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partition_entries.ts
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partition_entries.ts
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
/**
* Returns a tuple of two records with the first one containing all entries of
* the given record that match the given predicate and the second one containing
* all that do not.
*
* @example
* ```ts
* import { partitionEntries } from "https://deno.land/std@$STD_VERSION/collections/partition_entries.ts";
* import { assertEquals } from "https://deno.land/std@$STD_VERSION/assert/assert_equals.ts";
*
* const menu = {
* "Salad": 11,
* "Soup": 8,
* "Pasta": 13,
* } as const;
* const myOptions = partitionEntries(
* menu,
* ([item, price]) => item !== "Pasta" && price < 10,
* );
*
* assertEquals(
* myOptions,
* [
* { "Soup": 8 },
* { "Salad": 11, "Pasta": 13 },
* ],
* );
* ```
*/
export function partitionEntries<T>(
record: Readonly<Record<string, T>>,
predicate: (entry: [string, T]) => boolean,
): [match: Record<string, T>, rest: Record<string, T>] {
const match: Record<string, T> = {};
const rest: Record<string, T> = {};
const entries = Object.entries(record);
for (const [key, value] of entries) {
if (predicate([key, value])) {
match[key] = value;
} else {
rest[key] = value;
}
}
return [match, rest];
}