/
intersect.ts
33 lines (29 loc) · 1.02 KB
/
intersect.ts
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
import { filterInPlace } from "./_utils.ts";
/**
* Returns all distinct elements that appear at least once in each of the given arrays
*
* Example:
*
* ```ts
* import { intersect } from "https://deno.land/std@$STD_VERSION/collections/mod.ts";
* import { assertEquals } from "https://deno.land/std@$STD_VERSION/testing/asserts.ts";
*
* const lisaInterests = [ 'Cooking', 'Music', 'Hiking' ]
* const kimInterests = [ 'Music', 'Tennis', 'Cooking' ]
* const commonInterests = intersect(lisaInterests, kimInterests)
*
* assertEquals(commonInterests, [ 'Cooking', 'Music' ])
* ```
*/
export function intersect<T>(...arrays: (readonly T[])[]): T[] {
const [originalHead, ...tail] = arrays;
const head = [...new Set(originalHead)];
const tailSets = tail.map((it) => new Set(it));
for (const set of tailSets) {
filterInPlace(head, (it) => set.has(it));
if (head.length === 0) return head;
}
return head;
}