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'use strict';
var ucs2encode = require('./ucs2/encode')
, adapt = require('./lib/adapt')
, floor = Math.floor
/** Highest positive signed 32-bit float value */
, maxInt = 2147483647 // aka. 0x7FFFFFFF or 2^31-1
, initialN = 128, initialBias = 72, delimiter = '-', base = 36, tMin = 1, tMax = 26;
/**
* 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.
*/
var basicToDigit = function (codePoint) {
if (codePoint - 48 < 10) {
return codePoint - 22;
}
if (codePoint - 65 < 26) {
return codePoint - 65;
}
if (codePoint - 97 < 26) {
return codePoint - 97;
}
return base;
};
/** Error messages */
var errors = {
overflow: 'Overflow: input needs wider integers to process',
'not-basic': 'Illegal input >= 0x80 (not a basic code point)',
'invalid-input': 'Invalid input'
};
/**
* A generic error utility function.
* @private
* @param {String} type The error type.
* @returns {Error} Throws a `RangeError` with the applicable error message.
*/
var error = function (type) {
throw new RangeError(errors[type]);
};
/**
* 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.
*/
module.exports = function (input) {
// Don't use UCS-2
var output = [],
inputLength = input.length,
out,
i = 0,
n = initialN,
bias = initialBias,
basic,
j,
index,
oldi,
w,
k,
digit,
t,
/** Cached calculation results */
baseMinusT;
// 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.
basic = input.lastIndexOf(delimiter);
if (basic < 0) {
basic = 0;
}
for (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 (index = basic > 0 ? basic + 1 : 0; index < inputLength; index) {
// `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`.
for (oldi = i, w = 1, k = base; true; k += base) {
if (index >= inputLength) {
error('invalid-input');
}
digit = basicToDigit(input.charCodeAt(index++));
if (digit >= base || digit > floor((maxInt - i) / w)) {
error('overflow');
}
i += digit * w;
t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
if (digit < t) {
break;
}
baseMinusT = base - t;
if (w > floor(maxInt / baseMinusT)) {
error('overflow');
}
w *= baseMinusT;
}
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 ucs2encode(output);
};
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