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JavaScript

/*! https://mths.be/utf8js v2.1.2 by @mathias */
var stringFromCharCode = String.fromCharCode;
// Taken from https://mths.be/punycode
function ucs2decode(string) {
var output = [];
var counter = 0;
var length = string.length;
var value;
var extra;
while (counter < length) {
value = string.charCodeAt(counter++);
if (value >= 0xD800 && value <= 0xDBFF && counter < length) {
// high surrogate, and there is a next character
extra = string.charCodeAt(counter++);
if ((extra & 0xFC00) == 0xDC00) { // low surrogate
output.push(((value & 0x3FF) << 10) + (extra & 0x3FF) + 0x10000);
} else {
// unmatched surrogate; only append this code unit, in case the next
// code unit is the high surrogate of a surrogate pair
output.push(value);
counter--;
}
} else {
output.push(value);
}
}
return output;
}
// Taken from https://mths.be/punycode
function ucs2encode(array) {
var length = array.length;
var index = -1;
var value;
var output = '';
while (++index < length) {
value = array[index];
if (value > 0xFFFF) {
value -= 0x10000;
output += stringFromCharCode(value >>> 10 & 0x3FF | 0xD800);
value = 0xDC00 | value & 0x3FF;
}
output += stringFromCharCode(value);
}
return output;
}
function checkScalarValue(codePoint, strict) {
if (codePoint >= 0xD800 && codePoint <= 0xDFFF) {
if (strict) {
throw Error(
'Lone surrogate U+' + codePoint.toString(16).toUpperCase() +
' is not a scalar value'
);
}
return false;
}
return true;
}
/*--------------------------------------------------------------------------*/
function createByte(codePoint, shift) {
return stringFromCharCode(((codePoint >> shift) & 0x3F) | 0x80);
}
function encodeCodePoint(codePoint, strict) {
if ((codePoint & 0xFFFFFF80) == 0) { // 1-byte sequence
return stringFromCharCode(codePoint);
}
var symbol = '';
if ((codePoint & 0xFFFFF800) == 0) { // 2-byte sequence
symbol = stringFromCharCode(((codePoint >> 6) & 0x1F) | 0xC0);
}
else if ((codePoint & 0xFFFF0000) == 0) { // 3-byte sequence
if (!checkScalarValue(codePoint, strict)) {
codePoint = 0xFFFD;
}
symbol = stringFromCharCode(((codePoint >> 12) & 0x0F) | 0xE0);
symbol += createByte(codePoint, 6);
}
else if ((codePoint & 0xFFE00000) == 0) { // 4-byte sequence
symbol = stringFromCharCode(((codePoint >> 18) & 0x07) | 0xF0);
symbol += createByte(codePoint, 12);
symbol += createByte(codePoint, 6);
}
symbol += stringFromCharCode((codePoint & 0x3F) | 0x80);
return symbol;
}
function utf8encode(string, opts) {
opts = opts || {};
var strict = false !== opts.strict;
var codePoints = ucs2decode(string);
var length = codePoints.length;
var index = -1;
var codePoint;
var byteString = '';
while (++index < length) {
codePoint = codePoints[index];
byteString += encodeCodePoint(codePoint, strict);
}
return byteString;
}
/*--------------------------------------------------------------------------*/
function readContinuationByte() {
if (byteIndex >= byteCount) {
throw Error('Invalid byte index');
}
var continuationByte = byteArray[byteIndex] & 0xFF;
byteIndex++;
if ((continuationByte & 0xC0) == 0x80) {
return continuationByte & 0x3F;
}
// If we end up here, its not a continuation byte
throw Error('Invalid continuation byte');
}
function decodeSymbol(strict) {
var byte1;
var byte2;
var byte3;
var byte4;
var codePoint;
if (byteIndex > byteCount) {
throw Error('Invalid byte index');
}
if (byteIndex == byteCount) {
return false;
}
// Read first byte
byte1 = byteArray[byteIndex] & 0xFF;
byteIndex++;
// 1-byte sequence (no continuation bytes)
if ((byte1 & 0x80) == 0) {
return byte1;
}
// 2-byte sequence
if ((byte1 & 0xE0) == 0xC0) {
byte2 = readContinuationByte();
codePoint = ((byte1 & 0x1F) << 6) | byte2;
if (codePoint >= 0x80) {
return codePoint;
} else {
throw Error('Invalid continuation byte');
}
}
// 3-byte sequence (may include unpaired surrogates)
if ((byte1 & 0xF0) == 0xE0) {
byte2 = readContinuationByte();
byte3 = readContinuationByte();
codePoint = ((byte1 & 0x0F) << 12) | (byte2 << 6) | byte3;
if (codePoint >= 0x0800) {
return checkScalarValue(codePoint, strict) ? codePoint : 0xFFFD;
} else {
throw Error('Invalid continuation byte');
}
}
// 4-byte sequence
if ((byte1 & 0xF8) == 0xF0) {
byte2 = readContinuationByte();
byte3 = readContinuationByte();
byte4 = readContinuationByte();
codePoint = ((byte1 & 0x07) << 0x12) | (byte2 << 0x0C) |
(byte3 << 0x06) | byte4;
if (codePoint >= 0x010000 && codePoint <= 0x10FFFF) {
return codePoint;
}
}
throw Error('Invalid UTF-8 detected');
}
var byteArray;
var byteCount;
var byteIndex;
function utf8decode(byteString, opts) {
opts = opts || {};
var strict = false !== opts.strict;
byteArray = ucs2decode(byteString);
byteCount = byteArray.length;
byteIndex = 0;
var codePoints = [];
var tmp;
while ((tmp = decodeSymbol(strict)) !== false) {
codePoints.push(tmp);
}
return ucs2encode(codePoints);
}
module.exports = {
version: '2.1.2',
encode: utf8encode,
decode: utf8decode
};