491f0cd08a
* Copyright headers 1 * Licence headers 2 * Copyright Headers 3 * Copyright Headers 4 * Copyright Headers 5 * Copyright Headers 6 * Copyright headers 7 * Add copyright headers for html and config file * Replace license files and update package.json * Update with CLA * lint
79 lines
2.5 KiB
TypeScript
79 lines
2.5 KiB
TypeScript
/*
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Copyright 2024 New Vector Ltd.
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Copyright 2020 The Matrix.org Foundation C.I.C.
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SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only
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Please see LICENSE files in the repository root for full details.
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*/
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import { logger } from "matrix-js-sdk/src/logger";
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import { IDestroyable } from "./IDestroyable";
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import { arrayFastClone } from "./arrays";
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export type WhenFn<T extends string | number> = (w: Whenable<T>) => void;
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/**
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* Whenables are a cheap way to have Observable patterns mixed with typical
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* usage of Promises, without having to tear down listeners or calls. Whenables
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* are intended to be used when a condition will be met multiple times and
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* the consumer needs to know *when* that happens.
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*/
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export abstract class Whenable<T extends string | number> implements IDestroyable {
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private listeners: { condition: T | null; fn: WhenFn<T> }[] = [];
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/**
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* Sets up a call to `fn` *when* the `condition` is met.
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* @param condition The condition to match.
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* @param fn The function to call.
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* @returns This.
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*/
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public when(condition: T, fn: WhenFn<T>): Whenable<T> {
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this.listeners.push({ condition, fn });
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return this;
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}
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/**
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* Sets up a call to `fn` *when* any of the `conditions` are met.
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* @param conditions The conditions to match.
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* @param fn The function to call.
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* @returns This.
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*/
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public whenAnyOf(conditions: T[], fn: WhenFn<T>): Whenable<T> {
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for (const condition of conditions) {
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this.when(condition, fn);
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}
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return this;
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}
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/**
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* Sets up a call to `fn` *when* any condition is met.
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* @param fn The function to call.
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* @returns This.
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*/
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public whenAnything(fn: WhenFn<T>): Whenable<T> {
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this.listeners.push({ condition: null, fn });
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return this;
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}
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/**
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* Notifies all the listeners of a given condition.
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* @param condition The new condition that has been met.
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*/
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protected notifyCondition(condition: T): void {
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const listeners = arrayFastClone(this.listeners); // clone just in case the handler modifies us
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for (const listener of listeners) {
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if (listener.condition === null || listener.condition === condition) {
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try {
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listener.fn(this);
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} catch (e) {
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logger.error(`Error calling whenable listener for ${condition}:`, e);
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}
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}
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}
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}
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public destroy(): void {
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this.listeners = [];
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}
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}
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