86 lines
2.3 KiB
TypeScript
86 lines
2.3 KiB
TypeScript
/*
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Copyright 2020 Bruno Windels <bruno@windels.cloud>
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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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// we return undefined so you can reassign any member
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// that uses `member?: T` syntax in one statement.
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export type SubscriptionHandle = () => undefined;
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export abstract class BaseObservable<T> {
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protected _handlers: Set<T> = new Set<T>();
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onSubscribeFirst(): void {
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}
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onUnsubscribeLast(): void {
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}
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subscribe(handler: T): SubscriptionHandle {
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this._handlers.add(handler);
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if (this._handlers.size === 1) {
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this.onSubscribeFirst();
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}
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return (): undefined => {
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return this.unsubscribe(handler);
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};
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}
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unsubscribe(handler?: T): undefined {
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if (handler) {
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this._handlers.delete(handler);
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if (this._handlers.size === 0) {
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this.onUnsubscribeLast();
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}
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}
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return undefined;
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}
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unsubscribeAll(): void {
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if (this._handlers.size !== 0) {
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this._handlers.clear();
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this.onUnsubscribeLast();
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}
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}
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get hasSubscriptions(): boolean {
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return this._handlers.size !== 0;
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}
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// Add iterator over handlers here
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}
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// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
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export function tests() {
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class Collection extends BaseObservable<{}> {
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firstSubscribeCalls: number = 0;
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firstUnsubscribeCalls: number = 0;
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onSubscribeFirst(): void { this.firstSubscribeCalls += 1; }
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onUnsubscribeLast(): void { this.firstUnsubscribeCalls += 1; }
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}
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return {
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test_unsubscribe(assert): void {
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const c = new Collection();
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const unsubscribe = c.subscribe({});
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unsubscribe();
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assert.equal(c.firstSubscribeCalls, 1);
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assert.equal(c.firstUnsubscribeCalls, 1);
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}
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};
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}
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