repo_description: Node.js JavaScript runtime ✨🐢🚀✨
repo_topics: javascript js linux macos mit node nodejs runtime windows
code: 'use strict';
  const {
    isInsideNodeModules,
  } = internalBinding('util');
  
  if (!isInsideNodeModules()) {
  	process.emitWarning(
  		'The `punycode` module is deprecated. Please use a userland ' +
  		'alternative instead.',
  		'DeprecationWarning',
  		'DEP0040',
  	);
  }
  
  /** Highest positive signed 32-bit float value */
  const maxInt = 2147483647; // aka. 0x7FFFFFFF or 2^31-1
  
  /** Bootstring parameters */
  const base = 36;
  const tMin = 1;
  const tMax = 26;
  const skew = 38;
  const damp = 700;
  const initialBias = 72;
  const initialN = 128; // 0x80
  const delimiter = '-'; // '\x2D'
  
  /** Regular expressions */
  const regexPunycode = /^xn--/;
  const regexNonASCII = /[^\0-\x7F]/; // Note: U+007F DEL is excluded too.
  const regexSeparators = /[\x2E\u3002\uFF0E\uFF61]/g; // RFC 3490 separators
  
  /** Error messages */
  const errors = {
  	'overflow': 'Overflow: input needs wider integers to process',
  	'not-basic': 'Illegal input >= 0x80 (not a basic code point)',
  	'invalid-input': 'Invalid input'
  };
  
  /** Convenience shortcuts */
  const baseMinusTMin = base - tMin;
  const floor = Math.floor;
  const stringFromCharCode = String.fromCharCode;
  
  /*--------------------------------------------------------------------------*/
  
  /**
   * A generic error utility function.
   * @private
   * @param {String} type The error type.
   * @returns {Error} Throws a `RangeError` with the applicable error message.
   */
  function error(type) {
  	throw new RangeError(errors[type]);
  }
  
  /**
   * A generic `Array#map` utility function.
   * @private
   * @param {Array} array The array to iterate over.
   * @param {Function} callback The function that gets called for every array
   * item.
   * @returns {Array} A new array of values returned by the callback function.
   */
  function map(array, callback) {
  	const result = [];
  	let length = array.length;
  	while (length--) {
  		result[length] = callback(array[length]);
  	}
  	return result;
  }
  
  /**
   * A simple `Array#map`-like wrapper to work with domain name strings or email
   * addresses.
   * @private
   * @param {String} domain The domain name or email address.
   * @param {Function} callback The function that gets called for every
   * character.
   * @returns {String} A new string of characters returned by the callback
   * function.
   */
  function mapDomain(domain, callback) {
  	const parts = domain.split('@');
  	let result = '';
  	if (parts.length > 1) {
  		// In email addresses, only the domain name should be punycoded. Leave
  		// the local part (i.e. everything up to `@`) intact.
  		result = parts[0] + '@';
  		domain = parts[1];
  	}
  	// Avoid `split(regex)` for IE8 compatibility. See #17.
  	domain = domain.replace(regexSeparators, '\x2E');
  	const labels = domain.split('.');
  	const encoded = map(labels, callback).join('.');
  	return result + encoded;
  }
  
  /**
   * Creates an array containing the numeric code points of each Unicode
   * character in the string. While JavaScript uses UCS-2 internally,
   * this function will convert a pair of surrogate halves (each of which
   * UCS-2 exposes as separate characters) into a single code point,
   * matching UTF-16.
   * @see `punycode.ucs2.encode`
   * @see <https://mathiasbynens.be/notes/javascript-encoding>
   * @memberOf punycode.ucs2
   * @name decode
   * @param {String} string The Unicode input string (UCS-2).
   * @returns {Array} The new array of code points.
   */
  function ucs2decode(string) {
  	const output = [];
  	let counter = 0;
  	const length = string.length;
  	while (counter < length) {
  		const value = string.charCodeAt(counter++);
  		if (value >= 0xD800 && value <= 0xDBFF && counter < length) {
  			// It's a high surrogate, and there is a next character.
  			const extra = string.charCodeAt(counter++);
  			if ((extra & 0xFC00) == 0xDC00) { // Low surrogate.
  				output.push(((value & 0x3FF) << 10) + (extra & 0x3FF) + 0x10000);
  			} else {
  				// It's an 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;
  }
  
  /**
   * Creates a string based on an array of numeric code points.
   * @see `punycode.ucs2.decode`
   * @memberOf punycode.ucs2
   * @name encode
   * @param {Array} codePoints The array of numeric code points.
   * @returns {String} The new Unicode string (UCS-2).
   */
  const ucs2encode = codePoints => String.fromCodePoint(...codePoints);
  
