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"use strict";
/**
* A minimal base64 implementation for number arrays.
* @memberof util
* @namespace
*/
var base64 = exports;
/**
* Calculates the byte length of a base64 encoded string.
* @param {string} string Base64 encoded string
* @returns {number} Byte length
*/
base64.length = function length(string) {
var p = string.length;
if (!p)
return 0;
var n = 0;
while (--p % 4 > 1 && string.charAt(p) === "=")
++n;
return Math.ceil(string.length * 3) / 4 - n;
};
// Base64 encoding table
var b64 = new Array(64);
// Base64 decoding table
var s64 = new Array(123);
// 65..90, 97..122, 48..57, 43, 47
for (var i = 0; i < 64;)
s64[b64[i] = i < 26 ? i + 65 : i < 52 ? i + 71 : i < 62 ? i - 4 : i - 59 | 43] = i++;
/**
* Encodes a buffer to a base64 encoded string.
* @param {Uint8Array} buffer Source buffer
* @param {number} start Source start
* @param {number} end Source end
* @returns {string} Base64 encoded string
*/
base64.encode = function encode(buffer, start, end) {
var parts = null,
chunk = [];
var i = 0, // output index
j = 0, // goto index
t; // temporary
while (start < end) {
var b = buffer[start++];
switch (j) {
case 0:
chunk[i++] = b64[b >> 2];
t = (b & 3) << 4;
j = 1;
break;
case 1:
chunk[i++] = b64[t | b >> 4];
t = (b & 15) << 2;
j = 2;
break;
case 2:
chunk[i++] = b64[t | b >> 6];
chunk[i++] = b64[b & 63];
j = 0;
break;
}
if (i > 8191) {
(parts || (parts = [])).push(String.fromCharCode.apply(String, chunk));
i = 0;
}
}
if (j) {
chunk[i++] = b64[t];
chunk[i++] = 61;
if (j === 1)
chunk[i++] = 61;
}
if (parts) {
if (i)
parts.push(String.fromCharCode.apply(String, chunk.slice(0, i)));
return parts.join("");
}
return String.fromCharCode.apply(String, chunk.slice(0, i));
};
var invalidEncoding = "invalid encoding";
/**
* Decodes a base64 encoded string to a buffer.
* @param {string} string Source string
* @param {Uint8Array} buffer Destination buffer
* @param {number} offset Destination offset
* @returns {number} Number of bytes written
* @throws {Error} If encoding is invalid
*/
base64.decode = function decode(string, buffer, offset) {
var start = offset;
var j = 0, // goto index
t; // temporary
for (var i = 0; i < string.length;) {
var c = string.charCodeAt(i++);
if (c === 61 && j > 1)
break;
if ((c = s64[c]) === undefined)
throw Error(invalidEncoding);
switch (j) {
case 0:
t = c;
j = 1;
break;
case 1:
buffer[offset++] = t << 2 | (c & 48) >> 4;
t = c;
j = 2;
break;
case 2:
buffer[offset++] = (t & 15) << 4 | (c & 60) >> 2;
t = c;
j = 3;
break;
case 3:
buffer[offset++] = (t & 3) << 6 | c;
j = 0;
break;
}
}
if (j === 1)
throw Error(invalidEncoding);
return offset - start;
};
/**
* Tests if the specified string appears to be base64 encoded.
* @param {string} string String to test
* @returns {boolean} `true` if probably base64 encoded, otherwise false
*/
base64.test = function test(string) {
return /^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$/.test(string);
};
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