32 lines
1.2 KiB
TypeScript
32 lines
1.2 KiB
TypeScript
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/*
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Copyright 2023 New Vector Ltd
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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 { useEffect, useRef } from "react";
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import { BehaviorSubject, Observable } from "rxjs";
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/**
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* React hook that creates an Observable from a changing value. The Observable
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* replays its current value upon subscription, emits whenever the value
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* changes, and completes when the component is unmounted.
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*/
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export function useObservable<T>(value: T): Observable<T> {
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const subject = useRef<BehaviorSubject<T>>();
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subject.current ??= new BehaviorSubject(value);
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if (value !== subject.current.value) subject.current.next(value);
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useEffect(() => subject.current!.complete(), []);
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return subject.current;
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}
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