  /**
   * Converts a basic code point into a digit/integer.
   * @see `digitToBasic()`
   * @private
   * @param {Number} codePoint The basic numeric code point value.
   * @returns {Number} The numeric value of a basic code point (for use in
   * representing integers) in the range `0` to `base - 1`, or `base` if
   * the code point does not represent a value.
   */
  const basicToDigit = function(codePoint) {
  	if (codePoint >= 0x30 && codePoint < 0x3A) {
  		return 26 + (codePoint - 0x30);
  	}
  	if (codePoint >= 0x41 && codePoint < 0x5B) {
  		return codePoint - 0x41;
  	}
  	if (codePoint >= 0x61 && codePoint < 0x7B) {
  		return codePoint - 0x61;
  	}
  	return base;
  };
  
  /**
   * Converts a digit/integer into a basic code point.
   * @see `basicToDigit()`
   * @private
   * @param {Number} digit The numeric value of a basic code point.
   * @returns {Number} The basic code point whose value (when used for
   * representing integers) is `digit`, which needs to be in the range
   * `0` to `base - 1`. If `flag` is non-zero, the uppercase form is
   * used; else, the lowercase form is used. The behavior is undefined
   * if `flag` is non-zero and `digit` has no uppercase form.
   */
  const digitToBasic = function(digit, flag) {
  	//  0..25 map to ASCII a..z or A..Z
  	// 26..35 map to ASCII 0..9
  	return digit + 22 + 75 * (digit < 26) - ((flag != 0) << 5);
  };
  
  /**
   * Bias adaptation function as per section 3.4 of RFC 3492.
   * https://tools.ietf.org/html/rfc3492#section-3.4
   * @private
   */
  const adapt = function(delta, numPoints, firstTime) {
  	let k = 0;
  	delta = firstTime ? floor(delta / damp) : delta >> 1;
  	delta += floor(delta / numPoints);
  	for (/* no initialization */; delta > baseMinusTMin * tMax >> 1; k += base) {
  		delta = floor(delta / baseMinusTMin);
  	}
  	return floor(k + (baseMinusTMin + 1) * delta / (delta + skew));
  };
  
  /**
   * Converts a Punycode string of ASCII-only symbols to a string of Unicode
   * symbols.
   * @memberOf punycode
   * @param {String} input The Punycode string of ASCII-only symbols.
   * @returns {String} The resulting string of Unicode symbols.
   */
  const decode = function(input) {
  	// Don't use UCS-2.
  	const output = [];
  	const inputLength = input.length;
  	let i = 0;
  	let n = initialN;
  	let bias = initialBias;
  
  	// Handle the basic code points: let `basic` be the number of input code
  	// points before the last delimiter, or `0` if there is none, then copy
  	// the first basic code points to the output.
  
  	let basic = input.lastIndexOf(delimiter);
  	if (basic < 0) {
  		basic = 0;
  	}
  
  	for (let j = 0; j < basic; ++j) {
  		// if it's not a basic code point
  		if (input.charCodeAt(j) >= 0x80) {
  			error('not-basic');
  		}
  		output.push(input.charCodeAt(j));
  	}
  
  	// Main decoding loop: start just after the last delimiter if any basic code
  	// points were copied; start at the beginning otherwise.
  
  	for (let index = basic > 0 ? basic + 1 : 0; index < inputLength; /* no final expression */) {
  
  		// `index` is the index of the next character to be consumed.
  		// Decode a generalized variable-length integer into `delta`,
  		// which gets added to `i`. The overflow checking is easier
  		// if we increase `i` as we go, then subtract off its starting
  		// value at the end to obtain `delta`.
  		const oldi = i;
  		for (let w = 1, k = base; /* no condition */; k += base) {
  
  			if (index >= inputLength) {
  				error('invalid-input');
  			}
  
  			const digit = basicToDigit(input.charCodeAt(index++));
  
  			if (digit >= base) {
  				error('invalid-input');
  			}
  			if (digit > floor((maxInt - i) / w)) {
  				error('overflow');
  			}
  
  			i += digit * w;
  			const t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
  
  			if (digit < t) {
  				break;
  			}
  
  			const baseMinusT = base - t;
  			if (w > floor(maxInt / baseMinusT)) {
  				error('overflow');
  			}
  
  			w *= baseMinusT;
  
  		}
  
  		const out = output.length + 1;
  		bias = adapt(i - oldi, out, oldi == 0);
  
  		// `i` was supposed to wrap around from `out` to `0`,
  		// incrementing `n` each time, so we'll fix that now:
  		if (floor(i / out) > maxInt - n) {
  			error('overflow');
  		}
  
  		n += floor(i / out);
  		i %= out;
  
  		// Insert `n` at position `i` of the output.
  		output.splice(i++, 0, n);
  
  	}
  
  	return String.fromCodePoint(...output);
  };
  
