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// Ported from Go
// https://github.com/golang/go/blob/go1.12.5/src/encoding/hex/hex.go
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
const hextable = new TextEncoder().encode("0123456789abcdef");
export function errInvalidByte(byte: number): Error {
return new Error(
"encoding/hex: invalid byte: " +
new TextDecoder().decode(new Uint8Array([byte])),
);
}
export function errLength(): Error {
return new Error("encoding/hex: odd length hex string");
}
// fromHexChar converts a hex character into its value.
function fromHexChar(byte: number): number {
// '0' <= byte && byte <= '9'
if (48 <= byte && byte <= 57) return byte - 48;
// 'a' <= byte && byte <= 'f'
if (97 <= byte && byte <= 102) return byte - 97 + 10;
// 'A' <= byte && byte <= 'F'
if (65 <= byte && byte <= 70) return byte - 65 + 10;
throw errInvalidByte(byte);
}
/**
* EncodedLen returns the length of an encoding of n source bytes. Specifically,
* it returns n * 2.
* @param n
*/
export function encodedLen(n: number): number {
return n * 2;
}
/**
* Encode encodes `src` into `encodedLen(src.length)` bytes.
* @param src
*/
export function encode(src: Uint8Array): Uint8Array {
const dst = new Uint8Array(encodedLen(src.length));
for (let i = 0; i < dst.length; i++) {
const v = src[i];
dst[i * 2] = hextable[v >> 4];
dst[i * 2 + 1] = hextable[v & 0x0f];
}
return dst;
}
/**
* EncodeToString returns the hexadecimal encoding of `src`.
* @param src
*/
export function encodeToString(src: Uint8Array): string {
return new TextDecoder().decode(encode(src));
}
/**
* Decode decodes `src` into `decodedLen(src.length)` bytes
* If the input is malformed an error will be thrown
* the error.
* @param src
*/
export function decode(src: Uint8Array): Uint8Array {
const dst = new Uint8Array(decodedLen(src.length));
for (let i = 0; i < dst.length; i++) {
const a = fromHexChar(src[i * 2]);
const b = fromHexChar(src[i * 2 + 1]);
dst[i] = (a << 4) | b;
}
if (src.length % 2 == 1) {
// Check for invalid char before reporting bad length,
// since the invalid char (if present) is an earlier problem.
fromHexChar(src[dst.length * 2]);
throw errLength();
}
return dst;
}
/**
* DecodedLen returns the length of decoding `x` source bytes.
* Specifically, it returns `x / 2`.
* @param x
*/
export function decodedLen(x: number): number {
return x >>> 1;
}
/**
* DecodeString returns the bytes represented by the hexadecimal string `s`.
* DecodeString expects that src contains only hexadecimal characters and that
* src has even length.
* If the input is malformed, DecodeString will throw an error.
* @param s the `string` to decode to `Uint8Array`
*/
export function decodeString(s: string): Uint8Array {
return decode(new TextEncoder().encode(s));
}
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