105 lines
4.6 KiB
JavaScript
105 lines
4.6 KiB
JavaScript
import { isScheduler } from '../util/isScheduler';
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import { of } from './of';
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import { from } from './from';
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import { concatAll } from '../operators/concatAll';
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/* tslint:enable:max-line-length */
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/**
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* Creates an output Observable which sequentially emits all values from given
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* Observable and then moves on to the next.
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*
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* <span class="informal">Concatenates multiple Observables together by
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* sequentially emitting their values, one Observable after the other.</span>
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*
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* <img src="./img/concat.png" width="100%">
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*
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* `concat` joins multiple Observables together, by subscribing to them one at a time and
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* merging their results into the output Observable. You can pass either an array of
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* Observables, or put them directly as arguments. Passing an empty array will result
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* in Observable that completes immediately.
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*
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* `concat` will subscribe to first input Observable and emit all its values, without
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* changing or affecting them in any way. When that Observable completes, it will
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* subscribe to then next Observable passed and, again, emit its values. This will be
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* repeated, until the operator runs out of Observables. When last input Observable completes,
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* `concat` will complete as well. At any given moment only one Observable passed to operator
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* emits values. If you would like to emit values from passed Observables concurrently, check out
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* {@link merge} instead, especially with optional `concurrent` parameter. As a matter of fact,
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* `concat` is an equivalent of `merge` operator with `concurrent` parameter set to `1`.
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*
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* Note that if some input Observable never completes, `concat` will also never complete
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* and Observables following the one that did not complete will never be subscribed. On the other
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* hand, if some Observable simply completes immediately after it is subscribed, it will be
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* invisible for `concat`, which will just move on to the next Observable.
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*
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* If any Observable in chain errors, instead of passing control to the next Observable,
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* `concat` will error immediately as well. Observables that would be subscribed after
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* the one that emitted error, never will.
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*
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* If you pass to `concat` the same Observable many times, its stream of values
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* will be "replayed" on every subscription, which means you can repeat given Observable
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* as many times as you like. If passing the same Observable to `concat` 1000 times becomes tedious,
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* you can always use {@link repeat}.
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*
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* @example <caption>Concatenate a timer counting from 0 to 3 with a synchronous sequence from 1 to 10</caption>
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* var timer = Rx.Observable.interval(1000).take(4);
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* var sequence = Rx.Observable.range(1, 10);
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* var result = Rx.Observable.concat(timer, sequence);
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* result.subscribe(x => console.log(x));
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*
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* // results in:
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* // 0 -1000ms-> 1 -1000ms-> 2 -1000ms-> 3 -immediate-> 1 ... 10
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*
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*
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* @example <caption>Concatenate an array of 3 Observables</caption>
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* var timer1 = Rx.Observable.interval(1000).take(10);
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* var timer2 = Rx.Observable.interval(2000).take(6);
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* var timer3 = Rx.Observable.interval(500).take(10);
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* var result = Rx.Observable.concat([timer1, timer2, timer3]); // note that array is passed
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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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* // (Prints to console sequentially)
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* // -1000ms-> 0 -1000ms-> 1 -1000ms-> ... 9
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* // -2000ms-> 0 -2000ms-> 1 -2000ms-> ... 5
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* // -500ms-> 0 -500ms-> 1 -500ms-> ... 9
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*
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*
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* @example <caption>Concatenate the same Observable to repeat it</caption>
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* const timer = Rx.Observable.interval(1000).take(2);
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*
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* Rx.Observable.concat(timer, timer) // concating the same Observable!
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* .subscribe(
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* value => console.log(value),
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* err => {},
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* () => console.log('...and it is done!')
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* );
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*
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* // Logs:
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* // 0 after 1s
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* // 1 after 2s
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* // 0 after 3s
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* // 1 after 4s
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* // "...and it is done!" also after 4s
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*
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* @see {@link concatAll}
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* @see {@link concatMap}
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* @see {@link concatMapTo}
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*
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* @param {ObservableInput} input1 An input Observable to concatenate with others.
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* @param {ObservableInput} input2 An input Observable to concatenate with others.
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* More than one input Observables may be given as argument.
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* @param {Scheduler} [scheduler=null] An optional IScheduler to schedule each
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* Observable subscription on.
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* @return {Observable} All values of each passed Observable merged into a
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* single Observable, in order, in serial fashion.
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* @static true
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* @name concat
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* @owner Observable
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*/
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export function concat(...observables) {
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if (observables.length === 1 || (observables.length === 2 && isScheduler(observables[1]))) {
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return from(observables[0]);
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}
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return concatAll()(of(...observables));
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}
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//# sourceMappingURL=concat.js.map
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