putIfAbsent method

V putIfAbsent(K key, V ifAbsent())

As Map.putIfAbsent.

Implementation

V putIfAbsent(K key, V Function() ifAbsent) {
  _checkKey(key);
  return _safeMap.putIfAbsent(key, () {
    var value = ifAbsent();
    _checkValue(value);
    return value;
  });
}