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- import { OperatorFunction, MonoTypeOperatorFunction, TruthyTypesOf } from '../types';
- import { operate } from '../util/lift';
- import { createOperatorSubscriber } from './OperatorSubscriber';
- export function takeWhile<T>(predicate: BooleanConstructor, inclusive: true): MonoTypeOperatorFunction<T>;
- export function takeWhile<T>(predicate: BooleanConstructor, inclusive: false): OperatorFunction<T, TruthyTypesOf<T>>;
- export function takeWhile<T>(predicate: BooleanConstructor): OperatorFunction<T, TruthyTypesOf<T>>;
- export function takeWhile<T, S extends T>(predicate: (value: T, index: number) => value is S): OperatorFunction<T, S>;
- export function takeWhile<T, S extends T>(predicate: (value: T, index: number) => value is S, inclusive: false): OperatorFunction<T, S>;
- export function takeWhile<T>(predicate: (value: T, index: number) => boolean, inclusive?: boolean): MonoTypeOperatorFunction<T>;
- /**
- * Emits values emitted by the source Observable so long as each value satisfies
- * the given `predicate`, and then completes as soon as this `predicate` is not
- * satisfied.
- *
- * <span class="informal">Takes values from the source only while they pass the
- * condition given. When the first value does not satisfy, it completes.</span>
- *
- * 
- *
- * `takeWhile` subscribes and begins mirroring the source Observable. Each value
- * emitted on the source is given to the `predicate` function which returns a
- * boolean, representing a condition to be satisfied by the source values. The
- * output Observable emits the source values until such time as the `predicate`
- * returns false, at which point `takeWhile` stops mirroring the source
- * Observable and completes the output Observable.
- *
- * ## Example
- *
- * Emit click events only while the clientX property is greater than 200
- *
- * ```ts
- * import { fromEvent, takeWhile } from 'rxjs';
- *
- * const clicks = fromEvent<PointerEvent>(document, 'click');
- * const result = clicks.pipe(takeWhile(ev => ev.clientX > 200));
- * result.subscribe(x => console.log(x));
- * ```
- *
- * @see {@link take}
- * @see {@link takeLast}
- * @see {@link takeUntil}
- * @see {@link skip}
- *
- * @param predicate A function that evaluates a value emitted by the source
- * Observable and returns a boolean. Also takes the (zero-based) index as the
- * second argument.
- * @param inclusive When set to `true` the value that caused `predicate` to
- * return `false` will also be emitted.
- * @return A function that returns an Observable that emits values from the
- * source Observable so long as each value satisfies the condition defined by
- * the `predicate`, then completes.
- */
- export function takeWhile<T>(predicate: (value: T, index: number) => boolean, inclusive = false): MonoTypeOperatorFunction<T> {
- return operate((source, subscriber) => {
- let index = 0;
- source.subscribe(
- createOperatorSubscriber(subscriber, (value) => {
- const result = predicate(value, index++);
- (result || inclusive) && subscriber.next(value);
- !result && subscriber.complete();
- })
- );
- });
- }
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