
+    expect(errorCallback).toBeCalled().toBeCalledTimes(1)
+    expect(errorCallback2).toBeCalled().toBeCalledTimes(1)
+
+    const results2 = bus.emit({ name: 'error', tag: 0 }, { message: 'hello2' })
+    expect(results2).toEqual([1])
+    expect(errorCallback).toBeCalled().toBeCalledTimes(2)
+    expect(errorCallback2).toBeCalled().toBeCalledTimes(1)
+
+    const results3 = bus.emit({ name: 'error', tag: 1 }, { message: 'hello3' })
+    expect(results3).toEqual([2])
+    expect(errorCallback).toBeCalled().toBeCalledTimes(2)
+    expect(errorCallback2).toBeCalled().toBeCalledTimes(2)
+  })
 })

src/utils/EventBus.ts

@@ -1,8 +1,46 @@
+export type EventBusListenerTag = string | number
+
+export type EventBusListener<
+  TCallback extends (...args: any[]) => any = (...args: any[]) => any
+> = TCallback & {
+  __EVENT_BUS_TAG__?: EventBusListenerTag
+}
+
+export type EventBusOffListener = () => any
+
+export type EventBusListeners = Record<string, EventBusListener>
+
+export interface EventBusListenerDescriptor<
+  TListenerName extends keyof EventBusListeners
+> {
+  name: TListenerName
+  context?: any
+  tag?: EventBusListenerTag
+}
+
+export type EventBusBeforeOn<TListeners extends EventBusListeners> = {
+  [TListenerName in keyof TListeners]?: (
+    this: EventBus<TListeners>,
+    callback: EventBusListener<TListeners[TListenerName]>,
+  ) => TListeners[TListenerName]
+}
+
+export type EventBusBeforeEmit<TListeners extends EventBusListeners> = {
+  [TListenerName in keyof TListeners]?: (
+    this: EventBus<TListeners>,
+    context: any,
+  ) => any
+}
+
+export interface EventBusOptions<TListeners extends EventBusListeners> {
+  beforeOn?: EventBusBeforeOn<TListeners>
+  beforeEmit?: EventBusBeforeEmit<TListeners>
+}
+
 /**
  * 事件巴士，管理事件的发布与订阅。
  *
- * @public
- * @template TEvents 事件名称及其对应的回调描述
+ * @template TListeners 事件名称及其对应的回调描述
  * @example
  * ```typescript
  * const bus = new EventBus<{
@@ -13,12 +51,17 @@
  * // => 控制台输出: 提交成功
  * ```
  */
-export class EventBus<TEvents extends Record<string, (...args: any[]) => any>> {
+export class EventBus<TListeners extends EventBusListeners> {
+  /**
+   * 构造函数。
+   */
+  constructor(private options?: EventBusOptions<TListeners>) {}
+
   /**
    * 回调列表。
    */
   private callbacks: {
-    [Key in keyof TEvents]: Array<TEvents[Key]>
+    [TListenerName in keyof TListeners]: Array<TListeners[TListenerName]>
   } = Object.create(null)
 
   /**
@@ -28,13 +71,15 @@ export class EventBus<TEvents extends Record<string, (...args: any[]) => any>> {
    * @param callback 事件触发回调
    * @returns 返回取消订阅的函数
    */
-  on<TName extends keyof TEvents>(
-    eventName: TName,
-    callback: TEvents[TName],
-  ): () => any {
+  on<TListenerName extends keyof TListeners>(
+    eventName: TListenerName,
+    callback: TListeners[TListenerName],
+  ): EventBusOffListener {
     if (!this.callbacks[eventName]) {
       this.callbacks[eventName] = []
     }
+    callback =
+      this.options?.beforeOn?.[eventName]?.call(this, callback) ?? callback
     const index = this.callbacks[eventName].indexOf(callback)
     if (index === -1) {
       this.callbacks[eventName].push(callback)
@@ -49,14 +94,14 @@ export class EventBus<TEvents extends Record<string, (...args: any[]) => any>> {
    * @param callback 事件触发回调
    * @returns 返回取消订阅的函数
    */
-  once<TName extends keyof TEvents>(
-    eventName: TName,
-    callback: TEvents[TName],
-  ): () => any {
+  once<TListenerName extends keyof TListeners>(
+    eventName: TListenerName,
+    callback: TListeners[TListenerName],
+  ): EventBusOffListener {
     const off = this.on(eventName, ((...args) => {
       off()
       callback(...args)
-    }) as TEvents[TName])
+    }) as TListeners[TListenerName])
     return off
   }
 
@@ -66,14 +111,26 @@ export class EventBus<TEvents extends Record<string, (...args: any[]) => any>> {
    * @param eventName 事件名称
    * @param callback 事件触发回调
    */
-  off<TName extends keyof TEvents>(
-    eventName: TName,
-    callback?: TEvents[TName],
+  off<TListenerName extends keyof TListeners>(
+    eventName: TListenerName,
+    callbackOrTag?: TListeners[TListenerName] | string | number,
   ): void {
-    if (this.callbacks[eventName] && callback) {
-      const index = this.callbacks[eventName].indexOf(callback)
-      if (index > -1) {
-        this.callbacks[eventName].splice(index, 1)
+    if (this.callbacks[eventName] && callbackOrTag) {
+      if (typeof callbackOrTag === 'function') {
+        const index = this.callbacks[eventName].indexOf(callbackOrTag)
+        if (index > -1) {
+          this.callbacks[eventName].splice(index, 1)
+        }
+      } else {
+        let index = this.callbacks[eventName].length
+        while (index--) {
+          if (
+            this.callbacks[eventName][index].__EVENT_BUS_TAG__ != null &&
+            this.callbacks[eventName][index].__EVENT_BUS_TAG__ === callbackOrTag
+          ) {
+            this.callbacks[eventName].splice(index, 1)
+          }
+        }
       }
     } else {
       delete this.callbacks[eventName]
@@ -83,16 +140,40 @@ export class EventBus<TEvents extends Record<string, (...args: any[]) => any>> {
   /**
    * 发布事件。
    *
-   * @param eventName 事件名称
+   * @param eventNameAndContext 事件名称和上下文
    * @param args 传给事件回调的参数
    * @returns 返回各事件回调的返回结果组成的数组
    */
-  emit<TName extends keyof TEvents>(
-    eventName: TName,
-    ...args: Parameters<TEvents[TName]>
-  ): Array<ReturnType<TEvents[TName]>> {
-    return (this.callbacks[eventName] || []).map(callback => {
-      return callback(...args)
+  emit<TListenerName extends keyof TListeners>(
+    // @ts-ignore
+    eventName: TListenerName | EventBusListenerDescriptor<TListenerName>,
+    ...args: Parameters<TListeners[TListenerName]>
+  ): Array<ReturnType<TListeners[TListenerName]>> {
+    const {
+      name,
+      context,
+      tag,
+    }: {
+      name: TListenerName
+      context?: any
+      tag?: string | number
+    } =
+      typeof eventName === 'object'
+        ? eventName
+        : {
+            name: eventName,
+          }
+    let callbacks = this.callbacks[name] || []
+    if (tag != null) {
+      callbacks = callbacks.filter(
+        callback =>
+          callback.__EVENT_BUS_TAG__ != null &&
+          tag === callback.__EVENT_BUS_TAG__,
+      )
+    }
+    this.options?.beforeEmit?.[name]?.call(this, context)
+    return callbacks.map(callback => {
+      return callback.call(context, ...args)
     })
   }
 }