| {"version":3,"file":"cdk-observers.umd.min.js","sources":["../../src/cdk/observers/observe-content.ts"],"sourcesContent":["/**\n * @license\n * Copyright Google LLC All Rights Reserved.\n *\n * Use of this source code is governed by an MIT-style license that can be\n * found in the LICENSE file at https://angular.io/license\n */\n\nimport {coerceBooleanProperty, coerceNumberProperty, coerceElement} from '@angular/cdk/coercion';\nimport {\n AfterContentInit,\n Directive,\n ElementRef,\n EventEmitter,\n Injectable,\n Input,\n NgModule,\n NgZone,\n OnDestroy,\n Output,\n} from '@angular/core';\nimport {Observable, Subject, Subscription, Observer} from 'rxjs';\nimport {debounceTime} from 'rxjs/operators';\n\n/**\n * Factory that creates a new MutationObserver and allows us to stub it out in unit tests.\n * @docs-private\n */\n@Injectable({providedIn: 'root'})\nexport class MutationObserverFactory {\n create(callback: MutationCallback): MutationObserver | null {\n return typeof MutationObserver === 'undefined' ? null : new MutationObserver(callback);\n }\n}\n\n\n/** An injectable service that allows watching elements for changes to their content. */\n@Injectable({providedIn: 'root'})\nexport class ContentObserver implements OnDestroy {\n /** Keeps track of the existing MutationObservers so they can be reused. */\n private _observedElements = new Map<Element, {\n observer: MutationObserver | null,\n stream: Subject<MutationRecord[]>,\n count: number\n }>();\n\n constructor(private _mutationObserverFactory: MutationObserverFactory) {}\n\n ngOnDestroy() {\n this._observedElements.forEach((_, element) => this._cleanupObserver(element));\n }\n\n /**\n * Observe content changes on an element.\n * @param element The element to observe for content changes.\n */\n observe(element: Element): Observable<MutationRecord[]>;\n\n /**\n * Observe content changes on an element.\n * @param element The element to observe for content changes.\n */\n observe(element: ElementRef<Element>): Observable<MutationRecord[]>;\n\n observe(elementOrRef: Element | ElementRef<Element>): Observable<MutationRecord[]> {\n const element = coerceElement(elementOrRef);\n\n return new Observable((observer: Observer<MutationRecord[]>) => {\n const stream = this._observeElement(element);\n const subscription = stream.subscribe(observer);\n\n return () => {\n subscription.unsubscribe();\n this._unobserveElement(element);\n };\n });\n }\n\n /**\n * Observes the given element by using the existing MutationObserver if available, or creating a\n * new one if not.\n */\n private _observeElement(element: Element): Subject<MutationRecord[]> {\n if (!this._observedElements.has(element)) {\n const stream = new Subject<MutationRecord[]>();\n const observer = this._mutationObserverFactory.create(mutations => stream.next(mutations));\n if (observer) {\n observer.observe(element, {\n characterData: true,\n childList: true,\n subtree: true\n });\n }\n this._observedElements.set(element, {observer, stream, count: 1});\n } else {\n this._observedElements.get(element)!.count++;\n }\n return this._observedElements.get(element)!.stream;\n }\n\n /**\n * Un-observes the given element and cleans up the underlying MutationObserver if nobody else is\n * observing this element.\n */\n private _unobserveElement(element: Element) {\n if (this._observedElements.has(element)) {\n this._observedElements.get(element)!.count--;\n if (!this._observedElements.get(element)!.count) {\n this._cleanupObserver(element);\n }\n }\n }\n\n /** Clean up the underlying MutationObserver for the specified element. */\n private _cleanupObserver(element: Element) {\n if (this._observedElements.has(element)) {\n const {observer, stream} = this._observedElements.get(element)!;\n if (observer) {\n observer.disconnect();\n }\n stream.complete();\n this._observedElements.delete(element);\n }\n }\n}\n\n\n/**\n * Directive that triggers a callback whenever the content of\n * its associated element has changed.\n */\n@Directive({\n selector: '[cdkObserveContent]',\n exportAs: 'cdkObserveContent',\n})\nexport class CdkObserveContent implements AfterContentInit, OnDestroy {\n /** Event emitted for each change in the element's content. */\n @Output('cdkObserveContent') event = new EventEmitter<MutationRecord[]>();\n\n /**\n * Whether observing content is disabled. 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