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