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repeat.ts
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repeat.ts
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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.
import { copy } from "./copy.ts";
/** Returns a new Uint8Array composed of `count` repetitions of the `source`
* array.
*
* If `count` is negative, a `RangeError` is thrown.
*
* ```ts
* import { repeat } from "https://deno.land/std@$STD_VERSION/bytes/repeat.ts";
* const source = new Uint8Array([0, 1, 2]);
* console.log(repeat(source, 3)); // [0, 1, 2, 0, 1, 2, 0, 1, 2]
* console.log(repeat(source, 0)); // []
* console.log(repeat(source, -1)); // RangeError
* ```
*/
export function repeat(source: Uint8Array, count: number): Uint8Array {
if (count === 0) {
return new Uint8Array();
}
if (count < 0) {
throw new RangeError("bytes: negative repeat count");
}
if (!Number.isInteger(count)) {
throw new Error("bytes: repeat count must be an integer");
}
const nb = new Uint8Array(source.length * count);
let bp = copy(source, nb);
for (; bp < nb.length; bp *= 2) {
copy(nb.slice(0, bp), nb, bp);
}
return nb;
}