118 lines
3.7 KiB
JavaScript
118 lines
3.7 KiB
JavaScript
'use strict';
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exports.byteLength = byteLength;
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exports.toByteArray = toByteArray;
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exports.fromByteArray = fromByteArray;
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var lookup = [];
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var revLookup = [];
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var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array;
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var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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for (var i = 0, len = code.length; i < len; ++i) {
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lookup[i] = code[i];
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revLookup[code.charCodeAt(i)] = i;
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} // Support decoding URL-safe base64 strings, as Node.js does.
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// See: https://en.wikipedia.org/wiki/Base64#URL_applications
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revLookup['-'.charCodeAt(0)] = 62;
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revLookup['_'.charCodeAt(0)] = 63;
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function getLens(b64) {
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var len = b64.length;
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if (len % 4 > 0) {
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throw new Error('Invalid string. Length must be a multiple of 4');
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} // Trim off extra bytes after placeholder bytes are found
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// See: https://github.com/beatgammit/base64-js/issues/42
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var validLen = b64.indexOf('=');
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if (validLen === -1) validLen = len;
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var placeHoldersLen = validLen === len ? 0 : 4 - validLen % 4;
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return [validLen, placeHoldersLen];
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} // base64 is 4/3 + up to two characters of the original data
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function byteLength(b64) {
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var lens = getLens(b64);
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var validLen = lens[0];
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var placeHoldersLen = lens[1];
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return (validLen + placeHoldersLen) * 3 / 4 - placeHoldersLen;
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}
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function _byteLength(b64, validLen, placeHoldersLen) {
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return (validLen + placeHoldersLen) * 3 / 4 - placeHoldersLen;
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}
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function toByteArray(b64) {
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var tmp;
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var lens = getLens(b64);
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var validLen = lens[0];
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var placeHoldersLen = lens[1];
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var arr = new Arr(_byteLength(b64, validLen, placeHoldersLen));
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var curByte = 0; // if there are placeholders, only get up to the last complete 4 chars
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var len = placeHoldersLen > 0 ? validLen - 4 : validLen;
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for (var i = 0; i < len; i += 4) {
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tmp = revLookup[b64.charCodeAt(i)] << 18 | revLookup[b64.charCodeAt(i + 1)] << 12 | revLookup[b64.charCodeAt(i + 2)] << 6 | revLookup[b64.charCodeAt(i + 3)];
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arr[curByte++] = tmp >> 16 & 0xFF;
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arr[curByte++] = tmp >> 8 & 0xFF;
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arr[curByte++] = tmp & 0xFF;
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}
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if (placeHoldersLen === 2) {
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tmp = revLookup[b64.charCodeAt(i)] << 2 | revLookup[b64.charCodeAt(i + 1)] >> 4;
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arr[curByte++] = tmp & 0xFF;
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}
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if (placeHoldersLen === 1) {
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tmp = revLookup[b64.charCodeAt(i)] << 10 | revLookup[b64.charCodeAt(i + 1)] << 4 | revLookup[b64.charCodeAt(i + 2)] >> 2;
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arr[curByte++] = tmp >> 8 & 0xFF;
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arr[curByte++] = tmp & 0xFF;
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}
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return arr;
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}
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function tripletToBase64(num) {
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return lookup[num >> 18 & 0x3F] + lookup[num >> 12 & 0x3F] + lookup[num >> 6 & 0x3F] + lookup[num & 0x3F];
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}
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function encodeChunk(uint8, start, end) {
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var tmp;
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var output = [];
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for (var i = start; i < end; i += 3) {
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tmp = (uint8[i] << 16 & 0xFF0000) + (uint8[i + 1] << 8 & 0xFF00) + (uint8[i + 2] & 0xFF);
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output.push(tripletToBase64(tmp));
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}
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return output.join('');
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}
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function fromByteArray(uint8) {
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var tmp;
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var len = uint8.length;
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var extraBytes = len % 3; // if we have 1 byte left, pad 2 bytes
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var parts = [];
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var maxChunkLength = 16383; // must be multiple of 3
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// go through the array every three bytes, we'll deal with trailing stuff later
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for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
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parts.push(encodeChunk(uint8, i, i + maxChunkLength > len2 ? len2 : i + maxChunkLength));
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} // pad the end with zeros, but make sure to not forget the extra bytes
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if (extraBytes === 1) {
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tmp = uint8[len - 1];
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parts.push(lookup[tmp >> 2] + lookup[tmp << 4 & 0x3F] + '==');
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} else if (extraBytes === 2) {
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tmp = (uint8[len - 2] << 8) + uint8[len - 1];
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parts.push(lookup[tmp >> 10] + lookup[tmp >> 4 & 0x3F] + lookup[tmp << 2 & 0x3F] + '=');
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}
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return parts.join('');
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} |