// Copyright 2018-2025 the Deno authors. MIT license.
/**
* Creates an iterator that cycles indefinitely over the provided iterable.
*
* Each time the iterable is exhausted, a new iterator is obtained to start the cycle again.
* This generator will yield the values from the iterable continuously.
*
* > **Note:** If the iterable is empty, the generator will keep restarting and yield nothing.
*
* @typeParam T The type of the elements in the iterable.
* @param iterable The iterable whose values are to be cycled.
* @returns A generator that yields values from the iterable in an endless cycle.
*
* @example Basic usage
* ```ts
* import { cycle } from "@std/collections/unstable-cycle";
* import { assertEquals } from "@std/assert";
*
* const cyclic = cycle([1, 2, 3]);
* const result: number[] = [];
*
* for (const num of cyclic) {
* result.push(num);
* if (result.length === 7) break;
* }
*
* assertEquals(result, [1, 2, 3, 1, 2, 3, 1]);
* ```
*/
export function* cycle<T>(iterable: Iterable<T>): Generator<T> {
let iterator = iterable[Symbol.iterator]();
while (true) {
const result = iterator.next();
if (result.done) {
iterator = iterable[Symbol.iterator]();
} else {
yield result.value;
}
}
}
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