wehub-resource-sync
62 lines
1.7 KiB
TypeScript
62 lines
1.7 KiB
TypeScript
import type watcher from '@parcel/watcher'
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import { debounceAsync } from './concurrency-utils'
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import { EventEmitter } from './event-emitter'
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export type FileChangeHandler = (events: watcher.Event[]) => Promise<void>
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type EmptyObject = Record<never, never>
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type FileWatcherEvent = {
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error: unknown
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close: EmptyObject
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}
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type FileWatcherOptions = watcher.Options & {
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debounceMs?: number
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}
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/**
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* Wraps the Parcel file watcher to ensure errors can be catched in an async/await fashion
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*/
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export class FileWatcher {
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public static async watch(dir: string, fn: FileChangeHandler, opt?: FileWatcherOptions) {
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const eventEmitter = new EventEmitter<FileWatcherEvent>()
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let subscriptionHandler = async (err: Error | null, events: watcher.Event[]) => {
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if (err) {
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eventEmitter.emit('error', err)
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return
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}
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try {
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await fn(events)
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} catch (thrown) {
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eventEmitter.emit('error', thrown)
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}
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}
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if (opt?.debounceMs) {
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subscriptionHandler = debounceAsync(subscriptionHandler, opt.debounceMs)
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}
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const watcher = await import('@parcel/watcher')
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const subscription = await watcher.subscribe(dir, subscriptionHandler, opt)
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return new FileWatcher(subscription, eventEmitter)
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}
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private constructor(
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private _subscription: watcher.AsyncSubscription,
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private _errorEmitter: EventEmitter<FileWatcherEvent>
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) {}
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public async close() {
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await this._subscription.unsubscribe()
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this._errorEmitter.emit('close', {})
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}
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public wait = () =>
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new Promise((resolve, reject) => {
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this._errorEmitter.once('error', reject)
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this._errorEmitter.once('close', resolve)
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})
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}
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