Convert hexadecimal string into decimal array in typescript

hex-to-dec.ts

// requires the types from: https://gist.github.com/davidmurdoch/3145903f3a267543568225c68dcc325b

// this is *very* limited in string size at the moment
type Data<T extends string> = {
    value: DATA<T>,
    // @ts-ignore: Ignore type instantiation depth errors as we have already limited our depth
    toBuffer: () => ToUInt8<Hex<Trim<T, "0x">>>
}

type HexLookUp = {"00": 0, "01": 1, "02": 2, "03": 3, "04": 4, "05": 5, "06": 6, "07": 7, "08": 8, "09": 9, "0a": 10, "0b": 11, "0c": 12, "0d": 13, "0e": 14, "0f": 15, "10": 16, "11": 17, "12": 18, "13": 19, "14": 20, "15": 21, "16": 22, "17": 23, "18": 24, "19": 25, "1a": 26, "1b": 27, "1c": 28, "1d": 29, "1e": 30, "1f": 31, "20": 32, "21": 33, "22": 34, "23": 35, "24": 36, "25": 37, "26": 38, "27": 39, "28": 40, "29": 41, "2a": 42, "2b": 43, "2c": 44, "2d": 45, "2e": 46, "2f": 47, "30": 48, "31": 49, "32": 50, "33": 51, "34": 52, "35": 53, "36": 54, "37": 55, "38": 56, "39": 57, "3a": 58, "3b": 59, "3c": 60, "3d": 61, "3e": 62, "3f": 63, "40": 64, "41": 65, "42": 66, "43": 67, "44": 68, "45": 69, "46": 70, "47": 71, "48": 72, "49": 73, "4a": 74, "4b": 75, "4c": 76, "4d": 77, "4e": 78, "4f": 79, "50": 80, "51": 81, "52": 82, "53": 83, "54": 84, "55": 85, "56": 86, "57": 87, "58": 88, "59": 89, "5a": 90, "5b": 91, "5c": 92, "5d": 93, "5e": 94, "5f": 95, "60": 96, "61": 97, "62": 98, "63": 99, "64": 100, "65": 101, "66": 102, "67": 103, "68": 104, "69": 105, "6a": 106, "6b": 107, "6c": 108, "6d": 109, "6e": 110, "6f": 111, "70": 112, "71": 113, "72": 114, "73": 115, "74": 116, "75": 117, "76": 118, "77": 119, "78": 120, "79": 121, "7a": 122, "7b": 123, "7c": 124, "7d": 125, "7e": 126, "7f": 127, "80": 128, "81": 129, "82": 130, "83": 131, "84": 132, "85": 133, "86": 134, "87": 135, "88": 136, "89": 137, "8a": 138, "8b": 139, "8c": 140, "8d": 141, "8e": 142, "8f": 143, "90": 144, "91": 145, "92": 146, "93": 147, "94": 148, "95": 149, "96": 150, "97": 151, "98": 152, "99": 153, "9a": 154, "9b": 155, "9c": 156, "9d": 157, "9e": 158, "9f": 159, "a0": 160, "a1": 161, "a2": 162, "a3": 163, "a4": 164, "a5": 165, "a6": 166, "a7": 167, "a8": 168, "a9": 169, "aa": 170, "ab": 171, "ac": 172, "ad": 173, "ae": 174, "af": 175, "b0": 176, "b1": 177, "b2": 178, "b3": 179, "b4": 180, "b5": 181, "b6": 182, "b7": 183, "b8": 184, "b9": 185, "ba": 186, "bb": 187, "bc": 188, "bd": 189, "be": 190, "bf": 191, "c0": 192, "c1": 193, "c2": 194, "c3": 195, "c4": 196, "c5": 197, "c6": 198, "c7": 199, "c8": 200, "c9": 201, "ca": 202, "cb": 203, "cc": 204, "cd": 205, "ce": 206, "cf": 207, "d0": 208, "d1": 209, "d2": 210, "d3": 211, "d4": 212, "d5": 213, "d6": 214, "d7": 215, "d8": 216, "d9": 217, "da": 218, "db": 219, "dc": 220, "dd": 221, "de": 222, "df": 223, "e0": 224, "e1": 225, "e2": 226, "e3": 227, "e4": 228, "e5": 229, "e6": 230, "e7": 231, "e8": 232, "e9": 233, "ea": 234, "eb": 235, "ec": 236, "ed": 237, "ee": 238, "ef": 239, "f0": 240, "f1": 241, "f2": 242, "f3": 243, "f4": 244, "f5": 245, "f6": 246, "f7": 247, "f8": 248, "f9": 249, "fa": 250, "fb": 251, "fc": 252, "fd": 253, "fe": 254, "ff": 255}
type ReverseHexLookUp = {[K in keyof HexLookUp as HexLookUp[K]]: K};

type ToUInt8<H extends HexPairs[]> = H extends [infer I, ...infer Rest]
  ? I extends keyof HexLookUp
    ? [HexLookUp[I], ...ToUInt8<Cast<Rest, HexPairs[]>>]
    : never
  : [];


declare const d: Data<"0xff6b938acb7d72010530aa">;
const buf = d.toBuffer();

This requires the types from: https://gist.github.com/davidmurdoch/3145903f3a267543568225c68dcc325b

Fun fact, you can already write ReverseHexLookUp in TypeScript 4.0:

type ReverseHexLookUp = {
	[K in keyof HexLookUp extends infer T
		? T extends keyof HexLookUp
			? HexLookUp[T]
			: never
		: never
	]: keyof HexLookUp extends infer U
		? U extends keyof HexLookUp
			? HexLookUp[U] extends K
				? U
				: never
			: never
		: never;
};

Based on: type-challenges/type-challenges#141