50 lines
2.3 KiB
JavaScript
50 lines
2.3 KiB
JavaScript
import { not } from '../util/not';
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import { filter } from './filter';
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/**
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* Splits the source Observable into two, one with values that satisfy a
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* predicate, and another with values that don't satisfy the predicate.
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*
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* <span class="informal">It's like {@link filter}, but returns two Observables:
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* one like the output of {@link filter}, and the other with values that did not
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* pass the condition.</span>
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*
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* <img src="./img/partition.png" width="100%">
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*
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* `partition` outputs an array with two Observables that partition the values
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* from the source Observable through the given `predicate` function. The first
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* Observable in that array emits source values for which the predicate argument
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* returns true. The second Observable emits source values for which the
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* predicate returns false. The first behaves like {@link filter} and the second
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* behaves like {@link filter} with the predicate negated.
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*
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* @example <caption>Partition click events into those on DIV elements and those elsewhere</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var parts = clicks.partition(ev => ev.target.tagName === 'DIV');
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* var clicksOnDivs = parts[0];
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* var clicksElsewhere = parts[1];
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* clicksOnDivs.subscribe(x => console.log('DIV clicked: ', x));
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* clicksElsewhere.subscribe(x => console.log('Other clicked: ', x));
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*
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* @see {@link filter}
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*
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* @param {function(value: T, index: number): boolean} predicate A function that
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* evaluates each value emitted by the source Observable. If it returns `true`,
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* the value is emitted on the first Observable in the returned array, if
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* `false` the value is emitted on the second Observable in the array. The
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* `index` parameter is the number `i` for the i-th source emission that has
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* happened since the subscription, starting from the number `0`.
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* @param {any} [thisArg] An optional argument to determine the value of `this`
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* in the `predicate` function.
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* @return {[Observable<T>, Observable<T>]} An array with two Observables: one
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* with values that passed the predicate, and another with values that did not
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* pass the predicate.
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* @method partition
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* @owner Observable
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*/
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export function partition(predicate, thisArg) {
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return (source) => [
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filter(predicate, thisArg)(source),
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filter(not(predicate, thisArg))(source)
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];
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}
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//# sourceMappingURL=partition.js.map
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