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20e2081c5c
- **BREAKING:BUILD** underlying Lit 1 libraries updated to Lit 2 - This may break certain builds that are transitively relying on Lit 1 - If your Lit 1 components break due to this, make sure your `package.json` explicitly includes the latest Lit 1 versions of lit-html and lit-element or deduplicate your versions of Lit 1 with your bundler PiperOrigin-RevId: 396468826
65 lines
2.4 KiB
TypeScript
65 lines
2.4 KiB
TypeScript
/**
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* @license
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* Copyright 2018 Google LLC
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* SPDX-License-Identifier: Apache-2.0
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*/
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// Style preference for leading underscores.
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// tslint:disable:strip-private-property-underscore
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// tslint:disable:no-any
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import {PropertyValues, ReactiveElement} from '@lit/reactive-element';
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/**
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* Observer function type.
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*/
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export interface Observer {
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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(value: any, old: any): void;
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}
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type ReactiveElementClass = typeof ReactiveElement;
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interface ReactiveElementClassWithObservers extends ReactiveElementClass {
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// tslint:disable-next-line:enforce-name-casing
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_observers: Map<PropertyKey, Observer>;
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}
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/**
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* Specifies an observer callback that is run when the decorated property
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* changes. The observer receives the current and old value as arguments.
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*/
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export const observer = (observer: Observer) =>
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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(proto: any, propName: PropertyKey) => {
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// if we haven't wrapped `updated` in this class, do so
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if (!(proto.constructor as ReactiveElementClassWithObservers)
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._observers) {
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proto.constructor._observers = new Map<PropertyKey, Observer>();
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const userUpdated = proto.updated;
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proto.updated = function(
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this: ReactiveElement, changedProperties: PropertyValues) {
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userUpdated.call(this, changedProperties);
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changedProperties.forEach((v, k) => {
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const observers =
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(this.constructor as ReactiveElementClassWithObservers)
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._observers;
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const observer = observers.get(k);
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if (observer !== undefined) {
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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observer.call(this, (this as any)[k], v);
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}
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});
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};
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// clone any existing observers (superclasses)
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// eslint-disable-next-line no-prototype-builtins
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} else if (!proto.constructor.hasOwnProperty('_observers')) {
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const observers = proto.constructor._observers;
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proto.constructor._observers = new Map();
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observers.forEach(
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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(v: any, k: PropertyKey) => proto.constructor._observers.set(k, v));
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}
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// set this method
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proto.constructor._observers.set(propName, observer);
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};
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