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unzip.ts
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unzip.ts
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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
/**
* Builds two separate arrays from the given array of 2-tuples, with the first
* returned array holding all first tuple elements and the second one holding
* all the second elements.
*
* ```ts
* import { unzip } from "https://deno.land/std@$STD_VERSION/collections/unzip.ts";
* import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts";
*
* const parents = [
* ["Maria", "Jeff"],
* ["Anna", "Kim"],
* ["John", "Leroy"],
* ] as [string, string][];
*
* const [moms, dads] = unzip(parents);
*
* assertEquals(moms, ["Maria", "Anna", "John"]);
* assertEquals(dads, ["Jeff", "Kim", "Leroy"]);
* ```
*/
export function unzip<T, U>(pairs: readonly [T, U][]): [T[], U[]] {
const { length } = pairs;
const ret: [T[], U[]] = [
Array<T>(length),
Array<U>(length),
];
pairs.forEach(([first, second], index) => {
ret[0][index] = first;
ret[1][index] = second;
});
return ret;
}