[6a3a178] | 1 | import { Observable } from '../Observable';
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| 2 | import { map } from './map';
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| 3 | import { OperatorFunction } from '../types';
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| 4 |
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| 5 | /* tslint:disable:max-line-length */
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| 6 | export function pluck<T, K1 extends keyof T>(k1: K1): OperatorFunction<T, T[K1]>;
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| 7 | export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1]>(k1: K1, k2: K2): OperatorFunction<T, T[K1][K2]>;
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| 8 | export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2]>(k1: K1, k2: K2, k3: K3): OperatorFunction<T, T[K1][K2][K3]>;
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| 9 | export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2], K4 extends keyof T[K1][K2][K3]>(k1: K1, k2: K2, k3: K3, k4: K4): OperatorFunction<T, T[K1][K2][K3][K4]>;
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| 10 | export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2], K4 extends keyof T[K1][K2][K3], K5 extends keyof T[K1][K2][K3][K4]>(k1: K1, k2: K2, k3: K3, k4: K4, k5: K5): OperatorFunction<T, T[K1][K2][K3][K4][K5]>;
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| 11 | export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2], K4 extends keyof T[K1][K2][K3], K5 extends keyof T[K1][K2][K3][K4], K6 extends keyof T[K1][K2][K3][K4][K5]>(k1: K1, k2: K2, k3: K3, k4: K4, k5: K5, k6: K6): OperatorFunction<T, T[K1][K2][K3][K4][K5][K6]>;
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| 12 | export function pluck<T, R>(...properties: string[]): OperatorFunction<T, R>;
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| 13 | /* tslint:enable:max-line-length */
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| 14 |
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| 15 | /**
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| 16 | * Maps each source value (an object) to its specified nested property.
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| 17 | *
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| 18 | * <span class="informal">Like {@link map}, but meant only for picking one of
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| 19 | * the nested properties of every emitted object.</span>
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| 20 | *
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| 21 | * ![](pluck.png)
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| 22 | *
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| 23 | * Given a list of strings describing a path to an object property, retrieves
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| 24 | * the value of a specified nested property from all values in the source
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| 25 | * Observable. If a property can't be resolved, it will return `undefined` for
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| 26 | * that value.
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| 27 | *
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| 28 | * ## Example
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| 29 | * Map every click to the tagName of the clicked target element
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| 30 | * ```ts
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| 31 | * import { fromEvent } from 'rxjs';
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| 32 | * import { pluck } from 'rxjs/operators';
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| 33 | *
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| 34 | * const clicks = fromEvent(document, 'click');
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| 35 | * const tagNames = clicks.pipe(pluck('target', 'tagName'));
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| 36 | * tagNames.subscribe(x => console.log(x));
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| 37 | * ```
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| 38 | *
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| 39 | * @see {@link map}
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| 40 | *
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| 41 | * @param {...string} properties The nested properties to pluck from each source
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| 42 | * value (an object).
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| 43 | * @return {Observable} A new Observable of property values from the source values.
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| 44 | * @method pluck
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| 45 | * @owner Observable
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| 46 | */
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| 47 | export function pluck<T, R>(...properties: string[]): OperatorFunction<T, R> {
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| 48 | const length = properties.length;
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| 49 | if (length === 0) {
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| 50 | throw new Error('list of properties cannot be empty.');
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| 51 | }
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| 52 | return (source: Observable<T>) => map(plucker(properties, length))(source as any);
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| 53 | }
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| 54 |
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| 55 | function plucker(props: string[], length: number): (x: string) => any {
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| 56 | const mapper = (x: string) => {
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| 57 | let currentProp = x;
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| 58 | for (let i = 0; i < length; i++) {
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| 59 | const p = currentProp != null ? currentProp[props[i]] : undefined;
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| 60 | if (p !== void 0) {
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| 61 | currentProp = p;
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| 62 | } else {
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| 63 | return undefined;
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| 64 | }
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| 65 | }
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| 66 | return currentProp;
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| 67 | };
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| 68 |
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| 69 | return mapper;
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| 70 | }
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