47877ba2da
* Switch to importing TypedEventEmitter from main js-sdk export * Switch to importing js-sdk/matrix in cypress * Remove duplicated imports * Fix lint:js-fix to run prettier last otherwise ESLint --fix may cause a mess * Add lint rule * Fix cypress-axe import * Fix cypress-axe import
103 lines
3.3 KiB
TypeScript
103 lines
3.3 KiB
TypeScript
/*
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Copyright 2019 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import { useRef, useEffect, useState, useCallback } from "react";
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import { ListenerMap, TypedEventEmitter } from "matrix-js-sdk/src/matrix";
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import type { EventEmitter } from "events";
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type Handler = (...args: any[]) => void;
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export function useTypedEventEmitter<Events extends string, Arguments extends ListenerMap<Events>>(
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emitter: TypedEventEmitter<Events, Arguments> | undefined,
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eventName: Events,
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handler: Handler,
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): void {
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useEventEmitter(emitter, eventName, handler);
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}
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/**
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* Hook to wrap an EventEmitter on and off in hook lifecycle
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*/
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export function useEventEmitter(emitter: EventEmitter | undefined, eventName: string | symbol, handler: Handler): void {
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// Create a ref that stores handler
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const savedHandler = useRef(handler);
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// Update ref.current value if handler changes.
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useEffect(() => {
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savedHandler.current = handler;
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}, [handler]);
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useEffect(
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() => {
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// allow disabling this hook by passing a falsy emitter
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if (!emitter) return;
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// Create event listener that calls handler function stored in ref
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const eventListener = (...args: any[]): void => savedHandler.current(...args);
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// Add event listener
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emitter.on(eventName, eventListener);
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// Remove event listener on cleanup
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return () => {
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emitter.off(eventName, eventListener);
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};
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},
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[eventName, emitter], // Re-run if eventName or emitter changes
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);
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}
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type Mapper<T> = (...args: any[]) => T;
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/**
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* {@link useEventEmitterState}
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*/
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export function useTypedEventEmitterState<T, Events extends string, Arguments extends ListenerMap<Events>>(
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emitter: TypedEventEmitter<Events, Arguments> | undefined,
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eventName: Events,
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fn: Mapper<T>,
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): T {
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return useEventEmitterState<T>(emitter, eventName, fn);
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}
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/**
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* Creates a state, that can be updated by events.
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*
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* @param emitter The emitter sending the event
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* @param eventName Event name to listen for
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* @param fn The callback function, that should return the state value.
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* It should have the signature of the event callback, except that all parameters are optional.
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* If the params are not set, a default value for the state should be returned.
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* @returns State
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*/
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export function useEventEmitterState<T>(
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emitter: EventEmitter | undefined,
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eventName: string | symbol,
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fn: Mapper<T>,
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): T {
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const [value, setValue] = useState<T>(fn);
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const handler = useCallback(
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(...args: any[]) => {
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setValue(fn(...args));
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},
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[fn],
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);
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// re-run when the emitter changes
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useEffect(handler, [emitter]); // eslint-disable-line react-hooks/exhaustive-deps
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useEventEmitter(emitter, eventName, handler);
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return value;
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}
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