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