source: imaps-frontend/node_modules/ajv/lib/compile/ucs2length.js

'use strict';

// https://mathiasbynens.be/notes/javascript-encoding
// https://github.com/bestiejs/punycode.js - punycode.ucs2.decode
module.exports = function ucs2length(str) {
  var length = 0
    , len = str.length
    , pos = 0
    , value;
  while (pos < len) {
    length++;
    value = str.charCodeAt(pos++);
    if (value >= 0xD800 && value <= 0xDBFF && pos < len) {
      // high surrogate, and there is a next character
      value = str.charCodeAt(pos);
      if ((value & 0xFC00) == 0xDC00) pos++; // low surrogate
    }
  }
  return length;
};