89 lines
2.0 KiB
JavaScript
89 lines
2.0 KiB
JavaScript
import { EventEmitter } from "node:events";
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/**
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* This class emits events asynchronously.
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*
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* Note that Eleventy has two separate event emitter instances it uses:
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* 1. a userland one (UserConfig.js)
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* 2. a global one for internals (EventBus.js)
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*/
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class AsyncEventEmitter extends EventEmitter {
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#handlerMode = "parallel";
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// TypeScript slop
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constructor(...args) {
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super(...args);
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}
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reset() {
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// `eleventy#` event type listeners are removed at the start of each build (singletons)
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for (let type of this.eventNames()) {
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if (typeof type === "string" && type.startsWith("eleventy#")) {
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this.removeAllListeners(type);
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}
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}
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}
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/**
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* @param {string} type - The event name to emit.
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* @param {...*} args - Additional arguments that get passed to listeners.
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* @returns {Promise} - Promise resolves once all listeners were invoked
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*/
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/** @ts-expect-error */
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async emit(type, ...args) {
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let listeners = this.listeners(type);
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if (listeners.length === 0) {
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return [];
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}
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if (this.#handlerMode == "sequential") {
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const result = [];
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for (const listener of listeners) {
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const returnValue = await listener.apply(this, args);
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result.push(returnValue);
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}
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return result;
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} else {
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return Promise.all(
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listeners.map((listener) => {
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return listener.apply(this, args);
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}),
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);
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}
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}
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/**
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* @param {string} type - The event name to emit.
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* @param {...*} args - Additional lazy-executed function arguments that get passed to listeners.
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* @returns {Promise} - Promise resolves once all listeners were invoked
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*/
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async emitLazy(type, ...args) {
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let listeners = this.listeners(type);
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if (listeners.length === 0) {
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return [];
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}
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let argsMap = [];
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for (let arg of args) {
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if (typeof arg === "function") {
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let r = arg();
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if (r instanceof Promise) {
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r = await r;
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}
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argsMap.push(r);
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} else {
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argsMap.push(arg);
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}
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}
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return this.emit.call(this, type, ...argsMap);
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}
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setHandlerMode(mode) {
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this.#handlerMode = mode;
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}
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}
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export default AsyncEventEmitter;
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