87 lines
2.8 KiB
TypeScript
87 lines
2.8 KiB
TypeScript
/*
|
|
Copyright 2020 The Matrix.org Foundation C.I.C.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
import { logger } from "matrix-js-sdk/src/logger";
|
|
|
|
import { IDestroyable } from "./IDestroyable";
|
|
import { arrayFastClone } from "./arrays";
|
|
|
|
export type WhenFn<T> = (w: Whenable<T>) => void;
|
|
|
|
/**
|
|
* Whenables are a cheap way to have Observable patterns mixed with typical
|
|
* usage of Promises, without having to tear down listeners or calls. Whenables
|
|
* are intended to be used when a condition will be met multiple times and
|
|
* the consumer needs to know *when* that happens.
|
|
*/
|
|
export abstract class Whenable<T> implements IDestroyable {
|
|
private listeners: {condition: T | null, fn: WhenFn<T>}[] = [];
|
|
|
|
/**
|
|
* Sets up a call to `fn` *when* the `condition` is met.
|
|
* @param condition The condition to match.
|
|
* @param fn The function to call.
|
|
* @returns This.
|
|
*/
|
|
public when(condition: T, fn: WhenFn<T>): Whenable<T> {
|
|
this.listeners.push({ condition, fn });
|
|
return this;
|
|
}
|
|
|
|
/**
|
|
* Sets up a call to `fn` *when* any of the `conditions` are met.
|
|
* @param conditions The conditions to match.
|
|
* @param fn The function to call.
|
|
* @returns This.
|
|
*/
|
|
public whenAnyOf(conditions: T[], fn: WhenFn<T>): Whenable<T> {
|
|
for (const condition of conditions) {
|
|
this.when(condition, fn);
|
|
}
|
|
return this;
|
|
}
|
|
|
|
/**
|
|
* Sets up a call to `fn` *when* any condition is met.
|
|
* @param fn The function to call.
|
|
* @returns This.
|
|
*/
|
|
public whenAnything(fn: WhenFn<T>): Whenable<T> {
|
|
this.listeners.push({ condition: null, fn });
|
|
return this;
|
|
}
|
|
|
|
/**
|
|
* Notifies all the listeners of a given condition.
|
|
* @param condition The new condition that has been met.
|
|
*/
|
|
protected notifyCondition(condition: T) {
|
|
const listeners = arrayFastClone(this.listeners); // clone just in case the handler modifies us
|
|
for (const listener of listeners) {
|
|
if (listener.condition === null || listener.condition === condition) {
|
|
try {
|
|
listener.fn(this);
|
|
} catch (e) {
|
|
logger.error(`Error calling whenable listener for ${condition}:`, e);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
public destroy() {
|
|
this.listeners = [];
|
|
}
|
|
}
|