extractLocalized method

String? extractLocalized(
  1. String s
)

Extracts substring of preferred language from multilingual string.
Example multilingual string: "Base\ren\bEnglish\rjp\bJapan\rzh_py\bPin-yin".

Use '\r' delimiter among names and '\b' delimiter between each language and name.

Implementation

String? extractLocalized(String s) {
  if (s.trim().isEmpty) {
    return null;
  }

  List<String> langNames = s.toLowerCase().split("\r");
  if (preferredLanguage == null) {
    return langNames[0];
  }
  String lang = preferredLanguage!;

  String? fallback;
  for (int i = 1; i < langNames.length; i++) {
    List<String> langName = langNames[i].split("\b");
    if (langName.length != 2) {
      continue;
    }

    // Perfect match
    if (langName[0] == preferredLanguage) {
      return langName[1];
    }

    // Fall back to base, e.g. zh-min-lan -> zh
    if (fallback == null &&
        !langName[0].contains("-") &&
        (lang.contains("-") || lang.contains("_")) &&
        lang.startsWith(langName[0])) {
      fallback = langName[1];
    }
  }
  return (fallback != null) ? fallback : langNames[0];
}