53 lines
1.7 KiB
TypeScript
53 lines
1.7 KiB
TypeScript
/**
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* @license
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* Copyright (C) 2020 The Android Open Source Project
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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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*/
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import {LitElement} from 'lit-element';
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import {Observable, Subject} from 'rxjs';
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import {takeUntil} from 'rxjs/operators';
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/**
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* Base class for Gerrit's lit-elements.
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*
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* Adds basic functionality that we want to have available in all Gerrit's
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* components.
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*/
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export abstract class GrLitElement extends LitElement {
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disconnected$ = new Subject();
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/**
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* Hooks up an element property with an observable. Apart from subscribing it
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* makes sure that you are unsubscribed when the component is disconnected.
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* And it requests a template check when a new value comes in.
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*
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* Should be called from connectedCallback() such that you will be
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* re-subscribed when the component is re-connected.
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*
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* TODO: Maybe distinctUntilChanged should be applied to obs$?
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*/
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subscribe<Key extends keyof this>(prop: Key, obs$: Observable<this[Key]>) {
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obs$.pipe(takeUntil(this.disconnected$)).subscribe(value => {
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const oldValue = this[prop];
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this[prop] = value;
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this.requestUpdate(prop, oldValue);
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});
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}
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disconnectedCallback() {
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this.disconnected$.next();
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super.disconnectedCallback();
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}
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}
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