Add fallback base64 codec for crippled browsers
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/*
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* Copyright (c) 2010 Nick Galbreath
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* http://code.google.com/p/stringencoders/source/browse/#svn/trunk/javascript
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following
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* conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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/* base64 encode/decode compatible with window.btoa/atob
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*
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* window.atob/btoa is a Firefox extension to convert binary data (the "b")
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* to base64 (ascii, the "a").
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*
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* It is also found in Safari and Chrome. It is not available in IE.
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*
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* if (!window.btoa) window.btoa = base64.encode
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* if (!window.atob) window.atob = base64.decode
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*
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* The original spec's for atob/btoa are a bit lacking
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* https://developer.mozilla.org/en/DOM/window.atob
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* https://developer.mozilla.org/en/DOM/window.btoa
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*
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* window.btoa and base64.encode takes a string where charCodeAt is [0,255]
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* If any character is not [0,255], then an DOMException(5) is thrown.
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*
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* window.atob and base64.decode take a base64-encoded string
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* If the input length is not a multiple of 4, or contains invalid characters
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* then an DOMException(5) is thrown.
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*/
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var base64 = {};
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base64.PADCHAR = '=';
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base64.ALPHA = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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base64.makeDOMException = function() {
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// sadly in FF,Safari,Chrome you can't make a DOMException
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var e, tmp;
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try {
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return new DOMException(DOMException.INVALID_CHARACTER_ERR);
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} catch (tmp) {
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// not available, just passback a duck-typed equiv
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// https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Error
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// https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Error/prototype
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var ex = new Error("DOM Exception 5");
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// ex.number and ex.description is IE-specific.
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ex.code = ex.number = 5;
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ex.name = ex.description = "INVALID_CHARACTER_ERR";
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// Safari/Chrome output format
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ex.toString = function() { return 'Error: ' + ex.name + ': ' + ex.message; };
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return ex;
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}
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}
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base64.getbyte64 = function(s,i) {
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// This is oddly fast, except on Chrome/V8.
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// Minimal or no improvement in performance by using a
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// object with properties mapping chars to value (eg. 'A': 0)
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var idx = base64.ALPHA.indexOf(s.charAt(i));
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if (idx === -1) {
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throw base64.makeDOMException();
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}
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return idx;
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}
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base64.decode = function(s) {
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// convert to string
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s = '' + s;
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var getbyte64 = base64.getbyte64;
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var pads, i, b10;
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var imax = s.length
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if (imax === 0) {
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return s;
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}
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if (imax % 4 !== 0) {
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throw base64.makeDOMException();
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}
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pads = 0
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if (s.charAt(imax - 1) === base64.PADCHAR) {
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pads = 1;
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if (s.charAt(imax - 2) === base64.PADCHAR) {
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pads = 2;
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}
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// either way, we want to ignore this last block
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imax -= 4;
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}
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var x = [];
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for (i = 0; i < imax; i += 4) {
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b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12) |
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(getbyte64(s,i+2) << 6) | getbyte64(s,i+3);
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x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 0xff, b10 & 0xff));
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}
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switch (pads) {
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case 1:
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b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12) | (getbyte64(s,i+2) << 6);
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x.push(String.fromCharCode(b10 >> 16, (b10 >> 8) & 0xff));
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break;
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case 2:
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b10 = (getbyte64(s,i) << 18) | (getbyte64(s,i+1) << 12);
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x.push(String.fromCharCode(b10 >> 16));
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break;
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}
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return x.join('');
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}
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base64.getbyte = function(s,i) {
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var x = s.charCodeAt(i);
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if (x > 255) {
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throw base64.makeDOMException();
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}
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return x;
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}
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base64.encode = function(s) {
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if (arguments.length !== 1) {
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throw new SyntaxError("Not enough arguments");
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}
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var padchar = base64.PADCHAR;
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var alpha = base64.ALPHA;
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var getbyte = base64.getbyte;
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var i, b10;
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var x = [];
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// convert to string
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s = '' + s;
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var imax = s.length - s.length % 3;
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if (s.length === 0) {
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return s;
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}
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for (i = 0; i < imax; i += 3) {
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b10 = (getbyte(s,i) << 16) | (getbyte(s,i+1) << 8) | getbyte(s,i+2);
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x.push(alpha.charAt(b10 >> 18));
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x.push(alpha.charAt((b10 >> 12) & 0x3F));
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x.push(alpha.charAt((b10 >> 6) & 0x3f));
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x.push(alpha.charAt(b10 & 0x3f));
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}
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switch (s.length - imax) {
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case 1:
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b10 = getbyte(s,i) << 16;
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x.push(alpha.charAt(b10 >> 18) + alpha.charAt((b10 >> 12) & 0x3F) +
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padchar + padchar);
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break;
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case 2:
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b10 = (getbyte(s,i) << 16) | (getbyte(s,i+1) << 8);
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x.push(alpha.charAt(b10 >> 18) + alpha.charAt((b10 >> 12) & 0x3F) +
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alpha.charAt((b10 >> 6) & 0x3f) + padchar);
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break;
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}
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return x.join('');
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}
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if (!window.btoa) window.btoa = base64.encode;
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if (!window.atob) window.atob = base64.decode;
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