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// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
// Forked from https://github.com/beatgammit/base64-js
// Copyright (c) 2014 Jameson Little. MIT License.
const lookup: string[] = [];
const revLookup: number[] = [];
const code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (let i = 0, len = code.length; i < len; ++i) {
lookup[i] = code[i];
revLookup[code.charCodeAt(i)] = i;
}
// Support decoding URL-safe base64 strings, as Node.js does.
// See: https://en.wikipedia.org/wiki/Base64#URL_applications
revLookup["-".charCodeAt(0)] = 62;
revLookup["_".charCodeAt(0)] = 63;
function getLens(b64: string): [number, number] {
const len = b64.length;
if (len % 4 > 0) {
throw new Error("Invalid string. Length must be a multiple of 4");
}
// Trim off extra bytes after placeholder bytes are found
// See: https://github.com/beatgammit/base64-js/issues/42
let validLen = b64.indexOf("=");
if (validLen === -1) validLen = len;
const placeHoldersLen = validLen === len ? 0 : 4 - (validLen % 4);
return [validLen, placeHoldersLen];
}
// base64 is 4/3 + up to two characters of the original data
export function byteLength(b64: string): number {
const lens = getLens(b64);
const validLen = lens[0];
const placeHoldersLen = lens[1];
return ((validLen + placeHoldersLen) * 3) / 4 - placeHoldersLen;
}
function _byteLength(
b64: string,
validLen: number,
placeHoldersLen: number
): number {
return ((validLen + placeHoldersLen) * 3) / 4 - placeHoldersLen;
}
export function toByteArray(b64: string): Uint8Array {
let tmp;
const lens = getLens(b64);
const validLen = lens[0];
const placeHoldersLen = lens[1];
const arr = new Uint8Array(_byteLength(b64, validLen, placeHoldersLen));
let curByte = 0;
// if there are placeholders, only get up to the last complete 4 chars
const len = placeHoldersLen > 0 ? validLen - 4 : validLen;
let i;
for (i = 0; i < len; i += 4) {
tmp =
(revLookup[b64.charCodeAt(i)] << 18) |
(revLookup[b64.charCodeAt(i + 1)] << 12) |
(revLookup[b64.charCodeAt(i + 2)] << 6) |
revLookup[b64.charCodeAt(i + 3)];
arr[curByte++] = (tmp >> 16) & 0xff;
arr[curByte++] = (tmp >> 8) & 0xff;
arr[curByte++] = tmp & 0xff;
}
if (placeHoldersLen === 2) {
tmp =
(revLookup[b64.charCodeAt(i)] << 2) |
(revLookup[b64.charCodeAt(i + 1)] >> 4);
arr[curByte++] = tmp & 0xff;
}
if (placeHoldersLen === 1) {
tmp =
(revLookup[b64.charCodeAt(i)] << 10) |
(revLookup[b64.charCodeAt(i + 1)] << 4) |
(revLookup[b64.charCodeAt(i + 2)] >> 2);
arr[curByte++] = (tmp >> 8) & 0xff;
arr[curByte++] = tmp & 0xff;
}
return arr;
}
function tripletToBase64(num: number): string {
return (
lookup[(num >> 18) & 0x3f] +
lookup[(num >> 12) & 0x3f] +
lookup[(num >> 6) & 0x3f] +
lookup[num & 0x3f]
);
}
function encodeChunk(uint8: Uint8Array, start: number, end: number): string {
let tmp;
const output = [];
for (let i = start; i < end; i += 3) {
tmp =
((uint8[i] << 16) & 0xff0000) +
((uint8[i + 1] << 8) & 0xff00) +
(uint8[i + 2] & 0xff);
output.push(tripletToBase64(tmp));
}
return output.join("");
}
export function fromByteArray(uint8: Uint8Array): string {
let tmp;
const len = uint8.length;
const extraBytes = len % 3; // if we have 1 byte left, pad 2 bytes
const parts = [];
const maxChunkLength = 16383; // must be multiple of 3
// go through the array every three bytes, we'll deal with trailing stuff later
for (let i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
parts.push(
encodeChunk(
uint8,
i,
i + maxChunkLength > len2 ? len2 : i + maxChunkLength
)
);
}
// pad the end with zeros, but make sure to not forget the extra bytes
if (extraBytes === 1) {
tmp = uint8[len - 1];
parts.push(lookup[tmp >> 2] + lookup[(tmp << 4) & 0x3f] + "==");
} else if (extraBytes === 2) {
tmp = (uint8[len - 2] << 8) + uint8[len - 1];
parts.push(
lookup[tmp >> 10] +
lookup[(tmp >> 4) & 0x3f] +
lookup[(tmp << 2) & 0x3f] +
"="
);
}
return parts.join("");
}
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