forked from sheetjs/sheetjs
68 lines
2.4 KiB
JavaScript
68 lines
2.4 KiB
JavaScript
// https://github.com/davidchambers/Base64.js
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// (C) 2015 David Chambers and contributors
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// Base64.js may be freely distributed under the Apache 2.0 License.
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;(function () {
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var object =
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typeof exports != 'undefined' ? exports :
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typeof self != 'undefined' ? self : // #8: web workers
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$.global; // #31: ExtendScript
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var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
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function InvalidCharacterError(message) {
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this.message = message;
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}
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InvalidCharacterError.prototype = new Error;
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InvalidCharacterError.prototype.name = 'InvalidCharacterError';
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// encoder
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// [https://gist.github.com/999166] by [https://github.com/nignag]
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object.btoa || (
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object.btoa = function (input) {
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var str = String(input);
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for (
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// initialize result and counter
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var block, charCode, idx = 0, map = chars, output = '';
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// if the next str index does not exist:
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// change the mapping table to "="
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// check if d has no fractional digits
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str.charAt(idx | 0) || (map = '=', idx % 1);
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// "8 - idx % 1 * 8" generates the sequence 2, 4, 6, 8
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output += map.charAt(63 & block >> 8 - idx % 1 * 8)
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) {
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charCode = str.charCodeAt(idx += 3/4);
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if (charCode > 0xFF) {
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throw new InvalidCharacterError("'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.");
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}
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block = block << 8 | charCode;
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}
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return output;
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});
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// decoder
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// [https://gist.github.com/1020396] by [https://github.com/atk]
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object.atob || (
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object.atob = function (input) {
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var str = String(input).replace(/[=]+$/, ''); // #31: ExtendScript bad parse of /=
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if (str.length % 4 == 1) {
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throw new InvalidCharacterError("'atob' failed: The string to be decoded is not correctly encoded.");
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}
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for (
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// initialize result and counters
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var bc = 0, bs, buffer, idx = 0, output = '';
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// get next character
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buffer = str.charAt(idx++);
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// character found in table? initialize bit storage and add its ascii value;
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~buffer && (bs = bc % 4 ? bs * 64 + buffer : buffer,
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// and if not first of each 4 characters,
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// convert the first 8 bits to one ascii character
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bc++ % 4) ? output += String.fromCharCode(255 & bs >> (-2 * bc & 6)) : 0
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) {
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// try to find character in table (0-63, not found => -1)
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buffer = chars.indexOf(buffer);
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}
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return output;
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});
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}());
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