Email Validation in Dart

email_validate.dart

bool validateEmail(String value) {
  Pattern pattern =
      r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
  RegExp regex = new RegExp(pattern);
  return (!regex.hasMatch(value)) ? false : true;
}

void main() {
  print(validateEmail("aslam@gmail.com"));
}

Pattern pattern =
r'^(([^<>()[]\.,;:\s@"]+(.[^<>()[]\.,;:\s@"]+)*)|(".+"))@(([[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}])|(([a-zA-Z-0-9]+.)+[a-zA-Z]{2,}))$';
RegExp regex = new RegExp(pattern);

Why using pattern "The argument type 'Pattern' can't be assigned to the parameter type 'String'."

bool validateEmail(String value) {
Pattern pattern =
r'^(([^<>()[]\.,;:\s@"]+(.[^<>()[]\.,;:\s@"]+)*)|(".+"))@(([[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}])|(([a-zA-Z-0-9]+.)+[a-zA-Z]{2,}))$';
RegExp regex = new RegExp(pattern);
return (!regex.hasMatch(value)) ? false : true;
}

void main() {
print(validateEmail("aslam@gmail.com"));
}