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[v3.0] Custom awaiting watch emitter (#4609)
* Use a custom watch emitter implementation * Add documentation * Improve coverage
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,48 +1,72 @@ | ||
| import { EventEmitter } from 'node:events'; | ||
| import { AwaitedEventListener, AwaitingEventEmitter } from '../rollup/types'; | ||
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| type PromiseReturn<T extends (...args: any) => any> = ( | ||
| ...args: Parameters<T> | ||
| ) => Promise<ReturnType<T>>; | ||
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| export class WatchEmitter< | ||
| T extends { [event: string]: (...args: any) => any } | ||
| > extends EventEmitter { | ||
| private awaitedHandlers: { | ||
| [K in keyof T]?: PromiseReturn<T[K]>[]; | ||
| export class WatchEmitter<T extends { [event: string]: (...args: any) => any }> | ||
| implements AwaitingEventEmitter<T> | ||
| { | ||
| private currentHandlers: { | ||
| [K in keyof T]?: AwaitedEventListener<T, K>[]; | ||
| } = Object.create(null); | ||
| private persistentHandlers: { | ||
| [K in keyof T]?: AwaitedEventListener<T, K>[]; | ||
| } = Object.create(null); | ||
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| constructor() { | ||
| super(); | ||
| // Allows more than 10 bundles to be watched without | ||
| // showing the `MaxListenersExceededWarning` to the user. | ||
| this.setMaxListeners(Infinity); | ||
| } | ||
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| // Will be overwritten by Rollup | ||
| async close(): Promise<void> {} | ||
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| emitAndAwait<K extends keyof T>( | ||
| event: K, | ||
| ...args: Parameters<T[K]> | ||
| ): Promise<ReturnType<T[K]>[]> { | ||
| this.emit(event as string, ...(args as any[])); | ||
| return Promise.all(this.getHandlers(event).map(handler => handler(...args))); | ||
| emit<K extends keyof T>(event: K, ...args: Parameters<T[K]>): Promise<unknown> { | ||
| return Promise.all( | ||
| this.getCurrentHandlers(event) | ||
| .concat(this.getPersistentHandlers(event)) | ||
| .map(handler => handler(...args)) | ||
| ); | ||
| } | ||
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| off<K extends keyof T>(event: K, listener: AwaitedEventListener<T, K>): this { | ||
| const listeners = this.persistentHandlers[event]; | ||
| if (listeners) { | ||
| // A hack stolen from "mitt": ">>> 0" does not change numbers >= 0, but -1 | ||
| // (which would remove the last array element if used unchanged) is turned | ||
| // into max_int, which is outside the array and does not change anything. | ||
| listeners.splice(listeners.indexOf(listener) >>> 0, 1); | ||
| } | ||
| return this; | ||
| } | ||
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| on<K extends keyof T>(event: K, listener: AwaitedEventListener<T, K>): this { | ||
| this.getPersistentHandlers(event).push(listener); | ||
| return this; | ||
| } | ||
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| onCurrentAwaited<K extends keyof T>( | ||
| event: K, | ||
| listener: (...args: Parameters<T[K]>) => Promise<ReturnType<T[K]>> | ||
| ): this { | ||
| this.getHandlers(event).push(listener); | ||
| onCurrentRun<K extends keyof T>(event: K, listener: AwaitedEventListener<T, K>): this { | ||
| this.getCurrentHandlers(event).push(listener); | ||
| return this; | ||
| } | ||
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| removeAwaited(): this { | ||
| this.awaitedHandlers = {}; | ||
| once<K extends keyof T>(event: K, listener: AwaitedEventListener<T, K>): this { | ||
| const selfRemovingListener: AwaitedEventListener<T, K> = (...args) => { | ||
| this.off(event, selfRemovingListener); | ||
| return listener(...args); | ||
| }; | ||
| this.on(event, selfRemovingListener); | ||
| return this; | ||
| } | ||
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| private getHandlers<K extends keyof T>(event: K): PromiseReturn<T[K]>[] { | ||
| return this.awaitedHandlers[event] || (this.awaitedHandlers[event] = []); | ||
| removeAllListeners(): this { | ||
| this.removeListenersForCurrentRun(); | ||
| this.persistentHandlers = Object.create(null); | ||
| return this; | ||
| } | ||
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| removeListenersForCurrentRun(): this { | ||
| this.currentHandlers = Object.create(null); | ||
| return this; | ||
| } | ||
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| private getCurrentHandlers<K extends keyof T>(event: K): AwaitedEventListener<T, K>[] { | ||
| return this.currentHandlers[event] || (this.currentHandlers[event] = []); | ||
| } | ||
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| private getPersistentHandlers<K extends keyof T>(event: K): AwaitedEventListener<T, K>[] { | ||
| return this.persistentHandlers[event] || (this.persistentHandlers[event] = []); | ||
| } | ||
| } |
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