64 lines
2.9 KiB
JavaScript
64 lines
2.9 KiB
JavaScript
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/** PURE_IMPORTS_START ._concatMap PURE_IMPORTS_END */
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import { concatMap } from './concatMap';
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/* tslint:enable:max-line-length */
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/**
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* Projects each source value to the same Observable which is merged multiple
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* times in a serialized fashion on the output Observable.
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*
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* <span class="informal">It's like {@link concatMap}, but maps each value
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* always to the same inner Observable.</span>
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*
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* <img src="./img/concatMapTo.png" width="100%">
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*
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* Maps each source value to the given Observable `innerObservable` regardless
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* of the source value, and then flattens those resulting Observables into one
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* single Observable, which is the output Observable. Each new `innerObservable`
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* instance emitted on the output Observable is concatenated with the previous
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* `innerObservable` instance.
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*
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* __Warning:__ if source values arrive endlessly and faster than their
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* corresponding inner Observables can complete, it will result in memory issues
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* as inner Observables amass in an unbounded buffer waiting for their turn to
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* be subscribed to.
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*
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* Note: `concatMapTo` is equivalent to `mergeMapTo` with concurrency parameter
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* set to `1`.
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*
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* @example <caption>For each click event, tick every second from 0 to 3, with no concurrency</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var result = clicks.concatMapTo(Rx.Observable.interval(1000).take(4));
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* result.subscribe(x => console.log(x));
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*
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* // Results in the following:
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* // (results are not concurrent)
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* // For every click on the "document" it will emit values 0 to 3 spaced
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* // on a 1000ms interval
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* // one click = 1000ms-> 0 -1000ms-> 1 -1000ms-> 2 -1000ms-> 3
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*
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* @see {@link concat}
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* @see {@link concatAll}
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* @see {@link concatMap}
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* @see {@link mergeMapTo}
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* @see {@link switchMapTo}
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*
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* @param {ObservableInput} innerObservable An Observable to replace each value from
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* the source Observable.
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* @param {function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any} [resultSelector]
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* A function to produce the value on the output Observable based on the values
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* and the indices of the source (outer) emission and the inner Observable
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* emission. The arguments passed to this function are:
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* - `outerValue`: the value that came from the source
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* - `innerValue`: the value that came from the projected Observable
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* - `outerIndex`: the "index" of the value that came from the source
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* - `innerIndex`: the "index" of the value from the projected Observable
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* @return {Observable} An observable of values merged together by joining the
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* passed observable with itself, one after the other, for each value emitted
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* from the source.
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* @method concatMapTo
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* @owner Observable
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*/
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export function concatMapTo(innerObservable, resultSelector) {
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return concatMap(function () { return innerObservable; }, resultSelector);
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}
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//# sourceMappingURL=concatMapTo.js.map
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