1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
import { assert } from "../assert/assert.ts";
export function runLengthEncode(arr: number[]) {  const data: number[] = [];  const runLengths: number[] = [];
  let prev: symbol | number = Symbol("none");
  for (const x of arr) {    if (x === prev) {      ++runLengths[runLengths.length - 1];    } else {      prev = x;      data.push(x);      runLengths.push(1);    }  }
  assert(runLengths.every((r) => r < 0x100));
  return {    d: btoa(String.fromCharCode(...data)),    r: btoa(String.fromCharCode(...runLengths)),  };}
export function runLengthDecode({ d, r }: { d: string; r: string }) {  const data = atob(d);  const runLengths = atob(r);  let out = "";
  for (const [i, ch] of [...runLengths].entries()) {    out += data[i]!.repeat(ch.codePointAt(0)!);  }
  return Uint8Array.from([...out].map((x) => x.codePointAt(0)!));}