@rx-angular/state/selections/lib/operators/selectSlice.d.ts

@rx-angular/state is a light-weight, flexible, strongly typed and tested tool dedicated to reduce the complexity of managing component state and side effects in angular

import { OperatorFunction } from 'rxjs';
import { KeyCompareMap, PickSlice } from '../interfaces/index';
/**
 * @description
 *
 * Returns an Observable that emits only the provided `keys` emitted by the source Observable. Each key will get
 * filtered to only emit _defined_ values as well as checked for distinct emissions.
 * Comparison will be done for each set key in the `keys` array.
 *
 * `selectSlice` will only emit _valid_ selections. A selection is _valid_ if every
 * selected key exists and is defined in the source Observable. This ensures that the `selectSlice`
 * operator will always return a complete slice with all values defined.
 *
 * You can fine grain your distinct checks by providing a `KeyCompareMap` with those keys you want to compute
 * explicitly different
 *
 * @example
 *
 * // An example with a custom comparison applied to each key
 * import { of } from 'rxjs';
 * import { selectSlice } from 'rx-angular/state';
 *
 *
 * const state$: Observable<MyState> = of(
 *  { title: 'myTitle', panelOpen: true},
 *  { title: 'myTitle2', panelOpen: true},
 *  { title: 'newTitle', panelOpen: true},
 *  { title: 'newTitle', panelOpen: false}
 * )
 * .pipe(
 *     selectSlice(['title', 'panelOpen']),
 *   )
 *   .subscribe(x => console.log(x));
 *
 * // displays:
 * //  { title: 'myTitle', panelOpen: true },
 * //  { title: 'myTitle2', panelOpen: true },
 * //  { title: 'newTitle', panelOpen: true },
 * //  { title: 'newTitle', panelOpen: false }
 *
 * @example
 *
 * import { of, Observable } from 'rxjs';
 * import { tap } from 'rxjs/operators';
 * import { selectSlice } from 'rx-angular/state';
 *
 * interface MyState {
 *    title: string;
 *    items: string[];
 *    panelOpen: boolean;
 * }
 * // Select items and title.
 * // apply custom compare logic for the items array
 * const customComparison: KeyCompareMap<MyState> = {
 *   items: (oldItems, newItems) => compareItems(oldItems, newItems)
 * };
 * const state$: Observable<MyState> = of(
 * { title: 'myTitle', items: ['foo', 'bar'], panelOpen: true },
 * { title: 'myTitle', items: ['foo', 'bar'], panelOpen: false },
 * { title: 'nextTitle', items: ['foo', 'baR'], panelOpen: true },
 * { title: 'nextTitle', items: ['fooRz', 'boo'], panelOpen: false },
 * );
 * const slice$ = state$.pipe(selectSlice(['title', 'items'], customComparison), tap(console.log)).subscribe();
 *
 * // displays:
 * // { title: 'myTitle', items: ['foo', 'bar'] }
 * // { title: 'nextTitle', items: ['foo', 'baR'] }
 * // { title: 'nextTitle', items: ['fooRz', 'boo'] }
 *
 * @param {(K)[]} keys - the array of keys which should be selected
 * @param {KeyCompareMap<{ [P in K]: T[P] }>} [keyCompareMap] Optional KeyCompareMap to provide custom compare logic
 * for some the keys
 * @docsPage selectSlice
 * @docsCategory operators
 */
export declare function selectSlice<T extends object, K extends keyof T>(keys: K[], keyCompareMap?: KeyCompareMap<{
    [P in K]: T[P];
}>): OperatorFunction<T, PickSlice<T, K>>;
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