Smiley code to unicode converter

main.dart

//Full imoji list -  https://unicode.org/emoji/charts/full-emoji-list.html

String encodeToUtf16(String unicodeString) {
  int rune = unicodeString.runes.first;
  if (rune >= 0x10000) {
    int high = (rune - 0x10000) ~/ 0x400 + 0xD800;
    int low = (rune - 0x10000) % 0x400 + 0xDC00;
    return String.fromCharCode(high) + String.fromCharCode(low);
  } else {
    return unicodeString;
  }
}

String utf16ToEscapedString(List<int> codeUnits) {
  return codeUnits.map((unit) {
    return "\\u${unit.toRadixString(16).padLeft(4, '0').toUpperCase()}";
  }).join();
}

void main() {
  String unicodeString = '\u{2757}';
  String utf16Encoded = encodeToUtf16(unicodeString);
  
  print(utf16Encoded); // 😊
  print(utf16ToEscapedString(utf16Encoded.codeUnits)); // [55357, 56842]
}