  /**
   * Converts a string of Unicode symbols (e.g. a domain name label) to a
   * Punycode string of ASCII-only symbols.
   * @memberOf punycode
   * @param {String} input The string of Unicode symbols.
   * @returns {String} The resulting Punycode string of ASCII-only symbols.
   */
  const encode = function(input) {
  	const output = [];
  
  	// Convert the input in UCS-2 to an array of Unicode code points.
  	input = ucs2decode(input);
  
  	// Cache the length.
  	const inputLength = input.length;
  
  	// Initialize the state.
  	let n = initialN;
  	let delta = 0;
  	let bias = initialBias;
  
  	// Handle the basic code points.
  	for (const currentValue of input) {
  		if (currentValue < 0x80) {
  			output.push(stringFromCharCode(currentValue));
  		}
  	}
  
  	const basicLength = output.length;
  	let handledCPCount = basicLength;
  
  	// `handledCPCount` is the number of code points that have been handled;
  	// `basicLength` is the number of basic code points.
  
  	// Finish the basic string with a delimiter unless it's empty.
  	if (basicLength) {
  		output.push(delimiter);
  	}
  
  	// Main encoding loop:
  	while (handledCPCount < inputLength) {
  
  		// All non-basic code points < n have been handled already. Find the next
  		// larger one:
  		let m = maxInt;
  		for (const currentValue of input) {
  			if (currentValue >= n && currentValue < m) {
  				m = currentValue;
  			}
  		}
  
  		// Increase `delta` enough to advance the decoder's <n,i> state to <m,0>,
  		// but guard against overflow.
  		const handledCPCountPlusOne = handledCPCount + 1;
  		if (m - n > floor((maxInt - delta) / handledCPCountPlusOne)) {
  			error('overflow');
  		}
  
  		delta += (m - n) * handledCPCountPlusOne;
  		n = m;
  
  		for (const currentValue of input) {
  			if (currentValue < n && ++delta > maxInt) {
  				error('overflow');
  			}
  			if (currentValue === n) {
  				// Represent delta as a generalized variable-length integer.
  				let q = delta;
  				for (let k = base; /* no condition */; k += base) {
  					const t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
  					if (q < t) {
  						break;
  					}
  					const qMinusT = q - t;
  					const baseMinusT = base - t;
  					output.push(
  						stringFromCharCode(digitToBasic(t + qMinusT % baseMinusT, 0))
  					);
  					q = floor(qMinusT / baseMinusT);
  				}
  
  				output.push(stringFromCharCode(digitToBasic(q, 0)));
  				bias = adapt(delta, handledCPCountPlusOne, handledCPCount === basicLength);
  				delta = 0;
  				++handledCPCount;
  			}
  		}
  
  		++delta;
  		++n;
  
  	}
  	return output.join('');
  };
  
  /**
   * Converts a Punycode string representing a domain name or an email address
   * to Unicode. Only the Punycoded parts of the input will be converted, i.e.
   * it doesn't matter if you call it on a string that has already been
   * converted to Unicode.
   * @memberOf punycode
   * @param {String} input The Punycoded domain name or email address to
   * convert to Unicode.
   * @returns {String} The Unicode representation of the given Punycode
   * string.
   */
  const toUnicode = function(input) {
  	return mapDomain(input, function(string) {
  		return regexPunycode.test(string)
  			? decode(string.slice(4).toLowerCase())
  			: string;
  	});
  };
  
  /**
   * Converts a Unicode string representing a domain name or an email address to
   * Punycode. Only the non-ASCII parts of the domain name will be converted,
   * i.e. it doesn't matter if you call it with a domain that's already in
   * ASCII.
   * @memberOf punycode
   * @param {String} input The domain name or email address to convert, as a
   * Unicode string.
   * @returns {String} The Punycode representation of the given domain name or
   * email address.
   */
  const toASCII = function(input) {
  	return mapDomain(input, function(string) {
  		return regexNonASCII.test(string)
  			? 'xn--' + encode(string)
  			: string;
  	});
  };
  
  /*--------------------------------------------------------------------------*/
  
  /** Define the public API */
  const punycode = {
  	/**
  	 * A string representing the current Punycode.js version number.
  	 * @memberOf punycode
  	 * @type String
  	 */
  	'version': '2.1.0',
  	/**
  	 * An object of methods to convert from JavaScript's internal character
  	 * representation (UCS-2) to Unicode code points, and back.
  	 * @see <https://mathiasbynens.be/notes/javascript-encoding>
  	 * @memberOf punycode
  	 * @type Object
  	 */
  	'ucs2': {
  		'decode': ucs2decode,
  		'encode': ucs2encode
  	},
  	'decode': decode,
  	'encode': encode,
  	'toASCII': toASCII,
  	'toUnicode': toUnicode
  };
  
  module.exports = punycode;
  