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std/collections/intersect.ts

Deno standard library
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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;}