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