62 lines
2.0 KiB
TypeScript
62 lines
2.0 KiB
TypeScript
// (C) Copyright 2015 Moodle Pty Ltd.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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import { EventEmitter } from '@angular/core';
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import { Observable, Subscription } from 'rxjs';
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/**
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* Subscribable object.
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*/
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type Subscribable<T> = EventEmitter<T> | Observable<T>;
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/**
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* Singleton with helpers to work with subscriptions.
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*/
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export class CoreSubscriptions {
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/**
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* Listen once to a subscribable object.
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*
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* @param subscribable Subscribable to listen to.
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* @param onSuccess Callback to run when the subscription is updated.
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* @param onError Callback to run when the an error happens.
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*/
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static once<T>(subscribable: Subscribable<T>, onSuccess: (value: T) => unknown, onError?: (error: unknown) => unknown): void {
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let unsubscribe = false;
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let subscription: Subscription | null = null;
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subscription = subscribable.subscribe(
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value => {
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// Subscription variable might not be set because we can receive a value immediately.
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unsubscribe = true;
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subscription?.unsubscribe();
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onSuccess(value);
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},
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error => {
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// Subscription variable might not be set because we can receive a value immediately.
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unsubscribe = true;
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subscription?.unsubscribe();
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onError && onError(error);
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},
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);
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if (unsubscribe) {
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subscription.unsubscribe();
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}
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}
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}
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