String Regex

regex_constats.dart

class RegexConstants {
  static RegexConstants _instance;
  static RegexConstants get instance {
    if (_instance == null) {
      _instance = RegexConstants._init();
    }
    return _instance;
  }

  RegexConstants._init();
  final String emailRegex =
      r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~]+@[a-zA-Z0-9]+\.[a-zA-Z]+";
  final String passwordRegex = r"^.{4,}$";
  final String userNameRegex = r"^.{4,}$";
}

string_extension.dart

extension StringExtension on String {
bool get isValidEmail {
  return RegExp(RegexConstants.instance.emailRegex).hasMatch(this)
      ? true
      : false;
}
}

tag_regex.dart

main() {
  regExp.allMatches(sampleText).forEach((text) {
    print(text.group(firstValue));
  });
}

final int firstValue = 0;
final String sampleText = """
String: #09asd ext  #qwe-123 #aıaı ext  #şook. ext #aĞ_aİ ext #Ür_ç ext #Şan ext  
#_a34_ ext #sSmiling face with heart-shaped eyesrt ext 
 #gökü ext #aıaı <link>http://google.com/#account</link>
""";
final regExp = RegExp(r"(^|\s)(#[a-z0-9_şıöğçüŞİÖĞÇÜ]+)");

Sample olarak ise: "[email protected]".isValidEmail 👍